naca full-scale wind: Topics by Science.gov

Sample records for naca full-scale wind

Full-Scale Tests of NACA Cowlings

NASA Technical Reports Server (NTRS)

Theodorsen, Theodore; Brevoort, M J; Stickle, George W

1937-01-01

A comprehensive investigation has been carried on with full-scale models in the NACA 20-foot wind tunnel, the general purpose of which is to furnish information in regard to the physical functioning of the composite propeller-nacelle unit under all conditions of take-off, taxiing, and normal flight. This report deals exclusively with the cowling characteristics under condition of normal flight and includes the results of tests of numerous combinations of more than a dozen nose cowlings, about a dozen skirts, two propellers, two sizes of nacelle, as well as various types of spinners and other devices.
Determination of Boundary-Layer Transition on Three Symmetrical Airfoils in the NACA Full-Scale Wind Tunnel

NASA Technical Reports Server (NTRS)

Silverstein, Abe; Becker, John V

1938-01-01

For the purpose of studying the transition from laminar to turbulent flow, boundary-layer measurements were made in the NACA full-scale wind tunnel on three symmetrical airfoils of NACA 0009, 0012, and 0018 sections. The effects of variations in lift coefficient, Reynolds number, and airfoil thickness on transition were investigated. Air speed in the boundary layer was measured by total-head tubes and by hot wires; a comparison of transition as indicated by the two techniques was obtained. The results indicate no unique value of Reynolds number for the transition, whether the Reynolds number is based upon the distance along the chord or upon the thickness of the boundary layer at the transition point. In general, the transition is not abrupt and occurs in a region that varies in length as a function of the test conditions.
Development of Cowling for Long-nose Air-cooled Engine in the NACA Full-scale Wind Tunnel

NASA Technical Reports Server (NTRS)

Guryansky, Eugene R.; Silverstein, Abe

1941-01-01

An investigation of cowlings for long-nose radial engines was made on the Curtiss XP-42 fighter in the NACA full-scale wind tunnel. The unsatisfactory aerodynamic characteristics of all the cowlings with scoop inlets tested led to the development of the annular high-velocity inlet cowlings. Tests showed that ratio of cooling-air velocity at cowling inlet to stream velocity should not be less than 0.5 for this type of cowling and that critical compressibility speed can be extended to more than 500 mph at 20,000 ft altitude.
Ice Accretions and Full-Scale Iced Aerodynamic Performance Data for a Two-Dimensional NACA 23012 Airfoil

NASA Technical Reports Server (NTRS)

Addy, Harold E., Jr.; Broeren, Andy P.; Potapczuk, Mark G.; Lee, Sam; Guffond, Didier; Montreuil, Emmanuel; Moens, Frederic

2016-01-01

This report documents the data collected during the large wind tunnel campaigns conducted as part of the SUNSET project (StUdies oN Scaling EffecTs due to ice) also known as the Ice-Accretion Aerodynamics Simulation study: a joint effort by NASA, the Office National d'Etudes et Recherches Aérospatiales (ONERA), and the University of Illinois. These data form a benchmark database of full-scale ice accretions and corresponding ice-contaminated aerodynamic performance data for a two-dimensional (2D) NACA 23012 airfoil. The wider research effort also included an analysis of ice-contaminated aerodynamics that categorized ice accretions by aerodynamic effects and an investigation of subscale, low- Reynolds-number ice-contaminated aerodynamics for the NACA 23012 airfoil. The low-Reynolds-number investigation included an analysis of the geometric fidelity needed to reliably assess aerodynamic effects of airfoil icing using artificial ice shapes. Included herein are records of the ice accreted during campaigns in NASA Glenn Research Center's Icing Research Tunnel (IRT). Two different 2D NACA 23012 airfoil models were used during these campaigns; an 18-in. (45.7-cm) chord (subscale) model and a 72-in. (182.9-cm) chord (full-scale) model. The aircraft icing conditions used during these campaigns were selected from the Federal Aviation Administration's (FAA's) Code of Federal Regulations (CFR) Part 25 Appendix C icing envelopes. The records include the test conditions, photographs of the ice accreted, tracings of the ice, and ice depth measurements. Model coordinates and pressure tap locations are also presented. Also included herein are the data recorded during a wind tunnel campaign conducted in the F1 Subsonic Pressurized Wind Tunnel of ONERA. The F1 tunnel is a pressured, high- Reynolds-number facility that could accommodate the full-scale (72-in. (182.9-cm) chord) 2D NACA 23012 model. Molds were made of the ice accreted during selected test runs of the full-scale model
Analysis of wind-tunnel stability and control tests in terms of flying qualities of full-scale airplanes

NASA Technical Reports Server (NTRS)

Kayten, Gerald G

1945-01-01

The analysis of results of wind-tunnel stability and control tests of powered airplane models in terms of the flying qualities of full-scale airplanes is advocated. In order to indicated the topics upon which comments are considered desirable in the report of a wind-tunnel stability and control investigation and to demonstrate the nature of the suggested analysis, the present NACA flying-qualities requirements are discussed in relation to wind-tunnel tests. General procedures for the estimation of flying qualities from wind-tunnel tests are outlined.
NACA Engineer Examines Wind Tunnel Compressor Blades

NASA Image and Video Library

1955-09-21

An engineer examines the main compressor for the 10- by 10-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The engineers were preparing the new wind tunnel for its initial runs in early 1956. The 10- by 10 was the most powerful propulsion wind tunnel in the nation. The facility was part of Congress’ Unitary Plan Act which coordinated wind tunnel construction at the NACA, Air Force, industry, and universities. The 10- by 10 was the largest of the three NACA tunnels built under the act. The 20-foot diameter eight-stage axial flow compressor, seen in this photograph, could generate air flows up to Mach 2.5 through the test section. The stainless steel compressor had 584 blades ranging from 1.8 to 3.25 feet in length. This main compressor was complemented by a secondary axial flow compressor. Working in tandem the two could generate wind streams up to Mach 3.5. The Cleveland Chamber of Commerce presented NACA Lewis photographer Bill Bowles with a second place award for this photograph in their Business and Professional category. The photograph was published in October 1955 edition of its periodical, The Clevelander, which highlighted local professional photographers. Fellow Lewis photographer Gene Giczy won second place in another category for a photograph of Cleveland Municipal Airport.
Preliminary Tests in the NACA Free-Spinning Wind Tunnel

NASA Technical Reports Server (NTRS)

Zimmerman, C H

1937-01-01

Typical models and the testing technique used in the NACA free-spinning wind tunnel are described in detail. The results of tests on two models afford a comparison between the spinning characteristics of scale models in the tunnel and of the airplanes that they represent.
Preliminary Full-Scale Wind-Tunnel Investigation of Wing Ducts for Radiators, Special Report

NASA Technical Reports Server (NTRS)

Silverstein, Abe; Nickle, F. R.

1938-01-01

Wing ducts for liquid-cooled engine radiators have been investigated in the N.A.C.A. full-scale wind tunnel on a large model airplane. Th e tests were made to determine the relative merits of several types of duct and radiator installations for an airplane of a particular des ign. In the test program the principal duct dimensions were system atically varied, and the results are therefore somewhat applicable to the general problems of wing duct design, although they should be co nsidered as preliminary and only indicative of the inherent possibil ities.
Ramjet Testing in the NACA's Altitude Wind Tunnel

NASA Image and Video Library

1946-02-21

A 20-inch diameter ramjet installed in the Altitude Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The Altitude Wind Tunnel was used in the 1940s to study early ramjet configurations. Ramjets provide a very simple source of propulsion. They are basically a tube which takes in high-velocity air, ignites it, and then expels the expanded airflow at a significantly higher velocity for thrust. Ramjets are extremely efficient and powerful but can only operate at high speeds. Therefore a turbojet or rocket was needed to launch the vehicle. This NACA-designed 20-inch diameter ramjet was installed in the Altitude Wind Tunnel in May 1945. The ramjet was mounted under a section of wing in the 20-foot diameter test section with conditioned airflow ducted directly to the engine. The mechanic in this photograph was installing instrumentation devices that led to the control room. NACA researchers investigated the ramjet’s overall performance at simulated altitudes up to 47,000 feet. Thrust measurements from these runs were studied in conjunction with drag data obtained during small-scale studies in the laboratory’s small supersonic tunnels. An afterburner was attached to the ramjet during the portions of the test program. The researchers found that an increase in altitude caused a reduction in the engine’s horsepower. They also determined the optimal configurations for the flameholders, which provided the engine’s ignition source.
Comparative Flight and Full-Scale Wind-Tunnel Measurements of the Maximum Lift of an Airplane

NASA Technical Reports Server (NTRS)

Silverstein, Abe; Katzoff, S; Hootman, James A

1938-01-01

Determinations of the power-off maximum lift of a Fairchild 22 airplane were made in the NACA full-scale wind tunnel and in flight. The results from the two types of test were in satisfactory agreement. It was found that, when the airplane was rotated positively in pitch through the angle of stall at rates of the order of 0.1 degree per second, the maximum lift coefficient was considerably higher than that obtained in the standard tests, in which the forces are measured with the angles of attack fixed. Scale effect on the maximum lift coefficient was also investigated.
Full-Scale Wind-Tunnel Tests of a PCA-2 Autogiro Rotor

NASA Technical Reports Server (NTRS)

Wheatley, John B; Hood, Manley J

1935-01-01

This report presents the results of force tests on and air-flow surveys near PCA-2 autogiro rotor in the NACA full-scale wind tunnel. The force tests were made at three pitch settings and several rotor speeds; the effect of fairing protuberances on the rotor blade was determined. Induced downwash and yaw angles were determined at low tip-speed ratios in a plane 1 1/2 feet above the path of the blade tips. The results show that the maximum l/d of the rotor cannot be appreciably increased by increasing the blade pitch angle above about 4.5 degrees at the blade tip; that the protuberances on the blades cause more than 5 percent of the total rotor drag; and that the rotor center-of-pressure travel is very small.
Full-scale Wind-tunnel Research on Tail Buffeting and Wing-fuselage Interference of a Low-wing Monoplane

NASA Technical Reports Server (NTRS)

Hood, Manley J; White, James A

1933-01-01

Some preliminary results of full scale wind tunnel testing to determine the best means of reducing the tail buffeting and wing-fuselage interference of a low-wing monoplane are given. Data indicating the effects of an engine cowling, fillets, auxiliary airfoils of short span, reflexes trailing edge, propeller slipstream, and various combinations of these features are included. The best all-round results were obtained by the use of fillets together with the National Advisory Committee for Aeronautics (NACA) cowling. This combination reduced the tail buffeting oscillations to one-fourth of their original amplitudes, increased the maximum lift 11 percent, decreased the minimum drag 9 percent, and increased the maximum ratio of lift to drag 19 percent.
Computer investigations of the turbulent flow around a NACA2415 airfoil wind turbine

NASA Astrophysics Data System (ADS)

Driss, Zied; Chelbi, Tarek; Abid, Mohamed Salah

2015-12-01

In this work, computer investigations are carried out to study the flow field developing around a NACA2415 airfoil wind turbine. The Navier-Stokes equations in conjunction with the standard k-ɛ turbulence model are considered. These equations are solved numerically to determine the local characteristics of the flow. The models tested are implemented in the software "SolidWorks Flow Simulation" which uses a finite volume scheme. The numerical results are compared with experiments conducted on an open wind tunnel to validate the numerical results. This will help improving the aerodynamic efficiency in the design of packaged installations of the NACA2415 airfoil type wind turbine.
Full-scale monitoring of wind and suspension bridge response

NASA Astrophysics Data System (ADS)

Snæbjörnsson, J. T.; Jakobsen, J. B.; Cheynet, E.; Wang, J.

2017-12-01

Monitoring of real structures is important for many reasons. For structures susceptible to environmental actions, full-scale observations can provide valuable information about the environmental conditions at the site, as well as the characteristics of the excitation acting on the structure. The recorded data, if properly analyzed, can be used to validate and/or update experiments and models used in the design of new structures, such as the load description and modelling of the structural response. Various aspects of full-scale monitoring are discussed in the paper and the full-scale wind engineering laboratory at the Lysefjord suspension bridge introduced. The natural excitation of the bridge comes from wind and traffic. The surrounding terrain is complex and its effect on the wind flow can only be fully studied on site, in full-scale. The monitoring program and associated data analysis are described. These include various studies of the relevant turbulence characteristics, identification of dynamic properties and estimation of wind- and traffic-induced response parameters. The overall monitoring activity also included a novel application of the remote optical sensing in bridge engineering, which is found to have an important potential to complement traditional “single-point” wind observations by sonic anemometers.
Comparison of NACA 6-series and 4-digit airfoils for Darrieus wind turbines

NASA Astrophysics Data System (ADS)

Migliore, P. G.

1983-08-01

The aerodynamic efficiency of Darrieus wind turbines as effected by blade airfoil geometry was investigated. Analysis was limited to curved-bladed machines having rotor solidities of 7-21 percent and operating at a Reynolds number of 3 x 10 to the 6th. Ten different airfoils, having thickness-to-chord ratios of 12, 15, and 18 percent, were studied. Performance estimates were made using a blade element/momentum theory approach. Results indicated that NACA 6-series airfoils yield peak power coefficients as great as NACA 4-digit airfoils and have broader and flatter power coefficient-tip speed ratio curves. Sample calculations for an NACA 63(2)-015 airfoil showed an annual energy output increase of 17-27 percent, depending on rotor solidity, compared to an NACA 0015 airfoil.
NACA Technician Cleans a Ramjet in 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1950-04-21

A technician at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory cleans the pitot tube on a 16-inch diameter ramjet in the 8- by 6-Foot Supersonic Wind Tunnel. Pitot tubes are a measurement device used to determine the flow velocity at a specific location in the air stream, not the average velocity of the entire wind stream. NACA Lewis was in the midst of a multi-year program to determine the feasibility of ramjets and design improvements that could be employed for all models. The advantage of the ramjet was its ability to process large volumes of combustion air, resulting in the burning of fuel at the optimal stoichiometric temperatures. This was not possible with turbojets. The higher the Mach number, the more efficient the ramjet operated. The 8- by 6 Supersonic Wind Tunnel had been in operation for just over one year when this photograph was taken. The facility was the NACA’s largest supersonic tunnel and the only facility capable of running an engine at supersonic speeds. The 8- by 6 tunnel was also equipped with a Schlieren camera system that captured the air flow gradient as it passes over the test setup. The ramjet tests in the 8- by 6 tunnel complemented the NACA Lewis investigations using aircraft, the Altitude Wind Tunnel and smaller supersonic tunnels. Researchers studied the ramjet’s performance at different speeds and varying angles -of -attack.
Boundary-Layer Transition on the N.A.C.A. 0012 and 23012 Airfoils in the 8-Foot High-Speed Wind Tunnel, Special Report

NASA Technical Reports Server (NTRS)

Becker, John V.

1940-01-01

Determinations of boundary-layer transition on the NACA 0012 and 2301 airfoils were made in the 8-foot high-speed wind tunnel over a range of Reynolds Numbers from 1,600,000 to 16,800,000. The results are of particular significance as compared with flight tests and tests in wind tunnels of appreciable turbulence because of the extremely low turbulence in the high-speed tunnel. A comparison of the results obtained on NACA 0012 airfoils of 2-foot and 5-foot chord at the same Reynolds Number permitted an evaluation of the effect of compressibility on transition. The local skin friction along the surface of the NACA 0012 airfoil was measured at a Reynolds Number of 10,000,000. For all the lift coefficient at which tests were made, transition occurred in the region of estimated laminar separation at the low Reynolds Numbers and approach the point of minimum static pressure as a forward limit at the high Reynolds Numbers. The effect of compressibility on transition was slight. None of the usual parameters describing the local conditions in the boundary layer near the transition point served as an index for locating the transition point. As a consequence of the lower turbulence in the 8-foot high-speed tunnel, the transition points occurred consistently farther back along the chord than those measured in the NACA full-scale tunnel. An empirical relation for estimating the location of the transition point for conventional airfoils on the basis of static-pressure distribution and Reynolds Number is presented.
Rocket Research Presentation at the NACA's 1947 Inspection

NASA Image and Video Library

1947-10-21

Researcher John Sloop briefs visitors on his latest rocket engine research during the 1947 Inspection at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The NACA had been hosting annual Aircraft Engineering Conferences, better known as Inspections, since 1926. Individuals from the manufacturing industry, military, and university settings were invited to tour the NACA laboratories. There were a series of stops on the tour, mostly at test facilities, where researchers would brief the group on the latest efforts in their particular field. The Inspections grew in size and scope over the years and by the mid-1940s required multiple days. The three-day 1947 Inspection was the first time the event was held at NACA Lewis. Over 800 scientists, industrialists, and military leaders attended the three-day event. Talks were given at the Altitude Wind Tunnel, Four Burner Area, Engine Research Building, and other facilities. An array of topics were discussed, including full-scale engine testing, ramjets, axial-flow compressors, turbojets, fuels, icing, and materials. The NACA Lewis staff and their families were able to view the same presentations after the Inspection was over. Sloop, a researcher in the Fuels and Thermodynamics Division, briefed visitors on NACA Lewis’ early research in rocket engine propellants, combustion, and cooling. This early NACA Lewis work led to the development of liquid hydrogen as a viable propellant in the late 1950s.
Space capsule mounted in the Full Scale Wind Tunnel

NASA Image and Video Library

1959-01-22

The Mercury space capsule undergoing tests in Full Scale Wind Tunnel, January 1959. Photograph published in Winds of Change, 75th Anniversary NASA publication, page 75, by James Schultz. Also Photograph published in Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958, page 389, by James R. Hansen.
Horizontal Axis Wind Turbine Experiments at Full-Scale Reynolds Numbers

NASA Astrophysics Data System (ADS)

Miller, Mark; Kiefer, Janik; Nealon, Tara; Westergaard, Carsten; Hultmark, Marcus

2017-11-01

Achieving high Reynolds numbers on a wind turbine model remains a major challenge for experimentalists. Since Reynolds number effects need to be captured accurately, matching this parameter is of great importance. The challenge stems from the large scale ratio between model and full-size, typically on the order of 1:100. Traditional wind tunnels are limited due to finite tunnel size, with velocity as the only free-parameter available for increasing the Reynolds number. Unfortunately, increasing the velocity 100 times is untenable because it violates Mach number matching with the full-scale and results in unfeasible rotation rates. Present work in Princeton University's high pressure wind tunnel makes it possible to evaluate the Reynolds number sensitivity with regard to wind turbine aerodynamics. This facility, which uses compressed air as the working fluid, allows for adjustment of the Reynolds number, via the fluid density, independent of the Tip Speed Ratio (TSR) and Mach number. Power and thrust coefficients will be shown as a function of Reynolds number and TSR for a model wind turbine. The Reynolds number range investigated exceeds 10 ×106 based on diameter and free-stream conditions or 3 ×106 based on the tip chord, matching those of the full-scale. National Science Foundation and Andlinger Center for Energy and the Environment.

Model Wind Turbines Tested at Full-Scale Similarity

NASA Astrophysics Data System (ADS)

Miller, M. A.; Kiefer, J.; Westergaard, C.; Hultmark, M.

2016-09-01

The enormous length scales associated with modern wind turbines complicate any efforts to predict their mechanical loads and performance. Both experiments and numerical simulations are constrained by the large Reynolds numbers governing the full- scale aerodynamics. The limited fundamental understanding of Reynolds number effects in combination with the lack of empirical data affects our ability to predict, model, and design improved turbines and wind farms. A new experimental approach is presented, which utilizes a highly pressurized wind tunnel (up to 220 bar). It allows exact matching of the Reynolds numbers (no matter how it is defined), tip speed ratios, and Mach numbers on a geometrically similar, small-scale model. The design of a measurement and instrumentation stack to control the turbine and measure the loads in the pressurized environment is discussed. Results are then presented in the form of power coefficients as a function of Reynolds number and Tip Speed Ratio. Due to gearbox power loss, a preliminary study has also been completed to find the gearbox efficiency and the resulting correction has been applied to the data set.
Full-Scale Tests of a New Type NACA Nose-Slot Cowling

NASA Technical Reports Server (NTRS)

Theodorsen, Theodore; Brevoort, M J; Stickle, George W; Gough, M N

1937-01-01

An extended experimental study has been made in regard to the various refinements in the design of engine cowlings as related to the propeller-nacelle unit as a whole, under conditions corresponding to take-off, climb, and normal flight. The tests were all conducted at full scale in the 20-foot wind tunnel. This report presents the results of a novel type of engine cowling, characterized by the fact that the exit opening discharging the cooling air is not, as usual, located behind the engine but at the foremost extremity or nose of the cowling. The efficiency is found to be high, owing to the fact that higher velocities may be used in the exit opening.
Wind-tunnel investigation of an NACA 23012 airfoil with 30 percent-chord venetian-blind flaps

NASA Technical Reports Server (NTRS)

Rogallo, F M; Spano, Bartholomew S

1942-01-01

Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a NACA 23012 airfoil with 30-percent-chord venetian-blind flaps having one, two, three, and four slats of Clark y section. The three-slat arrangements was aerodynamically the best of those tested but showed practically no improvement over the comparable arrangement used in the preliminary tests published in NACA Technical Report No. 689. The multiple-slat flaps gave slightly higher lift coefficients than the one-slat (Fowler) flap but gave considerably greater pitching-moment coefficients. An analysis of test data indicates that substitution of a thicker and more cambered section for the Clark y slats should improve the aerodynamic and the structural characteristics of the venetian-blind flap.
Lateral stability and control tests of the XP-77 airplane in the NACA full-scale tunnel, 16 June 1944

NASA Technical Reports Server (NTRS)

Czarnecki, K. R.; Donlan, C. J.

1976-01-01

Tests were made in the NACA full-scale tunnel to determine the lateral stability and control characteristics of the XP-77 airplane. Measurements were made of the forces and moments on the airplane at various angles of attack and angles of yaw. The measurements were made with the propeller removed and with the propeller installed and operating at various thrust coefficients, and with the landing flaps retracted and deflected. The effects of aileron, elevator, and rudder deflection on control surface effectiveness and hinge moments were determined. The tests were planned to obtain the data required to evaluate as completely as possible the Army Air Force requirements on lateral stability and control for pursuit-type airplanes.
Investigation of spoiler ailerons for use as speed brakes or glide-path controls on two NACA 65-series wings equipped with full-span slotted flaps

NASA Technical Reports Server (NTRS)

Fischel, Jack; Watson, James M

1951-01-01

A wind-tunnel investigation was made to determine the characteristics of spoiler ailerons used as speed brakes or glide-path controls on an NACA 65-210 wing and an NACA 65-215 wing equipped with full-span slotted flaps. Several plug aileron and retractable-aileron configurations were investigated on two wing models with the full-span flaps retracted and deflected. Tests were made at various Mach numbers between 0.13 and 0.71. The results of this investigation have indicated that the use of plug or retractable ailerons, either alone or in conjunction with wing flaps, as speed brakes or glide-path controls is feasible and very effective.
Scale Effect on Clark Y Airfoil Characteristics from NACA Full-Scale Wind-Tunnel Tests

NASA Technical Reports Server (NTRS)

Silverstein, Abe

1935-01-01

This report presents the results of wind tunnel tests conducted to determine the aerodynamic characteristics of the Clark Y airfoil over a large range of Reynolds numbers. Three airfoils of aspect ratio 6 and with 4, 6, and 8 foot chords were tested at velocities between 25 and 118 miles per hour, and the characteristics were obtained for Reynolds numbers (based on the airfoil chord) in the range between 1,000,000 and 9,000,000 at the low angles of attack, and between 1,000,000 and 6,000,000 at maximum lift. With increasing Reynolds number the airfoil characteristics are affected in the following manner: the drag at zero lift decreases, the maximum lift increases, the slope of the lift curve increases, the angle of zero lift occurs at smaller negative angles, and the pitching moment at zero lift does not change appreciably.
Preliminary wind-tunnel investigation of an NACA 23012 airfoil with various arrangements of venetian-blind flaps

NASA Technical Reports Server (NTRS)

Wenzinger, Carl J; Harris, Thomas A

1940-01-01

Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a large-chord NACA 23012 airfoil with several arrangements of venetian-blind flaps to determine the aerodynamic section characteristics as affected by the over-all flap chord, the chords of the slats used to form the flap, the slat spacing, the number of slats and the position of the flap with respect to the wing. Complete section data are given in the form of graphs for all the combinations tested.
A Full-Scale Fatigue Test of 9-m CX-100 Wind Turbine Blades

DTIC Science & Technology

2011-09-01

A Full-Scale Fatigue Test of 9-m CX-100 Wind Turbine Blades G. PARK, K. M. FARINHOLT, S. G. TAYLOR and C. R. FARRAR ABSTRACT This paper...presents the SHM result of a 9m CX-100 wind turbine blade under full- scale fatigue loads. The test was performed at the National Renewable Energy...surface of the blade. The blade underwent fatigue excitation at 1.8 Hz for defined intervals, and data from the sensors were collected between and
The requirements for a new full scale subsonic wind tunnel

NASA Technical Reports Server (NTRS)

Kelly, M. W.; Mckinney, M. O.; Luidens, R. W.

1972-01-01

Justification and requirements are presented for a large subsonic wind tunnel capable of testing full scale aircraft, rotor systems, and advanced V/STOL propulsion systems. The design considerations and constraints for such a facility are reviewed, and the trades between facility test capability and costs are discussed.
Desktop Access to Full-Text NACA and NASA Reports: Systems Developed by NASA Langley Technical Library

NASA Technical Reports Server (NTRS)

Ambur, Manjula Y.; Adams, David L.; Trinidad, P. Paul

1997-01-01

NASA Langley Technical Library has been involved in developing systems for full-text information delivery of NACA/NASA technical reports since 1991. This paper will describe the two prototypes it has developed and the present production system configuration. The prototype systems are a NACA CD-ROM of thirty-three classic paper NACA reports and a network-based Full-text Electronic Reports Documents System (FEDS) constructed from both paper and electronic formats of NACA and NASA reports. The production system is the DigiDoc System (DIGItal Documents) presently being developed based on the experiences gained from the two prototypes. DigiDoc configuration integrates the on-line catalog database World Wide Web interface and PDF technology to provide a powerful and flexible search and retrieval system. It describes in detail significant achievements and lessons learned in terms of data conversion, storage technologies, full-text searching and retrieval, and image databases. The conclusions from the experiences of digitization and full- text access and future plans for DigiDoc system implementation are discussed.
Evaluation of Icing Scaling on Swept NACA 0012 Airfoil Models

NASA Technical Reports Server (NTRS)

Tsao, Jen-Ching; Lee, Sam

2012-01-01

Icing scaling tests in the NASA Glenn Icing Research Tunnel (IRT) were performed on swept wing models using existing recommended scaling methods that were originally developed for straight wing. Some needed modifications on the stagnation-point local collection efficiency (i.e., beta(sub 0) calculation and the corresponding convective heat transfer coefficient for swept NACA 0012 airfoil models have been studied and reported in 2009, and the correlations will be used in the current study. The reference tests used a 91.4-cm chord, 152.4-cm span, adjustable sweep airfoil model of NACA 0012 profile at velocities of 100 and 150 knot and MVD of 44 and 93 mm. Scale-to-reference model size ratio was 1:2.4. All tests were conducted at 0deg angle of attack (AoA) and 45deg sweep angle. Ice shape comparison results were presented for stagnation-point freezing fractions in the range of 0.4 to 1.0. Preliminary results showed that good scaling was achieved for the conditions test by using the modified scaling methods developed for swept wing icing.
Pressure distribution over an NACA 23012 airfoil with an NACA 23012 external-airfoil flap

NASA Technical Reports Server (NTRS)

Wenzinger, Carl J

1938-01-01

Report presents the results of pressure-distribution tests of an NACA 23012 airfoil with an NACA 23012 external airfoil flap made in the 7 by 10-foot wind tunnel. The pressures were measured on the upper and lower surfaces at one chord section on both the main airfoil and on the flap for several different flap deflections and at several angles of attack. A test installation was used in which the airfoil was mounted horizontally in the wind tunnel between vertical end planes so that two-dimensional flow was approximated. The data are presented in the form of pressure-distribution diagrams and as graphs of calculated coefficients for the airfoil-and-flap combination and for the flap alone.
Turbulence effects on a full-scale 2.5 MW horizontal axis wind turbine

NASA Astrophysics Data System (ADS)

Chamorro, Leonardo; Lee, Seung-Jae; Olsen, David; Milliren, Chris; Marr, Jeff; Arndt, Roger; Sotiropoulos, Fotis

2012-11-01

Power fluctuations and fatigue loads are among the most significant problems that wind turbines face throughout their lifetime. Turbulence is the common driving mechanism that triggers instabilities on these quantities. We investigate the complex response of a full-scale 2.5 MW wind turbine under nearly neutral thermal stratification. The study is performed in the EOLOS Wind Energy Research Field Station of the University of Minnesota. An instrumented 130 meter meteorological tower located upstream of a Clipper Liberty C96 wind turbine is used to characterize the turbulent flow and atmospheric conditions right upstream of the wind turbine. High resolution and synchronous measurements of the wind velocity, turbine power and strain at the tower foundation are used to determine the scale-to-scale interaction between flow and the wind turbine. The structure of the fluctuating turbine power and instantaneous stresses are studied in detail. Important insights about the role of turbulent and coherent motions as well as strong intermittent gusts will be discussed. Funding was provided by Department of Energy DOE (DE-EE0002980) and Xcel Energy through the Renewable Development Fund (grant RD3-42).
The Aerodynamic Characteristics of Six Full-Scale Propellers Having Different Airfoil Sections

NASA Technical Reports Server (NTRS)

Biermann, David; Hartman, Edwin P

1939-01-01

Wind-tunnel tests are reported of six 3-blade 10-foot propellers operated in front of a liquid-cooled engine nacelle. The propellers were identical except for blade airfoil sections, which were: Clark y, R.A.F. 6, NACA 4400, NACA 2400-34, NACA 2rsub200, and NACA 6400. The range of blade angles investigated extended for 15 degrees to 40 degrees for all propellers except the Clark y, for which it extended to 45 degrees. The results showed that the range in maximum efficiency between the highest and lowest values was about 3 percent. The highest efficiencies were for the low-camber sections.
Investigation of Full-Scale Split Trailing-Edge Wing Flaps with Various Chords and Hinge Locations

NASA Technical Reports Server (NTRS)

Wallace, Rudolf

1936-01-01

This report gives the results of an investigation conducted in the NACA full-scale wind tunnel on a small parasol monoplane equipped with three different split trailing-edge wing flaps. The object of the investigation was to determine and correlate data on the characteristics of the airplane and flaps as affected by variation in flap chord, flap deflection, and flap location along the wing chord. The results give the lift, the drag, and the pitching moment characteristics of the airplane, and the flap forces and moments, the pressure distribution over the flaps and wing at one section, and the downwash characteristics of the flap and wing combinations.
A critical assessment of wind tunnel results for the NACA 0012 airfoil

NASA Technical Reports Server (NTRS)

Mccroskey, W. J.

1987-01-01

A large body of experimental results, obtained in more than 40 wind tunnels on a single, well-known two-dimensional configuration, has been critically examined and correlated. An assessment of some of the possible sources of error has been made for each facility, and data which are suspect have been identified. It was found that no single experiment provided a complete set of reliable data, although one investigation stands out as superior in many respects. However, from the aggregate of data the representative properties of the NACA 0012 airfoil can be identified with reasonable confidence over wide ranges of Mach number, Reynolds number, and angles of attack. This synthesized information can now be used to assess and validate existing and future wind tunnel results and to evaluate advanced Computational Fluid Dynamics codes.
Characterization of wind velocities in the wake of a full scale wind turbine using three ground-based synchronized WindScanners

NASA Astrophysics Data System (ADS)

Yazicioglu, Hasan; Angelou, Nikolas; Mikkelsen, Torben; José Trujillo, Juan

2016-09-01

The wind energy community is in need of detailed full-field measurements in the wake of wind turbines. Here, three dimensional(3D) wind vector field measurements obtained in the near-wake region behind a full-scale test turbine are presented. Specifically, the wake of a NEG Nordtank turbine, installed at Risoe test field, has been measured from 0 to 2 diameters downstream. For this, three ground-based synchronised short-range WindScanners and a spinner lidar have been used. The 3D wind velocity field has been reconstructed in horizontal and vertical planes crossing the hub. The 10-min mean values of the three wind components reveal detailed information regarding the wake properties while propagating downwind over flat terrain. Furthermore, the wake centre is tracked from the measurements and its meander is investigated as function of yaw misalignment of the turbine. The centre-line wake deficit is calculated both in a Nacelle and Moving Frame of Reference. The results can be used in quantitative validation of numerical wake models.
Investigation of correlation between full-scale and fifth-scale wind tunnel tests of a Bell helicopter Textron Model 222

NASA Technical Reports Server (NTRS)

Squires, P. K.

1982-01-01

Reasons for lack of correlation between data from a fifth-scale wind tunnel test of the Bell Helicopter Textron Model 222 and a full-scale test of the model 222 prototype in the NASA Ames 40-by 80-foot tunnel were investigated. This investigation centered around a carefully designed fifth-scale wind tunnel test of an accurately contoured model of the Model 222 prototype mounted on a replica of the full-scale mounting system. The improvement in correlation for drag characteristics in pitch and yaw with the fifth-scale model mounted on the replica system is shown. Interference between the model and mounting system was identified as a significant effect and was concluded to be a primary cause of the lack of correlation in the earlier tests.
Wind-tunnel Tests of the NACA 45-125 Airfoil: A Thick Airfoil for High-Speed Airplanes

NASA Technical Reports Server (NTRS)

Delano, James B.

1940-01-01

Investigations of the pressure distribution, the profile drag, and the location of transition for a 30-inch-chord 25-percent-thick N.A,C.A. 45-125 airfoil were made in the N.A.C.A 8-foot high-speed wind tunnel for the purpose of aiding in the development of a thick wing for high-speed airplanes. The tests were made at a lift coefficient of 0.1 for Reynolds Numbers from 1,750,000 to 8,690,000, corresponding to speeds from 80 to 440 miles per hour at 59 F. The effect on the profile drag of fixing the transition point was also investigated. The effect of compressibility on the rate of increase of pressure coefficients was found to be greater than that predicted by a simplified theoretical expression for thin wings. The results indicated that, for a lift coefficient of 0.1, the critical speed of the N.A.C,A. 45-125 airfoil was about 460 miles per hour at 59 F,. The value of the profile-drag coefficient at a Reynolds Number of 4,500,000 was 0.0058, or about half as large as the value for the N.A,C,A. 0025 airfoil. The increase in the profile-drag coefficient for a given movement of the transition point was about three times as large as the corresponding increase for the N.A.C,A. 0012 airfoil. Transition determinations indicated that, for Reynolds Numbers up to ?,000,000, laminar boundary 1ayers were maintained over approximately 40 percent of the upper and the lower surfaces of the airfoil.
Full-Scale Tests of Several Propellers Equipped with Spinners, Cuffs, Airfoil and Round Shanks, and NACA 16-Series Sections, Special Report

NASA Technical Reports Server (NTRS)

Biermann, David; Hartman, Edwin P.; Pepper, Edward

1940-01-01

Wind-tunnel tests of several propeller, cuff, and spinner combinations were conducted in the 20 foot propeller-research tunnel. Three propellers, which ranged in diameter from 8.4 to 11.25 feet, were tested at the front end of a streamline body incorporating spinners of two diameters. The tests covered a blade angle range from 20 deg to 65 deg. The effect of spinner diameter and propeller cuffs on the characteristics of one propeller was determined. Test were also conducted using a propeller which incorporated aerodynamically good shank sections and using one which incorporated the NACA 16 series sections for the outer 20 percent of the blades. Compressibility effects were not measured, owing to the low testing speeds. The results indicated that a conventional propeller was slightly more efficient when tested in conjunction with a 28 inch diameter spinner than with a 23 inch spinner, and that cuffs increased the efficiency as well as the power absorption characteristics. A propeller having good aerodynamic shanks was found to be definitely superior from the efficiency standpoint to a conventional round-shank propeller with or without cuffs; this propeller would probably be considered structurally impracticable, however. The propeller incorporating the NACA 16 series sections at the tims were found to have a slightly higher efficiency than a conventional propeller; the take-off characteristics appeared to be equally good. The effects noted above probably would be accentuated at helical speeds at which compressibility effects would enter.

Boeing Smart Rotor Full-scale Wind Tunnel Test Data Report

NASA Technical Reports Server (NTRS)

Kottapalli, Sesi; Hagerty, Brandon; Salazar, Denise

2016-01-01

A full-scale helicopter smart material actuated rotor technology (SMART) rotor test was conducted in the USAF National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel at NASA Ames. The SMART rotor system is a five-bladed MD 902 bearingless rotor with active trailing-edge flaps. The flaps are actuated using piezoelectric actuators. Rotor performance, structural loads, and acoustic data were obtained over a wide range of rotor shaft angles of attack, thrust, and airspeeds. The primary test objective was to acquire unique validation data for the high-performance computing analyses developed under the Defense Advanced Research Project Agency (DARPA) Helicopter Quieting Program (HQP). Other research objectives included quantifying the ability of the on-blade flaps to achieve vibration reduction, rotor smoothing, and performance improvements. This data set of rotor performance and structural loads can be used for analytical and experimental comparison studies with other full-scale rotor systems and for analytical validation of computer simulation models. The purpose of this final data report is to document a comprehensive, highquality data set that includes only data points where the flap was actively controlled and each of the five flaps behaved in a similar manner.
Tests of Full-Scale Helicopter Rotors at High Advancing Tip Mach Numbers and Advance Ratios

NASA Technical Reports Server (NTRS)

Biggers, James C.; McCloud, John L., III; Stroub, Robert H.

2015-01-01

As a continuation of the studies of reference 1, three full-scale helicopter rotors have been tested in the Ames Research Center 40- by SO-foot wind tunnel. All three of them were two-bladed, teetering rotors. One of the rotors incorporated the NACA 0012 airfoil section over the entire length of the blade. This rotor was tested at advance ratios up to 1.05. Both of the other rotors were tapered in thickness and incorporated leading-edge camber over the outer 20 percent of the blade radius. The larger of these rotors was tested at advancing tip Mach numbers up to 1.02. Data were obtained for a wide range of lift and propulsive force, and are presented without discussion.
Wind-tunnel investigation of an N.A.C.A. 23012 airfoil with two arrangements of a wide-chord slotted flap

NASA Technical Reports Server (NTRS)

Harris, Thomas A

1939-01-01

An investigation has been made in the N.A.C.A. 7- by 10-foot wind tunnel of a large-chord N.A.C.A. 23012 airfoil with several arrangements of a 40-percent-chord slotted flap to determine the section aerodynamic characteristics of the airfoil as affected by slot shape, flap location, and flap deflection. The flap positions for maximum lift, the polar for arrangements considered favorable for take-off and climb, and the complete section aerodynamic characteristics for selected optimum arrangements were determined. A discussion is given of the relative merits of the various arrangements. A comparison is made of slotted flaps of different chords on the N.A.C.A. 23012 airfoil. The best 40-percent-chord slotted flap is only slightly superior to the 25-percent-chord slotted flap from considerations of maximum lift coefficient and low drag for take-off and initial climb.
A Study of Acoustic Reflections in Full-Scale Rotor Low Frequency Noise Measurements Acquired in Wind Tunnels

NASA Technical Reports Server (NTRS)

Barbely, Natasha L.; Sim, Ben W.; Kitaplioglu, Cahit; Goulding, Pat, II

2010-01-01

Difficulties in obtaining full-scale rotor low frequency noise measurements in wind tunnels are addressed via residual sound reflections due to non-ideal anechoic wall treatments. Examples illustrated with the Boeing-SMART rotor test in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel facility demonstrated that these reflections introduced distortions in the measured acoustic time histories that are not representative of free-field rotor noise radiation. A simplified reflection analysis, based on the method of images, is used to examine the sound measurement quality in such "less-than-anechoic" environment. Predictions of reflection-adjusted acoustic time histories are qualitatively shown to account for some of the spurious fluctuations observed in wind tunnel noise measurements
New insights on the interaction between atmospheric flow and a full-scale 2.5 MW wind turbine

NASA Astrophysics Data System (ADS)

Chamorro, L. P.; Lee, S.; Olsen, D.; Milliren, C.; Marr, J.; Arndt, R.; Sotiropoulos, F.

2012-12-01

Power fluctuations and fatigue loads are among the most significant problems that wind turbines face throughout their lifetime. Atmospheric turbulence is the common driving mechanism that triggers instabilities on these quantities. Reducing the effects of the fluctuating flow on wind turbines is quite challenging due to the wide variety of length scales present in the boundary layer flow. Each group of these scales, which range from the order of a millimeter to kilometer and larger, plays a characteristic and distinctive role on the performance and structural reliability of wind turbines. This study seeks to contribute toward the understanding on the complex scale-to-scale interaction between wind turbine and flow turbulence. Novel insights into the physical mechanisms that govern the flow/turbine interaction will be discussed. To tackle the problem, we investigate the unsteady behavior of a full-scale 2.5 MW wind turbine under nearly neutral thermal stratification. The study is performed in the Eolos Wind Energy Research Field Station of the University of Minnesota. An instrumented 130 meter meteorological tower located upstream of a Clipper Liberty C96 wind turbine is used to characterize the turbulent flow and atmospheric conditions right upstream of the wind turbine. High resolution and synchronous measurements of the approach wind velocity at several heights, turbine power and strain at the tower foundation are used to determine the scale-to-scale interaction between flow and the wind turbine performance and its physical structure. The spectral distribution of the fluctuating turbine power and instantaneous stresses will be discussed in detail. Characteristic length scales playing a key role on the dynamics of the wind turbine as well as the distinctive effects of flow coherent motions and strong intermittent gusts will also be addressed. Funding was provided by the U.S. Department of Energy (DE-EE0002980) and Xcel Energy through the Renewable Development Fund
Construction of the 40x80 Foot Wind Tunnel at Ames.

NASA Image and Video Library

1943-07-07

Looking South from inside the diffuser of the 40x80 foot wind tunnel at NACA's Ames Research Center. Construction began in late 1941, the mammoth construction task sorely taxing the resources of the new center. Two and a half years later, in dune 1944, the 40 x 80-foot full-scale tunnel went into operation.
Aeroelastic Deformation: Adaptation of Wind Tunnel Measurement Concepts to Full-Scale Vehicle Flight Testing

NASA Technical Reports Server (NTRS)

Burner, Alpheus W.; Lokos, William A.; Barrows, Danny A.

2005-01-01

The adaptation of a proven wind tunnel test technique, known as Videogrammetry, to flight testing of full-scale vehicles is presented. A description is presented of the technique used at NASA's Dryden Flight Research Center for the measurement of the change in wing twist and deflection of an F/A-18 research aircraft as a function of both time and aerodynamic load. Requirements for in-flight measurements are compared and contrasted with those for wind tunnel testing. The methodology for the flight-testing technique and differences compared to wind tunnel testing are given. Measurement and operational comparisons to an older in-flight system known as the Flight Deflection Measurement System (FDMS) are presented.
Aerodynamic Characteristics at High Speeds of Full-Scale Propellers having Different Shank Designs

NASA Technical Reports Server (NTRS)

Maynard, Julian D.

1947-01-01

Tests of two 10-foot-diameter two-blade propellers which differed only in shank design have been made in the Langley 16-foot high-speed tunnel. The propellers are designated by their blade design numbers, NACA 10-(5)(08)-03, which had aerodynamically efficient airfoil shank sections, and NACA l0-(5)(08)-03R which had thick cylindrical shank sections typical of conventiona1 blades, The propellers mere tested on a 2000-horsepower dynamometer through a range of blade-angles from 20deg to 55deg at various rotational speeds and at airspeeds up to 496 miles per hour. The resultant tip speeds obtained simulate actual flight conditions, and the variation of air-stream Mach number with advance ratio is within the range of full-scale constant-speed propeller operation. Both propellers were very efficient, the maximum envelope efficiency being approximately 0,95 for the NACA 10-(5)(08)-03 propeller and about 5 percent less for the NACA 10-(5)(08)-03R propeller. Based on constant power and rotational speed, the efficiency of the NACA 10-(05)(08)-03 propeller was from 2.8 to 12 percent higher than that of the NACA 10-(5)(08)-03R propeller over a range of airspeeds from 225 to 450 miles per hour. The loss in maximum efficiency at the design blade angle for the NACA 10-(5)(08)-03 and 10-(5)(08)-03R propellers vas about 22 and 25 percent, respectively, for an increase in helical tip Mach number from 0.70 to 1.14.
NACA Groundbreaking Ceremony

NASA Technical Reports Server (NTRS)

1953-01-01

The NACA High-Speed Flight Research Station, had initially been subordinate to the Langley Memorial Aeronautical Laboratory near Hampton, Virginia, but as the flight research in the Mojave Desert increasingly proved its worth after 1946, it made sense to make the Flight Research Station a separate entity reporting directly to the headquarters of the National Advisory Committee for Aeronautics. But an autonomous center required all the trappings of a major research facility, including good quarters. With the adoption of the Edwards 'Master Plan,' the Air Force had committed itself to moving from its old South Base to a new location midway between the South and North Bases. The NACA would have to move also--so why not take advantage of the situation and move into a full-blown research facility. The Air Force issued a lease to NACA for a location on the northwestern shore of the Roger Dry Lake. Construction started on the NACA station in early February 1953. On a windy day, January 27, 1953, at a groundbreaking ceremony stood left to right: Gerald Truszynski, Head of Instrumentation Division; Joseph Vensel, Head of the Operations Branch; Walter Williams, Head of the Station, scooping the first shovel full of dirt; Marion Kent, Head of Personnel; and California state official Arthur Samet.
Full-scale wind-tunnel tests of high-lift system modifications on a carrier based fighter aircraft

NASA Technical Reports Server (NTRS)

Meyn, Larry A.; Zell, Peter T.; Hagan, John L.; Schoch, David

1993-01-01

Modifications to the high-lift system of a full-scale F/A-I8A were tested in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at the NASA Ames Research Center in Moffett Field, California. The objective was to measure the effect of simple modifications on the aerodynamic performance of the high-lift system. The modifications included the placement of a straight fairing in the shroud cove above the trailing-edge flap and the addition of seals to prevent air leakage through the hinge lines of the leading-edge flap, the trailing-edge shroud, and the wing fold. The test was carried out on an actual F/A-18A with it's flaps deployed in the landing approach configuration. The angle of attack ranged from 0 to 16 degrees and the wind speed was 100 knots. At an angle of attack of 8 degrees, the trimmed lift coefficient was improved by 0.09 with all wing seals in place. This corresponds to a reduction in the approach speed for the F/A-I8A of about 5 knots. The seal along the wing fold hinge, a feature present on many naval aircraft, provided one third of the total increment in trimmed lift. A comparison of the full-scale wind-tunnel results with those obtained from flight test is also presented.
An experimental low Reynolds number comparison of a Wortmann FX67-K170 airfoil, a NACA 0012 airfoil and a NACA 64-210 airfoil in simulated heavy rain

NASA Technical Reports Server (NTRS)

Craig, Anthony P.; Hansman, R. John

1987-01-01

Wind tunnel experiments were conducted on Wortmann FX67-K170, NACA 0012, and NACA 64-210 airfoils at rain rates of 1000 mm/hr and Reynolds numbers of 310,000 to compare the aerodynamic performance degradation of the airfoils and to attempt to identify the various mechanisms which affect performance in heavy rain conditions. Lift and drag were measured in dry and wet conditions, a variety of flow visualization techniques were employed, and a computational code which predicted airfoil boundary layer behavior was used. At low angles of attack, the lift degradation in wet conditions varied significantly between the airfoils. The Wortmann section had the greatest overall lift degradation and the NACA 64-210 airfoil had the smallest. At high angles of attack, the NACA 64-210 and 0012 airfoils had improved aerodynamic performance in rain conditions due to an apparent reduction of the boundry layer separation. Performance degradation in heavy rain for all three airfoils at low angles of attack could be emulated by forced boundary layer transition near the leading edge. The secondary effect occurs at time scales consistent with top surface water runback times. The runback layer is thought to effectively alter the airfoil geometry. The severity of the performance degradation for the airfoils varied. The relative differences appeared to be related to the susceptibility of each airfoil to premature boundary layer transition.
Vultee YA–31C Vengeance at the NACA

NASA Image and Video Library

1945-03-21

A Bell P-39 Airacobra in the NACA Aircraft Engine Research Laboratory’s Icing Research Tunnel for a propeller deicing study. The tunnel, which began operation in June 1944, was built to study the formation of ice on aircraft surfaces and methods of preventing or eradicating that ice. Ice buildup adds extra weight to aircraft, effects aerodynamics, and sometimes blocks airflow through engines. NACA design engineers added the Icing Research Tunnel to the new AERL’s original layout to take advantage of the massive refrigeration system being constructed for the Altitude Wind Tunnel. The Icing Research Tunnel is a closed-loop atmospheric wind tunnel with a 6- by 9-foot test section. The tunnel can produce speeds up to 300 miles per hour and temperatures from about 30 to -45⁰ F. During World War II AERL researchers analyzed different ice protection systems for propeller, engine inlets, antennae, and wings in the icing tunnel. The P-39 was a vital low-altitude pursuit aircraft of the US during the war. NACA investigators investigated several methods of preventing ice buildup on the P-39’s propeller, including the use of internal and external electrical heaters, alcohol, and hot gases. They found that continual heating of the blades expended more energy than the aircraft could supply, so studies focused on intermittent heating. The results of the wind tunnel investigations were then compared to actual flight tests on aircraft.
Facilities and Methods Used in Full-scale Airplane Crash-fire Investigation

NASA Technical Reports Server (NTRS)

Black, Dugald O.

1952-01-01

The facilities and the techniques employed in the conduct of full scale airplane crash-fire studies currently being conducted at the NACA Lewis laboratory are discussed herein. This investigation is part of a comprehensive study of the airplane crash-fire problem. The crash configuration chosen, the general physical layout of the crash site, the test methods, the instrumentation, the data-recording systems, and the post-crash examination procedure are described
Wake losses from averaged and time-resolved power measurements at full scale wind turbines

NASA Astrophysics Data System (ADS)

Castellani, Francesco; Astolfi, Davide; Mana, Matteo; Becchetti, Matteo; Segalini, Antonio

2017-05-01

This work deals with the experimental analysis of wake losses fluctuations at full-scale wind turbines. The test case is a wind farm sited on a moderately complex terrain: 4 turbines are installed, having 2 MW of rated power each. The sources of information are the time-resolved data, as collected from the OPC server, and the 10-minutes averaged SCADA data. The objective is to compare the statistical distributions of wake losses for far and middle wakes, as can be observed through the “fast” lens of time-resolved data, for certain selected test-case time series, and through the “slow” lens of SCADA data, on a much longer time basis that allow to set the standards of the mean wake losses along the wind farm. Further, time-resolved data are used for an insight into the spectral properties of wake fluctuations, highlighting the role of the wind turbine as low-pass filter. Summarizing, the wind rose, the layout of the site and the structure of the data sets at disposal allow to study middle and far wake behavior, with a “slow” and “fast” perspective.
Propeller propulsion integration, phase 1. [conducted in langley 30 by 60 foot full scale wind tunnel

NASA Technical Reports Server (NTRS)

Bennett, G.; Koenig, K.; Miley, S. J.; Mcwhorter, J.; Wells, G.

1981-01-01

A bibliography was compiled of all readily available sources of propeller analytical and experimental studies conducted during the 1930 through 1960 period. A propeller test stand was developed for the measurement of thrust and torque characteristics of full scale general aviation propellers and installed in the LaRC 30 x 60 foot full scale wind tunnel. A tunnel entry was made during the January through February 1980 period. Several propellers were tested, but unforseen difficulties with the shaft thrust torque balance severely degraded the data quality.
Characterizing the Influence of Abstraction in Full-Scale Wind Turbine Nacelle Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schkoda, Ryan; Bibo, Amin; Guo, Yi

2016-08-21

In recent years, there has been a growing interest in full-scale wind turbine nacelle testing to complement individual component testing. As a result, several wind turbine nacelle test benches have been built to perform such testing with the intent of loading the integrated components as they are in the field. However, when mounted on a test bench the nacelle is not on the top of a tower and does not have blades attached to it - this is a form of abstraction. This paper aims to quantify the influence of such an abstraction on the dynamic response of the nacellemore » through a series of simulation case studies. The responses of several nacelle components are studied including the main bearing, main shaft, gearbox supports, generator, and yaw bearing interface. Results are presented to highlight the differences in the dynamic response of the nacelle caused by the abstraction. Additionally, the authors provide recommendations for mitigating the effects of the abstraction.« less
A restored NACA P-51D Mustang in flight

NASA Image and Video Library

2000-09-15

A white plate on the top of the wing of a restored National Advisory Committee for Aeronautics (NACA) P-51D Mustang mounts scale airfoil shapes as used by the NACA in the late 1940s for high-speed research. This former NACA testbed Mustang was rebuilt by John Muszala for Bill Allmon of Las Vegas, Nevada, who has been flying it since 1998. Allmon flew the vintage fighter to NASA's Dryden Flight Research Center at Edwards, California, Sept. 15, 2000 for a reunion of former NACA employees.
What scaling means in wind engineering: Complementary role of the reduced scale approach in a BLWT and the full scale testing in a large climatic wind tunnel

NASA Astrophysics Data System (ADS)

Flamand, Olivier

2017-12-01

Wind engineering problems are commonly studied by wind tunnel experiments at a reduced scale. This introduces several limitations and calls for a careful planning of the tests and the interpretation of the experimental results. The talk first revisits the similitude laws and discusses how they are actually applied in wind engineering. It will also remind readers why different scaling laws govern in different wind engineering problems. Secondly, the paper focuses on the ways to simplify a detailed structure (bridge, building, platform) when fabricating the downscaled models for the tests. This will be illustrated by several examples from recent engineering projects. Finally, under the most severe weather conditions, manmade structures and equipment should remain operational. What “recreating the climate” means and aims to achieve will be illustrated through common practice in climatic wind tunnel modelling.
Experimental study of improved HAWT performance in simulated natural wind by an active controlled multi-fan wind tunnel

NASA Astrophysics Data System (ADS)

Toshimitsu, Kazuhiko; Narihara, Takahiko; Kikugawa, Hironori; Akiyoshi, Arata; Kawazu, Yuuya

2017-04-01

The effects of turbulent intensity and vortex scale of simulated natural wind on performance of a horizontal axis wind turbine (HAWT) are mainly investigated in this paper. In particular, the unsteadiness and turbulence of wind in Japan are stronger than ones in Europe and North America in general. Hence, Japanese engineers should take account of the velocity unsteadiness of natural wind at installed open-air location to design a higher performance wind turbine. Using the originally designed five wind turbines on the basis of NACA and MEL blades, the dependencies of the wind frequency and vortex scale of the simulated natural wind are presented. As the results, the power coefficient of the newly designed MEL3-type rotor in the simulated natural wind is 130% larger than one in steady wind.
Static Aeroelastic Scaling and Analysis of a Sub-Scale Flexible Wing Wind Tunnel Model

NASA Technical Reports Server (NTRS)

Ting, Eric; Lebofsky, Sonia; Nguyen, Nhan; Trinh, Khanh

2014-01-01

This paper presents an approach to the development of a scaled wind tunnel model for static aeroelastic similarity with a full-scale wing model. The full-scale aircraft model is based on the NASA Generic Transport Model (GTM) with flexible wing structures referred to as the Elastically Shaped Aircraft Concept (ESAC). The baseline stiffness of the ESAC wing represents a conventionally stiff wing model. Static aeroelastic scaling is conducted on the stiff wing configuration to develop the wind tunnel model, but additional tailoring is also conducted such that the wind tunnel model achieves a 10% wing tip deflection at the wind tunnel test condition. An aeroelastic scaling procedure and analysis is conducted, and a sub-scale flexible wind tunnel model based on the full-scale's undeformed jig-shape is developed. Optimization of the flexible wind tunnel model's undeflected twist along the span, or pre-twist or wash-out, is then conducted for the design test condition. The resulting wind tunnel model is an aeroelastic model designed for the wind tunnel test condition.

Gravo-Aeroelastic Scaling for Extreme-Scale Wind Turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fingersh, Lee J; Loth, Eric; Kaminski, Meghan

2017-06-09

A scaling methodology is described in the present paper for extreme-scale wind turbines (rated at 10 MW or more) that allow their sub-scale turbines to capture their key blade dynamics and aeroelastic deflections. For extreme-scale turbines, such deflections and dynamics can be substantial and are primarily driven by centrifugal, thrust and gravity forces as well as the net torque. Each of these are in turn a function of various wind conditions, including turbulence levels that cause shear, veer, and gust loads. The 13.2 MW rated SNL100-03 rotor design, having a blade length of 100-meters, is herein scaled to the CART3more » wind turbine at NREL using 25% geometric scaling and blade mass and wind speed scaled by gravo-aeroelastic constraints. In order to mimic the ultralight structure on the advanced concept extreme-scale design the scaling results indicate that the gravo-aeroelastically scaled blades for the CART3 are be three times lighter and 25% longer than the current CART3 blades. A benefit of this scaling approach is that the scaled wind speeds needed for testing are reduced (in this case by a factor of two), allowing testing under extreme gust conditions to be much more easily achieved. Most importantly, this scaling approach can investigate extreme-scale concepts including dynamic behaviors and aeroelastic deflections (including flutter) at an extremely small fraction of the full-scale cost.« less
Monitoring of Wind Turbine Gearbox Condition through Oil and Wear Debris Analysis: A Full-Scale Testing Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, Shuangwen

Despite the wind industry's dramatic development during the past decade, it is still challenged by premature turbine subsystem/component failures, especially for turbines rated above 1 MW. Because a crane is needed for each replacement, gearboxes have been a focal point for improvement in reliability and availability. Condition monitoring (CM) is a technique that can help improve these factors, leading to reduced turbine operation and maintenance costs and, subsequently, lower cost of energy for wind power. Although technical benefits of CM for the wind industry are normally recognized, there is a lack of published information on the advantages and limitations ofmore » each CM technique confirmed by objective data from full-scale tests. This article presents first-hand oil and wear debris analysis results obtained through tests that were based on full-scale wind turbine gearboxes rated at 750 kW. The tests were conducted at the 2.5-MW dynamometer test facility at the National Wind Technology Center at the National Renewable Energy Laboratory. The gearboxes were tested in three conditions: run-in, healthy, and damaged. The investigated CM techniques include real-time oil condition and wear debris monitoring, both inline and online sensors, and offline oil sample and wear debris analysis, both onsite and offsite laboratories. The reported results and observations help increase wind industry awareness of the benefits and limitations of oil and debris analysis technologies and highlight the challenges in these technologies and other tribological fields for the Society of Tribologists and Lubrication Engineers and other organizations to help address, leading to extended gearbox service life.« less
Effect of High-Fidelity Ice Accretion Simulations on the Performance of a Full-Scale Airfoil Model

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Bragg, Michael B.; Addy, Harold E., Jr.; Lee, Sam; Moens, Frederic; Guffond, Didier

2010-01-01

The simulation of ice accretion on a wing or other surface is often required for aerodynamic evaluation, particularly at small scale or low-Reynolds number. While there are commonly accepted practices for ice simulation, there are no established and validated guidelines. The purpose of this article is to report the results of an experimental study establishing a high-fidelity, full-scale, iced-airfoil aerodynamic performance database. This research was conducted as a part of a larger program with the goal of developing subscale aerodynamic simulation methods for iced airfoils. Airfoil performance testing was carried out at the ONERA F1 pressurized wind tunnel using a 72-in. (1828.8-mm) chord NACA 23012 airfoil over a Reynolds number range of 4.5x10(exp 6) to 16.0 10(exp 6) and a Mach number range of 0.10 to 0.28. The high-fidelity, ice-casting simulations had a significant impact on the aerodynamic performance. A spanwise-ridge ice shape resulted in a maximum lift coefficient of 0.56 compared to the clean value of 1.85 at Re = 15.9x10(exp 6) and M = 0.20. Two roughness and streamwise shapes yielded maximum lift values in the range of 1.09 to 1.28, which was a relatively small variation compared to the differences in the ice geometry. The stalling characteristics of the two roughness and one streamwise ice simulation maintained the abrupt leading-edge stall type of the clean NACA 23012 airfoil, despite the significant decrease in maximum lift. Changes in Reynolds and Mach number over the large range tested had little effect on the iced-airfoil performance.
NACA Wartime Safety Poster

NASA Image and Video Library

1945-04-21

One of many safety posters produced by NACA artists during World War II. The Aircraft Engine Research Laboratory established a Safety Office in 1942 to coordinate and oversee safety-related activities. The lab struggled to maintain a full staff during the war when military research projects were at a peak. NACA management mandated six-day work weeks without overtime and the elimination of holidays. As such, workplace injuries were a serious threat to maintaining productivity needed to sustain the military’s aeronautics efforts.
Characterizing the Influence of Abstraction in Full-Scale Wind Turbine Nacelle Testing: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schkoda, Ryan; Bibo, Amin; Guo, Yi

2016-08-01

In recent years, there has been a growing interest in full-scale wind turbine nacelle testing to complement individual component testing. As a result, several wind turbine nacelle test benches have been built to perform such testing with the intent of loading the integrated components as they are in the field. However, when mounted on a test bench the nacelle is not on the top of a tower and does not have blades attached to it--this is a form of abstraction. This paper aims to quantify the influence of such an abstraction on the dynamic response of the nacelle through amore » series of simulation case studies. The responses of several nacelle components are studied including the main bearing, main shaft, gearbox supports, generator, and yaw bearing interface. Results are presented to highlight the differences in the dynamic response of the nacelle caused by the abstraction. Additionally, the authors provide recommendations for mitigating the effects of the abstraction.« less
Lunar Excursion Model in Full Scale Wind Tunnel. Apollo Project. Bell Lunar Landing Training Vehicle (LLTV)

NASA Image and Video Library

1969-01-16

Concept model of the Lunar Excursion Module tested in the Full-Scale wind tunnel. -- Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, (Washington: NASA, 1995), p. 356.-L69-670 Bell Lunar Landing Training Vehicle (LLTV): Following the crash of a sister Lunar Landing Training Vehicle at Ellington Field in Houston, Texas, the LLTV NASA 952 was sent from Houston to Langley for tests in the 30 x 60 Full Scale Tunnel. The LLTV was returned to Houston for further training use a short time later. NASA 952 is now on exhibit at the Johnson Space Center in Houston, Texas.
7. VIEW WEST OF SCALE ROOM IN FULLSCALE WIND TUNNEL; ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VIEW WEST OF SCALE ROOM IN FULL-SCALE WIND TUNNEL; SCALES ARE USED TO MEASURE FORCES ACTING ON MODEL AIRCRAFT SUSPENDED ABOVE. - NASA Langley Research Center, Full-Scale Wind Tunnel, 224 Hunting Avenue, Hampton, Hampton, VA
Comparative wind tunnel test at high Reynolds numbers of NACA 64 621 airfoils with two aileron configurations

NASA Technical Reports Server (NTRS)

Gregorek, G. M.

