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Sample records for aerodynamic performance characteristics

  1. Performance characteristics of aerodynamically optimum turbines for wind energy generators

    NASA Technical Reports Server (NTRS)

    Rohrbach, C.; Worobel, R.

    1975-01-01

    This paper presents a brief discussion of the aerodynamic methodology for wind energy generator turbines, an approach to the design of aerodynamically optimum wind turbines covering a broad range of design parameters, some insight on the effect on performance of nonoptimum blade shapes which may represent lower fabrication costs, the annual wind turbine energy for a family of optimum wind turbines, and areas of needed research. On the basis of the investigation, it is concluded that optimum wind turbines show high performance over a wide range of design velocity ratios; that structural requirements impose constraints on blade geometry; that variable pitch wind turbines provide excellent power regulation and that annual energy output is insensitive to design rpm and solidity of optimum wind turbines.

  2. Aerodynamic Characteristics and Glide-Back Performance of Langley Glide-Back Booster

    NASA Technical Reports Server (NTRS)

    Pamadi, Bandu N.; Covell, Peter F.; Tartabini, Paul V.; Murphy, Kelly J.

    2004-01-01

    NASA-Langley Research Center is conducting system level studies on an-house concept of a small launch vehicle to address NASA's needs for rapid deployment of small payloads to Low Earth Orbit. The vehicle concept is a three-stage system with a reusable first stage and expendable upper stages. The reusable first stage booster, which glides back to launch site after staging around Mach 3 is named the Langley Glide-Back Booster (LGBB). This paper discusses the aerodynamic characteristics of the LGBB from subsonic to supersonic speeds, development of the aerodynamic database and application of this database to evaluate the glide back performance of the LGBB. The aerodynamic database was assembled using a combination of wind tunnel test data and engineering level analysis. The glide back performance of the LGBB was evaluated using a trajectory optimization code and subject to constraints on angle of attack, dynamic pressure and normal acceleration.

  3. The influence of vehicle aerodynamic and control response characteristics on driver-vehicle performance

    NASA Technical Reports Server (NTRS)

    Alexandridis, A. A.; Repa, B. S.; Wierwille, W. W.

    1978-01-01

    The effects of changes in understeer, control sensitivity, and location of the lateral aerodynamic center of pressure (c.p.) of a typical passenger car on the driver's opinion and on the performance of the driver-vehicle system were studied in a moving-base driving simulator. Twelve subjects with no prior experience on the simulator and no special driving skills performed regulation tasks in the presence of both random and step wind gusts.

  4. X-34 Vehicle Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Brauckmann, Gregory J.

    1998-01-01

    The X-34, being designed and built by the Orbital Sciences Corporation, is an unmanned sub-orbital vehicle designed to be used as a flying test bed to demonstrate key vehicle and operational technologies applicable to future reusable launch vehicles. The X-34 will be air-launched from an L-1011 carrier aircraft at approximately Mach 0.7 and 38,000 feet altitude, where an onboard engine will accelerate the vehicle to speeds above Mach 7 and altitudes to 250,000 feet. An unpowered entry will follow, including an autonomous landing. The X-34 will demonstrate the ability to fly through inclement weather, land horizontally at a designated site, and have a rapid turn-around capability. A series of wind tunnel tests on scaled models was conducted in four facilities at the NASA Langley Research Center to determine the aerodynamic characteristics of the X-34. Analysis of these test results revealed that longitudinal trim could be achieved throughout the design trajectory. The maximum elevon deflection required to trim was only half of that available, leaving a margin for gust alleviation and aerodynamic coefficient uncertainty. Directional control can be achieved aerodynamically except at combined high Mach numbers and high angles of attack, where reaction control jets must be used. The X-34 landing speed, between 184 and 206 knots, is within the capabilities of the gear and tires, and the vehicle has sufficient rudder authority to control the required 30-knot crosswind.

  5. Aerodynamic and propeller performance characteristics of a propfan-powered, semispan model

    NASA Technical Reports Server (NTRS)

    Levin, Alan D.; Smith, Ronald C.; Wood, Richard D.

    1985-01-01

    A semispan wing/body model with a powered propeller was tested to provide data on a total powerplant installation drag penalty of advanced propfan-powered aircraft. The test objectives were to determine the total power plant installation drag penalty on a representative propfan aircraft; to study the effect of configuration modifications on the installed powerplant drag; and to determine performance characteristics of an advanced design propeller which was mounted on a representative nacelle in the presence of a wing.

  6. Supersonic aerodynamic characteristics of a variable-geometry spacecraft designed for high hypersonic performance

    NASA Technical Reports Server (NTRS)

    Spencer, B., Jr.; Fournier, R. H.

    1973-01-01

    An investigation was made in the high Mach number test section of the Langley Unitary Plan wind tunnel on a variable-geometry high hypersonic performance spacecraft concept at Mach numbers from 2.30 to 4.63. The basic lifting body is designed for hypersonic lift-drag ratio near 3.0. The variable-geometry feature is a single-pivot two-position high wing which is deployed at subsonic speeds to improve vehicle landing characteristics. For the present investigation the wing was maintained in a stowed position, and the effects of horizontal stabilizer dihedral, elevon control effectiveness, and the addition of either a conventional single vertical tail or dorsal-fin-type vertical stabilizers on the longitudinal and lateral-directional stability and control characteristics were studied.

  7. X-33 Hypersonic Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.

    1999-01-01

    Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will design, build, and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604BOO02G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate the aerodynamic flight database for the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. Al these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.

  8. X-33 Hypersonic Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.

    1999-01-01

    Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database i n the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.

  9. X-33 Hypersonic Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.

    1999-01-01

    Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database in the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.

  10. X-33 Hypersonic Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Murphy, Kelly J.; Nowak, Robert J.; Thompson, Richard A.; Hollis, Brian R.; Prabhu, Ramadas K.

    1999-01-01

    Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database in the hypersonic regime, The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.

  11. Aerodynamic performance of centrifugal compressors

    SciTech Connect

    Sayyed, S.

    1981-12-01

    Saving money with an efficient pipeline system design depends on accurately predicting compressor performance and ensuring that it meets the manufacturer's guaranteed levels. When shop testing with the actual gas is impractical, an aerodynamic test can ascertain compressor efficiency, but the accuracy and consistency of data acquisition in such tests is critical. Low test-pressure levels necessitate accounting for the effects of Reynolds number and heat transfer. Moreover, the compressor user and manufacturer must agree on the magnitude of the corrections to be applied to the test data.

  12. Aerodynamic characteristics of French consonants

    NASA Astrophysics Data System (ADS)

    Demolin, Didier; Hassid, Sergio; Soquet, Alain

    2004-05-01

    This paper reports some aerodynamic measurements made on French consonants with a group of ten speakers. Speakers were recorded while saying nonsense words in phrases such as papa, dis papa encore. The nonsense words in the study combined each of the French consonants with three vowels /i, a, u/ to from two syllables words with the first syllable being the same as the second. In addition to the audio signal, recordings were made of the oral airflow, the pressure of the air in the pharynx above the vocal folds and the pressure of the air in the trachea just below the vocal folds. The pharyngeal pressure was recorded via a catheter (i.d. 5 mm) passed through the nose so that its open end could be seen in the pharynx below the uvula. The subglottal pressure was recorded via a tracheal puncture between the first and the second rings of the trachea or between the cricoid cartilage and the first tracheal ring. Results compare subglottal presssure, pharyngeal pressure, and airflow values. Comparisons are made between values obtained with male and female subjects and various types of consonants (voiced versus voiceless at the same place of articulation, stops, fricatives, and nasals).

  13. Supersonic Aerodynamic Characteristics of Blunt Body Trim Tab Configurations

    NASA Technical Reports Server (NTRS)

    Korzun, Ashley M.; Murphy, Kelly J.; Edquist, Karl T.

    2013-01-01

    Trim tabs are aerodynamic control surfaces that can allow an entry vehicle to meet aerodynamic performance requirements while reducing or eliminating the use of ballast mass and providing a capability to modulate the lift-to-drag ratio during entry. Force and moment data were obtained on 38 unique, blunt body trim tab configurations in the NASA Langley Research Center Unitary Plan Wind Tunnel. The data were used to parametrically assess the supersonic aerodynamic performance of trim tabs and to understand the influence of tab area, cant angle, and aspect ratio. Across the range of conditions tested (Mach numbers of 2.5, 3.5, and 4.5; angles of attack from -4deg to +20deg; angles of sideslip from 0deg to +8deg), the effects of varying tab area and tab cant angle were found to be much more significant than effects from varying tab aspect ratio. Aerodynamic characteristics exhibited variation with Mach number and forebody geometry over the range of conditions tested. Overall, the results demonstrate that trim tabs are a viable approach to satisfy aerodynamic performance requirements of blunt body entry vehicles with minimal ballast mass. For a 70deg sphere-cone, a tab with 3% area of the forebody and canted approximately 35deg with no ballast mass was found to give the same trim aerodynamics as a baseline model with ballast mass that was 5% of the total entry mass.

  14. HSR Aerodynamic Performance Status and Challenges

    NASA Technical Reports Server (NTRS)

    Gilbert, William P.; Antani, Tony; Ball, Doug; Calloway, Robert L.; Snyder, Phil

    1999-01-01

    This paper describes HSR (High Speed Research) Aerodynamic Performance Status and Challenges. The topics include: 1) Aero impact on HSR; 2) Goals and Targets; 3) Progress and Status; and 4) Remaining Challenges. This paper is presented in viewgraph form.

  15. Supersonic Aerodynamic Characteristics of Proposed Mars '07 Smart Lander Configurations

    NASA Technical Reports Server (NTRS)

    Murphy, Kelly J.; Horvath, Thomas J.; Erickson, Gary E.; Green, Joseph M.

    2002-01-01

    Supersonic aerodynamic data were obtained for proposed Mars '07 Smart Lander configurations in NASA Langley Research Center's Unitary Plan Wind Tunnel. The primary objective of this test program was to assess the supersonic aerodynamic characteristics of the baseline Smart Lander configuration with and without fixed shelf/tab control surfaces. Data were obtained over a Mach number range of 2.3 to 4.5, at a free stream Reynolds Number of 1 x 10(exp 6) based on body diameter. All configurations were run at angles of attack from -5 to 20 degrees and angles of sideslip of -5 to 5 degrees. These results were complemented with computational fluid dynamic (CFD) predictions to enhance the understanding of experimentally observed aerodynamic trends. Inviscid and viscous full model CFD solutions compared well with experimental results for the baseline and 3 shelf/tab configurations. Over the range tested, Mach number effects were shown to be small on vehicle aerodynamic characteristics. Based on the results from 3 different shelf/tab configurations, a fixed control surface appears to be a feasible concept for meeting aerodynamic performance metrics necessary to satisfy mission requirements.

  16. Aerodynamic characteristics of the HL-20

    NASA Astrophysics Data System (ADS)

    Ware, George M.; Cruz, Christopher I.

    1993-09-01

    Wind tunnel tests were made from subsonic to hypersonic speeds to define the aerodynamic characteristics of the HL-20 lifting-body configuration. The data have been assembled into an aerodynamic database for flight analysis of this proposed vehicle. The wind tunnel data indicates that the model is longitudinally and laterally stable (about a center-of-gravity location of 0.54 body length) over the test range from Mach 20 to 0.3. At hypersonic speeds, the HL-20 model trimmed at a lift/drag (L/D) ratio of 1.4. This value gives the vehicle a crossrange capability similar to that of the space shuttle. At subsonic speeds, the HL-20 has a trimmed L/D ratio of about 3.6. Replacing the flat-plate outboard fins with fins having an airfoil shape increased the maximum subsonic trimmed L/D to 4.2.

  17. Aerodynamic Characteristics of Water Rocket and Stabilization of Flight Trajectory

    NASA Astrophysics Data System (ADS)

    Watanabe, Rikio; Tomita, Nobuyuki; Takemae, Toshiaki

    The aerodynamic characteristics of water rockets are analyzed experimentally by wind tunnel testing. Aerodynamic devices such as vortex generators and dimples are tested and their effectiveness to the flight performance of water rocket is discussed. Attaching vortex generators suppresses the unsteady body fluttering. Dimpling the nose reduces the drag coefficient in high angles of attack. Robust design approach is applied to water rocket design for flight stability and optimum water rocket configuration is determined. Semi-sphere nose is found to be effective for flight stability and it is desirable for the safety of landing point. Stiffed fin attachment is required for fins to work properly as aerodynamic device and it enhances the flight stability of water rockets.

  18. Aerodynamic yawing moment characteristics of bird wings.

    PubMed

    Sachs, Gottfried

    2005-06-21

    The aerodynamic yawing moments due to sideslip are considered for wings of birds. Reference is made to the experience with aircraft wings in order to identify features which are significant for the yawing moment characteristics. Thus, it can be shown that wing sweep, aspect ratio and lift coefficient have a great impact. Focus of the paper is on wing sweep which can considerably increase the yawing moment due to sideslip when compared with unswept wings. There are many birds the wings of which employ sweep. To show the effect of sweep for birds, the aerodynamic characteristics of a gull wing which is considered as a representative example are treated in detail. For this purpose, a sophisticated aerodynamic method is used to compute results of high precision. The yawing moments of the gull wing with respect to the sideslip angle and the lift coefficient are determined. They show a significant level of yaw stability which strongly increases with the lift coefficient. It is particularly high in the lift coefficient region of best gliding flight conditions. In order to make the effect of sweep more perspicuous, a modification of the gull wing employing no sweep is considered for comparison. It turns out that the unswept wing yields yawing moments which are substantially smaller than those of the original gull wing with sweep. Another feature significant for the yawing moment characteristics concerns the fact that sweep is at the outer part of bird wings. By considering the underlying physical mechanism, it is shown that this feature is most important for the efficiency of wing sweep. To sum up, wing sweep provides a primary contribution to the yawing moments. It may be concluded that this is an essential reason why there is sweep in bird wings.

  19. Performance and test section flow characteristics of the National Full-Scale Aerodynamics Complex 80- by 120-Foot Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Zell, Peter T.

    1993-01-01

    Results from the performance and test section flow calibration of the 80- by 120-Foot Wind Tunnel are presented. Measurements indicating the 80- by 120-ft test section flow quality were obtained throughout the tunnel operational envelope and for atmospheric wind speeds up to approximately 20 knots. Tunnel performance characteristics and a dynamic pressure system calibration were also documented during the process of mapping the test section flow field. Experimental results indicate that the test section flow quality is relatively insensitive to dynamic pressure and the level of atmospheric winds experienced during the calibration. The dynamic pressure variation in the test section is within +/-75 percent of the average. The axial turbulence intensity is less than 0.5 percent up to the maximum test section speed of 100 knots, and the vertical and lateral flow angle variations are within +/-5 deg and +/-7 deg, respectively. Atmospheric winds were found to affect the pressure distribution in the test section only at high ratios of wind speed to test section speed.

  20. Aerodynamic Characteristics of Two Waverider-Derived Hypersonic Cruise Configurations

    NASA Technical Reports Server (NTRS)

    Cockrell, Charles E., Jr.; Huebner, Lawrence D.; Finley, Dennis B.

    1996-01-01

    An evaluation was made on the effects of integrating the required aircraft components with hypersonic high-lift configurations known as waveriders to create hypersonic cruise vehicles. Previous studies suggest that waveriders offer advantages in aerodynamic performance and propulsion/airframe integration (PAI) characteristics over conventional non-waverider hypersonic shapes. A wind-tunnel model was developed that integrates vehicle components, including canopies, engine components, and control surfaces, with two pure waverider shapes, both conical-flow-derived waveriders for a design Mach number of 4.0. Experimental data and limited computational fluid dynamics (CFD) solutions were obtained over a Mach number range of 1.6 to 4.63. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is not comparable to that of the pure waverider shapes, but is comparable to previously tested hypersonic models. Both configurations exhibit good lateral-directional stability characteristics.

  1. Subsonic/supersonic aerodynamic characteristics for a tactical supercruiser

    NASA Technical Reports Server (NTRS)

    Capone, F. J.; Bare, E. A.; Hollenback, D.; Hutchison, R.

    1984-01-01

    A series of cooperative NASA-Langley/Boeing experimental investigations have been conducted to determine the aeropropulsive characteristics of an advanced tactical fighter designed for supersonic cruise. These investigations were conducted in the Langley 16-Foot Transonic and Lewis 10 x 10-Foot Supersonic Wind Tunnels at Mach numbers from 0.60 to 2.47. This fighter is a Mach 2.0, 49,000 pound class vehicle that features a close-coupled canard and underwing propulsion units that utilize multifunction two-dimensional exhaust nozzles. Tests were conducted to determine the basic aerodynamic characteristics of the configuration with flow-through nacelles in which the spillage effects of representative inlets were measured. The effects of thrust-induced forces on overall aerodynamic performance were evaluated with a series of multifunction nozzles installed on air-powered nacelles. An axisymmetric nozzle configuration was also tested to obtain comparative aeropropulsive performance. Trim aerodynamic characteristics for the flow-through and powered configurations and the effect of thrust vectoring at subsonic speeds are presented.

  2. Aerodynamic characteristics of airplanes at high angles of attack

    NASA Technical Reports Server (NTRS)

    Chambers, J. R.; Grafton, S. B.

    1977-01-01

    An introduction to, and a broad overiew of, the aerodynamic characteristics of airplanes at high angles of attack are provided. Items include: (1) some important fundamental phenomena which determine the aerodynamic characteristics of airplanes at high angles of attack; (2) static and dynamic aerodynamic characteristics near the stall; (3) aerodynamics of the spin; (4) test techniques used in stall/spin studies; (5) applications of aerodynamic data to problems in flight dynamics in the stall/spin area; and (6) the outlook for future research in the area. Although stalling and spinning are flight dynamic problems of importance to all aircraft, including general aviation aircraft, commercial transports, and military airplanes, emphasis is placed on military configurations and the principle aerodynamic factors which influence the stability and control of such vehicles at high angles of attack.

  3. Upper surface blowing aerodynamic and acoustic characteristics

    NASA Technical Reports Server (NTRS)

    Ryle, D. M., Jr.; Braden, J. A.; Gibson, J. S.

    1977-01-01

    Aerodynamic performance at cruise, and noise effects due to variations in nacelle and wing geometry and mode of operation are studied using small aircraft models that simulate upper surface blowing (USB). At cruise speeds ranging from Mach .50 to Mach .82, the key determinants of drag/thrust penalties are found to be nozzle aspect ratio, boattailing angle, and chordwise position; number of nacelles; and streamlined versus symmetric configuration. Recommendations are made for obtaining favorable cruise configurations. The acoustic studies, which concentrate on the noise created by the jet exhaust flow and its interaction with wing and flap surfaces, isolate several important sources of USB noise, including nozzle shape, exit velocity, and impingement angle; flow pathlength; and flap angle and radius of curvature. Suggestions for lessening noise due to trailing edge flow velocity, flow pathlength, and flow spreading are given, though compromises between some design options may be necessary.

  4. Aerodynamic Characteristics, Database Development and Flight Simulation of the X-34 Vehicle

    NASA Technical Reports Server (NTRS)

    Pamadi, Bandu N.; Brauckmann, Gregory J.; Ruth, Michael J.; Fuhrmann, Henri D.

    2000-01-01

    An overview of the aerodynamic characteristics, development of the preflight aerodynamic database and flight simulation of the NASA/Orbital X-34 vehicle is presented in this paper. To develop the aerodynamic database, wind tunnel tests from subsonic to hypersonic Mach numbers including ground effect tests at low subsonic speeds were conducted in various facilities at the NASA Langley Research Center. Where wind tunnel test data was not available, engineering level analysis is used to fill the gaps in the database. Using this aerodynamic data, simulations have been performed for typical design reference missions of the X-34 vehicle.

  5. Assessment of aerodynamic performance of V/STOL and STOVL fighter aircraft

    NASA Technical Reports Server (NTRS)

    Nelms, W. P.

    1984-01-01

    The aerodynamic performance of V/STOL and STOVL fighter/attack aircraft was assessed. Aerodynamic and propulsion/airframe integration activities are described and small and large scale research programs are considered. Uncertainties affecting aerodynamic performance that are associated with special configuration features resulting from the V/STOL requirement are addressed. Example uncertainties relate to minimum drag, wave drag, high angle of attack characteristics, and power induced effects.

  6. Performance and test section flow characteristics of the National Full-Scale Aerodynamics Complex 40- by 80-foot wind tunnel

    NASA Technical Reports Server (NTRS)

    Zell, Peter T.; Flack, Karen

    1989-01-01

    Results from the performance and test section flow calibration of the 40- by 80-Foot Wind Tunnel are presented. A flow calibration test was conducted in May and June 1987. The goal of the flow calibration test was to determine detailed spatial variations in the 40- by 80-ft test section flow quality throughout the tunnel operational envelope. Data were collected for test section speeds up to 300 knots and for air exchange rates of 0, 5, and 10 percent. The tunnel performance was also calibrated during the detailed mapping of the test section flow field. Experimental results presented indicate that the flow quality in the test section, with the exception of temperature, is relatively insensitive to the level of dynamic pressure and the air exchange rate. The dynamic pressure variation in the test section is within + or - 0.5 deg at all test section velocities. Cross-stream temperature gradients in the test section caused by the air exchange system were documented, and a correction method was established. Streamwise static pressure variation on the centerline is about 1 percent of test section dynamic pressure over 30 ft of the test section length.

  7. Aerodynamics of the Viggen 37 aircraft. Part 1: General characteristics at low speed

    NASA Technical Reports Server (NTRS)

    Karling, K.

    1986-01-01

    A description of the aerodynamics of the Viggen 37 and its performances, especially at low speeds is presented. The aerodynamic requirements for the design of the Viggen 37 aircraft are given, including the basic design, performance requirement, and aerodynamic characteristics, static and dynamic load test results and flight test results. The Viggen 37 aircraft is designed to be used for air attack, surveillance, pursuit, and training applications. It is shown that this aircraft is suitable for short runways, and has good maneuvering, acceleration, and climbing characteristics. The design objectives for this aircraft were met by utilizing the effect produced by the interference between two triangular wings, positioned in tandem.

  8. 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 1; Configuration Aerodynamics

    NASA Technical Reports Server (NTRS)

    Baize, Daniel G. (Editor)

    1999-01-01

    The High-Speed Research Program and NASA Langley Research Center sponsored the NASA High-Speed Research Program Aerodynamic Performance Workshop on February 25-28, 1997. The workshop was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, Flight Controls, Supersonic Laminar Flow Control, and Sonic Boom Prediction. The workshop objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientist and engineers working HSCT aerodynamics. In particular, single- and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT Motion Simulator results were presented along with executive summaries for all the Aerodynamic Performance technology areas.

  9. Performance of an aerodynamic particle separator

    SciTech Connect

    Ragland, K.; Han, J.; Aerts, D.

    1996-12-31

    This compact, high-flow device aerodynamically separates small particles from a gas stream by a series of annular truncated airfoils. The operating concept, design and performance of this novel particle separator are described. Tests results using corn starch and post-cyclone coal fly ash are presented. Particle collection efficiencies of 90% for corn starch and 70% for coal fly ash were measured at inlet velocities of 80 ft s{sup {minus}1} (2,700 cfm) and (6 inches) water pressure drop with particle loading up to 4 gr ft{sup {minus}3} in air at standard conditions. Results from computer modeling using FLUENT are presented and compared to the tests. The aerodynamic particle separator is an attractive alternative to a cyclone collector.

  10. Predicted aerodynamic characteristics for HL-20 lifting-body using the aerodynamic preliminary analysis system (APAS)

    NASA Technical Reports Server (NTRS)

    Cruz, Christopher I.; Ware, George M.

    1992-01-01

    The aerodynamic characteristics of the HL-20 lifting body configuraiton obtained through the APAS and from wind-tunnel tests have been compared. The APAS is considered to be an easy-to-use, relatively simple tool for quick preliminary estimation of vehicle aerodynamics. The APAS estimates are found to be in good agreement with experimental results to be used for preliminary evaluation of the HL-20. The APAS accuracy in predicting aerodynamics of the HL-20 varied over the Mach range. The speed ranges of best agreement were subsonic and hypersonic, while least agreement was in the Mach range from 1.2 to about 2,5.

  11. 1999 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 1; Configuration Aerodynamics

    NASA Technical Reports Server (NTRS)

    Hahne, David E. (Editor)

    1999-01-01

    NASA's High-Speed Research Program sponsored the 1999 Aerodynamic Performance Technical Review on February 8-12, 1999 in Anaheim, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in the areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High Lift, and Flight Controls. The review objectives were to: (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working on HSCT aerodynamics. In particular, single and midpoint optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented, along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program. This Volume 1/Part 1 publication covers configuration aerodynamics.

  12. Techniques for estimating Space Station aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Thomas, Richard E.

    1993-01-01

    A method was devised and calculations were performed to determine the effects of reflected molecules on the aerodynamic force and moment coefficients for a body in free molecule flow. A procedure was developed for determining the velocity and temperature distributions of molecules reflected from a surface of arbitrary momentum and energy accommodation. A system of equations, based on momentum and energy balances for the surface, incident, and reflected molecules, was solved by a numerical optimization technique. The minimization of a 'cost' function, developed from the set of equations, resulted in the determination of the defining properties of the flow reflected from the arbitrary surface. The properties used to define both the incident and reflected flows were: average temperature of the molecules in the flow, angle of the flow with respect to a vector normal to the surface, and the molecular speed ratio. The properties of the reflected flow were used to calculate the contribution of multiply reflected molecules to the force and moments on a test body in the flow. The test configuration consisted of two flat plates joined along one edge at a right angle to each other. When force and moment coefficients of this 90 deg concave wedge were compared to results that did not include multiple reflections, it was found that multiple reflections could nearly double lift and drag coefficients, with nearly a 50 percent increase in pitching moment for cases with specular or nearly specular accommodation. The cases of diffuse or nearly diffuse accommodation often had minor reductions in axial and normal forces when multiple reflections were included. There were several cases of intermediate accommodation where the addition of multiple reflection effects more than tripled the lift coefficient over the convex technique.

  13. Aerodynamic characteristics of flying fish in gliding flight.

    PubMed

    Park, Hyungmin; Choi, Haecheon

    2010-10-01

    The flying fish (family Exocoetidae) is an exceptional marine flying vertebrate, utilizing the advantages of moving in two different media, i.e. swimming in water and flying in air. Despite some physical limitations by moving in both water and air, the flying fish has evolved to have good aerodynamic designs (such as the hypertrophied fins and cylindrical body with a ventrally flattened surface) for proficient gliding flight. Hence, the morphological and behavioral adaptations of flying fish to aerial locomotion have attracted great interest from various fields including biology and aerodynamics. Several aspects of the flight of flying fish have been determined or conjectured from previous field observations and measurements of morphometric parameters. However, the detailed measurement of wing performance associated with its morphometry for identifying the characteristics of flight in flying fish has not been performed yet. Therefore, in the present study, we directly measure the aerodynamic forces and moment on darkedged-wing flying fish (Cypselurus hiraii) models and correlated them with morphological characteristics of wing (fin). The model configurations considered are: (1) both the pectoral and pelvic fins spread out, (2) only the pectoral fins spread with the pelvic fins folded, and (3) both fins folded. The role of the pelvic fins was found to increase the lift force and lift-to-drag ratio, which is confirmed by the jet-like flow structure existing between the pectoral and pelvic fins. With both the pectoral and pelvic fins spread, the longitudinal static stability is also more enhanced than that with the pelvic fins folded. For cases 1 and 2, the lift-to-drag ratio was maximum at attack angles of around 0 deg, where the attack angle is the angle between the longitudinal body axis and the flying direction. The lift coefficient is largest at attack angles around 30∼35 deg, at which the flying fish is observed to emerge from the sea surface. From glide polar

  14. 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 1; Configuration Aerodynamics

    NASA Technical Reports Server (NTRS)

    McMillin, S. Naomi (Editor)

    1999-01-01

    NASA's High-Speed Research Program sponsored the 1998 Aerodynamic Performance Technical Review on February 9-13, in Los Angeles, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, and Flight Controls. The review objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working HSCT aerodynamics. In particular, single and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program.

  15. 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 1; Configuration Aerodynamics

    NASA Technical Reports Server (NTRS)

    McMillin, S. Naomi (Editor)

    1999-01-01

    NASA's High-Speed Research Program sponsored the 1998 Aerodynamic Performance Technical Review on February 9-13, in Los Angeles, California. The review was designed to bring together NASA and industry HighSpeed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of. Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, and Flight Controls. The review objectives were to: (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working HSCT aerodynamics. In particular, single and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program.

  16. 1999 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 1; Configuration Aerodynamics

    NASA Technical Reports Server (NTRS)

    Hahne, David E. (Editor)

    1999-01-01

    NASA's High-Speed Research Program sponsored the 1999 Aerodynamic Performance Technical Review on February 8-12, 1999 in Anaheim, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in the areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High Lift, and Flight Controls. The review objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working on HSCT aerodynamics. In particular, single and midpoint optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented, along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program. This Volume 1/Part 2 publication covers the design optimization and testing sessions.

  17. 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 1; Configuration Aerodynamics

    NASA Technical Reports Server (NTRS)

    Baize, Daniel G. (Editor)

    1999-01-01

    The High-Speed Research Program and NASA Langley Research Center sponsored the NASA High-Speed Research Program Aerodynamic Performance Workshop on February 25-28, 1997. The workshop was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in area of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, Flight Controls, Supersonic Laminar Flow Control, and Sonic Boom Prediction. The workshop objectives were to (1) report the progress and status of HSCT aerodyamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientist and engineers working HSCT aerodynamics. In particular, single- and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT Motion Simulator results were presented along with executive summaries for all the Aerodynamic Performance technology areas.

  18. Aerodynamic characteristics of reentry vehicles at supersonic velocities

    NASA Astrophysics Data System (ADS)

    Adamov, N. P.; Kharitonov, A. M.; Chasovnikov, E. A.; Dyad'kin, A. A.; Kazakov, M. I.; Krylov, A. N.; Skorovarov, A. Yu.

    2015-09-01

    Models of promising reentry vehicles, experimental equipment, and test program are described. The method used to determine the total aerodynamic characteristics of these models on the AB-313 mechanical balance in the T-313 supersonic wind tunnel and the method used for simulations are presented. The aerodynamic coefficients of the examined objects in wide ranges of Mach numbers and angles of attack are obtained. The experimental data are compared with the results of simulations.

  19. High Speed Aerodynamic Characteristics of the GAF0PH Aerofoil

    DTIC Science & Technology

    1980-09-01

    upper surface of the aerofoil for angles of incidence greater than 210. POSTAL ADDRESS: Chief Superintendent, Aeronautical Research Laboratories, Box...kCLAERO-.NOTE3 98 -AR-002-223 -LEVEL m DEPARTMENT OF DEFENCE 00 DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION AERONAUTICAL RESEARCH LABORATORIES...MELBOURNE, VICTORIA AERODYNAMICS NOTE 398 ’,\\ HIGH SPEED AERODYNAMIC CHARACTERISTICS OF THE GAFPH AEROFOIL by ~B D :, . , .IR-© Approved for Public Release

  20. Development of a morphing flap using shape memory alloy actuators: the aerodynamic characteristics of a morphing flap

    NASA Astrophysics Data System (ADS)

    Ko, Seung-Hee; Bae, Jae-Sung; Rho, Jin-Ho

    2014-07-01

    The discontinuous contour of a wing with conventional flaps diminishes the aerodynamic performance of an aircraft. A wing with a continuous contour does not experience extreme flow stream fluctuations during flight, and consequently has good aerodynamic characteristics. In this study, a morphing flap using shape memory alloy actuators is proposed, designed and fabricated, and its aerodynamic characteristics are investigated using aerodynamic analyses and wind tunnel tests. The ribs of the morphing flap are designed and fabricated with multiple elements joined together in a way that allows relative rotations of adjacent elements and forms a smooth contour of the morphing flap. The aerodynamic analyses of this multiple-element morphing-flap wing are performed using XFLR pro; its aerodynamic performance is compared with that of a mechanical-flap wing, and is measured through wind-tunnel tests.

  1. Extended mapping and characteristics techniques for inverse aerodynamic design

    NASA Technical Reports Server (NTRS)

    Sobieczky, H.; Qian, Y. J.

    1991-01-01

    Some ideas for using hodograph theory, mapping techniques and methods of characteristics to formulate typical aerodynamic design boundary value problems are developed. The inverse method of characteristics is shown to be a fast tool for design of transonic flow elements as well as supersonic flows with given shock waves.

  2. Aerodynamic Performance of Missile Configurations at Transonic Speeds Including the Effects of a Jet Plume

    DTIC Science & Technology

    1976-02-18

    speeds. The goal of the entire research project is to develop calculation techniques that allow the aerodynamic characteristics of missile ...Shock attachment angle and Mach number relationship . . II. ANALYSIS OF INVISCID FLOW In order to calculate the aerodynamic performance of missile ...and a change in any part of the flow field affects every other part. Along each characteristic line the dependent variables have to satisfy the

  3. Aerodynamic Characteristic of the Active Compliant Trailing Edge Concept

    NASA Astrophysics Data System (ADS)

    Nie, Rui; Qiu, Jinhao; Ji, Hongli; Li, Dawei

    2016-06-01

    This paper introduces a novel Morphing Wing structure known as the Active Compliant Trailing Edge (ACTE). ACTE structures are designed using the concept of “distributed compliance” and wing skins of ACTE are fabricated from high-strength fiberglass composites laminates. Through the relative sliding between upper and lower wing skins which are connected by a linear guide pairs, the wing is able to achieve a large continuous deformation. In order to present an investigation about aerodynamics and noise characteristics of ACTE, a series of 2D airfoil analyses are established. The aerodynamic characteristics between ACTE and conventional deflection airfoil are analyzed and compared, and the impacts of different ACTE structure design parameters on aerodynamic characteristics are discussed. The airfoils mentioned above include two types (NACA0012 and NACA64A005.92). The computing results demonstrate that: compared with the conventional plane flap airfoil, the morphing wing using ACTE structures has the capability to improve aerodynamic characteristic and flow separation characteristic. In order to study the noise level of ACTE, flow field analysis using LES model is done to provide noise source data, and then the FW-H method is used to get the far field noise levels. The simulation results show that: compared with the conventional flap/aileron airfoil, the ACTE configuration is better to suppress the flow separation and lower the overall sound pressure level.

  4. Aerodynamic Characteristics of Telescopic Aerospikes with Multiple-Row-Disk

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hiroaki; Maru, Yusuke; Sato, Tetsuya

    This paper reports experimental studies on telescopic aerospikes with multiple disks. The telescopic aerospike is useful as an aerodynamic control device; however, changing its length causes a buzz phenomenon, which many researchers have reported. The occurrence of buzzing might be critical to the vehicle because it brings about severe pressure oscillations on the surface. Disks on the shaft produce stable recirculation regions by dividing the single separation flow into several conical cavity flows. The telescopic aerospikes with stabilizer disks are useful without any length constraints. Aerodynamic characteristics of the telescopic aerospikes were investigated through a series of wind tunnel tests. Transition of recirculation/reattachment flow modes of a plain spike causes a large change in the drag coefficient. Because of this hysteresis phenomenon and the buzzing, the plain spike is unsuitable for fine aerodynamic control devices. Adding stabilizer disks is effective for the improved control of aerospikes.

  5. Nozzle and wing geometry effects on OTW aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Vonglahn, U.; Groesbeck, D.

    1976-01-01

    The effects of nozzle geometry and wing size on the aerodynamic performance of several 5:1 aspect ratio slot nozzles are presented for over-the-wing (OTW) configurations. Nozzle geometry variables include roof angle, sidewall cutback, and nozzle chordwise location. Wing variables include chord size, and flap deflection. Several external deflectors also were included for comparison. The data indicate that good flow turning may not necessarily provide the best aerodynamic performance. The results suggest that a variable exhaust nozzle geometry offers the best solution for a viable OTW configuration.

  6. Investigation of Factors Affecting Aerodynamic Performance of Nebulized Nanoemulsion

    PubMed Central

    Kamali, Hosein; Abbasi, Shayan; Amini, Mohammad Ali; Amani, Amir

    2016-01-01

    This work aimed to prepare a nanoemulsion preparation containing budesonide and assess its aerodynamic behavior in comparison with suspension of budesonide. In-vitro aerodynamic performance of the corresponding micellar solution (ie. nanoemulsion preparation without oil) was investigated too. Nanoemulsions of almond oil containing budesonide, as a hydrophobic model drug molecule, were prepared and optimized. Then, the effect of variation of surfactant/co-surfactant concentration on the aerodynamic properties of the nebulized aerosol was studied. The results indicated that the most physically stable formulation makes the smallest aerodynamic size. The concentration of co-surfactant was also shown to be critical in determination of aerodynamic size. Furthermore, the optimized sample, with 3% w/w almond oil, 20% w/w Tween 80+Span 80 and 2% w/w ethanol showed a smaller MMAD in comparison with the commercially available suspension and the micellar solution. PMID:28243265

  7. Aerodynamic Characteristics of Tracheostomy Speaking Valves.

    ERIC Educational Resources Information Center

    Fornataro-Clerici, Lisa; Zajac, David J.

    1993-01-01

    Pressure-flow characteristics were determined for four different one-way valves (Kisner, Montgomery, Olympic, and Passy-Muir) used for speech production in tracheotomy patients. Results indicated significant differences in resistance among the valves, with the resistance of one valve substantially greater than that of the normal upper airways.…

  8. Investigation of aerodynamic characteristics of subsonic wings

    NASA Technical Reports Server (NTRS)

    Dejarnette, F. R.; Frink, N. T.

    1979-01-01

    An analytical strake design procedure is investigated. A numerical solution to the governing strake design equation is used to generate a series of strakes which are tested in a water tunnel to study their vortex breakdown characteristics. The strakes are scaled for use on a half-scale model of the NASA-LaRC general research fuselage with a 44 degrees trapezoidal wing. An analytical solution to the governing design equation is obtained. The strake design procedure relates the potential-flow leading-edge suction and pressure distributions to vortex stability. Several suction distributions are studied and those which are more triangular and peak near the tip generate strakes that reach higher angles of attack before vortex breakdown occurs at the wing trailing edge. For the same suction distribution, a conical rather than three dimensional pressure specification results in a better strake shape as judged from its vortex breakdown characteristics.

  9. Aerodynamic and Aeroelastic Characteristics of a Tension Cone Inflatable Aerodynamic Decelerator

    NASA Technical Reports Server (NTRS)

    Clark, Ian G.; Cruz, Juan R.; Hughes, Monica F.; Ware, Joanne S.; Madlangbayan, Albert; Braun, Robert D.

    2009-01-01

    The supersonic aerodynamic and aeroelastic characteristics of a tension cone inflatable aerodynamic decelerator were investigated by wind tunnel testing. Two sets of tests were conducted: one using rigid models and another using textile models. Tests using rigid models were conducted over a Mach number range from 1.65 to 4.5 at angles of attack from -12 to 20 degrees. The axial, normal, and pitching moment coefficients were found to be insensitive to Mach number over the tested range. The axial force coefficient was nearly constant (C(sub A) = 1.45 +/- 0.05) with respect to angle of attack. Both the normal and pitching moment coefficients were nearly linear with respect to angle of attack. The pitching moment coefficient showed the model to be statically stable about the reference point. Schlieren images and video showed a detached bow shock with no evidence of large regions of separated flow and/or embedded shocks at all Mach numbers investigated. Qualitatively similar static aerodynamic coefficient and flow visualization results were obtained using textile models at a Mach number of 2.5. Using inflatable textile models the torus pressure required to maintain the model in the fully-inflated configuration was determined. This pressure was found to be sensitive to details in the structural configuration of the inflatable models. Additional tests included surface pressure measurements on rigid models and deployment and inflation tests with inflatable models.

  10. Wake shape and its effects on aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Emdad, H.; Lan, C. E.

    1986-01-01

    The wake shape under symmetrical flight conditions and its effects on aerodynamic characteristics are examined. In addition, the effect of wake shape in sideslip and discrete vortices such as strake or forebody vortex on lateral characteristics is presented. The present numerical method for airplane configurations, which is based on discretization of the vortex sheet into vortex segments, verified the symmetrical and asymmetrical roll-up process of the trailing vortices. Also, the effect of wing wake on tail planes is calculated. It is concluded that at high lift the assumption of flat wake for longitudinal and lateral-directional characteristics should be reexamined.

  11. Comparison of aerodynamic characteristics of pentagonal and hexagonal shaped bridge decks

    NASA Astrophysics Data System (ADS)

    Haque, Md. Naimul; Katsuchi, Hiroshi; Yamada, Hitoshi; Nishio, Mayuko

    2016-07-01

    Aerodynamics of the long-span bridge deck should be well understood for an efficient design of the bridge system. For practical bridges various deck shapes are being recommended and adopted, yet not all of their aerodynamic behaviors are well interpreted. In the present study, a numerical investigation was carried out to explore the aerodynamic characteristics of pentagonal and hexagonal shaped bridge decks. A relative comparison of steady state aerodynamic responses was made and the flow field was critically analyzed for better understanding the aerodynamic responses. It was found that the hexagonal shaped bridge deck has better aerodynamic characteristics as compared to the pentagonal shaped bridge deck.

  12. Wind Tunnel Tests on Aerodynamic Characteristics of Advanced Solid Rocket

    NASA Astrophysics Data System (ADS)

    Kitamura, Keiichi; Fujimoto, Keiichiro; Nonaka, Satoshi; Irikado, Tomoko; Fukuzoe, Moriyasu; Shima, Eiji

    The Advanced Solid Rocket is being developed by JAXA (Japan Aerospace Exploration Agency). Since its configuration has been changed very recently, its aerodynamic characteristics are of great interest of the JAXA Advanced Solid Rocket Team. In this study, we carried out wind tunnel tests on the aerodynamic characteristics of the present configuration for Mach 1.5. Six test cases were conducted with different body configurations, attack angles, and roll angles. A six component balance, oilflow visualization, Schlieren images were used throughout the experiments. It was found that, at zero angle-of-attack, the flow around the body were perturbed and its drag (axial force) characteristics were significantly influenced by protruding body components such as flanges, cable ducts, and attitude control units of SMSJ (Solid Motor Side Jet), while the nozzle had a minor role. With angle-of-attack of five degree, normal force of CNα = 3.50±0.03 was measured along with complex flow features observed in the full-component model; whereas no crossflow separations were induced around the no-protuberance model with CNα = 2.58±0.10. These values were almost constant with respect to the angle-of-attack in both of the cases. Furthermore, presence of roll angle made the flow more complicated, involving interactions of separation vortices. These data provide us with fundamental and important aerodynamic insights of the Advanced Solid Rocket, and they will be utilized as reference data for the corresponding numerical analysis.

  13. Effects of Leading Edge Defect on the Aerodynamic and Flow Characteristics of an S809 Airfoil

    PubMed Central

    Wang, Yan; Zheng, Xiaojing; Hu, Ruifeng; Wang, Ping

    2016-01-01

    Background Unexpected performance degradation occurs in wind turbine blades due to leading edge defect when suffering from continuous impacts with rain drops, hails, insects, or solid particles during its operation life. To assess this issue, this paper numerically investigates the steady and dynamic stall characteristics of an S809 airfoil with various leading edge defects. More leading edge defect sizes and much closer to practical parameters are investigated in the paper. Methodology Numerical computation is conducted using the SST k-ω turbulence model, and the method has been validated by comparison with existed published data. In order to ensure the calculation convergence, the residuals for the continuity equation are set to be less than 10−7 and 10−6 in steady state and dynamic stall cases. The simulations are conducted with the software ANSYS Fluent 13.0. Results It is found that the characteristics of aerodynamic coefficients and flow fields are sensitive to leading edge defect both in steady and dynamic conditions. For airfoils with the defect thickness of 6%tc, leading edge defect has a relative small influence on the aerodynamics of S809 airfoil. For other investigated defect thicknesses, leading edge defect has much greater influence on the flow field structures, pressure coefficients and aerodynamic characteristics of airfoil at relative small defect lengths. For example, the lift coefficients decrease and drag coefficients increase sharply after the appearance of leading edge defect. However, the aerodynamic characteristics could reach a constant value when the defect length is large enough. The flow field, pressure coefficient distribution and aerodynamic coefficients do not change a lot when the defect lengths reach to 0.5%c,1%c, 2%c and 3%c with defect thicknesses of 6%tc, 12%tc,18%tc and 25%tc, respectively. In addition, the results also show that the critical defect length/thickness ratio is 0.5, beyond which the aerodynamic characteristics

  14. Aerodynamic Characteristics of Parachutes at Mach Numbers from 1.6 to 3

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Aerodynamic Characteristics of Parachutes at Mach Numbers from 1.6 to 3. A wind-tunnel investigation was conducted to determine the parameters affecting the aerodynamic performance of drogue parachutes in the Mach number range from 1.6 to 3. Flow studies of both rigid and flexible-parachute models were made by means of high-speed schlieren motion pictures and drag coefficients of the flexible-parachute models were measured at simulated altitudes from about 50,000 to 120,000 feet. [Entire movie available on DVD from CASI as Doc ID 20070030970. Contact help@sti.nasa.gov

  15. Aerodynamic Characteristics of High Speed Trains under Cross Wind Conditions

    NASA Astrophysics Data System (ADS)

    Chen, W.; Wu, S. P.; Zhang, Y.

    2011-09-01

    Numerical simulation for the two models in cross-wind was carried out in this paper. The three-dimensional compressible Reynolds-averaged Navier-Stokes equations(RANS), combined with the standard k-ɛ turbulence model, were solved on multi-block hybrid grids by second order upwind finite volume technique. The impact of fairing on aerodynamic characteristics of the train models was analyzed. It is shown that, the flow separates on the fairing and a strong vortex is generated, the pressure on the upper middle car decreases dramatically, which leads to a large lift force. The fairing changes the basic patterns around the trains. In addition, formulas of the coefficient of aerodynamic force at small yaw angles up to 24° were expressed.

  16. Predicting aerodynamic characteristic of typical wind turbine airfoils using CFD

    SciTech Connect

    Wolfe, W.P.; Ochs, S.S.

    1997-09-01

    An investigation was conducted into the capabilities and accuracy of a representative computational fluid dynamics code to predict the flow field and aerodynamic characteristics of typical wind-turbine airfoils. Comparisons of the computed pressure and aerodynamic coefficients were made with wind tunnel data. This work highlights two areas in CFD that require further investigation and development in order to enable accurate numerical simulations of flow about current generation wind-turbine airfoils: transition prediction and turbulence modeling. The results show that the laminar-to turbulent transition point must be modeled correctly to get accurate simulations for attached flow. Calculations also show that the standard turbulence model used in most commercial CFD codes, the k-e model, is not appropriate at angles of attack with flow separation. 14 refs., 28 figs., 4 tabs.

  17. Design and aerodynamic characteristics of a span morphing wing

    NASA Astrophysics Data System (ADS)

    Yu, Yuemin; Liu, Yanju; Leng, Jinsong

    2009-03-01

    Flight vehicles are often designed to function around a primary operating point such as an efficient cruise or a high maneuverability mode. Performance and efficiency deteriorate rapidly as the airplane moves towards other portions of the flight envelope. One solution to this quandary is to radically change the shape of the aircraft. This yields both improved efficiency and a larger flight envelope. This global shape change is an example of morphing aircraft . One concept of morphing is the span morphing wing in which the wingspan is varied to accommodate multiple flight regimes. This type of design allows for at least two discreet modes of the aircraft. The original configuration, in which the extensible portion of the wing is fully retracted, yields a high speed dash mode. Fully extending the wing provides the aircraft with a low speed mode tailored for fine tracking and loiter tasks. This paper discusses the design of a span morphing wing that permits a change in the aspect ratio while simultaneously supporting structural wing loads. The wing cross section is maintained by NACA 4412 rib sections . The span morphing wing was investigated in different configurations. The wing area and the aspect ratio of the span morphing wing increase as the wings pan increases. Computational aerodynamics are used to estimate the performance and dynamic characteristics of each wing shape of this span morphing wing as its wingspan is changed. Results show that in order to obtain the same lift, the conventional wing requires a larger angle of attach(AOA) than that of the span morphing wing.The lift of the span morphing wing increases as the wing span ,Mach number and AOA increases.

  18. Aerodynamic performances of cruise missile flying above local terrain

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Saad, M. R.; Che Idris, A.; Rahman, M. R. A.; Sujipto, S.

    2016-10-01

    Cruise missile can be classified as a smart bomb and also Unmanned Aerial Vehicle (UAV) due to its ability to move and manoeuvre by itself without a pilot. Cruise missile flies in constant velocity in cruising stage. Malaysia is one of the consumers of cruise missiles that are imported from other nations, which can have distinct geographic factors including their local terrains compared to Malaysia. Some of the aerodynamic performances of missile such as drag and lift coefficients can be affected by the local geographic conditions in Malaysia, which is different from the origin nation. Therefore, a detailed study must be done to get aerodynamic performance of cruise missiles that operate in Malaysia. The effect of aerodynamic angles such as angle of attack and side slip can be used to investigate the aerodynamic performances of cruise missile. Hence, subsonic wind tunnel testings were conducted to obtain the aerodynamic performances of the missile at various angle of attack and sideslip angles. Smoke visualization was also performed to visualize the behaviour of flow separation. The optimum angle of attack found was at α=21° and side slip, β=10° for optimum pitching and yawing motion of cruise missile.

  19. Hydrodynamic Characteristics of an Aerodynamically Refined Planing-Tail Hull

    NASA Technical Reports Server (NTRS)

    McKann, Robert; Suydam, Henry B.

    1948-01-01

    The hydrodynamic characteristics of an aerodynamically refined planing-tail hull were determined from dynamic model tests in Langley tank no. 2. Stable take-off could be made for a wide range of locations of the center of gravity. The lower porpoising limit peak was high, but no upper limit was encountered. Resistance was high, being about the same as that of float seaplanes. A reasonable range of trims for stable landings was available only in the aft range of center-of-gravity locations.