1995-01-01

An experimental program to measure the aerodynamic characteristics of the NACA 64-621 airfoil when equipped with plain ailerons of 0.38 chord and 0.30 chord and with 0.38 chord balanced aileron has been conducted in the pressurized O.S.U. 6 x 12 ft High Reynolds Number Wind Tunnel. Surface pressures were measured and integrated to yield lift and pressure drag coefficients for angles of attack from -3 to +42 deg and for selected aileron deflections from 0 to -90 deg at nominal Mach and Reynolds numbers of 0.25 and 5 x 10(exp 6). When resolved into thrust coefficient for wind turbine aerodynamic control applications, the data indicated the anticipated decrease in thrust coefficient with negative aileron deflection at low angles of attack; however, as angle of attack increased, thrust coefficients eventually became positive. All aileron configurations, even at -90 deg deflections showed this trend. Hinge moments for each configuration complete the data set.
Full-scale S-76 rotor performance and loads at low speeds in the NASA Ames 80- by 120-Foot Wind Tunnel. Vol. 1

NASA Technical Reports Server (NTRS)

Shinoda, Patrick M.

1996-01-01

A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. Rotor performance and loads data were obtained over a wide range of rotor shaft angles-of-attack and thrust conditions at tunnel speeds ranging from 0 to 100 kt. The primary objectives of this test were (1) to acquire forward flight rotor performance and loads data for comparison with analytical results; (2) to acquire S-76 forward flight rotor performance data in the 80- by 120-Foot Wind Tunnel to compare with existing full-scale 40- by 80-Foot Wind Tunnel test data that were acquired in 1977; (3) to evaluate the acoustic capability of the 80- by 120- Foot Wind Tunnel for acquiring blade vortex interaction (BVI) noise in the low speed range and compare BVI noise with in-flight test data; and (4) to evaluate the capability of the 80- by 120-Foot Wind Tunnel test section as a hover facility. The secondary objectives were (1) to evaluate rotor inflow and wake effects (variations in tunnel speed, shaft angle, and thrust condition) on wind tunnel test section wall and floor pressures; (2) to establish the criteria for the definition of flow breakdown (condition where wall corrections are no longer valid) for this size rotor and wind tunnel cross-sectional area; and (3) to evaluate the wide-field shadowgraph technique for visualizing full-scale rotor wakes. This data base of rotor performance and loads can be used for analytical and experimental comparison studies for full-scale, four-bladed, fully articulated rotor systems. Rotor performance and structural loads data are presented in this report.
Missile on Display at the 1957 NACA Lewis Inspection

NASA Image and Video Library

1957-10-21

A researcher examines a model being installed in the test section of the 10- by 10-Foot Supersonic Wind Tunnel during the 1957 Inspection of the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The NACA held its annual Inspection at one of its three research laboratories. Representatives from the military, aeronautical industry, universities, and the press were invited to the laboratory to be briefed on the NACA’s latest research efforts and tour the state- of- the- art test facilities. Over 1700 people visited the NACA Lewis in Cleveland, Ohio during the October 7 - 10, 1957 Inspection. NACA researchers Leonard Obery, seen here, James Connors, Leonard, Stitt, David Bowditch gave presentations on high Mach number turbojets at the 10- by 10 tunnel. It had been only 15 years since a jet aircraft had first flown in the US. Since then the sound barrier had been broken and speeds of Mach 2.5 had been achieved. In the late 1950s NACA researchers sought to create an engine that could achieve Mach 4. This type of engine would require an extremely long inlet and nozzle which would have to be capable of adjusting their diameter for different speeds. A Mach 4 engine would require new composite materials to withstand the severe conditions, modified airframes to hold the longer engines, and high temperature seals and lubricants. The 10- by 10-foot tunnel, which had only been in operation for a year and a half, would play a critical role in these studies. NACA researchers at other facilities discussed high energy aircraft fuels and rocket propellants, aircraft noise reduction, hypersonic flight, nuclear propulsion, and high temperature materials.
NACA documents database project

NASA Technical Reports Server (NTRS)

Smith, Ruth S.

1991-01-01

The plan to get all the National Advisory Committee on Aeronautics (NACA) collection online, with quality records, led to the NACA Documents Data base Project. The project has a two fold purpose: (1) to develop the definitive bibliography of NACA produced and/or held documents; and (2) to make that bibliography and the associated documents available to the aerospace community. This study supports the first objective by providing an analysis of the NACA collection and its bibliographic records, and supports the second objective by defining the NACA archive and recommending methodologies for meeting the project objectives.
On the Full-range β Dependence of Ion-scale Spectral Break in the Solar Wind Turbulence

NASA Astrophysics Data System (ADS)

Wang, Xin; Tu, Chuanyi; He, Jiansen; Wang, Linghua

2018-04-01

The power spectrum of magnetic fluctuations has a break at the high-frequency end of the inertial range. Beyond this break, the spectrum becomes steeper than the Kolmogorov law f ‑5/3. The break frequency was found to be associated with plasma beta (β). However, the full-range β dependence of the ion-scale spectral break has not been presented before in observational studies. Here we show the continuous variation of the break frequency on full-range β in the solar wind turbulence. By using measurements from the WIND and Ulysses spacecraft, we show the break frequency (f b ) normalized, respectively, by the frequencies corresponding to ion inertial length (f di ), ion gyroradius ({f}ρ i), and cyclotron resonance scale (f ri ) as a function of β for 1306 intervals. Their β values spread from 0.005 to 20, which nearly covers the full β range of the observed solar wind turbulence. It is found that {f}b/{f}{di} ({f}b/{f}ρ i) generally decreases (increases) with β, while {f}b/{f}{ri} is nearly a constant. We perform a linear fit on the statistical result, and obtain the empirical formulas {f}b/{f}{di}∼ {β }-1/4, {f}b/{f}ρ i∼ {β }1/4, and {f}b/{f}{ri}∼ 0.90 to describe the relation between f b and β. We also compare our observations with a numerical simulation and the prediction by ion cyclotron resonance theory. Our result favors the idea that the cyclotron resonance is an important mechanism for energy dissipation at the spectral break. When β ≪ 1 and β ≫ 1, the break at f di and {f}ρ i may also be associated with other processes.
Effect of Exit-Slot Position and Opening on the Available Cooling Pressure for NACA Nose-Slot Cowlings

NASA Technical Reports Server (NTRS)

Stickle, George W; Naiman, Irven; Crigler, John L

1940-01-01

Report presents the results of an investigation of full-scale nose-slot cowlings conducted in the NACA 20-foot wind tunnel to furnish information on the pressure drop available for cooling. Engine conductances from 0 to 0.12 and exit-slot conductances from 0 to 0.30 were covered. Two basic nose shapes were tested to determine the effect of the radius of curvature of the nose contour; the nose shape with the smaller radius of curvature gave the higher pressure drop across the engine. The best axial location of the slot for low-speed operation was found to be in the region of maximum negative pressure for the basic shape for the particular operating condition. The effect of the pressure operating condition on the available cooling pressure is shown.
NACA Conference on Helicopters

DTIC Science & Technology

1954-05-01

Louis S., Jr.: Summary of Airfoil Data. NACA Rep. 824, 1945. (Supersedes NACA WR L-560.) 2. Loftin, Laurence K., Jr., and Smith , Hamilton, A...F., and Smith , Hamilton A.: Aerodynamic Character- istics of the NACA 8-H-12 Airfoil Section at Six Reynold Numbers From 1.8 x 1u6 to 11.0 X 106...NACA TN 1998, 1949. 4. Smith , Hamilton A., and Schaefer, Raymond F.: Aerodynamic Character- 0 istics at Reynolds Numbers of 3.0 X 106 and 6.0 x 106 of
Complete NACA Muroc Staff of 1950, in front of original NACA building

NASA Technical Reports Server (NTRS)

1950-01-01

This group photo of National Advisory Committee for Aeronautics (NACA) employees was taken in 1950 in front of the NACA research building on South Base at Edwards Air Force Base, California. The team that had been established at Muroc Army Air Field in the later part of 1946 had grown to about 13 members at the beginning of 1947. In September of 1947 the group became known as the NACA Muroc Flight Test Unit with a complement of 27 employees by January 1948. In February 1948 the name of the base changed to Muroc Air Force Base and in 1949 would change again to Edwards Air Force Base. In November 1949 the NACA Muroc Flight Test Unit became the NACA High-Speed Flight Research Station. In January 1950 there were 132 employees with those numbers increasing to 196 by January 1952.
The Design of Low-Turbulence Wind Tunnels

NASA Technical Reports Server (NTRS)

Dryden, Hugh L; Abbott, Ira H

1949-01-01

Within the past 10 years there have been placed in operation in the United States four low-turbulence wind tunnels of moderate cross-sectional area and speed, one at the National Bureau of Standards, two at the NACA Langley Laboratory, and one at the NACA Ames Laboratory. This paper reviews briefly the state of knowledge and those features which make possible the attainment of low turbulence in wind tunnels. Specific applications to two wind tunnels are described.
Sub-Scale Orion Parachute Test Results from the National Full-Scale Aerodynamics Complex 80- By 120-ft Wind Tunnel

NASA Technical Reports Server (NTRS)

Anderson, Brian P.; Greathouse, James S.; Powell, Jessica M.; Ross, James C.; Schairer, Edward T.; Kushner, Laura; Porter, Barry J.; Goulding, Patrick W., II; Zwicker, Matthew L.; Mollmann, Catherine

2017-01-01

A two-week test campaign was conducted in the National Full-Scale Aerodynamics Complex 80 x 120-ft Wind Tunnel in support of Orion parachute pendulum mitigation activities. The test gathered static aerodynamic data using an instrumented, 3-tether system attached to the parachute vent in combination with an instrumented parachute riser. Dynamic data was also gathered by releasing the tether system and measuring canopy performance using photogrammetry. Several canopy configurations were tested and compared against the current Orion parachute design to understand changes in drag performance and aerodynamic stability. These configurations included canopies with varying levels and locations of geometric porosity as well as sails with increased levels of fullness. In total, 37 runs were completed for a total of 392 data points. Immediately after the end of the testing campaign a down-select decision was made based on preliminary data to support follow-on sub-scale air drop testing. A summary of a more rigorous analysis of the test data is also presented.
NACA's Lockheed F-94B Starfire with Audio Recording Devices

NASA Image and Video Library

1957-07-21

A Lockheed F-94B Starfire being equipped with an audio recording machine and sensors at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The NACA was investigating the acoustic effects caused by the engine’s nozzle and the air flowing along the fuselage. Airline manufacturers would soon be introducing jet engines on their passenger aircraft, and there was concern regarding the noise levels for both the passengers and public on the ground. NACA Lewis conducted a variety of noise reduction studies in its wind tunnels, laboratories, and on a F2H-2B Banshee aircraft. The F2H-2B Banshee’s initial test flights in 1955 and 1956 measured the noise emanating directly from airflow over the aircraft’s surfaces, particularly the wings. This problem was particularly pronounced at high subsonic speeds. The researchers found the majority of the noise occurred in the low and middle octaves. These investigations were enhanced with a series of flights using the F-94B Starfire. The missions measured wall-pressure, turbulence fluctuations, and mean velocity profiles. Mach 0.3 to 0.8 flights were flown at altitudes of 10,000, 20,000, and 30,000 feet with microphones mounted near the forward fuselage and on a wing. The results substantiated the wind tunnel findings. This photograph shows the tape recorder being installed in the F-94B’s nose.
Aerial View of NACA's Lewis Flight Propulsion Research Laboratory

NASA Image and Video Library

1946-05-21

The National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory in Cleveland, Ohio as seen from the west in May 1946. The Cleveland Municipal Airport is located directly behind. The laboratory was built in the early 1940s to resolve problems associated with aircraft engines. The initial campus contained seven principal buildings: the Engine Research Building, hangar, Fuels and Lubricants Building, Administration Building, Engine Propeller Research Building, Altitude Wind Tunnel, and Icing Research Tunnel. These facilities and their associated support structures were located within an area occupying approximately one-third of the NACA’s property. After World War II ended, the NACA began adding new facilities to address different problems associated with the newer, more powerful engines and high speed flight. Between 1946 and 1955, four new world-class test facilities were built: the 8- by 6-Foot Supersonic Wind Tunnel, the Propulsion Systems Laboratory, the Rocket Engine Test Facility, and the 10- by 10-Foot Supersonic Wind Tunnel. These large facilities occupied the remainder of the NACA’s semicircular property. The Lewis laboratory expanded again in the late 1950s and early 1960s as the space program commenced. Lewis purchased additional land in areas adjacent to the original laboratory and acquired a large 9000-acre site located 60 miles to the west in Sandusky, Ohio. The new site became known as Plum Brook Station.
13. Photocopy of photograph (original in the Langley Research Center ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. Photocopy of photograph (original in the Langley Research Center Archives, Hampton, VA LaRC) (NACA 4655) VIEW LOOKING NORTH AT THE FULL-SCALE WIND TUNNEL UNDER CONSTRUCTION. - NASA Langley Research Center, Full-Scale Wind Tunnel, 224 Hunting Avenue, Hampton, Hampton, VA

Full-Scale Field Test of Wake Steering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleming, Paul; Annoni, Jennifer; Scholbrock, Andrew

Wind farm control, in which turbine controllers are coordinated to improve farmwide performance, is an active field of research. One form of wind farm control is wake steering, in which a turbine is yawed to the inflow to redirect its wake away from downstream turbines. Wake steering has been studied in depth in simulations as well as in wind tunnels and scaled test facilities. This work performs a field test of wake steering on a full-scale turbine. In the campaign, the yaw controller of the turbine has been set to track different yaw misalignment set points while a nacelle-mounted lidarmore » scans the wake at several ranges downwind. The lidar measurements are combined with turbine data, as well as measurements of the inflow made by a highly instrumented meteorological mast. In conclusion, these measurements are then compared to the predictions of a wind farm control-oriented model of wakes.« less
Full-Scale Field Test of Wake Steering

DOE PAGES

Fleming, Paul; Annoni, Jennifer; Scholbrock, Andrew; ...

2017-06-13

Wind farm control, in which turbine controllers are coordinated to improve farmwide performance, is an active field of research. One form of wind farm control is wake steering, in which a turbine is yawed to the inflow to redirect its wake away from downstream turbines. Wake steering has been studied in depth in simulations as well as in wind tunnels and scaled test facilities. This work performs a field test of wake steering on a full-scale turbine. In the campaign, the yaw controller of the turbine has been set to track different yaw misalignment set points while a nacelle-mounted lidarmore » scans the wake at several ranges downwind. The lidar measurements are combined with turbine data, as well as measurements of the inflow made by a highly instrumented meteorological mast. In conclusion, these measurements are then compared to the predictions of a wind farm control-oriented model of wakes.« less
Flight Characteristics of a 1/4-Scale Model of the XFV-1 Airplane (TED No. NACA DE-378)

NASA Technical Reports Server (NTRS)

Kelly, Mark W.; Smaus, Louis H.

1952-01-01

A l/4-scale dynamically similar model of the XFV-1 airplane has been flown in the Ames 40- by 80-foot wind tunnel, using the trailing flight-cable technique. This investigation was devoted to establishing the flight characteristics of the model in forward flight from hovering to wing stall, and in yawed flight (wing span alined with the relative wind) from hovering to the maximum speed at which controlled flight could be maintained. Landings, take-offs, and hovering characteristics in flights close to the ground were also investigated.. Since the remote control system for the model was rather complicated and provided artificial damping about the pitch, roll, and yaw axes, sufficient data from the control-system calibration tests are included in this report to specify the performance of the control system in relation to both the model flight tests and the design of an automatic control system for the full-scale airplane. The model in hovering flight appeared to be neutrally stable. The response of the model to the controls was very rapid, and it was always necessary to provide some amount of artificial damping to maintain control. The model could be landed with little difficulty by hovering approximately a foot above the floor and then cutting the power. Take-offs were more difficult to perform, primarily because the rate of change in power to the model motors was limited by the characteristics of the available power source. The model was,capable of controlled yawed flight at translational velocities up to and including 20 feet per second. The effectiveness of the controls decreased with increasing speed, however, and at 25 fps control in pitch, and probably roll, was lost completely. The model was flown in controlled forward flight from hovering up to 70 fps. During these flights the model appeared to be more difficult to control in yaw than it was in pitch or roll. The flights of the model were recorded by motion picture cameras. These motion pictures are
Full-scale Wind-tunnel and Flight Tests of a Fairchild 22 Airplane Equipped with a Fowler Flap

NASA Technical Reports Server (NTRS)

Dearborn, C H; Soule, H A

1936-01-01

Full-scale wind-tunnel and flight tests were made of a Fairchild 22 airplane equipped with a Fowler flap to determine the effect of the flap on the performance and control characteristics of the airplane. In the wind-tunnel tests of the airplane with the horizontal tail surfaces removed, the flap was found to increase the maximum lift coefficient from 1.27 to 2.41. In the flight test, the flap was found to decrease the minimum speed from 58.8 to 44.4 miles per hour. The required take-off run to attain an altitude of 50 feet was reduced from 935 feet to 700 feet by the use of the flap, the minimum distance being obtained with five-sixths full deflection. The landing run from a height of 50 feet was reduced one-third. The longitudinal and directional control was adversely affected by the flap, indicating that the design of the tail surfaces is more critical with a flapped than a plain wing.
Acoustical characteristics of the NASA Langley full scale wind tunnel test section

NASA Technical Reports Server (NTRS)

Abrahamson, A. L.; Kasper, P. K.; Pappa, R. S.

1975-01-01

The full-scale wind tunnel at NASA-Langley Research Center was designed for low-speed aerodynamic testing of aircraft. Sound absorbing treatment has been added to the ceiling and walls of the tunnel test section to create a more anechoic condition for taking acoustical measurements during aerodynamic tests. The results of an experimental investigation of the present acoustical characteristics of the tunnel test section are presented. The experimental program included measurements of ambient nosie levels existing during various tunnel operating conditions, investigation of the sound field produced by an omnidirectional source, and determination of sound field decay rates for impulsive noise excitation. A comparison of the current results with previous measurements shows that the added sound treatment has improved the acoustical condition of the tunnel test section. An analysis of the data indicate that sound reflections from the tunnel ground-board platform could create difficulties in the interpretation of actual test results.
Large-Scale Boundary-Layer Control Tests on Two Wings in the NACA 20-Foot Wind Tunnel, Special Report

NASA Technical Reports Server (NTRS)

Freeman, Hugh B.

1935-01-01

Tests were made in the N.A.C.A. 20-foot wind tunnel on: (1) a wing, of 6.5-foot span, 5.5-foot chord, and 30 percent maximum thickness, fitted with large end plates and (2) a 16-foot span 2.67-foot chord wing of 15 percent maximum thickness to determine the increase in lift obtainable by removing the boundary layer and the power required for the blower. The results of the tests on the stub wing appeared more favorable than previous small-scale tests and indicated that: (1) the suction method was considerably superior to the pressure method, (2) single slots were more effective than multiple slots (where the same pressure was applied to all slots), the slot efficiency increased rapidly for increasing slot widths up to 2 percent of the wing chord and remained practically constant for all larger widths tested, (3) suction pressure and power requirements were quite low (a computation for a light airplane showed that a lift coefficient of 3.0 could be obtained with a suction as low as 2.3 times the dynamic pressure and a power expenditure less than 3 percent of the rated engine power), and (4) the volume of air required to be drawn off was quite high (approximately 0.5 cubic feet per second per unit wing area for an airplane landing at 40 miles per hour with a lift coefficient of 3,0), indicating that considerable duct area must be provided in order to prevent flow losses inside the wing and insure uniform distribution of suction along the span. The results from the tests of the large-span wing were less favorable than those on the stub wing. The reasons for this were, probably: (1) the uneven distribution of suction along the span, (2) the flow losses inside the wing, (3) the small radius of curvature of the leading edge of the wing section, and (4) the low Reynolds Number of these tests, which was about one half that of the stub wing. The results showed a large increase in the maximum lift coefficient with an increase in Reynolds Number in the range of the tests. The
Preliminary Performance Data on General Electric Integrated Electronic Control Operating on J47 RX1-3 Turbojet Engine in NACA Altitude Wind Tunnel

NASA Technical Reports Server (NTRS)

Blivas, Darnold; Taylor, Burt L., III

1950-01-01

Performance data obtained with recording oscillographs are presented to show the transient response of the General Electric Integrated Electronic Control operating on the J47 RXl-3 turbo-Jet engine over a range of altitudes from 10,000 to 45,000 feet and at ram pressure ratios of 1.03 and 1.4. These data represent the performance of the final control configuration developed after an investigation of the engine transient behavior in the NACA altitude wind tunnel. Oscillograph traces of controlled accelerations (throttle bursts),oontrolled decelerations (throttle chops), and controlled altitude starts are presented.
Seismic response of a full-scale wind turbine tower using experimental and numerical modal analysis

NASA Astrophysics Data System (ADS)

Kandil, Kamel Sayed Ahmad; Saudi, Ghada N.; Eltaly, Boshra Aboul-Anen; El-khier, Mostafa Mahmoud Abo

2016-12-01

Wind turbine technology has developed tremendously over the past years. In Egypt, the Zafarana wind farm is currently generating at a capacity of 517 MW, making it one of the largest onshore wind farms in the world. It is located in an active seismic zone along the west side of the Gulf of Suez. Accordingly, seismic risk assessment is demanded for studying the structural integrity of wind towers under expected seismic hazard events. In the context of ongoing joint Egypt-US research project "Seismic Risk Assessment of Wind Turbine Towers in Zafarana wind Farm Egypt" (Project ID: 4588), this paper describes the dynamic performance investigation of an existing Nordex N43 wind turbine tower. Both experimental and numerical work are illustrated explaining the methodology adopted to investigate the dynamic behavior of the tower under seismic load. Field dynamic testing of the full-scale tower was performed using ambient vibration techniques (AVT). Both frequency domain and time domain methods were utilized to identify the actual dynamic properties of the tower as built in the site. Mainly, the natural frequencies, their corresponding mode shapes and damping ratios of the tower were successfully identified using AVT. A vibration-based finite element model (FEM) was constructed using ANSYS V.12 software. The numerical and experimental results of modal analysis were both compared for matching purpose. Using different simulation considerations, the initial FEM was updated to finally match the experimental results with good agreement. Using the final updated FEM, the response of the tower under the AQABA earthquake excitation was investigated. Time history analysis was conducted to define the seismic response of the tower in terms of the structural stresses and displacements. This work is considered as one of the pioneer structural studies of the wind turbine towers in Egypt. Identification of the actual dynamic properties of the existing tower was successfully performed
Vertical-axis wind turbine experiments at full dynamic similarity

NASA Astrophysics Data System (ADS)

Duvvuri, Subrahmanyam; Miller, Mark; Brownstein, Ian; Dabiri, John; Hultmark, Marcus

2017-11-01

This study presents results from pressurized (upto 200 atm) wind tunnel tests of a self-spinning 5-blade model Vertical-Axis Wind Turbine (VAWT). The model is geometrically similar (scale ratio 1:22) to a commercially available VAWT, which has a rotor diameter of 2.17 meters and blade span of 3.66 meters, and is used at the Stanford university field lab. The use of pressurized air as working fluid allows for the unique ability to obtain full dynamic similarity with field conditions in terms of matched Reynolds numbers (Re), tip-speed ratios (λ), and Mach number (M). Tests were performed across a wide range of Re and λ, with the highest Re exceeding the maximum operational field Reynolds number (Remax) by a factor of 3. With an extended range of accessible Re conditions, the peak turbine power efficiency was seen to occur roughly at Re = 2 Remax and λ = 1 . Beyond Re > 2 Remax the turbine performance is invariant in Re for all λ. A clear demonstration of Reynolds number invariance for an actual full-scale wind turbine lends novelty to this study, and overall the results show the viability of the present experimental technique in testing turbines at field conditions.
Probabilistic Design of a Wind Tunnel Model to Match the Response of a Full-Scale Aircraft

NASA Technical Reports Server (NTRS)

Mason, Brian H.; Stroud, W. Jefferson; Krishnamurthy, T.; Spain, Charles V.; Naser, Ahmad S.

2005-01-01

design problem tractable. The results of the reliability-based designs performed in this paper show that large decreases in the probability of stress-based failure can be realized with only small sacrifices in the ability of the wind tunnel model to represent the displacements of the full-scale vehicle.
Altitude Wind Tunnel Drive Fan being Assembled

NASA Image and Video Library

1943-07-21

National Advisory Committee for Aeronautics (NACA) engineers assembled the Altitude Wind Tunnel’s (AWT) large wooden drive fan inside the hangar at the Aircraft Engine Research Laboratory. When it was built at the in the early 1940s the AWT was among the most complex test facilities ever designed. It was the first wind tunnel capable of operating full-scale engines under realistic flight conditions. This simulation included the reduction of air temperature, a decrease in air pressure, and the creation of an airstream velocity of up to 500 miles per hour. The AWT was constructed in 1942 and 1943. This photograph shows NACA engineers Lou Hermann and Jack Aust assembling the tunnel’s drive fan inside the hangar. The 12-bladed, 31-foot-diameter spruce wood fan would soon be installed inside the wind tunnel to create the high-speed airflow. This massive propeller was designed and constructed by the engine lab's design team at Langley Field. John Breisch, a Langley technician with several years of wind tunnel installation experience, arrived in Cleveland at the time of this photograph to supervise the fan assembly inside the hangar. He would return several weeks later to oversee the actual installation in the tunnel. The fan was driven at 410 revolutions per minute by an 18,000-horsepower General Electric induction motor that was located in the rear corner of the Exhauster Building. An extension shaft connected the motor to the fan. A bronze screen protected the fan against damage from failed engine parts sailing through the tunnel. Despite this screen the blades did become worn or cracked over time and had to be replaced. An entire new fan was installed in 1951.
Complete NACA Muroc Staff of 1954, in front of new NACA building (4800)

NASA Technical Reports Server (NTRS)

1954-01-01

The employees of the NACA High-Speed Flight Station are gathered for a 1954 photo shoot on the front steps of building 4800, the new NACA Facility at Main Base of Edwards Air Force Base, California. This new building was considerably larger than the earlier NACA buildings on South Base, but then the staff had increased and the extra space was needed. From 1950 when an earlier group picture was taken (E-33717) until 1954 the staff at NACA increased from 132 to 250. As the workload increased and more research flights were completed the complement of employees grew to 662 in 1966. More changes took place in 1954 with the Station being called the NACA High-Speed Flight Station. A further name change occurred in October 1958 to the National Aeronautics and Space Administration (NASA) High-Speed Flight Station and again in September 1959 to the NASA Flight Research Center. There would be two more name changes before the next group photo (EC85-33160-2) would be made. On March 1976 to NASA Hugh L. Dryden Flight Research Center and in October 1981 when the Center became the Ames-Dryden Flight Research Facility.
Tests of Round and Flat Spoilers on a Tapered Wing in the NACA 19-Foot Pressure Wind Tunnel

NASA Technical Reports Server (NTRS)

Wenzinger, Carl J; Bowen, John D

1941-01-01

Several arrangements of round and flat spanwise spoilers attached to the upper surface of a tapered wing were tested in the NACA 19-foot pressure wind tunnel to determine the most effective type, location, and size of spoiler necessary to reduce greatly the lift on the wings of large flying boats when moored. The effect of the various spoilers on the lift, the drag, and the pitching-moment characteristics of the tapered wing was measured over a range of angles of attack from zero to maximum lift. The most effective type of spoiler was found to be the flat type with no space between it and the wing surface. The chordwise location of such a spoiler was not critical within the range investigated, from 5 to 20 percent of the wing chord from the leading edge.
Darrieus wind-turbine airfoil configurations

NASA Astrophysics Data System (ADS)

Migliore, P. G.; Fritschen, J. R.

1982-06-01

The purpose was to determine what aerodynamic performance improvement, if any, could be achieved by judiciously choosing the airfoil sections for Darrieus wind turbine blades. Ten different airfoils, having thickness to chord ratios of twelve, fifteen and eighteen percent, were investigated. Performance calculations indicated that the NACA 6-series airfoils yield peak power coefficients at least as great as the NACA. Furthermore, the power coefficient-tip speed ratio curves were broader and flatter for the 6-series airfoils. Sample calculations for an NACA 63 sub 2-015 airfoil showed an annual energy output increase of 17 to 27% depending upon rotor solidity, compared to an NACA 0015 airfoil. An attempt was made to account for the flow curvature effects associated with Darrieus turbines by transforming the NACA 63 sub 2-015 airfoil to an appropriate shape.
B-29 Superfortress Engine in the Altitude Wind Tunnel

NASA Image and Video Library

1944-07-21

The resolution of the Boeing B-29 Superfortress’ engine cooling problems was one of the Aircraft Engine Research Laboratory’s (AERL) key contributions to the World War II effort. The B-29 leapfrogged previous bombers in size, speed, and altitude capabilities. The B–29 was intended to soar above anti-aircraft fire and make pinpoint bomb drops onto strategic targets. Four Wright Aeronautical R-3350 engines powered the massive aircraft. The engines, however, frequently strained and overheated due to payload overloading. This resulted in a growing number of engine fires that often resulted in crashes. The military asked the NACA to tackle the overheating issue. Full-scale engine tests on a R–3350 engine in the Prop House demonstrated that a NACA-designed impeller increased the fuel injection system’s flow rate. Single-cylinder studies resolved a valve failure problem by a slight extension of the cylinder head, and researchers in the Engine Research Building combated uneven heating with a new fuel injection system. Investigations during the summer of 1944 in the Altitude Wind Tunnel, which could simulate flight conditions at high altitudes, led to reduction of drag and improved air flow by reshaping the cowling inlet and outlet. The NACA modifications were then flight tested on a B-29 bomber that was brought to the AERL.
A laser-sheet flow visualization technique for the large wind tunnels of the National Full-Scale Aerodynamics Complex

NASA Technical Reports Server (NTRS)

Reinath, M. S.; Ross, J. C.

1990-01-01

A flow visualization technique for the large wind tunnels of the National Full Scale Aerodynamics Complex (NFAC) is described. The technique uses a laser sheet generated by the NFAC Long Range Laser Velocimeter (LRLV) to illuminate a smoke-like tracer in the flow. The LRLV optical system is modified slightly, and a scanned mirror is added to generate the sheet. These modifications are described, in addition to the results of an initial performance test conducted in the 80- by 120-Foot Wind Tunnel. During this test, flow visualization was performed in the wake region behind a truck as part of a vehicle drag reduction study. The problems encountered during the test are discussed, in addition to the recommended improvements needed to enhance the performance of the technique for future applications.
Optimization of Wind Turbine Airfoils/Blades and Wind Farm Layouts

NASA Astrophysics Data System (ADS)

Chen, Xiaomin

Shape optimization is widely used in the design of wind turbine blades. In this dissertation, a numerical optimization method called Genetic Algorithm (GA) is applied to address the shape optimization of wind turbine airfoils and blades. In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. The FX, DU and NACA 64 series airfoils are thick airfoils widely used for wind turbine blade application. They have several advantages in meeting the intrinsic requirements for wind turbines in terms of design point, off-design capabilities and structural properties. This research employ both single- and multi-objective genetic algorithms (SOGA and MOGA) for shape optimization of Flatback, FX, DU and NACA 64 series airfoils to achieve maximum lift and/or maximum lift to drag ratio. The commercially available software FLUENT is employed for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a two-equation Shear Stress Transport (SST) turbulence model and a three equation k-kl-o turbulence model. The optimization methodology is validated by an optimization study of subsonic and transonic airfoils (NACA0012 and RAE 2822 airfoils). In this dissertation, we employ DU 91-W2-250, FX 66-S196-V1, NACA 64421, and Flat-back series of airfoils (FB-3500-0050, FB-3500-0875, and FB-3500-1750) and compare their performance with S809 airfoil used in NREL Phase II and III wind turbines; the lift and drag coefficient data for these airfoils sections are available. The output power of the turbine is calculated using these airfoil section blades for a given B and lambda and is compared with the original NREL Phase II and Phase III turbines using S809 airfoil section. It is shown that by a suitable choice of airfoil section of HAWT blade, the power generated
Interference of Wing and Fuselage from Tests of 209 Combinations in the NACA Variable-Density Tunnel

NASA Technical Reports Server (NTRS)

Jacobs, Eastman N; Ward, Kenneth E

1936-01-01

This report presents the results of tests of 209 simple wing-fuselage combinations made in the NACA variable-density wind tunnel to provide information regarding the effects of aerodynamic interference between wings and fuselages at a large value of Reynolds number.
NASA Agricultural Aircraft Research Program in the Langley Vortex Research Facility and the Langley Full Scale Wind Tunnel

NASA Technical Reports Server (NTRS)

Jordan, F. L., Jr.; Mclemore, H. C.; Bragg, M. B.

1978-01-01

The current status of aerial applications technology research at the Langley's Vortex Research Facility and Full-Scale Wind Tunnel is reviewed. Efforts have been directed mainly toward developing and validating the required experimental and theoretical research tools. A capability to simulate aerial dispersal of materials from agricultural airplanes with small-scale airplane models, numerical methods, and dynamically scaled test particles was demonstrated. Tests on wake modification concepts have proved the feasibility of tailoring wake properties aerodynamically to produce favorable changes in deposition and to provide drift control. An aerodynamic evaluation of the Thrush Commander 800 agricultural airplane with various dispersal systems installed is described. A number of modifications intended to provide system improvement to both airplane and dispersal system are examined, and a technique for documenting near-field spray characteristics is evaluated.
Review Report on Design Study and Economic Assessment of Multi-Unit Offshore Wind Energy Conversion Systems Applications,

DTIC Science & Technology

1977-03-21

meter turbine . Available from NTIS; $6.50. 113 pages. 7. SAND-76-0130 Wind Tunnel Performance Data for the Darrieus Wind Tur- bine with NACA-0012...2-meter-diameter Darrieus wind turbine have been tested in a low speed wind tunnel. The airfoil section for all configurations was NACA 0012. The... Darrieus Vertical-Axis Wind Turbine Program at Sandia Laboratories, Kadlec, E.G., published by Sandia Laboratories 1976. Contract No. AT(29-1)-789. From

Coordinating Council. Fourth Meeting: NACA Documents Database Project

NASA Technical Reports Server (NTRS)

1991-01-01

This NASA Scientific and Technical Information Coordination Council meeting dealt with the topic 'NACA Documents Database Project'. The following presentations were made and reported on: NACA documents database project study plan, AIAA study, the Optimal NACA database, Deficiencies in online file, NACA documents: Availability and Preservation, the NARA Collection: What is in it? and What to do about it?, and NACA foreign documents and availability. Visuals are available for most presentations.
Design analysis of vertical wind turbine with airfoil variation

NASA Astrophysics Data System (ADS)

Maulana, Muhammad Ilham; Qaedy, T. Masykur Al; Nawawi, Muhammad

2016-03-01

With an ever increasing electrical energy crisis occurring in the Banda Aceh City, it will be important to investigate alternative methods of generating power in ways different than fossil fuels. In fact, one of the biggest sources of energy in Aceh is wind energy. It can be harnessed not only by big corporations but also by individuals using Vertical Axis Wind Turbines (VAWT). This paper presents a three-dimensional CFD analysis of the influence of airfoil design on performance of a Darrieus-type vertical-axis wind turbine (VAWT). The main objective of this paper is to develop an airfoil design for NACA 63-series vertical axis wind turbine, for average wind velocity 2,5 m/s. To utilize both lift and drag force, some of designs of airfoil are analyzed using a commercial computational fluid dynamics solver such us Fluent. Simulation is performed for this airfoil at different angles of attach rearranging from -12°, -8°, -4°, 0°, 4°, 8°, and 12°. The analysis showed that the significant enhancement in value of lift coefficient for airfoil NACA 63-series is occurred for NACA 63-412.
Wind Tunnel Visualization of the Flow Over a Full-Scale F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lanser, Wendy R.; Botha, Gavin J.; James, Kevin D.; Crowder, James P.; Schmitz, Fredric H. (Technical Monitor)

1994-01-01

The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. This investigation used both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, leading edge extensions (LEXs), and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system. The flow visualization experiments were conducted over an angle of attack range from 20deg to 45deg and over a sideslip range from -10deg to 10deg. The results show regions of attached and separated flow on the forebody, canopy, and wings. Additionally, the vortical flow is clearly visible over the leading-edge extensions, canopy, and wings.
Wind-tunnel investigation of effect of interference on lateral-stability characteristics of four NACA 23012 wings, an elliptical and a circular fuselage and vertical fins

NASA Technical Reports Server (NTRS)

House, Rufus O; Wallace, Arthur R

1941-01-01

Report presents the results of a wind-tunnel investigation of the effect of wing-fuselage interference on lateral-stability characteristics made in the NACA 7 by 10-foot wind tunnel on four fuselages and two fins, representing high-wing, low-wing, and midwing monoplanes. The fuselages are of circular and elliptical cross section. The wings have rounded tips and, in plan form, one is rectangular and the three are tapered 3:1 with various amounts of sweep. The rate of change in the coefficients of rolling moment, yawing moment, and lateral force with angle of yaw is given in a form to show the increment caused by wing-fuselage interference for the model with no fin and the effect of wing-fuselage interference on fin effectiveness. Results for the fuselage-fin combination and the wing tested alone are also given.
Buffeting of NACA 0012 airfoil at high angle of attack

NASA Astrophysics Data System (ADS)

Zhou, Tong; Dowell, Earl

2014-11-01

Buffeting is a fluid instability caused by flow separation or shock wave oscillations in the flow around a bluff body. Typically there is a dominant frequency of these flow oscillations called Strouhal or buffeting frequency. In prior work several researchers at Duke University have noted the analogy between the classic Von Karman Vortex Street behind a bluff body and the flow oscillations that occur for flow around a NACA 0012 airfoil at sufficiently large angle of attack. Lock-in is found for certain combinations of airfoil oscillation (pitching motion) frequencies and amplitudes when the frequency of the airfoil motion is sufficiently close to the buffeting frequency. The goal of this paper is to explore the flow around a static and an oscillating airfoil at high angle of attack by developing a method for computing buffet response. Simulation results are compared with experimental data. Conditions for the onset of buffeting and lock-in of a NACA 0012 airfoil at high angle of attack are determined. Effects of several parameters on lift coefficient and flow response frequency are studied including Reynolds number, angle of attack and blockage ratio of the airfoil size to the wind tunnel dimensions. Also more detailed flow field characteristics are determined. For a static airfoil, a universal Strouhal number scaling has been found for angles of attack from 30° to 90°, where the flow around airfoil is fully separated. For an oscillating airfoil, conditions for lock-in are discussed. Differences between the lock-in case and the unlocked case are also studied. The second affiliation: Duke University.
Roughness sensitivity comparisons of wind turbine blade sections

NASA Astrophysics Data System (ADS)

Wilcox, Benjamin Jacob

One explanation for wind turbine power degradation is insect roughness. Historical studies on insect-induced power degradation have used simulation methods which are either unrepresentative of actual insect roughness or too costly or time-consuming to be applied to wide-scale testing. Furthermore, the role of airfoil geometry in determining the relations between insect impingement locations and roughness sensitivity has not been studied. To link the effects of airfoil geometry, insect impingement locations, and roughness sensitivity, a simulation code was written to determine representative insect collection patterns for different airfoil shapes. Insect collection pattern data was then used to simulate roughness on an NREL S814 airfoil that was tested in a wind tunnel at Reynolds numbers between 1:6 x 106 and 4:0 x 106. Results are compared to previous tests of a NACA 633-418 airfoil. Increasing roughness height and density results in decreased maximum lift, lift curve slope, and lift-to-drag ratio. Increasing roughness height, density, or Reynolds number results in earlier bypass transition, with critical roughness Reynolds numbers lying within the historical range. Increased roughness sensitivity on the 25% thick NREL S814 is observed compared to the 18% thick NACA 633-418. Blade-element-momentum analysis was used to calculate annual energy production losses of 4.9% and 6.8% for a NACA 633-418 turbine and an NREL S814 turbine, respectively, operating with 200 microm roughness. These compare well to historical field measurements.
Assessment of Scaled Rotors for Wind Tunnel Experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maniaci, David Charles; Kelley, Christopher Lee; Chiu, Phillip

2015-07-01

Rotor design and analysis work has been performed to support the conceptualization of a wind tunnel test focused on studying wake dynamics. This wind tunnel test would serve as part of a larger model validation campaign that is part of the Department of Energy Wind and Water Power Program’s Atmosphere to electrons (A2e) initiative. The first phase of this effort was directed towards designing a functionally scaled rotor based on the same design process and target full-scale turbine used for new rotors for the DOE/SNL SWiFT site. The second phase focused on assessing the capabilities of an already available rotor,more » the G1, designed and built by researchers at the Technical University of München.« less
Full-scale hingeless rotor performance and loads

NASA Technical Reports Server (NTRS)

Peterson, Randall L.

1995-01-01

A full-scale BO-105 hingeless rotor system was tested in the NASA Ames 40- by 80-Foot Wind Tunnel on the rotor test apparatus. Rotor performance, rotor loads, and aeroelastic stability as functions of both collective and cyclic pitch, tunnel velocity, and shaft angle were investigated. This test was performed in support of the Rotor Data Correlation Task under the U.S. Army/German Memorandum of Understanding on Cooperative Research in the Field of Helicopter Aeromechanics. The primary objective of this test program was to create a data base for full-scale hingeless rotor performance and structural blade loads. A secondary objective was to investigate the ability to match flight test conditions in the wind tunnel. This data base can be used for the experimental and analytical studies of hingeless rotor systems over large variations in rotor thrust and tunnel velocity. Rotor performance and structural loads for tunnel velocities from hover to 170 knots and thrust coefficients (C(sub T)/sigma) from 0.0 to 0.12 are presented in this report. Thrust sweeps at tunnel velocities of 10, 20, and 30 knots are also included in this data set.
FUN3D Airload Predictions for the Full-Scale UH-60A Airloads Rotor in a Wind Tunnel

NASA Technical Reports Server (NTRS)

Lee-Rausch, Elizabeth M.; Biedron, Robert T.

2013-01-01

An unsteady Reynolds-Averaged Navier-Stokes solver for unstructured grids, FUN3D, is used to compute the rotor performance and airloads of the UH-60A Airloads Rotor in the National Full-Scale Aerodynamic Complex (NFAC) 40- by 80-foot Wind Tunnel. The flow solver is loosely coupled to a rotorcraft comprehensive code, CAMRAD-II, to account for trim and aeroelastic deflections. Computations are made for the 1-g level flight speed-sweep test conditions with the airloads rotor installed on the NFAC Large Rotor Test Apparatus (LRTA) and in the 40- by 80-ft wind tunnel to determine the influence of the test stand and wind-tunnel walls on the rotor performance and airloads. Detailed comparisons are made between the results of the CFD/CSD simulations and the wind tunnel measurements. The computed trends in solidity-weighted propulsive force and power coefficient match the experimental trends over the range of advance ratios and are comparable to previously published results. Rotor performance and sectional airloads show little sensitivity to the modeling of the wind-tunnel walls, which indicates that the rotor shaft-angle correction adequately compensates for the wall influence up to an advance ratio of 0.37. Sensitivity of the rotor performance and sectional airloads to the modeling of the rotor with the LRTA body/hub increases with advance ratio. The inclusion of the LRTA in the simulation slightly improves the comparison of rotor propulsive force between the computation and wind tunnel data but does not resolve the difference in the rotor power predictions at mu = 0.37. Despite a more precise knowledge of the rotor trim loads and flight condition, the level of comparison between the computed and measured sectional airloads/pressures at an advance ratio of 0.37 is comparable to the results previously published for the high-speed flight test condition.
Noise Suppression Addition to the 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1950-08-21

The 8- by 6-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory was the largest supersonic wind tunnel in the nation at the time and the only one able to test full-scale engines at supersonic speeds. The 8- by 6 was designed as a non-return and open-throat tunnel. A large compressor created the air flow at one end of the tunnel, squeezed the flow to increase its velocity just before the test section, then reduced the velocity, and expelled it into the atmosphere at the other end of the tunnel. This design worked well for initial aerodynamic testing, but the local community was literally rattled by the noise and vibrations when researchers began running engines in the test section in January 1950. The NACA’s most modern wind tunnel was referred to as “an 87,000-horsepower bugle aimed at the heart of Cleveland.” NACA Lewis responded to the complaints by adding an acoustic housing at the end of the tunnel to dampen the noise. The structure included resonator chambers and a reinforced concrete muffler structure. Modifications continued over the years. A return leg was added, and a second test section, 9 -by 15-foot, was incorporated in the return leg in the 1960s. Since its initial operation in 1948, the 8- by 6-foot tunnel has been aggressively used to support the nation's aeronautics and space programs for the military, industry, and academia.
Comparison of theoretically predicted lateral-directional aerodynamic characteristics with full-scale wind tunnel data on the ATLIT airplane

NASA Technical Reports Server (NTRS)

Griswold, M.; Roskam, J.

1980-01-01

An analytical method is presented for predicting lateral-directional aerodynamic characteristics of light twin engine propeller-driven airplanes. This method is applied to the Advanced Technology Light Twin Engine airplane. The calculated characteristics are correlated against full-scale wind tunnel data. The method predicts the sideslip derivatives fairly well, although angle of attack variations are not well predicted. Spoiler performance was predicted somewhat high but was still reasonable. The rudder derivatives were not well predicted, in particular the effect of angle of attack. The predicted dynamic derivatives could not be correlated due to lack of experimental data.
NACA Researcher Examines the Cyclotron

NASA Image and Video Library

1951-02-21

Researcher James Blue examines the new cyclotron at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. Researchers at NACA Lewis began postulating about the use of atomic power for propulsion immediately after World War II. The NACA concentrated its efforts on the study of high temperature materials and heat transfer since it did not have access to the top secret fission information. The military studied the plausibility of nuclear propulsion for aircraft in the late 1940s. The military program was cancelled after four years without any breakthroughs, but the Atomic Energy Commission took on the effort in 1951. The NACA Lewis laboratory was expanding its nuclear-related research during this period. In 1948, Lewis engineers were assigned to the Oak Ridge National Laboratory to obtain expertise in high temperature heat transfer and advanced materials technology. The following year a new 80-person Nuclear Reactor Division was created, and an in-house nuclear school was established to train these researchers. The cyclotron was built behind the Materials and Structures Laboratory to support thermodynamic and materials research for both nuclear aircraft and nuclear rockets. The original NACA Lewis cyclotron was used to accelerate two kinds of particles. To better match the space radiation environment, the cyclotron was later modified to accelerate particles of the newly-discovered Van Allen radiation belts.
Altitude Wind Tunnel Operating at Night

NASA Image and Video Library

1945-04-21

The Altitude Wind Tunnel (AWT) during one of its overnight runs at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory in Cleveland, Ohio. The AWT was run during night hours so that its massive power loads were handled when regional electric demands were lowest. At the time the AWT was among the most complex wind tunnels ever designed. In order to simulate conditions at high altitudes, NACA engineers designed innovative new systems that required tremendous amounts of electricity. The NACA had an agreement with the local electric company that it would run its larger facilities overnight when local demand was at its lowest. In return the utility discounted its rates for the NACA during those hours. The AWT could produce wind speeds up to 500 miles per hour through its 20-foot-diameter test section at the standard operating altitude of 30,000 feet. The airflow was created by a large fan that was driven by an 18,000-horsepower General Electric induction motor. The altitude simulation was accomplished by large exhauster and refrigeration systems. The cold temperatures were created by 14 Carrier compressors and the thin atmosphere by four 1750-horsepower exhausters. The first and second shifts usually set up and broke down the test articles, while the third shift ran the actual tests. Engineers would often have to work all day, then operate the tunnel overnight, and analyze the data the next day. The night crew usually briefed the dayshift on the tests during morning staff meetings.
Abe Silverstein Leads Tour of the 10- by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1955-11-21

Abe Silverstein, Associate Director of the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory, provides a personal tour of the new 10- by 10-Foot Supersonic Wind Tunnel for US Senator George Bender (hat in hand) and General Lemuel Shepherd. Shepherd was Commandant of the Marine Corps and had served in World War I, World War II, and the Korean War. The general was accompanied by Admiral Herbert Leary, in dark uniform. Bender was a Republican Senator from Ohio. Behind Bender is President of the Cleveland Chamber of Commerce Curtis Smith. NACA Lewis managers Eugene Manganiello and Wilson Hunter assist with the tour. Abe Silverstein oversaw all research at the laboratory. Upon taking his post in 1952 he reorganized the research staff and began shifting the focus away from airbreathing aircraft engines to new fields such as high energy fuels, electric propulsion, and nuclear power and propulsion. He was an early advocate of the NACA’s involvement in the space program and crucial to the founding of National Aeronautics and Space Administration in 1958. Silverstein began his career helping design and conduct research in the Full Scale Tunnel in 1929 at the Langley Memorial Aeronautical Laboratory. Silverstein advocated a series of increasingly large supersonic wind tunnels after the war, culminating in the 10- by 10.
Non-Axisymmetric Line Driven Disc Winds II - Full Velocity Gradient

NASA Astrophysics Data System (ADS)

Dyda, Sergei; Proga, Daniel

2018-05-01

We study non-axisymetric features of 3D line driven winds in the Sobolev approximation, where the optical depth is calculated using the full velocity gradient. We find that non-axisymmetric density features, so called clumps, form primarily at the base of the wind on super-Sobolev length scales. The density of clumps differs by a factor of ˜3 from the azimuthal average, the magnitude of their velocity dispersion is comparable to the flow velocity and they produce ˜20% variations in the column density. Clumps may be observable because differences in density produce enhancements in emission and absorption profiles or through their velocity dispersion which enhances line broadening.
Force Tests of the Boeing XB-47 Full-Scale Empennage in the Ames 40- by 80-Foot Wind Tunnel

NASA Technical Reports Server (NTRS)

Hunton, Lynn W.

1947-01-01

A wind-tunnel investigation of the Boeing XB-47 full-scale empennage was conducted to provide, prior to flight tests, data required on the effectiveness of the elevator and rudder. The XB-47 airplane is a jet-propelled medium bomber having wing and tail surfaces swept back 35 degrees. The investigation included tests of the effectiveness of the elevator with normal straight sides, with a buldged trailing edge, and with a modified hinge-line gap and tests of the effectiveness of the rudder with a normal straight-sided tab and with a bulged tab.
Numerical evaluation of the scale problem on the wind flow of a windbreak

PubMed Central

Liu, Benli; Qu, Jianjun; Zhang, Weimin; Tan, Lihai; Gao, Yanhong

2014-01-01

The airflow field around wind fences with different porosities, which are important in determining the efficiency of fences as a windbreak, is typically studied via scaled wind tunnel experiments and numerical simulations. However, the scale problem in wind tunnels or numerical models is rarely researched. In this study, we perform a numerical comparison between a scaled wind-fence experimental model and an actual-sized fence via computational fluid dynamics simulations. The results show that although the general field pattern can be captured in a reduced-scale wind tunnel or numerical model, several flow characteristics near obstacles are not proportional to the size of the model and thus cannot be extrapolated directly. For example, the small vortex behind a low-porosity fence with a scale of 1:50 is approximately 4 times larger than that behind a full-scale fence. PMID:25311174
Electrogenic Na+/Ca2+ Exchange

PubMed Central

Danaceau, Jonathan P.; Lucero, Mary T.

2000-01-01

Olfactory receptor neurons (ORNs) from the squid, Lolliguncula brevis, respond to the odors l-glutamate or dopamine with increases in internal Ca2+ concentrations ([Ca2+]i). To directly asses the effects of increasing [Ca2+]i in perforated-patched squid ORNs, we applied 10 mM caffeine to release Ca2+ from internal stores. We observed an inward current response to caffeine. Monovalent cation replacement of Na+ from the external bath solution completely and selectively inhibited the caffeine-induced response, and ruled out the possibility of a Ca2+-dependent nonselective cation current. The strict dependence on internal Ca2+ and external Na+ indicated that the inward current was due to an electrogenic Na+/Ca2+ exchanger. Block of the caffeine-induced current by an inhibitor of Na+/Ca2+ exchange (50–100 μM 2′,4′-dichlorobenzamil) and reversibility of the exchanger current, further confirmed its presence. We tested whether Na+/Ca2+ exchange contributed to odor responses by applying the aquatic odor l-glutamate in the presence and absence of 2′,4′-dichlorobenzamil. We found that electrogenic Na+/Ca2+ exchange was responsible for ∼26% of the total current associated with glutamate-induced odor responses. Although Na+/Ca2+ exchangers are known to be present in ORNs from numerous species, this is the first work to demonstrate amplifying contributions of the exchanger current to odor transduction. PMID:10828249
Construction of the 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1948-06-21

The 8- by 6-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory was the nation’s largest supersonic facility when it began operation in April 1949. The emergence of new propulsion technologies such as turbojets, ramjets, and rockets during World War II forced the NACA and the aircraft industry to develop new research tools. In late 1945 the NACA began design work for new large supersonic wind tunnels at its three laboratories. The result was the 4- by 4-Foot Supersonic Wind Tunnel at Langley Memorial Aeronautical Laboratory, 6- by 6-foot supersonic wind tunnel at Ames Aeronautical Laboratory, and the largest facility, the 8- by 6-Foot Supersonic Wind Tunnel in Cleveland. The two former tunnels were to study aerodynamics, while the 8- by 6 facility was designed for supersonic propulsion. The 8- by 6-Foot Supersonic Wind Tunnel was used to study propulsion systems, including inlets and exit nozzles, combustion fuel injectors, flame holders, exit nozzles, and controls on ramjet and turbojet engines. Flexible sidewalls alter the tunnel’s nozzle shape to vary the Mach number during operation. A seven-stage axial compressor, driven by three electric motors that yield a total of 87,000 horsepower, generates air speeds from Mach 0.36 to 2.0. A section of the tunnel is seen being erected in this photograph.
Sub-scale Inverse Wind Turbine Blade Design Using Bound Circulation

NASA Astrophysics Data System (ADS)

Kelley, Christopher; Berg, Jonathan

2014-11-01

A goal of the National Rotor Testbed project at Sandia is to design a sub-scale wind turbine blade that has similitude to a modern, commercial size blade. However, a smaller diameter wind turbine operating at the same tip-speed-ratio exhibits a different range of operating Reynolds numbers across the blade span, thus changing the local lift and drag coefficients. Differences to load distribution also affect the wake dynamics and stability. An inverse wind turbine blade design tool has been implemented which uses a target, dimensionless circulation distribution from a full-scale blade to find the chord and twist along a sub-scale blade. In addition, airfoil polar data are interpolated from a few specified span stations leading to a smooth, manufacturable blade. The iterative process perturbs chord and twist, after running a blade element momentum theory code, to reduce the residual sum of the squares between the modeled sub-scale circulation and the target full-scale circulation. It is shown that the converged sub-scale design also leads to performance similarity in thrust and power coefficients. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy under Contract DE-AC04-94AL85000.

Spatial correlation of atmospheric wind at scales relevant for large scale wind turbines

NASA Astrophysics Data System (ADS)

Bardal, L. M.; Sætran, L. R.

2016-09-01

Wind measurements a short distance upstream of a wind turbine can provide input for a feedforward wind turbine controller. Since the turbulent wind field will be different at the point/plane of measurement and the rotor plane the degree of correlation between wind speed at two points in space both in the longitudinal and lateral direction should be evaluated. This study uses a 2D array of mast mounted anemometers to evaluate cross-correlation of longitudinal wind speed. The degree of correlation is found to increase with height and decrease with atmospheric stability. The correlation is furthermore considerably larger for longitudinal separation than for lateral separation. The integral length scale of turbulence is also considered.
Roughness Sensitivity Comparisons of Wind Turbine Blade Sections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilcox, Benjamin J.; White, Edward B.; Maniaci, David Charles

One explanation for wind turbine power degradation is insect roughness. Historical studies on insect-induced power degradation have used simulation methods which are either un- representative of actual insect roughness or too costly or time-consuming to be applied to wide-scale testing. Furthermore, the role of airfoil geometry in determining the relations between insect impingement locations and roughness sensitivity has not been studied. To link the effects of airfoil geometry, insect impingement locations, and roughness sensitivity, a simulation code was written to determine representative insect collection patterns for different airfoil shapes. Insect collection pattern data was then used to simulate roughness onmore » an NREL S814 airfoil that was tested in a wind tunnel at Reynolds numbers between 1.6 x 10 6 and 4.0 x 10 6. Results are compared to previous tests of a NACA 63 3 -418 airfoil. Increasing roughness height and density results in decreased maximum lift, lift curve slope, and lift-to-drag ratio. Increasing roughness height, density, or Reynolds number results in earlier bypass transition, with critical roughness Reynolds numbers lying within the historical range. Increased roughness sensitivity on the 25% thick NREL S814 is observed compared to the 18% thick NACA 63 3 -418. Blade-element-momentum analysis was used to calculate annual energy production losses of 4.9% and 6.8% for a NACA 63 3 -418 turbine and an NREL S814 turbine, respectively, operating with 200 μm roughness. These compare well to historical field measurements.« less
Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

USGS Publications Warehouse

Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

2000-01-01

Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As
Wake characteristics of wind turbines in utility-scale wind farms

NASA Astrophysics Data System (ADS)

Yang, Xiaolei; Foti, Daniel; Sotiropoulos, Fotis

2017-11-01

The dynamics of turbine wakes is affected by turbine operating conditions, ambient atmospheric turbulent flows, and wakes from upwind turbines. Investigations of the wake from a single turbine have been extensively carried out in the literature. Studies on the wake dynamics in utility-scale wind farms are relatively limited. In this work, we employ large-eddy simulation with an actuator surface or actuator line model for turbine blades to investigate the wake dynamics in utility-scale wind farms. Simulations of three wind farms, i.e., the Horns Rev wind farm in Denmark, Pleasant Valley wind farm in Minnesota, and the Vantage wind farm in Washington are carried out. The computed power shows a good agreement with measurements. Analysis of the wake dynamics in the three wind farms is underway and will be presented in the conference. This work was support by Xcel Energy (RD4-13). The computational resources were provided by National Renewable Energy Laboratory.
Boeing B-47 Bomber with an Ejector at the 1957 NACA Lewis Inspection

NASA Image and Video Library

1957-10-21

A Boeing B-47 Stratojet bomber with a noise-reducing ejector on its engine at the 1957 Inspection of the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. Representatives from the military, aeronautical industry, universities, and the press were invited to the laboratory to be briefed on the NACA’s latest research efforts and tour the state- of- the- art test facilities. Over 1700 people visited the NACA Lewis in Cleveland, Ohio during October 7 - 10, 1957. By the mid-1950s, the aircraft industry was close to introducing jet airliners to the nation’s airways. The noise produced by the large jet engines, however, would pose a considerable problem for communities near airports. This problem was demonstrated at the 1957 Inspection by an NACA Lewis researcher who played longplay (LP) audio records of military jet engines for an audience. Tests showed that the source of the loudest noise was not the engine itself, but the mixing of the engine’s exhaust with the surrounding air in the atmosphere. The pressures resulting from this turbulence produced sound waves. One of Lewis’ first studies sought to design an exhaust nozzle that reduced the turbulence. A Pratt and Whitney J57 was tested in the Altitude Wind Tunnel with many of these nozzle configurations from January to May 1957. Researchers found that the various nozzle types did reduce the noise levels but also reduced the aircraft’s thrust. Afterwards, they determined that the addition of an NACA-developed ejector reduced the noise levels without diminishing thrust.
Numerical investigation of flow on NACA4412 aerofoil with different aspect ratios

NASA Astrophysics Data System (ADS)

Demir, Hacımurat; Özden, Mustafa; Genç, Mustafa Serdar; Çağdaş, Mücahit

2016-03-01

In this study, the flow over NACA4412 was investigated both numerically and experimentally at a different Reynolds numbers. The experiments were carried out in a low speed wind tunnel with various angles of attack and different Reynolds numbers (25000 and 50000). Airfoil was manufactured using 3D printer with a various aspect ratios (AR = 1 and AR = 3). Smoke-wire and oil flow visualization methods were used to visualize the surface flow patterns. NACA4412 aerofoil was designed by using SOLIDWORKS. The structural grid of numerical model was constructed by ANSYS ICEM CFD meshing software. Furthermore, ANSYS FLUENT™ software was used to perform numerical calculations. The numerical results were compared with experimental results. Bubble formation was shown in CFD streamlines and smoke-wire experiments at z / c = 0.4. Furthermore, bubble shrunk at z / c = 0.2 by reason of the effects of tip vortices in both numerical and experimental studies. Consequently, it was seen that there was a good agreement between numerical and experimental results.
Take-Off and Landing Characteristics of a 0.13-Scale Model of the Convair XFY-1 Vertically Rising Airplane in Steady Winds, TED No. NACA DE 368

NASA Technical Reports Server (NTRS)

Schade, Robert O.; Smith, Charles C., Jr.; Lovell, P. M., Jr.

1954-01-01

An experimental investigation has been conducted to determine the stability and control characteristics of a 0.13-scale free-flight model of the Convair XFY-1 airplane during take-offs and landings in steady winds. The tests indicated that take-offs in headwinds up to at least 20 knots (full scale) will be fairly easy to perform although the airplane may be blown downstream as much as 3 spans before a trim condition can be established. The distance that the airplane will be blown down-stream can be reduced by restraining the upwind landing gear until the instant of take-off. The tests also indicated that spot landings in headwinds up to at least 30 knots (full scale) and in crosswinds up to at least 20 knots (full scale) can be accomplished with reasonable accuracy although, during the landing approach, there will probably be an undesirable nosing-up tendency caused by ground effect and by the change in angle of attack resulting from vertical descent. Some form of arresting gear will probably be required to prevent the airplane from rolling downwind or tipping over after contact. This rolling and tipping can be prevented by a snubbing line attached to the tip of the upwind' wing or tail or by an arresting gear consisting of a wire mesh on the ground and hooks on the landing gear to engage the mesh.
2015 Summer Series - The NACA - A Hundred Year Legacy

NASA Image and Video Library

2015-07-09

Understanding the past provides insight into our identity and NASA's history lies within NACA, the National Advisory Committee for Aeronautics. NACA's culture of conducting cutting edge research became the spirit of NASA and laid the foundation for America's leap into space. NACA was established on March 3, 1915 in order to promote aeronautical research and was the source behind our air superiority during WWII. The Panel delves into the legacy of the NACA.
Medium fidelity modelling of loads in wind farms under non-neutral ABL stability conditions - a full-scale validation study

NASA Astrophysics Data System (ADS)

Larsen, G. C.; Larsen, T. J.; Chougule, A.

2017-05-01

The aim of the present paper is to demonstrate the capability of medium fidelity modelling of wind turbine component fatigue loading, when the wind turbines are subjected to wake affected non-stationary flow fields under non-neutral atmospheric stability conditions. To accomplish this we combine the classical Dynamic Wake Meandering model with a fundamental conjecture stating: Atmospheric boundary layer stability affects primary wake meandering dynamics driven by large turbulent scales, whereas wake expansion in the meandering frame of reference is hardly affected. Inclusion of stability (i.e. buoyancy) in description of both large- and small scale atmospheric boundary layer turbulence is facilitated by a generalization of the classical Mann spectral tensor, which consistently includes buoyancy effects. With non-stationary wind turbine inflow fields modelled as described above, fatigue loads are obtained using the state-of-the art aeroelastic model HAWC2. The Lillgrund offshore wind farm (WF) constitute an interesting case study for wind farm model validation, because the WT interspacing is small, which in turn means that wake effects are significant. A huge data set, comprising 5 years of blade and tower load recordings, is available for model validation. For a multitude of wake situations this data set displays a considerable scatter, which to a large degree seems to be caused by atmospheric boundary layer stability effects. Notable is also that rotating wind turbine components predominantly experience high fatigue loading for stable stratification with significant shear, whereas high fatigue loading of non-rotating wind turbine components are associated with unstable atmospheric boundary layer stratification.
Selected bibliography of NACA-NASA aircraft icing publications

NASA Technical Reports Server (NTRS)

Reinmann, J. J. (Compiler)

1981-01-01

A summary of NACA-NASA icing research from 1940 to 1962 is presented. It includes: the main results of the NACA icing program from 1940 to 1950; a selected bibliography of 132 NACA-NASA aircraft icing publications; a technical summary of each document cited in the selected bibliography; and a microfiche copy of each document cited in the selected bibliography.
Acoustics Reflections of Full-Scale Rotor Noise Measurements in NFAC 40- by 80-Foot Wind Tunnel

NASA Technical Reports Server (NTRS)

Barbely, Natasha Lydia; Kitaplioglu, Cahit; Sim, Ben W.

2012-01-01

The objective of current research is to identify the extent of acoustic time history distortions due to wind tunnel wall reflections. Acoustic measurements from the recent full-scale Boeing-SMART rotor test (Fig. 2) will be used to illustrate the quality of noise measurement in the NFAC 40- by 80-Foot Wind Tunnel test section. Results will be compared to PSU-WOPWOP predictions obtained with and without adjustments due to sound reflections off wind tunnel walls. Present research assumes a rectangular enclosure as shown in Fig. 3a. The Method of Mirror Images7 is used to account for reflection sources and their acoustic paths by introducing mirror images of the rotor (i.e. acoustic source), at each and every wall surface, to enforce a no-flow boundary condition at the position of the physical walls (Fig. 3b). While conventional approach evaluates the "combined" noise from both the source and image rotor at a single microphone position, an alternative approach is used to simplify implementation of PSU-WOPWOP for this reflection analysis. Here, an "equivalent" microphone position is defined with respect to the source rotor for each mirror image that effectively renders the reflection analysis to be a one rotor, multiple microphones problem. This alternative approach has the advantage of allowing each individual "equivalent" microphone, representing the reflection pulse from the associated wall surface, to be adjusted by the panel absorption coefficient illustrated in Fig. 1a. Note that the presence of parallel wall surfaces requires an infinite number of mirror images (Fig. 3c) to satisfy the no-flow boundary conditions. In the present analysis, up to four mirror images (per wall surface) are accounted to achieve convergence in the predicted time histories
NACA Transonic Wind-tunnel Test Sections

NASA Technical Reports Server (NTRS)

Wright, Ray H; Ward, Vernon G

1955-01-01

Report presents an approximate subsonic theory for the solid-blockage interference in circular wind tunnels with walls slotted in the direction of flow. This theory indicated the possibility of obtaining zero blockage interference. Tests in a circular slotted tunnel based on the theory confirmed the theoretical predictions.
A study of large scale gust generation in a small scale atmospheric wind tunnel with applications to Micro Aerial Vehicles

NASA Astrophysics Data System (ADS)

Roadman, Jason Markos

Modern technology operating in the atmospheric boundary layer can always benefit from more accurate wind tunnel testing. While scaled atmospheric boundary layer tunnels have been well developed, tunnels replicating portions of the atmospheric boundary layer turbulence at full scale are a comparatively new concept. Testing at full-scale Reynolds numbers with full-scale turbulence in an "atmospheric wind tunnel" is sought. Many programs could utilize such a tool including Micro Aerial Vehicle(MAV) development, the wind energy industry, fuel efficient vehicle design, and the study of bird and insect flight, to name just a few. The small scale of MAVs provide the somewhat unique capability of full scale Reynolds number testing in a wind tunnel. However, that same small scale creates interactions under real world flight conditions, atmospheric gusts for example, that lead to a need for testing under more complex flows than the standard uniform flow found in most wind tunnels. It is for these reasons that MAVs are used as the initial testing application for the atmospheric gust tunnel. An analytical model for both discrete gusts and a continuous spectrum of gusts is examined. Then, methods for generating gusts in agreement with that model are investigated. Previously used methods are reviewed and a gust generation apparatus is designed. Expected turbulence and gust characteristics of this apparatus are compared with atmospheric data. The construction of an active "gust generator" for a new atmospheric tunnel is reviewed and the turbulence it generates is measured utilizing single and cross hot wires. Results from this grid are compared to atmospheric turbulence and it is shown that various gust strengths can be produced corresponding to weather ranging from calm to quite gusty. An initial test is performed in the atmospheric wind tunnel whereby the effects of various turbulence conditions on transition and separation on the upper surface of a MAV wing is investigated
Stall behavior of a scaled three-dimensional wind turbine blade

NASA Astrophysics Data System (ADS)

Mulleners, Karen; Melius, Matthew; Cal, Raul Bayoan

2014-11-01

The power generation of a wind turbine is influenced by many factors including the unsteady incoming flow characteristics, pitch regulation, and the geometry of the various turbine components. Within the framework of maximizing energy extraction, it is important to understand and tailor the aerodynamics of a wind turbine. In the interest of seeking further understanding into the complex flow over wind turbine blades, a three-dimensional scaled blade model has been designed and manufactured to be dynamically similar to a rotating full-scale NREL 5MW wind turbine blade. A wind tunnel experiment has been carried out in the 2.2 m × 1.8 m cross-section closed loop wind tunnel at DLR in Göttingen by means of time-resolved stereoscopic PIV. An extensive coherent structure analysis of the time-resolved velocity field over the suction side of the blade was performed to study stall characteristics under a geometrically induced pressure gradient. In particular, the radial extent and propagation of stalled flow regions were characterized for various static angles of attack.
Rotorcraft research testing in the National Full-Scale Aerodynamics Complex at NASA Ames Research Center

NASA Technical Reports Server (NTRS)

Warmbrodt, W.; Smith, C. A.; Johnson, W.

1985-01-01

The unique capabilities of the National Full-Scale Aerodynamics Complex (NFAC) for testing rotorcraft systems are described. The test facilities include the 40- by 80-Foot Wind Tunnel, the 80- by 120-Foot Wind Tunnel, and the Outdoor Aerodynamic Research Facility. The Ames 7- by 10-Foot Subsonic Wind Tunnel is also used in support of the rotor research programs conducted in the NFAC. Detailed descriptions of each of the facilities, with an emphasis on helicopter rotor test capability, are presented. The special purpose rotor test equipment used in conducting helicopter research is reviewed. Test rigs to operate full-scale helicopter main rotors, helicopter tail rotors, and tilting prop-rotors are available, as well as full-scale and small-scale rotor systems for use in various research programs. The test procedures used in conducting rotor experiments are discussed together with representative data obtained from previous test programs. Specific examples are given for rotor performance, loads, acoustics, system interactions, dynamic and aeroelastic stability, and advanced technology and prototype demonstration models.
Flow Visualization Techniques in Wind Tunnel Tests of a Full-Scale F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lanser, Wendy R.; Botha, Gavin J.; James, Kevin D.; Bennett, Mark; Crowder, James P.; Cooper, Don; Olson, Lawrence (Technical Monitor)

1994-01-01

The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. The purpose of the flow-visualization experiments was to document the forebody and leading edge extension (LEX) vortex interaction along with the wing flow patterns at high angles of attack and low speed high Reynolds number conditions. This investigation used surface pressures in addition to both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, LEXS, and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system for three-dimension vortex tracking. The flow visualization experiments were conducted over an angle of attack range from 20 deg to 45 deg and over a sideslip range from -10 deg to 10 deg. The various visualization techniques as well as the pressure distributions were used to understand the flow field structure. The results show regions of attached and separated flow on the forebody, canopy, and wings as well as the vortical flow over the leading-edge extensions. This paper will also present flow visualization comparisons with the F-18 HARV flight vehicle and small-scale oil flows on the F-18.
Altitude Wind Tunnel Drive Motor Installation

NASA Image and Video Library

1943-07-21

Construction workers install the drive motor for the Altitude Wind Tunnel (AWT) in the Exhauster Building at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory. The AWT was capable of operating full-scale engines in air density, speed, and temperature similar to that found at high altitudes. The tunnel could produce wind speeds up to 500 miles per hour through a 20-foot-diameter test section at the standard operating altitude of 30,000 feet. The airflow was created by a large wooden fan near the tunnel’s southeast corner. This photograph shows the installation of the 18,000-horsepower drive motor inside the adjoining Exhauster Building in July 1943. The General Electric motor, whose support frame is seen in this photograph, connected to a drive shaft that extended from the building, through the tunnel shell, and into a 12-bladed, 31-foot-diameter spruce wood fan. Flexible couplings on the shaft allowed for the movement of the shell. The corner of the Exhauster Building was built around the motor after its installation. The General Electric induction motor could produce 10 to 410 revolutions per minute and create wind speeds up to 500 miles per hour, or Mach 0.63, at 30,000 feet. The AWT became operational in January 1944 and tested piston, turbojet and ramjet engines for nearly 20 years.
Loads Correlation of a Full-Scale UH-60A Airloads Rotor in a Wind Tunnel

NASA Technical Reports Server (NTRS)

Yeo, Hyeonsoo; Romander, Ethan A.

2012-01-01

Wind tunnel measurements of the rotor trim, blade airloads, and structural loads of a full-scale UH-60A Black Hawk main rotor are compared with calculations obtained using the comprehensive rotorcraft analysis CAMRAD II and a coupled CAMRAD II/OVERFLOW 2 analysis. A speed sweep at constant lift up to an advance ratio of 0.4 and a thrust sweep at constant speed into deep stall are investigated. The coupled analysis shows significant improvement over comprehensive analysis. Normal force phase is better captured and pitching moment magnitudes are better predicted including the magnitude and phase of the two stall events in the fourth quadrant at the deeply stalled condition. Structural loads are, in general, improved with the coupled analysis, but the magnitude of chord bending moment is still significantly underpredicted. As there are three modes around 4 and 5/rev frequencies, the structural responses to the 5/rev airloads due to dynamic stall are magnified and thus care must be taken in the analysis of the deeply stalled condition.
Full-scale wind-tunnel investigation of the effects of wing leading-edge modifications on the high angle-of-attack aerodynamic characteristics of a low-wing general aviation airplane

NASA Technical Reports Server (NTRS)

Johnson, J. L., Jr.; Newsom, W. A.; Satran, D. R.

1980-01-01

The paper presents the results of a recent investigation to determine the effects of wing leading-edge modifications on the high angle-of-attack aerodynamic characteristics of a low-wing general aviation airplane in the Langley Full-Scale Wind Tunnel. The investigation was conducted to provide aerodynamic information for correlation and analysis of flight-test results obtained for the configuration. The wind-tunnel investigation consisted of force and moment measurements, wing pressure measurements, flow surveys, and flow visualization studies utilizing a tuft grid, smoke and nonintrusive mini-tufts which were illuminated by ultra-violet light. In addition to the tunnel scale system which measured overall forces and moments, the model was equipped with an auxiliary strain-gage balance within the left wing panel to measure lift and drag forces on the outer wing panel independent of the tunnel scale system. The leading-edge modifications studied included partial- and full-span leading-edge droop arrangements as well as leading-edge slats.
NACA Subcommittee on Combustion Meeting

NASA Image and Video Library

1951-12-21

The National Advisory Committee for Aeronautics (NACA) Subcommittee on Combustion holds a meeting at Lewis Flight Propulsion Laboratory in Cleveland, Ohio. The NACA was managed by committees that included members of their own staff along with representatives from industry, the military, other government agencies, and universities. The 17-person Executive Committee was the NACA’s primary administrative body. They met several times a year at the NACA headquarters office in Washington DC to discuss broad issues confronting the US aeronautical community. Jerome Hunsaker, head of the Department of Aeronautical Engineering at the Massachusetts Institute of Technology, served as the NACA chairman from 1941 to 1956. George Lewis was not a member of the Executive Committee but served a key role as the NACA’s Director of Aeronautical Research. The NACA’s organizational chart also included 11 technical committees, several of which had specialized subcommittees. There were over 100 different subcommittees between World War I and 1958. The number of active subcommittees varied over the years. Most existed only for a few years, but some continued for over a decade. The subcommittees met three or four times per year, often at the laboratory most closely associated with the area of research. A team of laboratory researchers presented briefings on their recent activities and plans for the future. The Subcommittee on Combustion existed from 1945 to the NACA’s demise in 1958.

Wind-Tunnel Investigation of an NACA 23021 Airfoil with a 0.32-Airfoil-Chord Double Slotted Flap

NASA Technical Reports Server (NTRS)

Fischel, Jack; Riebe, John M

1944-01-01

An investigation was made in the LMAL 7- by 10-foot wind tunnel of a NACA 23021 airfoil with a double slotted flap having a chord 32 percent of the airfoil chord (0.32c) to determine the aerodynamic section characteristics with the flaps deflected at various positions. The effects of moving the fore flap and rear flap as a unit and of deflecting or removing the lower lip of the slot were also determined. Three positions were selected for the fore flap and at each position the maximum lift of the airfoil was obtained with the rear flap at the maximum deflection used at that fore-flap position. The section lift of the airfoil increased as the fore flap was extended and maximum lift was obtained with the fore flap deflected 30 deg in the most extended position. This arrangement provided a maximum section lift coefficient of 3.31, which was higher than the value obtained with either a 0.2566c or a 0.40c single-slotted-flap arrangement and 0.25 less than the value obtained with a 0.4c double-slotted-flap arrangement on the same airfoil. The values of the profile-drag coefficient obtained with the 0.32c double slotted flap were larger than those for the 0.2566c or 0.40c single slotted flaps for section lift coefficients between 1.0 and approximately 2.7. At all values of the section lift coefficient above 1.0, the 0.40c double slotted flap had a lower profile drag than the 0.32c double slotted flap. At various values of the maximum section lift coefficient produced by various flap defections, the 0.32c double slotted flap gave negative section pitching-moment coefficients that were higher than those of other slotted flaps on the same airfoil. The 0.32c double slotted flap gave approximately the same maximum section lift coefficient as, but higher profile-drag coefficients over the entire lift range than, a similar arrangement of a 0.30c double slotted flap on an NACA 23012 airfoil.
Wind Tunnel to Atmospheric Mapping for Static Aeroelastic Scaling

NASA Technical Reports Server (NTRS)

Heeg, Jennifer; Spain, Charles V.; Rivera, J. A.

2004-01-01

Wind tunnel to Atmospheric Mapping (WAM) is a methodology for scaling and testing a static aeroelastic wind tunnel model. The WAM procedure employs scaling laws to define a wind tunnel model and wind tunnel test points such that the static aeroelastic flight test data and wind tunnel data will be correlated throughout the test envelopes. This methodology extends the notion that a single test condition - combination of Mach number and dynamic pressure - can be matched by wind tunnel data. The primary requirements for affecting this extension are matching flight Mach numbers, maintaining a constant dynamic pressure scale factor and setting the dynamic pressure scale factor in accordance with the stiffness scale factor. The scaling is enabled by capabilities of the NASA Langley Transonic Dynamics Tunnel (TDT) and by relaxation of scaling requirements present in the dynamic problem that are not critical to the static aeroelastic problem. The methodology is exercised in two example scaling problems: an arbitrarily scaled wing and a practical application to the scaling of the Active Aeroelastic Wing flight vehicle for testing in the TDT.
Index of NACA Technical Publications, 1949 - May, 1951

NASA Technical Reports Server (NTRS)

1952-01-01

The Preface to the Index of NACA Technical Publications, 1915-1949, mentioned that regular supplements would be issued in the future. This is the first such Supplement and covers those documents issued through May of 1951. Similar arrangement is used in both Indexes. First, there is a classified listing of the subject categories; second, a chronological listing of NACA publications under each subject category; third, an alphabetical index to the subject categories; and finally, an author index. The latter feature was not included in the basic 1915-1949 Index but has been issued separately and is available upon request. Immediately following this Preface is an Explanatory Chart of NACA Publications Series Designations which may be of use in identifying references to NACA documents encountered in the literature.
Scale effects in wind tunnel modeling of an urban atmospheric boundary layer

NASA Astrophysics Data System (ADS)

Kozmar, Hrvoje

2010-03-01

Precise urban atmospheric boundary layer (ABL) wind tunnel simulations are essential for a wide variety of atmospheric studies in built-up environments including wind loading of structures and air pollutant dispersion. One of key issues in addressing these problems is a proper choice of simulation length scale. In this study, an urban ABL was reproduced in a boundary layer wind tunnel at different scales to study possible scale effects. Two full-depth simulations and one part-depth simulation were carried out using castellated barrier wall, vortex generators, and a fetch of roughness elements. Redesigned “Counihan” vortex generators were employed in the part-depth ABL simulation. A hot-wire anemometry system was used to measure mean velocity and velocity fluctuations. Experimental results are presented as mean velocity, turbulence intensity, Reynolds stress, integral length scale of turbulence, and power spectral density of velocity fluctuations. Results suggest that variations in length-scale factor do not influence the generated ABL models when using similarity criteria applied in this study. Part-depth ABL simulation compares well with two full-depth ABL simulations indicating the truncated vortex generators developed for this study can be successfully employed in urban ABL part-depth simulations.
A restored NACA P-51D Mustang in flight

NASA Image and Video Library

2000-09-15

The huge compass rose on Rogers Dry Lake formed a backdrop for a genuine NACA (National Advisory Committee for Aeronautics) P-51D Mustang owned and flown by William C. Allmon during a visit to the NASA Dryden Flight Research Center in California's Mojave Desert Sept. 15, 2000 for a reunion of former NACA employees. The NACA was the forerunner of NASA.
Voltage Impacts of Utility-Scale Distributed Wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, A.

2014-09-01

Although most utility-scale wind turbines in the United States are added at the transmission level in large wind power plants, distributed wind power offers an alternative that could increase the overall wind power penetration without the need for additional transmission. This report examines the distribution feeder-level voltage issues that can arise when adding utility-scale wind turbines to the distribution system. Four of the Pacific Northwest National Laboratory taxonomy feeders were examined in detail to study the voltage issues associated with adding wind turbines at different distances from the sub-station. General rules relating feeder resistance up to the point of turbinemore » interconnection to the expected maximum voltage change levels were developed. Additional analysis examined line and transformer overvoltage conditions.« less
NACA Muroc Staff of 1949 at NACA barbecue

NASA Technical Reports Server (NTRS)

1949-01-01

On a nice day in November 1949 the NACA High-Speed Flight Station employees enjoy a break from a week of research by attending a barbecue on the Rawliegh Duntley ranch. The food was excellent and the camaraderie with friends and family members was welcome. Games were played with the winners applauded--fun for everyone before the start of another week.
Altitude Wind Tunnel Control Room

NASA Image and Video Library

1945-05-21

Researchers at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory monitor a ramjet's performance in the Altitude Wind Tunnel from the control room. The soundproof control room was just a few feet from the tunnel’s 20-foot-diameter test section. In the control room, the operators could control all aspects of the tunnel’s operation, including the air density, temperature, and speed. They also operated the engine or test article in the test section by controlling the angle-of-attack, speed, power, and other parameters. The men in this photograph are monitoring the engine’s thrust and lift. A NACA-designed 20-inch-diameter ramjet was installed in the tunnel in May 1945. Thrust figures from these runs were compared with drag data from tests of scale models in small supersonic tunnels to verify the ramjet’s feasibility. The tunnel was used to analyze the ramjet’s overall performance up to altitudes of 47,000 feet and speeds to Mach 1.84. The researchers found that an increase in altitude caused a reduction in the engine’s horsepower and identified optimal flameholder configurations.
A Study of the Effects of Large Scale Gust Generation in a Small Scale Atmospheric Wind Tunnel: Application to Micro Aerial Vehicles

NASA Astrophysics Data System (ADS)

Roadman, Jason; Mohseni, Kamran

2009-11-01

Modern technology operating in the atmospheric boundary layer could benefit from more accurate wind tunnel testing. While scaled atmospheric boundary layer tunnels have been well developed, tunnels replicating portions of the turbulence of the atmospheric boundary layer at full scale are a comparatively new concept. Testing at full-scale Reynolds numbers with full-scale turbulence in an ``atmospheric wind tunnel'' is sought. Many programs could utilize such a tool including that of Micro Aerial Vehicles (MAVs) and other unmanned aircraft, the wind energy industry, fuel efficient vehicles, and the study of bird and insect fight. The construction of an active ``gust generator'' for a new atmospheric tunnel is reviewed and the turbulence it generates is measured utilizing single and cross hot wires. Results from this grid are compared to atmospheric turbulence and it is shown that various gust strengths can be produced corresponding to days ranging from calm to quite gusty. An initial test is performed in the atmospheric wind tunnel whereby the effects of various turbulence conditions on transition and separation on the upper surface of a MAV wing is investigated using oil flow visualization.
Airframe Noise Prediction of a Full Aircraft in Model and Full Scale Using a Lattice Boltzmann Approach

NASA Technical Reports Server (NTRS)

Fares, Ehab; Duda, Benjamin; Khorrami, Mehdi R.

2016-01-01

Unsteady flow computations are presented for a Gulfstream aircraft model in landing configuration, i.e., flap deflected 39deg and main landing gear deployed. The simulations employ the lattice Boltzmann solver PowerFLOW(Trademark) to simultaneously capture the flow physics and acoustics in the near field. Sound propagation to the far field is obtained using a Ffowcs Williams and Hawkings acoustic analogy approach. Two geometry representations of the same aircraft are analyzed: an 18% scale, high-fidelity, semi-span model at wind tunnel Reynolds number and a full-scale, full-span model at half-flight Reynolds number. Previously published and newly generated model-scale results are presented; all full-scale data are disclosed here for the first time. Reynolds number and geometrical fidelity effects are carefully examined to discern aerodynamic and aeroacoustic trends with a special focus on the scaling of surface pressure fluctuations and farfield noise. An additional study of the effects of geometrical detail on farfield noise is also documented. The present investigation reveals that, overall, the model-scale and full-scale aeroacoustic results compare rather well. Nevertheless, the study also highlights that finer geometrical details that are typically not captured at model scales can have a non-negligible contribution to the farfield noise signature.
Aeronautics in NACA and NASA

NASA Technical Reports Server (NTRS)

1991-01-01

Initiated in 1915, the National Advisory Committee for Aeronautics/National Aeronautics and Space Administration (NACA/NASA) aeronautical programs have been the keystone of a sustained U.S. Government, industry, and university research effort which has been a primary factor in the development of our remarkable air transportation systems, the country's largest positive trade balance component, and the world's finest military Air Force. This overview summarizes the flow of events, and the major trends, that have led from the NACA origins to the present NASA Aeronautics program, and indicates some important directions for the years ahead.
Scaling forecast models for wind turbulence and wind turbine power intermittency

NASA Astrophysics Data System (ADS)

Duran Medina, Olmo; Schmitt, Francois G.; Calif, Rudy

2017-04-01

The intermittency of the wind turbine power remains an important issue for the massive development of this renewable energy. The energy peaks injected in the electric grid produce difficulties in the energy distribution management. Hence, a correct forecast of the wind power in the short and middle term is needed due to the high unpredictability of the intermittency phenomenon. We consider a statistical approach through the analysis and characterization of stochastic fluctuations. The theoretical framework is the multifractal modelisation of wind velocity fluctuations. Here, we consider three wind turbine data where two possess a direct drive technology. Those turbines are producing energy in real exploitation conditions and allow to test our forecast models of power production at a different time horizons. Two forecast models were developed based on two physical principles observed in the wind and the power time series: the scaling properties on the one hand and the intermittency in the wind power increments on the other. The first tool is related to the intermittency through a multifractal lognormal fit of the power fluctuations. The second tool is based on an analogy of the power scaling properties with a fractional brownian motion. Indeed, an inner long-term memory is found in both time series. Both models show encouraging results since a correct tendency of the signal is respected over different time scales. Those tools are first steps to a search of efficient forecasting approaches for grid adaptation facing the wind energy fluctuations.
Hover test of a full-scale hingeless helicopter rotor: Aeroelastic stability, performance and loads data. [wind tunnel tests

NASA Technical Reports Server (NTRS)

Peterson, R. L.; Warmbrodt, W.

1984-01-01

A hover test of a full-scale, hingeless rotor system was conducted in the NASA Ames 40- by 80-foot wind tunnel. The rotor was tested on the Ames rotor test apparatus. Rotor aeroelastic stability, performance, and loads at various rotational speeds and thrust coefficients were investigated. The primary objective was to determine the inplane stability characteristics of the rotor system. Rotor inplane damping data were obtained for operation between 350 and 425 rpm (design speed), and for thurst coefficients between 0.0 and 0.12. The rotor was stable for all conditions tested. At constant rotor rotational speed, a minimum inplane dampling level was obtained at a thrust coefficient approximately = 0.02. At constant rotor lift, a minimum in rotor inplane damping was measured at 400 rpm.
Groundbreaking Ceremony at the NACA's Plum Brook Station

NASA Image and Video Library

1956-09-21

Addison Rothrock, the National Advisory Committee for Aeronautics’s (NACA) Assistant Director of Research, speaks at the groundbreaking ceremony for the Lewis Flight Propulsion Laboratory’s new test reactor at Plum Brook Station. This dedication event was held almost exactly one year after the NACA announced that it would build its $4.5 million nuclear reactor on 500 acres of the army’s 9000-acre Plum Brook Ordnance Works. The site was located in Sandusky, Ohio, approximately 60 miles west of the NACA Lewis laboratory in Cleveland. Lewis Director Raymond Sharp is seated to the left of Rothrock, Congressman Albert Baumhart and NACA Secretary John Victory are to the right. Many government and local officials were on hand for the press conference and ensuing luncheon. In the wake of World War II the military, the Atomic Energy Commission, and the NACA became interested in the use of atomic energy for propulsion and power. A Nuclear Division was established at NACA Lewis in the early 1950s. The division’s request for a 60-megawatt research reactor was approved in 1955. The semi-remote Plum Brook location was selected over 17 other possible sites. Construction of the Plum Brook Reactor Facility lasted five years. By the time of its first trial runs in 1961 the aircraft nuclear propulsion program had been cancelled. The space age had arrived, however, and the reactor would be used to study materials for a nuclear powered rocket.
Aeroacoustic measurements on a NACA 0012 applying the Coherent Particle Velocity method

NASA Astrophysics Data System (ADS)

Plogmann, B.; Würz, W.

2013-07-01

Aeroacoustic measurements on two NACA 0012 airfoil sections with different chord length and sharp trailing edge were conducted at the Laminar Wind Tunnel (LWT) of the University of Stuttgart. The LWT is a closed test section wind tunnel with a very low turbulence level and an acoustically optimized diffusor section allowing for high-quality aerodynamic as well as aeroacoustic measurements. Trailing edge noise measurements were performed using the Coherent Particle Velocity (CPV) method, which is based on a cross-spectral analysis of two hot-wire sensor signals placed on the suction and the pressure side of the airfoil trailing edge, respectively. At high angles of attack, the cross-spectral analysis of the two sensor signals used for the measurement of the trailing edge noise can be prone to a disturbing influence of hydrodynamic fluctuations. Hence, continuous shifts in the phasing of the cross-correlation are observed mainly for low sensor distances to the trailing edge. The quantitative evaluation of the trailing edge noise predominately in the low frequency range is, therefore, considerably disturbed. A new approach is proposed, which allows for the correction of the cross-correlation function based on the averaged single wire auto-spectrum. The results are compared to measurements with increased sensor distance and show good agreement. In the following, trailing edge noise measurements were performed on a NACA 0012 airfoil in a wide range of angles of attack ( α = 0°-8°) and free-stream velocities (u_{infty} = 30{-}70 {{m/s}}). The tripped flow cases exhibit a very good consistency for the scaling of the 1/3 octave spectra based on outer variables. Moreover, a common intersection point of the sound pressure level was observed for trailing edge noise spectra measured at constant free-stream velocity and different angles of attack. In cases without boundary layer tripping, the presence of an acoustic feedback loop was observed and linked to the presence of a
Re-Computation of Numerical Results Contained in NACA Report No. 496

NASA Technical Reports Server (NTRS)

Perry, Boyd, III

2015-01-01

An extensive examination of NACA Report No. 496 (NACA 496), "General Theory of Aerodynamic Instability and the Mechanism of Flutter," by Theodore Theodorsen, is described. The examination included checking equations and solution methods and re-computing interim quantities and all numerical examples in NACA 496. The checks revealed that NACA 496 contains computational shortcuts (time- and effort-saving devices for engineers of the time) and clever artifices (employed in its solution methods), but, unfortunately, also contains numerous tripping points (aspects of NACA 496 that have the potential to cause confusion) and some errors. The re-computations were performed employing the methods and procedures described in NACA 496, but using modern computational tools. With some exceptions, the magnitudes and trends of the original results were in fair-to-very-good agreement with the re-computed results. The exceptions included what are speculated to be computational errors in the original in some instances and transcription errors in the original in others. Independent flutter calculations were performed and, in all cases, including those where the original and re-computed results differed significantly, were in excellent agreement with the re-computed results. Appendix A contains NACA 496; Appendix B contains a Matlab(Reistered) program that performs the re-computation of results; Appendix C presents three alternate solution methods, with examples, for the two-degree-of-freedom solution method of NACA 496; Appendix D contains the three-degree-of-freedom solution method (outlined in NACA 496 but never implemented), with examples.
Blade Displacement Measurement Technique Applied to a Full-Scale Rotor Test

NASA Technical Reports Server (NTRS)

Abrego, Anita I.; Olson, Lawrence E.; Romander, Ethan A.; Barrows, Danny A.; Burner, Alpheus W.

2012-01-01

Blade displacement measurements using multi-camera photogrammetry were acquired during the full-scale wind tunnel test of the UH-60A Airloads rotor, conducted in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel. The objectives were to measure the blade displacement and deformation of the four rotor blades as they rotated through the entire rotor azimuth. These measurements are expected to provide a unique dataset to aid in the development and validation of rotorcraft prediction techniques. They are used to resolve the blade shape and position, including pitch, flap, lag and elastic deformation. Photogrammetric data encompass advance ratios from 0.15 to slowed rotor simulations of 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. An overview of the blade displacement measurement methodology and system development, descriptions of image processing, uncertainty considerations, preliminary results covering static and moderate advance ratio test conditions and future considerations are presented. Comparisons of experimental and computational results for a moderate advance ratio forward flight condition show good trend agreements, but also indicate significant mean discrepancies in lag and elastic twist. Blade displacement pitch measurements agree well with both the wind tunnel commanded and measured values.
Experimental characterization of turbulent inflow noise on a full-scale wind turbine

NASA Astrophysics Data System (ADS)

Buck, Steven; Oerlemans, Stefan; Palo, Scott

2016-12-01

An extensive experimental campaign was conducted on a 108-m diameter 2.3-MW wind turbine in order to assess the effect of inflow turbulence conditions on wind turbine acoustics. Over 50 h of continuous acoustic data was acquired at power-generating wind speeds. Twelve precision microphones were used, arranged in a one rotor radius ring about the turbine tower in order to assess the directivity of the noise emission. Turbine operational and atmospheric conditions were gathered simultaneously with acoustics measurements. The testing and analysis constitute perhaps the most thorough experimental characterization of turbulent inflow noise from a wind turbine to date. Turbulence intensities typically varied between 10 percent and 35 percent, and wind speeds covered most of the operational range of the wind turbine, from cut-on to well above its rated power. A method was developed for using blade-mounted accelerometers for determining the turbulence conditions in the immediate vicinity of the blades, which are the primary turbulence noise generating bodies. The method uses the blades' vibrational energy within a specified frequency range to estimate the overall turbulence conditions by assuming a von Kármán turbulence spectrum. Using this method, a clear positive correlation is shown between turbulence intensity and noise levels. The turbulence noise is dominant at low frequencies and is primarily observed in the upwind and downwind directions. Low frequency noise increases by as much as 6 dB for the range of turbulence conditions measured. Comparisons are made between the measured turbine noise directivity and theory using a simple acoustic model of the turbine as three point-sources. Strong agreement is found between the theoretical leading edge noise directivity model and the measured low frequency noise directivity.
A comparative analysis between NACA 4412 airfoil and it's modified form with tubercles

NASA Astrophysics Data System (ADS)

Hasan, Md. Jonayed; Islam, Md. Tazul; Hassan, Md. Mehedi

2017-06-01

The effect of tubercles on the leading edge of an airfoil become more vivid at high angle of attacks. The effect of tubercles with large wavelength and small amplitude on the leading edge of a NACA 4412 airfoil section was investigated numerically and experimentally. The phenomena of improving the airfoil performance by modifying the contours drove our interest to do this analysis. The models were developed & numerical simulations were carried out with both NACA 4412 airfoil and modified airfoil model at Re=1.03×106 and angles of attack ranging from 0° to 20°. Flow separation was analyzed with vector profiles. CL, CD at different angle of attacks was developed and it gave down noticeable pre-stall & post-stall behavior. The airfoils were studied experimentally in a low speed wind tunnel. Pressure distribution over the two airfoils was obtained. It was evident from the pressure distributions that the modified airfoil exhibits significant aerodynamic performance at high angles of attack. We can infer that these effects will be advantageous for maneuverability and post-stall behavior.
Correlating CFD Simulation with Wind Tunnel Test for the Full-Scale UH-60A Airloads Rotor

NASA Technical Reports Server (NTRS)

Romandr, Ethan; Norman, Thomas R.; Chang, I-Chung

2011-01-01

Data from the recent UH-60A Airloads Test in the National Full-Scale Aerodynamics Complex 40- by 80- Foot Wind Tunnel at NASA Ames Research Center are presented and compared to predictions computed by a loosely coupled Computational Fluid Dynamics (CFD)/Comprehensive analysis. Primary calculations model the rotor in free-air, but initial calculations are presented including a model of the tunnel test section. The conditions studied include a speed sweep at constant lift up to an advance ratio of 0.4 and a thrust sweep at constant speed into deep stall. Predictions show reasonable agreement with measurement for integrated performance indicators such as power and propulsive but occasionally deviate significantly. Detailed analysis of sectional airloads reveals good correlation in overall trends for normal force and pitching moment but pitching moment mean often differs. Chord force is frequently plagued by mean shifts and an overprediction of drag on the advancing side. Locations of significant aerodynamic phenomena are predicted accurately although the magnitude of individual events is often missed.

Scaling Characteristics of Mesoscale Wind Fields in the Lower Atmospheric Boundary Layer: Implications for Wind Energy

NASA Astrophysics Data System (ADS)

Kiliyanpilakkil, Velayudhan Praju

Atmospheric motions take place in spatial scales of sub-millimeters to few thousands of kilometers with temporal changes in the atmospheric variables occur in fractions of seconds to several years. Consequently, the variations in atmospheric kinetic energy associated with these atmospheric motions span over a broad spectrum of space and time. The mesoscale region acts as an energy transferring regime between the energy generating synoptic scale and the energy dissipating microscale. Therefore, the scaling characterizations of mesoscale wind fields are significant in the accurate estimation of the atmospheric energy budget. Moreover, the precise knowledge of the scaling characteristics of atmospheric mesoscale wind fields is important for the validation of the numerical models those focus on wind forecasting, dispersion, diffusion, horizontal transport, and optical turbulence. For these reasons, extensive studies have been conducted in the past to characterize the mesoscale wind fields. Nevertheless, the majority of these studies focused on near-surface and upper atmosphere mesoscale regimes. The present study attempt to identify the existence and to quantify the scaling of mesoscale wind fields in the lower atmospheric boundary layer (ABL; in the wind turbine layer) using wind observations from various research-grade instruments (e.g., sodars, anemometers). The scaling characteristics of the mesoscale wind speeds over diverse homogeneous flat terrains, conducted using structure function based analysis, revealed an altitudinal dependence of the scaling exponents. This altitudinal dependence of the wind speed scaling may be attributed to the buoyancy forcing. Subsequently, we use the framework of extended self-similarity (ESS) to characterize the observed scaling behavior. In the ESS framework, the relative scaling exponents of the mesoscale atmospheric boundary layer wind speed exhibit quasi-universal behavior; even far beyond the inertial range of turbulence (Delta
Full-scale fatigue tests of CX-100 wind turbine blades. Part I: testing

NASA Astrophysics Data System (ADS)

Farinholt, Kevin M.; Taylor, Stuart G.; Park, Gyuhae; Ammerman, Curtt M.

2012-04-01

This paper overviews the test setup and experimental methods for structural health monitoring (SHM) of two 9-meter CX-100 wind turbine blades that underwent fatigue loading at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC). The first blade was a pristine blade, which was manufactured to standard specifications for the CX-100 design. The second blade was manufactured for the University of Massachusetts, Lowell with intentional simulated defects within the fabric layup. Each blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. The blades underwent harmonic excitation at their first natural frequency using the Universal Resonant Excitation (UREX) system at NREL. Blades were initially excited at 25% of their design load, and then with steadily increasing loads until each blade reached failure. Data from the sensors were collected between and during fatigue loading sessions. The data were measured over multi-scale frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed at Los Alamos National Laboratory (LANL). The hardware systems were evaluated for their aptness in data collection for effective application of SHM methods to the blades. The results of this assessment will inform the selection of acquisition hardware and sensor types to be deployed on a CX-100 flight test to be conducted in collaboration with Sandia National Laboratory at the U.S. Department of Agriculture's (USDA) Conservation and Production Research Laboratory (CPRL) in Bushland, Texas.
Test data report: Low speed wind tunnel tests of a full scale, fixed geometry inlet, with engine, at high angles of attack

NASA Technical Reports Server (NTRS)

Shain, W. M.

1976-01-01

A full scale inlet test was to be done in the NASA-ARC 40' X 80' WT to demonstrate satisfactory inlet performance at high angles of attack. The inlet was designed to match a Hamilton-Standard 55 inch, variable pitch fan, driven by a Lycoming T55-L-11A gas generator. The test was installed in the wind tunnel on two separate occasions, but mechanical failures in the fan drive gear box early in each period terminated testing. A detailed description is included of the Model, installation, instrumentation and data reduction procedures.
Free-Spinning-Tunnel Investigation of a 1/28-Scale Model of the North American FJ-4 Airplane with External Fuel Tanks, TED No. NACA AD 3112

NASA Technical Reports Server (NTRS)

Healy, Frederick M.

1958-01-01

A supplementary investigation to determine the effect of external fuel tanks on the spin and recovery characteristics of a l/28-scale model of the North American FJ-4 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The model had been extensively tested previously (NACA Research Memorandum SL38A29) and therefore only brief tests were made to evaluate the effect of tank installation. Erect spin tests of the model indicate that flat-type spins-are more prevalent with 200-gallon external fuel tanks than with tanks not installed. The recovery technique determined for spins without tanks, rudder reversal to full against the spin accompanied by simultaneous movement of ailerons to full with the spin, is recommended for spins encountered with external tanks installed. If inverted spins are encountered with external tanks installed, the tanks should be jettisoned and recovery attempted by rudder reversal to full against the spin with ailerons maintained at neutral.
Wall-interference assessment and corrections for transonic NACA 0012 airfoil data from various wind tunnels. M.S. Thesis - George Washington Univ., 1988

NASA Technical Reports Server (NTRS)

Green, Lawrence L.; Newman, Perry A.

1991-01-01

A nonlinear, four wall, post-test wall interference assessment/correction (WIAC) code was developed for transonic airfoil data from solid wall wind tunnels with flexibly adaptable top and bottom walls. The WIAC code was applied over a broad range of test conditions to four sets of NACA 0012 airfoil data, from two different adaptive wall wind tunnels. The data include many test points for fully adapted walls, as well as numerous partially adapted and unadapted test points, which together represent many different model/tunnel configurations and possible wall interference effects. Small corrections to the measured Mach numbers and angles of attack were obtained from the WIAC code even for fully adapted data; these corrections generally improve the correlation among the various sets of airfoil data and simultaneously improve the correlation of the data with calculations for a 2-D, free air, Navier-Stokes code. The WIAC corrections for airfoil data taken in fully adapted wall test sections are shown to be significantly smaller than those for comparable airfoil data from straight, slotted wall test sections. This indicates, as expected, a lesser degree of wall interference in the adapted wall tunnels relative to the slotted wall tunnels. Application of the WIAC code to this data was, however, somewhat more difficult and time consuming than initially expected from similar previous experience with WIAC applications to slotted wall data.
Blade Displacement Measurements of the Full-Scale UH-60A Airloads Rotor

NASA Technical Reports Server (NTRS)

Barrows, Danny A.; Burner, Alpheus W.; Abrego, Anita I.; Olson, Lawrence E.

2011-01-01

Blade displacement measurements were acquired during a wind tunnel test of the full-scale UH-60A Airloads rotor. The test was conducted in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at NASA Ames Research Center. Multi-camera photogrammetry was used to measure the blade displacements of the four-bladed rotor. These measurements encompass a range of test conditions that include advance ratios from 0.15 to unique slowed-rotor simulations as high as 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective of these measurements is to provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft computational tools. The methodology, system development, measurement techniques, and preliminary sample blade displacement measurements are presented.
NACA Computer at the Lewis Flight Propulsion Laboratory

NASA Image and Video Library

1951-02-21

A female computer at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory with a slide rule and Friden adding machine to make computations. The computer staff was introduced during World War II to relieve short-handed research engineers of some of the tedious computational work. The Computing Section was staffed by “computers,” young female employees, who often worked overnight when most of the tests were run. The computers obtained test data from the manometers and other instruments, made the initial computations, and plotted the data graphically. Researchers then analyzed the data and summarized the findings in a report or made modifications and ran the test again. There were over 400 female employees at the laboratory in 1944, including 100 computers. The use of computers was originally planned only for the duration of the war. The system was so successful that it was extended into the 1960s. The computers and analysts were located in the Altitude Wind Tunnel Shop and Office Building office wing during the 1940s and transferred to the new 8- by 6-Foot Supersonic Wind Tunnel in 1948.
Full-scale Wind-tunnel to Determine a Satisfactory Location for a Service Pitot-static Tube on a Low-wing Monoplane

NASA Technical Reports Server (NTRS)

Parsons, John F

1936-01-01

Surveys of the air flow over the upper surface of four different airfoils were made in the full-scale wind tunnel to determine a satisfactory location for a fixed Pitot-static tube on a low-wing monoplane. The selection was based on small interference errors, less than 5 percent, and on a consideration of structural and ground handling problems. The most satisfactory location on the airfoils without flaps that were investigated was 10 percent of the chord aft and 25 percent of the chord above the trailing edge of a section approximately 40 percent of the semispan inboard of the wing tip. No satisfactory location was found near the wing when the flaps were deflected.
Index of Naca Technical Publications, June 1953 - May 1954

NASA Technical Reports Server (NTRS)

1954-01-01

The Preface to the Index of NACA Technical Publications, 1915 - 1949, mentioned that regular supplements would be issued in the future. This is the third such Supplement and covers those documents issued from June 1953 through May 1954. Also included are certain documents dated prior to June 1953 which have been declassified during the period covered by this supplement. Similar arrangement is used in these Indexes. First, there is a classified listing of the subject categories; second, a chronological listing of NACA publications under each subject category; third, an alphabetical index to the subject categories; and finally, an author index. Immediately following this Preface is an Explanatory Chart of NACA Publications Series Designations which may be of use in identifying references to NACA research reports encountered in the literature.
Full-field inspection of a wind turbine blade using three-dimensional digital image correlation

NASA Astrophysics Data System (ADS)

LeBlanc, Bruce; Niezrecki, Christopher; Avitabile, Peter; Chen, Julie; Sherwood, James; Hughes, Scott

2011-04-01

Increasing demand and deployment of wind power has led to a significant increase in the number of wind-turbine blades manufactured globally. As the physical size and number of turbines deployed grows, the probability of manufacturing defects being present in composite turbine blade fleets also increases. As both capital blade costs, and operational and maintenance costs, increase for larger turbine systems the need for large-scale inspection and monitoring of the state of structural health of turbine blades during manufacturing and operation critically increase. One method for locating and quantifying manufacturing defects, while also allowing for the in-situ measurement of the structural health of blades, is through the observation of the full-field state of deformation and strain of the blade. Static tests were performed on a nine-meter CX-100 composite turbine blade to extract full-field displacement and strain measurements using threedimensional digital image correlation (3D DIC). Measurements were taken at several angles near the blade root, including along the high-pressure surface, low-pressure surface, and along the trailing edge of the blade. The overall results indicate that the measurement approach can clearly identify failure locations and discontinuities in the blade curvature under load. Post-processing of the data using a stitching technique enables the shape and curvature of the entire blade to be observed for a large-scale wind turbine blade for the first time. The experiment demonstrates the feasibility of the approach and reveals that the technique readily can be scaled up to accommodate utility-scale blades. As long as a trackable pattern is applied to the surface of the blade, measurements can be made in-situ when a blade is on a manufacturing floor, installed in a test fixture, or installed on a rotating turbine. The results demonstrate the great potential of the optical measurement technique and its capability for use in the wind industry for
NACA Photographer North American F-100A (NACA-200) Super Sabre Airplane take-off. The blowing-tupe

NASA Technical Reports Server (NTRS)

1957-01-01

NACA Photographer North American F-100A (NACA-200) Super Sabre Airplane take-off. The blowing-tupe boundary-layer control on the leading- and trailing-edge provided large reductions in takeoff and landing approach speeds. Approach speeds were reduced by about 10 knots (Mar 1960). Note: Used in publication in Flight Research at Ames; 57 Years of Development and Validation of Aeronautical Technology NASA SP-1998-3300 fig. 102 and and Memoirs of a Flight Test Engneer NASA SP-2002-4525
Fluid-structure interaction modeling of wind turbines: simulating the full machine

NASA Astrophysics Data System (ADS)

Hsu, Ming-Chen; Bazilevs, Yuri

2012-12-01

In this paper we present our aerodynamics and fluid-structure interaction (FSI) computational techniques that enable dynamic, fully coupled, 3D FSI simulation of wind turbines at full scale, and in the presence of the nacelle and tower (i.e., simulation of the "full machine"). For the interaction of wind and flexible blades we employ a nonmatching interface discretization approach, where the aerodynamics is computed using a low-order finite-element-based ALE-VMS technique, while the rotor blades are modeled as thin composite shells discretized using NURBS-based isogeometric analysis (IGA). We find that coupling FEM and IGA in this manner gives a good combination of efficiency, accuracy, and flexibility of the computational procedures for wind turbine FSI. The interaction between the rotor and tower is handled using a non-overlapping sliding-interface approach, where both moving- and stationary-domain formulations of aerodynamics are employed. At the fluid-structure and sliding interfaces, the kinematic and traction continuity is enforced weakly, which is a key ingredient of the proposed numerical methodology. We present several simulations of a three-blade 5~MW wind turbine, with and without the tower. We find that, in the case of no tower, the presence of the sliding interface has no effect on the prediction of aerodynamic loads on the rotor. From this we conclude that weak enforcement of the kinematics gives just as accurate results as the strong enforcement, and thus enables the simulation of rotor-tower interaction (as well as other applications involving mechanical components in relative motion). We also find that the blade passing the tower produces a 10-12 % drop (per blade) in the aerodynamic torque. We feel this finding may be important when it comes to the fatigue-life analysis and prediction for wind turbine blades.
Aerodynamic characteristics of three helicopter rotor airfoil sections at Reynolds number from model scale to full scale at Mach numbers from 0.35 to 0.90. [conducted in Langley 6 by 28 inch transonic tunnel

NASA Technical Reports Server (NTRS)

Noonan, K. W.; Bingham, G. J.

1980-01-01

An investigation was conducted in the Langely 6 by 28 inch transonic tunnel to determine the two dimensional aerodynamic characteristics of three helicopter rotor airfoils at Reynolds numbers from typical model scale to full scale at Mach numbers from about 0.35 to 0.90. The model scale Reynolds numbers ranged from about 700,00 to 1,500,000 and the full scale Reynolds numbers ranged from about 3,000,000 to 6,600,000. The airfoils tested were the NACA 0012 (0 deg Tab), the SC 1095 R8, and the SC 1095. Both the SC 1095 and the SC 1095 R8 airfoils had trailing edge tabs. The results of this investigation indicate that Reynolds number effects can be significant on the maximum normal force coefficient and all drag related parameters; namely, drag at zero normal force, maximum normal force drag ratio, and drag divergence Mach number. The increments in these parameters at a given Mach number owing to the model scale to full scale Reynolds number change are different for each of the airfoils.
Static Thrust and Power Characteristics of Six Full-Scale Propellers

NASA Technical Reports Server (NTRS)

Hartman, Erwin P; Biermann, David

1940-01-01

Static thrust and power measurements were made of six full-scale propellers. The propellers were mounted in front of a liquid-cooled-engine nacelle and were tested at 15 different blade angles in the range from -7 1/2 degrees to 35 degrees at 0.75r. The test rig was located outdoors and the tests were made under conditions of approximately zero wind velocity.
Tests of a Full-Scale Model of the Republic XF-91 Airplane in the Ames 40- by 80-Foot Wind Tunnel. Force and Moment Data

NASA Technical Reports Server (NTRS)

Hunten, Lynn W.; Dew, Joseph K.

1949-01-01

Wind-tunnel tests of a full-scale model of the Republic XF-91 airplane having swept-back wings and a vee tail were conducted to determine both the stability and control characteristics of the model longitudinally, laterally, and directionally. Configurations of the model were investigated involving such variables as external fuel tanks, a landing gear, trailing-edge flaps, leading-edge slats, and a range of wing incidences and tail incidences.
Entrance to the NACA's Flight Propulsion Research Laboratory

NASA Image and Video Library

1948-08-21

The sign near the entrance of the National Advisory Committee for Aeronautics (NACA) Flight Propulsion Research Laboratory. The name was changed several weeks later to the Lewis Flight Propulsion Laboratory in honor of the NACA’s former Director of Aeronautical Research, George W. Lewis. The research laboratory has had five different names since its inception in 1941. The Cleveland laboratory was originally known as the NACA Aircraft Engine Research Laboratory. In 1947 it was renamed the NACA Flight Propulsion Research Laboratory to reflect the expansion of the research activities beyond just engines. Following the death of George Lewis, the name was changed to the NACA Lewis Flight Propulsion Laboratory in September 1948. On October 1, 1958, the lab was incorporated into the new NASA space agency, and it was renamed the NASA Lewis Research Center. Following John Glenn’s flight on the space shuttle, the name was changed again to the NASA Glenn Research Center on March 1, 1999. From his office in Washington DC, George Lewis managed the aeronautical research conducted at the NACA for over 20 years. His most important accomplishment, however, may have been an investigative tour of German research facilities in the fall of 1936. The visit resulted in the broadening of the scope of the NACA’s research and the physical expansion that included the new engine laboratory in Cleveland.
NACA0012 benchmark model experimental flutter results with unsteady pressure distributions

NASA Technical Reports Server (NTRS)

Rivera, Jose A., Jr.; Dansberry, Bryan E.; Bennett, Robert M.; Durham, Michael H.; Silva, Walter A.

1992-01-01

The Structural Dynamics Division at NASA Langley Research Center has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of this program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type computational fluid dynamics codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. This paper describes results obtained from a second wind tunnel test of the first model in the Benchmark Models Program. This first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree of freedom mount system. Experimental flutter boundaries and corresponding unsteady pressure distribution data acquired over two model chords located at the 60 and 95 percent span stations are presented.
Full-scale fatigue tests of CX-100 wind turbine blades. Part II: analysis

NASA Astrophysics Data System (ADS)

Taylor, Stuart G.; Jeong, Hyomi; Jang, Jae Kyeong; Park, Gyuhae; Farinholt, Kevin M.; Todd, Michael D.; Ammerman, Curtt M.

2012-04-01

This paper presents the initial analysis results of several structural health monitoring (SHM) methods applied to two 9- meter CX-100 wind turbine blades subjected to fatigue loading at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC). The first blade was a pristine blade, manufactured to standard CX-100 design specifications. The second blade was manufactured for the University of Massachusetts, Lowell (UMass), with intentional simulated defects within the fabric layup. Each blade was instrumented with a variety of sensors on its surface. The blades were subject to harmonic excitation at their first natural frequency with steadily increasing loading until ultimately reaching failure. Data from the sensors were collected between and during fatigue loading sessions. The data were measured at multi-scale frequency ranges using a variety of data acquisition equipment, including off-the-shelf systems and prototype data acquisition hardware. The data were analyzed to identify fatigue damage initiation and to assess damage progression. Modal response, diffuse wave-field transfer functions in time and frequency domains, and wave propagation methods were applied to assess the condition of the turbine blade. The analysis methods implemented were evaluated in conjunction with hardware-specific performance for their efficacy in enabling the assessment of damage progression in the blade. The results of this assessment will inform the selection of specific data to be collected and analysis methods to be implemented for a CX-100 flight test to be conducted in collaboration with Sandia National Laboratory at the U.S. Department of Agriculture's (USDA) Conservation and Production Research Laboratory (CPRL) in Bushland, Texas.
The influence of large-scale wind power on global climate.

PubMed

Keith, David W; Decarolis, Joseph F; Denkenberger, David C; Lenschow, Donald H; Malyshev, Sergey L; Pacala, Stephen; Rasch, Philip J

2004-11-16

Large-scale use of wind power can alter local and global climate by extracting kinetic energy and altering turbulent transport in the atmospheric boundary layer. We report climate-model simulations that address the possible climatic impacts of wind power at regional to global scales by using two general circulation models and several parameterizations of the interaction of wind turbines with the boundary layer. We find that very large amounts of wind power can produce nonnegligible climatic change at continental scales. Although large-scale effects are observed, wind power has a negligible effect on global-mean surface temperature, and it would deliver enormous global benefits by reducing emissions of CO(2) and air pollutants. Our results may enable a comparison between the climate impacts due to wind power and the reduction in climatic impacts achieved by the substitution of wind for fossil fuels.
Index of NACA Technical Publications: June, 1955 - June, 1956

NASA Technical Reports Server (NTRS)

1956-01-01

This Index of NACA Technical Publications covers those NACA research reports issued in the period of June 1955 through June 1956. It is the fifth supplement to the basic 1919-1949 Index. The res ear c h reports issued prior to June 1955 which have been declassified since that date have also been included. In addition, current announcement of newly declassified materials is regularly made in the NACA Research Abstracts and Reclassification Notice. The arrangement of the present Index follows that of its predecessors: (1) A listing of the subject categories by numerical classifications, (2) a chronological listing of the NACA research reports under each subject category, (3) an aIphabe ic a I index to the subject categories, and (4) an author index. An Explanatory Chart on page iii may be helpful in identifying references to NACA research reports encountered in the literature. Entries included herein duplicate in part the information of the index cards furnished with the individual research reports. Recipients maintaining card fiIes may wish to discard those index cards on hand for unclassified research reports issued during the June 1955-June 1956 period. Newly available research reports are currently announced in the NACA Research Abstracts and Reclassification Notice and are normally available for a period of five years after announcement. Most of the older research reports (those issued prior to May 1951) are thus available on a "loan only" basis within the United States

Full-scale Wind-tunnel and Flight Tests of a Fairchild 22 Airplane Equipped with External-airfoil Flaps

NASA Technical Reports Server (NTRS)

Reed, Warren D; Clay, William C

1937-01-01

Wind-tunnel and flight tests have been made of a Fairchild 22 airplane equipped with a wing having external-airfoil flaps that also perform the function of ailerons. Lift, drag, and pitching-moment coefficients of the airplane with several flap settings, and the rolling- and yawing-moment coefficients with the flaps deflected as ailerons were measured in the full-scale tunnel with the horizontal tail surfaces and propeller removed. The effect of the flaps on the low speed and on the take-off and landing characteristics, the effectiveness of flaps when used as ailerons, and the forces required to operate them as ailerons were determined in flight. The wind-tunnel tests showed that the flaps increased the maximum lift coefficient of the airplane from 1.51 with the flap in the minimum drag position to 2.12 with the flap in the minimum drag position to 2.12 with the flap deflected 30 degrees. In the flight tests the minimum speed decreased from 46.8 miles per hour with the flaps up to 41.3 miles per hour with the flaps deflected. The required take-off run to attain a height of 50 feet was reduced from 820 to 750 feet and the landing run from a height of 50 feet was reduced from 930 to 480 feet. The flaps for this installation gave lateral control that was not entirely satisfactory. Their rolling action was good but the adverse yaw resulting from their use was greater than is considerable, and the stick forces required to operate them increased too rapidly with speed.
Determination of Scaled Wind Turbine Rotor Characteristics from Three Dimensional RANS Calculations

NASA Astrophysics Data System (ADS)

Burmester, S.; Gueydon, S.; Make, M.

2016-09-01

Previous studies have shown the importance of 3D effects when calculating the performance characteristics of a scaled down turbine rotor [1-4]. In this paper the results of 3D RANS (Reynolds-Averaged Navier-Stokes) computations by Make and Vaz [1] are taken to calculate 2D lift and drag coefficients. These coefficients are assigned to FAST (Blade Element Momentum Theory (BEMT) tool from NREL) as input parameters. Then, the rotor characteristics (power and thrust coefficients) are calculated using BEMT. This coupling of RANS and BEMT was previously applied by other parties and is termed here the RANS-BEMT coupled approach. Here the approach is compared to measurements carried out in a wave basin at MARIN applying Froude scaled wind, and the direct 3D RANS computation. The data of both a model and full scale wind turbine are used for the validation and verification. The flow around a turbine blade at full scale has a more 2D character than the flow properties around a turbine blade at model scale (Make and Vaz [1]). Since BEMT assumes 2D flow behaviour, the results of the RANS-BEMT coupled approach agree better with the results of the CFD (Computational Fluid Dynamics) simulation at full- than at model-scale.
Numerical investigation of the self-starting of a vertical axis wind turbine

NASA Astrophysics Data System (ADS)

Tsai, Hsieh-Chen; Colonius, Tim

2014-11-01

The immersed boundary method is used to simulate the incompressible flow around two-dimensional airfoils at sub-scale Reynolds number in order to investigate the self-starting capability of a vertical-axis wind turbine (VAWT). By investigating a single blade fixed at various angle of attacks, the leading edge vortex (LEV) is shown to play an important role in the starting mechanism for both flat-plate and NACA 0018 blades. Depending on the angle of attack of the blade, as the LEV grows, the corresponding low pressure region results in a thrust in the tangential direction, which produces a positive torque to VAWT. Due to the characteristics of the blades, a NACA 0018 blade produces a larger thrust over a wider range of angle of attacks than a flat-plate blade. Therefore, a VAWT with NACA 0018 blades can self-start more easily than one with flat-plate blades. Moreover, by investigating the starting torque of three-bladed VAWTs fixed at various orientations, the optimal orientation that produces the largest torque to start both VAWTs is with a blade parallel to the flow and facing downstream. The simulations are also compared to results from companion water-tunnel experiments at Caltech. This project is supported by Caltech FLOWE center/Gordon and Betty Moore Foundation.
Hydrodynamic and Aerodynamic Tests of Four Models of Outboard Floats : (N.A.C.A. Models 51-A, 51-B, 51-C, and 51-D)

NASA Technical Reports Server (NTRS)

Dawson, John R; Hartman, Edwin P

1938-01-01

Four models of outboard floats (N.A.C.A. models 51-A, 51-B, 51-C, and 51-D) were tested in the N.A.C.A. tank to determine their hydrodynamic characteristics and in the 20-foot wind tunnel to determine their aerodynamic drag. The results of the tests, together with comparisons of them, are presented in the form of charts. From the comparisons, the order of merit of the models is estimated for each factor considered. The best compromise between the various factors seems to be given by model 51-D. This model is the only one in the series with a transverse step.
Inherent length-scales of periodic solar wind number density structures

NASA Astrophysics Data System (ADS)

Viall, N. M.; Kepko, L.; Spence, H. E.