  20. Aerodynamic Characterization of a Thin, High-Performance Airfoil for Use in Ground Fluids Testing

    NASA Technical Reports Server (NTRS)

    Broeren, Andy P.; Lee, Sam; Clark, Catherine

    2013-01-01

    The FAA has worked with Transport Canada and others to develop allowance times for aircraft operating in ice-pellet precipitation. Wind-tunnel testing has been carried out to better understand the flowoff characteristics and resulting aerodynamic effects of anti-icing fluids contaminated with ice pellets using a thin, high-performance wing section at the National Research Council of Canada Propulsion and Icing Wind Tunnel. The objective of this paper is to characterize the aerodynamic behavior of this wing section in order to better understand the adverse aerodynamic effects of anti-icing fluids and ice-pellet contamination. Aerodynamic performance data, boundary-layer surveys and flow visualization were conducted at a Reynolds number of approximately 6.0×10(exp 6) and a Mach number of 0.12. The clean, baseline model exhibited leading-edge stall characteristics including a leading-edge laminar separation bubble and minimal or no separation on the trailing edge of the main element or flap. These results were consistent with expected 2-D aerodynamics and showed no anomalies that could adversely affect the evaluation of anti-icing fluids and ice-pellet contamination on the wing. Tests conducted with roughness and leading-edge flow disturbances helped to explain the aerodynamic impact of the anti-icing fluids and contamination. The stalling characteristics of the wing section with fluid and contamination appear to be driven at least partially by the effects of a secondary wave of fluid that forms near the leading edge as the wing is rotated in the simulated takeoff profile. These results have provided a much more complete understanding of the adverse aerodynamic effects of anti-icing fluids and ice-pellet contamination on this wing section. This is important since these results are used, in part, to develop the ice-pellet allowance times that are applicable to many different airplanes.

  1. Aerodynamic Characterization of a Thin, High-Performance Airfoil for Use in Ground Fluids Testing

    NASA Technical Reports Server (NTRS)

    Broeren, Andy P.; Lee, Sam; Clark, Catherine

    2013-01-01

    The FAA has worked with Transport Canada and others to develop allowance times for aircraft operating in ice-pellet precipitation. Wind-tunnel testing has been carried out to better understand the flowoff characteristics and resulting aerodynamic effects of anti-icing fluids contaminated with ice pellets using a thin, high-performance wing section at the National Research Council of Canada Propulsion and Icing Wind Tunnel. The objective of this paper is to characterize the aerodynamic behavior of this wing section in order to better understand the adverse aerodynamic effects of anti-icing fluids and ice-pellet contamination. Aerodynamic performance data, boundary-layer surveys and flow visualization were conducted at a Reynolds number of approximately 6.0 x 10(exp 6) and a Mach number of 0.12. The clean, baseline model exhibited leading-edge stall characteristics including a leading-edge laminar separation bubble and minimal or no separation on the trailing edge of the main element or flap. These results were consistent with expected 2-D aerodynamics and showed no anomalies that could adversely affect the evaluation of anti-icing fluids and ice-pellet contamination on the wing. Tests conducted with roughness and leading-edge flow disturbances helped to explain the aerodynamic impact of the anti-icing fluids and contamination. The stalling characteristics of the wing section with fluid and contamination appear to be driven at least partially by the effects of a secondary wave of fluid that forms near the leading edge as the wing is rotated in the simulated takeoff profile. These results have provided a much more complete understanding of the adverse aerodynamic effects of anti-icing fluids and ice-pellet contamination on this wing section. This is important since these results are used, in part, to develop the ice-pellet allowance times that are applicable to many different airplanes.

  2. Aerodynamic and Performance Measurements on a SWT-2.3-101 Wind Turbine

    SciTech Connect

    Medina, P.; Singh, M.; Johansen, J.; Jove, A.R.; Machefaux, E.; Fingersh, L. J.; Schreck, S.

    2011-10-01

    This paper provides an overview of a detailed wind turbine field experiment being conducted at NREL under U.S. Department of Energy sponsorship. The purpose of the experiment is to obtain knowledge about the aerodynamics, performance, noise emission and structural characteristics of the Siemens SWT-2.3-101 wind turbine.

  3. Aerodynamic characteristics of the National Launch System (NLS) 1 1/2 stage launch vehicle

    NASA Technical Reports Server (NTRS)

    Springer, A. M.; Pokora, D. C.

    1994-01-01

    The National Aeronautics and Space Administration (NASA) is studying ways of assuring more reliable and cost effective means to space. One launch system studied was the NLS which included the l l/2 stage vehicle. This document encompasses the aerodynamic characteristics of the 1 l/2 stage vehicle. To support the detailed configuration definition two wind tunnel tests were conducted in the NASA Marshall Space Flight Center's 14x14-Inch Trisonic Wind Tunnel during 1992. The tests were a static stability and a pressure test, each utilizing 0.004 scale models. The static stability test resulted in the forces and moments acting on the vehicle. The aerodynamics for the reference configuration with and without feedlines and an evaluation of three proposed engine shroud configurations were also determined. The pressure test resulted in pressure distributions over the reference vehicle with and without feedlines including the reference engine shrouds. These pressure distributions were integrated and balanced to the static stability coefficients resulting in distributed aerodynamic loads on the vehicle. The wind tunnel tests covered a Mach range of 0.60 to 4.96. These ascent flight aerodynamic characteristics provide the basis for trajectory and performance analysis, loads determination, and guidance and control evaluation.

  4. Deep-Stall Aerodynamic Characteristics of T-Tail Aircraft

    NASA Technical Reports Server (NTRS)

    Taylor, Robert T.; Ray, Edward J.

    1965-01-01

    A wind-tunnel research program has been under-taken by the NASA to study the aerodynamic characteristics of T-tail aircraft at high angles of attack. The program was designed to show the effects on longitudinal stability and control of several configuration variables. The results to date do not allow the formulation of general design rules, but the effects of several configuration variables have been noted to have a prime influence on the post-stall characteristics. An increase in tail size, changes in the location of fuselage-mounted engine nacelles, and reduced fuselage-forebody lift were all found to have a beneficial effect on static longitudinal stability at high angles of attack.

  5. Longitudinal aerodynamic characteristics of an externally blown flap powered lift model with several propulsive system simulators

    NASA Technical Reports Server (NTRS)

    Hoad, D. R.

    1974-01-01

    An investigation of a four-engine externally blown flap (EBF) powered-lift transport was conducted in the Langley V/STOL tunnel to determine the effect of different engine configurations on the longitudinal aerodynamic characteristics. The different engine configurations were simulated by five different sets of propulsion simulators on a single aircraft model. Longitudinal aerodynamic data were obtained for each simulator on each flap deflection corresponding to cruise, take-off, and landing at a range of angles of attack and various thrust coefficients. The bypass ratio (BPR) 6.2 engine simulator provided the best lift and drag characteristics of the five simulators tested in the take-off and landing configurations. The poor performance of the BPR 10.0 and 3.2 engine simulators can be attributed to a mismatch of engine-model sizes or poor engine location and orientation. Isolated engine wake surveys indicated that a reasonable assessment of the aerodynamic characteristics of an engine-wing-flap configuration could be made if qualitative information were available which defined the engine wake characteristics. All configurations could be trimmed easily with relatively small horizontal-tail incidence angles; however, the take-off landing configurations required a high-lift tail.

  6. Plasma Aerodynamic Control Effectors for Improved Wind Turbine Performance

    SciTech Connect

    Mehul P. Patel; Srikanth Vasudevan; Robert C. Nelson; Thomas C. Corke

    2008-08-01

    Orbital Research Inc is developing an innovative Plasma Aerodynamic Control Effectors (PACE) technology for improved performance of wind turbines. The PACE system is aimed towards the design of "smart" rotor blades to enhance energy capture and reduce aerodynamic loading and noise using flow-control. The PACE system will provide ability to change aerodynamic loads and pitch distribution across the wind turbine blade without any moving surfaces. Additional benefits of the PACE system include reduced blade structure weight and complexity that should translate into a substantially reduced initial cost. During the Phase I program, the ORI-UND Team demonstrated (proof-of-concept) performance improvements on select rotor blade designs using PACE concepts. Control of both 2-D and 3-D flows were demonstrated. An analytical study was conducted to estimate control requirements for the PACE system to maintain control during wind gusts. Finally, independent laboratory experiments were conducted to identify promising dielectric materials for the plasma actuator, and to examine environmental effects (water and dust) on the plasma actuator operation. The proposed PACE system will be capable of capturing additional energy, and reducing aerodynamic loading and noise on wind turbines. Supplementary benefits from the PACE system include reduced blade structure weight and complexity that translates into reduced initial capital costs.

  7. X-31 aerodynamic characteristics determined from flight data

    NASA Technical Reports Server (NTRS)

    Kokolios, Alex

    1993-01-01

    The lateral aerodynamic characteristics of the X-31 were determined at angles of attack ranging from 20 to 45 deg. Estimates of the lateral stability and control parameters were obtained by applying two parameter estimation techniques, linear regression, and the extended Kalman filter to flight test data. An attempt to apply maximum likelihood to extract parameters from the flight data was also made but failed for the reasons presented. An overview of the System Identification process is given. The overview includes a listing of the more important properties of all three estimation techniques that were applied to the data. A comparison is given of results obtained from flight test data and wind tunnel data for four important lateral parameters. Finally, future research to be conducted in this area is discussed.

  8. An analytical procedure for evaluating shuttle abort staging aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Meyer, R.

    1973-01-01

    An engineering analysis and computer code (AERSEP) for predicting Space Shuttle Orbiter - HO Tank longitudinal aerodynamic characteristics during abort separation has been developed. Computed results are applicable at Mach numbers above 2 for angle-of-attack between plus or minus 10 degrees. No practical restrictions on orbiter-tank relative positioning are indicated for tank-under-orbiter configurations. Input data requirements and computer running times are minimal facilitating program use for parametric studies, test planning, and trajectory analysis. In a majority of cases AERSEP Orbiter-Tank interference predictions are as accurate as state-of-the-art estimates for interference-free or isolated-vehicle configurations. AERSEP isolated-orbiter predictions also show excellent correlation with data.

  9. Aerodynamic characteristics of proposed assured crew return capability (ACRC) configurations

    NASA Astrophysics Data System (ADS)

    Ware, George M.; Spencer, Bernard, Jr.; Micol, John R.

    1989-07-01

    The aerodynamic characteristics of seven reentry configurations suggested as possible candidate vehicles to return crew members from the U.S. Space Station Freedom to earth has been reviewed. The shapes varied from those capable of purely ballistic entry to those capable of gliding entry and fromk parachute landing to conventional landing. Data were obtained from existing (published and unpublished) sources and from recent wind tunnel tests. The lifting concepts are more versatile and satisfy all the mission requirements. Two of the lifting shapes studied appear promising - a lifting body and a deployable wing concept. The choice of an ACRC concept, however, will be made after all factors involving transportation from earth to orbit and back to earth again have been weighed.

  10. Advanced Noise Control Fan Aerodynamic Performance

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F., Jr.

    2009-01-01

    The Advanced Noise Control Fan at the NASA Glenn Research Center is used to experimentally analyze fan generated acoustics. In order to determine how a proposed noise reduction concept affects fan performance, flow measurements can be used to compute mass flow. Since tedious flow mapping is required to obtain an accurate mass flow, an equation was developed to correlate the mass flow to inlet lip wall static pressure measurements. Once this correlation is obtained, the mass flow for future configurations can be obtained from the nonintrusive wall static pressures. Once the mass flow is known, the thrust and fan performance can be evaluated. This correlation enables fan acoustics and performance to be obtained simultaneously without disturbing the flow.

  11. Numerical Study of Aerodynamic Characteristics of a Symmetric NACA Section with Simulated Ice Shapes

    NASA Astrophysics Data System (ADS)

    Tabatabaei, N.; Cervantes, M. J.; Trivedi, C.; Aidanpää, Jan-Olof

    2016-09-01

    To develop a numerical model of icing on wind turbine blades, a CFD simulation was conducted to investigate the effect of critical ice accretions on the aerodynamic characteristics of a 0.610 m chord NACA 0011 airfoil section. Aerodynamic performance coefficients and pressure profile were calculated and compared with the available measurements for a chord Reynolds number of 1.83x106. Ice shapes were simulated with flat plates (spoiler-ice) extending along the span of the wing. Lift, drag, and pressure coefficients were calculated in zero angle of attack through the steady state and transient simulations. Different approaches of numerical studies have been applied to investigate the icing conditions on the blades. The simulated separated flow over the sharp spoilers is challenging and can be seen as a worst test case for validation. It allows determining a reliable strategy to simulate real ice shapes [1] for which the detailed validation cannot easily be provided.

  12. Aerodynamic performance of an annular classical airfoil cascade

    NASA Technical Reports Server (NTRS)

    Bergsten, D. E.; Stauter, R. C.; Fleeter, S.

    1983-01-01

    Results are presented for a series of experiments that were performed in a large-scale subsonic annular cascade facility that was specifically designed to provide three-dimensional aerodynamic data for the verification of numerical-calculation codes. In particular, the detailed three-dimensional aerodynamic performance of a classical flat-plate airfoil cascade is determined for angles of incidence of 0, 5, and 10 deg. The resulting data are analyzed and are correlated with predictions obtained from NASA's MERIDL and TSONIC numerical programs. It is found that: (1) at 0 and 5 deg, the airfoil surface data show a good correlation with the predictions; (2) at 10 deg, the data are in fair agreement with the numerical predictions; and (3) the two-dimensional Gaussian similarity relationship is appropriate for the wake velocity profiles in the mid-span region of the airfoil.

  13. Computational modeling of aerodynamic characteristics in sprayed and spiraled precalciner

    NASA Astrophysics Data System (ADS)

    Li, Xiangguo; Ma, Baoguo; Hu, Zhenwu

    2008-08-01

    Based on the structural and work characteristics of a spiraled and sprayed precalciner, the RNG k- ɛ model and the SIMPLE method were used to simulate the aerodynamic characteristics in a sprayed and spiraled precalciner. The simulation results demonstrate that the flow area of airflow was increased abruptly due to the reduced part of the bottom of precalciners, which attributed to a sprayed effect. With the mix of the tertiary air with the swirl flow and secondary air, a high-speed zone was formed in the opposite side of the inlet of tertiary air, in which the highest speed was 32.97 m/s. Moreover, the inlet of raw meal designed in the high-speed zone can be propitious to the decentralization of the raw meal. A back-flow zone was formed near the side of the inlet of tertiary air, in which the velocity was negative. From the analysis of the results, the flow field of the precalciner is composed of a sprayed zone, a high-speed zone, a back-flow zone and cylinder zone; moreover, the simulation results agree with those of the engineering compared to the in situ results. The results also showed that the CFD method can be used to give the basis for optimizing the geometrical design and flow parameters of a precalciner.

  14. Mathematical modeling of the aerodynamic characteristics in flight dynamics

    NASA Technical Reports Server (NTRS)

    Tobak, M.; Chapman, G. T.; Schiff, L. B.

    1984-01-01

    Basic concepts involved in the mathematical modeling of the aerodynamic response of an aircraft to arbitrary maneuvers are reviewed. The original formulation of an aerodynamic response in terms of nonlinear functionals is shown to be compatible with a derivation based on the use of nonlinear functional expansions. Extensions of the analysis through its natural connection with ideas from bifurcation theory are indicated.

  15. Modeling of aircraft unsteady aerodynamic characteristics. Part 1: Postulated models

    NASA Technical Reports Server (NTRS)

    Klein, Vladislav; Noderer, Keith D.

    1994-01-01

    A short theoretical study of aircraft aerodynamic model equations with unsteady effects is presented. The aerodynamic forces and moments are expressed in terms of indicial functions or internal state variables. The first representation leads to aircraft integro-differential equations of motion; the second preserves the state-space form of the model equations. The formulations of unsteady aerodynamics is applied in two examples. The first example deals with a one-degree-of-freedom harmonic motion about one of the aircraft body axes. In the second example, the equations for longitudinal short-period motion are developed. In these examples, only linear aerodynamic terms are considered. The indicial functions are postulated as simple exponentials and the internal state variables are governed by linear, time-invariant, first-order differential equations. It is shown that both approaches to the modeling of unsteady aerodynamics lead to identical models.

  16. Wind-tunnel investigation of aerodynamic performance, steady amd vibratory loads, surface temperatures, and acoustic characteristics of a large-scale twin-engine upper-surface blown jet-flap configuration

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Static and wind-on tests were conducted to determine the aerodynamic characteristics of and the effects of jet impingement on the wing of a large scale upper surface blown configuration powered with an actual turbine engine. The wing and flaps were instrumented with experimental dual-sensing transducer units consisting of a fluctuating pressure gage, a vibratory accelerometer, and a surface mounted alumel thermocouple. Noise directivity and spectral content measurements were obtained for various flap configurations and various engine thrust settings to provide baseline noise data for other upper surface blown configurations.

  17. Wing Flexion and Aerodynamics Performance of Insect Free Flights

    NASA Astrophysics Data System (ADS)

    Dong, Haibo; Liang, Zongxian; Ren, Yan

    2010-11-01

    Wing flexion in flapping flight is a hallmark of insect flight. It is widely thought that wing flexibility and wing deformation would potentially provide new aerodynamic mechanisms of aerodynamic force productions over completely rigid wings. However, there are lack of literatures on studying fluid dynamics of freely flying insects due to the presence of complex shaped moving boundaries in the flow domain. In this work, a computational study of freely flying insects is being conducted. High resolution, high speed videos of freely flying dragonflies and damselflies is obtained and used as a basis for developing high fidelity geometrical models of the dragonfly body and wings. 3D surface reconstruction technologies are used to obtain wing topologies and kinematics. The wing motions are highly complex and a number of different strategies including singular vector decomposition of the wing kinematics are used to examine the various kinematical features and their impact on the wing performance. Simulations are carried out to examine the aerodynamic performance of all four wings and understand the wake structures of such wings.

  18. Aerodynamic characteristics of wheelchairs. [Langley V/STOL wind tunnel tests for human factors engineering

    NASA Technical Reports Server (NTRS)

    Coe, P. L., Jr.

    1979-01-01

    The overall aerodynamic drag characteristics of a conventional wheelchair were defined and the individual drag contributions of its components were determined. The results show that a fiftieth percentile man sitting in the complete wheelchair would experience an aerodynamic drag coefficient on the order of 1.4.

  19. Experimental study on the aerodynamic performance of a Savonius rotor

    SciTech Connect

    Fujisawa, Nobuyuki; Gotoh, Futoshi . Dept. of Mechanical Engineering)

    1994-08-01

    The aerodynamic performance of a Savonius rotor has been studied by measuring the pressure distributions on the blade surfaces at various rotor angles and tip-speed ratios. It is found that the pressure distributions on the rotating rotor differ remarkably from those on the still rotor especially on the convex side of the advancing blade, where a low pressure region is formed by the moving wall effect of the blade. The torque and power performances, evaluated by integrating the pressure, are in close agreement with those by the direct torque measurement. The drag and side force performance is also studied.

  20. Ontogeny of aerodynamics in mallards: comparative performance and developmental implications.

    PubMed

    Dial, Terry R; Heers, Ashley M; Tobalske, Bret W

    2012-11-01

    Wing morphology correlates with flight performance and ecology among adult birds, yet the impact of wing development on aerodynamic capacity is not well understood. Recent work using chukar partridge (Alectoris chukar), a precocial flier, indicates that peak coefficients of lift and drag (C(L) and C(D)) and lift-to-drag ratio (C(L):C(D)) increase throughout ontogeny and that these patterns correspond with changes in feather microstructure. To begin to place these results in a comparative context that includes variation in life-history strategy, we used a propeller and force-plate model to study aerodynamic force production across a developmental series of the altricial-flying mallard (Anas platyrhynchos). We observed the same trend in mallards as reported for chukar in that coefficients of vertical (C(V)) and horizontal force (C(H)) and C(V):C(H) ratio increased with age, and that measures of gross-wing morphology (aspect ratio, camber and porosity) in mallards did not account for intraspecific trends in force production. Rather, feather microstructure (feather unfurling, rachis width, feather asymmetry and barbule overlap) all were positively correlated with peak C(V):C(H). Throughout ontogeny, mallard primary feathers became stiffer and less transmissive to air at both macroscale (between individual feathers) and microscale (between barbs/barbules/barbicels) levels. Differences between species were manifest primarily as heterochrony of aerodynamic force development. Chukar wings generated measurable aerodynamic forces early (<8 days), and improved gradually throughout a 100 day ontogenetic period. Mallard wings exhibited delayed aerodynamic force production until just prior to fledging (day 60), and showed dramatic improvement within a condensed 2-week period. These differences in timing may be related to mechanisms of escape used by juveniles, with mallards swimming to safety and chukar flap-running up slopes to take refuge. Future comparative work should test

  1. Aerodynamic Characteristics of Caliber .22 Long Rifle Match Ammunition

    DTIC Science & Technology

    1990-11-01

    range. The Aerodynamic-s Range is an enclosed, cimate -controlled range, instrumented with spark-photography stations to record the motion of the...slant of groups in the wind from a right-hand twist of rifling is due to aerodynamic jump, which is an effective change in the vertical angle of...Director, USAHEL ATTN: SLCHE-IS, Mr. B. Corona Mr. P. Ellis Mr. J. Torre 64 USER EVALUArION SHEET/ CHANGE OF ADDRIESS9 This Uboray underk a c-effor- to imo t

  2. Characteristics of Pressure Sensitive Paint Intrusiveness Effects on Aerodynamic Data

    NASA Technical Reports Server (NTRS)

    Amer, Tahani R.; Liu, Tianshu; Oglesby, Donald M.

    2001-01-01

    One effect of using pressure sensitive paint (PSP) is the potential intrusiveness to the aerodynamic characteristics of the model. The paint thickness and roughness may affect the pressure distribution, and therefore, the forces and moments on the wind tunnel model. A study of these potential intrusive effects was carried out at NASA Langley Research Center where a series of wind tunnel tests were conducted using the Modem Design of Experiments (MDOE) test approach. The PSP effects on the integrated forces were measured on two different models at different test conditions in both the Low Turbulence Pressure Tunnel (LTPT) and the Unitary Plan Wind Tunnel (UPWT) at Langley. The paint effect was found to be very small over a range of Reynolds numbers, Mach numbers and angles of attack. This is due to the very low surface roughness of the painted surface. The surface roughness, after applying the NASA Langley developed PSP, was lower than that of the clean wing. However, the PSP coating had a localized effects on the pressure taps, which leads to an appreciable decrease in the pressure tap reading.

  3. Acoustic and aerodynamic characteristics of ejectives in Amharic

    NASA Astrophysics Data System (ADS)

    Demolin, Didier

    2004-05-01

    This paper invetsigates the main phonetic characteristics that distinguishes ejectives from pulmonic sounds in Amharic. In this language, there are five ejectives that can be phonemically singleton or geminate. Duration measurements have been made in intervocalic position for pulmonic stops and for each type of ejective, taking into account the overall duration and VOT. Results show that ejective stops have a higher amplitude burst than pulmonic stops. The duration of the noise is shorter for ejective fricatives compared to pulmonic fricatives. At the end of ejective fricatives, there is a 30-ms glottal lag that is not present in pulmonic fricatives. Geminate ejectives are realized by delaying the elevation of the larynx. This can be observed on the spectrographic data by an increase of the noise at the end of the geminate ejectives. Aerodynamic data have been collected in synchronization with the acoustic recordings. The main observations are that pharyngeal pressures values are much higher than what is usually assumed (up to 40 CmH2O for velars) and that the delayed command in the elevation of the larynx of geminate ejectives is shown by two phases in the rise of pharyngeal pressure.

  4. Supersonic aerodynamic characteristics of an advanced F-16 derivative aircraft configuration

    NASA Technical Reports Server (NTRS)

    Fox, Mike C.; Forrest, Dana K.

    1993-01-01

    A supersonic wind tunnel investigation was conducted in the NASA Langley Unitary Plan Wind Tunnel on an advanced derivative configuration of the United States Air Force F-16 fighter. Longitudinal and lateral directional force and moment data were obtained at Mach numbers of 1.60 to 2.16 to evaluate basic performance parameters and control effectiveness. The aerodynamic characteristics for the F-16 derivative model were compared with the data obtained for the F-16C model and also with a previously tested generic wing model that features an identical plan form shape and similar twist distribution.

  5. Measured and Computed Hypersonic Aerodynamic/Aeroheating Characteristics for an Elliptically Blunted Flared Cylinder

    NASA Technical Reports Server (NTRS)

    Greene, Francis A.; Buck, Gregory M.; Wood, William A.

    2001-01-01

    Computational and experimental hypersonic aerodynamic forces and moments and aeroheating levels for Kistler Aerospace Corporation's baseline orbiter vehicle at incidence are presented. Experimental data were measured in ground-based facilities at the Langley Research Center and predictions were performed using the Langley Aerothermodynamic Upwind Relaxation Algorithm code. The test parameters were incidence (-4 to 24 degrees), freestream Mach number (6 to 10), freestream ratio of specific heats (1.2 to 1.4), and freestream Reynolds number (0.5 to 8.0 million per foot). The effects of these parameters on aerodynamic characteristics, as well as the effects of Reynolds number on measured heating levels are discussed. Good agreement between computational and experimental aerodynamic and aeroheating values were observed over the wide range of test parameters examined. Reynolds number and ratio of specific heats were observed to significantly alter the trim L/D value. At Mach 6, laminar flow, was observed along the entire windward centerline up to the flare for all angles and Reynolds numbers tested. Flow over the flare transitioned front laminar to transitional turbulent between 4 and 8 million per foot at 8 and 12 degrees angle of attack, and near 4 million per foot at 16 degrees angle of attack.

  6. Measured and Computed Hypersonic Aerodynamic/Aeroheating Characteristics for an Elliptically Blunted Flared Cylinder

    NASA Technical Reports Server (NTRS)

    Greene, Francis A.; Buck, Gregory M.; Wood, William A.