2008-07-01

We present an analysis of the radial length-scales of periodic solar wind number density structures. We converted 11 years (1995-2005) of solar wind number density data into radial length series segments and Fourier analyzed them to identify all spectral peaks with radial wavelengths between 72 (116) and 900 (900) Mm for slow (fast) wind intervals. Our window length for the spectral analysis was 9072 Mm, approximately equivalent to 7 (4) h of data for the slow (fast) solar wind. We required that spectral peaks pass both an amplitude test and a harmonic F-test at the 95% confidence level simultaneously. From the occurrence distributions of these spectral peaks for slow and fast wind, we find that periodic number density structures occur more often at certain radial length-scales than at others, and are consistently observed within each speed range over most of the 11-year interval. For the slow wind, those length-scales are L ˜ 73, 120, 136, and 180 Mm. For the fast wind, those length-scales are L ˜ 187, 270 and 400 Mm. The results argue for the existence of inherent radial length-scales in the solar wind number density.
Spatial and mineralogic variation of Na-Ca alteration in Laramide porphyry systems of Arizona

NASA Astrophysics Data System (ADS)

Runyon, S.; Seedorff, E.; Barton, M. D.; Mazdab, F. K.; Lecumberri-Sanchez, P.; Steele-MacInnis, M.

2017-12-01

Na-Ca alteration is characterized by the metasomatic addition of Ca ± Na and the loss of K. Minor volumes of Na-Ca alteration in Laramide porphyry systems develops from 3 to 8 km paleodepth. Mineral assemblages, mineral compositions, hydrogen isotopes, whole-rock analyses, and reconnaissance fluid inclusion characteristics have been documented for Na-Ca alteration in Laramide porphyry systems such as Tea Cup and Sierrita. Volumetrically minor Na-Ca alteration in Laramide porphyry systems documented in this study commonly takes the form of one of three mineral assemblages: albite-epidote-chlorite, Na-plagioclase-actinolite ± epidote, and garnet- or diopside-stable Na-plagioclase-actinolite ± epidote. These different Na-Ca mineral assemblages have broad spatial relationships, from shallow albite-chlorite-epidote to deeper Na-plagioclase-actinolite within a given district. Hydrogen isotope data on Na-Ca alteration minerals shows consistently distinct δD compositions of Na-Ca alteration minerals compared to igneous minerals in a given district. Further, calculated hydrogen isotope composition of fluids in equilibrium with Na-Ca alteration minerals are consistently enriched in δD compared to magmatic-hydrothermal fluids. Whole-rock analyses show consistent losses of K and variable addition of Na and Ca across different Na-Ca alteration assemblages. Na-Ca alteration has been well documented associated with the Jurassic arc. Previous studies demonstrated through mass balance, timing and spatial relationships, isotopic, and fluid inclusion studies that Na-Ca alteration associated with the Jurassic arc likely formed from the circulation of external, highly saline, non-magmatic fluids (e.g., Battles and Barton, 1995; Dilles et al., 1995). Na-Ca alteration documented in Laramide systems is generally similar to Na-Ca alteration documented along the Jurassic arc in mineral assemblages, compositions, and timing, but the volume of Na-Ca alteration in the Laramide systems is
Flight and full-scale wind-tunnel comparison of pressure distributions from an F-18 aircraft at high angles of attack. [Conducted in NASA Ames Research Center's 80 by 120 ft wind tunnel

NASA Technical Reports Server (NTRS)

Fisher, David F.; Lanser, Wendy R.

1994-01-01

Pressure distributions were obtained at nearly identical fuselage stations and wing chord butt lines in flight on the F-18 HARV at NASA Dryden Flight Research Center and in the NASA Ames Research Center's 80 by 120 ft wind tunnel on a full-scale F/A-18 aircraft. The static pressures were measured at the identical five stations on the forebody, three stations on the left and right leading-edge extensions, and three spanwise stations on the wing. Comparisons of the flight and wind-tunnel pressure distributions were made at alpha = 30 deg, 45 deg, and 60 deg/59 deg. In general, very good agreement was found. Minor differences were noted at the forebody at alpha = 45 deg and 60 deg in the magnitude of the vortex footprints and a Mach number effect was noted at the leading-edge extension at alpha = 30 deg. The inboard leading edge flap data from the wind tunnel at alpha = 59 deg showed a suction peak that did not appear in the flight data. This was the result of a vortex from the corner of the leading edge flap whose path was altered by the lack of an engine simulation in the wind tunnel.
United States Air Force Academy (USAFA) Vertical Axis Wind Turbine.

DTIC Science & Technology

1980-09-01

Rotors, SAND76-0131. Albuquerque: July 1977. 10. Oliver, R.C. and P.R. Nixon. "Design Procedure for Coupling Savonius and Darrieus Wind Turbines ", Air...May 17-20, 1976. -65- 16. Blackwell, B.F., R.E. Sheldahl, and L.V. Feltz. Wind Tunnel Performance Data for the Darrieus Wind Turbine with NACA 0012...a 5.8 m/s (13 mph) wind . At 100 rpm, the Darrieus turbine would be fully self-sustaining and acceleration would continue to an operating tip speed
Effect of Full-Chord Porosity on Aerodynamic Characteristics of the NACA 0012 Airfoil

NASA Technical Reports Server (NTRS)

Mineck, Raymond E.; Hartwich, Peter M.

1996-01-01

A test was conducted on a model of the NACA 0012 airfoil section with a solid upper surface or a porous upper surface with a cavity beneath for passive venting. The purposes of the test were to investigate the aerodynamic characteristics of an airfoil with full-chord porosity and to assess the ability of porosity to provide a multipoint or self-adaptive design. The tests were conducted in the Langley 8-Foot Transonic Pressure Tunnel over a Mach number range from 0.50 to 0.82 at chord Reynolds numbers of 2 x 10(exp 6), 4 x 10(exp 6), and 6 x 10(exp 6). The angle of attack was varied from -1 deg to 6 deg. At the lower Mach numbers, porosity leads to a dependence of the drag on the normal force. At subcritical conditions, porosity tends to flatten the pressure distribution, which reduces the suction peak near the leading edge and increases the suction over the middle of the chord. At supercritical conditions, the compression region on the porous upper surface is spread over a longer portion of the chord. In all cases, the pressure coefficient in the cavity beneath the porous surface is fairly constant with a very small increase over the rear portion. For the porous upper surface, the trailing edge pressure coefficients exhibit a creep at the lower section normal force coefficients, which suggests that the boundary layer on the rear portion of the airfoil is significantly thickening with increasing normal force coefficient.
A Full Body Steerable Wind Display for a Locomotion Interface.

PubMed

Kulkarni, Sandip D; Fisher, Charles J; Lefler, Price; Desai, Aditya; Chakravarthy, Shanthanu; Pardyjak, Eric R; Minor, Mark A; Hollerbach, John M

2015-10-01

This paper presents the Treadport Active Wind Tunnel (TPAWT)-a full-body immersive virtual environment for the Treadport locomotion interface designed for generating wind on a user from any frontal direction at speeds up to 20 kph. The goal is to simulate the experience of realistic wind while walking in an outdoor virtual environment. A recirculating-type wind tunnel was created around the pre-existing Treadport installation by adding a large fan, ducting, and enclosure walls. Two sheets of air in a non-intrusive design flow along the side screens of the back-projection CAVE-like visual display, where they impinge and mix at the front screen to redirect towards the user in a full-body cross-section. By varying the flow conditions of the air sheets, the direction and speed of wind at the user are controlled. Design challenges to fit the wind tunnel in the pre-existing facility, and to manage turbulence to achieve stable and steerable flow, were overcome. The controller performance for wind speed and direction is demonstrated experimentally.
A restored NACA P-51D Mustang in flight

NASA Image and Video Library

2000-09-15

Bill Allmon of Las Vegas, Nevada, brought his restored NACA P-51D to a reunion of former NACA employees at the NASA Dryden Flight Research Center located at Edwards Air Force Base, Calif., on Sept. 15, 2000. Allmon's award-winning restoration is a genuine former NACA testbed that saw service at the Langley Research Center in Virginia in the late 1940s. Later this Mustang was put on outdoor static display as an Air National Guard monument in Pittsburgh, Pa., where exposure to the elements ravaged its metal structure, necessitating an extensive four-year rebuild.
Interaction Between the Atmospheric Boundary Layer and Wind Energy: From Continental-Scale to Turbine-Scale

NASA Astrophysics Data System (ADS)

St. Martin, Clara Mae

Wind turbines and groups of wind turbines, or "wind plants", interact with the complex and heterogeneous boundary layer of the atmosphere. We define the boundary layer as the portion of the atmosphere directly influenced by the surface, and this layer exhibits variability on a range of temporal and spatial scales. While early developments in wind energy could ignore some of this variability, recent work demonstrates that improved understanding of atmosphere-turbine interactions leads to the discovery of new ways to approach turbine technology development as well as processes such as performance validation and turbine operations. This interaction with the atmosphere occurs at several spatial and temporal scales from continental-scale to turbine-scale. Understanding atmospheric variability over continental-scales and across plants can facilitate reliance on wind energy as a baseload energy source on the electrical grid. On turbine scales, understanding the atmosphere's contribution to the variability in power production can improve the accuracy of power production estimates as we continue to implement more wind energy onto the grid. Wind speed and directional variability within a plant will affect wind turbine wakes within the plants and among neighboring plants, and a deeper knowledge of these variations can help mitigate effects of wakes and possibly even allow the manipulation of these wakes for increased production. Herein, I present the extent of my PhD work, in which I studied outstanding questions at these scales at the intersections of wind energy and atmospheric science. My work consists of four distinct projects. At the coarsest scales, I analyze the separation between wind plant sites needed for statistical independence in order to reduce variability for grid-integration of wind. At lower wind speeds, periods of unstable and more turbulent conditions produce more power than periods of stable and less turbulent conditions, while at wind speeds closer to
Recent "Ground Testing" Experiences in the National Full-Scale Aerodynamics Complex

NASA Technical Reports Server (NTRS)

Zell, Peter; Stich, Phil; Sverdrup, Jacobs; George, M. W. (Technical Monitor)

2002-01-01

The large test sections of the National Full-scale Aerodynamics Complex (NFAC) wind tunnels provide ideal controlled wind environments to test ground-based objects and vehicles. Though this facility was designed and provisioned primarily for aeronautical testing requirements, several experiments have been designed to utilize existing model mount structures to support "non-flying" systems. This presentation will discuss some of the ground-based testing capabilities of the facility and provide examples of groundbased tests conducted in the facility to date. It will also address some future work envisioned and solicit input from the SATA membership on ways to improve the service that NASA makes available to customers.
Rocket Plume Scaling for Orion Wind Tunnel Testing

NASA Technical Reports Server (NTRS)

Brauckmann, Gregory J.; Greathouse, James S.; White, Molly E.

2011-01-01

A wind tunnel test program was undertaken to assess the jet interaction effects caused by the various solid rocket motors used on the Orion Launch Abort Vehicle (LAV). These interactions of the external flowfield and the various rocket plumes can cause localized aerodynamic disturbances yielding significant and highly non-linear control amplifications and attenuations. This paper discusses the scaling methodologies used to model the flight plumes in the wind tunnel using cold air as the simulant gas. Comparisons of predicted flight, predicted wind tunnel, and measured wind tunnel forces-and-moments and plume flowfields are made to assess the effectiveness of the selected scaling methodologies.
40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test Primary Partical Mean Size a (µm) Full Wind Tunnel Test 2 km/hr 24 km/hr Inlet...
40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test Primary Partical Mean Size a (µm) Full Wind Tunnel Test 2 km/hr 24 km/hr Inlet...
40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test Primary Partical Mean Size a (µm) Full Wind Tunnel Test 2 km/hr 24 km/hr Inlet...
40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test...
40 CFR Table F-2 to Subpart F of... - Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test, and Static Chamber Test F Table F-2 to Subpart F... Part 53—Particle Sizes and Wind Speeds for Full Wind Tunnel Test, Wind Tunnel Inlet Aspiration Test...
RSRA sixth scale wind tunnel test. Tabulated balance data, volume 2

NASA Technical Reports Server (NTRS)

Ruddell, A.; Flemming, R.

1974-01-01

Summaries are presented of all the force and moment data acquired during the RSRA Sixth Scale Wind Tunnel Test. These data include and supplement the data presented in curve form in previous reports. Each summary includes the model configuration, wing and empennage incidences and deflections, and recorded balance data. The first group of data in each summary presents the force and moment data in full scale parametric form, the dynamic pressure and velocity in the test section, and the powered nacelle fan speed. The second and third groups of data are the balance data in nondimensional coefficient form. The wind axis coefficient data corresponds to the parametric data divided by the wing area for forces and divided by the product of the wing area and wing span or mean aerodynamic chord for moments. The stability axis data resolves the wind axis data with respect to the angle of yaw.

Preheater in the 10-by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1958-04-21

The 10- by 10-Foot Supersonic Wind Tunnel at the NACA Lewis Flight Propulsion Laboratory was built under the Congressional Unitary Plan Act which coordinated wind tunnel construction at the NACA, Air Force, industry, and universities. The 10- by 10, which began operation in 1956, was the largest of the three NACA tunnels built under the act. Researchers could test engines up to five feet in diameter in the 10- by 10-foot test section. A 250,000-horsepower axial-flow compressor fan can generate airflows up to Mach 3.5 through the test section. The incoming air must be dehumidified and cooled so that the proper conditions are present for the test. A large air dryer with 1,890 tons of activated alumina soaks up 1.5 tons of water per minute from the airflow. A cooling apparatus equivalent to 250,000 household air conditioners is used to cool the air. The air heater is located just upstream from the test section. Natural gas is combusted in the tunnel to increase the air temperature. The system could only be employed when the tunnel was run in its closed-circuit propulsion mode.
Tests of Nacelle-Propeller Combinations in Various Positions with Reference to Wings V : Clark Y Biplane Cellule - NACA Cowled Nacelle - Tractor Propeller

NASA Technical Reports Server (NTRS)

Valentine, E Floyd

1935-01-01

This report is the fifth of a series giving the results obtained from wind tunnel tests on the interference drag and propulsive efficiency of nacelle-propeller-wing combinations. This report gives results of tests of an NACA cowled air-cooled engine nacelle with tractor propeller located in 12 positions with reference to a Clark Y biplane cellule.
Full-scale measurements and system identification on Sutong cable-stayed bridge during Typhoon Fung-Wong.

PubMed

Wang, Hao; Tao, Tianyou; Guo, Tong; Li, Jian; Li, Aiqun

2014-01-01

The structural health monitoring system (SHMS) provides an effective tool to conduct full-scale measurements on existing bridges for essential research on bridge wind engineering. In July 2008, Typhoon Fung-Wong lashed China and hit Sutong cable-stayed bridge (SCB) in China. During typhoon period, full-scale measurements were conducted to record the wind data and the structural vibration responses were collected by the SHMS installed on SCB. Based on the statistical method and the spectral analysis technique, the measured data are analyzed to obtain the typical parameters and characteristics. Furthermore, this paper analyzed the measured structural vibration responses and indicated the vibration characteristics of the stay cable and the deck, the relationship between structural vibrations and wind speed, the comparison of upstream and downstream cable vibrations, the effectiveness of cable dampers, and so forth. Considering the significance of damping ratio in vibration mitigation, the modal damping ratios of the SCB are identified based on the Hilbert-Huang transform (HHT) combined with the random decrement technique (RDT). The analysis results can be used to validate the current dynamic characteristic analysis methods, buffeting calculation methods, and wind tunnel test results of the long-span cable-stayed bridges.
Full-Scale Measurements and System Identification on Sutong Cable-Stayed Bridge during Typhoon Fung-Wong

PubMed Central

Tao, Tianyou; Li, Aiqun

2014-01-01

The structural health monitoring system (SHMS) provides an effective tool to conduct full-scale measurements on existing bridges for essential research on bridge wind engineering. In July 2008, Typhoon Fung-Wong lashed China and hit Sutong cable-stayed bridge (SCB) in China. During typhoon period, full-scale measurements were conducted to record the wind data and the structural vibration responses were collected by the SHMS installed on SCB. Based on the statistical method and the spectral analysis technique, the measured data are analyzed to obtain the typical parameters and characteristics. Furthermore, this paper analyzed the measured structural vibration responses and indicated the vibration characteristics of the stay cable and the deck, the relationship between structural vibrations and wind speed, the comparison of upstream and downstream cable vibrations, the effectiveness of cable dampers, and so forth. Considering the significance of damping ratio in vibration mitigation, the modal damping ratios of the SCB are identified based on the Hilbert-Huang transform (HHT) combined with the random decrement technique (RDT). The analysis results can be used to validate the current dynamic characteristic analysis methods, buffeting calculation methods, and wind tunnel test results of the long-span cable-stayed bridges. PMID:24995367
On the aero-elastic design of the DTU 10MW wind turbine blade for the LIFES50+ wind tunnel scale model

NASA Astrophysics Data System (ADS)

Bayati, I.; Belloli, M.; Bernini, L.; Mikkelsen, R.; Zasso, A.

2016-09-01

This paper illustrates the aero-elastic optimal design, the realization and the verification of the wind tunnel scale model blades for the DTU 10 MW wind turbine model, within LIFES50+ project. The aerodynamic design was focused on the minimization of the difference, in terms of thrust coefficient, with respect to the full scale reference. From the Selig low Reynolds database airfoils, the SD7032 was chosen for this purpose and a proper constant section wing was tested at DTU red wind tunnel, providing force and distributed pressure coefficients for the design, in the Reynolds range 30-250 E3 and for different angles of attack. The aero-elastic design algorithm was set to define the optimal spanwise thickness over chord ratio (t/c), the chord length and the twist to match the first flapwise scaled natural frequency. An aluminium mould for the carbon fibre was CNC manufactured based on B-Splines CAD definition of the external geometry. Then the wind tunnel tests at Politecnico di Milano confirmed successful design and manufacturing approaches.
Exterior of Flexible Wall at the 10- by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1955-03-21

A mechanic checks the tubing on one of the many jacks which control the nozzle section of the 10- by 10-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The 10- by 10-foot tunnel, which had its official opening in May 1956, was built under the Congressional Unitary Plan Act which coordinated wind tunnel construction at the NACA, Air Force, industry, and universities. The 10- by 10 was the largest of the three NACA tunnels built under the act. The 10- by 10 wind tunnel can be operated as a closed circuit for aerodynamic tests or as an open circuit for propulsion investigations. The 10-foot tall and 76-foot long stainless steel nozzle section just upstream from the test section can be adjusted to change the speed and composition of the air flow. Hydraulic jacks, seen in this photograph, flex the 1.37-inch thick walls of the tunnel nozzle. The size of the nozzle’s opening controls the velocity of the air through the test section. Seven General Electric motors capable of generating 25,000 horsepower produce the Mach 2.5 and 2.5 airflows. The facility was mostly operated at night due to its large power load requirements.
Performance Enhancement of a Full-Scale Vertical Tail Model Equipped with Active Flow Control

NASA Technical Reports Server (NTRS)

Whalen, Edward A.; Lacy, Douglas; Lin, John C.; Andino, Marlyn Y.; Washburn, Anthony E.; Graff, Emilio; Wygnanski, Israel J.

2015-01-01

This paper describes wind tunnel test results from a joint NASA/Boeing research effort to advance active flow control (AFC) technology to enhance aerodynamic efficiency. A full-scale Boeing 757 vertical tail model equipped with sweeping jet actuators was tested at the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel (40x80) at NASA Ames Research Center. The model was tested at a nominal airspeed of 100 knots and across rudder deflections and sideslip angles that covered the vertical tail flight envelope. A successful demonstration of AFC-enhanced vertical tail technology was achieved. A 31- actuator configuration significantly increased side force (by greater than 20%) at a maximum rudder deflection of 30deg. The successful demonstration of this application has cleared the way for a flight demonstration on the Boeing 757 ecoDemonstrator in 2015.
Wind Tunnel Measurements of the Wake of a Full-Scale UH-60A Rotor in Forward Flight

NASA Technical Reports Server (NTRS)

Wadcock, Alan J.; Yamauchi, Gloria K.; Schairer, Edward T.

2013-01-01

A full-scale UH-60A rotor was tested in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel in May 2010. The test was designed to acquire a suite of measurements to validate state-of-the-art modeling tools. Measurements include blade airloads (from a single pressure-instrumented blade), blade structural loads (strain gages), rotor performance (rotor balance and torque measurements), blade deformation (stereo-photogrammetry), and rotor wake measurements (Particle Image Velocimetry (PIV) and Retro-reflective Backward Oriented Schlieren (RBOS)). During the test, PIV measurements of flow field velocities were acquired in a stationary cross-flow plane located on the advancing side of the rotor disk at approximately 90 deg rotor azimuth. At each test condition, blade position relative to the measurement plane was varied. The region of interest (ROI) was 4-ft high by 14-ft wide and covered the outer half of the blade radius. Although PIV measurements were acquired in only one plane, much information can be gleaned by studying the rotor wake trajectory in this plane, especially when such measurements are augmented by blade airloads and RBOS data. This paper will provide a comparison between PIV and RBOS measurements of tip vortex position and vortex filament orientation for multiple rotor test conditions. Blade displacement measurements over the complete rotor disk will also be presented documenting blade-to-blade differences in tip-path-plane and providing additional information for correlation with PIV and RBOS measurements of tip vortex location. In addition, PIV measurements of tip vortex core diameter and strength will be presented. Vortex strength will be compared with measurements of maximum bound circulation on the rotor blade determined from pressure distributions obtained from 235 pressure sensors distributed over 9 radial stations.
78 FR 10210 - Utility Scale Wind Towers From China and Vietnam

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-13

...)] Utility Scale Wind Towers From China and Vietnam Determinations On the basis of the record \\1\\ developed... with material injury by reason of imports of utility scale wind towers from China and Vietnam, provided... of imports of utility scale wind towers from China and Vietnam. Commissioner Dean A. Pinkert...
Altitude Wind Tunnel at NASA Glenn Research Center: An Interactive History

NASA Technical Reports Server (NTRS)

2008-01-01

When constructed in the Early 1940s, the Altitude Wind Tunnel (AWT) at NASA Glenn Research Center was the nation's only wind tunnel capable of studying full scale engines under realistic flight conditions. It played a significant role in the development of the first U.S. jet engines as well as technologies such as the afterburner and variable-area nozzle. In the late 1950s, the tunnels interior components were removed so that hardware for Project Mercury could be tested in altitude conditions. In 1961, a portion of the tunnel was converted into one of the country's first large vacuum tanks and renamed the Space Power Chamber (SPC). SPC was used extensively throughout the 1960s for the Centaur rocket program. This multimedia piece allows one to interactively learn about the Altitude Wind Tunnel facility. and the research performed there. The piece contains: (1) A chronological history of the AWT from its construction during World War II and the testing of early jet engines, through the Mercury and Centaur programs of the 1960s and up to the final use of the building for the Microwave Systems laboratory. (2) Photographic surveys of the facility in it wind tunnel, vacuum tank and final configurations. (3) Browsable gallery of over 200 captioned photographs and video clips.(4) A nine minute documentary of the AWT produced by NASA in 1961 (5) Links to over 70 reports and publications related to AWT research and the history of the NACA.
Assessment of C-Type Darrieus Wind Turbine Under Low Wind Speed Condition

NASA Astrophysics Data System (ADS)

Misaran, M. S.; Rahman, Md. M.; Muzammil, W. K.; Ismail, M. A.

2017-07-01

Harvesting wind energy in in a low wind speed region is deem un-economical if not daunting task. Study shows that a minimum cut in speed of 3.5 m/s is required to extract a meaningful wind energy for electricity while a mean speed of 6 m/s is preferred. However, in Malaysia the mean speed is at 2 m/s with certain potential areas having 3 m/s mean speed. Thus, this work aims to develop a wind turbine that able to operate at lower cut-in speed and produce meaningful power for electricity generation. A C-type Darrieus blade is selected as it shows good potential to operate in arbitrary wind speed condition. The wind turbine is designed and fabricated in UMS labs while the performance of the wind turbine is evaluated in a simulated wind condition. Test result shows that the wind turbine started to rotate at 1 m/s compared to a NACA 0012 Darrieus turbine that started to rotate at 3 m/s. The performance of the turbine shows that it have good potential to be used in an intermittent arbitrary wind speed condition as well as low mean wind speed condition.
Wind Tunnel Complex at the Aircraft Engine Research Laboratory

NASA Image and Video Library

1945-09-21

This aerial photograph shows the entire original wind tunnel complex at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory. The large Altitude Wind Tunnel (AWT) at the center of the photograph dominates the area. The Icing Research Tunnel to the right was incorporated into the lab’s design to take advantage of the AWT’s powerful infrastructure. The laboratory’s first supersonic wind tunnel was added to this complex just prior to this September 1945 photograph. The AWT was the nation’s only wind tunnel capable of studying full-scale engines in simulated flight conditions. The AWT’s test section and control room were within the two-story building near the top of the photograph. The exhauster equipment used to thin the airflow and the drive motor for the fan were in the building to the right of the tunnel. The unique refrigeration equipment was housed in the structure to the left of the tunnel. The Icing Research Tunnel was an atmospheric tunnel that used the AWT’s refrigeration equipment to simulate freezing rain inside its test section. A spray bar system inside the tunnel was originally used to create the droplets. The 18- by 18-inch supersonic wind tunnel was built in the summer of 1945 to take advantage of the AWT’s powerful exhaust system. It was the lab’s first supersonic tunnel and could reach Mach 1.91. Eventually the building would house three small supersonic tunnels, referred to as the “stack tunnels” because of the vertical alignment. The two other tunnels were added to this structure in 1949 and 1951.
Index of NACA Technical Publications, July 1956 - June 1957

NASA Technical Reports Server (NTRS)

1957-01-01

This index of NACA Technical Publications covers the NACA research reports issued in the period of July 1956 through June 1957. It is the sixth supplement to the basic 1915-1949 Index. The research reports issued prior to July 1956 which have been declassified since that date have also been included. A list of these reports may be found on pages 243-244. Cards for this list may be discarded as entries for them are included in this Index. Current announcement of newly declassified materials is regularly made in the NACA Research Abstracts and Reclassification Notice. The arrangement of this Index follows: (1) Explanatory chart of NACA publications series designations, (2) outline of subject classification system, (3) chronological list of NACA reports under each subject classification, (4) list of reports declassified from July 1956 through June 1957, (5) alphabetical index to subject categories, and (6) author index. Entries included herein duplicate in part the information of the index cards furnished with the individual research reports. Recipients maintaining card files may wish to discard those index cards on hand for unclassified research reports issued during the July 1956-June 1957 period. Such cards were printed on yellow stock for easy identification in the discard process. Please note that some classified reports issued during the July-December 1956 period are included in the yellow stock area. Therefore care must be taken to avoid destroying such cards. Newly available research reports are currently announced in the NACA Research Abstracts and Reclassification Notice and are normally available for a period of five years after announcement. Most of the older research reports (those issued prior to July 1952) are thus available on a "loan only" basis within the United states.
77 FR 9700 - Utility Scale Wind Towers From China and Vietnam

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-17

...)] Utility Scale Wind Towers From China and Vietnam Determinations On the basis of the record \\1\\ developed... threatened with material injury by reason of imports from China of utility scale wind towers, provided for in... with material injury by reason of imports from Vietnam of utility scale wind towers, provided for in...
Python Turboprop Prepared for a Test in the Altitude Wind Tunnel

NASA Image and Video Library

1949-08-21

A 3670-horsepower Armstrong-Siddeley Python turboprop being prepared for tests in the Altitude Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. In 1947 Lewis researcher Walter Olsen led a group of representatives from the military, industry, and the NACA on a fact finding mission to investigate the technological progress of British turbojet manufacturers. Afterwards several British engines, including the Python, were brought to Cleveland for testing in Lewis’s altitude facilities. The Python was a 14-stage axial-flow compressor turboprop with a fixed-area nozzle and contra-rotating propellers. Early turboprops combined the turbojet and piston engine technologies. They could move large quantities of air so required less engine speed and thus less fuel. This was very appealing to the military for some applications. The military asked the NACA to compare the Python’s performance at sea to that at high altitudes. The NACA researchers studied the Python in the Altitude Wind Tunnel from July 1949 through January 1950. It was the first time the tunnel was used to study an engine with the sole purpose of learning about, not improving it. They analyzed the engine’s dynamic response using a frequency response method at altitudes between 10,000 to 30,000 feet. Lewis researchers found that they could predict the dynamic response characteristics at any altitude from the data obtained from any other specific altitude. This portion of the testing was completed during a single test run.
NACA Pilots at the Aircraft Engine Research Laboratory

NASA Image and Video Library

1945-07-21

The Aircraft Engine Research Laboratory’s pilot corps during the final days of World War II: from left to right, Joseph Vensel, Howard Lilly, William Swann, and Joseph Walker. William “Eb” Gough joined the group months after this photograph. These men were responsible for flying the various National Advisory Committee for Aeronautics (NACA) aircraft to test new engine modifications, study ice buildup, and determine fuel performance. Vensel, a veteran pilot from Langley, was the Chief of Flight Operations and a voice of reason at the laboratory. In April 1947 Vensel was transferred to lead the new Muroc Flight Tests Unit in California until 1966. Lilly was a young pilot with recent Navy experience. Lilly also flew in the 1946 National Air Races. He followed Vensel to Muroc in July 1947 where he became the first NACA pilot to penetrate the sound barrier. On May 3, 1948, Lilly became the first NACA pilot to die in the line of duty. Swann was a young civilian pilot when he joined the NACA. He spent his entire career at the Cleveland laboratory, and led the flight operations group from the early 1960s until 1979. Two World War II veterans joined the crew after the war. Walker was a 24-year-old P–38 reconnaissance pilot. He joined the NACA as a physicist in early 1945 but soon worked his way into the cadre of pilots. Walker later gained fame as an X-plane pilot at Muroc and was killed in a June 1966 fatal crash. Gough survived being shot down twice during the war and was decorated for flying rescue missions in occupied areas.
Aerodynamic Characteristics of a Two-blade NACA 10-(3)(062)-045 Propeller and of a Two-blade NACA 10-(3)(08)-045 Propeller

NASA Technical Reports Server (NTRS)

Solomon, William

1953-01-01

Characteristics are given for the two-blade NACA 10-(3)(062)-045 propeller and for the two-blade NACA 10-(3)(08)-045 propeller over a range of advance ratio from 0.5 to 3.8, through a blade-angle range from 20 degrees to 55 degrees measured at the 0.75 radius. Maximum efficiencies of the order of 91.5 to 92 percent were obtained for the propellers. The propeller with the thinner airfoil sections over the outboard portion of the blades, the NACA 10-(3)(062)-045 propeller, had lower losses at high tip speeds, the difference amounting to about 5 percent at a helical tip Mach number of 1.10.
Ion kinetic scale in the solar wind observed.

PubMed

Śafránková, Jana; Němeček, Zdeněk; Přech, Lubomír; Zastenker, Georgy N

2013-01-11

This Letter shows the first results from the solar wind monitor onboard the Spektr-R spacecraft which measures plasma moments with a time resolution of 31 ms. This high-time resolution allows us to make direct observations of solar wind turbulence below ion kinetic length scales. We present examples of the frequency spectra of the density, velocity, and thermal velocity. Our study reveals that although these parameters exhibit the same behavior at the magnetohydrodynamic scale, their spectra are remarkably different at the kinetic scale.
Research on large-scale wind farm modeling

NASA Astrophysics Data System (ADS)

Ma, Longfei; Zhang, Baoqun; Gong, Cheng; Jiao, Ran; Shi, Rui; Chi, Zhongjun; Ding, Yifeng

2017-01-01

Due to intermittent and adulatory properties of wind energy, when large-scale wind farm connected to the grid, it will have much impact on the power system, which is different from traditional power plants. Therefore it is necessary to establish an effective wind farm model to simulate and analyze the influence wind farms have on the grid as well as the transient characteristics of the wind turbines when the grid is at fault. However we must first establish an effective WTGs model. As the doubly-fed VSCF wind turbine has become the mainstream wind turbine model currently, this article first investigates the research progress of doubly-fed VSCF wind turbine, and then describes the detailed building process of the model. After that investigating the common wind farm modeling methods and pointing out the problems encountered. As WAMS is widely used in the power system, which makes online parameter identification of the wind farm model based on off-output characteristics of wind farm be possible, with a focus on interpretation of the new idea of identification-based modeling of large wind farms, which can be realized by two concrete methods.
Some NACA Muroc personnel with snowman

NASA Technical Reports Server (NTRS)

1949-01-01

The late 1940s saw increased flight activity, and more women computers were needed at the NACA Muroc Flight Test Unit than the ones who had originally arrived in 1946. A call went out to the NACA Langley, Lewis, and Ames laboratories for more women computers. Pictured in this photograph with the Snowman are some of the women computers who responded to the call for help in 1948 along with Roxanah, Emily, Dorothy, who were already here. Standing left to right: Mary (Tut) Hedgepeth, from Langley; Lilly Ann Bajus, Lewis; Roxanah Yancey, Emily Stephens, Jane Collons (Procurement), Leona Corbett (Personnel), Angel Dunn, Langley. Kneeling left to right: Dorothy (Dottie) Crawford Roth, Lewis; Dorothy Clift Hughes, and Gertrude (Trudy) Wilken Valentine, Lewis. In National Advisory Committee for Aeronautics (NACA) terminology of 1946, computers were employees who performed laborious and time-consuming mathematical calculations and data reduction from long strips of records generated by onboard aircraft instrumentation. Virtually without exception, computers were female; at least part of the rationale seems to have been the notion that the work was long and tedious, and men were not thought to have the patience to do it. Though equipment changed over the years and most computers eventually found themselves programming and operating electronic computers, as well as doing other data processing tasks, being a computer initially meant long hours with a slide rule, hunched over illuminated light boxes measuring line traces from grainy and obscure strips of oscillograph film. Computers suffered terrible eyestrain, and those who didn't begin by wearing glasses did so after a few years. But they were initially essential employees at the Muroc Flight Test Unit and NACA High-Speed Flight Research Station, taking the oscillograph flight records and 'reducing' the data on them to make them useful to research engineers, who analyzed the data.

Large-scale wind turbine structures

NASA Technical Reports Server (NTRS)

Spera, David A.

1988-01-01

The purpose of this presentation is to show how structural technology was applied in the design of modern wind turbines, which were recently brought to an advanced stage of development as sources of renewable power. Wind turbine structures present many difficult problems because they are relatively slender and flexible; subject to vibration and aeroelastic instabilities; acted upon by loads which are often nondeterministic; operated continuously with little maintenance in all weather; and dominated by life-cycle cost considerations. Progress in horizontal-axis wind turbines (HAWT) development was paced by progress in the understanding of structural loads, modeling of structural dynamic response, and designing of innovative structural response. During the past 15 years a series of large HAWTs was developed. This has culminated in the recent completion of the world's largest operating wind turbine, the 3.2 MW Mod-5B power plane installed on the island of Oahu, Hawaii. Some of the applications of structures technology to wind turbine will be illustrated by referring to the Mod-5B design. First, a video overview will be presented to provide familiarization with the Mod-5B project and the important components of the wind turbine system. Next, the structural requirements for large-scale wind turbines will be discussed, emphasizing the difficult fatigue-life requirements. Finally, the procedures used to design the structure will be presented, including the use of the fracture mechanics approach for determining allowable fatigue stresses.
Computational Evaluation of Airframe Noise Reduction Concepts at Full Scale

NASA Technical Reports Server (NTRS)

Khorrami, Mehdi R.; Duda, Benjamin; Hazir, Andreas; Fares, Ehab

2016-01-01

High-fidelity simulations focused on full-scale evaluation of new technologies for mitigating flap and landing gear noise are presented. These noise reduction concepts were selected because of their superior acoustic performance, as demonstrated during NASA wind tunnel tests of an 18%-scale, semi-span model of a Gulfstream aircraft. The full-scale, full-aircraft, time-accurate simulations were performed with the lattice Boltzmann PowerFLOW(Registered Trademark) solver for free air at a Mach number of 0.2. Three aircraft configurations (flaps deflected at 39? without and with main gear deployed, and 0? flaps with main gear extended) were used to determine the aero-acoustic performance of the concepts on component-level (individually) and system-level (concurrent applica-tion) bases. Farfield noise spectra were obtained using a Ffowcs-Williams and Hawkings acoustic analogy approach. Comparison of the predicted spectra without (baseline) and with the noise treatments applied showed that noise reduction benefits between 2-3 dB for the flap and 1.3-1.7 dB for the main landing gear are obtained. It was also found that the full extent of the benefits is being masked by the noise generated from the flap brackets and main gear cavities, which act as prominent secondary sources.
Computational examination of utility scale wind turbine wake interactions

DOE PAGES

Okosun, Tyamo; Zhou, Chenn Q.

2015-07-14

We performed numerical simulations of small, utility scale wind turbine groupings to determine how wakes generated by upstream turbines affect the performance of the small turbine group as a whole. Specifically, various wind turbine arrangements were simulated to better understand how turbine location influences small group wake interactions. The minimization of power losses due to wake interactions certainly plays a significant role in the optimization of wind farms. Since wind turbines extract kinetic energy from the wind, the air passing through a wind turbine decreases in velocity, and turbines downstream of the initial turbine experience flows of lower energy, resultingmore » in reduced power output. Our study proposes two arrangements of turbines that could generate more power by exploiting the momentum of the wind to increase velocity at downstream turbines, while maintaining low wake interactions at the same time. Furthermore, simulations using Computational Fluid Dynamics are used to obtain results much more quickly than methods requiring wind tunnel models or a large scale experimental test.« less
NACA Computers Take Readings From Manometer Boards

NASA Image and Video Library

1949-02-21

Female computers at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory copy pressure readings from rows of manometers below the 18- by 18-inch Supersonic Wind Tunnel. The computers obtained test data from the manometers and other instruments, made the initial computations, and plotted the information graphically. Based on these computations, the researchers planned their next test or summarized their findings in a report. Manometers were mercury-filled glass tubes that were used to indicate different pressure levels from inside the test facility or from the test article. Manometers look and function very similarly to thermometers. Dozens of pressure sensing instruments were installed for each test. Each was connected to a manometer tube located inside the control room. The mercury inside the manometer rose and fell with the pressure levels. The dark mercury can be seen in this photograph at different levels within the tubes. Since this activity was dynamic, it was necessary to note the levels at given points during the test. This was done using both computer notations and photography.
0.4 Percent Scale Space Launch System Wind Tunnel Test

NASA Image and Video Library

2011-11-15

0.4 Percent Scale Space Launch System Wind Tunnel Test 0.4 Percent Scale SLS model installed in the NASA Langley Research Center Unitary Plan Wind Tunnel Test Section 1 for aerodynamic force and movement testing.
Contribution of large scale coherence to wind turbine power: A large eddy simulation study in periodic wind farms

NASA Astrophysics Data System (ADS)

Chatterjee, Tanmoy; Peet, Yulia T.

2018-03-01

Length scales of eddies involved in the power generation of infinite wind farms are studied by analyzing the spectra of the turbulent flux of mean kinetic energy (MKE) from large eddy simulations (LES). Large-scale structures with an order of magnitude bigger than the turbine rotor diameter (D ) are shown to have substantial contribution to wind power. Varying dynamics in the intermediate scales (D -10 D ) are also observed from a parametric study involving interturbine distances and hub height of the turbines. Further insight about the eddies responsible for the power generation have been provided from the scaling analysis of two-dimensional premultiplied spectra of MKE flux. The LES code is developed in a high Reynolds number near-wall modeling framework, using an open-source spectral element code Nek5000, and the wind turbines have been modelled using a state-of-the-art actuator line model. The LES of infinite wind farms have been validated against the statistical results from the previous literature. The study is expected to improve our understanding of the complex multiscale dynamics in the domain of large wind farms and identify the length scales that contribute to the power. This information can be useful for design of wind farm layout and turbine placement that take advantage of the large-scale structures contributing to wind turbine power.
Analysis of the Na+/Ca2+ Exchanger Gene Family within the Phylum Nematoda

PubMed Central

He, Chao; O'Halloran, Damien M.

2014-01-01

Na+/Ca2+ exchangers are low affinity, high capacity transporters that rapidly transport calcium at the plasma membrane, mitochondrion, endoplasmic (and sarcoplasmic) reticulum, and the nucleus. Na+/Ca2+ exchangers are widely expressed in diverse cell types where they contribute homeostatic balance to calcium levels. In animals, Na+/Ca2+ exchangers are divided into three groups based upon stoichiometry: Na+/Ca2+ exchangers (NCX), Na+/Ca2+/K+ exchangers (NCKX), and Ca2+/Cation exchangers (CCX). In mammals there are three NCX genes, five NCKX genes and one CCX (NCLX) gene. The genome of the nematode Caenorhabditis elegans contains ten Na+/Ca2+ exchanger genes: three NCX; five CCX; and two NCKX genes. Here we set out to characterize structural and taxonomic specializations within the family of Na+/Ca2+ exchangers across the phylum Nematoda. In this analysis we identify Na+/Ca2+ exchanger genes from twelve species of nematodes and reconstruct their phylogenetic and evolutionary relationships. The most notable feature of the resulting phylogenies was the heterogeneous evolution observed within exchanger subtypes. Specifically, in the case of the CCX exchangers we did not detect members of this class in three Clade III nematodes. Within the Caenorhabditis and Pristionchus lineages we identify between three and five CCX representatives, whereas in other Clade V and also Clade IV nematode taxa we only observed a single CCX gene in each species, and in the Clade III nematode taxa that we sampled we identify NCX and NCKX encoding genes but no evidence of CCX representatives using our mining approach. We also provided re-annotation for predicted CCX gene structures from Heterorhabditis bacteriophora and Caenorhabditis japonica by RT-PCR and sequencing. Together, these findings reveal a complex picture of Na+/Ca2+ transporters in nematodes that suggest an incongruent evolutionary history of proteins that provide central control of calcium dynamics. PMID:25397810
A Comparison of the Results from General Tank Tests of 1/6- and 1/12-full-size Models of the British Singapore IIC Flying Boat

NASA Technical Reports Server (NTRS)

Truscott, Starr; Dawson, John R

1942-01-01

A 1/6-full-size model of the hull of the British Singapore IIC flying boat was tested in the NACA tank. The results are given in the form of charts and are compared with the results of previous tests made in the NACA tank of a 1/12-full-size model, published in NACA T.N. No. 580, and with the results of tests made in the British R.A.E. tank of another 1/6-full-size model of the same hull. When the data from the tests of the 1/6- and 1/12-full-size models were compared on the basis of Froude's law of comparison, differences were found. This fact supported the belief that the small scale of the model and the use of a model that was too small to suit the equipment of the NACA tank had caused the results of the tests of the 1/12-full-size model to be less reliable than the results of the tests of the 1/6-full-size model. The results of the tests of the two models agreed sufficiently well to show that test of a small model, if made meticulously and with suitable equipment, may give useable results, but that a larger model should be used whenever feasible. The results of the NACA tests of the 1/6-full-size model were found to be in good agreement with the R.A.E. tests of a model of the same size.
Vertical Descent and Landing Tests of a 0.13-Scale Model of the Convair XFY-1 Vertically Rising Airplane in Still Air, TED No. NACA DE 368

NASA Technical Reports Server (NTRS)

Smith, Charlee C., Jr.; Lovell, Powell M., Jr.

1954-01-01

An investigation is being conducted to determine the dynamic stability and control characteristics of a 0.13-scale flying model of Convair XFY-1 vertically rising airplane. This paper presents the results of flight and force tests to determine the stability and control characteristics of the model in vertical descent and landings in still air. The tests indicated that landings, including vertical descent from altitudes representing up to 400 feet for the full-scale airplane and at rates of descent up to 15 or 20 feet per second (full scale), can be performed satisfactorily. Sustained vertical descent in still air probably will be more difficult to perform because of large random trim changes that become greater as the descent velocity is increased. A slight steady head wind or cross wind might be sufficient to eliminate the random trim changes.
Full scale visualization of the wing tip vortices generated by a typical agricultural aircraft

NASA Technical Reports Server (NTRS)

Cross, E. J., Jr.; Bridges, P.; Brownlee, J. A.; Liningston, W. W.

1980-01-01

The trajectories of the wing tip vortices of a typical agricultural aircraft were experimentally determined by flight test. A flow visualization method, similar to the vapor screen method used in wind tunnels, was used to obtain trajectory data for a range of flight speeds, airplane configurations, and wing loadings. Detailed measurements of the spanwise surface pressure distribution were made for all test points. Further, a powered 1/8 scale model of the aircraft was designed, built, and used to obtain tip vortex trajectory data under conditions similar to that of the full-scale test. The effects of light wind on the vortices were demonstrated, and the interaction of the flap vortex and the tip vortex was clearly shown in photographs and plotted trajectory data.
Simulating flow around scaled model of a hypersonic vehicle in wind tunnel

NASA Astrophysics Data System (ADS)

Markova, T. V.; Aksenov, A. A.; Zhluktov, S. V.; Savitsky, D. V.; Gavrilov, A. D.; Son, E. E.; Prokhorov, A. N.

2016-11-01

A prospective hypersonic HEXAFLY aircraft is considered in the given paper. In order to obtain the aerodynamic characteristics of a new construction design of the aircraft, experiments with a scaled model have been carried out in a wind tunnel under different conditions. The runs have been performed at different angles of attack with and without hydrogen combustion in the scaled propulsion engine. However, the measured physical quantities do not provide all the information about the flowfield. Numerical simulation can complete the experimental data as well as to reduce the number of wind tunnel experiments. Besides that, reliable CFD software can be used for calculations of the aerodynamic characteristics for any possible design of the full-scale aircraft under different operation conditions. The reliability of the numerical predictions must be confirmed in verification study of the software. The given work is aimed at numerical investigation of the flowfield around and inside the scaled model of the HEXAFLY-CIAM module under wind tunnel conditions. A cold run (without combustion) was selected for this study. The calculations are performed in the FlowVision CFD software. The flow characteristics are compared against the available experimental data. The carried out verification study confirms the capability of the FlowVision CFD software to calculate the flows discussed.
Probing wind-turbine/atmosphere interactions at utility scale: Novel insights from the EOLOS wind energy research station

NASA Astrophysics Data System (ADS)

Hong, J.; Guala, M.; Chamorro, L. P.; Sotiropoulos, F.

2014-06-01

Despite major research efforts, the interaction of the atmospheric boundary layer with turbines and multi-turbine arrays at utility scale remains poorly understood today. This lack of knowledge stems from the limited number of utility-scale research facilities and a number of technical challenges associated with obtaining high-resolution measurements at field scale. We review recent results obtained at the University of Minnesota utility-scale wind energy research station (the EOLOS facility), which is comprised of a 130 m tall meteorological tower and a fully instrumented 2.5MW Clipper Liberty C96 wind turbine. The results address three major areas: 1) The detailed characterization of the wake structures at a scale of 36×36 m2 using a novel super-large-scale particle image velocimetry based on natural snowflakes, including the rich tip vortex dynamics and their correlation with turbine operations, control, and performance; 2) The use of a WindCube Lidar profiler to investigate how wind at various elevations influences turbine power fluctuation and elucidate the role of wind gusts on individual blade loading; and 3) The systematic quantification of the interaction between the turbine instantaneous power output and tower foundation strain with the incoming flow turbulence, which is measured from the meteorological tower.
Evaluation of a micro-scale wind model's performance over realistic building clusters using wind tunnel experiments

NASA Astrophysics Data System (ADS)

Zhang, Ning; Du, Yunsong; Miao, Shiguang; Fang, Xiaoyi

2016-08-01

The simulation performance over complex building clusters of a wind simulation model (Wind Information Field Fast Analysis model, WIFFA) in a micro-scale air pollutant dispersion model system (Urban Microscale Air Pollution dispersion Simulation model, UMAPS) is evaluated using various wind tunnel experimental data including the CEDVAL (Compilation of Experimental Data for Validation of Micro-Scale Dispersion Models) wind tunnel experiment data and the NJU-FZ experiment data (Nanjing University-Fang Zhuang neighborhood wind tunnel experiment data). The results show that the wind model can reproduce the vortexes triggered by urban buildings well, and the flow patterns in urban street canyons and building clusters can also be represented. Due to the complex shapes of buildings and their distributions, the simulation deviations/discrepancies from the measurements are usually caused by the simplification of the building shapes and the determination of the key zone sizes. The computational efficiencies of different cases are also discussed in this paper. The model has a high computational efficiency compared to traditional numerical models that solve the Navier-Stokes equations, and can produce very high-resolution (1-5 m) wind fields of a complex neighborhood scale urban building canopy (~ 1 km ×1 km) in less than 3 min when run on a personal computer.
An Investigation of the Low-speed Stability and Control Characteristics of Swept-forward and Swept-back Wing in the Ames 40- by 80-foot Wind Tunnel

NASA Technical Reports Server (NTRS)

Mccormack, Gerald M; Stevens, Victor I , Jr

1947-01-01

An investigation has been made at large scale of the characteristics of highly swept wings. Data were obtained at several angles of sideslip on wings having angles of sweep of plus or minus 45 degrees, plus or minus 30 degrees, and 0 degrees. The airfoil sections of the wings varied from approximately NACA 0015 at the root to NACA 23009 at the tip. Each wing was investigated with flaps under flection, partial-span split flaps deflected 60 degrees, full-span split flaps defected 60 degrees and split-flap-type ailerons deflected plus or minus 15 degrees. Values of maximum lift were obtained at Reynolds numbers raging from 5.7 to 9.2 times 10 to the 6th power. In this report the summarized results are compared with the predictions made by use of the simplified theory for the effect of sweep and with existing small-scale data. The basic wind-tunnel results from which these summary data were taken are included in an appendix. The primary problems accompanying the use of weep as revealed by this investigation are the loss in maximum lift, the high effective dihedral, and the sharp reduction in lateral-control effectiveness. In general, simple theory enables good predictions to be made of the gross effects of sweep but further refinements are necessary to obtain the accuracy required for design purposes. In cases where comparisons can be made, the indications are that, as sweep increases, scale effects diminish and large-scale results approach small-scale results.
Wind-tunnel investigation of a full-scale canard-configured general aviation aircraft

NASA Technical Reports Server (NTRS)

Yip, L. P.; Coy, P. F.

1982-01-01

As part of a broad research program to provide a data base on advanced airplane configurations, a wind-tunnel investigation was conducted in the Langley 30-by 60-Foot Wind Tunnel to determine the aerodynamic characteristics of an advanced canard-configured general aviation airplane. The investigation included measurements of forces and moments of the complete configuration, isolated canard loads, and pressure distributions on the wing, winglet, and canard. Flow visualization was obtained by using surface tufts to determine regions of flow separation and by using a chemical sublimation technique to determine boundary-layer transition locations. Additionally, other tests were conducted to determine simulated rain effects on boundary layer transition. Investigation of configuration effects included variations of canard locations, canard airfoil section, winglet size, and use of a leading-edge droop on the out-board section of the wing.
Development and Validation of a Rating Scale for Wind Jazz Improvisation Performance

ERIC Educational Resources Information Center

Smith, Derek T.

2009-01-01

The purpose of this study was to construct and validate a rating scale for collegiate wind jazz improvisation performance. The 14-item Wind Jazz Improvisation Evaluation Scale (WJIES) was constructed and refined through a facet-rational approach to scale development. Five wind jazz students and one professional jazz educator were asked to record…
Experimental flutter boundaries with unsteady pressure distributions for the NACA 0012 Benchmark Model

NASA Technical Reports Server (NTRS)

Rivera, Jose A., Jr.; Dansberry, Bryan E.; Farmer, Moses G.; Eckstrom, Clinton V.; Seidel, David A.; Bennett, Robert M.

1991-01-01

The Structural Dynamics Div. at NASA-Langley has started a wind tunnel activity referred to as the Benchmark Models Program. The objective is to acquire test data that will be useful for developing and evaluating aeroelastic type Computational Fluid Dynamics codes currently in use or under development. The progress is described which was achieved in testing the first model in the Benchmark Models Program. Experimental flutter boundaries are presented for a rigid semispan model (NACA 0012 airfoil section) mounted on a flexible mount system. Also, steady and unsteady pressure measurements taken at the flutter condition are presented. The pressure data were acquired over the entire model chord located at the 60 pct. span station.
Potential climatic impacts and reliability of large-scale offshore wind farms

NASA Astrophysics Data System (ADS)

Wang, Chien; Prinn, Ronald G.

2011-04-01

The vast availability of wind power has fueled substantial interest in this renewable energy source as a potential near-zero greenhouse gas emission technology for meeting future world energy needs while addressing the climate change issue. However, in order to provide even a fraction of the estimated future energy needs, a large-scale deployment of wind turbines (several million) is required. The consequent environmental impacts, and the inherent reliability of such a large-scale usage of intermittent wind power would have to be carefully assessed, in addition to the need to lower the high current unit wind power costs. Our previous study (Wang and Prinn 2010 Atmos. Chem. Phys. 10 2053) using a three-dimensional climate model suggested that a large deployment of wind turbines over land to meet about 10% of predicted world energy needs in 2100 could lead to a significant temperature increase in the lower atmosphere over the installed regions. A global-scale perturbation to the general circulation patterns as well as to the cloud and precipitation distribution was also predicted. In the later study reported here, we conducted a set of six additional model simulations using an improved climate model to further address the potential environmental and intermittency issues of large-scale deployment of offshore wind turbines for differing installation areas and spatial densities. In contrast to the previous land installation results, the offshore wind turbine installations are found to cause a surface cooling over the installed offshore regions. This cooling is due principally to the enhanced latent heat flux from the sea surface to lower atmosphere, driven by an increase in turbulent mixing caused by the wind turbines which was not entirely offset by the concurrent reduction of mean wind kinetic energy. We found that the perturbation of the large-scale deployment of offshore wind turbines to the global climate is relatively small compared to the case of land
Altitude Wind Tunnel Control Room at the Aircraft Engine Research Laboratory

NASA Image and Video Library

1944-07-21

Operators in the control room for the Altitude Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory remotely operate a Wright R–3350 engine in the tunnel’s test section. Four of the engines were used to power the B–29 Superfortress, a critical weapon in the Pacific theater during World War II. The wind tunnel, which had been in operation for approximately six months, was the nation’s only wind tunnel capable of testing full-scale engines in simulated altitude conditions. The soundproof control room was used to operate the wind tunnel and control the engine being run in the test section. The operators worked with assistants in the adjacent Exhauster Building and Refrigeration Building to manage the large altitude simulation systems. The operator at the center console controlled the tunnel’s drive fan and operated the engine in the test section. Two sets of pneumatic levers near his right forearm controlled engine fuel flow, speed, and cooling. Panels on the opposite wall, out of view to the left, were used to manage the combustion air, refrigeration, and exhauster systems. The control panel also displayed the master air speed, altitude, and temperature gauges, as well as a plethora of pressure, temperature, and airflow readings from different locations on the engine. The operator to the right monitored the manometer tubes to determine the pressure levels. Despite just being a few feet away from the roaring engine, the control room remained quiet during the tests.
NACA Computer Operates an IBM Telereader

NASA Image and Video Library

1952-02-21

A staff member from the Computing Section at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory operates an International Business Machines (IBM) telereader at the 8- by 6-Foot Supersonic Wind Tunnel. The telereader was used to measure recorded data from motion picture film or oscillographs. The machine could perform 50 measurements per minute. The component to her right is a telerecordex that was used convert the telereader measurements into decimal form and record the data on computer punch cards. During test runs in the 8- by 6-foot tunnel, or the other large test facilities, pressure sensors on the test article were connected to mercury-filled manometer tubes located below the test section. The mercury would rise or fall in relation to the pressure fluctuations in the test section. Initially, female staff members, known as “computers,” transcribed all the measurements by hand. The process became automated with the introduction of the telereader and other data reduction equipment in the early 1950s. The Computer Section staff members were still needed to operate the machines. The Computing Section was introduced during World War II to relieve short-handed research engineers of some of the tedious work. The computers made the initial computations and plotted the data graphically. The researcher then analyzed the data and either summarized the findings in a report or made modifications or ran the test again. The computers and analysts were located in the Altitude Wind Tunnel Shop and Office Building office wing during the 1940s. They were transferred to the new facility when the 8- by 6-Foot tunnel began operations in 1948.

Na/Ca Ratio in Large Benthic Foraminifera as a Novel Proxy for Past Ocean Calcium

NASA Astrophysics Data System (ADS)

Rosenthal, Y.; Hauzer, H.; Evans, D.; Erez, J.

2017-12-01

Culture experiments with Operculina ammonoides (a large symbiont bearing benthic foraminifer and an extant relative of the Eocene Nummulites) were carried out varying seawater [Ca], temperature and salinity. The main results of these experiments are: 1. Na/Ca in these foraminifera shells varies with the Na/Ca ratio in the seawater 2. Na/Ca shows small, non-systematic variations with temperature (22-28 ºC) that are within our analytical precision. 3. Na/Ca in the shells show very low changes, increasing linearly with salinity. The sensitivity to salinity is very low compared to that caused by changes of Na/Ca in seawater. Over the seawater experimental range of Na/Ca (10-18 mM), a change of 5 ppt salinity induced a slight Na/Ca increase comparable to the analytical error for Na, or that caused by temperature. Initial reconstructions of seawater [Ca], based on these calibrations, generally agree well with previous models and reconstructions confirming that seawater [Ca] concentrations were substantially higher during the early-mid Cenozoic than today.
Large-Scale Wind Turbine Testing in the NASA 24.4m (80) by 36.6m(120) Wind Tunnel

NASA Technical Reports Server (NTRS)

Zell, Peter T.; Imprexia, Cliff (Technical Monitor)

2000-01-01

The 80- by 120-Foot Wind Tunnel at NASA Ames Research Center in California provides a unique capability to test large-scale wind turbines under controlled conditions. This special capability is now available for domestic and foreign entities wishing to test large-scale wind turbines. The presentation will focus on facility capabilities to perform wind turbine tests and typical research objectives for this type of testing.
Internal Acoustics Measurements of a Full Scale Advanced Ducted Propulsor Demonstrator

NASA Technical Reports Server (NTRS)

Santa Maria, O. L.; Soderman, P. T.; Horne, W. C.; Jones, M. G.; Bock, L. A.

1995-01-01

Acoustics measurements of a Pratt & Whitney full-scale ADP (Advanced Ducted Propulsor), an ultrahigh by-pass ratio engine, were conducted in the NASA Ames 40- by 80-Foot Wind Tunnel. This paper presents data from measurements taken from sensors on a fan exit guide vane in the ADP. Data from two sensors, one at mid-span and the other at the tip of the fan exit guide vane, are presented. At the blade passage frequency (BPF), the levels observed at the various engine and wind speeds were higher at the mid-span sensor than the tip sensor. The coherence between these internal sensors and external microphones were calculated and plotted as a function of angle (angles ranged from 5 degrees to 160 degrees) relative to the ADP longitudinal axis. At the highest engine and wind speeds, the coherence between the tip sensor and the external microphones was observed to decrease at higher multiples of the BPF. These results suggest that the rotor-stator interaction tones are stronger in the mid-span region than at the tip.
NACA Conference on Aircraft Loads, Flutter, and Structures: A compilation of Papers Presented.

DTIC Science & Technology

1953-03-04

Variation of Atmospheric Turbulence With Altitude and Its Effect on Airplane Gust Loads . . . by Robert L. McDougal, Thomas L. Coleman, and Philip L. Smith ...SKOPINSKI, T. H. NACA - Langley Laboratory xvii CONFIDENTIAL CONFIDENTIAL SMETHERS, Rollo G. Bureau of Aeronautics SMITH , Dana W. NACA Subcommittee on...Aircraft Structural Materials SMITH , Frank C. National Bureau of Standards SMITH , Henry G. Hughes Aircraft Co. SMITH , Howard W. NACA Subcommittee on Aircraft
Refrigeration Compressors for the Altitude Wind Tunnel

NASA Image and Video Library

1944-09-21

These compressors inside the Refrigeration Building at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory were used to generate cold temperatures in the Altitude Wind Tunnel (AWT) and Icing Research Tunnel. The AWT was a large facility that simulated actual flight conditions at high altitudes. The two primary aspects of altitude simulation are the reduction of the air pressure and the decrease of temperature. The Icing Research Tunnel was a smaller facility in which water droplets were added to the refrigerated air stream to simulate weather conditions that produced ice buildup on aircraft. The military pressured the NACA to complete the tunnels quickly so they could be of use during World War II. The NACA engineers struggled with the design of this refrigeration system, so Willis Carrier, whose Carrier Corporation had pioneered modern refrigeration, took on the project. The Carrier engineers devised the largest cooling system of its kind in the world. The system could lower the tunnels’ air temperature to –47⁰ F. The cooling system was powered by 14 Carrier and York compressors, seen in this photograph, which were housed in the Refrigeration Building between the two wind tunnels. The compressors converted the Freon 12 refrigerant into a liquid. The refrigerant was then pumped into zig-zag banks of cooling coils inside the tunnels’ return leg. The Freon absorbed heat from the airflow as it passed through the coils. The heat was transferred to the cooling water and sent to the cooling tower where it was dissipated into the atmosphere.
REGIONAL-SCALE WIND FIELD CLASSIFICATION EMPLOYING CLUSTER ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glascoe, L G; Glaser, R E; Chin, H S

2004-06-17

The classification of time-varying multivariate regional-scale wind fields at a specific location can assist event planning as well as consequence and risk analysis. Further, wind field classification involves data transformation and inference techniques that effectively characterize stochastic wind field variation. Such a classification scheme is potentially useful for addressing overall atmospheric transport uncertainty and meteorological parameter sensitivity issues. Different methods to classify wind fields over a location include the principal component analysis of wind data (e.g., Hardy and Walton, 1978) and the use of cluster analysis for wind data (e.g., Green et al., 1992; Kaufmann and Weber, 1996). The goalmore » of this study is to use a clustering method to classify the winds of a gridded data set, i.e, from meteorological simulations generated by a forecast model.« less
National-Scale Wind Resource Assessment for Power Generation (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baring-Gould, E. I.

2013-08-01

This presentation describes the current standards for conducting a national-scale wind resource assessment for power generation, along with the risk/benefit considerations to be considered when beginning a wind resource assessment. The presentation describes changes in turbine technology and viable wind deployment due to more modern turbine technology and taller towers and shows how the Philippines national wind resource assessment evolved over time to reflect changes that arise from updated technologies and taller towers.
Nature of Kinetic Scale Fluctuations in Solar Wind Turbulence

NASA Astrophysics Data System (ADS)

Salem, C. S.; Chen, C. H.; Sundkvist, D. J.; Chaston, C. C.; Bale, S. D.; Mozer, F.