    2001-01-01

    Computational and experimental hypersonic aerodynamic forces and moments and aeroheating levels for Kistler Aerospace Corporation's baseline orbiter vehicle at incidence are presented. Experimental data were measured in ground-based facilities at the Langley Research Center and predictions were performed using the Langley Aerothermodynamic Upwind Relaxation Algorithm code. The test parameters were incidence (-4 to 24 degrees), freestream Mach number (6 to 10),freestream ratio o specific heats (1.2 to 1.4), and freestream Reynolds number (0.5 to 8.0 million per foot). The effects of these parameters on aerodynamic characteristics, as well as the effects of Reynolds number on measured heating levels are discussed. Good agreement between computational and experimental aerodynamic and aeroheating values were observed over the wide range of test parameters examined. Reynolds number and ratio of specific heats were observed to significantly alter the trim L/D value. At Mach 6, laminar flow was observed along the entire windward centerline tip to the flare for all angles and Reynolds numbers tested. Flow over the flare transitioned from laminar to transitional/turbulent between 4 and 8 million per foot at 8 and 12 degrees angle of attack, and near 4 million per foot at 16 degrees angle of attack.

  7. High performance parallelized implicit Euler solver for the analysis of unsteady aerodynamic flows

    NASA Astrophysics Data System (ADS)

    Borel, C.; Bredif, M.

    Simulation of transient flows is more and more useful for industrial applications in aeronautics. For instance, the unsteady aerodynamic coefficients can be of great importance in order to predict the behavior of flying bodies: this is in particular the case for missiles which are spun around their longitudinal axis. It is also well known that the experimental tools used to evaluate the unsteady aerodynamic characteristics present a certain number of limitations: complexity of the experiments, limited degree of accuracy, high costs and delays. In this context, the Computational Aerodynamics Department of Matra Defense has been developing a software library called AEROLOG for the prediction of the steady and unsteady aerodynamics of tactical missiles using Computational Fluid Dynamics (CFD) techniques. The aim of this paper is as follows: (1) Detailed presentation of the numerical method, with particular emphasis on the high performances in terms of computational time achieved thanks to the use of an implicit scheme combined with a domain decomposition of structured mesh well suited for vector and parallel implementation, and (2) Analysis of 2-D and 3-D unsteady numerical simulations corresponding to academic and industrial cases, showing the accuracy of the method together with its range of applications.

  8. An Experimental Study on the aerodynamic and aeroacoustic performances of Maple-Seed-Inspired UAV Propellers

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Ning, Zhe

    2016-11-01

    Due to the auto-rotating trait of maple seeds during falling down process, flow characteristics of rotating maple seeds have been studied by many researchers in recent years. In the present study, an experimental investigation was performed to explore maple-seed-inspired UAV propellers for improved aerodynamic and aeroacoustic performances. Inspired by the auto-rotating trait of maple seeds, the shape of a maple seed is leveraged for the planform design of UAV propellers. The aerodynamic and aeroacoustic performances of the maple-seed-inspired propellers are examined in great details, in comparison with a commercially available UAV propeller purchased on the market (i.e., a baseline propeller). During the experiments, in addition to measuring the aerodynamic forces generated by the maple-seed-inspired propellers and the baseline propeller, a high-resolution Particle Image Velocimetry (PIV) system was used to quantify the unsteady flow structures in the wakes of the propellers. The aeroacoustic characteristics of the propellers are also evaluated by leveraging an anechoic chamber available at the Aerospace Engineering Department of Iowa State University. The research work is supported by National Science Foundation under Award Numbers of OSIE-1064235.

  9. Effects of wing flexibility on aerodynamic performance in hovering flight

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Wei, Mingjun

    2012-11-01

    In this study, we use a strong-coupling approach to simulate three dimensional flexible flapping wings in hovering flight. The approach is based on a uniform description of both fluid and solid in global Eulerian framework. There has been extensive validation of the current approach with other numerical simulation and experiments. Then we apply our approach to simulate flapping wings with different flexibility and other control parameters. The simulation results allow us to study directly the effects of wing flexibility on the aerodynamic performance of hovering flight. Supported by ARL.

  10. Aerodynamic characteristics and respiratory deposition of fungal fragments

    NASA Astrophysics Data System (ADS)

    Cho, Seung-Hyun; Seo, Sung-Chul; Schmechel, Detlef; Grinshpun, Sergey A.; Reponen, Tiina

    The purpose of this study was to investigate the aerodynamic characteristics of fungal fragments and to estimate their respiratory deposition. Fragments and spores of three different fungal species ( Aspergillus versicolor, Penicillium melinii, and Stachybotrys chartarum) were aerosolized by the fungal spore source strength tester (FSSST). An electrical low-pressure impactor (ELPI) measured the size distribution in real-time and collected the aerosolized fungal particles simultaneously onto 12 impactor stages in the size range of 0.3-10 μm utilizing water-soluble ZEF-X10 coating of the impaction stages to prevent spore bounce. For S. chartarum, the average concentration of released fungal fragments was 380 particles cm -3, which was about 514 times higher than that of spores. A. versicolor was found to release comparable amount of spores and fragments. Microscopic analysis confirmed that S. chartarum and A. versicolor did not show any significant spore bounce, whereas the size distribution of P. melinii fragments was masked by spore bounce. Respiratory deposition was calculated using a computer-based model, LUDEP 2.07, for an adult male and a 3-month-old infant utilizing the database on the concentration and size distribution of S. chartarum and A. versicolor aerosols measured by the ELPI. Total deposition fractions for fragments and spores were 27-46% and 84-95%, respectively, showing slightly higher values in an infant than in an adult. For S. chartarum, fragments demonstrated 230-250 fold higher respiratory deposition than spores, while the number of deposited fragments and spores of A. versicolor were comparable. It was revealed that the deposition ratio (the number of deposited fragments divided by that of deposited spores) in the lower airways for an infant was 4-5 times higher than that for an adult. As fungal fragments have been shown to contain mycotoxins and antigens, further exposure assessment should include the measurement of fungal fragments for

  11. Forward flight of birds revisited. Part 1: aerodynamics and performance.

    PubMed

    Iosilevskii, G

    2014-10-01

    This paper is the first part of the two-part exposition, addressing performance and dynamic stability of birds. The aerodynamic model underlying the entire study is presented in this part. It exploits the simplicity of the lifting line approximation to furnish the forces and moments acting on a single wing in closed analytical forms. The accuracy of the model is corroborated by comparison with numerical simulations based on the vortex lattice method. Performance is studied both in tethered (as on a sting in a wind tunnel) and in free flights. Wing twist is identified as the main parameter affecting the flight performance-at high speeds, it improves efficiency, the rate of climb and the maximal level speed; at low speeds, it allows flying slower. It is demonstrated that, under most circumstances, the difference in performance between tethered and free flights is small.

  12. On-orbit free molecular flow aerodynamic characteristics of a proposal space operations center configuration

    NASA Technical Reports Server (NTRS)

    Romere, P. O.

    1982-01-01

    A proposed configuration for a Space Operations Center is presented in its eight stages of buildup. The on orbit aerodynamic force and moment characteristics were calculated for each stage based upon free molecular flow theory. Calculation of the aerodynamic characteristics was accomplished through the use of an orbital aerodynamic computer program, and the computation method is described with respect to the free molecular theory used. The aerodynamic characteristics are presented in tabulated form for each buildup stage at angles of attack from 0 to 360 degrees and roll angles from -60 to +60 degrees. The reference altitude is 490 kilometers, however, the data should be applicable for altitudes below 490 kilometers down to approximately 185 kilometers.

  13. Numerical and experimental study on aerodynamic performance of small axial flow fan with splitter blades

    NASA Astrophysics Data System (ADS)

    Zhu, Lifu; Jin, Yingzi; Li, Yi; Jin, Yuzhen; Wang, Yanping; Zhang, Li

    2013-08-01

    To improve the aerodynamic performance of small axial flow fan, in this paper the design of a small axial flow fan with splitter blades is studied. The RNG k-ɛ turbulence model and SIMPLE algorithm were applied to the steady simulation calculation of the flow field, and its result was used as the initial field of the large eddy simulation to calculate the unsteady pressure field. The FW-H noise model was adopted to predict aerodynamic noise in the six monitoring points. Fast Fourier transform algorithm was applied to process the pressure signal. Experiment of noise testing was done to further investigate the aerodynamic noise of fans. And then the results obtained from the numerical simulation and experiment were described and analyzed. The results show that the static characteristics of small axial fan with splitter blades are similar with the prototype fan, and the static characteristics are improved within a certain range of flux. The power spectral density at the six monitoring points of small axial flow fan with splitter blades have decreased to some extent. The experimental results show sound pressure level of new fan has reduced in most frequency bands by comparing with prototype fan. The research results will provide a proof for parameter optimization and noise prediction of small axial flow fans with high performance.

  14. An aerodynamic performance analysis of a perforated wind turbine blade

    NASA Astrophysics Data System (ADS)

    Didane, D. H.; Mohd, S.; Subari, Z.; Rosly, N.; Ghafir, M. F. Abdul; Mohd Masrom, M. F.

    2016-11-01

    Wind power is one of the important renewable energy sources. Currently, many researches are focusing on improving the aerodynamic performance of wind turbine blades through simulations and wind tunnel testing. In the present study, the aerodynamic performance of the perforated Eqwin blade (shell type blade) is investigated by using numerical simulation. Three types of slots namely circular, horizontal rectangular and vertical rectangular were evaluated. It was found that the optimum angle of attack for a perforated shell type blade was 12° with maximum Cl/Cd value of 6.420. In general, for all the perforated blade cases, Cl/Cd tended to decrease as the slot size increased except for the circular slot with 5 mm diameter. This was due to the disturbance of the airflow in lower side region which passed through the bigger slot size. Among the modified slots; the circular slot with diameter of 5 mm would be the best slot configuration that can be considered for blade fabrication. The Cl/Cd obtained was 6.46 which is about 5% more than the value of the reference blade. Moreover, the introduced slot would also reduce the overall weight of the blade by 1.3%.

  15. 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 2; High Lift

    NASA Technical Reports Server (NTRS)

    Baize, Daniel G. (Editor)

    1999-01-01

    The High-Speed Research Program and NASA Langley Research Center sponsored the NASA High-Speed Research Program Aerodynamic Performance Workshop on February 25-28, 1997. The workshop was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of Configuration Aerodynamics (transonic and supersonic cruise drag, prediction and minimization), High-Lift, Flight Controls, Supersonic Laminar Flow Control, and Sonic Boom Prediction. The workshop objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientist and engineers working HSCT aerodynamics. In particular, single- and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT Motion Simulator results were presented along with executives summaries for all the Aerodynamic Performance technology areas.

  16. Forward flight of birds revisited. Part 1: aerodynamics and performance

    PubMed Central

    Iosilevskii, G.

    2014-01-01

    This paper is the first part of the two-part exposition, addressing performance and dynamic stability of birds. The aerodynamic model underlying the entire study is presented in this part. It exploits the simplicity of the lifting line approximation to furnish the forces and moments acting on a single wing in closed analytical forms. The accuracy of the model is corroborated by comparison with numerical simulations based on the vortex lattice method. Performance is studied both in tethered (as on a sting in a wind tunnel) and in free flights. Wing twist is identified as the main parameter affecting the flight performance—at high speeds, it improves efficiency, the rate of climb and the maximal level speed; at low speeds, it allows flying slower. It is demonstrated that, under most circumstances, the difference in performance between tethered and free flights is small. PMID:26064548

  17. Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach.

    PubMed

    Nakata, Toshiyuki; Liu, Hao

    2012-02-22

    Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements.

  18. Aerodynamic and directional acoustic performance of a scoop inlet

    NASA Technical Reports Server (NTRS)

    Abbott, J. M.; Dietrich, D. A.

    1977-01-01

    Aerodynamic and directional acoustic performances of a scoop inlet were studied. The scoop inlet is designed with a portion of the lower cowling extended forward to direct upward any noise that is propagating out the front of the engine toward the ground. The tests were conducted in an anechoic wind tunnel facility at free stream velocities of 0, 18, 41, and 61 m/sec and angles of attack from -10 deg to 120 deg. Inlet throat Mach number was varied from 0.30 to 0.75. Aerodynamically, at a free stream velocity of 41 m/sec, the design throat Mach number (0.63), and an angle of attack of 50 deg, the scoop inlet total pressure recovery was 0.989 and the total pressure distortion was 0.15. The angles of attack where flow separation occurred with the scoop inlet were higher than those for a conventional symmetric inlet. Acoustically, the scoop inlet provided a maximum noise reduction of 12 to 15 db below the inlet over the entire range of throat Mach number and angle of attack at a free-stream velocity of 41 m/sec.

  19. A numerical investigation into the aerodynamic characteristics and aeroelastic stability of a footbridge

    NASA Astrophysics Data System (ADS)

    Taylor, I. J.; Vezza, M.

    2009-01-01

    The results of a numerical investigation into the aerodynamic characteristics and aeroelastic stability of a proposed footbridge across a highway in the north of England are presented. The longer than usual span, along with the unusual nature of the pedestrian barriers, indicated that the deck configuration was likely to be beyond the reliable limits of the British design code BD 49/01. The calculations were performed using the discrete vortex method, DIVEX, developed at the Universities of Glasgow and Strathclyde. DIVEX has been successfully validated on a wide range of problems, including the aeroelastic response of bridge deck sections. In particular, the investigation focussed on the effects of non-standard pedestrian barriers on the structural integrity of the bridge. The proposed deck configuration incorporated a barrier comprised of angled flat plates, and the bridge was found to be unstable at low wind speeds, with the plates having a strong turning effect on the flow at the leading edge of the deck. These effects are highlighted in both a static and dynamic analysis of the bridge deck, along with modifications to the design that aim to improve the aeroelastic stability of the deck. Proper orthogonal decomposition (POD) was also used to investigate the unsteady pressure field on the upper surface of the static bridge deck. The results of the flutter investigation and the POD analysis highlight the strong influence of the pedestrian barriers on the overall aerodynamic characteristics and aeroelastic stability of the bridge.

  20. Aeroacoustics and aerodynamic performance of a rotor with flatback airfoils.

    SciTech Connect

    Paquette, Joshua A.; Barone, Matthew Franklin; Christiansen, Monica; Simley, Eric

    2010-06-01

    The aerodynamic performance and aeroacoustic noise sources of a rotor employing flatback airfoils have been studied in field test campaign and companion modeling effort. The field test measurements of a sub-scale rotor employing nine meter blades include both performance measurements and acoustic measurements. The acoustic measurements are obtained using a 45 microphone beamforming array, enabling identification of both noise source amplitude and position. Semi-empirical models of flatback airfoil blunt trailing edge noise are developed and calibrated using available aeroacoustic wind tunnel test data. The model results and measurements indicate that flatback airfoil noise is less than drive train noise for the current test turbine. It is also demonstrated that the commonly used Brooks, Pope, and Marcolini model for blunt trailing edge noise may be over-conservative in predicting flatback airfoil noise for wind turbine applications.

  1. Transonic aerodynamic characteristics of a proposed wing-body reusable launch vehicle concept

    NASA Technical Reports Server (NTRS)

    Springer, A. M.

    1995-01-01

    A proposed wing-body reusable launch vehicle was tested in the NASA Marshall Space Flight Center's 14 x 14-inch trisonic wind tunnel during the winter of 1994. This test resulted in the vehicle's subsonic and transonic, Mach 0.3 to 1.96, longitudinal and lateral aerodynamic characteristics. The effects of control surface deflections on the basic vehicle's aerodynamics, including a body flap, elevons, ailerons, and tip fins, are presented.

  2. Transonic Aerodynamic Characteristics of a Proposed Wing Body Reusable Launch Vehicle Concept

    NASA Technical Reports Server (NTRS)

    Springer, Anthony M.

    1996-01-01

    A proposed wing body reusable launch vehicle was tested in the Marshall Space Flight Center (MSFC) 14 x 14 inch trisonic wind tunnel during the winter of 1994. this test resulted in the vehicle's subsonic and transonic (Mach 03 to 1.96) longitudinal and lateral aerodynamic characteristics. The effects of control surface deflections on the basic vehicle aerodynamics including a body flap, elevons, ailerons, and tip fins are presented.

  3. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    SciTech Connect

    Fleeter, S.; Lawless, P.B.

    1995-10-01

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

  4. Aerodynamic characteristics of NACA 4412 airfoil sction with flap

    NASA Astrophysics Data System (ADS)

    Ockfen, Alex E.; Matveev, Konstantin I.

    2009-09-01

    Wing-in-Ground vehicles and aerodynamically assisted boats take advantage of increased lift and reduced drag of wing sections in the ground proximity. At relatively low speeds or heavy payloads of these craft, a flap at the wing trailing-ground-effect flow id numerically investigated in this study. The computational method consists of a steady-state, incompressible, finite volume method utilizing the Spalart-Allmaras turbulence model. Grid generation and solution of the Navier-Stokes equations are completed flow with a flap, as well as ground-effect motion without a flap. Aerodynamic forces are plain flap. Changes in the flow introduced with the flap addition are also discussed. Overall, the use of a flap on wings with small attack angles is found to be beneficial for small flap deflections up to 5% of the chord, where the contribution of lift augmentation exceeds the drag increase, yielding an augmented lift-to-drag ratio

  5. Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels (Glaucomys sabrinus).

    PubMed

    Bahlman, Joseph W; Swartz, Sharon M; Riskin, Daniel K; Breuer, Kenneth S

    2013-03-06

    Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60-125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels (Glaucomys sabrinus) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight.

  6. Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels (Glaucomys sabrinus)

    PubMed Central

    Bahlman, Joseph W.; Swartz, Sharon M.; Riskin, Daniel K.; Breuer, Kenneth S.

    2013-01-01

    Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60–125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels (Glaucomys sabrinus) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight. PMID:23256188

  7. Investigations on the Aerodynamic Characteristics and Blade Excitations of the Radial Turbine with Pulsating Inlet Flow

    NASA Astrophysics Data System (ADS)

    Liu, Yixiong; Yang, Ce; Yang, Dengfeng; Zhang, Rui

    2016-04-01

    The aerodynamic performance, detailed unsteady flow and time-based excitations acting on blade surfaces of a radial flow turbine have been investigated with pulsation flow condition. The results show that the turbine instantaneous performance under pulsation flow condition deviates from the quasi-steady value significantly and forms obvious hysteretic loops around the quasi-steady conditions. The detailed analysis of unsteady flow shows that the characteristic of pulsation flow field in radial turbine is highly influenced by the pulsation inlet condition. The blade torque, power and loading fluctuate with the inlet pulsation wave in a pulse period. For the blade excitations, the maximum and the minimum blade excitations conform to the wave crest and wave trough of the inlet pulsation, respectively, in time-based scale. And toward blade chord direction, the maximum loading distributes along the blade leading edge until 20% chord position and decreases from the leading to trailing edge.

  8. Aerodynamic characteristics of sixteen electric, hybrid, and subcompact vehicles

    NASA Technical Reports Server (NTRS)

    Kurtz, D. W.

    1979-01-01

    An elementary electric and hybrid vehicle aerodynamic data base was developed using data obtained on sixteen electric, hybrid, and sub-compact production vehicles tested in the Lockheed-Georgia low-speed wind tunnel. Zero-yaw drag coefficients ranged from a high of 0.58 for a boxey delivery van and an open roadster to a low of about 0.34 for a current four-passenger proto-type automobile which was designed with aerodynamics as an integrated parameter. Vehicles were tested at yaw angles up to 40 degrees and a wing weighting analysis is presented which yields a vehicle's effective drag coefficient as a function of wing velocity and driving cycle. Other parameters investigated included the effects of windows open and closed, radiators open and sealed, and pop-up headlights. Complete six-component force and moment data are presented in both tabular and graphical formats. Only limited commentary is offered since, by its very nature, a data base should consist of unrefined reference material. A justification for pursuing efficient aerodynamic design of EHVs is presented.

  9. Steady-state and transitional aerodynamic characteristics of a wing in simulated heavy rain

    NASA Technical Reports Server (NTRS)

    Campbell, Bryan A.; Bezos, Gaudy M.

    1989-01-01

    The steady-state and transient effects of simulated heavy rain on the subsonic aerodynamic characteristics of a wing model were determined in the Langley 14- by 22-Foot Subsonic Tunnel. The 1.29 foot chord wing was comprised of a NACA 23015 airfoil and had an aspect ratio of 6.10. Data were obtained while test variables of liquid water content, angle of attack, and trailing edge flap angle were parametrically varied at dynamic pressures of 10, 30, and 50 psf (i.e., Reynolds numbers of .76x10(6), 1.31x10(6), and 1.69x10(6)). The experimental results showed reductions in lift and increases in drag when in the simulated rain environment. Accompanying this was a reduction of the stall angle of attack by approximately 4 deg. The transient aerodynamic performance during transition from dry to wet steady-state conditions varied between a linear and a nonlinear transition.

  10. Wind Tunnel Aerodynamic Characteristics of a Transport-type Airfoil in a Simulated Heavy Rain Environment

    NASA Technical Reports Server (NTRS)

    Bezos, Gaudy M.; Dunham, R. Earl, Jr.; Gentry, Garl L., Jr.; Melson, W. Edward, Jr.

    1992-01-01

    The effects of simulated heavy rain on the aerodynamic characteristics of an NACA 64-210 airfoil section equipped with leading-and trailing-edge high-lift devices were investigated in the Langley 14- by 22-Foot Subsonic Tunnel. The model had a chord of 2.5 ft, a span of 8 ft, and was mounted on the tunnel centerline between two large endplates. Aerodynamic measurements in and out of the simulated rain environment were obtained for dynamic pressures of 30 and 50 psf and an angle-of-attack range of 0 to 20 degrees for the cruise configuration. The rain intensity was varied to produce liquid water contents ranging from 16 to 46 gm/cu m. The results obtained for various rain intensity levels and tunnel speeds showed significant losses in maximum lift capability and increases in drag for a given lift as the liquid water content was increased. The results obtained on the landing configuration also indicate a progressive decrease in the angle of attack at which maximum lift occurred and an increase in the slope of the pitching-moment curve as the liquid water content was increased. The sensitivity of test results to the effects of the water surface tension was also investigated. A chemical was introduced into the rain environment that reduced the surface tension of water by a factor of 2. The reduction in the surface tension of water did not significantly alter the level of performance losses for the landing configuration.

  11. 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 2; High Lift

    NASA Technical Reports Server (NTRS)

    McMillin, S. Naomi (Editor)

    1999-01-01

    NASA's High-Speed Research Program sponsored the 1998 Aerodynamic Performance Technical Review on February 9-13, in Los Angeles, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High-Lift, and Flight Controls. The review objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientists and engineers working HSCT aerodynamics. In particular, single- and multi-point optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program.

  12. 1999 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 2; High Lift

    NASA Technical Reports Server (NTRS)

    Hahne, David E. (Editor)

    1999-01-01

    NASA's High-Speed Research Program sponsored the 1999 Aerodynamic Performance Technical Review on February 8-12, 1999 in Anaheim, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in the areas of Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization), High Lift, and Flight Controls. The review objectives were to (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among die scientists and engineers working on HSCT aerodynamics. In particular, single and midpoint optimized HSCT configurations, HSCT high-lift system performance predictions, and HSCT simulation results were presented, along with executive summaries for all the Aerodynamic Performance technology areas. The HSR Aerodynamic Performance Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration. Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas of the HSR Program. This Volume 2/Part 2 publication covers the tools and methods development session.

  13. Fan Noise Source Diagnostic Test: Rotor Alone Aerodynamic Performance Results

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.; Jeracki, Robert J.; Woodward, Richard P.; Miller, Christopher J.

    2005-01-01

    The aerodynamic performance of an isolated fan or rotor alone model was measured in the NASA Glenn Research Center 9- by 15- Foot Low Speed Wind Tunnel as part of the Fan Broadband Source Diagnostic Test conducted at NASA Glenn. The Source Diagnostic Test was conducted to identify the noise sources within a wind tunnel scale model of a turbofan engine and quantify their contribution to the overall system noise level. The fan was part of a 1/5th scale model representation of the bypass stage of a current technology turbofan engine. For the rotor alone testing, the fan and nacelle, including the inlet, external cowl, and fixed area fan exit nozzle, were modeled in the test hardware; the internal outlet guide vanes located behind the fan were removed. Without the outlet guide vanes, the velocity at the nozzle exit changes significantly, thereby affecting the fan performance. As part of the investigation, variations in the fan nozzle area were tested in order to match as closely as possible the rotor alone performance with the fan performance obtained with the outlet guide vanes installed. The fan operating performance was determined using fixed pressure/temperature combination rakes and the corrected weight flow. The performance results indicate that a suitable nozzle exit was achieved to be able to closely match the rotor alone and fan/outlet guide vane configuration performance on the sea level operating line. A small shift in the slope of the sea level operating line was measured, which resulted in a slightly higher rotor alone fan pressure ratio at take-off conditions, matched fan performance at cutback conditions, and a slightly lower rotor alone fan pressure ratio at approach conditions. However, the small differences in fan performance at all fan conditions were considered too small to affect the fan acoustic performance.

  14. Comparison of the Aerodynamic Characteristics of Similar Models in Two Size Wind Tunnels at Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Springer, Anthony M.

    1998-01-01

    The aerodynamic characteristics of two similar models of a lifting body configuration were run in two transonic wind tunnels, one a 16 foot the other a 14-inch and are compared. The 16 foot test used a 2% model while the 14-inch test used a 0.7% scale model. The wind tunnel model configurations varied only in vertical tail size and an aft sting shroud. The results from these two tests compare the effect of tunnel size, Reynolds number, dynamic pressure and blockage on the longitudinal aerodynamic characteristics of the vehicle. The data accuracy and uncertainty are also presented. It was concluded from these tests that the data resultant from a small wind tunnel compares very well to that of a much larger wind tunnel in relation to total vehicle aerodynamic characteristics.

  15. Aerodynamic Performances of a Rectangular Variable Intake at Mach 5

    NASA Astrophysics Data System (ADS)

    Kojima, Takayuki; Taguchi, Hideyuki; Okai, Keiichi; Kobayashi, Hiroaki; Sato, Tetsuya

    Aerodynamic performances of a rectangular intake were investigated experimentally. After a tradeoff study of rectangular intakes whose operative Mach number is from 0 to 6, 20% external compression intake is selected as the best intake from the viewpoint of low number of actuators. Intake performances such as total pressure recovery and mass flow ratio are evaluated by wind tunnel tests. The free stream Mach number of the wind tunnel was M5.1. The size of the intake was 75mm in cowl capture height. Low ramp driving force was achieved by connecting links of the second ramp and third ramp. After the first wind tunnel test that is performed to evaluate the basic performance of the intake, the configuration of the intake is modified. Ramp length of the first ramp and the second ramp were changed to improve the total pressure recovery. Bleed from the second ramp is added. Seal mechanism between the variable ramps and the sidewall is modified. Total pressure recovery is improved from 9.9% to 21.7% by the modifications.

  16. Wake structure and aerodynamic characteristics of an auto-propelled pitching airfoil

    NASA Astrophysics Data System (ADS)

    Hanchi, S.; Benkherouf, T.; Mekadem, M.; Oualli, H.; Keirsbulck, L.; Labraga, L.

    2013-05-01

    In the present study, we investigate the wake configuration as well as the flow aerodynamic and propulsive characteristics of a system equipped with a nature-inspired propulsion system. The study focuses on the effect of a set of pitching frequency and amplitude values on the flow behavior for a symmetric foil performing pitching sinusoidal rolling oscillations. The viscous, non-stationary flow around the pitching foil is simulated using ANSYS FLUENT 13. The foil movement is reproduced using the dynamic mesh technique and an in-house developed UDF (User Define Function). Our results show the influence of the pitching frequency and the amplitude on the wake. We provide the mechanisms relating the system behavior to the applied forces. The frequency varies from 1 to 400Hz and the considered amplitudes are 18%, 24%, 30%, 37%, 53%, 82% and 114% of the foil chord.

  17. Low-speed longitudinal and lateral-directional aerodynamic characteristics of the X-31 configuration

    NASA Technical Reports Server (NTRS)

    Banks, Daniel W.; Gatlin, Gregory M.; Paulson, John W., Jr.

    1992-01-01

    An experimental investigation of a 19 pct. scale model of the X-31 configuration was completed in the Langley 14 x 22 Foot Subsonic Tunnel. This study was performed to determine the static low speed aerodynamic characteristics of the basic configuration over a large range of angle of attack and sideslip and to study the effects of strakes, leading-edge extensions (wing-body strakes), nose booms, speed-brake deployment, and inlet configurations. The ultimate purpose was to optimize the configuration for high angle of attack and maneuvering-flight conditions. The model was tested at angles of attack from -5 to 67 deg and at sideslip angles from -16 to 16 deg for speeds up to 190 knots (dynamic pressure of 120 psf).

  18. Aerodynamic characteristics of the ventilated design for flapping wing micro air vehicle.

    PubMed

    Zhang, G Q; Yu, S C M

    2014-01-01

    Inspired by superior flight performance of natural flight masters like birds and insects and based on the ventilating flaps that can be opened and closed by the changing air pressure around the wing, a new flapping wing type has been proposed. It is known that the net lift force generated by a solid wing in a flapping cycle is nearly zero. However, for the case of the ventilated wing, results for the net lift force are positive which is due to the effect created by the "ventilation" in reducing negative lift force during the upstroke. The presence of moving flaps can serve as the variable in which, through careful control of the areas, a correlation with the decrease in negative lift can be generated. The corresponding aerodynamic characteristics have been investigated numerically by using different flapping frequencies and forward flight speeds.

  19. Aerodynamic Characteristics of the Ventilated Design for Flapping Wing Micro Air Vehicle

    PubMed Central

    Zhang, G. Q.; Yu, S. C. M.

    2014-01-01

    Inspired by superior flight performance of natural flight masters like birds and insects and based on the ventilating flaps that can be opened and closed by the changing air pressure around the wing, a new flapping wing type has been proposed. It is known that the net lift force generated by a solid wing in a flapping cycle is nearly zero. However, for the case of the ventilated wing, results for the net lift force are positive which is due to the effect created by the “ventilation” in reducing negative lift force during the upstroke. The presence of moving flaps can serve as the variable in which, through careful control of the areas, a correlation with the decrease in negative lift can be generated. The corresponding aerodynamic characteristics have been investigated numerically by using different flapping frequencies and forward flight speeds. PMID:24683339

  20. Aerodynamic characteristics of a powered tilt-proprotor wind tunnel model

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Mineck, R. E.; Freeman, C. E.

    1976-01-01

    An investigation was conducted in the Langley V/STOL tunnel to determine the performance, stability and control, and rotor-wake interaction effects of a powered tilt-proprotor aircraft model with gimbal-hub rotors. Tests were conducted at representative flight conditions for hover, helicopter, transition, and airplane flight. Force and moment data were obtained for the complete model and for each of the two rotors. In addition to wind-speed variation, the angle of attack, angle of sideslip, rotor speed, rotor collective pitch, longitudinal cyclic pitch, rotor pylon angle, and configuration geometry were varied. The results, presented in graphical form, are available in tabular form to facilitate the validation of analytical methods of defining the aerodynamic characteristics of tilt-proprotor configurations.

  1. Investigation of aerodynamic characteristics of a hypersonic flow around bodies of revolution with a permeable tip

    NASA Astrophysics Data System (ADS)

    Sidnyaev, N. I.

    2007-03-01

    Results of experimental investigations of aerodynamic characteristics of models of high-velocity flying vehicles consisting of a combination of a blunt cone, a cylinder, and a conical tail fin are presented. The model forebody is cooled by porous blowing. The choice of such a configuration is determined by the necessity of optimizing the arrangement of high-velocity flying vehicles on the launcher and their aerodynamic characteristics under conditions of intense surface mass transfer (decrease in drag and heat transfer and increase in static and dynamic stability).

  2. Aerodynamic Performance Measurements for a Forward Swept Low Noise Fan

    NASA Technical Reports Server (NTRS)

    Fite, E. Brian

    2006-01-01

    One source of noise in high tip speed turbofan engines, caused by shocks, is called multiple pure tone noise (MPT's). A new fan, called the Quiet High Speed Fan (QHSF), showed reduced noise over the part speed operating range, which includes MPT's. The QHSF showed improved performance in most respects relative to a baseline fan; however, a partspeed instability discovered during testing reduced the operating range below acceptable limits. The measured QHSF adiabatic efficiency on the fixed nozzle acoustic operating line was 85.1 percent and the baseline fan 82.9 percent, a 2.2 percent improvement. The operating line pressure rise at design point rotational speed and mass flow was 1.764 and 1.755 for the QHSF and baseline fan, respectively. Weight flow at design point speed was 98.28 lbm/sec for the QHSF and 97.97 lbm/sec for the baseline fan. The operability margin for the QHSF approached 0 percent at the 75 percent speed operating condition. The baseline fan maintained sufficient margin throughout the operating range as expected. Based on the stage aerodynamic measurements, this concept shows promise for improved performance over current technology if the operability limitations can be solved.

  3. Supersonic aerodynamic characteristics of a tail-control cruciform maneuverable missile with and without wings

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.; Fournier, R. H.

    1978-01-01

    The aerodynamic characteristics for a winged and a wingless cruciform missile are examined. The body was an ogive-cylinder with a 3.5 caliber forebody; an overall length-to-diameter ratio of 11.667; and has cruciform tails that were trapexoidal in planform. Tests were made both with and without 72.9 deg cruciform delta wings. The investigation was made for Mach numbers from 1.50 to 4.63, roll attitudes of 0 and 45 deg, angles of attack from -40 to 22 deg, and tail control deflections from 10 to -40 deg. The purpose is to determine the influence of the aerodynamic behavior on the design choice for maneuverable missiles intended primarily for air-to-air or surface-to-surface missions. The results indicate that the winged missile with its more linear aerodynamic characteristics and higher lift-curve slope, should provide the highest maneuverability over a large operational range.

  4. Aerodynamic Characteristics of Two Rotary Wing UAV Designs

    NASA Technical Reports Server (NTRS)

    Jones, Henry E.; Wong, Oliver D.; Noonan, Kevin W.; Reis, Deane G.; Malovrh, Brendon D.

    2006-01-01

    This paper presents the results of an experimental investigation of two rotary-wing UAV designs. The primary goal of the investigation was to provide a set of interactional aerodynamic data for an emerging class of rotorcraft. The present paper provides an overview of the test and an introduction to the test articles, and instrumentation. Sample data in the form of a parametric study of fixed system lift and drag coefficient response to changes in configuration and flight condition for both rotor off and on conditions are presented. The presence of the rotor is seen to greatly affect both the character and magnitude of the response. The affect of scaled stores on body drag is observed to be dependent on body shape.

  5. AERODYNAMIC CHARACTERISTICS OF TWO ROTARY WING UAV DESIGNS

    NASA Technical Reports Server (NTRS)

    Jones, Henry E.; Wong, Oliver D.; Noonan, Kevin W.; Reis, Deane G.; Malovrh, Brendon D.

    2006-01-01

    This paper presents the results of an experimental investigation of two rotary-wing UAV designs. The primary goal of the investigation was to provide a set of interactional aerodynamic data for an emerging class of rotorcraft. The present paper provides an overview of the test and an introduction to the test articles, and instrumentation. Sample data in the form of a parametric study of fixed system lift and drag coefficient response to changes in configuration and flight condition for both rotor off and on conditions are presented. The presence of the rotor is seen to greatly affect both the character and magnitude of the response. The affect of scaled stores on body drag is observed to be dependent on body shape.

  6. Numerical investigations on the aerodynamic performance of wind turbine: Downwind versus upwind configuration

    NASA Astrophysics Data System (ADS)

    Zhou, Hu; Wan, Decheng

    2015-03-01

    Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory (NREL) phase VI wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface (AMI) method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.

  7. 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.

  8. Transonic aerodynamic characteristics of a supercritical-wing transport model with trailing-edge controls

    NASA Technical Reports Server (NTRS)

    Mann, M. J.; Langhans, R. A.

    1977-01-01

    The effects of wing trailing-edge control surfaces on the static transonic aerodynamic characteristics of a transport configuration with a supercritical wing were studied. The configuration was tested with both an area-ruled fuselage and a cylindrical fuselage. The Mach number range was from 0.80 to 0.96 and the angle of attack range was from -1 deg to 12 deg. The Reynolds number was 1,580,000 based on the mean aerodynamic chord. Tabular data are presented.

  9. Design of a piezoceramic-driven synthetic-jet actuator for aerodynamic performance improvement

    NASA Astrophysics Data System (ADS)

    Rusovici, Razvan; Offord, Casey; Honour, Ryan; Goto, Fumitaka; Louderback, Pierce; Phelps, Charley

    2008-03-01

    The interest in synthetic-jet actuators is elicited by their employment in fluid-control applications, including boundary-layer control, combustion control etc. These actuators are zero net-mass-flux devices, and generally consist of a diaphragm mounted to enclose a volume of fluid in a cavity. The diaphragm bends sinusoidally, and fluid is periodically absorbed into and ejected from the cavity through an orifice. The outflow entrains the fluid around it and establishes a mean jet flow at some distance from the source. Piezoceramic materials have been employed to drive the actuator diaphragm, especially when actuation frequencies are in excess of a few hundreds of hertz. The piezoceramic is glued directly to a silicon diaphragm. In combustion systems, improved turbulent mixing of air and fuel proper can significantly improve efficiency and reduce pollution. In boundary-layer separation control applications, synthetic-jets are used to improve aerodynamic performance by delaying separation and stall over the airfoil. The current work describes the modeling and design process of a piezoceramic-driven synthetic-jet actuator intended, amongst other applications, to improve the aerodynamic characteristics of a specific airfoil. A separate study consisting of numerical analyses performed with the aid of computational fluid dynamics (CFD) have been run to define the necessary performance parameters for the synthetic-jet actuator. The synthetic-jet actuator design task was achieved by running fluid-structure numerical analyses for various design parameters.

  10. Experimental investigation of the aerodynamic characteristics for a winged-cone concept

    NASA Technical Reports Server (NTRS)

    Phillips, W. Pelham; Brauckmann, Gregory J.; Micol, John R.; Woods, William C.

    1987-01-01

    Experimental longitudinal and lateral-directional aerodynamics were obtained for a generic aerodynamics were obtaiend for a generic winged-cone configuration having possible application as a transatmospheric vehicle concept. Data were obtained at Mach numbers from 0.6 to 20.0; Reynolds numbers, based on model length, between 2.5 and 5.3 million; and angles of attack from -4 to 20 deg. Results indicate a longitudinal center-of-pressure travel of about 23 percent of the fuselage length for the test Mach number range, with longitudinal instabilities noted at high-supersonic to hypersonic Mach numbers. These instabilities are coupled with directional instability at similar Mach numbers. Predictions with analytic codes, namely, the USAF DATCOM and the tangent-cone option of the Hypersonic Arbitrary Body Program, provided fair agreement with the experimental aerodynamic characteristics at low angles-of-attack.

  11. Aerodynamic characteristics of the Scout 133R vehicle determined from wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Abramson, F. B.; Muir, T. G., Jr.; Simmons, H. L.

    1972-01-01

    Bending moments and other associated parameters were measured on a Scout vehicle during a launch through high velocity horizontal winds. Comparison of the measured data with predictions revealed some unexplained discrepancies. Possible sources of error in the experimental data and predictions were considered; one of which is the predicted aerodynamic characteristics. A wind tunnel investigation was initiated, including supersonic force and pressure tests, to better define the aerodynamics. In addition to basic aerodynamic coefficients from the force test, detailed pressure and load distributions along the body were established from the pressure test. Pressure coefficients were integrated to determine normal load distributions, total normal force, and total pitching moment of the body. Comparison of the normal forces from pressure and force tests resulted in agreement within 15%. Comparison of pitching moment data from the two tests resulted in larger differences.

  12. Aerodynamic performance of aerofoils obtained from a geometric offset applied to a given initial aerofoil

    NASA Astrophysics Data System (ADS)

    Sousa, Diogo; Gamboa, Pedro; Melo, David

    2016-12-01

    Many studies concerning morphing aircraft concepts in which enhanced performance and increased energy efficiency are two of the main goals have been recently conducted. Some of those concepts deal with wing span changes. In line with those, in a variable-span wing of the telescopic type, the cross-sections of the sliding panels, whether be two, three or more, must be made geometrically compatible among them. This requirement serves two purposes: to minimize the aerofoils' geometric discontinuity which negatively affects wing drag and lift; and to provide a simple structural support between any two sliding panels. This paper describes the methodology employed to develop geometrically compatible aerofoils obtained from a constant geometric offset applied to a given initial aerofoil. This methodology is used to create inward offset aerofoils and outward offset aerofoils. The geometric and aerodynamic characteristics of the resulting offset aerofoils are compared with those of the original aerofoils. From the analysis of six different original aerofoils, strong trends in the geometric changes and in the aerodynamic characteristics of the resulting inward and outward offset aerofoils are observed. Ultimately, this study can help a telescopic wing designer decide whether an inward or an outward offset aerofoil is more appropriate for the specific design at hand.

  13. Building Integrated Active Flow Control: Improving the Aerodynamic Performance of Tall Buildings Using Fluid-Based Aerodynamic Modification

    NASA Astrophysics Data System (ADS)

    Menicovich, David

    material and energy consumption profiles of tall building. To date, the increasing use of light-weight and high-strength materials in tall buildings, with greater flexibility and reduced damping, has increased susceptibility to dynamic wind load effects that limit the gains afforded by incorporating these new materials. Wind, particularly fluctuating wind and its interaction with buildings induces two main responses; alongwind - in the direction of the flow and crosswind - perpendicular to the flow. The main risk associated with this vulnerability is resonant oscillations induced by von-Karman-like vortex shedding at or near the natural frequency of the structure caused by flow separation. Dynamic wind loading effects often increase with a power of wind speed greater than 3, thus increasingly, tall buildings pay a significant price in material to increase the natural frequency and/or the damping to overcome this response. In particular, crosswind response often governs serviceability (human habitability) design criteria of slender buildings. Currently, reducing crosswind response relies on a Solid-based Aerodynamic Modification (SAM), either by changing structural or geometric characteristics such as the tower shape or through the addition of damping systems. While this approach has merit it has two major drawbacks: firstly, the loss of valuable rentable areas and high construction costs due to increased structural requirements for mass and stiffness, further contributing towards the high consumption of non-renewable resources by the commercial building sector. For example, in order to insure human comfort within an acceptable range of crosswind response induced accelerations at the top of a building, an aerodynamically efficient plan shape comes at the expense of floor area. To compensate for the loss of valuable area compensatory stories are required, resulting in an increase in wind loads and construction costs. Secondly, a limited, if at all, ability to adaptively

  14. The Aerodynamic Performance of the Houck Configuration Flow Guides

    DTIC Science & Technology

    2007-06-01

    Vortices.............................................................................................13 2.5 Winglets ...associated with the Houck configuration. This includes winglets , biplanes, and joined-wing aircraft. After that the chapter will discuss the evolution...efficiency factor (e = 1 for elliptical wing). 2.5 Winglets A winglet is best described by Jean Chattot’s quote: “ Winglets are aerodynamic components

  15. The Aerodynamic Performance of the 24 Inch Houck Configuration

    DTIC Science & Technology

    2007-03-01

    8 2.5 Winglets ... Winglets “ Winglets are aerodynamic components, placed at the tip of a wing to improve its efficiency during cruise” (6). The purpose of the winglet ...reduction in downwash, and therefore the induced drag (20; 11:1). Properly designed winglets can reduce overall drag, increase lift, provide added stability

  16. Computations of Aerodynamic Performance Databases Using Output-Based Refinement

    NASA Technical Reports Server (NTRS)

    Nemec, Marian; Aftosmis, Michael J.

    2009-01-01

    Objectives: Handle complex geometry problems; Control discretization errors via solution-adaptive mesh refinement; Focus on aerodynamic databases of parametric and optimization studies: 1. Accuracy: satisfy prescribed error bounds 2. Robustness and speed: may require over 105 mesh generations 3. Automation: avoid user supervision Obtain "expert meshes" independent of user skill; and Run every case adaptively in production settings.

  17. Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

    NASA Astrophysics Data System (ADS)

    Yongfeng, DENG; Jian, JIANG; Xianwei, HAN; Chang, TAN; Jianguo, WEI

    2017-04-01

    The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.

  18. Unsteady Aerodynamic Effects on the Flight Characteristics of an F-16XL Configuration

    NASA Technical Reports Server (NTRS)

    Wang, Zhongjun; Lan, C. Edward; Brandon, Jay M.

    2000-01-01

    Unsteady aerodynamic models based on windtunnel forced oscillation test data and analyzed with a fuzzy logic algorithm arc incorporated into an F-16XL flight simulation code. The reduced frequency needed in the unsteady models is numerically calculated by using a limited prior time history of state variables in a least-square sense. Numerical examples arc presented to show the accuracy of the calculated reduced frequency. Oscillatory control inputs are employed to demonstrate the differences in the flight characteristics based on unsteady and quasi-steady aerodynamic models. Application of the unsteady aerodynamic models is also presented and the results are compared with one set of F16XIL longitudinal maneuver flight data. It is shown that the main differences in dynamic response are in the lateral-directional characteristics, with the quasi-steady model being more stable than the flight vehicle, while the unsteady model being more unstable. Similar conclusions can also be made in a simulated rapid sideslipping roll. To improve unsteady aerodynamic modeling, it is recommended to acquire test data with coupled motions in pitch, roll and yaw.

  19. Characteristic boundary conditions for three-dimensional transonic unsteady aerodynamics

    NASA Technical Reports Server (NTRS)

    Whitlow, W., Jr.

    1984-01-01

    Characteristic far-field boundary conditions for the three-dimensional unsteady transonic small disturbance potential equation have been developed. The boundary conditions were implemented in the XTRAN3S finite difference code and tested for a flat plate rectangular wing with a pulse in angle of attack; the freestream Mach number was 0.85. The calculated force response shows that the characteristic boundary conditions reduce disturbances that are reflected from the computational boundaries.

  20. Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

    SciTech Connect

    Robert J. Englar

    2000-06-19

    Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model.

  1. Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

    NASA Astrophysics Data System (ADS)

    Polanský, Jiří; Kalmár, László; Gášpár, Roman

    2013-12-01

    The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.

  2. Aerodynamic characteristics of a propeller-powered high-lift semispan wing

    NASA Technical Reports Server (NTRS)

    Gentry, Garl L., Jr.; Takallu, M. A.; Applin, Zachary T.

    1994-01-01

    A small-scale semispan high-lift wing-flap system equipped under the wing with a turboprop engine assembly was tested in the LaRC 14- by 22-Foot Subsonic Tunnel. Experimental data were obtained for various propeller rotational speeds, nacelle locations, and nacelle inclinations. To isolate the effects of the high lift system, data were obtained with and without the flaps and leading-edge device. The effects of the propeller slipstream on the overall longitudinal aerodynamic characteristics of the wing-propeller assembly were examined. Test results indicated that the lift coefficient of the wing could be increased by the propeller slipstream when the rotational speed was increased and high-lift devices were deployed. Decreasing the nacelle inclination (increased pitch down) enhanced the lift performance of the system much more than varying the vertical or horizontal location of the nacelle. Furthermore, decreasing the nacelle inclination led to higher lift curve slope values, which indicated that the powered wing could sustain higher angles of attack near maximum lift performance. Any lift augmentation was accompanied by a drag penalty due to the increased wing lift.

  3. Computer programs for calculating the static longitudinal aerodynamic characteristics of wing-body-tail configurations

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Goodwin, F. K.; Dillenius, M. F. E.; Kline, D. M.

    1975-01-01

    Four computer programs developed to calculate the longitudinal aerodynamic characteristics of wing-body and wing-body-tail combinations are presented. The R1307 program is based on a linear method and is limited to the small range of angles of attack for which the lift and moment characteristics of wings and bodies are linear with angle of attack. The CRSFLW program is based on a crossflow method of predicting the forces and moments on bodies alone or wing-body combinations over a large angle of attack range. The SUBSON program predicts the longitudinal aerodynamic characteristics of wing-body-tail combinations at subsonic speeds and at angles of attack for which symmetrical pairs of vortices are shed from the body nose and the leading and side edges of the lifting surfaces. Program SUPSON predicts the longitudinal aerodynamic characteristics of wing-body-tail combinations at supersonic speeds in the same angle-of-attack range. A description of the use of each program, instructions for preparation of input, a description of the output, program listings, and sample cases for each program are included.

  4. 1999 NASA High-Speed Research Program Aerodynamic Performance Workshop. Volume 2; High Lift

    NASA Technical Reports Server (NTRS)

    Hahne, David E. (Editor)

    1999-01-01

    The High-Speed Research Program sponsored the NASA High-Speed Research Program Aerodynamic Performance Review on February 8-12, 1999 in Anaheim, California. The review was designed to bring together NASA and industry High-Speed Civil Transport (HSCT) Aerodynamic Performance technology development participants in areas of: Configuration Aerodynamics (transonic and supersonic cruise drag prediction and minimization) and High-Lift. The review objectives were to: (1) report the progress and status of HSCT aerodynamic performance technology development; (2) disseminate this technology within the appropriate technical communities; and (3) promote synergy among the scientist and engineers working HSCT aerodynamics. The HSR AP Technical Review was held simultaneously with the annual review of the following airframe technology areas: Materials and Structures, Environmental Impact, Flight Deck, and Technology Integration Thus, a fourth objective of the Review was to promote synergy between the Aerodynamic Performance technology area and the other technology areas within the airframe element of the HSR Program. This Volume 2/Part 1 publication presents the High-Lift Configuration Development session.

  5. Experimental quiet engine program aerodynamic performance of Fan C

    NASA Technical Reports Server (NTRS)

    Giffin, R. G.; Parker, D. E.; Dunbar, L. W.

    1972-01-01

    This report presents the aerodynamic component test results of Fan C, a high-bypass-ratio, low-aerodynamic-loading, 1550 feet per second (472.4 m/sec), single-stage fan, which was designed and tested as part of the NASA Experimental Quiet Engine Program. The fan was designed to deliver a bypass pressure ratio of 1.60 with an adiabatic efficiency of 84.2 percent at a total fan flow of 915 lb/sec (415.0 kg/sec). It was tested with and without inlet distortion. A bypass total-pressure ratio of 1.61 and an adiabatic efficiency of 83.9 percent at a total fan flow of 921 lb/sec (417.8 kg/sec) were actually achieved. An operating margin in excess of 14.6 percent was demonstrated at design speed.