2012-12-01

We present an investigation of the nature of small-scale turbulent fluctuations in the solar wind. The nature of the dissipation range fluctuations of solar wind turbulence remains a major open question in heliospheric physics. The steepening of the observed (magnetic field) spectra at ion scales was originally attributed to ion cyclotron damping, but it was later suggested that it could well be due to the dispersive nature of fluctuations at these scales. The nature of the dispersive cascade at and below the ion scales is still debated, two leading hypothesis being that these fluctuations have characteristics of Kinetic Alfven Waves (KAW) or whistler waves. Other possible contributions from current sheets and/or kinetic instabilities have been suggested. There is mounting evidence that the fluctuations at these scales are KAW-like. In this study, we analyze several carefully selected unperturbed solar wind intervals, using magnetic field, electric field as well as density measurements from the Cluster spacecraft in order to identify the nature of the wave modes present, how frequent they are and try to determine whether one or more wave modes at different times. We examine the electric to magnetic field fluctuation ratio (δ E/δd B), the magnetic compressibility (δ B∥ /δ B) as well as density fluctuations using newly developed diagnostic techniques by Salem et al (2012) and Chen et al (2012). We look for variations of the nature and properties of these kinetic scale fluctuations with solar wind conditions, such as the plasma beta and the angle between the magnetic field and the flow velocity which controls the measured (spacecraft frame) frequency of the fluctuations. We discuss how these results would impact how the solar wind plasma is heated.
Intermittency of solar wind on scale 0.01-16 Hz.

NASA Astrophysics Data System (ADS)

Riazantseva, Maria; Zastenker, Georgy; Chernyshov, Alexander; Petrosyan, Arakel

Magnetosphere of the Earth is formed in the process of solar wind flow around earth's magnetic field. Solar wind is a flow of turbulent plasma that displays a multifractal structure and an intermittent character. That is why the study of the characteristics of solar wind turbulence is very important part of the solution of the problem of the energy transport from the solar wind to magnetosphere. A large degree of intermittency is observed in the solar wind ion flux and magnetic field time rows. We investigated the intermittency of solar wind fluctuations under large statistics of high time resolution measurements onboard Interball-1 spacecraft on scale from 0.01 to 16 Hz. Especially it is important that these investigation is carry out for the first time for the earlier unexplored (by plasma data) region of comparatively fast variations (frequency up to 16 Hz), so we significantly extend the range of intermittency observations for solar wind plasma. The intermittency practically absent on scale more then 1000 s and it grows to the small scales right up till t 30-60 s. The behavior of the intermittency for the scale less then 30-60 s is rather changeable. The boundary between these two rates of intermittency is quantitatively near to the well-known boundary between the dissipation and inertial scales of fluctuations, what may point to their possible relation. Special attention is given to a comparison of intermittency for solar wind observation intervals containing SCIF (Sudden Changes of Ion Flux) to ones for intervals without SCIF. Such a comparison allows one to reveal the fundamental turbulent properties of the solar wind regions in which SCIF is observed more frequently. We use nearly incompressible model of the solar wind turbulence for obtained data interpretation. The regime when density fluctuations are passive scalar in a hydrodynamic field of velocity is realized in turbulent solar wind flows according to this model. This hypothesis can be verified
Full-Sun observations for identifying the source of the slow solar wind

PubMed Central

Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P.

2015-01-01

Fast (>700 km s−1) and slow (~400 km s−1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. PMID:25562705
NACA 0015 wing pressure and trailing vortex measurements

NASA Technical Reports Server (NTRS)

Mcalister, K. W.; Takahashi, R. K.

1991-01-01

A NACA 0015 semispan wing was placed in a low-speed wind tunnel, and measurements were made of the pressure on the upper and lower surface of the wing and of velocity across the vortex trailing downstream from the tip of the wing. Pressure data were obtained for both 2-D and 3-D configurations. These data feature a detailed comparison between wing tips with square and round lateral edges. A two-component laser velocimeter was used to measure velocity profiles across the vortex at numerous stations behind the wing and for various combinations of conditions. These conditions include three aspect ratios, three chord lengths, a square- and a round lateral-tip, presence or absence of a boundary-layer trip, and three image plane positions located opposite the wing tip. Both pressure and velocity measurements were made for the angles of attack 4 deg less than or equal to alpha less than or equal to 12 deg and for Reynolds numbers 1 x 10(exp 6) less than or equal to Re less than or equal to 3 x 10(exp 6).
LPV Control for the Full Region Operation of a Wind Turbine Integrated with Synchronous Generator

PubMed Central

Grigoriadis, Karolos M.; Nyanteh, Yaw D.

2015-01-01

Wind turbine conversion systems require feedback control to achieve reliable wind turbine operation and stable current supply. A robust linear parameter varying (LPV) controller is proposed to reduce the structural loads and improve the power extraction of a horizontal axis wind turbine operating in both the partial load and the full load regions. The LPV model is derived from the wind turbine state space models extracted by FAST (fatigue, aerodynamics, structural, and turbulence) code linearization at different operating points. In order to assure a smooth transition between the two regions, appropriate frequency-dependent varying scaling parametric weighting functions are designed in the LPV control structure. The solution of a set of linear matrix inequalities (LMIs) leads to the LPV controller. A synchronous generator model is connected with the closed LPV control loop for examining the electrical subsystem performance obtained by an inner speed control loop. Simulation results of a 1.5 MW horizontal axis wind turbine model on the FAST platform illustrates the benefit of the LPV control and demonstrates the advantages of this proposed LPV controller, when compared with a traditional gain scheduling PI control and prior LPV control configurations. Enhanced structural load mitigation, improved power extraction, and good current performance were obtained from the proposed LPV control. PMID:25884036
LPV control for the full region operation of a wind turbine integrated with synchronous generator.

PubMed

Cao, Guoyan; Grigoriadis, Karolos M; Nyanteh, Yaw D

2015-01-01

Wind turbine conversion systems require feedback control to achieve reliable wind turbine operation and stable current supply. A robust linear parameter varying (LPV) controller is proposed to reduce the structural loads and improve the power extraction of a horizontal axis wind turbine operating in both the partial load and the full load regions. The LPV model is derived from the wind turbine state space models extracted by FAST (fatigue, aerodynamics, structural, and turbulence) code linearization at different operating points. In order to assure a smooth transition between the two regions, appropriate frequency-dependent varying scaling parametric weighting functions are designed in the LPV control structure. The solution of a set of linear matrix inequalities (LMIs) leads to the LPV controller. A synchronous generator model is connected with the closed LPV control loop for examining the electrical subsystem performance obtained by an inner speed control loop. Simulation results of a 1.5 MW horizontal axis wind turbine model on the FAST platform illustrates the benefit of the LPV control and demonstrates the advantages of this proposed LPV controller, when compared with a traditional gain scheduling PI control and prior LPV control configurations. Enhanced structural load mitigation, improved power extraction, and good current performance were obtained from the proposed LPV control.
Performance prediction of asymmetrical bladed H-Darrieus VAWT rotors in low wind speed condition using CFD

NASA Astrophysics Data System (ADS)

Mazarbhuiya, Hussain Mahamed Sahed Mostafa; Biswas, Agnimitra; Sharma, Kaushal Kumar

2018-04-01

Wind energy is an essential and carbon free form of renewable energy resources. Energy can be easily extracted from wind with the use of Horizontal axis and Vertical axis wind turbine(VAWT). The performance of turbine depends on airfoil shape. The present work emphasizes the aerodynamics of different asymmetrical airfoils used in VAWT rotors. This investigation is conducted for the selection of efficient asymmetrical bladed H-Darrieus VAWT rotor. Five numbers of thick and cambered asymmetrical airfoil is considered for this investigation. A free stream velocity of 6.0 m/s is considered to simulate 2D CFD analysis using k-ɛ turbulence model. The power coefficient (Cp) of all H-Darrieus VAWT rotor increase with increase in TSR value to a certain limit and after it starts decrease with further increase of TSR. In the present investigation the Cp and TSR of NACA 63415 (RT-30%) are found to be higher among all considered asymmetrical airfoils. Moreover, Ct values of NACA 63415 (RT-30%) are also high corresponding to all TSR values. This is due to the long duration of attachment of flow with blade surroundings. Hence, NACA 63415 (RT- 30%) airfoil may be considered as an efficient airfoil among S818, GOE 561, GU25-5(11)8, and KENNEDY AND MARSDEN (kenmar) asymmetrical airfoils.
On Electron-Scale Whistler Turbulence in the Solar Wind

NASA Technical Reports Server (NTRS)

Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Giles, B.; Magnes, W.; Fischer, D.; Torbert, R. B.; Russell, C. T.

2016-01-01

For the first time, the dispersion relation for turbulence magnetic field fluctuations in the solar wind is determined directly on small scales of the order of the electron inertial length, using four-point magnetometer observations from the Magnetospheric Multiscale mission. The data are analyzed using the high-resolution adaptive wave telescope technique. Small-scale solar wind turbulence is primarily composed of highly obliquely propagating waves, with dispersion consistent with that of the whistler mode.
Studies of Sub-Synchronous Oscillations in Large-Scale Wind Farm Integrated System

NASA Astrophysics Data System (ADS)

Yue, Liu; Hang, Mend

2018-01-01

With the rapid development and construction of large-scale wind farms and grid-connected operation, the series compensation wind power AC transmission is gradually becoming the main way of power usage and improvement of wind power availability and grid stability, but the integration of wind farm will change the SSO (Sub-Synchronous oscillation) damping characteristics of synchronous generator system. Regarding the above SSO problem caused by integration of large-scale wind farms, this paper focusing on doubly fed induction generator (DFIG) based wind farms, aim to summarize the SSO mechanism in large-scale wind power integrated system with series compensation, which can be classified as three types: sub-synchronous control interaction (SSCI), sub-synchronous torsional interaction (SSTI), sub-synchronous resonance (SSR). Then, SSO modelling and analysis methods are categorized and compared by its applicable areas. Furthermore, this paper summarizes the suppression measures of actual SSO projects based on different control objectives. Finally, the research prospect on this field is explored.
D-558-1 on ramp with ground crew and NACA pilot Bob Champine

NASA Technical Reports Server (NTRS)

1949-01-01

NACA test pilot Robert Champine is seen in the cockpit of the Douglas D-558-1 Skystreak with the ground crew. Robert A. Champine was a research pilot with the National Advisory Committee for Aeronautics (NACA) and the National Aeronautics and Space Administration (NASA) from December 1947 to 1979, when he retired as Langley Research Center's senior research pilot. He began his career with the NACA at the Langley Memorial Aeronautical Laboratory in Hampton, Virginia (as Langley Research Center was then called). He transferred to the NACA's High-Speed Flight Research Station in the Mojave Desert of California in October 1948, where he flew the X-1 and D-558-1 and -2 research airplanes. On December 2, 1948, Bob became the 6th man and 3rd civilian to break the mysterious sound barrier. He exceeded Mach 1 on NACA flight 23 checking handling qualities and pressure distribution on the XS-1 #2, after having been dropped from the B-29 mother ship, above the Rogers Dry Lake in California. On August 4, 1949, NACA flight 32, he again exceeded Mach 1 performing rolls, pullups, sideslips, and check of stabilizer effectiveness. This was his 13th and last flight in the XS-1. He flew the first NACA research flight of the D-558-1 #3 (Skystreak) on April 22, 1949, and the first NACA research flight of the D-558-2 #2 (Skyrocket) on May 24, 1949, beginning the supersonic research program for these aircraft on June l, 1949. Conceived in 1945, the D558-1 Skystreak was designed by the Douglas Aircraft Company for the U.S. Navy Bureau of Aeronautics, in conjunction with the National Advisory Committee for Aeronautics (NACA). The Skystreaks were turojet powered aircraft that took off from the ground under their own power and had straight wings and tails. All three D-558-1 Skystreaks were powered by Allison J35-A-11 turbojet engines producing 5,000 pounds of thrust. All the Skystreaks were initially painted scarlet, which lead to the nickname 'crimson test tube.' NACA later had the color of
Wind Power Innovation Enables Shift to Utility-Scale - Continuum Magazine

Science.gov Websites

the 1930s, a farmer in South Dakota built a small wind turbine on his farm, generating enough enough electricity to power thousands of homes. Aerial photo of large wind turbine with mountains in the background. Aerial view of the Siemens utility-scale wind turbine at the National Wind Technology Center
Stellar feedback in galaxies and the origin of galaxy-scale winds

NASA Astrophysics Data System (ADS)

Hopkins, Philip F.; Quataert, Eliot; Murray, Norman

2012-04-01

Feedback from massive stars is believed to play a critical role in driving galactic super-winds that enrich the intergalactic medium and shape the galaxy mass function, mass-metallicity relation and other global galaxy properties. In previous papers, we have introduced new numerical methods for implementing stellar feedback on sub-giant molecular cloud (sub-GMC) through galactic scales in numerical simulations of galaxies; the key physical processes include radiation pressure in the ultraviolet through infrared, supernovae (Type I and Type II), stellar winds ('fast' O star through 'slow' asymptotic giant branch winds), and H II photoionization. Here, we show that these feedback mechanisms drive galactic winds with outflow rates as high as ˜10-20 times the galaxy star formation rate. The mass-loading efficiency (wind mass-loss rate divided by the star formation rate) scales roughly as ? (where Vc is the galaxy circular velocity), consistent with simple momentum-conservation expectations. We use our suite of simulations to study the relative contribution of each feedback mechanism to the generation of galactic winds in a range of galaxy models, from Small Magellanic Cloud like dwarfs and Milky Way (MW) analogues to z˜ 2 clumpy discs. In massive, gas-rich systems (local starbursts and high-z galaxies), radiation pressure dominates the wind generation. By contrast, for MW-like spirals and dwarf galaxies the gas densities are much lower and sources of shock-heated gas such as supernovae and stellar winds dominate the production of large-scale outflows. In all of our models, however, the winds have a complex multiphase structure that depends on the interaction between multiple feedback mechanisms operating on different spatial scales and time-scales: any single feedback mechanism fails to reproduce the winds observed. We use our simulations to provide fitting functions to the wind mass loading and velocities as a function of galaxy properties, for use in cosmological
Full-scale investigation of wind-induced vibrations of mast-arm traffic signal structures.

DOT National Transportation Integrated Search

2014-08-01

Because of their inherent : fl : exibility and low damping ratios, cantilevered mast : - : arm : tra : ffi : c signal structures are suscepti : b : le to : wind : - : induced vibrations. : These vibrations : cause stru : ctural stresses and strains t...

NACA Conference on Aircraft Loads, Structures, and Flutter

NASA Technical Reports Server (NTRS)

1957-01-01

This document contains reproductions of technical papers on some of the most recent research results on aircraft loads, flutter, and structures from the NACA laboratories. These papers were presented by members of the staff of the NACA laboratories at the Conference held at the Langley Aeronautical Laboratory March 5, 6, and 7, 1957. The primary purpose of this Conference was to convey to contractors of the military services and others concerned with the design of aircraft these recent research results and to provide those attending an opportunity to discuss the results. The papers in this document are in the same form in which they were presented at the Conference in order to facilitate their prompt distribution. The original presentation and this record are considered as complementary to, rather than as substitutes for, the Committee?s more complete and formal reports. Accordingly, if information from this document is utilized it is requested that this document not be listed as a reference. Individual reports dealing with most of the information presented at the Conference will subsequently be published by NACA and will therefore be suitable as reference material.
Wall interaction effects for a full-scale helicopter rotor in the NASA Ames 80- by 120-foot wind tunnel

NASA Technical Reports Server (NTRS)

Shinoda, Patrick M.

1994-01-01

A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. This wind tunnel test generated a unique and extensive data base covering a wide range of rotor shaft angles-of-attack and rotor thrust conditions from 0 to 100 knots. Three configurations were tested: (1) empty tunnel; (2) test stand body (fuselage) and support system; and (3) fuselage and support system with rotor installed. Empty tunnel wall pressure data are evaluated as a function of tunnel speed to understand the baseline characteristics. Aerodynamic interaction effects between the fuselage and the walls of the tunnel are investigated by comparing wall, ceiling, and floor pressures for various tunnel velocities and fuselage angles-of-attack. Aerodynamic interaction effects between the rotor and the walls of the tunnel are also investigated by comparing wall, ceiling, and floor pressures for various rotor shaft angles, rotor thrust conditions, and tunnel velocities. Empty tunnel wall pressure data show good repeatability and are not affected by tunnel speed. In addition, the tunnel wall pressure profiles are not affected by the presence of the fuselage apart from a pressure shift. Results do not indicate that the tunnel wall pressure profiles are affected by the presence of the rotor. Significant changes in the wall, ceiling, and floor pressure profiles occur with changing tunnel speeds for constant rotor thrust and shaft angle conditions. Significant changes were also observed when varying rotor thrust or rotor shaft angle-of-attack. Other results indicate that dynamic rotor loads and blade motion are influenced by the presence of the tunnel walls at very low tunnel velocity and, together with the wall pressure data, provide a good indication of flow breakdown.
Aerodynamic study of different cyclist positions: CFD analysis and full-scale wind-tunnel tests.

PubMed

Defraeye, Thijs; Blocken, Bert; Koninckx, Erwin; Hespel, Peter; Carmeliet, Jan

2010-05-07

Three different cyclist positions were evaluated with Computational Fluid Dynamics (CFD) and wind-tunnel experiments were used to provide reliable data to evaluate the accuracy of the CFD simulations. Specific features of this study are: (1) both steady Reynolds-averaged Navier-Stokes (RANS) and unsteady flow modelling, with more advanced turbulence modelling techniques (Large-Eddy Simulation - LES), were evaluated; (2) the boundary layer on the cyclist's surface was resolved entirely with low-Reynolds number modelling, instead of modelling it with wall functions; (3) apart from drag measurements, also surface pressure measurements on the cyclist's body were performed in the wind-tunnel experiment, which provided the basis for a more detailed evaluation of the predicted flow field by CFD. The results show that the simulated and measured drag areas differed about 11% (RANS) and 7% (LES), which is considered to be a close agreement in CFD studies. A fair agreement with wind-tunnel data was obtained for the predicted surface pressures, especially with LES. Despite the higher accuracy of LES, its much higher computational cost could make RANS more attractive for practical use in some situations. CFD is found to be a valuable tool to evaluate the drag of different cyclist positions and to investigate the influence of small adjustments in the cyclist's position. A strong advantage of CFD is that detailed flow field information is obtained, which cannot easily be obtained from wind-tunnel tests. This detailed information allows more insight in the causes of the drag force and provides better guidance for position improvements. Copyright 2010 Elsevier Ltd. All rights reserved.
Historical perspectives on thermostructural research at the NACA Langley Aeronautical Laboratory from 1948 to 1958

NASA Technical Reports Server (NTRS)

Heldenfels, R. R.

1982-01-01

Some of the early research on structural problems produced by aerodynamic heating, conducted at the Langley Aeronautical Laboratory of the National Advisory Committee for Aeronautics from 1948 to 1958 is described. That was the last decade of the NACA; in 1958 NACA became the nucleus of NASA. The NACA initially contracted for research but was aware that a well-equipped and suitably staffed laboratory was required to fulfill its obligations. Langley was established in 1920; the other listed were added during the NACA expansion in the World War II years. Some specific research activities are described, starting with calculation of the temperature of the structure.
Historical perspectives on thermostructural research at the NACA Langley Aeronautical Laboratory from 1948 to 1958

NASA Astrophysics Data System (ADS)

Heldenfels, R. R.

Some of the early research on structural problems produced by aerodynamic heating, conducted at the Langley Aeronautical Laboratory of the National Advisory Committee for Aeronautics from 1948 to 1958 is described. That was the last decade of the NACA; in 1958 NACA became the nucleus of NASA. The NACA initially contracted for research but was aware that a well-equipped and suitably staffed laboratory was required to fulfill its obligations. Langley was established in 1920; the other listed were added during the NACA expansion in the World War II years. Some specific research activities are described, starting with calculation of the temperature of the structure.
Hydrodynamic and Aerodynamic Tests of Models of Floats for Single-float Seaplanes NACA Models 41-D, 41-E, 61-A, 73, and 73-A

NASA Technical Reports Server (NTRS)

Parkinson, J B; HOUSE R O

1938-01-01

Tests were made in the NACA tank and in the NACA 7 by 10 foot wind tunnel on two models of transverse step floats and three models of pointed step floats considered to be suitable for use with single float seaplanes. The object of the program was the reduction of water resistance and spray of single float seaplanes without reducing the angle of dead rise believed to be necessary for the satisfactory absorption of the shock loads. The results indicated that all the models have less resistance and spray than the model of the Mark V float and that the pointed step floats are somewhat superior to the transverse step floats in these respects. Models 41-D, 61-A, and 73 were tested by the general method over a wide range of loads and speeds. The results are presented in the form of curves and charts for use in design calculations.
A method for modifying two-dimensional adaptive wind-tunnel walls including analytical and experimental verification

NASA Technical Reports Server (NTRS)

Everhart, J. L.

1983-01-01

The theoretical development of a simple and consistent method for removing the interference in adaptive-wall wind tunnels is reported. A Cauchy integral formulation of the velocities in an imaginary infinite extension of the real wind-tunnel flow is obtained and evaluated on a closed contour dividing the real and imaginary flow. The contour consists of the upper and lower effective wind-tunnel walls (wall plus boundary-layer displacement thickness) and upstream and downstream boundaries perpendicular to the axial tunnel flow. The resulting integral expressions for the streamwise and normal perturbation velocities on the contour are integrated by assuming a linear variation of the velocities between data-measurement stations along the contour. In an iterative process, the velocity components calculated on the upper and lower boundaries are then used to correct the shape of the wall to remove the interference. Convergence of the technique is shown numerically for the cases of a circular cylinder and a lifting and nonlifting NACA 0012 airfoil in incompressible flow. Experimental convergence at a transonic Mach number is demonstrated by using an NACA 0012 airfoil at zero lift.
Aerodynamic performance of a small vertical axis wind turbine using an overset grid method

NASA Astrophysics Data System (ADS)

Bangga, Galih; Solichin, Mochammad; Daman, Aida; Sa'adiyah, Devy; Dessoky, Amgad; Lutz, Thorsten

2017-08-01

The present paper aims to asses the aerodynamic performance of a small vertical axis wind turbine operating at a small wind speed of 5 m/s for 6 different tip speed ratios (λ=2-7). The turbine consists of two blades constructed using the NACA 0015 airfoil. The study is carried out using computational fluid dynamics (CFD) methods employing an overset grid approach. The (URANS) SST k - ω is used as the turbulence model. For the preliminary study, simulations of the NACA 0015 under static conditions for a broad range of angle of attack and a rotating two-bladed VAWT are carried out. The results are compared with available measurement data and a good agreement is obtained. The simulations demonstrate that the maximum power coefficient attained is 0.45 for λ=4. The aerodynamic loads hysteresis are presented showing that the dynamic stall effect decreases with λ.
Review of the Need for a Large-scale Test Facility for Research on the Effects of Extreme Winds on Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. G. Little

1999-03-01

The Idaho National Engineering and Environmental Laboratory (INEEL), through the US Department of Energy (DOE), has proposed that a large-scale wind test facility (LSWTF) be constructed to study, in full-scale, the behavior of low-rise structures under simulated extreme wind conditions. To determine the need for, and potential benefits of, such a facility, the Idaho Operations Office of the DOE requested that the National Research Council (NRC) perform an independent assessment of the role and potential value of an LSWTF in the overall context of wind engineering research. The NRC established the Committee to Review the Need for a Large-scale Testmore » Facility for Research on the Effects of Extreme Winds on Structures, under the auspices of the Board on Infrastructure and the Constructed Environment, to perform this assessment. This report conveys the results of the committee's deliberations as well as its findings and recommendations. Data developed at large-scale would enhanced the understanding of how structures, particularly light-frame structures, are affected by extreme winds (e.g., hurricanes, tornadoes, sever thunderstorms, and other events). With a large-scale wind test facility, full-sized structures, such as site-built or manufactured housing and small commercial or industrial buildings, could be tested under a range of wind conditions in a controlled, repeatable environment. At this time, the US has no facility specifically constructed for this purpose. During the course of this study, the committee was confronted by three difficult questions: (1) does the lack of a facility equate to a need for the facility? (2) is need alone sufficient justification for the construction of a facility? and (3) would the benefits derived from information produced in an LSWTF justify the costs of producing that information? The committee's evaluation of the need and justification for an LSWTF was shaped by these realities.« less
NACA: 25 Years of Flight Research

NASA Image and Video Library

2018-05-10

A narrated film documentary of flight tests at the NACA and NASA’s Flight Research Center shows the X-1, D-558-II, X-3, X-4, X-5, and X-15 in flight and on the ground. The story describes what each aircraft contributed to flight’s expansion.
Flow Separation Control on A Full-Scale Vertical Tail Model Using Sweeping Jet Actuators

NASA Technical Reports Server (NTRS)

Andino, Marlyn Y.; Lin, John C.; Washburn, Anthony E.; Whalen, Edward A.; Graff, Emilio C.; Wygnanski, Israel J.

2015-01-01

This paper describes test results of a joint NASA/Boeing research effort to advance Active Flow Control (AFC) technology to enhance aerodynamic efficiency. A full-scale Boeing 757 vertical tail model equipped with sweeping jets AFC was tested at the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel at NASA Ames Research Center. The flow separation control optimization was performed at 100 knots, a maximum rudder deflection of 30deg, and sideslip angles of 0deg and -7.5deg. Greater than 20% increments in side force were achieved at the two sideslip angles with a 31-actuator AFC configuration. Flow physics and flow separation control associated with the AFC are presented in detail. AFC caused significant increases in suction pressure on the actuator side and associated side force enhancement. The momentum coefficient (C sub mu) is shown to be a useful parameter to use for scaling-up sweeping jet AFC from sub-scale tests to full-scale applications. Reducing the number of actuators at a constant total C(sub mu) of approximately 0.5% and tripling the actuator spacing did not significantly affect the flow separation control effectiveness.
Identification of wind turbine testing practices and investigation of the performance benefits of closely-spaced lateral wind farm configurations

NASA Astrophysics Data System (ADS)

McTavish, Sean

The current thesis investigates the development of guidelines for testing small-scale wind turbines and identifies a method that can be used to increase the performance of wind farms. The research was conducted using two scaled wind turbine designs. The first design was a three-bladed wind turbine designed in the Department of Mechanical and Aerospace Engineering (MAAE) to operate in a low Reynolds number regime and to generate a thrust coefficient representative of commercial-scale wind turbines. An Eppler E387 airfoil was selected for the wind turbine due to its behaviour at low Reynolds numbers and the chord of the turbine was increased relative to full-scale designs in order to increase the range of Reynolds numbers that could be attained. The second design was a geometrically-scaled version of an existing two-bladed wind turbine with a NACA 0012 airfoil that was originally designed at the Delft University of Technology. Experiments were conducted in a 0.61 m x 0.81 m water channel in order to independently evaluate the effects of increasing blockage and Reynolds number on the development of the wind turbine wake. Quantitative dye visualisation was used to identify the position of tip vortex cores relative to the blade tip in order to assess how blockage and Reynolds number effects modified the initial expansion in the near wake. Blockage effects on the wake development were assessed using five wind turbines with diameters ranging from 20 cm to 40 cm, corresponding to blockage of 6.3% to 25.4%. The rotors were all operated at a similar tip speed ratio of 6 and a Reynolds number of 23,000 based on the blade tip speed and tip chord. One Outcome of the research was the identification of a limit beyond which blockage narrowed the expansion in the near wake of a wind turbine. It was observed that blockage should be maintained at less than 10% in order to prevent the wake from narrowing artificially due to the flow acceleration around the turbine caused by excessive
Computational Acoustic Beamforming for Noise Source Identification for Small Wind Turbines.

PubMed

Ma, Ping; Lien, Fue-Sang; Yee, Eugene

2017-01-01

This paper develops a computational acoustic beamforming (CAB) methodology for identification of sources of small wind turbine noise. This methodology is validated using the case of the NACA 0012 airfoil trailing edge noise. For this validation case, the predicted acoustic maps were in excellent conformance with the results of the measurements obtained from the acoustic beamforming experiment. Following this validation study, the CAB methodology was applied to the identification of noise sources generated by a commercial small wind turbine. The simulated acoustic maps revealed that the blade tower interaction and the wind turbine nacelle were the two primary mechanisms for sound generation for this small wind turbine at frequencies between 100 and 630 Hz.
Computational Acoustic Beamforming for Noise Source Identification for Small Wind Turbines

PubMed Central

Lien, Fue-Sang

2017-01-01

This paper develops a computational acoustic beamforming (CAB) methodology for identification of sources of small wind turbine noise. This methodology is validated using the case of the NACA 0012 airfoil trailing edge noise. For this validation case, the predicted acoustic maps were in excellent conformance with the results of the measurements obtained from the acoustic beamforming experiment. Following this validation study, the CAB methodology was applied to the identification of noise sources generated by a commercial small wind turbine. The simulated acoustic maps revealed that the blade tower interaction and the wind turbine nacelle were the two primary mechanisms for sound generation for this small wind turbine at frequencies between 100 and 630 Hz. PMID:28378012
Aeroelastic Stability Investigations for Large-scale Vertical Axis Wind Turbines

NASA Astrophysics Data System (ADS)

Owens, B. C.; Griffith, D. T.

2014-06-01

The availability of offshore wind resources in coastal regions, along with a high concentration of load centers in these areas, makes offshore wind energy an attractive opportunity for clean renewable electricity production. High infrastructure costs such as the offshore support structure and operation and maintenance costs for offshore wind technology, however, are significant obstacles that need to be overcome to make offshore wind a more cost-effective option. A vertical-axis wind turbine (VAWT) rotor configuration offers a potential transformative technology solution that significantly lowers cost of energy for offshore wind due to its inherent advantages for the offshore market. However, several potential challenges exist for VAWTs and this paper addresses one of them with an initial investigation of dynamic aeroelastic stability for large-scale, multi-megawatt VAWTs. The aeroelastic formulation and solution method from the BLade Aeroelastic STability Tool (BLAST) for HAWT blades was employed to extend the analysis capability of a newly developed structural dynamics design tool for VAWTs. This investigation considers the effect of configuration geometry, material system choice, and number of blades on the aeroelastic stability of a VAWT, and provides an initial scoping for potential aeroelastic instabilities in large-scale VAWT designs.
Aerodynamic data banks for Clark-Y, NACA 4-digit and NACA 16-series airfoil families

NASA Technical Reports Server (NTRS)

Korkan, K. D.; Camba, J., III; Morris, P. M.

1986-01-01

With the renewed interest in propellers as means of obtaining thrust and fuel efficiency in addition to the increased utilization of the computer, a significant amount of progress was made in the development of theoretical models to predict the performance of propeller systems. Inherent in the majority of the theoretical performance models to date is the need for airfoil data banks which provide lift, drag, and moment coefficient values as a function of Mach number, angle-of-attack, maximum thickness to chord ratio, and Reynolds number. Realizing the need for such data, a study was initiated to provide airfoil data banks for three commonly used airfoil families in propeller design and analysis. The families chosen consisted of the Clark-Y, NACA 16 series, and NACA 4 digit series airfoils. The various component of each computer code, the source of the data used to create the airfoil data bank, the limitations of each data bank, program listing, and a sample case with its associated input-output are described. Each airfoil data bank computer code was written to be used on the Amdahl Computer system, which is IBM compatible and uses Fortran.
Development of a large-scale, outdoor, ground-based test capability for evaluating the effect of rain on airfoil lift

NASA Technical Reports Server (NTRS)

Bezos, Gaudy M.; Campbell, Bryan A.

1993-01-01

A large-scale, outdoor, ground-based test capability for acquiring aerodynamic data in a simulated rain environment was developed at the Langley Aircraft Landing Dynamics Facility (ALDF) to assess the effect of heavy rain on airfoil performance. The ALDF test carriage was modified to transport a 10-ft-chord NACA 64210 wing section along a 3000-ft track at full-scale aircraft approach speeds. An overhead rain simulation system was constructed along a 525-ft section of the track with the capability of producing simulated rain fields of 2, 10, 30, and 40 in/hr. The facility modifications, the aerodynamic testing and rain simulation capability, the design and calibration of the rain simulation system, and the operational procedures developed to minimize the effect of wind on the simulated rain field and aerodynamic data are described in detail. The data acquisition and reduction processes are also presented along with sample force data illustrating the environmental effects on data accuracy and repeatability for the 'rain-off' test condition.
Wind speed reductions by large-scale wind turbine deployments lower turbine efficiencies and set low generation limits

PubMed Central

Miller, Lee M.; Kleidon, Axel

2016-01-01

Wind turbines generate electricity by removing kinetic energy from the atmosphere. Large numbers of wind turbines are likely to reduce wind speeds, which lowers estimates of electricity generation from what would be presumed from unaffected conditions. Here, we test how well wind power limits that account for this effect can be estimated without explicitly simulating atmospheric dynamics. We first use simulations with an atmospheric general circulation model (GCM) that explicitly simulates the effects of wind turbines to derive wind power limits (GCM estimate), and compare them to a simple approach derived from the climatological conditions without turbines [vertical kinetic energy (VKE) estimate]. On land, we find strong agreement between the VKE and GCM estimates with respect to electricity generation rates (0.32 and 0.37 We m−2) and wind speed reductions by 42 and 44%. Over ocean, the GCM estimate is about twice the VKE estimate (0.59 and 0.29 We m−2) and yet with comparable wind speed reductions (50 and 42%). We then show that this bias can be corrected by modifying the downward momentum flux to the surface. Thus, large-scale limits to wind power use can be derived from climatological conditions without explicitly simulating atmospheric dynamics. Consistent with the GCM simulations, the approach estimates that only comparatively few land areas are suitable to generate more than 1 We m−2 of electricity and that larger deployment scales are likely to reduce the expected electricity generation rate of each turbine. We conclude that these atmospheric effects are relevant for planning the future expansion of wind power. PMID:27849587
Full-scale semi-span tests of an advanced NLF business jet wing

NASA Technical Reports Server (NTRS)

Hahne, David E.; Jordan, Frank L., Jr.; Davis, Patrick J.; Muchmore, C. Byram

1987-01-01

An investigation has been conducted in the NASA Langley Research Center's 30- by 60-Foot Wind Tunnel on a full-scale semispan model to evaluate and document the low-speed, high-lift characteristics of a business-jet class wing utilizing the HSNLF(1)-0213 airfoil section and a single slotted flap system. In addition to the high-lift studies, evaluations of boundary layer transition effects, the effectiveness of a segmented leading-edge droop for improved stall/spin resistance, and roll control effectiveness with and without flap deflection were made. The wind-tunnel investigation showed that deployment of a single-slotted trailing-edge flap provided substantial increments in lift. Fixed transition studies indicated no adverse effects on lift and pitching-moment characteristics for either the cruise or landing configuration. Subscale roll damping tests also indicated that stall/spin resistance could be enhanced through the use of a properly designed leading-edge droop.
Turning Vanes inside the Altitude Wind Tunnel

NASA Image and Video Library

1944-02-21

Men stand in front of turning vanes inside the Altitude Wind Tunnel (AWT) at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory. The AWT was the only wind tunnel capable of testing full-size aircraft engines in simulated altitude conditions. A large wooden drive fan, located on the other side of these vanes, created wind speeds up to 500 miles per hour. The drive shaft connected the fan to the induction motor located in an adjacent building. Turning vanes were located in each corner of the rectangular tunnel to straighten the airflow and direct it around the corners. This set of vanes was located in the 31-foot-diameter southeast corner of the tunnel. These elliptical panels consisted of 36 to 42 vertical vanes that were supported by three horizontal supports. The individual vanes were 2.5 feet long and half-moon shaped. The panel of vanes was affixed to the curved corner rings of the tunnel. Each set of turning vanes had a moveable vane in the middle of the lower level for personnel access. Each set of vanes took weeks to assemble before they were installed during the summer of 1943. This publicity photograph was taken just weeks after the tunnel became operational in February 1944.

Rocket Propellant Talk at the 1957 NACA Lewis Inspection

NASA Image and Video Library

1957-10-21

A researcher works a demonstration board in the Rocket Engine Test Facility during the 1957 Inspection of the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory in Cleveland, Ohio. Representatives from the military, aeronautical industry, universities, and the press were invited to the laboratory to be briefed on the NACA’s latest research efforts and tour the test facilities. Over 1700 people visited the Lewis during the October 7-10, 1957 Inspection. The Soviet Union launched their first Sputnik satellite just days before on October 4. NACA Lewis had been involved in small rockets and propellants research since 1945, but the NACA leadership was wary of involving itself too deeply with the work since ballistics traditionally fell under the military’s purview. The Lewis research was performed by the High Temperature Combustion section in the Fuels and Lubricants Division in a series of small cinderblock test cells. The rocket group was expanded in 1952 and made several test runs in late 1954 using liquid hydrogen as a propellant. A larger test facility, the Rocket Engine Test Facility, was approved and became operational just in time for the Inspection.
Wind tunnels with adapted walls for reducing wall interference

NASA Technical Reports Server (NTRS)

Ganzer, U.

1979-01-01

The basic principle of adaptable wind tunnel walls is explained. First results of an investigation carried out at the Aero-Space Institute of Berlin Technical University are presented for two dimensional flexible walls and a NACA 0012 airfoil. With five examples exhibiting very different flow conditions it is demonstrated that it is possible to reduce wall interference and to avoid blockage at transonic speeds by wall adaptation.
Natural snowfall reveals large-scale flow structures in the wake of a 2.5-MW wind turbine.

PubMed

Hong, Jiarong; Toloui, Mostafa; Chamorro, Leonardo P; Guala, Michele; Howard, Kevin; Riley, Sean; Tucker, James; Sotiropoulos, Fotis

2014-06-24

To improve power production and structural reliability of wind turbines, there is a pressing need to understand how turbines interact with the atmospheric boundary layer. However, experimental techniques capable of quantifying or even qualitatively visualizing the large-scale turbulent flow structures around full-scale turbines do not exist today. Here we use snowflakes from a winter snowstorm as flow tracers to obtain velocity fields downwind of a 2.5-MW wind turbine in a sampling area of ~36 × 36 m(2). The spatial and temporal resolutions of the measurements are sufficiently high to quantify the evolution of blade-generated coherent motions, such as the tip and trailing sheet vortices, identify their instability mechanisms and correlate them with turbine operation, control and performance. Our experiment provides an unprecedented in situ characterization of flow structures around utility-scale turbines, and yields significant insights into the Reynolds number similarity issues presented in wind energy applications.
Size Reduction Techniques for Large Scale Permanent Magnet Generators in Wind Turbines

NASA Astrophysics Data System (ADS)

Khazdozian, Helena; Hadimani, Ravi; Jiles, David

2015-03-01

Increased wind penetration is necessary to reduce U.S. dependence on fossil fuels, combat climate change and increase national energy security. The U.S Department of Energy has recommended large scale and offshore wind turbines to achieve 20% wind electricity generation by 2030. Currently, geared doubly-fed induction generators (DFIGs) are typically employed in the drivetrain for conversion of mechanical to electrical energy. Yet, gearboxes account for the greatest downtime of wind turbines, decreasing reliability and contributing to loss of profit. Direct drive permanent magnet generators (PMGs) offer a reliable alternative to DFIGs by eliminating the gearbox. However, PMGs scale up in size and weight much more rapidly than DFIGs as rated power is increased, presenting significant challenges for large scale wind turbine application. Thus, size reduction techniques are needed for viability of PMGs in large scale wind turbines. Two size reduction techniques are presented. It is demonstrated that 25% size reduction of a 10MW PMG is possible with a high remanence theoretical permanent magnet. Additionally, the use of a Halbach cylinder in an outer rotor PMG is investigated to focus magnetic flux over the rotor surface in order to increase torque. This work was supported by the National Science Foundation under Grant No. 1069283 and a Barbara and James Palmer Endowment at Iowa State University.
Acoustic measurements of a full-scale coaxial hingeless rotor helicopter

NASA Technical Reports Server (NTRS)

Peterson, R. L.; Mosher, M.

1983-01-01

Acoustic data were obtained during a full-scale test of the XH-59A Advancing Blade Concept Technology Demonstrator in the 40- by 80-Foot Wind Tunnel. The XH-59A is a research helicopter with two coaxial rotors and hingeless blades. Performance, vibration, and noise at various forward speeds, rotor lift coefficients and rotor shaft angles of attack were investigated. The noise data were acquired over an isolated rotor lift coefficient range of 0.024 to 0.162, an advance ratio range of 0.23 to 0.45 corresponding to tunnel wind speeds of 89 to 160 knots, and angles of attack from 0 deg to 10 deg. Acoustic data are presented for seven microphone locations for all run conditions where the model noise is above the background noise. Model test configuration and performance information are also listed. Acoustic waveforms, dBA, and 1/3-octave spectra as functions of operating condition for selected data points and microphones are presented. In general, the noise level is shown to increase with rotor lift coefficient except under certain operating conditions where significant impulsive blade/vortex interactions increase noise levels.
An Investigation of the Drag of Windshields in the 8-foot High-Speed Wind Tunnel

NASA Technical Reports Server (NTRS)

Robinson, Russell G; Delano, James B

1942-01-01

Report presents the results of tests made to determine the drag of closed-cockpit and transport-type windshields. The tests were made at speeds corresponding to a Mach number range of approximately 0.25 to 0.58 in the NACA 8-foot high-speed wind tunnel. This speed range corresponds to a test Reynolds number range of 2,510,000 to 4,830,000 based on the mean aerodynamic chord of the full-span model (17.29 in.). The shapes of the windshield proper, the hood, and the tail fairing were systematically varied to include common types and refined design.
Full-scale wind-tunnel test of the aeroelastic stability of a bearingless main rotor

NASA Technical Reports Server (NTRS)

Warmbrodt, W.; Mccloud, J., III; Sheffler, M.; Staley, J.

1981-01-01

The rotor studied in the wind tunnel had previously been flight tested on a BO-105 helicopter. The investigation was conducted to determine the rotor's aeroelastic stability characteristics in hover and at airspeeds up to 143 knots. These characteristics are compared with those obtained from whirl-tower and flight tests and predictions from a digital computer simulation. It was found that the rotor was stable for all conditions tested. At constant tip speed, shaft angle, and airspeed, stability increases with blade collective pitch setting. No significant change in system damping occurred that was attributable to frequency coalescence between the rotor inplane regressing mode and the support modes. Stability levels determined in the wind tunnel were of the same magnitude and yielded the same trends as data obtained from whirl-tower and flight tests.
Large Swing Valve in the 10- by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1956-05-21

A 24-foot diameter swing valve is seen in an open position inside the new 10- by 10-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The 10- by 10 was the most powerful propulsion wind tunnel in the nation. After over three years of construction the tunnel was ready to conduct its first tests in early 1956. The 10- by 10-foot tunnel was part of Congress’ Unitary Plan Act which coordinated wind tunnel construction at the NACA, Air Force, industry, and universities. The 10- by 10 was the largest of the three NACA tunnels built under the act. This large swinging valve is critical to the operation of the facility. In one position the valve seals off the tunnel exhaust, making the tunnel a closed circuit, which is used for aerodynamic testing of models. In its other position, the valve acts as a seal across the tunnel and leaves the tunnel exhaust open. This arrangement is used when engines are fired. The air going through the tunnel is taken from the atmosphere and returned to the atmosphere after one pass through the tunnel. Engines up to five feet in diameter can be tested in the 10- by 10-foot test section. Air flows up to Mach 3.5 can be fed through the test section by a 250,000-horsepower axial-flow compressor fan. The incoming air must be dehumidified and cooled so that the proper conditions are present for the test. A large air dryer with 1,890 tons of activated alumina soaks up 1.5 tons of water per minute from the air flow. A cooling apparatus equivalent to 250,000 household air conditioners is used to cool the air.
Wind speed reductions by large-scale wind turbine deployments lower turbine efficiencies and set low generation limits.

PubMed

Miller, Lee M; Kleidon, Axel

2016-11-29

Wind turbines generate electricity by removing kinetic energy from the atmosphere. Large numbers of wind turbines are likely to reduce wind speeds, which lowers estimates of electricity generation from what would be presumed from unaffected conditions. Here, we test how well wind power limits that account for this effect can be estimated without explicitly simulating atmospheric dynamics. We first use simulations with an atmospheric general circulation model (GCM) that explicitly simulates the effects of wind turbines to derive wind power limits (GCM estimate), and compare them to a simple approach derived from the climatological conditions without turbines [vertical kinetic energy (VKE) estimate]. On land, we find strong agreement between the VKE and GCM estimates with respect to electricity generation rates (0.32 and 0.37 W e m -2 ) and wind speed reductions by 42 and 44%. Over ocean, the GCM estimate is about twice the VKE estimate (0.59 and 0.29 W e m -2 ) and yet with comparable wind speed reductions (50 and 42%). We then show that this bias can be corrected by modifying the downward momentum flux to the surface. Thus, large-scale limits to wind power use can be derived from climatological conditions without explicitly simulating atmospheric dynamics. Consistent with the GCM simulations, the approach estimates that only comparatively few land areas are suitable to generate more than 1 W e m -2 of electricity and that larger deployment scales are likely to reduce the expected electricity generation rate of each turbine. We conclude that these atmospheric effects are relevant for planning the future expansion of wind power.
Investigation of Bearing Axial Cracking: Benchtop and Full-Scale Test Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, Jonathan A.; Gould, Benjamin; Greco, Aaron

2017-08-16

The most common failure mode in wind turbine gearboxes is axial cracking in intermediate and high-speed-stage bearings, also commonly called white-etching cracks (WECs). Although these types of cracks have been reported for over a decade, the conditions leading to WECs, the process by which this failure culminates, and the reasons for their apparent prevalence in wind turbine gearboxes are all highly debated. This paper summarizes the state of a multipronged research effort to examine the causes of WECs in wind turbine gearbox bearings. Recent efforts have recreated WECs on a benchtop test rig in highly loaded sliding conditions, wherein itmore » was found that the formation of a dark etching microstructure precedes the formation of a crack, and a crack precedes the formation of white-etching microstructure. A cumulative frictional sliding energy criterion has been postulated to predict the presence of WECs. Bearing loads have also been measured and predicted in steady state and transient drivetrain operations in dynamometer testing. In addition, both loads and sliding at full scale will be measured in planned uptower drivetrain testing. If the cumulative frictional sliding energy is the dominant mechanism that causes WECs, understanding the amount of frictional sliding energy that wind turbine bearings are subjected to in typical operations is the next step in the investigation. If highly loaded sliding conditions are found uptower, similar to the examined benchtop levels, appropriate mitigation solutions can be examined, ranging from new bearing coatings and improved lubricants to changes in gearbox designs and turbine operations.« less
Flying with the wind: scale dependency of speed and direction measurements in modelling wind support in avian flight.

PubMed

Safi, Kamran; Kranstauber, Bart; Weinzierl, Rolf; Griffin, Larry; Rees, Eileen C; Cabot, David; Cruz, Sebastian; Proaño, Carolina; Takekawa, John Y; Newman, Scott H; Waldenström, Jonas; Bengtsson, Daniel; Kays, Roland; Wikelski, Martin; Bohrer, Gil

2013-01-01

Understanding how environmental conditions, especially wind, influence birds' flight speeds is a prerequisite for understanding many important aspects of bird flight, including optimal migration strategies, navigation, and compensation for wind drift. Recent developments in tracking technology and the increased availability of data on large-scale weather patterns have made it possible to use path annotation to link the location of animals to environmental conditions such as wind speed and direction. However, there are various measures available for describing not only wind conditions but also the bird's flight direction and ground speed, and it is unclear which is best for determining the amount of wind support (the length of the wind vector in a bird's flight direction) and the influence of cross-winds (the length of the wind vector perpendicular to a bird's direction) throughout a bird's journey. We compared relationships between cross-wind, wind support and bird movements, using path annotation derived from two different global weather reanalysis datasets and three different measures of direction and speed calculation for 288 individuals of nine bird species. Wind was a strong predictor of bird ground speed, explaining 10-66% of the variance, depending on species. Models using data from different weather sources gave qualitatively similar results; however, determining flight direction and speed from successive locations, even at short (15 min intervals), was inferior to using instantaneous GPS-based measures of speed and direction. Use of successive location data significantly underestimated the birds' ground and airspeed, and also resulted in mistaken associations between cross-winds, wind support, and their interactive effects, in relation to the birds' onward flight. Wind has strong effects on bird flight, and combining GPS technology with path annotation of weather variables allows us to quantify these effects for understanding flight behaviour. The
Standardization Tests of NACA No. 1 Wind Tunnel

NASA Technical Reports Server (NTRS)

Reid, Elliott G

1925-01-01

The tests described in this report were made in the 5-foot atmospheric wind tunnel of the National Advisory Committee for Aeronautics, at Langley Field. The primary objective of collecting data on the characteristics of this tunnel for comparison with those of others throughout the world, in order that, in the future, the results of tests made in all the principle laboratories may be interpreted, compared, and coordinated on a basis of scientifically established relationships, a process hitherto impossible due to the lack of comparable data. The work includes tests of a disk, spheres, cylinders, and airfoils, explorations of the test section for static pressure and velocity distribution, and determination of the variations of air flow direction throughout the operating range of the tunnel. (author)
78 FR 11152 - Utility Scale Wind Towers from the People's Republic of China: Countervailing Duty Order

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-15

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-982] Utility Scale Wind Towers...''), the Department is issuing a countervailing duty order on utility scale wind towers (``wind towers..., 2012, the Department published the final determination in the countervailing duty investigation of wind...
Inspection of the New 10- by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1956-05-21

Attendees listen during the May 22, 1956 Inspection of the new 10- by 10-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The facility, known at the time as the Lewis Unitary Plan Tunnel, was in its initial stages of operation. The $33 million 10- by 10 was the most powerful wind tunnel in the nation. Over 150 guests from industry, other NACA laboratories, and the media attended the event. The speakers, from left to right in the front row, addressed the crowd before the tour. Lewis Director Raymond Sharp began the event by welcoming the visitors to the laboratory. NACA Director Hugh Dryden discussed Congress’ Unitary Plan Act and its effect on the creation of the facility. Lewis Associate Director Abe Silverstein discussed the need for research tools and the 10- by 10’s place among the NACA’s other research facilities. Lewis Assistant Director Eugene Wasielewski described the detailed design work that went into the facility. Carl Schueller, Chief of the 10- by 10, described the tunnel’s components and how the facility operated. Robert Godman led the tour afterwards. The 10- by 10 can test engines up to five feet in diameter at supersonic speeds and simulated altitudes of 30 miles. Its main purpose is to investigate problems relating to engine inlet and outlet geometry, engine matching and interference effects, and overall drag. The tunnel’s 250,000-horsepower electric motor drive, the most powerful of its kind in the world, creates air speeds between Mach 2.0 and 3.5.
CFD Study of NACA 0018 Airfoil with Flow Control

NASA Technical Reports Server (NTRS)

Eggert, Christopher A.; Rumsey, Christopher L.

2017-01-01

The abilities of two different Reynolds-Averaged Navier-Stokes codes to predict the effects of an active flow control device are evaluated. The flow control device consists of a blowing slot located on the upper surface of an NACA 0018 airfoil, near the leading edge. A second blowing slot present on the airfoil near mid-chord is not evaluated here. Experimental results from a wind tunnel test show that a slot blowing with high momentum coefficient will increase the lift of the airfoil (compared to no blowing) and delay flow separation. A slot with low momentum coefficient will decrease the lift and induce separation even at low angles of attack. Two codes, CFL3D and FUN3D, are used in two-dimensional computations along with several different turbulence models. Two of these produced reasonable results for this flow, when run fully turbulent. A more advanced transition model failed to predict reasonable results, but warrants further study using different inputs. Including inviscid upper and lower tunnel walls in the simulations was found to be important in obtaining pressure distributions and lift coefficients that best matched experimental data. A limited number of three-dimensional computations were also performed.
Aerodynamics of small-scale vertical-axis wind turbines

NASA Astrophysics Data System (ADS)

Paraschivoiu, I.; Desy, P.

1985-12-01

The purpose of this work is to study the influence of various rotor parameters on the aerodynamic performance of a small-scale Darrieus wind turbine. To do this, a straight-bladed Darrieus rotor is calculated by using the double-multiple-streamtube model including the streamtube expansion effects through the rotor (CARDAAX computer code) and the dynamicstall effects. The straight-bladed Darrieus turbine is as expected more efficient with respect the curved-bladed rotor but for a given solidity is operates at higher wind speeds.
Ordered roughness effects on NACA 0026 airfoil

NASA Astrophysics Data System (ADS)

Harun, Z.; Abbas, A. A.; Dheyaa, R. Mohammed; Ghazali, M. I.

2016-10-01

The effects of highly-ordered rough surface - riblets, applied onto the surface of a NACA 0026 airfoil, are investigated experimentally using wind tunnel. The riblets are arranged in directionally converging - diverging pattern with dimensions of height, h = 1 mm, pitch or spacing, s = 1 mm, yaw angle α = 0o and 10o The airfoil with external geometry of 500 mm span, 600 mm chord and 156 mm thickness has been built using mostly woods and aluminium. Turbulence quantities are collected using hotwire anemometry. Hotwire measurements show that flows past converging and diverging pattern inherit similar patterns in the near-wall region for both mean velocity and turbulence intensities profiles. The mean velocity profiles in logarithmic regions for both flows past converging and diverging riblet pattern are lower than that with yaw angle α = 0o. Converging riblets cause the boundary layer to thicken and the flow with yaw angle α = 0o produces the thinnest boundary layer. Both the converging and diverging riblets cause pronounced outer peaks in the turbulence intensities profiles. Most importantly, flows past converging and diverging pattern experience 30% skin friction reductions. Higher order statistics show that riblet surfaces produce similar effects due to adverse pressure gradient. It is concluded that a small strip of different ordered roughness features applied at a leading edge of an airfoil can change the turbulence characteristics dramatically.
Multifractal scaling of the kinetic energy flux in solar wind turbulence

NASA Technical Reports Server (NTRS)

Marsch, E.; Rosenbauer, H.; Tu, C.-Y.

1995-01-01

The geometrical and scaling properties of the energy flux of the turbulent kinetic energy in the solar wind have been studied. By present experimental technology in solar wind measurements, we cannot directly measure the real volumetric dissipation rate, epsilon(t), but are constrained to represent it by surrogating the energy flux near the dissipation range at the proton gyro scales. There is evidence for the multifractal nature of the so defined dissipation field epsilon(t), a result derived from the scaling exponents of its statistical q-th order moments. The related generalized dimension D(q) has been determined and reveals that the dissipation field has a multifractal structure. which is not compatible with a scale-invariant cascade. The associated multifractal spectrum f(alpha) has been estimated for the first time for MHD turbulence in the solar wind. Its features resemble those obtained for turbulent fluids and other nonlinear multifractal systems. The generalized dimension D(q) can, for turbulence in high-speed streams, be fitted well by the functional dependence of the p-model with a comparatively large parameter, p = 0.87. indicating a strongly intermittent multifractal energy cascade. The experimental value for D(p)/3, if used in the scaling exponent s(p) of the velocity structure function, gives an exponent that can describe some of the observations. The scaling exponent mu of the auto correlation function of epsilon(t) has also been directly evaluated. It has the value of 0.37. Finally. the mean dissipation rate was determined, which could be used in solar wind heating models.
Active flow control for a NACA-0012 profile

NASA Astrophysics Data System (ADS)

Oualli, H.; Mekadem, M.; Boukrif, M.; Saad, S.; Bouabdallah, A.; Gad-El-Hak, M.

2015-11-01

Active flow control is applied on a NACA-0012 profile. The experiments are carried out in a wind tunnel, and flow visualizations are conducted using high-resolution visible-light and infrared cameras. Numerical LES finite-volume code is used to complement the physical experiments. The symmetric wing is clipped into two parts, and those parts extend and retract along the chord according to the same sinusoidal law we optimized last year for a circular/elliptical cylinder (B. Am. Phys. Soc., vol. 59, no. 20, p. 319, 2014). The Reynolds number varies in the range of 500-100,000, which is typical of UAVs and micro-UAVs. The nascent cavity resulting from the oscillatory motion of the profile segments is kept open allowing the passage of fluid between the intrados and extrados. The pulsatile motion is characterized by an amplitude and frequency, and the airfoil's angle of attack is changed in the range of 0-30 deg. For certain amplitude and frequency, the drag coefficient is increased over the uncontrolled case by a factor of 300. But when the cavity is covered to prevent the flow from passing through the cavity, the drag coefficient becomes negative, and significant thrust is produced. The results are promising to achieve rapid deceleration and acceleration of UAVs.
78 FR 11146 - Utility Scale Wind Towers From the People's Republic of China: Antidumping Duty Order

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-15

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-981] Utility Scale Wind Towers...''), the Department is issuing an antidumping duty order on utility scale wind towers (``wind towers... investigation of wind towers from the PRC.\\1\\ On February 8, 2013, the ITC notified the Department of its...

Investigation of the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 Two-Blade Propellers at Forward Mach Numbers to 0.725 to Determine the Effects of Camber and Compressibility on Performance

NASA Technical Reports Server (NTRS)

Delano, James B

1951-01-01

As part of a general investigation of propellers at high forward speeds, tests of two-blade propellers having the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 blade designs were made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.70 to determine the effect of camber and compressibility on propeller characteristics. Results previously reported for similar tests of a two-blade propeller having the NACA 4-(3)(08)-03 blade design are included for comparison.
Potential climatic impacts and reliability of very large-scale wind farms

NASA Astrophysics Data System (ADS)

Wang, C.; Prinn, R. G.

2010-02-01

Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG) emission technologies such as wind energy. The widespread availability of wind power has fueled substantial interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1 °C over land installations. In contrast, surface cooling exceeding 1 °C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure reliability
Potential climatic impacts and reliability of very large-scale wind farms

NASA Astrophysics Data System (ADS)

Wang, C.; Prinn, R. G.

2009-09-01

Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG) emission technologies such as wind energy. The widespread availability of wind power has fueled legitimate interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1°C over land installations. In contrast, surface cooling exceeding 1°C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure reliability, including
Flying with the wind: Scale dependency of speed and direction measurements in modelling wind support in avian flight

USGS Publications Warehouse

Safi, Kamran; Kranstauber, Bart; Weinzierl, Rolf P.; Griffin, Larry; Reese, Eileen C.; Cabot, David; Cruz, Sebastian; Proaño, Carolina; Takekawa, John Y.; Newman, Scott H.; Waldenström, Jonas; Bengtsson, Daniel; Kays, Roland; Wikelski, Martin; Bohrer, Gil

2013-01-01

Background: Understanding how environmental conditions, especially wind, influence birds' flight speeds is a prerequisite for understanding many important aspects of bird flight, including optimal migration strategies, navigation, and compensation for wind drift. Recent developments in tracking technology and the increased availability of data on large-scale weather patterns have made it possible to use path annotation to link the location of animals to environmental conditions such as wind speed and direction. However, there are various measures available for describing not only wind conditions but also the bird's flight direction and ground speed, and it is unclear which is best for determining the amount of wind support (the length of the wind vector in a bird’s flight direction) and the influence of cross-winds (the length of the wind vector perpendicular to a bird’s direction) throughout a bird's journey.Results: We compared relationships between cross-wind, wind support and bird movements, using path annotation derived from two different global weather reanalysis datasets and three different measures of direction and speed calculation for 288 individuals of nine bird species. Wind was a strong predictor of bird ground speed, explaining 10-66% of the variance, depending on species. Models using data from different weather sources gave qualitatively similar results; however, determining flight direction and speed from successive locations, even at short (15 min intervals), was inferior to using instantaneous GPS-based measures of speed and direction. Use of successive location data significantly underestimated the birds' ground and airspeed, and also resulted in mistaken associations between cross-winds, wind support, and their interactive effects, in relation to the birds' onward flight.Conclusions: Wind has strong effects on bird flight, and combining GPS technology with path annotation of weather variables allows us to quantify these effects for
Synoptic scale wind field properties from the SEASAT SASS

NASA Technical Reports Server (NTRS)

Pierson, W. J., Jr.; Sylvester, W. B.; Salfi, R. E.

1984-01-01

Dealiased SEASAT SEASAT A Scatterometer System SASS vector winds obtained during the Gulf Of Alaska SEASAT Experiment GOASEX program are processed to obtain superobservations centered on a one degree by one degree grid. The grid. The results provide values for the combined effects of mesoscale variability and communication noise on the individual SASS winds. These superobservations winds are then processed further to obtain estimates of synoptic scale vector winds stress fields, the horizontal divergence of the wind, the curl of the wind stress and the vertical velocity at 200 m above the sea surface, each with appropriate standard deviations of the estimates for each grid point value. They also explain the concentration of water vapor, liquid water and precipitation found by means of the SMMR Scanning Multichannel Microwave Radiometer at fronts and occlusions in terms of strong warm, moist air advection in the warm air sector accompanied by convergence in the friction layer. Their quality is far superior to that of analyses based on conventional data, which are shown to yield many inconsistencies.
The measurement of the synoptic scale wind over the ocean

NASA Technical Reports Server (NTRS)

Pierson, W. J.

1982-01-01

Mesoscale and microscale features of the turbulent winds over the ocean are related to the synoptic scale winds in terms of published spectral forms for the microscale, a mesoscale valley and published values of U*, VAR u', VAR v' and z/L, as defined in the text and as obtained for moderate to gale force winds. The frequencies involved correspond to periods longer than 1 hour and extend to the microscale, which starts at a period near 2 minutes, or so, and continues to the Kolmogorov inertial range. Nondimensional spectra that span both the mesoscale and the microscale are derived as a function of u, f(= n z/u) and z/L, where z is 10 meters, L is the Monin Obukov stability length and u is evaluated at 10 meters. For the same u, different values of z/L produce a range of values of u which in turn result in variations of the eddy structure of the mesoscale and microscale spectra. Both conventional anemometer averages and remotely sensed winds contain a random component of the mesoscale wind in their values. These components are differnces and not errors when winds are compared, and quantitative values for these differences are given. Ways to improve the measurement of the synoptic scale wind by transient ships, data buoys and scatterometers on future spacecraft are described. These ways are loner averaging times for ships and data buoys, depending on the synoptic conditions, and pooling spacecraft to form super observations. Design considerations for future remote sensing systems are given.
Role of Na+/Ca2+ Exchangers in Therapy Resistance of Medulloblastoma Cells.