  6. Experimental study of aerodynamic characteristics of a reentry vehicle on a setup with free oscillations at supersonic velocities

    NASA Astrophysics Data System (ADS)

    Adamov, N. P.; Kharitonov, A. M.; Chasovnikov, E. A.; Dyad'kin, A. A.; Krylov, A. N.; Aleksandrov, E. N.

    2016-11-01

    A setup with free oscillations containing a transverse sting for holding the test model and possible test regimes are described. The method of testing and data processing is presented. Aerodynamic characteristics of the pitching moment of the model in a wide range of Mach numbers are obtained. Comparisons of quasi-steady data with numerical predictions and of damping derivatives with those obtained previously in tests of the model mounted on the base sting and with calculated results are performed. The model is found to be statically and dynamically stable except for regimes with M = 1.75 and 2.25, where nondecaying oscillations are excited.

  7. Experimental Hypersonic Aerodynamic Characteristics of the 2001 Mars Surveyor Precision Lander with Flap

    NASA Technical Reports Server (NTRS)

    Horvath, Thomas J.; OConnell, Tod F.; Cheatwood, F. McNeil; Prabhu, Ramadas K.; Alter, Stephen J.

    2002-01-01

    Aerodynamic wind-tunnel screening tests were conducted on a 0.029 scale model of a proposed Mars Surveyor 2001 Precision Lander (70 deg half angle spherically blunted cone with a conical afterbody). The primary experimental objective was to determine the effectiveness of a single flap to trim the vehicle at incidence during a lifting hypersonic planetary entry. The laminar force and moment data, presented in the form of coefficients, and shock patterns from schlieren photography were obtained in the NASA Langley Aerothermodynamic Laboratory for post-normal shock Reynolds numbers (based on forebody diameter) ranging from 2,637 to 92,350, angles of attack ranging from 0 tip to 23 degrees at 0 and 2 degree sideslip, and normal-shock density ratios of 5 and 12. Based upon the proposed entry trajectory of the 2001 Lander, the blunt body heavy gas tests in CF, simulate a Mach number of approximately 12 based upon a normal shock density ratio of 12 in flight at Mars. The results from this experimental study suggest that when traditional means of providing aerodynamic trim for this class of planetary entry vehicle are not possible (e.g. offset c.g.), a single flap can provide similar aerodynamic performance. An assessment of blunt body aerodynamic effects attributed to a real gas were obtained by synergistic testing in Mach 6 ideal-air at a comparable Reynolds number. From an aerodynamic perspective, an appropriately sized flap was found to provide sufficient trim capability at the desired L/D for precision landing. Inviscid hypersonic flow computations using an unstructured grid were made to provide a quick assessment of the Lander aerodynamics. Navier-Stokes computational predictions were found to be in very good agreement with experimental measurement.

  8. Computational studies on small wind turbine performance characteristics

    NASA Astrophysics Data System (ADS)

    Karthikeyan, N.; Suthakar, T.

    2016-10-01

    To optimize the selection of suitable airfoils for small wind turbine applications, computational investigation on aerodynamic characteristics of low Re airfoils MID321a, MID321d, SG6040, SG6041, SG6042 and SG6043 are carried out for the Reynolds number range of (0.5- 2)×105. The BEM method is used to determine the power coefficient of the rotor from the airfoil characteristics; in addition, the blade parameters like chord and twist are also determined. The newly designed MID321a airfoil shows better aerodynamic performance and maximum power coefficient as compared with other investigated airfoils for wider operating ranges.

  9. Aerodynamic Performance and Turbulence Measurements in a Turbine Vane Cascade

    NASA Technical Reports Server (NTRS)

    Boyle, Robert J.; Lucci, Barbara L.; Senyitko, Richard G.

    2002-01-01

    Turbine vane aerodynamics were measured in a three vane linear cascade. Surface pressures and blade row losses were obtained over a range of Reynolds and Mach number for three levels of turbulence. Comparisons are made with predictions using a quasi-3D Navier-Stokes analysis. Turbulence intensity measurement were made upstream and downstream of the vane. The purpose of the downstream measurements was to determine how the turbulence was affected by the strong contraction through 75 deg turning.

  10. The Aerodynamic Characteristics of a Slotted Clark Y Wing as Affected by the Auxiliary Airfoil Position

    NASA Technical Reports Server (NTRS)

    Wenzinger, Carl J; Shortal, Joseph A

    1932-01-01

    Aerodynamic force tests on a slotted Clark Y wing were conducted in a vertical wind tunnel to determine the best position for a given auxiliary airfoil with respect to the main wing. A systematic series of 100 changes in location of the auxiliary airfoil were made to cover all the probable useful ranges of slot gap, slot width, and slot depth. The results of the investigation may be applied to the design of automatic or controlled slots on wings with geometric characteristics similar to the wing tested. The best positions of the auxiliary airfoil were covered by the range of the tests, and the position for desired aerodynamic characteristics may easily be obtained from charts prepared especially for the purpose.

  11. The Practical Calculation of the Aerodynamic Characteristics of Slender Finned Vehicles

    NASA Technical Reports Server (NTRS)

    Barrowman, James S.

    1967-01-01

    The basic objective of this thesis is to provide a practical method of computing the aerodynamic characteristics of slender finned vehicles such as sounding rockets, high speed bombs, and guided missiles. The aerodynamic characteristics considered are the normal force coefficient derivative, c(sub N(sub alpha)); center of pressure, bar-X; roll forcing moment coefficient derivative, c(sub l(sub delta)); roll damping moment coefficient derivative, c(sub l(sub p)); pitch damping moment coefficient derivative, c(sub mq); and the drag coefficient, c (sub D). Equations are determined for both subsonic and supersonic flow. No attempts is made to analyze the transonic region. The general configuration to which the relations are applicable is a slender axisymmetric body having three or four fins.

  12. Aerodynamic characteristics at Mach 6 of a wing-body concept for a hypersonic research airplane

    NASA Technical Reports Server (NTRS)

    Dillon, J. L.; Pittman, J. L.

    1978-01-01

    The static aerodynamic characteristics of a 1/30 scale model of a wing-body concept for a high speed research airplane were investigated in the Langley 20 inch Mach six tunnel. The investigation consisted of configuration buildup from the basic body by adding a wing, center vertical tail, three-module scramjet, and six-module scramjet engine. The test Mach number was six at a Reynolds number, based on model fuselage length, of about 13,700,000. The test angle-of-attack range was 4 to 20 D at constant angles of sideslip of 0, 2, and 4 deg. The elevons were deflected from 10 to -15 D for pitch control. Roll and yaw control were investigated. Experimental aerodynamic characteristics are compared with analytical elements.

  13. Calculation of aerodynamic characteristics of airplane configurations at high angles of attack

    NASA Technical Reports Server (NTRS)

    Tseng, J. B.; Lan, C. Edward

    1988-01-01

    Calculation of longitudinal and lateral directional aerodynamic characteristics of airplanes by the VORSTAB code is examined. The numerical predictions are based on the potential flow theory with corrections of high angle of attack phenomena; namely, vortex flow and boundary layer separation effects. To account for the vortex flow effect, vortex lift, vortex action point, augmented vortex lift and vortex breakdown effect through the method of suction analogy are included. The effect of boundary layer separation is obtained by matching the nonlinear section data with the three dimensional lift characteristics iteratively. Through correlation with results for nine fighter configurations, it is concluded that reasonably accurate prediction of longitudinal and static lateral directional aerodynamics can be obtained with the VORSTAB code up to an angle of attack at which wake interference and forebody vortex effect are not important. Possible reasons for discrepancy at higher angles of attack are discussed.

  14. Aerodynamic characteristics of supersonic fighter airplane configurations based on Soviet design concepts

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.; Fournier, R. H.; Lamb, M.

    1977-01-01

    The aerodynamic, stability, and control characteristics of several supersonic fighter airplane concepts are examined. The configurations, which are based on Soviet design concepts, include fixed-wing aircraft having delta wings, swept wings, and trapezoidal wings, and a variable wing-sweep aircraft. Each concept employs aft tail controls. The concepts vary from lightweight, single-engine, air superiority, point interceptor, or ground attack types to larger twin-engine interceptor and reconnaissance designs. Analytical and experimental results indicate that careful application of the transonic or supersonic area rule can provide nearly optimum shaping for minimum drag for a specified Mach number requirement. In addition, through the proper location of components and the exploitation of interference flow fields, the concepts provide linear pitching moment characteristics, high control effectiveness, and reasonably small variations in aerodynamic center location with a resulting high potential for maneuvering capability.

  15. Aerodynamic characteristics of the standard dynamics model in coning motion at Mach 0.6

    NASA Technical Reports Server (NTRS)

    Jermey, C.; Schiff, L. B.

    1985-01-01

    A wind tunnel test was conducted on the Standard Dynamics Model (a simplified generic fighter aircraft shape) undergoing coning motion at Mach 0.6. Six component force and moment data are presented for a range of angle of attack, sideslip, and coning rates. At the relatively low non-dimensional coning rate employed (omega b/2V less than or equal to 0.04), the lateral aerodynamic characteristics generally show a linear variation with coning rate.

  16. Unsteady aerodynamic interaction effects on turbomachinery blade life and performance

    NASA Technical Reports Server (NTRS)

    Adamczyk, John J.

    1992-01-01

    This paper is an attempt to address the impact of a class of unsteady flows on the life and performance of turbomachinery blading. These class of flows to be investigated are those whose characteristic frequency is an integral multiple of rotor shaft speed. Analysis of data recorded downstream of a compressor and turbine rotor will reveal that this class of flows can be highly three-dimensional and may lead to the generation of secondary flows within downstream blading. By explicitly accounting for these unsteady flows in the design of turbomachinery blading for multistage applications, it may be possible to bring about gains in performance and blade life.

  17. Experimental Aerodynamic Characteristics of an Oblique Wing for the F-8 OWRA

    NASA Technical Reports Server (NTRS)

    Kennelly, Robert A., Jr.; Carmichael, Ralph L.; Smith, Stephen C.; Strong, James M.; Kroo, Ilan M.

    1999-01-01

    An experimental investigation was conducted during June-July 1987 in the NASA Ames 11-Foot Transonic Wind Tunnel to study the aerodynamic performance and stability and control characteristics of a 0.087-scale model of an F-8 airplane fitted with an oblique wing. This effort was part of the Oblique Wing Research Aircraft (OWRA) program performed in conjunction with Rockwell International. The Ames-designed, aspect ratio 10.47, tapered wing used specially designed supercritical airfoils with 0.14 thickness/chord ratio at the root and 0.12 at the 85% span location. The wing was tested at two different mounting heights above the fuselage. Performance and longitudinal stability data were obtained at sweep angles of 0deg, 30deg, 45deg, 60deg, and 65deg at Mach numbers ranging from 0.30 to 1.40. Reynolds number varied from 3.1 x 10(exp 6)to 5.2 x 10(exp 6), based on the reference chord length. Angle of attack was varied from -5deg to 18deg. The performance of this wing is compared with that of another oblique wing, designed by Rockwell International, which was tested as part of the same development program. Lateral-directional stability data were obtained for a limited combination of sweep angles and Mach numbers. Sideslip angle was varied from -5deg to +5deg. Landing flap performance was studied, as were the effects of cruise flap deflections to achieve roll trim and tailor wing camber for various flight conditions. Roll-control authority of the flaps and ailerons was measured. A novel, deflected wing tip was evaluated for roll-control authority at high sweep angles.

  18. Numerical Simulations of the Steady and Unsteady Aerodynamic Characteristics of a Circulation Control Wing Airfoil

    NASA Technical Reports Server (NTRS)

    Liu, Yi; Sankar, Lakshmi N.; Englar, Robert J.; Ahuja, Krishan K.

    2003-01-01

    The aerodynamic characteristics of a Circulation Control Wing (CCW) airfoil have been numerically investigated, and comparisons with experimental data have been made. The configuration chosen was a supercritical airfoil with a 30 degree dual-radius CCW flap. Steady and pulsed jet calculations were performed. It was found that the use of steady jets, even at very small mass flow rates, yielded a lift coefficient that is comparable or superior to conventional high-lift systems. The attached flow over the flap also gave rise to lower drag coefficients, and high L/D ratios. Pulsed jets with a 50% duty cycle were also studied. It was found that they were effective in generating lift at lower reduced mass flow rates compared to a steady jet, provided the pulse frequency was sufficiently high. This benefit was attributable to the fact that the momentum coefficient of the pulsed jet, during the portions of the cycle when the jet was on, was typically twice as much as that of a steady jet.

  19. Axial compressor blade design for desensitization of aerodynamic performance and stability to tip clearance

    NASA Astrophysics Data System (ADS)

    Erler, Engin

    region, this approach would entail a nominal performance penalty. Therefore, the chosen rotor design philosophy aims to keep the spanwise loading constant to avoid trading performance for desensitization. The rotor designs that resulted from this exercise are simulated in ANSYS CFX at different tip clearance sizes. The change in their performance with respect to tip clearance size (sensitivity) is compared both on an integral level in terms of pressure ratio and adiabatic efficiency, as well as on a detailed level in terms of aerodynamic losses and blockage associated with tip clearance flow. The sensitivity of aerodynamic stability is evaluated either directly through the simulations of the rotor characteristics up to the stall point (expensive in time and resources) for a few designs or indirectly through the position of the interface between the incoming and tip clearance flow with respect to the rotor leading edge plane. The latter approach is based on a generally observed stall criteria in modern axial compressors. The rotor designs are then assessed according to their sensitivity in comparison to that of the reference rotor design to detect features that can explain the trend in sensitivity to tip clearance size. These features can then be validated and the associated flow mechanisms explained through numerical simulations and modelling. Analysis of the database from the rotor parametric study shows that the observed trend in sensitivity cannot be explained by the shifting of the aerodynamic loading along the blade chord, as initially hypothesized based on the literature review. Instead, two flow features are found to reduce sensitivity of performance and stability to tip clearance, namely an increase in incoming meridional momentum in the tip region and a reduction/elimination of double leakage flow. Double leakage flow is the flow that exits the tip clearance of one blade and proceeds into the clearance of the adjacent blade rather than convecting downstream out

  20. Evaluation of VSAERO in prediction of aerodynamic characteristics of helicopter hub fairings

    NASA Technical Reports Server (NTRS)

    Louie, Alexander

    1989-01-01

    A low-order panel code, VSAERO, was used to predict the aerodynamic characteristics of helicopter hub fairings. Since the simulation of this kind of bluff body by VSAERO was not documented before, the VSAERO solutions were correlated with experimental data to establish their validity. The validation process revealed that simulation of the aerodynamic environment around a hub fairing was sensitive to several modeling parameters. Some of these parameters are body and wake panels arrangement, streamwise and spanwise separation location, and the most prominent one-the wake modeling. Three wake models were used: regular wake, separated wake, and jet model. The regular wake is a wake with negligible thickness (thin wake). It is represented by a single vortex sheet. The separated wake and the jet model in the present application are wakes with finite thickness (thick wake). They consist of a vortex sheet enclosing a region of low-energy flow. The results obtained with the reqular wake were marginally acceptable for sharp-edged hub fairings. For all other cases under consideration, the jet model results correlated slightly better. The separated wake, which seemed to be the most appropriate model, caused the solution to diverge. While the regular wake was straight-forward to apply in simulations, the jet model was not. It requires the user to provide information about the doublet strength gradient on wake panels by guessing the efflux velocities at the wake shedding location. In summary, VSAERO neither predicts accurately the aerodynamic characteristics of helicopter hub fairings nor was cost effective.

  1. Flight Test Determined Aerodynamics Force and Moment Characteristics of the X-43A Research Vehicle at Mach 7.0

    NASA Technical Reports Server (NTRS)

    Davis, Mark C.; White, J. Terry

    2006-01-01

    The second flight of the HYPER-X Program afforded a unique opportunity to determine the aerodynamic force and moment characteristics of an airframe integrated scramjet powered aircraft in hypersonic flight. These data were gathered via a repeated series of pitch, yaw, and roll doublets, frequency sweeps, and pull-up/push-over maneuvers performed throughout the X-43A cowl-closed descent phase. The subject flight research maneuvers were conducted in a Mach number range of 6.8 to 0.95 at altitudes from 92,000 ft to sea level. In this flight regime, the dynamic pressure varied from 1300 psf to 400 psf with angle-of-attack ranging from 0 deg to 14 deg. The flight-extracted aerodynamics were compared with pre-flight predictions based on wind tunnel test data. The X-43A flight-derived axial force was found to be 10 to 15 percent higher than prediction. Under-predictions of similar magnitude were observed for the normal force. For Mach numbers greater than 4, the X-43A flight-derived stability and control characteristics resulted in larger than predicted static margins, with the largest discrepancy approximately 5-inches forward along the X(CG) at Mach 6. This would result in less static margin in pitch. The X-43A predicted lateral-directional stability and control characteristics matched well with flight data when allowance was made for the high uncertainty in angle-of-sideslip.

  2. Flight-Test-Determined Aerodynamic Force and Moment Characteristics of the X-43A at Mach 7.0

    NASA Technical Reports Server (NTRS)

    Davis. Marl C.; White, J. Terry

    2006-01-01

    The second flight of the Hyper-X program afforded a unique opportunity to determine the aerodynamic force and moment characteristics of an airframe-integrated scramjet-powered aircraft in hypersonic flight. These data were gathered via a repeated series of pitch, yaw, and roll doublets; frequency sweeps; and pushover-pullup maneuvers performed throughout the X-43A cowl-closed descent. Maneuvers were conducted at Mach numbers of 6.80 to 0.95 and altitudes from 92,000 ft msl to sea level. The dynamic pressure varied from 1300 psf to 400 psf with the angle of attack ranging from 0 deg to 14 deg. The flight-extracted aerodynamics were compared with preflight predictions based on wind-tunnel-test data. The X-43A flight-derived axial force was found to be 10 percent to 15 percent higher than prediction. Under-predictions of similar magnitude were observed for the normal force. For Mach numbers above 4.0, the flight-derived stability and control characteristics resulted in larger-than-predicted static margins, with the largest discrepancy approximately 5 in. forward along the x-axis center of gravity at Mach 6.0. This condition would result in less static margin in pitch. The predicted lateral-directional stability and control characteristics matched well with flight data when allowance was made for the high uncertainty in angle of sideslip.

  3. X-43A Flight-Test-Determined Aerodynamic Force and Moment Characteristics at Mach 7.0

    NASA Technical Reports Server (NTRS)

    Davis, Mark C.; White, J. Terry

    2008-01-01

    The second flight of the Hyper-X program afforded a unique opportunity to determine the aerodynamic force and moment characteristics of an airframe-integrated scramjet-powered aircraft in hypersonic flight. These data were gathered via a repeated series of pitch, yaw, and roll doublets, frequency sweeps, and pushover-pullup maneuvers performed throughout the X-43A cowl-closed descent. Maneuvers were conducted at Mach numbers of 6.80-0.95 and at altitudes from 92,000 ft mean sea level to sea level. The dynamic pressure varied from 1300 to 400 psf with the angle of attack ranging from 0 to 14 deg. The flight-extracted aerodynamics were compared with preflight predictions based on wind-tunnel test data. The X-43A flight-derived axial force was found to be 10-15%higher than prediction. Underpredictions of similar magnitude were observed for the normal force. For Mach numbers above 4.0, the flight-derived stability and control characteristics resulted in larger-than-predicted static margins, with the largest discrepancy approximately 5 in. forward along the x-axis center of gravity at Mach 6.0. This condition would result in less static margin in pitch. The predicted lateral-directional stability and control characteristics matched well with flight data when allowance was made for the high uncertainty in angle of sideslip.

  4. An experimental and theoretical analysis of the aerodynamic characteristics of a biplane-winglet configuration. M.D. Thesis

    NASA Technical Reports Server (NTRS)

    Gall, P. D.

    1984-01-01

    Improving the aerodynamic characteristics of an airplane with respect to maximizing lift and minimizing induced and parasite drag are of primary importance in designing lighter, faster, and more efficient aircraft. Previous research has shown that a properly designed biplane wing system can perform superiorly to an equivalent monoplane system with regard to maximizing the lift-to-drag ratio and efficiency factor. Biplanes offer several potential advantages over equivalent monoplanes, such as a 60-percent reduction in weight, greater structural integrity, and increased roll response. The purpose of this research is to examine, both theoretically and experimentally, the possibility of further improving the aerodynamic characteristics of the biplanes configuration by adding winglets. Theoretical predictions were carried out utilizing vortex-lattice theory, which is a numerical method based on potential flow theory. Experimental data were obtained by testing a model in the Pennsylvania State University's subsonic wind tunnel at a Reynolds number of 510,000. The results showed that the addition of winglets improved the performance of the biplane with respect to increasing the lift-curve slope, increasing the maximum lift coefficient, increasing the efficiency factor, and decreasing the induced drag. A listing of the program is included in the Appendix.

  5. Assessment Of The Aerodynamic And Aerothermodynamic Performance Of The USV-3 High-Lift Re-Entry Vehicle

    NASA Astrophysics Data System (ADS)

    Pezzella, Giuseppe; Richiello, Camillo; Russo, Gennaro

    2011-05-01

    This paper deals with the aerodynamic and aerothermodynamic trade-off analysis carried out with the aim to design a hypersonic flying test bed (FTB), namely USV3. Such vehicle will have to be launched with a small expendable launcher and shall re-enter the Earth atmosphere allowing to perform several experiments on critical re-entry phenomena. The demonstrator under study is a re-entry space glider characterized by a relatively simple vehicle architecture able to validate hypersonic aerothermodynamic design database and passenger experiments, including thermal shield and hot structures. Then, a summary review of the aerodynamic characteristics of two FTB concepts, compliant with a phase-A design level, has been provided hereinafter. Indeed, several design results, based both on engineering approach and computational fluid dynamics, are reported and discussed in the paper.

  6. A program to compute three-dimensional subsonic unsteady aerodynamic characteristics using the doublet lattice method, L216 (DUBFLEX). Volume 2: Supplemental system design and maintenance document

    NASA Technical Reports Server (NTRS)

    Harrison, B. A.; Richard, M.

    1979-01-01

    The information necessary for execution of the digital computer program L216 on the CDC 6600 is described. L216 characteristics are based on the doublet lattice method. Arbitrary aerodynamic configurations may be represented with combinations of nonplanar lifting surfaces composed of finite constant pressure panel elements, and axially summetric slender bodies composed of constant pressure line elements. Program input consists of configuration geometry, aerodynamic parameters, and modal data; output includes element geometry, pressure difference distributions, integrated aerodynamic coefficients, stability derivatives, generalized aerodynamic forces, and aerodynamic influence coefficient matrices. Optionally, modal data may be input on magnetic field (tape or disk), and certain geometric and aerodynamic output may be saved for subsequent use.

  7. Experimental quiet engine program aerodynamic performance of fan A

    NASA Technical Reports Server (NTRS)

    Giffin, R. G.; Parker, D. E.; Dunbar, L. W.

    1971-01-01

    The aerodynamic component test results are presented of fan A, one of two high-bypass-ratio, 1160 feet per second single-stage fans, which was designed and tested as part of the NASA Experimental Quiet Engine Program. This fan was designed to deliver a bypass pressure ratio of 1.50 with an adiabatic efficiency of 86.5% at a total fan flow of 950 lb/sec. It was tested with and without inlet flow distortion. A bypass total-pressure ratio of 1.52 and an adiabatic efficiency of 88.3% at a total fan flow of 962 lb/sec were actually achieved. An operating margin of 12.4% was demonstrated at design speed.

  8. Aerodynamic Characteristics of a Flying-Boat Hull Having a Length-Beam Ratio of 15, TED No. NACA 2206

    NASA Technical Reports Server (NTRS)

    Riebe, John M.; Naeseth, Rodger L.

    1951-01-01

    An investigation was made in the Langley 300 MPH 7- by 10-foot tunnel to determine the aerodynamic characteristics of a flying-boat hull of a length-beam ratio of 15 in the presence of a wing. The investigation was an extension of previous tests made on hulls of length-beam ratios of 6, 9, and 12; these hulls were designed to have approximately the same hydrodynamic performance with respect to spray and resistance characteristics. Comparison with the previous investigation at lower length-beam ratios indicated a reduction in minimum drag coefficients of 0.0006 (10 peroent)with fixed transition when the length-beam ratio was extended from 12 to 15. As with the hulls of lower length-beam ratio, the drag reduction with a length-beam ratio of 15 occurred throughout the range of angle of attack tested and the angle of attack for minimum drag was in the range from 2deg to 3deg. Increasing the length-beam ratio from 12 to 15 reduced the hull longitudinal instability by an mount corresponding to an aerodynamic-center shift of about 1/2 percent of the mean aerodynamic chord of the hypothetical flying boat. At an angle of attack of 2deg, the value of the variation of yawing-moment coefficient with angle of yaw for a length-beam ratio of 15 was 0.00144, which was 0.00007 larger than the value for a length-beam ratio of 12.

  9. An analysis for high speed propeller-nacelle aerodynamic performance prediction. Volume 2: User's manual

    NASA Technical Reports Server (NTRS)

    Egolf, T. Alan; Anderson, Olof L.; Edwards, David E.; Landgrebe, Anton J.