PubMed

Pelzl, Lisann; Hosseinzadeh, Zohreh; Al-Maghout, Tamer; Singh, Yogesh; Sahu, Itishri; Bissinger, Rosi; Schmidt, Sebastian; Alkahtani, Saad; Stournaras, Christos; Toulany, Mahmoud; Lang, Florian

2017-01-01

Alterations of cytosolic Ca2+-activity ([Ca2+]i) are decisive in the regulation of tumor cell proliferation, migration and survival. Transport processes participating in the regulation of [Ca2+]i include Ca2+ extrusion through K+-independent (NCX) and/or K+-dependent (NCKX) Na+/Ca2+-exchangers. The present study thus explored whether medulloblastoma cells express Na+/Ca2+-exchangers, whether expression differs between therapy sensitive D283 and therapy resistant UW228-3 medulloblastoma cells, and whether Na+/Ca2+-exchangers participate in the regulation of cell survival. In therapy sensitive D283 and therapy resistant UW228-3 medulloblastoma cells transcript levels were estimated by RT-PCR, protein abundance by Western blotting, cytosolic Ca2+-activity ([Ca2+]i) from Fura-2-fluorescence, Na+/ Ca2+-exchanger activity from the increase of [Ca2+]i (Δ[Ca2+]i) and from whole cell current (Ica) following abrupt replacement of Na+ containing (130 mM) and Ca2+ free by Na+ free and Ca2+ containing (2 mM) extracellular perfusate as well as cell death from PI -staining and annexin-V binding in flow cytometry. The transcript levels of NCX3, NCKX2, and NCKX5, protein abundance of NCX3, slope and peak of Δ[Ca2+]i as well as Ica were significantly lower in therapy sensitive D283 than in therapy resistant UW228-3 medulloblastoma cells. The Na+/Ca2+-exchanger inhibitor KB-R7943 (10 µM) significantly blunted Δ[Ca2+]i, and augmented the ionizing radiation-induced apoptosis but did not significantly modify clonogenicity of medulloblastoma cells. Apoptosis was further enhanced by NCX3 silencing. Na+/Ca2+-exchanger activity significantly counteracts apoptosis but does not significantly affect clonogenicity after radiation of medulloblastoma cells. © 2017 The Author(s). Published by S. Karger AG, Basel.
Summary Report on the High-Speed Characteristics of Six Model Wings Having NACA 65sub1-Series Sections

NASA Technical Reports Server (NTRS)

Hamilton, William T; Nelson, Warren H

1947-01-01

A summary of the results of wind-tunnel tests to determine the high-speed aerodynamic characteristics of six model wings having NACA 65sub1-series sections is presented in this report. The 8-percent-thick wings were superior to the 10-percent and 12-percent-thick wings from the standpoint of power economy during level flight for Mach numbers above 0.76. However, airplanes that are to fly at Mach numbers below 0.76 will gain aerodynamically if the percentage thickness of the wing and the aspect ratio are both increased. The lift-curve slopes for the 8-percent-thick wings at 0.85 Mach number were roughly twice their low-speed values.
The economics and environmental impacts of large-scale wind power in a carbon constrained world

NASA Astrophysics Data System (ADS)

Decarolis, Joseph Frank

Serious climate change mitigation aimed at stabilizing atmospheric concentrations of CO2 will require a radical shift to a decarbonized energy supply. The electric power sector will be a primary target for deep reductions in CO2 emissions because electric power plants are among the largest and most manageable point sources of emissions. With respect to new capacity, wind power is currently one of the most inexpensive ways to produce electricity without CO2 emissions and it may have a significant role to play in a carbon constrained world. Yet most research in the wind industry remains focused on near term issues, while energy system models that focus on century-long time horizons undervalue wind by imposing exogenous limits on growth. This thesis fills a critical gap in the literature by taking a closer look at the cost and environmental impacts of large-scale wind. Estimates of the average cost of wind generation---now roughly 4¢/kWh---do not address the cons arising from the spatial distribution and intermittency of wind. This thesis develops a theoretical framework for assessing the intermittency cost of wind. In addition, an economic characterization of a wind system is provided in which long-distance electricity transmission, storage, and gas turbines are used to supplement variable wind power output to meet a time-varying load. With somewhat optimistic assumptions about the cost of wind turbines, the use of wind to serve 50% of demand adds ˜1--2¢/kWh to the cost of electricity, a cost comparable to that of other large-scale low carbon technologies. This thesis also explores the environmental impacts posed by large-scale wind. Though avian mortality and noise caused controversy in the early years of wind development, improved technology and exhaustive siting assessments have minimized their impact. The aesthetic valuation of wind farms can be improved significantly with better design, siting, construction, and maintenance procedures, but opposition may
The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

NASA Astrophysics Data System (ADS)

Rostamzadeh, N.; Hansen, K. L.; Kelso, R. M.; Dally, B. B.

2014-10-01

Wings with tubercles have been shown to display advantageous loading behavior at high attack angles compared to their unmodified counterparts. In an earlier study by the authors, it was shown that an undulating leading-edge configuration, including but not limited to a tubercled model, induces a cyclic variation in circulation along the span that gives rise to the formation of counter-rotating streamwise vortices. While the aerodynamic benefits of full-span tubercled wings have been associated with the presence of such vortices, their formation mechanism and influence on wing performance are still in question. In the present work, experimental and numerical tests were conducted to further investigate the effect of tubercles on the flow structure over full-span modified wings based on the NACA 0021 profile, in the transitional flow regime. It is found that a skew-induced mechanism accounts for the formation of streamwise vortices whose development is accompanied by flow separation in delta-shaped regions near the trailing edge. The presence of vortices is detrimental to the performance of full-span wings pre-stall, however renders benefits post-stall as demonstrated by wind tunnel pressure measurement tests. Finally, primary and secondary vortices are identified post-stall that produce an enhanced momentum transfer effect that reduces flow separation, thus increasing the generated amount of lift.
Large-Eddy Simulation of Waked Turbines in a Scaled Wind Farm Facility

NASA Astrophysics Data System (ADS)

Wang, J.; McLean, D.; Campagnolo, F.; Yu, T.; Bottasso, C. L.

2017-05-01

The aim of this paper is to present the numerical simulation of waked scaled wind turbines operating in a boundary layer wind tunnel. The simulation uses a LES-lifting-line numerical model. An immersed boundary method in conjunction with an adequate wall model is used to represent the effects of both the wind turbine nacelle and tower, which are shown to have a considerable effect on the wake behavior. Multi-airfoil data calibrated at different Reynolds numbers are used to account for the lift and drag characteristics at the low and varying Reynolds conditions encountered in the experiments. The present study focuses on low turbulence inflow conditions and inflow non-uniformity due to wind tunnel characteristics, while higher turbulence conditions are considered in a separate study. The numerical model is validated by using experimental data obtained during test campaigns conducted with the scaled wind farm facility. The simulation and experimental results are compared in terms of power capture, rotor thrust, downstream velocity profiles and turbulence intensity.
Correaltion of full-scale drag predictions with flight measurements on the C-141A aircraft. Phase 2: Wind tunnel test, analysis, and prediction techniques. Volume 1: Drag predictions, wind tunnel data analysis and correlation

NASA Technical Reports Server (NTRS)

Macwilkinson, D. G.; Blackerby, W. T.; Paterson, J. H.

1974-01-01

The degree of cruise drag correlation on the C-141A aircraft is determined between predictions based on wind tunnel test data, and flight test results. An analysis of wind tunnel tests on a 0.0275 scale model at Reynolds number up to 3.05 x 1 million/MAC is reported. Model support interference corrections are evaluated through a series of tests, and fully corrected model data are analyzed to provide details on model component interference factors. It is shown that predicted minimum profile drag for the complete configuration agrees within 0.75% of flight test data, using a wind tunnel extrapolation method based on flat plate skin friction and component shape factors. An alternative method of extrapolation, based on computed profile drag from a subsonic viscous theory, results in a prediction four percent lower than flight test data.
NACA Researcher Sets up a Test of a New Seat Design

NASA Image and Video Library

1954-05-21

A researcher at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory prepares for a test of an NACA-designed aircraft seat. The laboratory had undertaken a multi-year investigation into the causes and prevention of fires on low altitude aircraft crashes. The program was expanded in the mid-1950s to include the study of impact on passengers, types of seat restraints, and seat design. The crash impact portion of the program began by purposely wrecking surplus Fairchild C-82 Packet and Piper Cub aircraft into barricades at the end of a test runway at the Ravenna Arsenal, located approximately 40 miles south of the Lewis lab in Cleveland. Instrumented dummies and cameras were installed in the pilot and passenger areas. After determining the different loads and their effects on the passengers, the NACA researchers began designing new types of seats and restraints. The result was an elastic seat that flexed upon impact, absorbing 75 percent of the loads before it slowly recoiled. This photograph shows the seats mounted on a pendulum with a large spring behind the platform to provide the jolt that mimicked the forces of a crash. The seat was constructed without any potentially damaging metal parts and included rubber-like material, an inflated back and arms, and a seat cushion. After the pendulum tests, the researchers compared the flexible seats to the rigid seats during a crash of a transport aircraft. They found the passengers in the rigid seats received 66 percent higher g-forces than the NACA-designed seats.
Index of NACA Technical Publications: 1915-1949

NASA Technical Reports Server (NTRS)

1949-01-01

The Index of NACA Technical Publications covers reports issued from the date of origin of the Committee in 1915 until approximately September 1949. Because omissions were noted after publication of the Index issued in 1947, and since many new reports have been released since that time, it was decided to issue a new volume to supersede completely the 1947 Index, with supplements to be issued regularly in the future. Commencing with all publications issued after September 1, 1949, subject classifications were revised, the most important change involving the transfer of aircraft loads reports from the Aerodynamics classification to Structures. For those maintaining a file of NACA index cards, it is recommended that cards issued for reports dated prior to September 1, 1949 be removed from the file. This volume includes the same index information. Supplements covering periods following September 1, 1949, will be arranged according to the revised subject classifications. On the pages immediately following, the subject classifications are indexed in order of breakdown. There is included in the back of this volume an alphabetical arrangement of the subject classifications.
HFSB-seeding for large-scale tomographic PIV in wind tunnels

NASA Astrophysics Data System (ADS)

Caridi, Giuseppe Carlo Alp; Ragni, Daniele; Sciacchitano, Andrea; Scarano, Fulvio

2016-12-01

A new system for large-scale tomographic particle image velocimetry in low-speed wind tunnels is presented. The system relies upon the use of sub-millimetre helium-filled soap bubbles as flow tracers, which scatter light with intensity several orders of magnitude higher than micron-sized droplets. With respect to a single bubble generator, the system increases the rate of bubbles emission by means of transient accumulation and rapid release. The governing parameters of the system are identified and discussed, namely the bubbles production rate, the accumulation and release times, the size of the bubble injector and its location with respect to the wind tunnel contraction. The relations between the above parameters, the resulting spatial concentration of tracers and measurement of dynamic spatial range are obtained and discussed. Large-scale experiments are carried out in a large low-speed wind tunnel with 2.85 × 2.85 m2 test section, where a vertical axis wind turbine of 1 m diameter is operated. Time-resolved tomographic PIV measurements are taken over a measurement volume of 40 × 20 × 15 cm3, allowing the quantitative analysis of the tip-vortex structure and dynamical evolution.
Evaluation of wind-induced internal pressure in low-rise buildings: A multi scale experimental and numerical approach

NASA Astrophysics Data System (ADS)

Tecle, Amanuel Sebhatu

Hurricane is one of the most destructive and costly natural hazard to the built environment and its impact on low-rise buildings, particularity, is beyond acceptable. The major objective of this research was to perform a parametric evaluation of internal pressure (IP) for wind-resistant design of low-rise buildings and wind-driven natural ventilation applications. For this purpose, a multi-scale experimental, i.e. full-scale at Wall of Wind (WoW) and small-scale at Boundary Layer Wind Tunnel (BLWT), and a Computational Fluid Dynamics (CFD) approach was adopted. This provided new capability to assess wind pressures realistically on internal volumes ranging from small spaces formed between roof tiles and its deck to attic to room partitions. Effects of sudden breaching, existing dominant openings on building envelopes as well as compartmentalization of building interior on the IP were systematically investigated. Results of this research indicated: (i) for sudden breaching of dominant openings, the transient overshooting response was lower than the subsequent steady state peak IP and internal volume correction for low-wind-speed testing facilities was necessary. For example a building without volume correction experienced a response four times faster and exhibited 30--40% lower mean and peak IP; (ii) for existing openings, vent openings uniformly distributed along the roof alleviated, whereas one sided openings aggravated the IP; (iii) larger dominant openings exhibited a higher IP on the building envelope, and an off-center opening on the wall exhibited (30--40%) higher IP than center located openings; (iv) compartmentalization amplified the intensity of IP and; (v) significant underneath pressure was measured for field tiles, warranting its consideration during net pressure evaluations. The study aimed at wind driven natural ventilation indicated: (i) the IP due to cross ventilation was 1.5 to 2.5 times higher for Ainlet/Aoutlet>1 compared to cases where Ainlet
Analyzing the dynamic response of rotating blades in small-scale wind turbines

NASA Astrophysics Data System (ADS)

Hsiung, Wan-Ying; Huang, Yu-Ting; Loh, Chin-Hsiung; Loh, Kenneth J.; Kamisky, Robert J.; Nip, Danny; van Dam, Cornelis

2014-03-01

The objective of this study was to validate modal analysis, system identification and damage detection of small-scale rotating wind turbine blades in the laboratory and in the field. Here, wind turbine blades were instrumented with accelerometers and strain gages, and data acquisition was achieved using a prototype wireless sensing system. In the first portion of this study conducted in the laboratory, sensors were installed onto metallic structural elements that were fabricated to be representative of an actual wind blade. In order to control the excitation (rotation of the wind blade), a motor was used to spin the blades at controlled angular velocities. The wind turbine was installed on a shaking table for testing under rotation of turbine blades. Data measured by the sensors were recorded while the blade was operated at different speeds. On the other hand, the second part of this study utilized a small-scale wind turbine system mounted on the rooftop of a building. The main difference, as compared to the lab tests, was that the field tests relied on actual wind excitations (as opposed to a controlled motor). The raw data from both tests were analyzed using signal processing and system identification techniques for deriving the model response of the blades. The multivariate singular spectrum analysis (MSSA) and covariance-driven stochastic subspace identification method (SSI-COV) were used to identify the dynamic characteristics of the system. Damage of one turbine blade (loose bolts connection) in the lab test was also conducted. The extracted modal properties for both undamaged and damage cases under different ambient or forced excitations (earthquake loading) were compared. These tests confirmed that dynamic characterization of rotating wind turbines was feasible, and the results will guide future monitoring studies planned for larger-scale systems.
Ramjet Model and Technicians in the 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1952-02-21

A researcher at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory checks the setup of a RJM-2 ramjet model in the test section of the 8- by 6-Foot Supersonic Wind Tunnel. The 8- by 6 was not only the laboratory’s first large supersonic wind tunnel, but it was also the NACA’s first facility capable of testing an operating engine at supersonic speeds. The 8- by 6-foot tunnel has been used to study engine inlets, fuel injectors, flameholders, exit nozzles, and controls on ramjet and turbojet propulsion systems. The 8-foot wide and 6-foot tall test section consisted of 1-inch thick steel plates with hatches on the floor and ceiling to facilitate the installation of the test article. The two windows seen on the right wall allowed photographic equipment to be set up. The test section was modified in 1956 to accommodate transonic research. NACA engineers drilled 4,700 holes into the test section walls to reduce transonic pressure disturbances and shock waves. NACA Lewis undertook an extensive research program on ramjets in the 1940s using several of its facilities. Ramjets provide a very simple source of propulsion. They are basically a tube which ingests high speed air, ignites it, and then expels the heated air at a significantly higher velocity. Ramjets are extremely efficient and powerful but can only operate at high speeds. Therefore, they require a booster rocket or aircraft drop to accelerate them to high speeds before they can operate.
Experimental Studies of Flow Separation of the NACA 2412 Airfoil at Low Speeds

NASA Technical Reports Server (NTRS)

Seetharam, H. C.; Rodgers, E. J.; Wentz, W. H., Jr.

1997-01-01

Wind tunnel tests have been conducted on an NACA 2412 airfoil section at Reynolds number of 2.2 x 10(exp 6) and Mach number of 0.13. Detailed measurements of flow fields associated with turbulent boundary layers have been obtained at angles of attack of 12.4 degrees, 14.4 degrees, and 16.4 degrees. Pre- and post-separated velocity and pressure survey results over the airfoil and in the associated wake are presented. Extensive force, pressure, tuft survey, hot-film survey, local skin friction, and boundary layer data are also included. Pressure distributions and separation point locations show good agreement with theory for the two layer angles of attack. Boundary layer displacement thickness, momentum thickness, and shape factor agree well with theory up to the point of separation. There is considerable disparity between extent of flow reversal in the wake as measured by pressure and hot-film probes. The difference is attributed to the intermittent nature of the flow reversal.
Active flow control for a NACA-0012 Profile: Part II

NASA Astrophysics Data System (ADS)

Oualli, H.; Makadem, M.; Ouchene, H.; Ferfouri, A.; Bouabdallah, A.; Gad-El-Hak, M.

2016-11-01

Active flow control is applied to a NACA-0012 profile. The experiments are conducted in a wind tunnel. Using a high-resolution visible-light camera and tomography, flow visualizations are carried out. LES finite-volume 3D code is used to complement the physical experiments. The symmetric wing is clipped into two parts, and those parts extend and retract along the chord according to the same sinusoidal law we optimized last year for the same profile but clipped at an angle of 60 deg, instead of the original 90 deg. The Reynolds number range is extended to 500,000, thus covering the flying regimes of micro-UAVs, UAVs, as well as small aircraft. When the nascent cavity is open and the attack angle is 30 deg, the drag coefficient is increased by 1,300%, as compared to the uncontrolled case. However, when the cavity is covered and Re <=105 , a relatively small frequency, f <= 30 Hz, is required for the drag coefficient to drop to negative values. At the maximum Reynolds number, thrust is generated but only at much higher frequencies, 12 <= f <= 16 kHz.

Aerodynamic characteristics of the modified 40- by 80-foot wind tunnel as measured in a 1/50th-scale model

NASA Technical Reports Server (NTRS)

Smith, Brian E.; Naumowicz, Tim

1987-01-01

The aerodynamic characteristics of the 40- by 80-Foot Wind Tunnel at Ames Research Center were measured by using a 1/50th-scale facility. The model was configured to closely simulate the features of the full-scale facility when it became operational in 1986. The items measured include the aerodynamic effects due to changes in the total-pressure-loss characteristics of the intake and exhaust openings of the air-exchange system, total-pressure distributions in the flow field at locations around the wind tunnel circuit, the locations of the maximum total-pressure contours, and the aerodynamic changes caused by the installation of the acoustic barrier in the southwest corner of the wind tunnel. The model tests reveal the changes in the aerodynamic performance of the 1986 version of the 40- by 80-Foot Wind Tunnel compared with the performance of the 1982 configuration.
Hydrodynamic and Aerodynamic Tests of a Family of Models of Seaplane Floats with Varying Angles of Dead Rise - N.A.C.A. Models 57-A, 57-B, and 57-C

NASA Technical Reports Server (NTRS)

Parkinson, John B; Olson, Roland E; House, Rufus O

1939-01-01

Three models of V-bottom floats for twin-float seaplanes (N.A.C.A. models 57-A, 57-B, and 57-C) having angles of dead rise of 20 degrees, 25 degrees, and thirty degrees, respectively, were tested in the N.A.C.A. tank and in the N.A.C.A. 7- by 10-foot wind tunnel. Within the range investigated, the effect of angle of dead rise on water resistance was found to be negligible at speeds up to and including the hump speed, and water resistance was found to increase with angle of dead rise at planing speeds. The height of the spray at the hump speed decreased with increase in angle of dead rise and the aerodynamic drag increased with dead rise. Lengthening the forebody of model 57-B decreased the water resistance and the spray at speeds below the hump speed. Spray strips provided an effective means for the control of spray with the straight V sections used in the series but considerably increased the aerodynamic drag. Charts for the determination of the water resistance and the static properties of the model with 25 degrees dead rise and for the aerodynamic drag of all the models are included for use in design.
Full-scale semispan tests of a business-jet wing with a natural laminar flow airfoil

NASA Technical Reports Server (NTRS)

Hahne, David E.; Jordan, Frank L., Jr.

1991-01-01

A full-scale semispan model was investigated to evaluate and document the low-speed, high-lift characteristics of a business-jet class wing that utilized the HSNLF(1)-0213 airfoil section and a single-slotted flap system. Also, boundary-layer transition effects were examined, a segmented leading-edge droop for improved stall/spin resistance was studied, and two roll-controlled devices were evaluated. The wind-tunnel investigation showed that deployment of single-slotted, trailing-edge flap was effective in providing substantial increments in lift required for takeoff and landing performance. Fixed-transition studies to investigate premature tripping of the boundary layer indicated no adverse effects in lift and pitching-moment characteristics for either the cruise or landing configuration. The full-scale results also suggested the need to further optimize the leading-edge droop design that was developed in the subscale tests.
Separating the from the Imagined: Flight Research at the NACA and NASA, 1915-1998

NASA Technical Reports Server (NTRS)

Gorn, Michael H.

2000-01-01

One of the most important, but under-appreciated, aspects of the NACA/NASA mission is its aeronautical R&D efforts. Within a short time of the first flight of the Wright brothers in 1903, the United States government recognized the importance of fostering development in the new and critical field of aeronautics. NASA's predecessor, the National Advisory Committee for Aeronautics (NACA), was chartered by Congress in 1915 specifically "to supervise and direct the scientific study of the problems of flight, with a view to their practical solution. " This became an enormously important government research and development activity for the next half century, materially enhancing the development of aeronautics 'in America. The results of the NACA's research appeared in more than 16,000 research reports of one type or another, distributed widely for the benefit of all. Many of the reports documenting R&D conducted under NACA auspices are still being used today. Since the creation of NASA in 1958, the critical R&D function has continued but is not well known. This work documents the historical R&D program of the agency by focusing on flight research.
Effects of large-scale wind driven turbulence on sound propagation

NASA Technical Reports Server (NTRS)

Noble, John M.; Bass, Henry E.; Raspet, Richard

1990-01-01

Acoustic measurements made in the atmosphere have shown significant fluctuations in amplitude and phase resulting from the interaction with time varying meteorological conditions. The observed variations appear to have short term and long term (1 to 5 minutes) variations at least in the phase of the acoustic signal. One possible way to account for this long term variation is the use of a large scale wind driven turbulence model. From a Fourier analysis of the phase variations, the outer scales for the large scale turbulence is 200 meters and greater, which corresponds to turbulence in the energy-containing subrange. The large scale turbulence is assumed to be elongated longitudinal vortex pairs roughly aligned with the mean wind. Due to the size of the vortex pair compared to the scale of the present experiment, the effect of the vortex pair on the acoustic field can be modeled as the sound speed of the atmosphere varying with time. The model provides results with the same trends and variations in phase observed experimentally.
State Enabling Legislation for Commercial-Scale Wind Power Siting and the Local Government Role

DOE Office of Scientific and Technical Information (OSTI.GOV)

McElfish, J.M.; Gersen, S.

Siting of commercial-scale wind facilities (>5MW) is determined primarily by state laws. State laws either leave siting regulation to local governments, prescribe and constrain the role for local governments, establish state standards, or preempt local governance by having state institutions govern siting. Siting regulation is extremely important to the advancement of wind generation in the United States. Major siting decisions lie ahead for state and local governments as the nation diversifies its energy portfolio. An increase in the number of new wind facilities, siting in more locations and in more heavily populated areas, will require attention to the laws andmore » regulations that govern siting. Local governments exercise some authority over commercial-scale wind facility siting in 48 of the 50 states. In 34 states, local governments have substantial autonomy to regulate the siting of most or all commercial-scale wind facilities. A few states authorize local governments to regulate wind facility siting, but make the scope of local regulation subject to limitations defined by state law. Eleven states set size thresholds for state regulatory involvement with local governments in these states regulating smaller facilities and state boards regulating larger ones (either exclusively or concurrently with local governments). In just under a third of the states, siting of most or all commercial-scale wind facilities requires approval by both state and local government bodies. Only a few states reserve the regulation of siting of all or virtually all commercial-scale wind facilities to state boards and commissions. The content of the applicable regulations is more important, in general, than the level of government responsible for the decision. Several states that assign siting responsibilities to local governments have specified some of the content and the limits of local regulation. About 1/5 of the states have directed boards and commissions to develop statewide
NACA Lewis Researcher and Technicians Discuss a Test Setup

NASA Image and Video Library

1956-12-21

Researcher Bill Reiwaldt discusses the preparations for a test in the Altitude Wind Tunnel with technicians Jack Wagner and Dick Golladay at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. Research engineers developed ideas for tests that were often in response to requests from the military or aircraft industry. Arrangements were made to obtain an engine for the study and to transport it to the Cleveland laboratory. The engine was brought into the facility’s shop area, where it was readied for investigation. It was common for several different engines to be worked on simultaneously in the shop. The researcher would discuss the engine and the test objectives with the Test Installation Division and the facility’s technicians. The operations team would handle the installation of the instrumentation and fitting the test into the facility’s schedule. Upon completion of the previous test, the engine was removed. The next engine was lifted by an overhead crane and transported from the shop to the test section. The engine was connected to the measurement devices and fuel and oil supply lines. Engines were tested over numerous runs under varying conditions and with variations on the configuration. The findings and test procedure were then described in research or technical memorandums and distributed to industry.
5. VIEW NORTH OF TEST SECTION IN FULLSCALE WIND TUNNEL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW NORTH OF TEST SECTION IN FULL-SCALE WIND TUNNEL WITH FREE-FLIGHT MODEL OF A BOEING 737 SUSPENDED FROM A SAFETY CABLE. - NASA Langley Research Center, Full-Scale Wind Tunnel, 224 Hunting Avenue, Hampton, Hampton, VA
High-fidelity numerical simulation of the flow field around a NACA-0012 aerofoil from the laminar separation bubble to a full stall

NASA Astrophysics Data System (ADS)

ElJack, Eltayeb

2017-05-01

In the present work, large eddy simulations of the flow field around a NACA-0012 aerofoil near stall conditions are performed at a Reynolds number of 5 × 104, Mach number of 0.4, and at various angles of attack. The results show the following: at relatively low angles of attack, the bubble is present and intact; at moderate angles of attack, the laminar separation bubble bursts and generates a global low-frequency flow oscillation; and at relatively high angles of attack, the laminar separation bubble becomes an open bubble that leads the aerofoil into a full stall. Time histories of the aerodynamic coefficients showed that the low-frequency oscillation phenomenon and its associated physics are indeed captured in the simulations. The aerodynamic coefficients compared to previous and recent experimental data with acceptable accuracy. Spectral analysis identified a dominant low-frequency mode featuring the periodic separation and reattachment of the flow field. At angles of attack α ≤ 9.3°, the low-frequency mode featured bubble shedding rather than bubble bursting and reformation. The underlying mechanism behind the quasi-periodic self-sustained low-frequency flow oscillation is discussed in detail.
Acoustic Survey of a 3/8-Scale Automotive Wind Tunnel

NASA Technical Reports Server (NTRS)

Booth, Earl R., Jr.; Romberg, Gary; Hansen, Larry; Lutz, Ron

1996-01-01

An acoustic survey that consists of insertion loss and flow noise measurements was conducted at key locations around the circuit of a 3/8-scale automotive acoustic wind tunnel. Descriptions of the test, the instrumentation, and the wind tunnel facility are included in the current report, along with data obtained in the test in the form of 1/3-octave-band insertion loss and narrowband flow noise spectral data.
Orders of Magnitude. A History of the NACA and NASA, 1915-1990. The NASA History Series.

ERIC Educational Resources Information Center

Bilstein, Roger E.

This is a history of the National Advisory Committee for Aeronautics (NACA) and its successor agency the National Aeronautics and Space Administration (NASA). Main chapters included are: (1) "NACA Origins (1915-1930)"; (2) "New Facilities, New Designs (1930-1945)"; (3) "Going Supersonic (1945-1958)"; (4) "On the…
Full-scale Force and Pressure-distribution Tests on a Tapered U.S.A. 45 Airfoil

NASA Technical Reports Server (NTRS)

Parsons, John F

1935-01-01

This report presents the results of force and pressure-distribution tests on a 2:1 tapered USA 45 airfoil as determined in the full-scale wind tunnel. The airfoil has a constant-chord center section and rounded tips and is tapered in thickness from 18 percent at the root to 9 percent at the tip. Force tests were made throughout a Reynolds Number range of approximately 2,000,000 to 8,000,000 providing data on the scale effect in addition to the conventional characteristics. Pressure-distribution data were obtained from tests at a Reynolds Number of approximately 4,000,000. The aerodynamic characteristics given by the usual dimensionless coefficients are presented graphically.
The effects of NACA 0012 airfoil modification on aerodynamic performance improvement and obtaining high lift coefficient and post-stall airfoil

NASA Astrophysics Data System (ADS)

Sogukpinar, Haci

2018-02-01

In this study, aerodynamic performances of NACA 0012 airfoils with distinct modification are numerically investigated to obtain high lift coefficient and post-stall airfoils. NACA 0012 airfoil is divided into two part thought chord line then suction sides kept fixed and by changing the thickness of the pressure side new types of airfoil are created. Numerical experiments are then conducted by varying thickness of NACA 0012 from lower surface and different relative thicknesses asymmetrical airfoils are modified and NACA 0012-10, 0012-08, 0012-07, 0012-06, 0012-04, 0012-03, 0012-02, 0012-01 are created and simulated by using COMSOL software.
Flight Investigation at High Speeds of the Drag of Three Airfoils and a Circular Cylinder Representing Full-Scale Propeller Shanks

NASA Technical Reports Server (NTRS)

Barlow, William H

1946-01-01

Tests have been made at high speeds to determine the drag of models, simulating propeller shanks, in the form of a circular cylinder and three airfoils, the NACA 16-025, the NACA 16-040, and the NACA 16-040 with the rear 25 percent chord cut off. All the models had a maximum thickness of 4 1/2 inches to conform with average propeller-shank dimensions and a span of 20 1/4 inches. For the tests the models were supported perpendicular to the lower surface of the wing of an XP-51 airplane. A wake-survey rake mounted below the wing directly behind the models was used to determine profile drag of Mach numbers of 0.3 to 0.8 over a small range of angle of attack. The drag of the cylinder was also determined from pressure-distribution and force measurements.
Scaling between Wind Tunnels-Results Accuracy in Two-Dimensional Testing

NASA Astrophysics Data System (ADS)

Rasuo, Bosko

The establishment of exact two-dimensional flow conditions in wind tunnels is a very difficult problem. This has been evident for wind tunnels of all types and scales. In this paper, the principal factors that influence the accuracy of two-dimensional wind tunnel test results are analyzed. The influences of the Reynolds number, Mach number and wall interference with reference to solid and flow blockage (blockage of wake) as well as the influence of side-wall boundary layer control are analyzed. Interesting results are brought to light regarding the Reynolds number effects of the test model versus the Reynolds number effects of the facility in subsonic and transonic flow.
Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress.

PubMed

Martin, Raleigh L; Kok, Jasper F

2017-06-01

Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation-the wind-driven transport of sand in hopping trajectories-scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces.
Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress

PubMed Central

Martin, Raleigh L.; Kok, Jasper F.

2017-01-01

Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation—the wind-driven transport of sand in hopping trajectories—scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces. PMID:28630907
Variability in large-scale wind power generation: Variability in large-scale wind power generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiviluoma, Juha; Holttinen, Hannele; Weir, David

2015-10-25

The paper demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability and low net load events. The comparison shows regions with low variability (Sweden, Spain and Germany), medium variability (Portugal, Ireland, Finland and Denmark) and regions with higher variability (Quebec, Bonneville Power Administration and Electric Reliability Council of Texas in North America; Gansu, Jilin and Liaoning in China; and Norway and offshore wind power in Denmark). For regions with low variability, the maximum 1more » h wind ramps are below 10% of nominal capacity, and for regions with high variability, they may be close to 30%. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are autocorrelated and dependent on the operating output level. When wind power was concentrated in smaller area, there were outliers with high changes in wind output, which were not present in large areas with well-dispersed wind power.« less
NACA collections: A directory of significant collections of the documents of the National Advisory Committee for Aeronautics

NASA Technical Reports Server (NTRS)

Smith, Ruth S.

1994-01-01

An alphabetical listing is given of 42 centers that hold National Advisory Committee for Aeronautics (NACA) documents. Information is given on the number of NACA holdings in paper copy, bound volumes, and microfiche. Additional information is given on the bibliographic records and availability.
Dynamic Wind-Tunnel Testing of a Sub-Scale Iced Business Jet

NASA Technical Reports Server (NTRS)

Lee, Sam; Barnhart, Billy P.; Ratvasky, Thomas P.; Dickes, Edward; Thacker, Michael

2006-01-01

The effect of ice accretion on a 1/12-scale complete aircraft model of a business jet was studied in a rotary-balance wind tunnel. Three types of ice accretions were considered: ice protection system failure shape, pre-activation roughness, and runback shapes that form downstream of the thermal ice protection system. The results were compared with those from a 1/12-scale semi-span wing of the same aircraft at similar Reynolds number. The data showed that the full aircraft and the semi-span wing models showed similar characteristics, especially post stall behavior under iced configuration. However, there were also some discrepancies, such as the magnitude in the reductions in the maximum lift coefficient. Most of the ice-induced effects were limited to longitudinal forces. Rotational and forced oscillation studies showed that the effects of ice on lateral forces were relatively minor.

Why Online Education Will Attain Full Scale

ERIC Educational Resources Information Center

Sener, John

2010-01-01

Online higher education has attained scale and is poised to take the next step in its growth. Although significant obstacles to a full scale adoption of online education remain, we will see full scale adoption of online higher education within the next five to ten years. Practically all higher education students will experience online education in…
Measurement of the Critical Distance Parameter Against Icing Conditions on a NACA 0012 Swept Wing Tip

NASA Technical Reports Server (NTRS)

Vargas, Mario; Kreeger, Richard E.

2011-01-01

This work presents the results of three experiments, one conducted in the Icing Research Tunnel (IRT) at NASA Glenn Research Center and two in the Goodrich Icing Wind Tunnel (IWT). The experiments were designed to measure the critical distance parameter on a NACA 0012 Swept Wing Tip at sweep angles of 45deg, 30deg, and 15deg. A time sequence imaging technique (TSIT) was used to obtain real time close-up imaging data during the first 2 min of the ice accretion formation. The time sequence photographic data was used to measure the critical distance at each icing condition and to study how it develops in real time. The effect on the critical distance of liquid water content, drop size, total temperature, and velocity was studied. The results were interpreted using a simple energy balance on a roughness element
Small-scale wind disturbances observed by the MU radar during the passage of typhoon Kelly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Kaoru

1993-02-14

This paper describes small-scale wind disturbances associated with Typhoon Kelly (October 1987) that were observed by the MU radar, one of the MST (mesosphere, stratosphere, and troposphere) radars, for about 60 hours with fine time and height resolution. To elucidate the background of small-scale disturbances, synoptic-scale variation in atmospheric stability related to the typhoon structure during the observation is examined. When the typhoon passed near the MU radar site, the structure was no longer axisymmetric. There is deep convection only in north-northeast side of the typhoon while convection behind it is suppressed by a synoptic-scale cold air mass moving eastwardmore » to the west of the typhoon. A change in atmospheric stability over the radar site as indicated by echo power profiles is likely due to the passage of the sharp transition zone of convection. Strong small-scale wind disturbances were observed around the typhoon passage. The statistical characteristics are different before (BT) and after (AT) the typhoon passage, especially in frequency spectra of vertical wind fluctuations. The spectra for BT are unique compared with earlier studies of vertical winds observed by VHF radars. Another difference is dominance of a horizontal wind component with a vertical wavelength of about 3 km, observed only in AT. Further analyses are made of characteristics and vertical momentum fluxes for dominant disturbances. Some disturbances are generated to remove the momentum of cyclonic wind rotation of the typhoon. Deep convection, topographic effects in strong winds, and strong vertical shear of horizontal winds around an inversion layer are possible sources of the disturbances. Two monochromatic disturbances lasting for more than 10 h in the lower stratosphere observed in BT and AT are identified as inertio-gravity waves, by obtaining wave parameters consistent with all observed quantities. Both of the inertio-gravity waves propagate energy away from the
Modelling utility-scale wind power plants. Part 2: Capacity credit

NASA Astrophysics Data System (ADS)

Milligan, Michael R.

2000-10-01

As the worldwide use of wind turbine generators in utility-scale applications continues to increase, it will become increasingly important to assess the economic and reliability impact of these intermittent resources. Although the utility industry appears to be moving towards a restructured environment, basic economic and reliability issues will continue to be relevant to companies involved with electricity generation. This article is the second in a two-part series that addresses modelling approaches and results that were obtained in several case studies and research projects at the National Renewable Energy Laboratory (NREL). This second article focuses on wind plant capacity credit as measured with power system reliability indices. Reliability-based methods of measuring capacity credit are compared with wind plant capacity factor. The relationship between capacity credit and accurate wind forecasting is also explored. Published in 2000 by John Wiley & Sons, Ltd.
A numerical simulation of the NFAC (National Full-scale Aerodynamics Complex) open-return wind tunnel inlet flow

NASA Technical Reports Server (NTRS)

Kaul, U. K.; Ross, J. C.; Jacocks, J. L.

1985-01-01

The flow into an open return wind tunnel inlet was simulated using Euler equations. An explicit predictor-corrector method was employed to solve the system. The calculation is time-accurate and was performed to achieve a steady-state solution. The predictions are in reasonable agreement with the experimental data. Wall pressures are accurately predicted except in a region of recirculating flow. Flow-field surveys agree qualitatively with laser velocimeter measurements. The method can be used in the design process for open return wind tunnels.
Drive Fan of the NACA's Icing Research Tunnel

NASA Image and Video Library

1956-10-21

A researcher examines the drive fan inside the Icing Research Tunnel at the National Advisory Committee for Aeronautics (NACA) Flight Propulsion Research Laboratory in Cleveland, Ohio. The facility was built in the mid-1940s to simulate the atmospheric conditions that caused ice to build up on aircraft. Carrier Corporation refrigeration equipment reduced the internal air temperature to -45⁰ F, and a spray bar system injected water droplets into the air stream. The 24-foot diameter drive fan, seen in this photograph, created air flow velocities up to 400 miles per hour. The 1950s were prime years for the Icing Research Tunnel. NACA engineers had spent the 1940s trying to resolve the complexities of the spray bar system. The final system put into operation in 1950 included six horizontal spray bars with 80 nozzles that produced a 4- by 4-foot cloud in the test section. The icing tunnel was used for extensive testing of civilian and military aircraft components in the 1950s. The NACA also launched a major investigation of the various methods of heating leading edge surfaces. The hot-air anti-icing technology used on today’s commercial transports was largely developed in the facility during this period. Lewis researchers also made significant breakthroughs with icing on radomes and jet engines. Although the Icing Research Tunnel yielded major breakthroughs in the 1950s, the Lewis icing research program began tapering off as interest in the space program grew. The icing tunnel’s use declined in 1956 and 1957. The launch of Sputnik in October 1957 signaled the end of the facility’s operation. The icing staff was transferred to other research projects and the icing tunnel was temporarily mothballed.
Cooling of Airplane Engines at Low Air Speeds

NASA Technical Reports Server (NTRS)

Theodorsen, Theodore; Brevoort, M J; Stickle, George W

1937-01-01

Report presents the results of a comprehensive experimental study carried out at full scale in the NACA 20-foot wind tunnel, the general purpose of which is to furnish information in regard to the functioning of the power plant and propeller unit under different conditions. This report deals particularly with the problem of the cooling of an airplane engines on the ground. The influence of different nose forms, skirts, flaps, propellers, spinners, and special blowers has been investigated.
Full scale tank car coupler impact tests

DOT National Transportation Integrated Search

2003-11-15

Full scale tests were performed to investigate various : aspects of tank car behavior during coupler impacts. A tank car : was equipped with 37 accelerometers and an instrumented : coupler. Two series of full scale coupler impact tests, : comprising ...
Experimental study on the wind-turbine wake meandering inside a scale model wind farm placed in an atmospheric-boundary-layer wind tunnel

NASA Astrophysics Data System (ADS)

Coudou, N.; Buckingham, S.; van Beeck, J.

2017-05-01

Increasing use of wind energy over the years results in more and larger clustered wind farms. It is therefore fundamental to have an in-depth knowledge of wind-turbine wakes, and especially a better understanding of the well-known but less understood wake-meandering phenomenon which causes the wake to move as a whole in both horizontal and vertical directions as it is convected downstream. This oscillatory motion of the wake is crucial for loading on downstream turbines because it increases fatigue loads and in particular yaw loads. In order to address this phenomenon, experimental investigations were carried out in an atmospheric-boundary-layer wind tunnel using a 3 × 3 scaled wind farm composed of three-bladed rotating wind-turbine models subject to a neutral atmospheric boundary layer (ABL) corresponding to a slightly rough terrain, i.e. to offshore conditions. Particle Image Velocimetry (PIV) measurements were performed in a horizontal plane, at hub height, in the wake of the three wind turbines in the wind-farm centreline. From the PIV velocity fields obtained, the wake-centrelines were determined and a spectral analysis was performed to obtain the characteristics of the wake-meandering phenomenon. In addition, Hot-Wire Anemometry (HWA) measurements were performed in the wakes of the same wind turbines to validate the PIV results. The spectral analysis performed with the spatial and temporal signals obtained from PIV and HWA measurements respectively, led to Strouhal numbers St = fD/Uhub ≃ 0.20 - 0.22.
Tests of a NACA 65(sub 1)-213 airfoil in the NASA Langley 0.3-meter transonic cryogenic tunnel

NASA Technical Reports Server (NTRS)

Plentovich, E. B.; Ladson, C. L.; Hill, A. S.

1984-01-01

A wind-tunnel investigation was conducted to study the two dimensional aerodynamic characteristics of the NACA 65 sub 1-213 airfoil over a wide range of Reynolds numbers. Test temperature ranged from ambient to about 100K at pressures ranging from about 1.2 to 6.0 atm. Mach number was varied from 0.22 to 0.80 and Reynolds number (based on airfoil chord) from 3 million to 40 million. Data are included which demonstrate the effects of fixed transition, Mach number, and Reynolds number on the aerodynamic characteristics of the airfoil. A sample of data showing the effects of angle of attack on the pressure distribution is also given. The data are presented in an uncorrected form with no analysis.
Large-scale solar wind streams: Average temporal evolution of parameters

NASA Astrophysics Data System (ADS)

Yermolaev, Yuri; Lodkina, Irina; Yermolaev, Michael; Nikolaeva, Nadezhda

2016-07-01

In the report we describe the average temporal profiles of plasma and field parameters in the disturbed large-scale types of solar wind (SW): corotating interaction regions (CIR), interplanetary coronal mass ejections (ICME) (both magnetic cloud (MC) and Ejecta), and Sheath as well as the interplanetary shock (IS) on the basis of OMNI database and our Catalog of large-scale solar wind phenomena during 1976-2000 (see website ftp://ftp.iki.rssi.ru/pub/omni/ and paper [Yermolaev et al., 2009]). To consider influence of both the surrounding undisturbed solar wind, and the interaction of the disturbed types of the solar wind on the parameters, we separately analyze the following sequences of the phenomena: (1) SW/CIR/SW, (2) SW/IS/CIR/SW, (3) SW/Ejecta/SW, (4) SW/Sheath/Ejecta/SW, (5) SW/IS/Sheath/Ejecta/SW, (6) SW/MC/SW, (7) SW/Sheath/MC/SW, and (8) SW/IS/Sheath/MC/SW. To take into account the different durations of SW types, we use the double superposed epoch analysis (DSEA) method: rescaling the duration of the interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide [Yermolaev et al., 2010; 2015]. Obtained data allow us to suggest that (1) the behavior of parameters in Sheath and in CIR is very similar not only qualitatively but also quantitatively, and (2) the speed angle phi in ICME changes from 2 to -2deg. while in CIR and Sheath it changes from -2 to 2 deg., i.e., the streams in CIR/Sheath and ICME deviate in the opposite side. The work was supported by the Russian Foundation for Basic Research, project 16-02-00125 and by Program of Presidium of the Russian Academy of Sciences. References: Yermolaev, Yu. I., N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev (2009), Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research, , Vol. 47, No. 2, pp. 81-94. Yermolaev, Y. I., N. S. Nikolaeva, I. G. Lodkina, and M. Y. Yermolaev (2010), Specific interplanetary conditions for CIR
Summary of Full-Scale Blade Displacement Measurements of the UH- 60A Airloads Rotor

NASA Technical Reports Server (NTRS)

Abrego, Anita I.; Meyn, Larry; Burner, Alpheus W.; Barrows, Danny A.

2016-01-01

Blade displacement measurements using multi-camera photogrammetry techniques were acquired for a full-scale UH-60A rotor, tested in the National Full-Scale Aerodynamic Complex 40-Foot by 80-Foot Wind Tunnel. The measurements, acquired over the full rotor azimuth, encompass a range of test conditions that include advance ratios from 0.15 to 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective was to measure the blade displacements and deformations of the four rotor blades and provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft prediction techniques. An overview of the blade displacement measurement methodology, system development, and data analysis techniques are presented. Sample results based on the final set of camera calibrations, data reduction procedures and estimated corrections that account for registration errors due to blade elasticity are shown. Differences in blade root pitch, flap and lag between the previously reported results and the current results are small. However, even small changes in estimated root flap and pitch can lead to significant differences in the blade elasticity values.
Turbulence and entrainment length scales in large wind farms.

PubMed

Andersen, Søren J; Sørensen, Jens N; Mikkelsen, Robert F

2017-04-13

A number of large wind farms are modelled using large eddy simulations to elucidate the entrainment process. A reference simulation without turbines and three farm simulations with different degrees of imposed atmospheric turbulence are presented. The entrainment process is assessed using proper orthogonal decomposition, which is employed to detect the largest and most energetic coherent turbulent structures. The dominant length scales responsible for the entrainment process are shown to grow further into the wind farm, but to be limited in extent by the streamwise turbine spacing, which could be taken into account when developing farm layouts. The self-organized motion or large coherent structures also yield high correlations between the power productions of consecutive turbines, which can be exploited through dynamic farm control.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Author(s).
Turbulence and entrainment length scales in large wind farms

PubMed Central

2017-01-01

A number of large wind farms are modelled using large eddy simulations to elucidate the entrainment process. A reference simulation without turbines and three farm simulations with different degrees of imposed atmospheric turbulence are presented. The entrainment process is assessed using proper orthogonal decomposition, which is employed to detect the largest and most energetic coherent turbulent structures. The dominant length scales responsible for the entrainment process are shown to grow further into the wind farm, but to be limited in extent by the streamwise turbine spacing, which could be taken into account when developing farm layouts. The self-organized motion or large coherent structures also yield high correlations between the power productions of consecutive turbines, which can be exploited through dynamic farm control. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265028
Full-Span Tiltrotor Aeroacoustic Model (TRAM) Overview and 40- by 80-Foot Wind Tunnel Test. [conducted in the 40- by 80-Foot Wind Tunnel at Ames Research Center

NASA Technical Reports Server (NTRS)

McCluer, Megan S.; Johnson, Jeffrey L.; Rutkowski, Michael (Technical Monitor)

2001-01-01

Most helicopter data trends cannot be extrapolated to tiltrotors because blade geometry and aerodynamic behavior, as well as rotor and fuselage interactions, are significantly different for tiltrotors. A tiltrotor model has been developed to investigate the aeromechanics of tiltrotors, to develop a comprehensive database for validating tiltrotor analyses, and to provide a research platform for supporting future tiltrotor designs. The Full-Span Tiltrotor Aeroacoustic Model (FS TRAM) is a dual-rotor, powered aircraft model with extensive instrumentation for measurement of structural and aerodynamic loads. This paper will present the Full-Span TRAM test capabilities and the first set of data obtained during a 40- by 80-Foot Wind Tunnel test conducted in late 2000 at NASA Ames Research Center. The Full-Span TRAM is a quarter-scale representation of the V-22 Osprey aircraft, and a heavily instrumented NASA and U.S. Army wind tunnel test stand. Rotor structural loads are monitored and recorded for safety-of-flight and for information on blade loads and dynamics. Left and right rotor balance and fuselage balance loads are monitored for safety-of-flight and for measurement of vehicle and rotor aerodynamic performance. Static pressure taps on the left wing are used to determine rotor/wing interactional effects and rotor blade dynamic pressures measure blade airloads. All of these measurement capabilities make the FS TRAM test stand a unique and valuable asset for validation of computational codes and to aid in future tiltrotor designs. The Full-Span TRAM was tested in the NASA Ames Research Center 40- by 80-Foot Wind Tunnel from October through December 2000. Rotor and vehicle performance measurements were acquired in addition to wing pressures, rotor acoustics, and Laser Light Sheet (LLS) flow visualization data. Hover, forward flight, and airframe (rotors off) aerodynamic runs were performed. Helicopter-mode data were acquired during angle of attack and thrust sweeps for
General Electric TG-180 Turbojet in the Altitude Wind Tunnel

NASA Image and Video Library

1947-09-21

A General Electric TG-180 turbojet installed in the Altitude Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. In 1943 the military asked General Electric to develop an axial-flow jet engine which became the TG-180. The military understood that the TG-180 would not be ready during World War II but recognized the axial-flow compressor’s long-term potential. Although the engine was bench tested in April 1944, it was not flight tested until February 1946. The TG-180 was brought to the Altitude Wind Tunnel in 1945 for a series of investigations. The studies, which continued intermittently into 1948, analyzed an array of performance issues. NACA modifications steadily improved the TG-180’s performance, including the first successful use of an afterburner. The Lewis researchers studied a 29-inch diameter afterburner over a range of altitude conditions using several different types of flameholders and fuel systems. Lewis researchers concluded that a three-stage flameholder with its largest stage upstream was the best burner configuration. Although the TG-180 (also known as the J35) was not the breakthrough engine that the military had hoped for, it did power the Douglas D-558-I Skystreak to a world speed record on August 20, 1947. The engines were also used on the Republic F-84 Thunderjet and the Northrup F-89 Scorpion.
General Electric TG-100A Turboprop in the Altitude Wind Tunnel

NASA Image and Video Library

1946-12-21

A General Electric TG-100A seen from the rear in the test section of the Altitude Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory in Cleveland, Ohio. The Altitude Wind Tunnel was used to study almost every model of US turbojet that emerged in the 1940s, as well as some ramjets and turboprops. In the early 1940s the military was interested in an engine that would use less fuel than the early jets but would keep up with them performance-wise. Turboprops seemed like a plausible solution. They could move a large volume of air and thus required less engine speed and less fuel. Researchers at General Electric’s plant in Schenectady, New York worked on the turboprop for several years in the 1930s. They received an army contract in 1941 to design a turboprop engine using an axial-flow compressor. The result was the 14-stage TG-100, the nation's first turboprop aircraft engine. Development of the engine was slow, however, and the military asked NACA Lewis to analyze the engine’s performance. The TG-100A was tested in the Altitude Wind Tunnel and it was determined that the compressors, combustion chamber, and turbine were impervious to changes in altitude. The researchers also established the optimal engine speed and propeller angle at simulated altitudes up to 35,000 feet. Despite these findings, development of the TG-100 was cancelled in May 1947. Twenty-eight of the engines were produced, but they were never incorporated into production aircraft.
Environmental aspects of large-scale wind-power systems in the UK

NASA Astrophysics Data System (ADS)

Robson, A.

1984-11-01

Environmental issues relating to the introduction of large, MW-scale wind turbines at land-based sites in the UK are discussed. Noise, television interference, hazards to bird life, and visual effects are considered. Areas of uncertainty are identified, but enough is known from experience elsewhere in the world to enable the first UK machines to be introduced in a safe and environementally acceptable manner. Research to establish siting criteria more clearly, and significantly increase the potential wind-energy resource is mentioned. Studies of the comparative risk of energy systems are shown to be overpessimistic for UK wind turbines.
Convair XF-102 Model in the 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1953-08-21

A .10-scale model of Convair’s XF-102 in the 8- by 6-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory for jet exit studies. The XF-102 was a prototype of the F-102 Delta Dagger. The F-102 served as an interceptor against long range bombers from the Soviet Union. The aircraft was powered by a Pratt and Whitney J57 turbojet. The first prototype crashed two weeks after is first flight on October 24, 1953, just months after this photograph. Engineers then incorporated the fixed-wing design to reduce drag at supersonic speeds. The production model F-102 became the first delta-wing supersonic aircraft in operation. The 8- by 6-Foot Supersonic Wind Tunnel is used to study propulsion systems, including inlets and exit nozzles, combustion fuel injectors, flame holders, exit nozzles, and controls on ramjet and turbojet engines. Flexible sidewalls alter the tunnel’s nozzle shape to vary the Mach number during operation. A seven-stage axial compressor, driven by three electric motors that yield a total of 87,000 horsepower, generates air speeds from Mach 0.36 to 2.0.
Further evaluation of traditional icing scaling methods

NASA Technical Reports Server (NTRS)

Anderson, David N.

1996-01-01

This report provides additional evaluations of two methods to scale icing test conditions; it also describes a hybrid technique for use when scaled conditions are outside the operating envelope of the test facility. The first evaluation is of the Olsen method which can be used to scale the liquid-water content in icing tests, and the second is the AEDC (Ruff) method which is used when the test model is less than full size. Equations for both scaling methods are presented in the paper, and the methods were evaluated by performing icing tests in the NASA Lewis Icing Research Tunnel (IRT). The Olsen method was tested using 53 cm diameter NACA 0012 airfoils. Tests covered liquid-water-contents which varied by as much as a factor of 1.8. The Olsen method was generally effective in giving scale ice shapes which matched the reference shapes for these tests. The AEDC method was tested with NACA 0012 airfoils with chords from 18 cm to 53 cm. The 53 cm chord airfoils were used in reference tests, and 1/2 and 1/3 scale tests were made at conditions determined by applying the AEDC scaling method. The scale and reference airspeeds were matched in these tests. The AEDC method was found to provide fairly effective scaling for 1/2 size tests, but for 1/3 size models, scaling was generally less effective. In addition to these two scaling methods, a hybrid approach was also tested in which the Olsen method was used to adjust the LWC after size was scaled using the constant Weber number method. This approach was found to be an effective way to test when scaled conditions would otherwise be outside the capability of the test facility.

Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction.

PubMed

Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

2016-08-09

Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps.
Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction

PubMed Central

Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C.; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

2016-01-01

Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps. PMID:27457932
Tests of three tapered airfoils based on the N.A.C.A. 2200, the N.A.C.A.-M6, and the Clark Y sections

NASA Technical Reports Server (NTRS)

Anderson, Raymond F

1934-01-01

Three tapered airfoils based on the N.A.C.A. 2200, the N.A.C.A.-M6, and the Clark Y sections were tested in the variable-density wind tunnel at a Reynolds Number of approximately 3,100,000. The models, which were of aspect ratio 6, had constant core center sections and rounded tips, and tapered in thickness from 18 percent at the roots to 9 percent at the tips. The aerodynamic characteristics are given by the usual dimensionless coefficients plotted for both positive and negative angles of attack and by effective profile-drag coefficients plotted against lift coefficients.
Impact of Utility-Scale Distributed Wind on Transmission-Level System Operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brancucci Martinez-Anido, C.; Hodge, B. M.

2014-09-01

This report presents a new renewable integration study that aims to assess the potential for adding distributed wind to the current power system with minimal or no upgrades to the distribution or transmission electricity systems. It investigates the impacts of integrating large amounts of utility-scale distributed wind power on bulk system operations by performing a case study on the power system of the Independent System Operator-New England (ISO-NE).
Final Technical Report Laramie County Community College: Utility-Scale Wind Energy Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Douglas P. Cook

The Utility-Scale Wind Energy Technology U.S. Department of Energy (DOE) grant EE0000538, provided a way ahead for Laramie County Community College (LCCC) to increase educational and training opportunities for students seeking an Associate of Applied Science (AAS) or Associate of Science (AS) degree in Wind Energy Technology. The DOE grant enabled LCCC to program, schedule, and successfully operate multiple wind energy technology cohorts of up to 20-14 students per cohort simultaneously. As of this report, LCCC currently runs four cohorts. In addition, the DOE grant allowed LCCC to procure specialized LABVOLT electronic equipment that directly supports is wind energy technologymore » curriculum.« less
A probabilistic assessment of large scale wind power development for long-term energy resource planning

NASA Astrophysics Data System (ADS)

Kennedy, Scott Warren

A steady decline in the cost of wind turbines and increased experience in their successful operation have brought this technology to the forefront of viable alternatives for large-scale power generation. Methodologies for understanding the costs and benefits of large-scale wind power development, however, are currently limited. In this thesis, a new and widely applicable technique for estimating the social benefit of large-scale wind power production is presented. The social benefit is based upon wind power's energy and capacity services and the avoidance of environmental damages. The approach uses probabilistic modeling techniques to account for the stochastic interaction between wind power availability, electricity demand, and conventional generator dispatch. A method for including the spatial smoothing effect of geographically dispersed wind farms is also introduced. The model has been used to analyze potential offshore wind power development to the south of Long Island, NY. If natural gas combined cycle (NGCC) and integrated gasifier combined cycle (IGCC) are the alternative generation sources, wind power exhibits a negative social benefit due to its high capacity cost and the relatively low emissions of these advanced fossil-fuel technologies. Environmental benefits increase significantly if charges for CO2 emissions are included. Results also reveal a diminishing social benefit as wind power penetration increases. The dependence of wind power benefits on natural gas and coal prices is also discussed. In power systems with a high penetration of wind generated electricity, the intermittent availability of wind power may influence hourly spot prices. A price responsive electricity demand model is introduced that shows a small increase in wind power value when consumers react to hourly spot prices. The effectiveness of this mechanism depends heavily on estimates of the own- and cross-price elasticities of aggregate electricity demand. This work makes a valuable
A STATISTICAL STUDY OF THE SOLAR WIND TURBULENCE AT ION KINETIC SCALES USING THE K-FILTERING TECHNIQUE AND CLUSTER DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, O. W.; Li, X.; Jeska, L., E-mail: o.wyn.roberts@gmail.com, E-mail: xxl@aber.ac.uk

2015-03-20

Plasma turbulence at ion kinetic scales in the solar wind is investigated using the multi-point magnetometer data from the Cluster spacecraft. By applying the k-filtering method, we are able to estimate the full three-dimensional power spectral density P(ω{sub sc}, k) at a certain spacecraft frequency ω{sub sc} in wavevector (k) space. By using the wavevector at the maximum power in P(ω{sub sc}, k) at each sampling frequency ω{sub sc} and the Doppler shifted frequency ω{sub pla} in the solar wind frame, the dispersion plot ω{sub pla} = ω{sub pla}(k) is found. Previous studies have been limited to very few intervalsmore » and have been hampered by large errors, which motivates a statistical study of 52 intervals of solar wind. We find that the turbulence is predominantly highly oblique to the magnetic field k >> k {sub ∥}, and propagates slowly in the plasma frame with most points having frequencies smaller than the proton gyrofrequency ω{sub pla} < Ω{sub p}. Weak agreement is found that turbulence at the ion kinetic scales consists of kinetic Alfvén waves and coherent structures advected with plasma bulk velocity plus some minor more compressible components. The results suggest that anti-sunward and sunward propagating magnetic fluctuations are of similar nature in both the fast and slow solar wind at ion kinetic scales. The fast wind has significantly more anti-sunward flux than sunward flux and the slow wind appears to be more balanced.« less
Surface-pressure Distributions on a Systematic Group of NACA 1-series Cowlings with and Without Spinners

NASA Technical Reports Server (NTRS)

Boswinkle, Robert W JR; Keith, Arvid L JR

1948-01-01

A method for calculating the flow fields of axially symmetric bodies from their pressure distributions is reported in NACA RM No. L8I17. In order to facilitate application of this method to the important case of the cowling-spinner combination, for use in the design of propellers, the present paper presents static-pressure distributions on the tops of 79 high-critical-speed NACA 1-series cowling-spinner combinations over wide ranges of inlet-velocity ratio at angles of attack of 0 degrees, 2 degrees, 4 degrees, and 6 degrees. Static-pressure distributions around the nose sections of several cowlings are given in greater detail to aid in estimating the pressures near the stagnation points and to show the effect of changes in the internal lip shape. The effects of the operation of a typical propeller on the surface pressures on the cowling are shown for one configuration. The pressure distributions over the nine NACA 1-series nose inlets used as the basic components of these combinations are also presented ro supplement the existing open-nose-cowling data of NACA ACR No. L5F30a which are applicable to the case of the rotating cowling.
Strontium Removal: Full-Scale Ohio Demonstrations

EPA Science Inventory

The objectives of this presentation are to present a brief overview of past bench-scale research to evaluate the impact lime softening on strontium removal from drinking water and present full-scale drinking water treatment studies to impact of lime softening and ion exchange sof...
Environmental aspects of large-scale wind-power systems in the UK

NASA Astrophysics Data System (ADS)

Robson, A.

1983-12-01

Environmental issues relating to the introduction of large, MW-scale wind turbines at land-based sites in the U.K. are discussed. Areas of interest include noise, television interference, hazards to bird life and visual effects. A number of areas of uncertainty are identified, but enough is known from experience elsewhere in the world to enable the first U.K. machines to be introduced in a safe and environmentally acceptable manner. Research currently under way will serve to establish siting criteria more clearly, and could significantly increase the potential wind-energy resource. Certain studies of the comparative risk of energy systems are shown to be overpessimistic for U.K. wind turbines.
Development of a wind energy converter with single blade rotor

NASA Astrophysics Data System (ADS)

Hipp, K.