    1988-01-01

    A user's manual for the computer program developed for the prediction of propeller-nacelle aerodynamic performance reported in, An Analysis for High Speed Propeller-Nacelle Aerodynamic Performance Prediction: Volume 1 -- Theory and Application, is presented. The manual describes the computer program mode of operation requirements, input structure, input data requirements and the program output. In addition, it provides the user with documentation of the internal program structure and the software used in the computer program as it relates to the theory presented in Volume 1. Sample input data setups are provided along with selected printout of the program output for one of the sample setups.

  10. Subsonic-to-Hypersonic Aerodynamic Characteristics for a Winged, Circular-Body, Single-Stage-to-Orbit Spacecraft Configuration

    NASA Technical Reports Server (NTRS)

    Phillips, W. P.; Engelund, W. C.

    1995-01-01

    Experimental aerodynamic characteristics were obtained for a generic, winged, circular-body, single-stage-to-orbit spacecraft configuration. The baseline configuration was longitudinally stable and trimmable at almost all Mach numbers from 0.15 to 10.0--with the exception occurring at low supersonic speeds. Landing speed and subsonic-to-hypersonic longitudinal stability and control appear to be within design guidelines. Lateral-directional instabilities found over the entire speed range, however, create a problem area for this configuration. Longitudinal aerodynamic predictions made utilizing the Aerodynamic Preliminary Analysis System (APAS) were in qualitative, often quantitative agreement with experimental values.

  11. Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight.

    PubMed

    Dyke, Gareth; de Kat, Roeland; Palmer, Colin; van der Kindere, Jacques; Naish, Darren; Ganapathisubramani, Bharathram

    2013-01-01

    Understanding the aerodynamic performance of feathered, non-avialan dinosaurs is critical to reconstructing the evolution of bird flight. Here we show that the Early Cretaceous five-winged paravian Microraptor is most stable when gliding at high-lift coefficients (low lift/drag ratios). Wind tunnel experiments and flight simulations show that sustaining a high-lift coefficient at the expense of high drag would have been the most efficient strategy for Microraptor when gliding from, and between, low elevations. Analyses also demonstrate that anatomically plausible changes in wing configuration and leg position would have made little difference to aerodynamic performance. Significant to the evolution of flight, we show that Microraptor did not require a sophisticated, 'modern' wing morphology to undertake effective glides. This is congruent with the fossil record and also with the hypothesis that symmetric 'flight' feathers first evolved in dinosaurs for non-aerodynamic functions, later being adapted to form lifting surfaces.

  12. Low-speed aerodynamic characteristics of a 13 percent thick medium speed airfoil designed for general aviation applications

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Beasley, W. D.

    1979-01-01

    Wind tunnel tests were conducted to determine the low speed, two dimensional aerodynamic characteristics of a 13percent thick medium speed airfoil designed for general aviation applications. The results were compared with data for the 13 percent thick low speed airfoil. The tests were conducted over a Mach number range from 0.10 to 0.32, a chord Reynolds number range from 2.0 x 10 to the 6th power to 12.0 x 10 to the 6th power, and an angle of attack frange from about -8 deg to 10 deg. The objective of retaining good high-lift low speed characteristics for an airfoil designed to have good medium speed cruise performance was achieved.

  13. Aerodynamic and performance characterization of supersonic retropropulsion for application to planetary entry and descent

    NASA Astrophysics Data System (ADS)

    Korzun, Ashley M.

    shock layer of a blunt body in supersonic flow. Although numerous wind tunnel tests of relevance to SRP have been conducted, the scope of the work is limited in the freestream conditions and composition, retropropulsion conditions and composition, and configurations and geometries explored. The SRP aerodynamic - propulsive interaction alters the aerodynamic characteristics of the vehicle, and models must be developed that accurately represent the impact of SRP on system mass and performance. Work within this thesis has defined and advanced the state of the art for supersonic retropropulsion. This has been achieved through the application of systems analysis, computational analysis, and analytical methods. The contributions of this thesis include a detailed performance analysis and exploration of the design space specific to supersonic retropropulsion, establishment of the relationship between vehicle performance and the aerodynamic - propulsive interaction, and an assessment of the required fidelity and computational cost in simulating supersonic retropropulsion flowfields, with emphasis on the effort required to develop aerodynamic databases for conceptual design.

  14. Theoretical aerodynamic characteristics of a family of slender wing-tail-body combinations

    NASA Technical Reports Server (NTRS)

    Lomax, Harvard; Byrd, Paul F

    1951-01-01

    The aerodynamic characteristics of an airplane configuration composed of a swept-back, nearly constant chord wing and a triangular tail mounted on a cylindrical body are presented. The analysis is based on the assumption that the free-stream Mach number is near unity or that the configuration is slender. The calculations for the tail are made on the assumption that the vortex system trailing back from the wing is either a sheet lying entirely in the plane of the flat tail surface or has completely "rolled up" into two point vortices that lie either in, above, or below the plane of the tail surface.

  15. Prediction of Aerodynamic Characteristics of Fighter Wings at High Angles of Attack.

    DTIC Science & Technology

    1984-03-01

    method coupled with iterative routines for wake location, viscous effects and vortex flows. Applications of the techniques to a number of...AD-A145 1@7 PREDICTION OF AERODYNAMIC CHARACTERISTICS OF FIGHTER i/2 WIINGS AT HIGH ANGLES OF ATTACK(U) ANALYTICAL METHODS INC REDMOND WA B MASKEW ET...ATTACK I B. !4askew T.S. Vaidyanathan J.K. Nathman F.A. Dvorak Analytical Methods , Inc. 2047 - 152nd Avenue N.E. Redmond, Washington 98052 CONTRACT

  16. Supersonic aerodynamic characteristics of some reentry concepts for angles of attack to 90 deg

    NASA Astrophysics Data System (ADS)

    Spearman, M. L.

    1985-11-01

    Past studies of reentry vehicles tested to high angles of attack (up to 90 deg) in the Mach number range from 2 to 4.8 are reviewed. Two basic planforms are considered: highly-swept deltas and circular. The delta concepts include variations in cross section (and thus volume) and in camber distribution. The effectiveness of various types of aerodynamic control devices is also included. The purpose of the paper is to examine the characteristics of the vehicles with a view toward the potential usefulness of such concepts in a flight regime that would include reentry from space into the atmosphere followed by a transition to sustained atmospheric flight.

  17. The characteristics of the ground vortex and its effect on the aerodynamics of the STOL configuration

    NASA Technical Reports Server (NTRS)

    Stewart, Vearle R.

    1988-01-01

    The interaction of the free stream velocity on the wall jet formed by the impingement of deflected engine thrust results in a rolled up vortex which exerts sizable forces on a short takeoff (STOL) airplane configuration. Some data suggest that the boundary layer under the free stream ahead of the configuration may be important in determining the extent of the travel of the wall jet into the oncoming stream. Here, early studies of the ground vortex are examined, and those results are compared to some later data obtained with moving a model over a fixed ground board. The effect of the ground vortex on the aerodynamic characteristics are discussed.

  18. Aerodynamic Performance Predictions of Single and Twin Jet Afterbodies

    NASA Technical Reports Server (NTRS)

    Carlson, John R.; Pao, S. Paul; Abdol-Hamid, Khaled S.; Jones, William T.

    1995-01-01

    The multiblock three-dimensional Navier-Stokes method PAB3D was utilized by the Component Integration Branch (formerly Propulsion Aerodynamics Branch) at the NASA-Langley Research Center in an international study sponsored by AGARD Working Group #17 for the assessment of the state-of-the-art of propulsion-airframe integration testing techniques and CFD prediction technologies. Three test geometries from ONERA involving fundamental flow physics and four geometries from NASA-LaRC involving realistic flow interactions of wing, body, tail, and jet plumes were chosen by the Working Group. An overview of results on four (1 ONERA and 3 LaRC) of the seven test cases is presented. External static pressures, integrated pressure drag and total drag were calculated for the Langley test cases and jet plume velocity profiles and turbulent viscous stresses were calculated for the ONERA test case. Only selected data from these calculations are presented in this paper. The complete data sets calculated by the participants will be presented in an AGARD summary report. Predicted surface static pressures compared favorably with experimental data for the Langley geometries. Predicted afterbody drag compared well with experiment. Predicted nozzle drag was typically low due to over-compression of the flow near the trailing edge. Total drag was typically high. Predicted jet plume quantities on the ONERA case compared generally well with data.

  19. Cylinder wake influence on the tonal noise and aerodynamic characteristics of a NACA0018 airfoil

    NASA Astrophysics Data System (ADS)

    Takagi, Y.; Fujisawa, N.; Nakano, T.; Nashimoto, A.

    2006-11-01

    The influence of cylinder wake on discrete tonal noise and aerodynamic characteristics of a NACA0018 airfoil is studied experimentally in a uniform flow at a moderate Reynolds number. The experiments are carried out by measuring sound pressure levels and spectrum, separation and the reattachment points, pressure distribution, fluid forces, mean-flow and turbulence characteristics around the airfoil with and without the cylinder wake. Present results indicate that the tonal noise from the airfoil is suppressed by the influence of the cylinder wake and the aerodynamic characteristics are improved in comparison with the case without the cylinder wake. These are mainly due to the separation control of boundary layers over the airfoil caused by the wake-induced transition, which is observed by surface flow visualization with liquid- crystal coating. The PIV measurements of the flow field around the airfoil confirm that highly turbulent velocity fluctuation of the cylinder wake induces the transition of the boundary layers and produces an attached boundary layer over the airfoil. Then, the vortex shedding phenomenon near the trailing edge of pressure surface is removed by the influence of the wake and results in the suppression of tonal noise.

  20. Aerodynamic performance of a vibrating piezoelectric fan under varied operational conditions

    NASA Astrophysics Data System (ADS)

    Stafford, J.; Jeffers, N.

    2014-07-01

    This paper experimentally examines the bulk aerodynamic performance of a vibrating fan operating in the first mode of vibration. The influence of operating condition on the local velocity field has also been investigated to understand the flow distribution at the exit region and determine the stalling condition for vibrating fans. Fan motion has been generated and controlled using a piezoelectric ceramic attached to a stainless steel cantilever. The frequency and amplitude at resonance were 109.4 Hz and 12.5 mm, respectively. A test facility has been developed to measure the pressure-flow characteristics of the vibrating fan and simultaneously conduct local velocity field measurements using particle image velocimetry. The results demonstrate the impact of system characteristics on the local velocity field. High momentum regions generated due to the oscillating motion exist with a component direction that is tangent to the blade at maximum displacement. These high velocity zones are significantly affected by increasing impedance while flow reversal is a dominant feature at maximum pressure rise. The findings outlined provide useful information for design of thermal management solutions that may incorporate this air cooling approach.

  1. Effect of vane opening on aerodynamic performance of the ram-rotor test system

    NASA Astrophysics Data System (ADS)

    Han, Ji-ang; Guan, Jian; Zhong, Jingjun; Yuan, Chenguang

    2016-06-01

    In order to research the influence of adjustable vane on the aerodynamic performance of the ram-rotor test system, FLUENT software has been adopted to simulate the flow passage of the ram-rotor test system numerically. The vane opening is controlled by changing the stagger angle of the vane blades. Results show that flow uniformity of vane outlet is influenced by the vane openings, which has an impact on the aerodynamic loss to some extent. Total pressure ratio, adiabatic efficiency and mass flow rate can be regulated by different openings of the vane. Compared with -8° vane opening, top efficiency of the ram-rotor increases by about 13.8% at +6° opening. And total pressure ratio drops by 5.87%. The rising opening increases the relative Mach number at inlet of the ram-rotor and weakens the intensity of the tip clearance leakage, which comes to a decreasing aerodynamic loss.

  2. Dynamic interactions between hypersonic vehicle aerodynamics and propulsion system performance

    NASA Technical Reports Server (NTRS)

    Flandro, G. A.; Roach, R. L.; Buschek, H.

    1992-01-01

    Described here is the development of a flexible simulation model for scramjet hypersonic propulsion systems. The primary goal is determination of sensitivity of the thrust vector and other system parameters to angle of attack changes of the vehicle. Such information is crucial in design and analysis of control system performance for hypersonic vehicles. The code is also intended to be a key element in carrying out dynamic interaction studies involving the influence of vehicle vibrations on propulsion system/control system coupling and flight stability. Simple models are employed to represent the various processes comprising the propulsion system. A method of characteristics (MOC) approach is used to solve the forebody and external nozzle flow fields. This results in a very fast computational algorithm capable of carrying out the vast number of simulation computations needed in guidance, stability, and control studies. The three-dimensional fore- and aft body (nozzle) geometry is characterized by the centerline profiles as represented by a series of coordinate points and body cross-section curvature. The engine module geometry is represented by an adjustable vertical grid to accommodate variations of the field parameters throughout the inlet and combustor. The scramjet inlet is modeled as a two-dimensional supersonic flow containing adjustable sidewall wedges and multiple fuel injection struts. The inlet geometry including the sidewall wedge angles, the number of injection struts, their sweepback relative to the vehicle reference line, and strut cross-section are user selectable. Combustion is currently represented by a Rayleigh line calculation including corrections for variable gas properties; improved models are being developed for this important element of the propulsion flow field. The program generates (1) variation of thrust magnitude and direction with angle of attack, (2) pitching moment and line of action of the thrust vector, (3) pressure and temperature

  3. Large-scale aerodynamic characteristics of airfoils as tested in the variable density wind tunnel

    NASA Technical Reports Server (NTRS)

    Jacobs, Eastman N; Anderson, Raymond F

    1931-01-01

    In order to give the large-scale characteristics of a variety of airfoils in a form which will be of maximum value, both for airplane design and for the study of airfoil characteristics, a collection has been made of the results of airfoil tests made at full-scale values of the reynolds number in the variable density wind tunnel of the National Advisory Committee for Aeronautics. They have been corrected for tunnel wall interference and are presented not only in the conventional form but also in a form which facilitates the comparison of airfoils and from which corrections may be easily made to any aspect ratio. An example showing the method of correcting the results to a desired aspect ratio has been given for the convenience of designers. In addition, the data have been analyzed with a view to finding the variation of the aerodynamic characteristics of airfoils with their thickness and camber.

  4. An Overview of National Transonic Facility Investigations for High Performance Military Aerodynamics (Invited)

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    2001-01-01

    A review of National Transonic Facility (NTF) investigations for high-performance military aerodynamics has been completed. The review spans the entire operational period of the tunnel, and includes configurations ranging from full aircraft to basic research geometries. The intent for this document is to establish a comprehensive summary of these experiments with selected technical results

  5. Air-permeable hole-pattern and nose-droop control improve aerodynamic performance of primary feathers.

    PubMed

    Eder, Heinrich; Fiedler, Wolfgang; Pascoe, Xaver

    2011-01-01

    Primary feathers of soaring land birds have evolved into highly specialized flight feathers characterized by morphological improvements affecting aerodynamic performance. The foremost feathers in the cascade have to bear high lift-loading with a strong bending during soaring flight. A challenge to the study of feather aerodynamics is to understand how the observed low drag and high lift values in the Reynolds (Re) regime from 1.0 to 2.0E4 can be achieved. Computed micro-tomography images show that the feather responds to high lift-loading with an increasing nose-droop and profile-camber. Wind-tunnel tests conducted with the foremost primary feather of a White Stork (Ciconia ciconia) at Re = 1.8E4 indicated a surprisingly high maximum lift coefficient of 1.5 and a glide ratio of nearly 10. We present evidence that this is due to morphologic characteristics formed by the cristae dorsales as well as air-permeable arrays along the rhachis. Measurements of lift and drag forces with open and closed pores confirmed the efficiency of this mechanism. Porous structures facilitate a blow out, comparable to technical blow-hole turbulators for sailplanes and low speed turbine-blades. From our findings, we conclude that the mechanism has evolved in order to affect the boundary layer and to reduce aerodynamic drag of the feather.

  6. Effects of perforation number of blade on aerodynamic performance of dual-rotor small axial flow fans

    NASA Astrophysics Data System (ADS)

    Hu, Yongjun; Wang, Yanping; Li, Guoqi; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

    2015-04-01

    Compared with single rotor small axial flow fans, dual-rotor small axial flow fans is better regarding the static characteristics. But the aerodynamic noise of dual-rotor small axial flow fans is worse than that of single rotor small axial flow fans. In order to improve aerodynamic noise of dual-rotor small axial flow fans, the pre-stage blades with different perforation numbers are designed in this research. The RANS equations and the standard k-ɛ turbulence model as well as the FW-H noise model are used to simulate the flow field within the fan. Then, the aerodynamic performance of the fans with different perforation number is compared and analyzed. The results show that: (1) Compared to the prototype fan, the noise of fans with perforation blades is reduced. Additionally, the noise of the fans decreases with the increase of the number of perforations. (2) The vorticity value in the trailing edge of the pre-stage blades of perforated fans is reduced. It is found that the vorticity value in the trailing edge of the pre-stage blades decreases with the increase of the number of perforations. (3) Compared to the prototype fan, the total pressure rising and efficiency of the fans with perforation blades drop slightly.

  7. Comparing Aerodynamic Efficiency in Birds and Bats Suggests Better Flight Performance in Birds

    PubMed Central

    Muijres, Florian T.; Johansson, L. Christoffer; Bowlin, Melissa S.; Winter, York; Hedenström, Anders

    2012-01-01

    Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate longer distances

  8. Static aerodynamic characteristics of a single-stage-to-orbit vehicle with low planform loading at Mach numbers from 0.3 to 4.63

    NASA Technical Reports Server (NTRS)

    Freeman, D. C., Jr.; Fournier, R. H.

    1977-01-01

    Transonic pressure and wind tunnel studies were performed to determine the longitudinal and lateral aerodynamic characteristics of a single-stage-to-orbit vehicle which utilizes an all metallic, hot structure, thermal protection system resulting in low planform loading. The model was tested over a Mach number range from 0.3 to 4.63 for angles of attack from -4 deg to 32 deg at both 0 deg and 5 deg sideslip.

  9. Aerodynamic characteristics and pressure distributions for an executive-jet baseline airfoil section

    NASA Technical Reports Server (NTRS)

    Allison, Dennis O.; Mineck, Raymond E.

    1993-01-01

    A wind tunnel test of an executive-jet baseline airfoil model was conducted in the adaptive-wall test section of the NASA Langley 0.3-Meter Transonic Cryogenic Tunnel. The primary goal of the test was to measure airfoil aerodynamic characteristics over a wide range of flow conditions that encompass two design points. The two design Mach numbers were 0.654 and 0.735 with corresponding Reynolds numbers of 4.5 x 10(exp 6) and 8.9 x 10(exp 6) based on chord, respectively, and normal-force coefficients of 0.98 and 0.51, respectively. The tests were conducted over a Mach number range from 0.250 to 0.780 and a chord Reynolds number range from 3 x 10(exp 6) to 18 x 10(exp 6). The angle of attack was varied from -2 deg to a maximum below 10 deg with one exception in which the maximum was 14 deg for a Mach number of 0.250 at a chord Reynolds number of 4.5 x 10(exp 6). Boundary-layer transition was fixed at 5 percent of chord on both the upper and lower surfaces of the model for most of the test. The adaptive-wall test section had flexible top and bottom walls and rigid sidewalls. Wall interference was minimized by the movement of the adaptive walls, and the airfoil aerodynamic characteristics were corrected for any residual top and bottom wall interference.

  10. Calculation of static longitudinal aerodynamic characteristics of STOL aircraft with upper surface blown flaps

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Perkin, S. C., Jr.; Goodwin, F. K.; Spangler, S. B.

    1975-01-01

    An existing prediction method developed for EBF aircraft configurations was applied to USB configurations to determine its potential utility in predicting USB aerodynamic characteristics. An existing wing-flap vortex-lattice computer program was modified to handle multiple spanwise flap segments at different flap angles. A potential flow turbofan wake model developed for circular cross-section jets was used to model a rectangular cross-section jet wake by placing a number of circular jets side by side. The calculation procedure was evaluated by comparison of measured and predicted aerodynamic characteristics on a variety of USB configurations. The method is limited to the case where the flow and geometry of the configuration are symmetric about a vertical plane containing the wing root chord. Comparison of predicted and measured lift and pitching moment coefficients were made on swept wings with one and two engines per wing panel, various flap deflection angles, and a range of thrust coefficients. The results indicate satisfactory prediction of lift for flap deflections up to 55 and thrust coefficients less than 2. The applicability of the prediction procedure to USB configurations is evaluated, and specific recommendations for improvements are discussed.

  11. Semi-Empirical Prediction of Aircraft Low-Speed Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Olson, Erik D.

    2015-01-01

    This paper lays out a comprehensive methodology for computing a low-speed, high-lift polar, without requiring additional details about the aircraft design beyond what is typically available at the conceptual design stage. Introducing low-order, physics-based aerodynamic analyses allows the methodology to be more applicable to unconventional aircraft concepts than traditional, fully-empirical methods. The methodology uses empirical relationships for flap lift effectiveness, chord extension, drag-coefficient increment and maximum lift coefficient of various types of flap systems as a function of flap deflection, and combines these increments with the characteristics of the unflapped airfoils. Once the aerodynamic characteristics of the flapped sections are known, a vortex-lattice analysis calculates the three-dimensional lift, drag and moment coefficients of the whole aircraft configuration. This paper details the results of two validation cases: a supercritical airfoil model with several types of flaps; and a 12-foot, full-span aircraft model with slats and double-slotted flaps.

  12. Aerodynamic characteristics of the orbital reentry vehicle experimental probe fins in a supersonic flow

    NASA Astrophysics Data System (ADS)

    Watanabe, Mitsunori; Sekine, Hideo; Tate, Atsushi; Noda, Junichi

    1994-04-01

    The aerodynamic characteristics of probe fins with a sweep angle of 60 deg, which are equipped on the Orbital Reentry Experiment (OREX) vehicle to measure the surrounding ionized gas temperature and electron number density distributions in the high temperature communication black out regions, have been measured in the supersonic wind tunnel of the National Aerospace Laboratory and compared with those of the fins of 0 deg sweep angles. Since the probes are to be embedded in the boundary layer where the local Mach number is less than 2.5 over the OREX surface at a hypersonic flight speed, the aerodynamic characteristics in supersonic regions are needed to estimate the rolling moments of fins caused by the error of the installation angles. The lift coefficient slope of the probe fins decreases as the Mach number increases, being less than the values for the 0 deg sweep fins. The drag coefficient depends highly on the sweep angle of the fins in Mach number regions less than 2.5.

  13. Hypersonic aerodynamic characteristics of an all-body research aircraft configuration

    NASA Technical Reports Server (NTRS)

    Clark, L. E.

    1973-01-01

    An experimental investigation was conducted at Mach 6 to determine the hypersonic aerodynamic characteristics of an all-body, delta-planform, hypersonic research aircraft (HYFAC configuration). The aerodynamic characteristics were obtained at Reynolds numbers based on model length of 2.84 million and 10.5 million and over an angle-of-attack range from minus 4 deg to 20 deg. The experimental results show that the HYFAC configuration is longitudinally stable and can be trimmed over the range of test conditions. The configuration had a small degree of directional stability over the angle-of-attack range and positive effective dihedral at angles of attack greater than 2 deg. Addition of canards caused a decrease in longitudinal stability and an increase in directional stability. Oil-flow studies revealed extensive areas of separated and vortex flow on the fuselage lee surface. A limited comparison of wind-tunnel data with several hypersonic approximations indicated that, except for the directional stability, the tangent-cone method gave adequate agreement at control settings between 5 deg and minus 5 deg and positive lift coefficient. A limited comparison indicated that the HYFAC configuration had greater longitudinal stability than an elliptical-cross-section configuration, but a lower maximum lift-drag ratio.

  14. Numerical and Experimental Study on Aerodynamic Characteristics of Basic Airfoils at Low Reynolds Numbers

    NASA Astrophysics Data System (ADS)

    Hirata, Katsuya; Kawakita, Masatoshi; Iijima, Takayoshi; Koga, Mitsuhiro; Kihira, Mitsuhiko; Funaki, Jiro

    The aerodynamic characteristics of airfoils have been researched in higher Reynolds-number ranges more than 106, in a historic context closely related with the developments of airplanes and fluid machineries in the last century. However, our knowledge is not enough at low and middle Reynolds-number ranges. So, in the present study, we investigate such basic airfoils as a NACA0015, a flat plate and the flat plates with modified fore-face and after-face geometries at Reynolds number Re < 1.0×105, using two- and three-dimensional computations together with wind-tunnel and water-tank experiments. As a result, we have revealed the effect of the Reynolds number Re upon the minimum drag coefficient CDmin. Besides, we have shown the effects of attack angle α upon various aerodynamic characteristics such as the lift coefficient CL, the drag coefficient CD and the lift-to-drag ratio CL/CD at Re = 1.0×102, discussing those effects on the basis of both near-flow-field information and surface-pressure profiles. Such results suggest the importance of sharp leading edges, which implies the possibility of an inversed NACA0015. Furthermore, concerning the flat-plate airfoil, we investigate the influences of fore-face and after-face geometries upon such effects.

  15. Effect of symmetrical vortex shedding on the longitudinal aerodynamic characteristics of wing-body-tail combinations

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Nielsen, J. N.