1984-06-01

Wind energy converters with high tip speed ratio and a capacity of up to 50 kW in a 8.5 /msec wind speed were developed. Units with 12 m diameter rotors were tested. The concept of a cost favorable plant as a high speed engine with a supercritically running one blade rotor (soft bearing), gust balance out, automatic blade adjustment to ensure favorable starting qualities, proves to be a success. The single rectangular blade non-twisted with the profile NACA 23012/18 has no dynamic problems. The application of a centrifugal governor, i.e., vane like a Maxwell slat, operating only by rotation about a fixed hinge axis in order to attain adequate constant rotational speed of the plant, is not satisfactory.
NACA Study of Crash Fires with a Fairchild C-82 Packet

NASA Image and Video Library

1950-06-21

Researchers at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory purposely crash a Fairchild C-82 Packet aircraft to study flame propagation. A rash of passenger aircraft crashes in 1946 and 1947 spurred a White House call for an investigatory board staffed by members of the Civil Aeronautics Board, military, and the NACA. The group addressed fire segregation, extinguishment, and prevention. The NACA established a Subcommittee on Aircraft Fire Prevention in February 1948 to coordinate its efforts. The Lewis team simulated situations in which an aircraft failed to become airborne during takeoff resulting in crashes into embankments and other objects. The Lewis researchers initially used surplus C-46 and C-82 military transport planes. In these situations, the aircraft generally suffered damage to its fuel system and other components, but was structurally survivable. The aircraft were mounted to a rail that ran down a 1700-foot long test runway. The aircraft was secured at the starting point with an anchor pier so it could get its engines up to takeoff speed before launching down the track. Barriers at the end of the runway were designed to simulate a variety of different types of crashes. Telemetry and high-speed cameras were crucial elements in these studies. The preliminary testing phase identified potential ignition sources and analyzed the spread of flammable materials.
Education, Wechler's Full Scale IQ and "g."

ERIC Educational Resources Information Center

Colom, Roberto; Abad, Francisco J.; Garcia, Luis F.; Juan-Espinosa, Manuel

2002-01-01

Investigated whether average Full Scale IQ (FSIQ) differences can be attributed to "g" using the Spanish standardization sample of the Wechsler Adult Intelligence Scale III (WAIS III) (n=703 females and 666 men). Results support the conclusion that WAIS III FSIQ does not directly or exclusively measure "g" across the full range…
Large scale wind tunnel investigation of a folding tilt rotor

NASA Technical Reports Server (NTRS)

1972-01-01

A twenty-five foot diameter folding tilt rotor was tested in a large scale wind tunnel to determine its aerodynamic characteristics in unfolded, partially folded, and fully folded configurations. During the tests, the rotor completed over forty start/stop sequences. After completing the sequences in a stepwise manner, smooth start/stop transitions were made in approximately two seconds. Wind tunnel speeds up through seventy-five knots were used, at which point the rotor mast angle was increased to four degrees, corresponding to a maneuver condition of one and one-half g.
Wind-Tunnel Investigation of a Full-Scale Canard-Configured General Aviation Airplane

NASA Technical Reports Server (NTRS)

Yip, L. P.

1985-01-01

An investigation was conducted in the Langley 30- by 60-Foot Tunnel to determine the aerodynamic characteristics of a powered, full-scale model of a general aviation airplane employing a canard. Although primary emphasis of the investigation was placed on evaluating the aerodynamic performance and the stability and control characteristics of the basic configuration, tests were also conducted to study the following effects of varying the basic configuration: effect of Reynolds number; effect of canard; effect of outboard wing leading-edge droop; effect of center-of-gravity location; effect of elevator trim; effect of landing gear; effect of lateral-directional control; effect of power; effect of fixed transition; effect of water spray; effects of canard incidence, canard airfoil section, and canard position; and effects of winglets and upper winglet size. Additional aspects of the study were to determine the boundary-layer transition characteristics of airfoil surfaces and the effect of fixing the boundary layer to be turbulent by means of a transition strip near the leading edge. The tests were conducted at Reynolds numbers from 0.60 x 10 to the 6th power to 2.25x10 to the 6th power, based on the wing mean aerodynamic chord, at angles of attack from -4.5 deg to 41.5 deg, and at angles of sideslip from -15 deg to 15 deg.
Solar Wind Turbulence from MHD to Sub-ion Scales: High-resolution Hybrid Simulations

NASA Astrophysics Data System (ADS)

Franci, Luca; Verdini, Andrea; Matteini, Lorenzo; Landi, Simone; Hellinger, Petr

2015-05-01

We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wavenumbers. The simulation results simultaneously exhibit several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magnetohydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and the parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind, large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm’s law.
3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges

NASA Astrophysics Data System (ADS)

Mikkelsen, T.; Sjöholm, M.; Angelou, N.; Mann, J.

2017-12-01

WindScanner is a distributed research infrastructure developed at DTU with the participation of a number of European countries. The research infrastructure consists of a mobile technically advanced facility for remote measurement of wind and turbulence in 3D. The WindScanners provide coordinated measurements of the entire wind and turbulence fields, of all three wind components scanned in 3D space. Although primarily developed for research related to on- and offshore wind turbines and wind farms, the facility is also well suited for scanning turbulent wind fields around buildings, bridges, aviation structures and of flow in urban environments. The mobile WindScanner facility enables 3D scanning of wind and turbulence fields in full scale within the atmospheric boundary layer at ranges from 10 meters to 5 (10) kilometers. Measurements of turbulent coherent structures are applied for investigation of flow pattern and dynamical loads from turbines, building structures and bridges and in relation to optimization of the location of, for example, wind farms and suspension bridges. This paper presents our achievements to date and reviews briefly the state-of-the-art of the WindScanner measurement technology with examples of uses for wind engineering applications.
Electric power from offshore wind via synoptic-scale interconnection

PubMed Central

Kempton, Willett; Pimenta, Felipe M.; Veron, Dana E.; Colle, Brian A.

2010-01-01

World wind power resources are abundant, but their utilization could be limited because wind fluctuates rather than providing steady power. We hypothesize that wind power output could be stabilized if wind generators were located in a meteorologically designed configuration and electrically connected. Based on 5 yr of wind data from 11 meteorological stations, distributed over a 2,500 km extent along the U.S. East Coast, power output for each hour at each site is calculated. Each individual wind power generation site exhibits the expected power ups and downs. But when we simulate a power line connecting them, called here the Atlantic Transmission Grid, the output from the entire set of generators rarely reaches either low or full power, and power changes slowly. Notably, during the 5-yr study period, the amount of power shifted up and down but never stopped. This finding is explained by examining in detail the high and low output periods, using reanalysis data to show the weather phenomena responsible for steady production and for the occasional periods of low power. We conclude with suggested institutions appropriate to create and manage the power system analyzed here. PMID:20368464
Wind-Tunnel Tests of the 1/25-Scale Powered Model of the Martin JRM-1 Airplane. IV - Tests with Ground Board and with Modified Wing and Hull - TED No. NACA 232. Part 4; Tests with Ground Board and with Modified Wing and Hull, TED No. NACA 232

NASA Technical Reports Server (NTRS)

Lockwood, Vernard E.; Smith, Bernard J.

1947-01-01

Wind-tunnel tests were made of a 1/25 scale model of the Martin JRM-1 airplane to determine: (1) The longitudinal stability and control characteristics of the JRM-1 model near the water and lateral and directional stability characteristics with power while moving on the surface of the water, the latter being useful for the design of tip floats; (2) The stability and stalling characteristics of the wing with a modified airfoil contour; (3) Stability characteristics of a hull of larger design gross weight; The test results indicated that the elevator was powerful enough to trim the original model in a landing configuration at any lift coefficient within the specified range of centers of gravity. The ground-board tests for evaluating the aerodynamic forces and moments on an airplane in a simulated cross wind indicate a high dihedral effect in the presence of the ground board and, consequently, during low-speed taxying and take-off, large overturning moments would result which would have to be overcome by the tip floats.
NACA Conference on Turbojet-Engine Thrust Augmentation Research: A Compilation of the Papers Presented by NACA Staff Members

NASA Technical Reports Server (NTRS)

1948-01-01

The conference on Turbojet-Engine Thrust-Augmentation Research was organized by the NACA to present in summarized form the results of the latest experimental and analytical investigations conducted at the Lewis Flight Propulsion Laboratory on methods of augmenting the thrust of turbojet engines. The technical discussions are reproduced herewith in the same form in which they were presented. The original presentation in this record are considered as complementary to, rather than substitutes for, the committee's system of complete and formal reports.

Multifractal Analysis of the Small Time-Scale Boundary-Layer Characteristics of the Wind: the Anisotropy and Extremes

NASA Astrophysics Data System (ADS)

Fitton, G. F.; Tchiguirinskaia, I.; Schertzer, D. J.; Lovejoy, S.

2012-12-01

Under various physical conditions (mean temperature and velocity gradients, stratification and rotation) atmospheric turbulent flows remain intrinsically anisotropic. The immediate vicinity of physical boundaries rises to a greater complexity of the anisotropy effects. In this paper we address the issue of the scaling anisotropy of the wind velocity fields within the atmospheric boundary layer (ABL). Under the universal multifractal (UM) framework we compare the small time-scale (0.1 to 1,000 seconds) boundary-layer characteristics of the wind for two different case studies. The first case study consisted of a single mast located within a wind farm in Corsica, France. Three sonic anemometers were installed on the mast at 22, 23 and 43m, measuring three-dimensional wind velocity data at 10Hz. Wakes, complex terrain and buoyancy forces influenced the measurements. The second case study (GROWIAN experiment in Germany) consisted of an array of propeller anemometers measuring wind speed inflow data at 2.5Hz over flat terrain. The propeller anemometers were positioned vertically at 10, 50, 75, 100, 125 and 150m with four horizontal measurements taken at 75, 100 and 125m. The spatial distribution allowed us to calculate the horizontal and vertical shear structure functions of the horizontal wind. Both case studies are within a kilometre from the sea. For the first case study (10Hz measurements in a wind farm test site) the high temporal resolution of the data meant we observed Kolmogorov scaling from 0.2 seconds (with intermittency correction) right up to 1,000 seconds at which point a scaling break occurred. After the break we observed a scaling power law of approximately 2, which is in agreement with Bolgiano-Obukhov scaling theory with intermittency correction. However, for the second case study (2.5Hz on flat terrain) we only observed Kolmogorov scaling from 6.4 seconds (also with intermittency correction). The spectra of horizontal velocity components remain
Spectral scaling laws of solar wind fluctuations at 1 AU: Part 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podesta, John J.

2013-06-13

In-situ measurements of solar wind fluctuations at 1 AU show that the reduced energy spectrum, equal to the sum of the reduced kinetic plus magnetic energy spectra, is characterized by a power-law scaling k{sup -{alpha}} in the inertial range with an average spectral exponent {alpha} Asymptotically-Equal-To 3/2, a result confirmed by independent analyses using data from different spacecraft. Magnetic field and electron density spectra at kinetic scales {rho}{sup -1}{sub i} < k < {rho}{sup -1}{sub e} both have a spectral index of approximately 2.7. These and other recent observations of spectral scaling laws in the solar wind using single spacecraftmore » measurements are briefly reviewed. The first part of this review, Part 1, is contained in a separate paper in these proceedings.« less
Impact Test of a NACA-Designed Pilot Seat and Harness

NASA Image and Video Library

1955-02-21

This time-lapse photograph shows the test of a pilot seat and restraint designed by researchers at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The laboratory had undertaken a multi-year investigation into the causes and preventative measures for fires resulting from low altitude aircraft crashes. The program was expanded in the mid-1950s to include the study of crash impact on passengers, new types of types of seat restraints, and better seat designs. The impact program began by purposely wrecking surplus transport Fairchild C-82 Packet and Piper Cub aircraft into barricades at the end of a test runway. Instrumented dummies and cameras were installed in the pilot and passenger areas. After determining the different loads experienced during a crash and the effects on the passengers, the NACA researchers began designing new types of seats and restraints. The result was an elastic seat that flexed upon impact, absorbing 75 percent of the loads before it slowly recoiled. This photograph shows the seats mounted on a pendulum with a large spring behind the platform to provide the jolt that mimicked the forces of a crash. The seat was constructed without any potentially damaging metal parts and included rubber-like material, an inflated back and arms, and a seat cushion. After the pendulum tests, the researchers compared the flexible seats to the rigid seats during a crash of a transport aircraft. They found the passengers in the rigid seats received 66 percent higher g-forces than the NACA-designed seats.
Active Flow Control at Low Reynolds Numbers on a NACA 0015 Airfoil

NASA Technical Reports Server (NTRS)

Melton, LaTunia Pack; Hannon, Judith; Yao, Chung-Sheng; Harris, Jerome

2008-01-01

Results from a low Reynolds number wind tunnel experiment on a NACA 0015 airfoil with a 30% chord trailing edge flap tested at deflection angles of 0, 20, and 40 are presented and discussed. Zero net mass flux periodic excitation was applied at the ap shoulder to control flow separation for flap deflections larger than 0. The primary objective of the experiment was to compare force and moment data obtained from integrating surface pressures to data obtained from a 5-component strain-gage balance in preparation for additional three-dimensional testing of the model. To achieve this objective, active flow control is applied at an angle of attack of 6 where published results indicate that oscillatory momentum coefficients exceeding 1% are required to delay separation. Periodic excitation with an oscillatory momentum coefficient of 1.5% and a reduced frequency of 0.71 caused a significant delay of separation on the airfoil with a flap deflection of 20. Higher momentum coefficients at the same reduced frequency were required to achieve a similar level of flow attachment on the airfoil with a flap deflection of 40. There was a favorable comparison between the balance and integrated pressure force and moment results.
An Experimental Investigation of Flow Conditions in the Vicinity of an NACA D(sub S)-type Cowling

NASA Technical Reports Server (NTRS)

Bryant, Rosemary P.; Boswinkle, Robert W.

1946-01-01

Data are presented of the flow conditions in the vicinity of an NACA D sub S -type cowling. Tests were made of a 1/2 scale-nacelle model at inlet-velocity ratios ranging from 0.23 to 1.02 and angles of attack from 6 deg to 10 deg. The velocity and direction of flow in the vertical plane of symmetry of the cowling were determined from orifices and tufts installed on a board aligned with the flow. Diagrams showing velocity ratio contours and lines of constant flow angles are given.
Design, manufacturing and characterization of aero-elastically scaled wind turbine blades for testing active and passive load alleviation techniques within a ABL wind tunnel

NASA Astrophysics Data System (ADS)

Campagnolo, Filippo; Bottasso, Carlo L.; Bettini, Paolo

2014-06-01

In the research described in this paper, a scaled wind turbine model featuring individual pitch control (IPC) capabilities, and equipped with aero-elastically scaled blades featuring passive load reduction capabilities (bend-twist coupling, BTC), was constructed to investigate, by means of wind tunnel testing, the load alleviation potential of BTC and its synergy with active load reduction techniques. The paper mainly focus on the design of the aero-elastic blades and their dynamic and static structural characterization. The experimental results highlight that manufactured blades show desired bend-twist coupling behavior and are a first milestone toward their testing in the wind tunnel.
77 FR 14342 - Utility Scale Wind Towers From the People's Republic of China: Notice of Postponement of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-09

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-982] Utility Scale Wind Towers... 202-482-1503, respectively. SUPPLEMENTARY INFORMATION: Background On January 18, 2012, the Department of Commerce (the Department) initiated the countervailing duty investigation of utility scale wind...
Some techniques for reducing the tower shadow of the DOE/NASA mod-0 wind turbine tower. [wind tunnel tests to measure effects of tower structure on wind velocity

NASA Technical Reports Server (NTRS)

Burley, R. R.; Savino, J. M.; Wagner, L. H.; Diedrich, J. H.

1979-01-01

Wind speed profile measurements to measure the effect of a wind turbine tower on the wind velocity are presented. Measurements were made in the wake of scale models of the tower and in the wake of certain full scale components to determine the magnitude of the speed reduction (tower shadow). Shadow abatement techniques tested on the towers included the removal of diagonals, replacement of diagonals and horizontals with round cross section members, installation of elliptical shapes on horizontal members, installation of airfoils on vertical members, and application of surface roughness to vertical members.
SOLAR WIND TURBULENCE FROM MHD TO SUB-ION SCALES: HIGH-RESOLUTION HYBRID SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franci, Luca; Verdini, Andrea; Landi, Simone

2015-05-10

We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wavenumbers. The simulation results simultaneously exhibit several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magnetohydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and themore » parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind, large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm’s law.« less
Evaluation of Scaling Methods for Rotorcraft Icing

NASA Technical Reports Server (NTRS)

Tsao, Jen-Ching; Kreeger, Richard E.

2010-01-01

This paper reports result of an experimental study in the NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the current recommended scaling methods developed for fixed-wing unprotected surface icing applications might apply to representative rotor blades at finite angle of attack. Unlike the fixed-wing case, there is no single scaling method that has been systematically developed and evaluated for rotorcraft icing applications. In the present study, scaling was based on the modified Ruff method with scale velocity determined by maintaining constant Weber number. Models were unswept NACA 0012 wing sections. The reference model had a chord of 91.4 cm and scale model had a chord of 35.6 cm. Reference tests were conducted with velocities of 76 and 100 kt (39 and 52 m/s), droplet MVDs of 150 and 195 fun, and with stagnation-point freezing fractions of 0.3 and 0.5 at angle of attack of 0deg and 5deg. It was shown that good ice shape scaling was achieved for NACA 0012 airfoils with angle of attack lip to 5deg.
Full scale wind turbine test of vortex generators mounted on the entire blade

NASA Astrophysics Data System (ADS)

Bak, Christian; Skrzypiński, Witold; Gaunaa, Mac; Villanueva, Hector; Brønnum, Niels F.; Kruse, Emil K.

2016-09-01

Measurements on a heavily instrumented pitch regulated variable speed Vestas V52 850 kW wind turbine situated at the DTU Risø Campus are carried out, where the effect of vortex generators mounted on almost the entire blade is tested with and without leading edge roughness. The measurements are compared to the predictions carried out by a developed design tool, where the effect of vortex generators and leading edge roughness is simulated using engineering models. The measurements showed that if vortex generators are mounted there is an increase in flapwise blade moments if the blades are clean, but also that the loads are almost neutral when vortex generators are installed if there is leading edge roughness on the blades. Finally, it was shown that there was a good agreement between the measurements and the predictions from the design tool.
Modelling utility-scale wind power plants. Part 1: Economics

NASA Astrophysics Data System (ADS)

Milligan, Michael R.

1999-10-01

As the worldwide use of wind turbine generators continues to increase in utility-scale applications, it will become increasingly important to assess the economic and reliability impact of these intermittent resources. Although the utility industry in the United States appears to be moving towards a restructured environment, basic economic and reliability issues will continue to be relevant to companies involved with electricity generation. This article is the first of two which address modelling approaches and results obtained in several case studies and research projects at the National Renewable Energy Laboratory (NREL). This first article addresses the basic economic issues associated with electricity production from several generators that include large-scale wind power plants. An important part of this discussion is the role of unit commitment and economic dispatch in production cost models. This paper includes overviews and comparisons of the prevalent production cost modelling methods, including several case studies applied to a variety of electric utilities. The second article discusses various methods of assessing capacity credit and results from several reliability-based studies performed at NREL.
Stereo particle image velocimetry set up for measurements in the wake of scaled wind turbines

NASA Astrophysics Data System (ADS)

Campanardi, Gabriele; Grassi, Donato; Zanotti, Alex; Nanos, Emmanouil M.; Campagnolo, Filippo; Croce, Alessandro; Bottasso, Carlo L.

2017-08-01

Stereo particle image velocimetry measurements were carried out in the boundary layer test section of Politecnico di Milano large wind tunnel to survey the wake of a scaled wind turbine model designed and developed by Technische Universität München. The stereo PIV instrumentation was set up to survey the three velocity components on cross-flow planes at different longitudinal locations. The area of investigation covered the entire extent of the wind turbines wake that was scanned by the use of two separate traversing systems for both the laser and the cameras. Such instrumentation set up enabled to gain rapidly high quality results suitable to characterise the behaviour of the flow field in the wake of the scaled wind turbine. This would be very useful for the evaluation of the performance of wind farm control methodologies based on wake redirection and for the validation of CFD tools.
A full-scale wind tunnel investigation of a helicopter bearingless main rotor. [Ames 40 by 80 Wind Tunnel

NASA Technical Reports Server (NTRS)

Warmbrodt, W.; Mccloud, J. L., II

1981-01-01

A helicopter bearingless main rotor was tested. Areas of investigation included aeroelastic stability, aerodynamic performance, and rotor loads as a function of collective pitch setting, RPM, airspeed and shaft angle. The rotor/support system was tested with the wind tunnel balance dampers installed and, subsequently, removed. Modifications to the rotor hub were tested. These included a reduction in the rotor control system stiffness and increased flexbeam structural damping. The primary objective of the test was to determine aeroelastic stability of the fundamental flexbeam/blade chordwise bending mode. The rotor was stable for all conditions. Damping of the rotor chordwise bending mode increases with increased collective pitch angle at constant operating conditions. No significant decrease in rotor damping occured due to frequency coalescence between the blade chordwise fundamental bending mode and the support system.
Construction of the Propulsion Systems Laboratory No. 1 and 2

NASA Image and Video Library

1951-01-21

Construction of the Propulsion Systems Laboratory No. 1 and 2 at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. When it began operation in late 1952, the Propulsion Systems Laboratory was the NACA’s most powerful facility for testing full-scale engines at simulated flight altitudes. The facility contained two altitude simulating test chambers which were a technological combination of the static sea-level test stands and the complex Altitude Wind Tunnel, which recreated actual flight conditions on a larger scale. NACA Lewis began designing the new facility in 1947 as part of a comprehensive plan to improve the altitude testing capabilities across the lab. The exhaust, refrigeration, and combustion air systems from all the major test facilities were linked. In this way, different facilities could be used to complement the capabilities of one another. Propulsion Systems Laboratory construction began in late summer 1949 with the installation of an overhead exhaust pipe connecting the facility to the Altitude Wind Tunnel and Engine Research Building. The large test section pieces arriving in early 1951, when this photograph was taken. The two primary coolers for the altitude exhaust are in place within the framework near the center of the photograph.
Computational investigation of flow control by means of tubercles on Darrieus wind turbine blades

NASA Astrophysics Data System (ADS)

Sevinç, K.; Özdamar, G.; Şentürk, U.; Özdamar, A.

2015-09-01

This work presents the current status of the computational study of the boundary layer control of a vertical axis wind turbine blade by modifying the blade geometry for use in wind energy conversion. The control method is a passive method which comprises the implementation of the tubercle geometry of a humpback whale flipper onto the leading edge of the blades. The baseline design is an H-type, three-bladed Darrieus turbine with a NACA 0015 cross-section. Finite-volume based software ANSYS Fluent was used in the simulations. Using the optimum control parameters for a NACA 634-021 profile given by Johari et al. (2006), turbine blades were modified. Three dimensional, unsteady, turbulent simulations for the blade were conducted to look for a possible improvement on the performance. The flow structure on the blades was investigated and flow phenomena such as separation and stall were examined to understand their impact on the overall performance. For a tip speed ratio of 2.12, good agreement was obtained in the validation of the baseline model with a relative error in time- averaged power coefficient of 1.05%. Modified turbine simulations with a less expensive but less accurate turbulence model yielded a decrease in power coefficient. Results are shown comparatively.
A study of rotor and platform design trade-offs for large-scale floating vertical axis wind turbines

NASA Astrophysics Data System (ADS)

Griffith, D. Todd; Paquette, Joshua; Barone, Matthew; Goupee, Andrew J.; Fowler, Matthew J.; Bull, Diana; Owens, Brian

2016-09-01

Vertical axis wind turbines are receiving significant attention for offshore siting. In general, offshore wind offers proximity to large populations centers, a vast & more consistent wind resource, and a scale-up opportunity, to name a few beneficial characteristics. On the other hand, offshore wind suffers from high levelized cost of energy (LCOE) and in particular high balance of system (BoS) costs owing to accessibility challenges and limited project experience. To address these challenges associated with offshore wind, Sandia National Laboratories is researching large-scale (MW class) offshore floating vertical axis wind turbines (VAWTs). The motivation for this work is that floating VAWTs are a potential transformative technology solution to reduce offshore wind LCOE in deep-water locations. This paper explores performance and cost trade-offs within the design space for floating VAWTs between the configurations for the rotor and platform.
48 CFR 34.005-5 - Full-scale development contracts.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Full-scale development... SPECIAL CATEGORIES OF CONTRACTING MAJOR SYSTEM ACQUISITION General 34.005-5 Full-scale development contracts. Whenever practicable, the full-scale development contracts should provide for the contractors to...
48 CFR 34.005-5 - Full-scale development contracts.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Full-scale development... SPECIAL CATEGORIES OF CONTRACTING MAJOR SYSTEM ACQUISITION General 34.005-5 Full-scale development contracts. Whenever practicable, the full-scale development contracts should provide for the contractors to...
Large Scale Winter Time Disturbances in Meteor Winds over Central and Eastern Europe

NASA Technical Reports Server (NTRS)

Greisiger, K. M.; Portnyagin, Y. I.; Lysenko, I. A.

1984-01-01

Daily zonal wind data of the four pre-MAP-winters 1978/79 to 1981/82 obtained over Central Europe and Eastern Europe by the radar meteor method were studied. Available temperature and satellite radiance data of the middle and upper stratosphere were used for comparison, as well as wind data from Canada. The existence or nonexistence of coupling between the observed large scale zonal wind disturbances in the upper mesopause region (90 to 100 km) and corresponding events in the stratosphere are discussed.

The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel

NASA Technical Reports Server (NTRS)

Jacobs, Eastman N; Ward, Kenneth E; Pinkerton, Robert M

1933-01-01

An investigation of a large group of related airfoils was made in the NACA variable-density wind tunnel at a large value of the Reynolds number. The tests were made to provide data that may be directly employed for a rational choice of the most suitable airfoil section for a given application. The variation of the aerodynamic characteristics with variations in thickness and mean-line form were systematically studied. (author)
Direct Numerical Simulations of a Full Stationary Wind-Turbine Blade

NASA Astrophysics Data System (ADS)

Qamar, Adnan; Zhang, Wei; Gao, Wei; Samtaney, Ravi

2014-11-01

Direct numerical simulation of flow past a full stationary wind-turbine blade is carried out at Reynolds number, Re = 10,000 placed at 0 and 5 (degree) angle of attack. The study is targeted to create a DNS database for verification of solvers and turbulent models that are utilized in wind-turbine modeling applications. The full blade comprises of a circular cylinder base that is attached to a spanwise varying airfoil cross-section profile (without twist). An overlapping composite grid technique is utilized to perform these DNS computations, which permits block structure in the mapped computational space. Different flow shedding regimes are observed along the blade length. Von-Karman shedding is observed in the cylinder shaft region of the turbine blade. Along the airfoil cross-section of the blade, near body shear layer breakdown is observed. A long tip vortex originates from the blade tip region, which exits the computational plane without being perturbed. Laminar to turbulent flow transition is observed along the blade length. The turbulent fluctuations amplitude decreases along the blade length and the flow remains laminar regime in the vicinity of the blade tip. The Strouhal number is found to decrease monotonously along the blade length. Average lift and drag coefficients are also reported for the cases investigated. Supported by funding under a KAUST OCRF-CRG grant.
An experimental study of the aerodynamics of a NACA 0012 airfoil with a simulated glaze ice accretion

NASA Technical Reports Server (NTRS)

Bragg, M. B.

1986-01-01

An experimental study was conducted in the Ohio State University subsonic wind tunnel to measure the detailed aerodynamic characteristics of an airfoil with a simulated glaze ice accretion. A NACA 0012 model with interchangeable leading edges and pressure taps every one percent chord was used. Surface pressure and wake data were taken on the airfoil clean, with forced transition and with a simulated glaze ice shape. Lift and drag penalties due to the ice shape were found and the surface pressure clearly showed that large separation bubbles were present. Both total pressure and split-film probes were used to measure velocity profiles, both for the clean model and for the model with a simulated ice accretion. A large region of flow separation was seen in the velocity profiles and was correlated to the pressure measurements. Clean airfoil data were found to compare well to existing airfoil analysis methods.
Pressure measurements on a rectangular wing with a NACA0012 airfoil during conventional flutter

NASA Technical Reports Server (NTRS)

Rivera, Jose A., Jr.; Dansberry, Bryan E.; Durham, Michael H.; Bennett, Robert M.; Silva, Walter A.

1992-01-01

The Structural Dynamics Division at NASA LaRC has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of the program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type CFD codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. The first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree-of-freedom mount system. Two wind-tunnel tests were conducted with the first model. Several dynamic instability boundaries were investigated such as a conventional flutter boundary, a transonic plunge instability region near Mach = 0.90, and stall flutter. In addition, wing surface unsteady pressure data were acquired along two model chords located at the 60 to 95-percent span stations during these instabilities. At this time, only the pressure data for the conventional flutter boundary is presented. The conventional flutter boundary and the wing surface unsteady pressure measurements obtained at the conventional flutter boundary test conditions in pressure coefficient form are presented. Wing surface steady pressure measurements obtained with the model mount system rigidized are also presented. These steady pressure data were acquired at essentially the same dynamic pressure at which conventional flutter had been encountered with the mount system flexible.
Integrating Systems Health Management with Adaptive Controls for a Utility-Scale Wind Turbine

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Goebel, Kai; Trinh, Khanh V.; Balas, Mark J.; Frost, Alan M.

2011-01-01

Increasing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. Systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage. Advanced adaptive controls can provide the mechanism to enable optimized operations that also provide the enabling technology for Systems Health Management goals. The work reported herein explores the integration of condition monitoring of wind turbine blades with contingency management and adaptive controls. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine.
High-speed imaging of the transient ice accretion process on a NACA 0012 airfoil

NASA Astrophysics Data System (ADS)

Waldman, Rye; Hu, Hui

2014-11-01

Ice accretion on aircraft wings poses a performance and safety threat as aircraft encounter supercooled droplets suspended in the cloud layer. The details of the ice accretion depend on the atmospheric conditions and the fight parameters. We present the measurement results of the experiments conducted in the Iowa State icing wind tunnel on a NACA 0012 airfoil to study the transient ice accretion process under varying icing conditions. The icing process on the wing consists of a complex interaction of water deposition, surface water transport, and freezing. The aerodynamics affects the water deposition, the heat and mass transport, and ice accumulation; meanwhile, the accumulating ice also affects the aerodynamics. High-speed video of the unsteady icing accretion process was acquired under controlled environmental conditions to quantitatively measure the transient water run back, rivulet formation, and accumulated ice growth, and the experiments show how varying the environmental conditions modifies the ice accretion process. Funding support from the Iowa Energy Center with Grant No. 14-008-OG and National Science Foundation (NSF) with Grant No. CBET-1064196 and CBET-1438099 is gratefully acknowledged.
77 FR 29315 - Utility Scale Wind Towers From the People's Republic of China and the Socialist Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-17

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-981, A-552-814] Utility Scale... duty investigations of utility scale wind towers from the People's Republic of China and the Socialist... investigations are currently due no later than June 6, 2012. \\1\\ See Utility Scale Wind Towers From the People's...
Aerodynamic Simulation of Ice Accretion on Airfoils

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Addy, Harold E., Jr.; Bragg, Michael B.; Busch, Greg T.; Montreuil, Emmanuel

2011-01-01

This report describes recent improvements in aerodynamic scaling and simulation of ice accretion on airfoils. Ice accretions were classified into four types on the basis of aerodynamic effects: roughness, horn, streamwise, and spanwise ridge. The NASA Icing Research Tunnel (IRT) was used to generate ice accretions within these four types using both subscale and full-scale models. Large-scale, pressurized windtunnel testing was performed using a 72-in.- (1.83-m-) chord, NACA 23012 airfoil model with high-fidelity, three-dimensional castings of the IRT ice accretions. Performance data were recorded over Reynolds numbers from 4.5 x 10(exp 6) to 15.9 x 10(exp 6) and Mach numbers from 0.10 to 0.28. Lower fidelity ice-accretion simulation methods were developed and tested on an 18-in.- (0.46-m-) chord NACA 23012 airfoil model in a small-scale wind tunnel at a lower Reynolds number. The aerodynamic accuracy of the lower fidelity, subscale ice simulations was validated against the full-scale results for a factor of 4 reduction in model scale and a factor of 8 reduction in Reynolds number. This research has defined the level of geometric fidelity required for artificial ice shapes to yield aerodynamic performance results to within a known level of uncertainty and has culminated in a proposed methodology for subscale iced-airfoil aerodynamic simulation.
Experimental study of the impact of large-scale wind farms on land-atmosphere exchanges

NASA Astrophysics Data System (ADS)

Zhang, wei; Markfort, Corey; Porté-Agel, Fernando

2013-04-01

Wind energy is one of the fastest growing sources of renewable energy world-wide, and it is expected that many more large-scale wind farms will be built and cover a significant portion of land and ocean surfaces. By extracting kinetic energy from the atmospheric boundary layer and converting it to electricity, wind farms may affect the transport of momentum, heat, moisture and trace gases (e.g. CO2) between the atmosphere and the land surface locally and globally. Understanding wind farm-atmosphere interactions and subsequent environmental impacts are complicated by the effects of turbine array configuration, wind farm size, land-surface characteristics and atmospheric thermal stability. In particular, surface scalar flux is influenced by wind farms and needs to be appropriately parameterized in meso-scale and/or high-resolution numerical models. Wind-tunnel experiments of model wind farms with perfectly aligned and staggered configurations, having the same turbine distribution density, were conducted in a neutral turbulent boundary layer with a surface heat source. Turbulent flow and fluxes over and through the wind farm were measured using a custom x-wire/cold-wire anemometer; and surface scalar flux was measured with an array of surface-mounted heat flux sensors within the quasi-developed flow regime. Although the overall surface heat flux change produced by the wind farms was found to be small, with a net reduction of 4% for the staggered wind farm and nearly zero for the aligned wind farm, the highly heterogeneous spatial distribution of the surface heat flux, dependent on wind farm layout, is significant. The difference between the minimum and maximum surface heat fluxes could be up to 12% and 7% in aligned and staggered wind farms, respectively. This finding is important for planning intensive agriculture practices and optimizing agricultural land use with regard to wind energy project development. The well-controlled wind-tunnel experiments presented here
Wind-tunnel Tests of a Cyclogiro Rotor

NASA Technical Reports Server (NTRS)

Wheatley, John B; Windler, Ray

1935-01-01

During an extensive study of all types of rotating wings, the NACA examined the cyclogiro rotor and made an aerodynamic analysis of that system (reference 1). The examination disclosed that such a machine had sufficient promise to justify an experimental investigation; a model with a diameter and span of 8 feet was therefore constructed and tested in the 20-foot wind tunnel during 1934. The experimental work included tests of the effect of the motion upon the rotor forces during the static-lift and forward-flight conditions at several rotor speeds and the determination of the relations between the forces generated by the rotor and the power required by it.
Investigation of a Low-Drag Gun Port in the NACA Two-Dimensional Low-Turbulence Tunnel

NASA Technical Reports Server (NTRS)

Horton, Elmer A.; Woolard, Henry W.

1942-01-01

Tests were made in the NACA two-dimensional low-turbulence tunnel of three gun ports with a height of approximately 4 percent of the chord faired into an NACA 66,2-213 low-drag-airfoil section by bulging the section at the gun port. Gun ports faired in this manner had practically no effect on the maximum lift and the critical compressibility speed of the section and showed only small increase in the drag in the range of lift coefficients for high-speed and cruising-flight conditions.
Two methods for estimating limits to large-scale wind power generation

PubMed Central

Miller, Lee M.; Brunsell, Nathaniel A.; Mechem, David B.; Gans, Fabian; Monaghan, Andrew J.; Vautard, Robert; Keith, David W.; Kleidon, Axel

2015-01-01

Wind turbines remove kinetic energy from the atmospheric flow, which reduces wind speeds and limits generation rates of large wind farms. These interactions can be approximated using a vertical kinetic energy (VKE) flux method, which predicts that the maximum power generation potential is 26% of the instantaneous downward transport of kinetic energy using the preturbine climatology. We compare the energy flux method to the Weather Research and Forecasting (WRF) regional atmospheric model equipped with a wind turbine parameterization over a 105 km2 region in the central United States. The WRF simulations yield a maximum generation of 1.1 We⋅m−2, whereas the VKE method predicts the time series while underestimating the maximum generation rate by about 50%. Because VKE derives the generation limit from the preturbine climatology, potential changes in the vertical kinetic energy flux from the free atmosphere are not considered. Such changes are important at night when WRF estimates are about twice the VKE value because wind turbines interact with the decoupled nocturnal low-level jet in this region. Daytime estimates agree better to 20% because the wind turbines induce comparatively small changes to the downward kinetic energy flux. This combination of downward transport limits and wind speed reductions explains why large-scale wind power generation in windy regions is limited to about 1 We⋅m−2, with VKE capturing this combination in a comparatively simple way. PMID:26305925
Test-bed and Full-Scale Demonstration of Plasma Flow Control for Wind Turbines. Phase 1

DTIC Science & Technology

2013-07-15

the actuators was prohibitive. This led to the decision to mount the step-up transformers on the hub of the turbine , reducing the slip ring voltage...facility as it is manufactured as one piece and must be installed during assembly of the turbine . Figure 73 shows the slip ring after installation on...the turbine . The anti- rotation pin can be seen extending up past the brake disc at the top of the ring . Navatek, Ltd. Plasma Flow Control for Wind
Origin of the Two Scales of Wind Ripples on Mars

NASA Technical Reports Server (NTRS)

Lapotre, Mathieu G. A.; Ewing, Ryan C.; Lamb, Michael P.; Fischer, Woodward W.; Grotzinger, John P.; Rubin, David M.; Lewis, Kevin W.; Day, Mackenzie; Gupta, Sanjeev; Banham, Steeve G.;

2016-01-01

Earth's sandy deserts host two main types of bedforms - decimeter-scale ripples and larger dunes. Years of orbital observations on Mars also confirmed the existence of two modes of active eolian bedforms - meter-scale ripples, and dunes. By analogy to terrestrial ripples, which are thought to form from a grain mechanism, it was hypothesized that large martian ripples also formed from grain impacts, but spaced further apart due to elongated saltation trajectories from the lower martian gravity and different atmospheric properties. However, the Curiosity rover recently documented the coexistence of three scales of bedforms in Gale crater. Because a grain impact mechanism cannot readily explain two distinct and coeval ripple modes in similar sand sizes, a new mechanism seems to be required to explain one of the scales of ripples. Small ripples are most similar to Earth's impact ripples, with straight crests and subdued profiles. In contrast, large martian ripples are sinuous and asymmetric, with lee slopes dominated by grain flows and grainfall deposits. Thus, large martian ripples resemble current ripples formed underwater on Earth, suggesting that they may form from a fluid-drag mechanism. To test this hypothesis, we develop a scaling relation to predict the spacing of fluid-drag ripples from an extensive flume data compilation. The size of large martian ripples is predicted by our scaling relation when adjusted for martian atmospheric properties. Specifically, we propose that the wavelength of martian wind-drag ripples arises from the high kinematic viscosity of the low-density atmosphere. Because fluid density controls drag-ripple size, our scaling relation can help constrain paleoatmospheric density from wind-drag ripple stratification.

Origin of the two scales of wind ripples on Mars

NASA Astrophysics Data System (ADS)

Lapotre, M. G. A.; Ewing, R. C.; Lamb, M. P.; Fischer, W. W.; Grotzinger, J. P.; Rubin, D. M.; Lewis, K. W.; Ballard, M.; Day, M. D.; Gupta, S.; Banham, S.; Bridges, N.; Des Marais, D. J.; Fraeman, A. A.; Grant, J. A., III; Ming, D. W.; Mischna, M.; Rice, M. S.; Sumner, D. Y.; Vasavada, A. R.; Yingst, R. A.

2016-12-01

Earth's sandy deserts host two main types of bedforms - decimeter-scale ripples and larger dunes. Years of orbital observations on Mars also confirmed the existence of two modes of active eolian bedforms - meter-scale ripples, and dunes. By analogy to terrestrial ripples, which are thought to form from a grain mechanism, it was hypothesized that large martian ripples also formed from grain impacts, but spaced further apart due to elongated saltation trajectories from the lower martian gravity and different atmospheric properties. However, the Curiosity rover recently documented the coexistence of three scales of bedforms in Gale crater. Because a grain impact mechanism cannot readily explain two distinct and coeval ripple modes in similar sand sizes, a new mechanism seems to be required to explain one of the scales of ripples. Small ripples are most similar to Earth's impact ripples, with straight crests and subdued profiles. In contrast, large martian ripples are sinuous and asymmetric, with lee slopes dominated by grain flows and grainfall deposits. Thus, large martian ripples resemble current ripples formed underwater on Earth, suggesting that they may form from a fluid-drag mechanism. To test this hypothesis, we develop a scaling relation to predict the spacing of fluid-drag ripples from an extensive flume data compilation. The size of large martian ripples is predicted by our scaling relation when adjusted for martian atmospheric properties. Specifically, we propose that the wavelength of martian wind-drag ripples arises from the high kinematic viscosity of the low-density atmosphere. Because fluid density controls drag-ripple size, our scaling relation can help constrain paleoatmospheric density from wind-drag ripple stratification.
Scale Adaptive Simulation Model for the Darrieus Wind Turbine

NASA Astrophysics Data System (ADS)

Rogowski, K.; Hansen, M. O. L.; Maroński, R.; Lichota, P.

2016-09-01

Accurate prediction of aerodynamic loads for the Darrieus wind turbine using more or less complex aerodynamic models is still a challenge. One of the problems is the small amount of experimental data available to validate the numerical codes. The major objective of the present study is to examine the scale adaptive simulation (SAS) approach for performance analysis of a one-bladed Darrieus wind turbine working at a tip speed ratio of 5 and at a blade Reynolds number of 40 000. The three-dimensional incompressible unsteady Navier-Stokes equations are used. Numerical results of aerodynamic loads and wake velocity profiles behind the rotor are compared with experimental data taken from literature. The level of agreement between CFD and experimental results is reasonable.
Adaptive Control of a Utility-Scale Wind Turbine Operating in Region 3

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Balas, Mark J.; Wright, Alan D.

2009-01-01

Adaptive control techniques are well suited to nonlinear applications, such as wind turbines, which are difficult to accurately model and which have effects from poorly known operating environments. The turbulent and unpredictable conditions in which wind turbines operate create many challenges for their operation. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility scale, variable-speed horizontal axis wind turbine. The objective of the adaptive pitch controller in Region 3 is to regulate generator speed and reject step disturbances. The control objective is accomplished by collectively pitching the turbine blades. We use an extension of the Direct Model Reference Adaptive Control (DMRAC) approach to track a reference point and to reject persistent disturbances. The turbine simulation models the Controls Advanced Research Turbine (CART) of the National Renewable Energy Laboratory in Golden, Colorado. The CART is a utility-scale wind turbine which has a well-developed and extensively verified simulator. The adaptive collective pitch controller for Region 3 was compared in simulations with a bas celliansesical Proportional Integrator (PI) collective pitch controller. In the simulations, the adaptive pitch controller showed improved speed regulation in Region 3 when compared with the baseline PI pitch controller and it demonstrated robustness to modeling errors.
Wind Tunnel Tests of Ailerons at Various Speeds I : Ailerons of 0.20 Airfoil Chord and True Contour with 0.35 Aileron-chord Extreme Blunt Nose Balance on the NACA 66,2-216 Airfoil

NASA Technical Reports Server (NTRS)

Letko, W; Denaci, H. G.; Freed, C

1943-01-01

Hinge-moment, lift, and pressure-distribution measurements were made in the two-dimensional test section of the NACA stability tunnel on a blunt-nose balance-type aileron on an NACA 66,2-216 airfoil at speeds up to 360 miles per hour corresponding to a Mach number of 0.475. The tests were made primarily to determine the effect of speed on the action of this type of aileron. The balance-nose radii of the aileron were varied from 0 to 0.02 of the airfoil chord and the gap width was varied from 0.0005 to 0.0107 of the airfoil chord. Tests were also made with the gap sealed.
National Offshore Wind Energy Grid Interconnection Study Full Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, John P.; Liu, Shu; Ibanez, Eduardo

2014-07-30

The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States.
Simulation-Based Airframe Noise Prediction of a Full-Scale, Full Aircraft

NASA Technical Reports Server (NTRS)

Khorrami, Mehdi R.; Fares, Ehab

2016-01-01

A previously validated computational approach applied to an 18%-scale, semi-span Gulfstream aircraft model was extended to the full-scale, full-span aircraft in the present investigation. The full-scale flap and main landing gear geometries used in the simulations are nearly identical to those flown on the actual aircraft. The lattice Boltzmann solver PowerFLOW® was used to perform time-accurate predictions of the flow field associated with this aircraft. The simulations were performed at a Mach number of 0.2 with the flap deflected 39 deg. and main landing gear deployed (landing configuration). Special attention was paid to the accurate prediction of major sources of flap tip and main landing gear noise. Computed farfield noise spectra for three selected baseline configurations (flap deflected 39 deg. with and without main gear extended, and flap deflected 0 deg. with gear deployed) are presented. The flap brackets are shown to be important contributors to the farfield noise spectra in the mid- to high-frequency range. Simulated farfield noise spectra for the baseline configurations, obtained using a Ffowcs Williams and Hawkings acoustic analogy approach, were found to be in close agreement with acoustic measurements acquired during the 2006 NASA-Gulfstream joint flight test of the same aircraft.

SMART Rotor Development and Wind-Tunnel Test

NASA Technical Reports Server (NTRS)

Lau, Benton H.; Straub, Friedrich; Anand, V. R.; Birchette, Terry

2009-01-01

Boeing and a team from Air Force, NASA, Army, Massachusetts Institute of Technology, University of California at Los Angeles, and University of Maryland have successfully completed a wind-tunnel test of the smart material actuated rotor technology (SMART) rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center, figure 1. The SMART rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing-edge flap on each blade. The development effort included design, fabrication, and component testing of the rotor blades, the trailing-edge flaps, the piezoelectric actuators, the switching power amplifiers, the actuator control system, and the data/power system. Development of the smart rotor culminated in a whirl-tower hover test which demonstrated the functionality, robustness, and required authority of the active flap system. The eleven-week wind tunnel test program evaluated the forward flight characteristics of the active-flap rotor, gathered data to validate state-of-the-art codes for rotor noise analysis, and quantified the effects of open- and closed-loop active-flap control on rotor loads, noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness and the reliability of the flap actuation system were successfully demonstrated in more than 60 hours of wind-tunnel testing. The data acquired and lessons learned will be instrumental in maturing this technology and transitioning it into production. The development effort, test hardware, wind-tunnel test program, and test results will be presented in the full paper.
Effect of nacelle on wake meandering in a laboratory scale wind turbine using LES

NASA Astrophysics Data System (ADS)

Foti, Daniel; Yang, Xiaolei; Guala, Michele; Sotiropoulos, Fotis

2015-11-01

Wake meandering, large scale motion in the wind turbine wakes, has considerable effects on the velocity deficit and turbulence intensity in the turbine wake from the laboratory scale to utility scale wind turbines. In the dynamic wake meandering model, the wake meandering is assumed to be caused by large-scale atmospheric turbulence. On the other hand, Kang et al. (J. Fluid Mech., 2014) demonstrated that the nacelle geometry has a significant effect on the wake meandering of a hydrokinetic turbine, through the interaction of the inner wake of the nacelle vortex with the outer wake of the tip vortices. In this work, the significance of the nacelle on the wake meandering of a miniature wind turbine previously used in experiments (Howard et al., Phys. Fluid, 2015) is demonstrated with large eddy simulations (LES) using immersed boundary method with fine enough grids to resolve the turbine geometric characteristics. The three dimensionality of the wake meandering is analyzed in detail through turbulent spectra and meander reconstruction. The computed flow fields exhibit wake dynamics similar to those observed in the wind tunnel experiments and are analyzed to shed new light into the role of the energetic nacelle vortex on wake meandering. This work was supported by Department of Energy DOE (DE-EE0002980, DE-EE0005482 and DE-AC04-94AL85000), and Sandia National Laboratories. Computational resources were provided by Sandia National Laboratories and the University of Minnesota Supercomputing.
Probability density function characterization for aggregated large-scale wind power based on Weibull mixtures

DOE PAGES

Gomez-Lazaro, Emilio; Bueso, Maria C.; Kessler, Mathieu; ...

2016-02-02

Here, the Weibull probability distribution has been widely applied to characterize wind speeds for wind energy resources. Wind power generation modeling is different, however, due in particular to power curve limitations, wind turbine control methods, and transmission system operation requirements. These differences are even greater for aggregated wind power generation in power systems with high wind penetration. Consequently, models based on one-Weibull component can provide poor characterizations for aggregated wind power generation. With this aim, the present paper focuses on discussing Weibull mixtures to characterize the probability density function (PDF) for aggregated wind power generation. PDFs of wind power datamore » are firstly classified attending to hourly and seasonal patterns. The selection of the number of components in the mixture is analyzed through two well-known different criteria: the Akaike information criterion (AIC) and the Bayesian information criterion (BIC). Finally, the optimal number of Weibull components for maximum likelihood is explored for the defined patterns, including the estimated weight, scale, and shape parameters. Results show that multi-Weibull models are more suitable to characterize aggregated wind power data due to the impact of distributed generation, variety of wind speed values and wind power curtailment.« less
Variability of interconnected wind plants: correlation length and its dependence on variability time scale

DOE PAGES

St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

2015-04-02

The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. However, how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer 'how far is far enough,' we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25–2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high
Variability of interconnected wind plants: correlation length and its dependence on variability time scale

NASA Astrophysics Data System (ADS)

St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

2015-04-01

The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high
Constraining the Turbulence Scale and Mixing of a Crushed Pulsar Wind Nebula

NASA Astrophysics Data System (ADS)

Ng, Chi Yung; Ma, Y. K.; Bucciantini, Niccolo; Slane, Patrick O.; Gaensler, Bryan M.; Temim, Tea

2016-04-01

Pulsar wind nebulae (PWNe) are synchrotron-emitting nebulae resulting from the interaction between pulsars' relativistic particle outflows and the ambient medium. The Snail PWN in supernova remnant G327.1-1.1 is a rare system that has recently been crushed by supernova reverse shock. We carried out radio polarization observations with the Australia Telescope Compact Array and found highly ordered magnetic field structure in the nebula. This result is surprising, given the turbulent environment expected from hydrodynamical simulations. We developed a toymodel and compared simple simulations with observations to constrain the characteristic turbulence scale in the PWN and the mixing with supernova ejecta. We estimate that the turbulence scale is about one-eighth to one-sixth of the nebula radius and a pulsar wind filling factor of 50-75%. The latter implies substantial mixing of the pulsar wind with the surrounding supernova ejecta.This work is supported by an ECS grant of the Hong Kong Government under HKU 709713P. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
Scale Dependence of Magnetic Helicity in the Solar Wind

NASA Technical Reports Server (NTRS)

Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

2011-01-01

We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.
Downwind pre-aligned rotors for extreme-scale wind turbines

DOE PAGES

Loth, Eric; Steele, Adam; Qin, Chao; ...

2017-03-08

Downwind force angles are small for current turbines systems (1-5 MW) such that they may be readily accommodated by conventional upwind configurations. However, analysis indicates that extreme-scale systems (10-20 MW) will have larger angles that may benefit from downwind-aligned configurations. To examine potential rotor mass reduction, the pre-alignment concept was investigated a two-bladed configuration by keeping the structural and aerodynamic characteristics of each blade fixed (to avoids a complete blade re-design). Simulations for a 13.2 MW rated rotor at steady-state conditions show that this concept-level two-bladed design may yield 25% rotor mass savings while also reducing average blade stress overmore » all wind speeds. These results employed a pre-alignment on the basis of a wind speed of 1.25 times the rated wind speed. The downwind pre-aligned concept may also reduce damage equivalent loads on the blades by 60% for steady rated wind conditions. Even higher mass and damage equivalent load savings (relative to conventional upwind designs) may be possible for larger systems (15-20 MW) for which load-alignment angles become even larger. Furthermore, much more work is needed to determine whether this concept can be translated into a practical design that must meet a wide myriad of other criteria.« less
Downwind pre-aligned rotors for extreme-scale wind turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loth, Eric; Steele, Adam; Qin, Chao

Downwind force angles are small for current turbines systems (1-5 MW) such that they may be readily accommodated by conventional upwind configurations. However, analysis indicates that extreme-scale systems (10-20 MW) will have larger angles that may benefit from downwind-aligned configurations. To examine potential rotor mass reduction, the pre-alignment concept was investigated a two-bladed configuration by keeping the structural and aerodynamic characteristics of each blade fixed (to avoids a complete blade re-design). Simulations for a 13.2 MW rated rotor at steady-state conditions show that this concept-level two-bladed design may yield 25% rotor mass savings while also reducing average blade stress overmore » all wind speeds. These results employed a pre-alignment on the basis of a wind speed of 1.25 times the rated wind speed. The downwind pre-aligned concept may also reduce damage equivalent loads on the blades by 60% for steady rated wind conditions. Even higher mass and damage equivalent load savings (relative to conventional upwind designs) may be possible for larger systems (15-20 MW) for which load-alignment angles become even larger. Furthermore, much more work is needed to determine whether this concept can be translated into a practical design that must meet a wide myriad of other criteria.« less
An experimental investigation on wind turbine aeromechanics and wake interferences among multiple wind turbines

NASA Astrophysics Data System (ADS)

Ozbay, Ahmet

A comprehensive experimental study was conducted to investigate wind turbine aeromechanics and wake interferences among multiple wind turbines sited in onshore and offshore wind farms. The experiments were carried out in a large-scale Aerodynamic/Atmospheric Boundary Layer (AABL) Wind Tunnel available at Iowa State University. An array of scaled three-blade Horizontal Axial Wind Turbine (HAWT) models were placed in atmospheric boundary layer winds with different mean and turbulence characteristics to simulate the situations in onshore and offshore wind farms. The effects of the important design parameters for wind farm layout optimization, which include the mean and turbulence characteristics of the oncoming surface winds, the yaw angles of the turbines with respect to the oncoming surface winds, the array spacing and layout pattern, and the terrain topology of wind farms on the turbine performances (i.e., both power output and dynamic wind loadings) and the wake interferences among multiple wind turbines, were assessed in detail. The aeromechanic performance and near wake characteristics of a novel dual-rotor wind turbine (DRWT) design with co-rotating or counter-rotating configuration were also investigated, in comparison to a conventional single rotor wind turbine (SRWT). During the experiments, in addition to measuring dynamic wind loads (both forces and moments) and the power outputs of the scaled turbine models, a high-resolution Particle Image Velocity (PIV) system was used to conduct detailed flow field measurements (i.e., both free-run and phase-locked flow fields measurements) to reveal the transient behavior of the unsteady wake vortices and turbulent flow structures behind wind turbines and to quantify the characteristics of the wake interferences among the wind turbines sited in non-homogenous surface winds. A miniature cobra anemometer was also used to provide high-temporal-resolution data at points of interest to supplement the full field PIV
Security, protection, and control of power systems with large-scale wind power penetration

NASA Astrophysics Data System (ADS)

Acharya, Naresh

As the number of wind generation facilities in the utility system is fast increasing, many issues associated with their integration into the power system are beginning to emerge. Of the various issues, this dissertation deals with the development of new concepts and computational methods to handle the transmission issues and voltage issues caused by large-scale integration of wind turbines. This dissertation also formulates a probabilistic framework for the steady-state security assessment of wind power incorporating the forecast uncertainty and correlation. Transmission issues are mainly related to the overloading of transmission lines, when all the wind power generated cannot be delivered in full due to prior outage conditions. To deal with this problem, a method to curtail the wind turbine outputs through Energy Management System facilities in the on-line operational environment is proposed. The proposed method, which is based on linear optimization, sends the calculated control signals via the Supervisory Control and Data Acquisition system to wind farm controllers. The necessary ramping of the wind farm outputs is implemented either by the appropriate blade pitch angle control at the turbine level or by switching a certain number of turbines. The curtailment strategy is tested with an equivalent system model of MidAmerican Energy Company. The results show that the line overload in high wind areas can be alleviated by controlling the outputs of the wind farms step-by-step over an allowable period of time. A low voltage event during a system fault can cause a large number of wind turbines to trip, depending on voltages at the wind turbine terminals during the fault and the under-voltage protection setting of wind turbines. As a result, an N-1 contingency may evolve into an N-(K+1) contingency, where K is the number of wind farms tripped due to low voltage conditions. Losing a large amount of wind power following a line contingency might lead to system
Negative long term effects on harbour porpoises from a large scale offshore wind farm in the Baltic—evidence of slow recovery

NASA Astrophysics Data System (ADS)

Teilmann, Jonas; Carstensen, Jacob

2012-12-01

Offshore wind farms constitute a new and fast growing industry all over the world. This study investigates the long term impact on harbour porpoises, Phocoena phocoena, for more than 10 years (2001-12) from the first large scale offshore wind farm in the world, Nysted Offshore Wind Farm, in the Danish western Baltic Sea (72 × 2.3 MW turbines). The wind farm was brought into full operation in December 2003. At six stations, acoustic porpoise detectors (T-PODs) were placed inside the wind farm area and at a reference area 10 km to the east, to monitor porpoise echolocation activity as a proxy of porpoise presence. A modified statistical BACI design was applied to detect changes in porpoise presence before, during and after construction of the wind farm. The results show that the echolocation activity has significantly declined inside Nysted Offshore Wind Farm since the baseline in 2001-2 and has not fully recovered yet. The echolocation activity inside the wind farm has been gradually increasing (from 11% to 29% of the baseline level) since the construction of the wind farm, possibly due to habituation of the porpoises to the wind farm or enrichment of the environment due to reduced fishing and to artificial reef effects.
A Free-flight Wind Tunnel for Aerodynamic Testing at Hypersonic Speeds

NASA Technical Reports Server (NTRS)

Seiff, Alvin

1954-01-01

The supersonic free-flight wind tunnel is a facility at the Ames Laboratory of the NACA in which aerodynamic test models are gun-launched at high speed and directed upstream through the test section of a supersonic wind tunnel. In this way, test Mach numbers up to 10 have been attained and indications are that still higher speeds will be realized. An advantage of this technique is that the air and model temperatures simulate those of flight through the atmosphere. Also the Reynolds numbers are high. Aerodynamic measurements are made from photographic observation of the model flight. Instruments and techniques have been developed for measuring the following aerodynamic properties: drag, initial lift-curve slope, initial pitching-moment-curve slope, center of pressure, skin friction, boundary-layer transition, damping in roll, and aileron effectiveness. (author)
Evaluation of the Water Film Weber Number in Glaze Icing Scaling

NASA Technical Reports Server (NTRS)

Tsao, Jen-Ching; Kreeger, Richard E.; Feo, Alejandro

2010-01-01

Icing scaling tests were performed in the NASA Glenn Icing Research Tunnel to evaluate a new scaling method, developed and proposed by Feo for glaze icing, in which the scale liquid water content and velocity were found by matching reference and scale values of the nondimensional water-film thickness expression and the film Weber number. For comparison purpose, tests were also conducted using the constant We(sub L) method for velocity scaling. The reference tests used a full-span, fiberglass, 91.4-cm-chord NACA 0012 model with velocities of 76 and 100 knot and MVD sizes of 150 and 195 microns. Scale-to-reference model size ratio was 1:2.6. All tests were made at 0deg AOA. Results will be presented for stagnation point freezing fractions of 0.3 and 0.5.
Large-scale structures of solar wind and dynamics of parameters in them

NASA Astrophysics Data System (ADS)

Yermolaev, Yuri; Lodkina, Irina; Yermolaev, Michael

2017-04-01

On the basis of OMNI dataset and our catalog of large-scale solar wind (SW) phenomena (see web-site ftp://ftp.iki.rssi.ru/pub/omni/ and paper by Yermolaev et al., 2009) we study temporal profile of interplanetary and magnetospheric parameters in following SW phenomena: interplanetary manifestation of coronal mass ejection (ICME) including magnetic cloud (MC) and Ejecta, Sheath—compression region before ICME and corotating interaction region (CIR)—compression region before high-speed stream (HSS) of solar wind. To take into account a possible influence of other SW types, following sequences of phenomena, which include all typical sequences of non-stationary SW events, are analyzed: (1) SW/ CIR/ SW, (2) SW/ IS/ CIR/ SW, (3) SW/ Ejecta/ SW, (4) SW/ Sheath/Ejecta/ SW, (5) SW/ IS/ Sheath/ Ejecta/ SW, (6) SW/ MC/ SW, (7) SW/Sheath/ MC/ SW, (8) SW/ IS/ Sheath/ MC/ SW (where SW is undisturbed solar wind, and IS is interplanetary shock) (Yermolaev et al., 2015) using the method of double superposed epoch analysis for large numbers of events (Yermolaev et al., 2010). Similarities and distinctions of different SW phenomena depending on neighboring SW types and their geoeffectiveness are discussed. The work was supported by the Russian Science Foundation, projects 16-12-10062. References: Yermolaev, Yu. I., N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev (2009), Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research, , Vol. 47, No. 2, pp. 81-94. Yermolaev, Y. I., N. S. Nikolaeva, I. G. Lodkina, and M. Y. Yermolaev (2010), Specific interplanetary conditions for CIR-induced, Sheath-induced, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis, Ann. Geophys., 28, pp. 2177-2186. Yermolaev, Yu. I., I. G. Lodkina, N. S. Nikolaeva, and M. Yu. Yermolaev (2015), Dynamics of large-scale solar wind streams obtained by the double superposed epoch analysis, J. Geophys. Res. Space Physics, 120, doi:10.1002/2015JA021274.
Computational Aerodynamic Analysis of Three-Dimensional Ice Shapes on a NACA 23012 Airfoil

NASA Technical Reports Server (NTRS)

Jun, GaRam; Oliden, Daniel; Potapczuk, Mark G.; Tsao, Jen-Ching

2014-01-01

The present study identifies a process for performing computational fluid dynamic calculations of the flow over full three-dimensional (3D) representations of complex ice shapes deposited on aircraft surfaces. Rime and glaze icing geometries formed on a NACA23012 airfoil were obtained during testing in the NASA Glenn Research Centers Icing Research Tunnel (IRT). The ice shape geometries were scanned as a cloud of data points using a 3D laser scanner. The data point clouds were meshed using Geomagic software to create highly accurate models of the ice surface. The surface data was imported into Pointwise grid generation software to create the CFD surface and volume grids. It was determined that generating grids in Pointwise for complex 3D icing geometries was possible using various techniques that depended on the ice shape. Computations of the flow fields over these ice shapes were performed using the NASA National Combustion Code (NCC). Results for a rime ice shape for angle of attack conditions ranging from 0 to 10 degrees and for freestream Mach numbers of 0.10 and 0.18 are presented. For validation of the computational results, comparisons were made to test results from rapid-prototype models of the selected ice accretion shapes, obtained from a separate study in a subsonic wind tunnel at the University of Illinois at Urbana-Champaign. The computational and experimental results were compared for values of pressure coefficient and lift. Initial results show fairly good agreement for rime ice accretion simulations across the range of conditions examined. The glaze ice results are promising but require some further examination.
Computational Aerodynamic Analysis of Three-Dimensional Ice Shapes on a NACA 23012 Airfoil

NASA Technical Reports Server (NTRS)

Jun, Garam; Oliden, Daniel; Potapczuk, Mark G.; Tsao, Jen-Ching

2014-01-01

The present study identifies a process for performing computational fluid dynamic calculations of the flow over full three-dimensional (3D) representations of complex ice shapes deposited on aircraft surfaces. Rime and glaze icing geometries formed on a NACA23012 airfoil were obtained during testing in the NASA Glenn Research Center's Icing Research Tunnel (IRT). The ice shape geometries were scanned as a cloud of data points using a 3D laser scanner. The data point clouds were meshed using Geomagic software to create highly accurate models of the ice surface. The surface data was imported into Pointwise grid generation software to create the CFD surface and volume grids. It was determined that generating grids in Pointwise for complex 3D icing geometries was possible using various techniques that depended on the ice shape. Computations of the flow fields over these ice shapes were performed using the NASA National Combustion Code (NCC). Results for a rime ice shape for angle of attack conditions ranging from 0 to 10 degrees and for freestream Mach numbers of 0.10 and 0.18 are presented. For validation of the computational results, comparisons were made to test results from rapid-prototype models of the selected ice accretion shapes, obtained from a separate study in a subsonic wind tunnel at the University of Illinois at Urbana-Champaign. The computational and experimental results were compared for values of pressure coefficient and lift. Initial results show fairly good agreement for rime ice accretion simulations across the range of conditions examined. The glaze ice results are promising but require some further examination.
McDonnell FH-1 Phantom Destroyed for the NACA Crash Fire Program

NASA Image and Video Library

1955-04-21

Researchers at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory purposely wreck a McDonnell FH-1 Phantom as part of the laboratory’s Crash Fire Program. NACA Lewis researchers created the program in 1949 to investigate methods for improving survival rates for take-off and landing-type crashes. In these types of crashes, the passengers often survived the impact only to perish in the ensuing fire. Previously there had been little information on the nature of post-crash fires, and it was difficult to use analytical studies in this area. Irving Pinkel, Chief of the Lewis Flight Propulsion Division, was the primary researcher. He enlisted flight safety specialist and aeronautics researchers G. Merritt Preston and Gerard Pesman, mechanical engineer Dugald Black, and others. The tests were conducted at the nearby Ravenna Arsenal using decommissioned Air Force fighter and transport aircraft. The pilotless aircraft were accelerated down a rail on a 1700-foot track at take-off speeds and run into barriers to simulate a variety of different types of crashes. The first barrier stripped off the landing gears and another briefly sent the aircraft off the ground before it crashed into a dirt mound. Telemetry and high-speed cameras were crucial elements in these studies. NACA Lewis photographer Bill Wynne developed a method for inserting timekeeping devices on test film that were able to show time to one thousandth of a second.
Self streamlining wind tunnel: Further low speed testing and final design studies for the transonic facility

NASA Technical Reports Server (NTRS)

Wolf, S. W. D.

1977-01-01

Work has continued with the low speed self streamlining wind tunnel (SSWT) using the NACA 0012-64 airfoil in an effort to explain the discrepancies between the NASA Langley low turbulence pressure tunnel (LTPT) and SSWT results obtained with the airfoil stalled. Conventional wind tunnel corrections were applied to straight wall SSWT airfoil data, to illustrate the inadequacy of standard correction techniques in circumstances of high blockage. Also one SSWT test was re-run at different air speeds to investigate the effects of such changes on airfoil data and wall contours. Mechanical design analyses for the transonic self streamlining wind tunnel (TSWT) were completed by the application of theoretical airfoil flow field data to the elastic beam and streamline analysis. The control system for the transonic facility is outlined.
Self streamlining wind tunnel: Further low speed testing and final design studies for the transonic facility

NASA Technical Reports Server (NTRS)

Wolf, S. W. D.

1978-01-01

Work was continued with the low speed self streamlining wind tunnel (SSWT) using the NACA 0012-64 airfoil in an effort to explain the discrepancies between the NASA Langley low turbulence pressure tunnel (LTPT) and SSWT results obtained with the airfoil stalled. Conventional wind tunnel corrections were applied to straight wall SSWT airfoil data, to illustrate the inadequacy of standard correction techniques in circumstances of high blockage. Also one SSWT test was re-run at different air speeds to investigate the effects of such changes (perhaps through changes in Reynold's number and freestream turbulence levels) on airfoil data and wall contours. Mechanical design analyses for the transonic self-streamlining wind tunnel (TSWT) were completed by the application of theoretical airfoil flow field data to the elastic beam and streamline analysis. The control system for the transonic facility, which will eventually allow on-line computer operation of the wind tunnel, was outlined.

NACA Mechanics in an Allison Engine Training Class

NASA Image and Video Library

1943-10-21

The Allison Engine Company's A.G. Covell instructs mechanics from various divisions at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory on the operation of the Allison Basic Engine. The military had asked that the laboratory undertake an extensive program to improve the performance of the Allison V–1710 engine. The V–1710 was the only liquid-cooled engine used during World War II, and the military counted on it to power several types of fighter aircraft. The NACA instituted an Apprentice Program during the war to educate future mechanics, technicians, and electricians. The program was suspended for a number of years due to the increasing rates of military service by its participants. The laboratory continued its in-house education during the war, however, by offering a number of classes to its employees and lectures for the research staff. The classes and lectures were usually taught by fellow members of the staff, but occasionally external experts were brought in. The students in the Allison class in the Engine Research Building were taught how to completely disassemble and reassemble the engine components and systems. From left to right are Don Vining, Ed Cudlin, Gus DiNovo, George Larsen, Charles Diggs, Martin Lipes, Harley Roberts, Martin Berwaldt and John Dempsey. A.G. Covell is standing.
Extracting full-field dynamic strain response of a rotating wind turbine using photogrammetry

NASA Astrophysics Data System (ADS)

Baqersad, Javad; Poozesh, Peyman; Niezrecki, Christopher; Avitabile, Peter

2015-04-01

Health monitoring of wind turbines is typically performed using conventional sensors (e.g. strain-gages and accelerometers) that are usually mounted to the nacelle or gearbox. Although many wind turbines stop operating due to blade failures, there are typically few to no sensor mounted on the blades. Placing sensors on the rotating parts of the structure is a challenge due to the wiring and data transmission constraints. Within the current work, an approach to monitor full-field dynamic response of rotating structures (e.g. wind turbine blades or helicopter rotors) is developed and experimentally verified. A wind turbine rotor was used as the test structure and was mounted to a block and horizontally placed on the ground. A pair of bearings connected to the rotor shaft allowed the turbine to freely spin along the shaft. Several optical targets were mounted to the blades and a pair of high-speed cameras was used to monitor the dynamics of the spinning turbine. Displacements of the targets during rotation were measured using three-dimensional point tracking. The point tracking technique measured both rigid body displacement and flexible deformation of the blades at target locations. While the structure is rotating, only flap displacements of optical targets (displacements out of the rotation plane) were used in strain prediction process. The measured displacements were expanded and applied to the finite element model of the turbine to extract full-field dynamic strain on the structure. The proposed approach enabled the prediction of dynamic response on the outer surface as well as within the inner points of the structure where no other sensor could be easily mounted. In order to validate the proposed approach, the predicted strain was compared to strain measured at four locations on the spinning blades using a wireless strain-gage system.
Experimental characterization of vertical-axis wind turbine noise.

PubMed

Pearson, C E; Graham, W R

2015-01-01

Vertical-axis wind turbines are wind-energy generators suitable for use in urban environments. Their associated noise thus needs to be characterized and understood. As a first step, this work investigates the relative importance of harmonic and broadband contributions via model-scale wind-tunnel experiments. Cross-spectra from a pair of flush-mounted wall microphones exhibit both components, but further analysis shows that the broadband dominates at frequencies corresponding to the audible range in full-scale operation. This observation has detrimental implications for noise-prediction reliability and hence also for acoustic design optimization.
Influence of time scale wind speed data on sustainability analysis for irrigating greenhouse crops

NASA Astrophysics Data System (ADS)

Díaz Méndez, Rodrigo; García Llaneza, Joaquín; Peillón, Manuel; Perdigones, Alicia; Sanchez, Raul; Tarquis, Ana M.; Garcia, Jose Luis

2014-05-01

Appropriate water supply at crop/farm level, with suitable costs, is becoming more and more important. Energy management is closely related to water supply in this context, being wind energy one of the options to be considered, using wind pumps for irrigation water supply. Therefore, it is important to characterize the wind speed frequency distribution to study the technical feasibility to use its energy for irrigation management purpose. The general objective of this present research is to analyze the impact of time scale recorded wind speed data in the sustainability for tomato (Solanum lycopersicum L.) grown under greenhouse at Cuban conditions using drip irrigation system. For this porpoise, a daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. Several factors were included: wind velocity (W, m/s) in function of the time scale averaged, flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors. Three-hourly wind velocity (W3h, m/s) data from 1992 till 2008 was available for this study. The original data was grouped in six and twelve hourly data (W6h and W12h respectively) as well as daily data (W24h). For each time scale the daily estimation balance was applied. A comparison of the results points out a need for at least three-hourly data to be used mainly in the months in which mean wind speed are close or below the pumps threshold speed to start-up functioning. References Manuel Esteban Peillon Mesa, Ana Maria Tarquis Alfonso, José Luis García Fernández, and Raúl Sánchez Calvo. The use of wind pumps for irrigating greenhouse tomato crops: a case study in Cuba. Geophysical
On the functional design of the DTU10 MW wind turbine scale model of LIFES50+ project

NASA Astrophysics Data System (ADS)

Bayati, I.; Belloli, M.; Bernini, L.; Fiore, E.; Giberti, H.; Zasso, A.

2016-09-01

This paper illustrates the mechatronic design of the wind tunnel scale model of the DTU 10MW reference wind turbine, for the LIFES50+ H2020 European project. This model was designed with the final goal of controlling the angle of attack of each blade by means of miniaturized servomotors, for implementing advanced individual pitch control (IPC) laws on a Floating Offshore Wind Turbine (FOWT) 1/75 scale model. Many design constraints were to be respected: among others, the rotor-nacelle overall mass due to aero-elastic scaling, the limited space of the nacelle, where to put three miniaturized servomotors and the main shaft one, with their own inverters/controllers, the slip rings for electrical rotary contacts, the highest stiffness as possible for the nacelle support and the blade-rotor connections, for ensuring the proper kinematic constraint, considering the first flapwise blade natural frequency, the performance of the servomotors to guarantee the wide frequency band due to frequency scale factors, etc. The design and technical solutions are herein presented and discussed, along with an overview of the building and verification process. Also a discussion about the goals achieved and constraints respected for the rigid wind turbine scale model (LIFES50+ deliverable D.3.1) and the further possible improvements for the IPC-aero-elastic scale model, which is being finalized at the time of this paper.
Scaling Relations of Starburst-driven Galactic Winds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanner, Ryan; Cecil, Gerald; Heitsch, Fabian, E-mail: rytanner@augusta.edu

2017-07-10

Using synthetic absorption lines generated from 3D hydrodynamical simulations, we explore how the velocity of a starburst-driven galactic wind correlates with the star formation rate (SFR) and SFR density. We find strong correlations for neutral and low ionized gas, but no correlation for highly ionized gas. The correlations for neutral and low ionized gas only hold for SFRs below a critical limit set by the mass loading of the starburst, above which point the scaling relations flatten abruptly. Below this point the scaling relations depend on the temperature regime being probed by the absorption line, not on the mass loading.more » The exact scaling relation depends on whether the maximum or mean velocity of the absorption line is used. We find that the outflow velocity of neutral gas can be up to five times lower than the average velocity of ionized gas, with the velocity difference increasing for higher ionization states. Furthermore, the velocity difference depends on both the SFR and mass loading of the starburst. Thus, absorption lines of neutral or low ionized gas cannot easily be used as a proxy for the outflow velocity of the hot gas.« less
Blade Displacement Predictions for the Full-Scale UH-60A Airloads Rotor

NASA Technical Reports Server (NTRS)

Bledron, Robert T.; Lee-Rausch, Elizabeth M.

2014-01-01

An unsteady Reynolds-Averaged Navier-Stokes solver for unstructured grids is loosely coupled to a rotorcraft comprehensive code and used to simulate two different test conditions from a wind-tunnel test of a full-scale UH-60A rotor. Performance data and sectional airloads from the simulation are compared with corresponding tunnel data to assess the level of fidelity of the aerodynamic aspects of the simulation. The focus then turns to a comparison of the blade displacements, both rigid (blade root) and elastic. Comparisons of computed root motions are made with data from three independent measurement systems. Finally, comparisons are made between computed elastic bending and elastic twist, and the corresponding measurements obtained from a photogrammetry system. Overall the correlation between computed and measured displacements was good, especially for the root pitch and lag motions and the elastic bending deformation. The correlation of root lead-lag motion and elastic twist deformation was less favorable.
Comparison of sub-scaled to full-scaled aircrafts in simulation environment for air traffic management

NASA Astrophysics Data System (ADS)

Elbakary, Mohamed I.; Iftekharuddin, Khan M.; Papelis, Yiannis; Newman, Brett

2017-05-01

Air Traffic Management (ATM) concepts are commonly tested in simulation to obtain preliminary results and validate the concepts before adoption. Recently, the researchers found that simulation is not enough because of complexity associated with ATM concepts. In other words, full-scale tests must eventually take place to provide compelling performance evidence before adopting full implementation. Testing using full-scale aircraft produces a high-cost approach that yields high-confidence results but simulation provides a low-risk/low-cost approach with reduced confidence on the results. One possible approach to increase the confidence of the results and simultaneously reduce the risk and the cost is using unmanned sub-scale aircraft in testing new concepts for ATM. This paper presents the simulation results of using unmanned sub-scale aircraft in implementing ATM concepts compared to the full scale aircraft. The results of simulation show that the performance of sub-scale is quite comparable to that of the full-scale which validates use of the sub-scale in testing new ATM concepts. Keywords: Unmanned
Flexible Blades for Wind Turbines

NASA Astrophysics Data System (ADS)

Collins, Madeline Carlisle; Macphee, David; Harris, Caleb

2016-11-01

Previous research has shown that windmills with flexible blades are more efficient than those with rigid blades. Flexibility offers passive pitch control, preferable to active pitch control which is costly and requires maintenance. Flexible blades morph such that the blade more closely resembles its design point at part load and over load. The lift-to-drag ratios on individual blades was investigated. A mold was designed and machined from an acrylic slab for the casting of blades with a NACA 0012 cross section. A flexible blade was cast from silicone and a rigid blade was cast from polyurethane. Each of these blades was tested in a wind tunnel, cantilever mounted, spanning the whole test section. The angle of attack was varied by rotating the mount. All tests were performed at the same wind speed. A load cell within the mount measured forces on the blade, from which the lift and drag forces were calculated. The stall point for the flexible blade occurred later than for the rigid blade, which agrees with previous research. Lift-to-drag ratios were larger for the flexible blade at all angles of attack tested. Flexible blades seem to be a viable option for passive pitch control. Future research will include different airfoil cross sections, wind speeds, and blade materials. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.
Wind Tunnel Investigation of Ground Wind Loads for Ares Launch Vehicle

NASA Technical Reports Server (NTRS)

Keller, Donald F.; Ivanco, Thomas G.

2010-01-01

the Ares I-X GWL model test was used in the determination of worst-case loads for the analysis of Ares I-X FTV design wind conditions. Finally, this paper includes a brief discussion of the limited full-scale GWL data acquired during the rollout and on-pad stay of the Ares I-X FTV that was launched from KSC on October 28, 2009.
The Effect of an Operating Propeller on the Aerodynamic Characteristics of a 1/10-Scale Model of the Lockheed XFV-1 Airplane at High Subsonic Speeds (TED No. NACA DE-377)

NASA Technical Reports Server (NTRS)

Sutton, Fred B.; Buell, Donald A.

1952-01-01

An investigation was conducted in the Ames 12-foot pressure wind tunnel to determine the effect of an operating propeller on the aerodynamic characteristics of a l/l9-scale model of the Lockheed XFV-1 airplane, Several full-scale power conditions were simulated at Mach numbers from 0.50 to 0.92; the.Reynolds number was constant at 1,7 million. Lift, longitudinal force, pitch, roll, and yaw characteristics, determined with and without power, are presented for the complete model and for various combinations of model components, Results of an investigation to determine the characteristics of the dual-rotating propeller used on the model are given also,
Flow widening through a Darrieus wind turbine - Theory and experiment

NASA Astrophysics Data System (ADS)

Comolet, R.; Harajli, I.; Mercier Des Rochettes, P.; Yeznasni, A.

1982-11-01

A two-dimensional multiple stream tube model is developed for the air flow through a Darrieus wind turbine. The model is configured to account for the widening of the flux tubes as they cross the interior of the actuator disk. Note is made of the lateral broadening of the flow as it moves through the area, leaving a turbulent wake. A relation is defined between the variation in the kinetic energy of the flow and the aerodynamic forces acting on the blades. The global efficiency and the power output of the machine are calculated. Experimental results are reported for a machine equipped with two NACA 0015 blades, each 110 cm long and with a 10 cm chord. The Darrieus had a 1 m diam and was tested in a wind tunnel at wind speeds of 0-18 m/sec. Soap bubbles inflated with He were used for visualization. Power output was found to match prediction. The model is recommended for use in calculating the forces acting on the machine and studying vibration and fatigue causative mechanisms.
Reynolds number effects on the aerodynamic characteristics of irregular planform wings at Mach number 0.3. [in the Ames 12 ft pressure wind tunnel

NASA Technical Reports Server (NTRS)

Kruse, R. L.; Lovette, G. H.; Spencer, B., Jr.

1977-01-01

The subsonic aerodynamic characteristics of a series of irregular planform wings were studied in wind tunnel tests conducted at M = 0.3 over a range of Reynolds numbers from 1.6 million to 26 million/m. The five basic wing planforms varied from a trapezoidal to a delta shape. Leading edge extensions, added to the basic shape, varied in approximately 5 deg increments from the wing leading edge sweep-back angle to a maximum 80 deg. Most of the tests were conducted using an NACA 0008 airfoil section with grit boundary layer trips. Tests were also conducted using an NACA 0012 airfoil section and an 8% thick wedge. In addition, the effect of free transition (no grit) was investigated. A body was used on all models.
Integrated Resilient Aircraft Control Project Full Scale Flight Validation

NASA Technical Reports Server (NTRS)

Bosworth, John T.

2009-01-01

Objective: Provide validation of adaptive control law concepts through full scale flight evaluation. Technical Approach: a) Engage failure mode - destabilizing or frozen surface. b) Perform formation flight and air-to-air tracking tasks. Evaluate adaptive algorithm: a) Stability metrics. b) Model following metrics. Full scale flight testing provides an ability to validate different adaptive flight control approaches. Full scale flight testing adds credence to NASA's research efforts. A sustained research effort is required to remove the road blocks and provide adaptive control as a viable design solution for increased aircraft resilience.
A fiber-optic ice detection system for large-scale wind turbine blades

NASA Astrophysics Data System (ADS)

Kim, Dae-gil; Sampath, Umesh; Kim, Hyunjin; Song, Minho

2017-09-01

Icing causes substantial problems in the integrity of large-scale wind turbines. In this work, a fiber-optic sensor system for detection of icing with an arrayed waveguide grating is presented. The sensor system detects Fresnel reflections from the ends of the fibers. The transition in Fresnel reflection due to icing gives peculiar intensity variations, which categorizes the ice, the water, and the air medium on the wind turbine blades. From the experimental results, with the proposed sensor system, the formation of icing conditions and thickness of ice were identified successfully in real time.
The effect of vegetation patterns on wind-blown mass transport at the regional scale: A wind tunnel experiment

NASA Astrophysics Data System (ADS)

Youssef, Feras; Visser, Saskia M.; Karssenberg, Derek; Erpul, Gunay; Cornelis, Wim M.; Gabriels, Donald; Poortinga, Ate

2012-07-01

Wind erosion is a global environmental problem. Re-vegetating land is a commonly used method to reduce the negative effects of wind erosion. However, there is limited knowledge on the effect of vegetation pattern on wind-blown mass transport. The objective of this study was to investigate the effect of vegetation pattern on this phenomenon within a land unit and at the border between land units. Wind tunnel experiments were conducted with artificial shrubs representing Atriplex halimus. Wind runs at a speed of 11 m s- 1 were conducted and sand translocation was measured after 200-230 s using a graph paper prepared for this purpose. This research showed that: 1) the transport within a land unit is affected by the neighboring land units and by the vegetation pattern within both the unit itself and the neighboring land units; 2) re-vegetation plans for degraded land can take into account the 'streets' effect (zones of erosion areas similar to streets); 3) the effect of neighboring land units includes sheltering effect and the regulation of sediment passing from one land unit to the neighboring land units and 4) in addition to investigation of the general effect of vegetation pattern on erosion and deposition within the region, it is important to investigate the redistribution of sediment at smaller scales depending on the scope of the project.
Modulation of the reaction cycle of the Na+:Ca2+, K+ exchanger.

PubMed

Vedovato, Natascia; Rispoli, Giorgio

2007-09-01

Ca(2+) concentration in retinal photoreceptor rod outer segment (OS) strongly affects the generator potential kinetics and the receptor light adaptation. The response to intense light stimuli delivered in the dark produce potential changes exceeding 40 mV: since the Ca(2+) extrusion in the OS is entirely controlled by the Na(+):Ca(2+), K(+) exchanger, it is important to assess how the exchanger ion transport rate is affected by the voltage and, in general, by intracellular factors. It is indeed known that the cardiac Na(+):Ca(2+) exchanger is regulated by Mg-ATP via a still unknown metabolic pathway. In the present work, the Na(+):Ca(2+), K(+) exchanger regulation was investigated in isolated OS, recorded in whole-cell configuration, using ionic conditions that activated maximally the exchanger in both forward and reverse mode. In all species examined (amphibia: Rana esculenta and Ambystoma mexicanum; reptilia: Gecko gecko), the forward (reverse) exchange current increased about linearly for negative (positive) voltages and exhibited outward (inward) rectification for positive (negative) voltages. Since hyperpolarisation increases Ca(2+) extrusion rate, the recovery of the dark level of Ca(2+) (and, in turn, of the generator potential) after intense light stimuli results accelerated. Mg-ATP increased the size of forward and reverse exchange current by a factor of approximately 2.3 and approximately 2.6, respectively, without modifying their voltage dependence. This indicates that Mg-ATP regulates the number of active exchanger sites and/or the exchanger turnover number, although via an unknown mechanism.
An Analysis of Model Scale Data Transformation to Full Scale Flight Using Chevron Nozzles

NASA Technical Reports Server (NTRS)

Brown, Clifford; Bridges, James

2003-01-01

Ground-based model scale aeroacoustic data is frequently used to predict the results of flight tests while saving time and money. The value of a model scale test is therefore dependent on how well the data can be transformed to the full scale conditions. In the spring of 2000, a model scale test was conducted to prove the value of chevron nozzles as a noise reduction device for turbojet applications. The chevron nozzle reduced noise by 2 EPNdB at an engine pressure ratio of 2.3 compared to that of the standard conic nozzle. This result led to a full scale flyover test in the spring of 2001 to verify these results. The flyover test confirmed the 2 EPNdB reduction predicted by the model scale test one year earlier. However, further analysis of the data revealed that the spectra and directivity, both on an OASPL and PNL basis, do not agree in either shape or absolute level. This paper explores these differences in an effort to improve the data transformation from model scale to full scale.
Multifractal two-scale Cantor set model for slow solar wind turbulence in the outer heliosphere during solar maximum

NASA Astrophysics Data System (ADS)

Macek, W. M.; Wawrzaszek, A.

2011-05-01

To quantify solar wind turbulence, we consider a generalized two-scale weighted Cantor set with two different scales describing nonuniform distribution of the kinetic energy flux between cascading eddies of various sizes. We examine generalized dimensions and the corresponding multifractal singularity spectrum depending on one probability measure parameter and two rescaling parameters. In particular, we analyse time series of velocities of the slow speed streams of the solar wind measured in situ by Voyager 2 spacecraft in the outer heliosphere during solar maximum at various distances from the Sun: 10, 30, and 65 AU. This allows us to look at the evolution of multifractal intermittent scaling of the solar wind in the distant heliosphere. Namely, it appears that while the degree of multifractality for the solar wind during solar maximum is only weakly correlated with the heliospheric distance, but the multifractal spectrum could substantially be asymmetric in a very distant heliosphere beyond the planetary orbits. Therefore, one could expect that this scaling near the frontiers of the heliosphere should rather be asymmetric. It is worth noting that for the model with two different scaling parameters a better agreement with the solar wind data is obtained, especially for the negative index of the generalized dimensions. Therefore we argue that there is a need to use a two-scale cascade model. Hence we propose this model as a useful tool for analysis of intermittent turbulence in various environments and we hope that our general asymmetric multifractal model could shed more light on the nature of turbulence.
Kinetic scale turbulence and dissipation in the solar wind: key observational results and future outlook

PubMed Central

Goldstein, M. L.; Wicks, R. T.; Perri, S.; Sahraoui, F.

2015-01-01

Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of turbulence to solar wind dynamics. PMID:25848084

Modeling the Distribution of Migratory Bird Stopovers to Inform Landscape-Scale Siting of Wind Development

PubMed Central

Pocewicz, Amy; Estes-Zumpf, Wendy A.; Andersen, Mark D.; Copeland, Holly E.; Keinath, Douglas A.; Griscom, Hannah R.

2013-01-01

Conservation of migratory birds requires understanding the distribution of and potential threats to their migratory habitats. However, although migratory birds are protected under international treaties, few maps have been available to represent migration at a landscape scale useful to target conservation efforts or inform the siting of wind energy developments that may affect migratory birds. To fill this gap, we developed models that predict where four groups of birds concentrate or stopover during their migration through the state of Wyoming, USA: raptors, wetland, riparian and sparse grassland birds. The models were based on existing literature and expert knowledge concerning bird migration behavior and ecology and validated using expert ratings and known occurrences. There was significant agreement between migratory occurrence data and migration models for all groups except raptors, and all models ranked well with experts. We measured the overlap between the migration concentration models and a predictive model of wind energy development to assess the potential exposure of migratory birds to wind development and illustrate the utility of migratory concentration models for landscape-scale planning. Wind development potential is high across 15% of Wyoming, and 73% of this high potential area intersects important migration concentration areas. From 5.2% to 18.8% of each group’s important migration areas was represented within this high wind potential area, with the highest exposures for sparse grassland birds and the lowest for riparian birds. Our approach could be replicated elsewhere to fill critical data gaps and better inform conservation priorities and landscape-scale planning for migratory birds. PMID:24098379
Comparative assessment of turbulence model in predicting airflow over a NACA 0010 airfoil

NASA Astrophysics Data System (ADS)

Panday, Shoyon; Khan, Nafiz Ahmed; Rasel, Md; Faisal, Kh. Md.; Salam, Md. Abdus

2017-06-01

Nowadays the role of computational fluid dynamics to predict the flow behavior over airfoil is quite prominent. Most often a 2-D subsonic flow simulation is carried out over an airfoil at a certain Reynolds number and various angles of attack obtained by different turbulence models those are based on governing equations. The commonly used turbulence models are K-ɛpsilon, K-omega, Spalart Allmaras etc. Variation in turbulence model effectively influences the result of analysis. Here a comparative study is represented to show the effect of different turbulence models for a 2-D flow analysis over a National Advisory Committee for Aeronautics (NACA) airfoil 0010. This airfoil was analysed at 200000 Re number in 10 different angle of attacks at a constant speed of 21.6 m/s. Numbers of two dimensional flow simulation was run by changing the turbulence model, for each AOA. In accordance with the variation of result for different turbulence model, it was also found that for which model, attained result is close enough to experimental outcome from a low subsonic wind tunnel AF100. This paper also documents the effect of high and low angle of attack on the flow behaviour over an airfoil.
Virtual Shaping of a Two-dimensional NACA 0015 Airfoil Using Synthetic Jet Actuator

NASA Technical Reports Server (NTRS)

Chen, Fang-Jenq; Beeler, George B.

2002-01-01

The Aircraft Morphing Program at NASA Langley envisions an aircraft without conventional control surfaces. Instead of moving control surfaces, the vehicle control systems may be implemented with a combination of propulsive forces, micro surface effectors, and fluidic devices dynamically operated by an intelligent flight control system to provide aircraft maneuverability over each mission segment. As a part of this program, a two-dimensional NACA 0015 airfoil model was designed to test mild maneuvering capability of synthetic jets in a subsonic wind tunnel. The objective of the experiments is to assess the applicability of using unsteady suction and blowing to alter the aerodynamic shape of an airfoil with a purpose to enhance lift and/or to reduce drag. Synthetic jet actuation at different chordwise locations, different forcing frequencies and amplitudes, under different freestream velocities are investigated. The effect of virtual shape change is indicated by a localized increase of surface pressure in the neighborhood of synthetic jet actuation. That causes a negative lift to the airfoil with an upper surface actuation. When actuation is applied near the airfoil leading edge, it appears that the stagnation line is shifted inducing an effect similar to that caused by a small angle of attack to produce an overall lift change.
Laser velocimeter measurements of dynamic stall. [conducted in the Ames two foot wind tunnel

NASA Technical Reports Server (NTRS)

Owen, F. K.

1984-01-01

Laser velocimeter measurements were made during the study of a two-dimensional NACA 0012 airfoil undergoing conditions of dynamic stall. The measurements, which were obtained in the Ames 2 foot wind tunnel at reduced frequencies of 0.12 and 1.2, show significant flow field hysteresis around the static stall angle. Comparisons were also made with dual-plate interferograms and good agreement was found for the attached flow cases. For separated flow, characteristic vortex shedding caused poor agreement and significantly increased the measured Reynolds shear stresses.
Performance evaluation of Space Shuttle SRB parachutes from air drop and scaled model wind tunnel tests. [Solid Rocket Booster recovery system

NASA Technical Reports Server (NTRS)

Moog, R. D.; Bacchus, D. L.; Utreja, L. R.

1979-01-01

The aerodynamic performance characteristics have been determined for the Space Shuttle Solid Rocket Booster drogue, main, and pilot parachutes. The performance evaluation on the 20-degree conical ribbon parachutes is based primarily on air drop tests of full scale prototype parachutes. In addition, parametric wind tunnel tests were performed and used in parachute configuration development and preliminary performance assessments. The wind tunnel test data are compared to the drop test results and both sets of data are used to determine the predicted performance of the Solid Rocket Booster flight parachutes. Data from other drop tests of large ribbon parachutes are also compared with the Solid Rocket Booster parachute performance characteristics. Parameters assessed include full open terminal drag coefficients, reefed drag area, opening characteristics, clustering effects, and forebody interference.
Small-scale Pressure-balanced Structures Driven by Oblique Slow Mode Waves Measured in the Solar Wind

NASA Astrophysics Data System (ADS)

Yao, Shuo; He, J.-S.; Tu, C.-Y.; Wang, L.-H.; Marsch, E.

2013-09-01

Recently, small-scale pressure-balanced structures (PBSs) were identified in the solar wind, but their formation mechanism remains unclear. This work aims to reveal the dependence of the properties of small-scale PBSs on the background magnetic field (B 0) direction and thus to corroborate the in situ mechanism that forms them. We analyze the plasma and magnetic field data obtained by WIND in the quiet solar wind at 1 AU. First, we use a developed moving-average method to obtain B 0(s, t) for every temporal scale (s) at each time moment (t). By wavelet cross-coherence analysis, we obtain the correlation coefficients between the thermal pressure P th and the magnetic pressure P B, distributing against the temporal scale and the angle θxB between B 0(s, t) and Geocentric Solar Ecliptic coordinates (GSE)-x. We note that the angle coverage of a PBS decreases with shorter temporal scale, but the occurrence of the PBSs is independent of θxB. Suspecting that the isolated small PBSs are formed by compressive waves in situ, we continue this study by testing the wave modes forming a small-scale PBS with B 0(s, t) quasi-parallel to GSE-x. As a result, we identify that the cross-helicity and the compressibility attain values for a slow mode from theoretical calculations. The wave vector is derived from minimum variance analysis. Besides, the proton temperatures obey T < T ∥ derived from the velocity distribution functions, excluding a mirror mode, which is the other candidate for the formation of PBSs in situ. Thus, a small-scale PBS is shown to be driven by oblique, slow-mode waves in the solar wind.
Na+/Ca2+ exchange and Na+/K+-ATPase in the heart

PubMed Central

Shattock, Michael J; Ottolia, Michela; Bers, Donald M; Blaustein, Mordecai P; Boguslavskyi, Andrii; Bossuyt, Julie; Bridge, John H B; Chen-Izu, Ye; Clancy, Colleen E; Edwards, Andrew; Goldhaber, Joshua; Kaplan, Jack; Lingrel, Jerry B; Pavlovic, Davor; Philipson, Kenneth; Sipido, Karin R; Xie, Zi-Jian

2015-01-01

This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field. PMID:25772291
Low-speed wind-tunnel tests of a one-tenth-scale model of a blended-arrow advanced supersonic transport. [conducted in Langley full-scale tunnel

NASA Technical Reports Server (NTRS)

Lemore, H. C.; Parett, L. P.

1975-01-01

Tests were conducted in the Langley full scale tunnel to determine the low-speed aerodynamic characteristics of a 1/10 scale model of a blended-arrow advanced supersonic transport. Tests were made for the clean configuration and a high-lift configuration with several combinations of leading- and trailing-edge flaps deflected for providing improved lift and longitudinal stability in the landing and takeoff modes. The tests were conducted for a range of angles of attack from about -6 deg to 30 deg, sideslip angles from -5 deg to 10 deg, and for Reynolds numbers from 6.78 x 1,000,000 to 13.85 x 1,000,000 corresponding to test velocities of 41 knots to 85 knots, respectively.
Research at NASA's NFAC wind tunnels

NASA Technical Reports Server (NTRS)

Edenborough, H. Kipling

1990-01-01

The National Full-Scale Aerodynamics Complex (NFAC) is a unique combination of wind tunnels that allow the testing of aerodynamic and dynamic models at full or large scale. It can even accommodate actual aircraft with their engines running. Maintaining full-scale Reynolds numbers and testing with surface irregularities, protuberances, and control surface gaps that either closely match the full-scale or indeed are those of the full-scale aircraft help produce test data that accurately predict what can be expected from future flight investigations. This complex has grown from the venerable 40- by 80-ft wind tunnel that has served for over 40 years helping researchers obtain data to better understand the aerodynamics of a wide range of aircraft from helicopters to the space shuttle. A recent modification to the tunnel expanded its maximum speed capabilities, added a new 80- by 120-ft test section and provided extensive acoustic treatment. The modification is certain to make the NFAC an even more useful facility for NASA's ongoing research activities. A brief background is presented on the original facility and the kind of testing that has been accomplished using it through the years. A summary of the modification project and the measured capabilities of the two test sections is followed by a review of recent testing activities and of research projected for the future.
Resume and analysis of NACA lateral control research

NASA Technical Reports Server (NTRS)

Weick, Fred E; Jones, Robert T

1937-01-01

An analysis of the principal results of recent NACA lateral control research is made by utilizing the experience and progress gained during the course of the investigation. Two things are considered of primary importance in judging the effectiveness of different control devices: the (calculated) banking and yawing motion of a typical small airplane caused by a deflection of the control, and the stick force required to produce this deflection. The report includes a table in which a number of different lateral control devices are compared on these bases.
Massive star winds interacting with magnetic fields on various scales

NASA Astrophysics Data System (ADS)

David-Uraz, A.; Petit, V.; Erba, C.; Fullerton, A.; Walborn, N.; MacInnis, R.

2018-01-01

One of the defining processes which govern massive star evolution is their continuous mass loss via dense, supersonic line-driven winds. In the case of those OB stars which also host a surface magnetic field, the interaction between that field and the ionized outflow leads to complex circumstellar structures known as magnetospheres. In this contribution, we review recent developments in the field of massive star magnetospheres, including current efforts to characterize the largest magnetosphere surrounding an O star: that of NGC 1624-2. We also discuss the potential of the "analytic dynamical magnetosphere" (ADM) model to interpret multi-wavelength observations. Finally, we examine the possible effects of — heretofore undetected — small-scale magnetic fields on massive star winds and compare their hypothetical consequences to existing, unexplained observations.
A76-0634. 1/50 Scale Model Of The 80X120 Foot Wind Tunnel Model (Nfac) In The Test Section Of The 40X80 Foot Wind Tunnel.

NASA Image and Video Library

1996-06-27

(03/12/1976) 1/50 scale model of the 80x120 foot wind tunnel model (NFAC) in the test section of the 40x80 foot wind tunnel. Model mounted on a rotating ground board designed for this test, viewed from the west, oriented for North wind.
Multi-scale analysis of compressible fluctuations in the solar wind

NASA Astrophysics Data System (ADS)

Roberts, Owen W.; Narita, Yasuhito; Escoubet, C.-Philippe

2018-01-01

Compressible plasma turbulence is investigated in the fast solar wind at proton kinetic scales by the combined use of electron density and magnetic field measurements. Both the scale-dependent cross-correlation (CC) and the reduced magnetic helicity (σm) are used in tandem to determine the properties of the compressible fluctuations at proton kinetic scales. At inertial scales the turbulence is hypothesised to contain a mixture of Alfvénic and slow waves, characterised by weak magnetic helicity and anti-correlation between magnetic field strength B and electron density ne. At proton kinetic scales the observations suggest that the fluctuations have stronger positive magnetic helicities as well as strong anti-correlations within the frequency range studied. These results are interpreted as being characteristic of either counter-propagating kinetic Alfvén wave packets or a mixture of anti-sunward kinetic Alfvén waves along with a component of kinetic slow waves.
SPF Full-scale emissions test method development status ...

EPA Pesticide Factsheets

This is a non-technical presentation that is intended to inform ASTM task group members about our intended approach to full-scale emissions testing that includes the application of spray foam in an environmental chamber. The presentation describes the approach to emissions characterization, types of measurement systems employed, and expected outcomes from the planned tests. Purpose of this presentation is to update the ASTM D22.05 work group regarding status of our full-scale emissions test method development.
Full-scale results for TAM limestone injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baer, S.

1996-12-31

Information is outlined on the use of thermally active marble (TAM) sorbents in boilers. Data are presented on: the comparison of TAM to limestone; NOVACON process development history; CFB test history; CFB pilot scale test; full-scale CFB trial; August, 1996 CFB demonstration; Foster Wheeler Mount Carmel sorbent feed rate comparison and Ca:S comparison; unburned carbon is ash; and advantages and savings in CFB boilers.
RSRA sixth scale wind tunnel test. [of scale model of Sikorsky Whirlwind Helicopter

NASA Technical Reports Server (NTRS)

Flemming, R.; Ruddell, A.

1974-01-01

The sixth scale model of the Sikorsky/NASA/Army rotor systems research aircraft was tested in an 18-foot section of a large subsonic wind tunnel for the purpose of obtaining basic data in the areas of performance, stability, and body surface loads. The model was mounted in the tunnel on the struts arranged in tandem. Basic testing was limited to forward flight with angles of yaw from -20 to +20 degrees and angles of attack from -20 to +25 degrees. Tunnel test speeds were varied up to 172 knots (q = 96 psf). Test data were monitored through a high speed static data acquisition system, linked to a PDP-6 computer. This system provided immediate records of angle of attack, angle of yaw, six component force and moment data, and static and total pressure information. The wind tunnel model was constructed of aluminum structural members with aluminum, fiberglass, and wood skins. Tabulated force and moment data, flow visualization photographs, tabulated surface pressure data are presented for the basic helicopter and compound configurations. Limited discussions of the results of the test are included.
The NACA High-Speed Motion-Picture Camera Optical Compensation at 40,000 Photographs Per Second

NASA Technical Reports Server (NTRS)

Miller, Cearcy D

1946-01-01

The principle of operation of the NACA high-speed camera is completely explained. This camera, operating at the rate of 40,000 photographs per second, took the photographs presented in numerous NACA reports concerning combustion, preignition, and knock in the spark-ignition engine. Many design details are presented and discussed, details of an entirely conventional nature are omitted. The inherent aberrations of the camera are discussed and partly evaluated. The focal-plane-shutter effect of the camera is explained. Photographs of the camera are presented. Some high-speed motion pictures of familiar objects -- photoflash bulb, firecrackers, camera shutter -- are reproduced as an illustration of the quality of the photographs taken by the camera.
Review of Flight Tests of NACA C and D Cowlings on the XP-42 Airplane

NASA Technical Reports Server (NTRS)

Johnston, J Ford

1943-01-01

Results of flight tests of the performance and cooling characteristics of three NACA D cowlings and of a conventional NACA D cowling on the XP-42 airplane are summarized and compared. The D cowling is, in general, characterized by the use of an annular inlet and diffuser section for the engine-cooling air. The D cowlings tested were a long-nose high-inlet-velocity cowling, a short-nose high-inlet-velocity cowling, and a short-nose low inlet-velocity cowling. The use of wide-chord propeller cuffs or an axial-flow fan with the D cowlings increased the cooling pressure recoveries in the climb condition at the expense of some of the improvement in speed.
Large-scale solar wind flow around Saturn's nonaxisymmetric magnetosphere

NASA Astrophysics Data System (ADS)

Sulaiman, A. H.; Jia, X.; Achilleos, N.; Sergis, N.; Gurnett, D. A.; Kurth, W. S.

2017-09-01

The interaction between the solar wind and a magnetosphere is central to the dynamics of a planetary system. Here we address fundamental questions on the large-scale magnetosheath flow around Saturn using a 3-D magnetohydrodynamic (MHD) simulation. We find Saturn's polar-flattened magnetosphere to channel 20% more flow over the poles than around the flanks at the terminator. Further, we decompose the MHD forces responsible for accelerating the magnetosheath plasma to find the plasma pressure gradient as the dominant driver. This is by virtue of a high-β magnetosheath and, in turn, the high-MA bow shock. Together with long-term magnetosheath data by the Cassini spacecraft, we present evidence of how nonaxisymmetry substantially alters the conditions further downstream at the magnetopause, crucial for understanding solar wind-magnetosphere interactions such as reconnection and shear flow-driven instabilities. We anticipate our results to provide a more accurate insight into the global conditions upstream of Saturn and the outer planets.
JWST Full-Scale Model on Display in Germany

NASA Image and Video Library

2010-03-10

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Munich, Germany Credit: EADS Astrium

JWST Full-Scale Model on Display in Germany

NASA Image and Video Library

2017-12-08

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Munich, Germany Credit: EADS Astrium
Hot-bench simulation of the active flexible wing wind-tunnel model

NASA Technical Reports Server (NTRS)

Buttrill, Carey S.; Houck, Jacob A.

1990-01-01

Two simulations, one batch and one real-time, of an aeroelastically-scaled wind-tunnel model were developed. The wind-tunnel model was a full-span, free-to-roll model of an advanced fighter concept. The batch simulation was used to generate and verify the real-time simulation and to test candidate control laws prior to implementation. The real-time simulation supported hot-bench testing of a digital controller, which was developed to actively control the elastic deformation of the wind-tunnel model. Time scaling was required for hot-bench testing. The wind-tunnel model, the mathematical models for the simulations, the techniques employed to reduce the hot-bench time-scale factors, and the verification procedures are described.
Data Recording Room in the 10-by 10-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1973-04-21

The test data recording equipment located in the office building of the 10-by 10-Foot Supersonic Wind Tunnel at the NASA Lewis Research Center. The data system was the state of the art when the facility began operating in 1955 and was upgraded over time. NASA engineers used solenoid valves to measure pressures from different locations within the test section. Up 48 measurements could be fed into a single transducer. The 10-by 10 data recorders could handle up to 200 data channels at once. The Central Automatic Digital Data Encoder (CADDE) converted this direct current raw data from the test section into digital format on magnetic tape. The digital information was sent to the Lewis Central Computer Facility for additional processing. It could also be displayed in the control room via strip charts or oscillographs. The 16-by 56-foot long ERA 1103 UNIVAC mainframe computer processed most of the digital data. The paper tape with the raw data was fed into the ERA 1103 which performed the needed calculations. The information was then sent back to the control room. There was a lag of several minutes before the computed information was available, but it was exponentially faster than the hand calculations performed by the female computers. The 10- by 10-foot tunnel, which had its official opening in May 1956, was built under the Congressional Unitary Plan Act which coordinated wind tunnel construction at the NACA, Air Force, industry, and universities. The 10- by 10 was the largest of the three NACA tunnels built under the act.
Measurement of Vibrations from the 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1950-07-21

Reverend Henry Birkenhauer and E.F. Carome measure ground vibrations on West 220th Street caused by the operation of the 8- by 6-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The 8- by 6 was the laboratory’s first large supersonic wind tunnel. It was also the NACA’s most powerful supersonic tunnel, and the NACA’s first facility capable of running an engine at supersonic speeds. The 8- by 6 was originally an open-throat and non-return tunnel. This meant that the supersonic air flow was blown through the test section and out the other end into the atmosphere. Complaints from the local community led to the installation of a muffler at the tunnel exit and the eventual addition of a return leg. Reverend Brikenhauer, a seismologist, and Carome, an electrical technician were brought in from John Carroll University to take vibration measurements during the 8- by 6 tunnel’s first run with a supersonic engine. They found that the majority of the vibrations came from the air and not the ground. The tunnel’s original muffler offered some relief during the facility checkout runs, but it proved inadequate during the operation of an engine in the test section. Tunnel operation was suspended until a new muffler was designed and installed. The NACA researchers, however, were pleased with the tunnel’s operation. They claimed it was the first time a jet engine was operated in an airflow faster than Mach 2.
Scaling Laws in Canopy Flows: A Wind-Tunnel Analysis

NASA Astrophysics Data System (ADS)

Segalini, Antonio; Fransson, Jens H. M.; Alfredsson, P. Henrik

2013-08-01

An analysis of velocity statistics and spectra measured above a wind-tunnel forest model is reported. Several measurement stations downstream of the forest edge have been investigated and it is observed that, while the mean velocity profile adjusts quickly to the new canopy boundary condition, the turbulence lags behind and shows a continuous penetration towards the free stream along the canopy model. The statistical profiles illustrate this growth and do not collapse when plotted as a function of the vertical coordinate. However, when the statistics are plotted as function of the local mean velocity (normalized with a characteristic velocity scale), they do collapse, independently of the streamwise position and freestream velocity. A new scaling for the spectra of all three velocity components is proposed based on the velocity variance and integral time scale. This normalization improves the collapse of the spectra compared to existing scalings adopted in atmospheric measurements, and allows the determination of a universal function that provides the velocity spectrum. Furthermore, a comparison of the proposed scaling laws for two different canopy densities is shown, demonstrating that the vertical velocity variance is the most sensible statistical quantity to the characteristics of the canopy roughness.
TSA - A Two Scale Approximation for Wind-Generated Ocean Surface Waves

DTIC Science & Technology

2012-09-30

broad-scale version of TSA, or ‘ dTSA ’. In this manner dTSA is able to respond to changing wind situations. Results were shown to compare well with ‘exact...We also implemented the revised version of TSA, denoted ‘ dTSA ’, in WW3 for tests with a storm case, hurricane Juan, which made landfall as a...manner in which the broad-scale of TSA was defined, developing ‘ dTSA ’ as described above, so that in complicated rapidly changing wave spectra cases, a
Bacterial communities in full-scale wastewater treatment systems.

PubMed

Cydzik-Kwiatkowska, Agnieszka; Zielińska, Magdalena

2016-04-01

Bacterial metabolism determines the effectiveness of biological treatment of wastewater. Therefore, it is important to define the relations between the species structure and the performance of full-scale installations. Although there is much laboratory data on microbial consortia, our understanding of dependencies between the microbial structure and operational parameters of full-scale wastewater treatment plants (WWTP) is limited. This mini-review presents the types of microbial consortia in WWTP. Information is given on extracellular polymeric substances production as factor that is key for formation of spatial structures of microorganisms. Additionally, we discuss data on microbial groups including nitrifiers, denitrifiers, Anammox bacteria, and phosphate- and glycogen-accumulating bacteria in full-scale aerobic systems that was obtained with the use of molecular techniques, including high-throughput sequencing, to shed light on dependencies between the microbial ecology of biomass and the overall efficiency and functional stability of wastewater treatment systems. Sludge bulking in WWTPs is addressed, as well as the microbial composition of consortia involved in antibiotic and micropollutant removal.
Kinetic scale turbulence and dissipation in the solar wind: key observational results and future outlook.

PubMed

Goldstein, M L; Wicks, R T; Perri, S; Sahraoui, F

2015-05-13

Turbulence is ubiquitous in the solar wind. Turbulence causes kinetic and magnetic energy to cascade to small scales where they are eventually dissipated, adding heat to the plasma. The details of how this occurs are not well understood. This article reviews the evidence for turbulent dissipation and examines various diagnostics for identifying solar wind regions where dissipation is occurring. We also discuss how future missions will further enhance our understanding of the importance of turbulence to solar wind dynamics. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
Plasma-field Coupling at Small Length Scales in Solar Wind Near 1 AU

NASA Astrophysics Data System (ADS)

Livadiotis, G.; Desai, M. I.

2016-10-01

In collisionless plasmas such as the solar wind, the coupling between plasma constituents and the embedded magnetic field occurs on various temporal and spatial scales, and is primarily responsible for the transfer of energy between waves and particles. Recently, it was shown that the transfer of energy between solar wind plasma particles and waves is governed by a new and unique relationship: the ratio between the magnetosonic energy and the plasma frequency is constant, E ms/ω pl ˜ ℏ*. This paper examines the variability and substantial departure of this ratio from ℏ* observed at ˜1 au, which is caused by a dispersion of fast magnetosonic (FMS) waves. In contrast to the efficiently transferred energy in the fast solar wind, the lower efficiency of the slow solar wind can be caused by this dispersion, whose relation and characteristics are derived and studied. In summary, we show that (I) the ratio E ms/ω pl transitions continuously from the slow to the fast solar wind, tending toward the constant ℏ* (II) the transition is more efficient for larger thermal, Alfvén, or FMS speeds; (III) the fast solar wind is almost dispersionless, characterized by quasi-constant values of the FMS speed, while the slow wind is subject to dispersion that is less effective for larger wind or magnetosonic speeds; and (IV) the constant ℏ* is estimated with the best known precision, ℏ* ≈ (1.160 ± 0.083) × 10-22 Js.
FAST Modularization Framework for Wind Turbine Simulation: Full-System Linearization

DOE PAGES

Jonkman, Jason M.; Jonkman, Bonnie J.

2016-10-03

The wind engineering community relies on multiphysics engineering software to run nonlinear time-domain simulations e.g. for design-standards-based loads analysis. Although most physics involved in wind energy are nonlinear, linearization of the underlying nonlinear system equations is often advantageous to understand the system response and exploit well-established methods and tools for analyzing linear systems. Here, this paper presents the development and verification of the new linearization functionality of the open-source engineering tool FAST v8 for land-based wind turbines, as well as the concepts and mathematical background needed to understand and apply it correctly.
FAST modularization framework for wind turbine simulation: full-system linearization

NASA Astrophysics Data System (ADS)

Jonkman, J. M.; Jonkman, B. J.

2016-09-01

The wind engineering community relies on multiphysics engineering software to run nonlinear time-domain simulations e.g. for design-standards-based loads analysis. Although most physics involved in wind energy are nonlinear, linearization of the underlying nonlinear system equations is often advantageous to understand the system response and exploit well- established methods and tools for analyzing linear systems. This paper presents the development and verification of the new linearization functionality of the open-source engineering tool FAST v8 for land-based wind turbines, as well as the concepts and mathematical background needed to understand and apply it correctly.
Investigation of a Systematic Group of NACA 1-Series Cowlings with and Without Spinners

NASA Technical Reports Server (NTRS)

Nichols, Mark R; Keith, Arvid L , Jr

1949-01-01

Report presents the results of an investigation conducted in the Langley propeller research tunnel to study cowling-spinner combinations based on the NACA 1-series nose inlets and to obtain systematic design data for one family of approximately ellipsoidal spinners. In the main part of the investigation, 11 of the related spinners were tested in various combinations with 9 NACA open-nose cowlings, which were also tested without spinners. The effects of location and shape of the spinner, shape of the inner surface of the cowling lip, and operation of a propeller having approximately oval shanks were investigated briefly. In addition, a study was conducted to determine the correct procedure for extrapolating design conditions determined from the low-speed test data to the design conditions at the actual flight Mach number.
Dynamical downscaling of wind fields for wind power applications

NASA Astrophysics Data System (ADS)

Mengelkamp, H.-T.; Huneke, S.; Geyer, J.

2010-09-01

Dynamical downscaling of wind fields for wind power applications H.-T. Mengelkamp*,**, S. Huneke**, J, Geyer** *GKSS Research Center Geesthacht GmbH **anemos Gesellschaft für Umweltmeteorologie mbH Investments in wind power require information on the long-term mean wind potential and its temporal variations on daily to annual and decadal time scales. This information is rarely available at specific wind farm sites. Short-term on-site measurements usually are only performed over a 12 months period. These data have to be set into the long-term perspective through correlation to long-term consistent wind data sets. Preliminary wind information is often asked for to select favourable wind sites over regional and country wide scales. Lack of high-quality wind measurements at weather stations was the motivation to start high resolution wind field simulations The simulations are basically a refinement of global scale reanalysis data by means of high resolution simulations with an atmospheric mesoscale model using high-resolution terrain and land-use data. The 3-dimensional representation of the atmospheric state available every six hours at 2.5 degree resolution over the globe, known as NCAR/NCEP reanalysis data, forms the boundary conditions for continuous simulations with the non-hydrostatic atmospheric mesoscale model MM5. MM5 is nested in itself down to a horizontal resolution of 5 x 5 km². The simulation is performed for different European countries and covers the period 2000 to present and is continuously updated. Model variables are stored every 10 minutes for various heights. We have analysed the wind field primarily. The wind data set is consistent in space and time and provides information on the regional distribution of the long-term mean wind potential, the temporal variability of the wind potential, the vertical variation of the wind potential, and the temperature, and pressure distribution (air density). In the context of wind power these data are used �
ANEMOS: Development of a next generation wind power forecasting system for the large-scale integration of onshore and offshore wind farms.

NASA Astrophysics Data System (ADS)

Kariniotakis, G.; Anemos Team

2003-04-01

Objectives: Accurate forecasting of the wind energy production up to two days ahead is recognized as a major contribution for reliable large-scale wind power integration. Especially, in a liberalized electricity market, prediction tools enhance the position of wind energy compared to other forms of dispatchable generation. ANEMOS, is a new 3.5 years R&D project supported by the European Commission, that resembles research organizations and end-users with an important experience on the domain. The project aims to develop advanced forecasting models that will substantially outperform current methods. Emphasis is given to situations like complex terrain, extreme weather conditions, as well as to offshore prediction for which no specific tools currently exist. The prediction models will be implemented in a software platform and installed for online operation at onshore and offshore wind farms by the end-users participating in the project. Approach: The paper presents the methodology of the project. Initially, the prediction requirements are identified according to the profiles of the end-users. The project develops prediction models based on both a physical and an alternative statistical approach. Research on physical models gives emphasis to techniques for use in complex terrain and the development of prediction tools based on CFD techniques, advanced model output statistics or high-resolution meteorological information. Statistical models (i.e. based on artificial intelligence) are developed for downscaling, power curve representation, upscaling for prediction at regional or national level, etc. A benchmarking process is set-up to evaluate the performance of the developed models and to compare them with existing ones using a number of case studies. The synergy between statistical and physical approaches is examined to identify promising areas for further improvement of forecasting accuracy. Appropriate physical and statistical prediction models are also developed for
Improving Large-Scale Testing Capability by Modifying the 40- by 80-ft Wind Tunnel

NASA Technical Reports Server (NTRS)

Mort, Kenneth W.; Soderman, Paul T.; Eckert, William T.

1979-01-01

Interagency studies conducted during the last several years have indicated the need to Improve full-scale testing capabilities. The studies showed that the most effective trade between test capability and facility cost was provided by re-powering the existing Ames Research Center 40- by 80-ft Wind Tunnel to Increase the maximum speed from about 100 m/s (200 knots) lo about 150 m/s (300 knots) and by adding a new 24- by 37-m (80- by 120-ft) test section powered for about a 50-m/s (100-knot) maximum speed. This paper reviews the design of the facility, a few or its capabilities, and some of its unique features.
JWST Full-Scale Model on Display at GSFC

NASA Image and Video Library

2010-02-26

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Greenbelt, MD at the NASA Goddard Space Flight Center. Credit: NASA/Goddard Space Flight Center/Pat Izzo
Wake flow control using a dynamically controlled wind turbine

NASA Astrophysics Data System (ADS)

Castillo, Ricardo; Wang, Yeqin; Pol, Suhas; Swift, Andy; Hussain, Fazle; Westergaard, Carsten; Texas Tech University Team

2016-11-01

A wind tunnel based "Hyper Accelerated Wind Farm Kinematic-Control Simulator" (HAWKS) is being built at Texas Tech University to emulate controlled wind turbine flow physics. The HAWKS model turbine has pitch, yaw and speed control which is operated in real model time, similar to that of an equivalent full scale turbine. Also, similar to that of a full scale wind turbine, the controls are developed in a Matlab Simulink environment. The current diagnostic system consists of power, rotor position, rotor speed measurements and PIV wake characterization with four cameras. The setup allows up to 7D downstream of the rotor to be mapped. The purpose of HAWKS is to simulate control strategies at turnaround times much faster than CFD and full scale testing. The fundamental building blocks of the simulator have been tested, and demonstrate wake steering for both static and dynamic turbine actuation. Parameters which have been studied are yaw, rotor speed and combinations hereof. The measured wake deflections for static yaw cases are in agreement with previously reported research implying general applicability of the HAWKS platform for the purpose of manipulating the wake. In this presentation the general results will be introduced followed by an analysis of the wake turbulence and coherent structures when comparing static and dynamic flow cases. The outcome of such studies could ultimately support effective wind farm wake flow control strategies. Texas Emerging Technology Fund (ETF).
Altitude Wind Tunnel Investigation of XJ34-WE-32 Engine Performance Without Electronic Control

NASA Technical Reports Server (NTRS)

Bloomer, Harry E; Walker, William J; Pantages, George L

1953-01-01

An investigation was conducted in the NACA Lewis altitude wind tunnel to evaluate the performance characteristics of an XJ34-WE-32 turbojet engine which was equipped with an afterburner, a variable-area exhaust nozzle, and an integrated electronic control. The data were obtained with the afterburner and electronic control inoperative. Performance data were obtained at altitudes from 5000 to 55,000 feet and flight Mach numbers from 0.28 to 1.06 for a complete range of operable engine speeds at each of four fixed positions of the variable-area exhaust nozzle.
Wind Tunnel Testing of a 120th Scale Large Civil Tilt-Rotor Model in Airplane and Helicopter Modes

NASA Technical Reports Server (NTRS)

Theodore, Colin R.; Willink, Gina C.; Russell, Carl R.; Amy, Alexander R.; Pete, Ashley E.

2014-01-01

In April 2012 and October 2013, NASA and the U.S. Army jointly conducted a wind tunnel test program examining two notional large tilt rotor designs: NASA's Large Civil Tilt Rotor and the Army's High Efficiency Tilt Rotor. The approximately 6%-scale airframe models (unpowered) were tested without rotors in the U.S. Army 7- by 10-foot wind tunnel at NASA Ames Research Center. Measurements of all six forces and moments acting on the airframe were taken using the wind tunnel scale system. In addition to force and moment measurements, flow visualization using tufts, infrared thermography and oil flow were used to identify flow trajectories, boundary layer transition and areas of flow separation. The purpose of this test was to collect data for the validation of computational fluid dynamics tools, for the development of flight dynamics simulation models, and to validate performance predictions made during conceptual design. This paper focuses on the results for the Large Civil Tilt Rotor model in an airplane mode configuration up to 200 knots of wind tunnel speed. Results are presented with the full airframe model with various wing tip and nacelle configurations, and for a wing-only case also with various wing tip and nacelle configurations. Key results show that the addition of a wing extension outboard of the nacelles produces a significant increase in the lift-to-drag ratio, and interestingly decreases the drag compared to the case where the wing extension is not present. The drag decrease is likely due to complex aerodynamic interactions between the nacelle and wing extension that results in a significant drag benefit.
Wind turbine wake interactions at field scale: An LES study of the SWiFT facility

NASA Astrophysics Data System (ADS)

Yang, Xiaolei; Boomsma, Aaron; Barone, Matthew; Sotiropoulos, Fotis

2014-06-01

The University of Minnesota Virtual Wind Simulator (VWiS) code is employed to simulate turbine/atmosphere interactions in the Scaled Wind Farm Technology (SWiFT) facility developed by Sandia National Laboratories in Lubbock, TX, USA. The facility presently consists of three turbines and the simulations consider the case of wind blowing from South such that two turbines are in the free stream and the third turbine in the direct wake of one upstream turbine with separation of 5 rotor diameters. Large-eddy simulation (LES) on two successively finer grids is carried out to examine the sensitivity of the computed solutions to grid refinement. It is found that the details of the break-up of the tip vortices into small-scale turbulence structures can only be resolved on the finer grid. It is also shown that the power coefficient CP of the downwind turbine predicted on the coarse grid is somewhat higher than that obtained on the fine mesh. On the other hand, the rms (root-mean-square) of the CP fluctuations are nearly the same on both grids, although more small-scale turbulence structures are resolved upwind of the downwind turbine on the finer grid.

Some links on this page may take you to non-federal websites. Their policies may differ from this site.