    1975-01-01

    An engineering prediction method for determining the longitudinal aerodynamic characteristics of wing-body-tail combinations is developed. The method includes the effects of nonlinear aerodynamics of components and the interference between components. Nonlinearities associated with symmetrical vortex shedding from the nose of the body are considered as well as the nonlinearities associated with the separation vortices from the leading edges and side edges of the lifting surfaces. The wing and tail characteristics are calculated using lifting surface theories which include effects of incidence, camber, twist, and induced velocities from external sources of disturbance such as bodies and vortices. The lifting surface theories calculate the distribution of leading edge and side edge suction which is converted to vortex lift using the Polhamus suction analogy. Correlation curves are developed to determine the fraction of the theoretical suction force which is converted into vortex lift. The prediction method is compared with experimental data on a variety of aircraft configurations to assess the accuracy and limitations of the method.

  16. Predicted Aerodynamic Characteristics of a NACA 0015 Airfoil Having a 25% Integral-Type Trailing Edge Flap

    NASA Technical Reports Server (NTRS)

    Hassan, Ahmed

    1999-01-01

    Using the two-dimensional ARC2D Navier-Stokes flow solver analyses were conducted to predict the sectional aerodynamic characteristics of the flapped NACA-0015 airfoil section. To facilitate the analyses and the generation of the computational grids, the airfoil with the deflected trailing edge flap was treated as a single element airfoil with no allowance for a gap between the flap's leading edge and the base of the forward portion of the airfoil. Generation of the O-type computational grids was accomplished using the HYGRID hyperbolic grid generation program. Results were obtained for a wide range of Mach numbers, angles of attack and flap deflections. The predicted sectional lift, drag and pitching moment values for the airfoil were then cast in tabular format (C81) to be used in lifting-line helicopter rotor aerodynamic performance calculations. Similar were also generated for the flap. Mathematical expressions providing the variation of the sectional lift and pitching moment coefficients for the airfoil and for the flap as a function of flap chord length and flap deflection angle were derived within the context of thin airfoil theory. The airfoil's sectional drag coefficient were derived using the ARC2D drag predictions for equivalent two dimensional flow conditions.

  17. Wind-tunnel studies of the effects of simulated damage on the aerodynamic characteristics of airplanes and missiles

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.

    1979-01-01

    In order to assess the effects on static aerodynamic characteristics of battle damage to an aircraft or missile, wind tunnel studies were performed on models from which all or parts of the wing or horizontal or vertical tail had been removed. The effects of damage on the lift, longitudinal stability, lateral stability and directional stability of a swept-wing fighter are presented, along with the effects of wing removal on the control requirements of a delta-wing fighter. Results indicate that the loss of a major part of the vertical tail will probably result in the loss of the aircraft at any speed, while the loss of major parts of the horizontal tail generally results in catastrophic instability at subsonic speeds but, at low supersonic speeds, may allow the aircraft to return to friendly territory before pilot ejection. Major damage to the wing may be sustained without the loss of aircraft or pilot. The loss of some of the aerodynamic surfaces of cruise or surface-to-air missiles may result in catastrophic instability or may permit a ballistic trajectory to be maintained, depending upon the location of the lost surface with respect to the center of gravity of the missile.

  18. Experimental and theoretical study of aerodynamic characteristics of some lifting bodies at angles of attack from -10 degrees to 53 degrees at Mach numbers from 2.30 to 4.62

    NASA Technical Reports Server (NTRS)

    Spearman, M. Leroy; Torres, Abel O.

    1994-01-01

    Lifting bodies are of interest for possible use as space transportation vehicles because they have the volume required for significant payloads and the aerodynamic capability to negotiate the transition from high angles of attack to lower angles of attack (for cruise flight) and thus safely reenter the atmosphere and perform conventional horizontal landings. Results are presented for an experimental and theoretical study of the aerodynamic characteristics at supersonic speeds for a series of lifting bodies with 75 deg delta planforms, rounded noses, and various upper and lower surface cambers. The camber shapes varied in thickness and in maximum thickness location, and hence in body volume. The experimental results were obtained in the Langley Unitary Plan Wind Tunnel for both the longitudinal and the lateral aerodynamic characteristics. Selected experimental results are compared with calculated results obtained through the use of the Hypersonic Arbitrary-Body Aerodynamic Computer Program.

  19. Effect of wing design on the longitudinal aerodynamic characteristics of a wing-body model at subsonic speeds

    NASA Technical Reports Server (NTRS)

    Henderson, W. P.; Huffman, J. K.

    1972-01-01

    An investigation has been conducted to determine the effects of wing camber and twist on the longitudinal aerodynamic characteristics of a wingbody configuration. Three wings were used each having the same planform (aspect ratio of 2.5 and leading-edge sweep angle of 44 deg.) but differing in amounts of camber and twist (wing design lift coefficient). The wing design lift coefficients were 0, 0.35, and 0.70. The investigation was conducted over a Mach number range from 0.20 to 0.70 at angles of attack up to about 22 deg. The effect of wing strakes on the aerodynamic characteristics of the cambered wings was also studied. A comparison of the experimentally determined aerodynamic characteristics with theoretical estimates is also included.

  20. Effect of the Surface Condition of a Wing on the Aerodynamic Characteristics of an Airplane

    NASA Technical Reports Server (NTRS)

    Defrance, S J

    1934-01-01

    In order to determine the effect of the surface conditions of a wing on the aerodynamic characteristics of an airplane, tests were conducted in the N.A.C.A. full-scale wind tunnel on the Fairchild F-22 airplane first with normal commercial finish of wing surface and later with the same wing polished. Comparison of the characteristics of the airplane with the two surface conditions shows that the polish caused a negligible change in the lift curve, but reduced the minimum drag coefficient by 0.001. This reduction in drag if applied to an airplane with a given speed of 200 miles per hour and a minimum drag coefficient of 0.025 would increase the speed only 2.9 miles per hour, but if the speed remained the same, the power would be reduced 4 percent.

  1. Rotary-wing aerodynamics. Volume 2: Performance prediction of helicopters

    NASA Technical Reports Server (NTRS)

    Keys, C. N.; Stephniewski, W. Z. (Editor)

    1979-01-01

    Application of theories, as well as, special methods of procedures applicable to performance prediction are illustrated first, on an example of the conventional helicopter and then, winged and tandem configurations. Performance prediction of conventional helicopters in hover and vertical ascent are investigated. Various approaches to performance prediction in forward translation are presented. Performance problems are discussed only this time, a wing is added to the baseline configuration, and both aircraft are compared with respect to their performance. This comparison is extended to a tandem. Appendices on methods for estimating performance guarantees and growth of aircraft concludes this volume.

  2. Effect of leading-edge vortex flaps on aerodynamic performance of delta wings

    NASA Technical Reports Server (NTRS)

    Reddy, C. S.

    1981-01-01

    The effect of leading-edge vortex flaps on the aerodynamic characteristics of highly swept-back wings is analytically investigated, using the free vortex sheet method. The method, based on a three-dimensional inviscid flow model, is an advanced panel type employing quadratic doublet distributions to represent the wing surface, rolled-up vortex sheet and wake and is capable of computing forces, moments and surface pressures.

  3. Influence of the postion of crew members on aerodynamics performance of two-man bobsleigh.

    PubMed

    Dabnichki, Peter; Avital, Eldad

    2006-01-01

    Bobsleigh aerodynamics has long been recognised as one of the crucial performance factors. Although the published research in the area is very limited, it is well known that the leading nations in the sport devote significant resources in research and development of sleds' aerodynamics. However, the rules and regulations pose strict design constraints on the shape modifications aiming at aerodynamics improvements. The reason for that is two-fold: (i) safety of the athletes and (ii) reduction of equipment impact on competition outcome. One particular area that has not been looked at and falls outside the current rules and regulations is the influence of the crew positioning and internal modifications on the aerodynamic performance. The current study presents results on numerical simulation of the flow in the cavity underpinned with some experimental measurements including flow visualisation of the air circulation around the bobsleigh. A simplified computational model was developed to assess the trends and its results validated by windtunnel tests. The results show that crew members influence the drag level significantly and suggest that purely internal modifications can be introduced to reduce the overall resistance drag.

  4. Gap and stagger effects on the aerodynamic performance and the wake behind a biplane with endplates

    NASA Astrophysics Data System (ADS)

    Kang, Hantae

    Modern flow diagnostics applied to a very old aerodynamic problem has produced a number of intriguing new results and new insight into previous results. The aerodynamic performance and associated flow physics of the biplane with endplates as a function of variation in gap and stagger were analytically and experimentally investigated. A combination of vortex lattice method, integrated force measurement, streamwise PIV, and Trefftz plane Stereo PIV were used to better understand the flowfield around the biplane with endplates. This study was performed to determine the configuration with the optimal aerodynamic performance and to understand the fluid mechanics behind optimal and suboptimal performance of the configuration. The Vortex Lattice code (AVL) shows that the gap and stagger have the most dramatic effects out of the six parameters studied: gap, stagger, dihedral, decalage, sweep and overhang. The force balance measurements with fourteen biplane configurations of different gaps and staggers show that as gap and stagger increase, the lift efficiency also increases at all angles of attack tested at both Re 60,000 and 120,000. Using the force balance data, a generalized empirical method for the prediction of lift coefficient as a function of gap, stagger and angle of attack has been determined and validated when combined with existing relations for CL--α adjustments for AR and taper effects. The resulting empirical approach allows for a rapid determination of CL for a biplane having different gap, stagger, AR and taper without the need for a complete flowfield analysis. Two Dimensional PIV results show a distinctive pattern in the downwash angle for the different gap and stagger configurations tested. The downwash angle increases with increasing gap and stagger. It is also evident that the change in downwash angle is directly proportional to the change in lift coefficient as would be expected. Increasing gap spacing increases the downwash angle as well. Based on

  5. Aerodynamic Design Criteria for Class 8 Heavy Vehicles Trailer Base Devices to Attain Optimum Performance

    SciTech Connect

    Salari, K; Ortega, J

    2010-12-13

    Lawrence Livermore National Laboratory (LLNL) as part of its Department of Energy (DOE), Energy Efficiency and Renewable Energy (EERE), and Vehicle Technologies Program (VTP) effort has investigated class 8 tractor-trailer aerodynamics for many years. This effort has identified many drag producing flow structures around the heavy vehicles and also has designed and tested many new active and passive drag reduction techniques and concepts for significant on the road fuel economy improvements. As part of this effort a database of experimental, computational, and conceptual design for aerodynamic drag reduction devices has been established. The objective of this report is to provide design guidance for trailer base devices to improve their aerodynamic performance. These devices are commonly referred to as boattails, base flaps, tail devices, and etc. The information provided here is based on past research and our most recent full-scale experimental investigations in collaboration with Navistar Inc. Additional supporting data from LLNL/Navistar wind tunnel, track test, and on the road test will be published soon. The trailer base devices can be identified by 4 flat panels that are attached to the rear edges of the trailer base to form a closed cavity. These devices have been engineered in many different forms such as, inflatable and non-inflatable, 3 and 4-sided, closed and open cavity, and etc. The following is an in-depth discussion with some recommendations, based on existing data and current research activities, of changes that could be made to these devices to improve their aerodynamic performance. There are 6 primary factors that could influence the aerodynamic performance of trailer base devices: (1) Deflection angle; (2) Boattail length; (3) Sealing of edges and corners; (4) 3 versus 4-sided, Position of the 4th plate; (5) Boattail vertical extension, Skirt - boattail transition; and (6) Closed versus open cavity.

  6. Performance and Design Investigation of Heavy Lift Tiltrotor with Aerodynamic Interference Effects

    NASA Technical Reports Server (NTRS)

    Yeo, Yyeonsoo; Johnson, Wayne

    2007-01-01

    The aerodynamic interference effects on tiltrotor performance in cruise are investigated using comprehensive calculations, to better understand the physics and to quantify the effects on the aircraft design. Performance calculations were conducted for 146,600-lb conventional and quad tiltrotors, which are to cruise at 300 knots at 4000 ft/95 deg F condition. A parametric study was conducted to understand the effects of design parameters on the performance of the aircraft. Aerodynamic interference improves the aircraft lift-to-drag ratio of the baseline conventional tiltrotor. However, interference degrades the aircraft performance of the baseline quad tiltrotor, due mostly to the unfavorable effects from the front wing to the rear wing. A reduction of rotor tip speed increased the aircraft lift-to-drag ratio the most among the design parameters investigated.

  7. Novel method and apparatus for controlling aerodynamic performance of an operating axial-flow fluid machine

    SciTech Connect

    Langebrake, C.O.

    1980-07-11

    This invention is an improved method and arrangement for controlling the aerodynamic performance of an axial-flow fluid machine during its operation. In one form of the invention, the improved control is effected by providing the machine with at least one annular row of tandem airfoils, each consisting of a trailing vane and a fixed leading vane. The trailing vane and leading vane of the typical airfoil cooperatively define a gap whose width affects the boundary-layer flow over the airfoil and thus the gas-exist angle of the mainstream flow leaving the airfoil. The trailing vanes are affixed to a ring which is mounted for independent, arcuate movement about the axis of rotor rotation, so as to translate the trailing vanes circumferentially to alter the widths of their associated gaps. External means are provided for adjusting the position of the ring during operation of the machine in order to vary the gas-exist angles for the row of tandem airfoils and thereby control selected operating characteristics of the machine, such as suction volume or compression ratio.

  8. Wind tunnel investigation of aerodynamic and tail buffet characteristics of leading-edge extension modifications to the F/A-18

    NASA Technical Reports Server (NTRS)

    Shah, Gautam H.

    1991-01-01

    The impact of leading-edge extension (LEX) modifications on aerodynamic and vertical tail buffet characteristics of a 16-percent scale F/A-18 model has been investigated in the NASA Langley 30-foot by 60-foot tunnel. Modifications under consideration include variations in LEX chord and span, addition of upper surface fences, and removal of the LEX. Both buffeting and high-angle-of-attack aerodynamics are found to be strongly dependent upon the LEX geometry, which directly influences the strength, position, and breakdown characteristics of the vortex flow field. Concepts aimed at influencing the development of vortical flow field are considered to have much greater potential in design application than those geared toward altering already established flow fields. It is recommended that configuration effects on structural and aerodynamic characteristics be evaluated in parallel, so that trade-off studies can be conducted to ensure adequate structural fatigue life and desired high-angle-of-attack stability and control characteristics in the design of future high performance aircraft.

  9. Aerodynamic Characteristics of Three Deep-Stepped Planing-Tail Flying-Boat Hulls

    NASA Technical Reports Server (NTRS)

    Riebe, John M.; Naeseth, Rodger L.

    1947-01-01

    An investigation was made in the Langley 300 MPH 7- by 10-foot tunnel to determine the aerodynamic characteristics of three deep-stepped planing-tail flying-boat hulls differing only in the amount of step fairing. The hulls were derived by increasing the unfaired step depth of a planing-tail hull of a previous aerodynamic investigation to a depth about 92 percent of the hull beam. Tests were also made on a transverse-stepped hull with an extended afterbody for the purpose of comparison and in order to extend and verify the results of a previous investigation. The investigation indicated that the extended afterbody hull had a minimum drag coefficient about the same as a conventional hull, 0.0066, and an angle-of-attack range for minimum drag coefficient of 0.0057 which was 14 percent less than the transverse stepped hull with extended afterbody; the hulls with step fairing had up to 44 percent less minimum drag coefficient than the transverse-stepped hull, or slightly more drag than a streamlined body having approximately the same length and volume. Longitudinal and lateral instability varied little with step fairing and was about the same as a conventional hull.

  10. Experimental and theoretical aerodynamic characteristics of a high-lift semispan wing model

    NASA Technical Reports Server (NTRS)

    Applin, Zachary T.; Gentry, Garl L., Jr.

    1990-01-01

    Experimental and theoretical aerodynamic characteristics were compared for a high-lift, semispan wing configuration that incorporated a slightly modified version of the NASA Advanced Laminar Flow Control airfoil section. The experimental investigation was conducted in the Langley 14- by 22-Foot Subsonic Tunnel at chord Reynolds numbers of 2.36 and 3.33 million. A two-dimensional airfoil code and a three-dimensional panel code were used to obtain aerodynamic predictions. Two-dimensional data were corrected for three-dimensional effects. Comparisons between predicted and measured values were made for the cruise configuration and for various high-lift configurations. Both codes predicted lift and pitching moment coefficients that agreed well with experiment for the cruise configuration. These parameters were overpredicted for all high-lift configurations. Drag coefficient was underpredicted for all cases. Corrected two-dimensional pressure distributions typically agreed well with experiment, while the panel code overpredicted the leading-edge suction peak on the wing. One important feature missing from both of these codes was a capability for separated flow analysis. The major cause of disparity between the measured data and predictions presented herein was attributed to separated flow conditions.

  11. Aerodynamics and performance verifications of test methods for laboratory fume cupboards.

    PubMed

    Tseng, Li-Ching; Huang, Rong Fung; Chen, Chih-Chieh; Chang, Cheng-Ping

    2007-03-01

    The laser-light-sheet-assisted smoke flow visualization technique is performed on a full-size, transparent, commercial grade chemical fume cupboard to diagnose the flow characteristics and to verify the validity of several current containment test methods. The visualized flow patterns identify the recirculation areas that would inevitably exist in the conventional fume cupboards because of the fundamental configurations and structures. The large-scale vortex structures exist around the side walls, the doorsill of the cupboard and in the vicinity of the near-wake region of the manikin. The identified recirculation areas are taken as the 'dangerous' regions where the risk of turbulent dispersion of contaminants may be high. Several existing tracer gas containment test methods (BS 7258:1994, prEN 14175-3:2003 and ANSI/ASHRAE 110:1995) are conducted to verify the effectiveness of these methods in detecting the contaminant leakage. By comparing the results of the flow visualization and the tracer gas tests, it is found that the local recirculation regions are more prone to contaminant leakage because of the complex interaction between the shear layers and the smoke movement through the mechanism of turbulent dispersion. From the point of view of aerodynamics, the present study verifies that the methodology of the prEN 14175-3:2003 protocol can produce more reliable and consistent results because it is based on the region-by-region measurement and encompasses the most area of the entire recirculation zone of the cupboard. A modified test method combined with the region-by-region approach at the presence of the manikin shows substantially different results of the containment. A better performance test method which can describe an operator's exposure and the correlation between flow characteristics and the contaminant leakage properties is therefore suggested.

  12. Numerical investigation of the aerodynamic and structural characteristics of a corrugated wing

    NASA Astrophysics Data System (ADS)

    Hord, Kyle

    Previous experimental studies on static, bio-inspired corrugated wings have shown that they produce favorable aerodynamic properties such as delayed stall compared to streamlined wings and flat plates at high Reynolds numbers (Re ≥ 4x104). The majority of studies have been carried out with scaled models of dragonfly forewings from the Aeshna Cyanea in either wind tunnels or water channels. In this thesis, the aerodynamics of a corrugated airfoil was studied using computational fluid dynamics methods at a low Reynolds number of 1000. Structural analysis was also performed using the commercial software SolidWorks 2009. The flow field is described by solving the incompressible Navier-Stokes equations on an overlapping grid using the pressure-Poisson method. The equations are discretized in space with second-order accurate central differences. Time integration is achieved through the second-order Crank-Nicolson implicit method. The complex vortex structures that form in the corrugated airfoil valleys and around the corrugated airfoil are studied in detail. Comparisons are made with experimental measurements from corrugated wings and also with simulations of a flat plate. Contrary to the studies at high Reynolds numbers, our study shows that at low Reynolds numbers the wing corrugation does not provide any aerodynamic benefit compared to a smoothed flat plate. Instead, the corrugated profile generates more pressure drag which is only partially offset by the reduction of friction drag, leading to more total drag than the flat plate. Structural analysis shows that the wing corrugation can increase the resistance to bending moments on the wing structure. A smoothed structure has to be three times thicker to provide the same stiffness. It was concluded the corrugated wing has the structural benefit to provide the same resistance to bending moments with a much reduced weight.

  13. The effect of winglets on the static aerodynamic stability characteristics of a representative second generation jet transport model

    NASA Technical Reports Server (NTRS)

    Jacobs, P. F.; Flechner, S. G.

    1976-01-01

    A baseline wing and a version of the same wing fitted with winglets were tested. The longitudinal aerodynamic characteristics were determined through an angle-of-attack range from -1 deg to 10 deg at an angle of sideslip of 0 deg for Mach numbers of 0.750, 0.800, and 0.825. The lateral aerodynamic characteristics were determined through the same angle-of-attack range at fixed sideslip angles of 2.5 deg and 5 deg. Both configurations were investigated at Reynolds numbers of 13,000,000, per meter (4,000,000 per foot) and approximately 20,000,000 per meter (6,000,000 per foot). The winglet configuration showed slight increases over the baseline wing in static longitudinal and lateral aerodynamic stability throughout the test Mach number range for a model design lift coefficient of 0.53. Reynolds number variation had very little effect on stability.

  14. A computational study of the aerodynamic performance of a dragonfly wing section in gliding flight.

    PubMed

    Vargas, Abel; Mittal, Rajat; Dong, Haibo

    2008-06-01

    A comprehensive computational fluid-dynamics-based study of a pleated wing section based on the wing of Aeshna cyanea has been performed at ultra-low Reynolds numbers corresponding to the gliding flight of these dragonflies. In addition to the pleated wing, simulations have also been carried out for its smoothed counterpart (called the 'profiled' airfoil) and a flat plate in order to better understand the aerodynamic performance of the pleated wing. The simulations employ a sharp interface Cartesian-grid-based immersed boundary method, and a detailed critical assessment of the computed results was performed giving a high measure of confidence in the fidelity of the current simulations. The simulations demonstrate that the pleated airfoil produces comparable and at times higher lift than the profiled airfoil, with a drag comparable to that of its profiled counterpart. The higher lift and moderate drag associated with the pleated airfoil lead to an aerodynamic performance that is at least equivalent to and sometimes better than the profiled airfoil. The primary cause for the reduction in the overall drag of the pleated airfoil is the negative shear drag produced by the recirculation zones which form within the pleats. The current numerical simulations therefore clearly demonstrate that the pleated wing is an ingenious design of nature, which at times surpasses the aerodynamic performance of a more conventional smooth airfoil as well as that of a flat plate. For this reason, the pleated airfoil is an excellent candidate for a fixed wing micro-aerial vehicle design.

  15. Aerodynamic stability and control characteristics of TBC shuttle booster AR-11981-3

    NASA Technical Reports Server (NTRS)

    Phelps, E. R.; Watts, L. L.; Ainsworth, R. W.

    1972-01-01

    A scale model of the Boeing Company space shuttle booster configuration 3 was tested in the MSFC 14-inch trisonic wind tunnel. This test was proposed to fill-in the original test run schedule as well as to investigate the aerodynamic stability and control characteristics of the booster with three wing configurations not previously tested. The configurations tested included: (1) a cylindrical booster body with an axisymmetric nose, (2) clipped delta canards that had variable incidence from 0 deg to -60 deg, (3) different aft body mounted wing configurations, (4) two vertical fin configurations, and (5) a Grumman G-3 orbiter configuration. Tests were conducted over a Mach range from 0.6 to 5.0.

  16. An experimental investigation of the aerodynamic characteristics of slanted base ogive cylinders using magnetic suspension technology

    NASA Technical Reports Server (NTRS)

    Alcorn, Charles W.; Britcher, Colin

    1988-01-01

    An experimental investigation is reported on slanted base ogive cylinders at zero incidence. The Mach number range is 0.05 to 0.3. All flow disturbances associated with wind tunnel supports are eliminated in this investigation by magnetically suspending the wind tunnel models. The sudden and drastic changes in the lift, pitching moment, and drag for a slight change in base slant angle are reported. Flow visualization with liquid crystals and oil is used to observe base flow patterns, which are responsible for the sudden changes in aerodynamic characteristics. Hysteretic effects in base flow pattern changes are present in this investigation and are reported. The effect of a wire support attachment on the 0 deg slanted base model is studied. Computational drag and transition location results using VSAERO and SANDRAG are presented and compared with experimental results. Base pressure measurements over the slanted bases are made with an onboard pressure transducer using remote data telemetry.

  17. Calculation of the longitudinal aerodynamic characteristics of upper-surface-blown wing-flap configurations

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Spangler, S. B.

    1979-01-01

    An investigation has been carried out to develop an engineering method for predicting the longitudinal aerodynamic characteristics of wing-flap configurations with upper surface blown (USB) high lift devices. Potential flow models of the lifting surfaces and the jet wakes are combined to calculate the induced interference of the engine wakes on the wing and flaps. The wing may have an arbitrary planform with camber and twist and multiple trailing edge flaps. The jet wake model has a rectangular cross section over its entire length and it is positioned such that the wake is tangent to the upper surfaces of the wing and flaps. Comparisons of measured and predicted pressure distributions, spanload distributions, and total lift and pitching-moment coefficients on swept and unswept USB configurations are presented for a wide range of thrust coefficients and flap deflection angles.

  18. Prediction of longitudinal aerodynamic characteristics of STOL configurations with externally blown high lift devices

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Spangler, S. B.

    1976-01-01

    A theoretical method has been developed to predict the longitudinal aerodynamic characteristics of engine-wing-flap combinations with externally blown flaps (EBF) and upper surface blowing (USB) high lift devices. Potential flow models of the lifting surfaces and the jet wake are combined to calculate the induced interference of the engine wakes on the lifting surfaces. The engine wakes may be circular, elliptic, or rectangular cross-sectional jets, and the lifting surfaces are comprised of a wing with multiple-slotted trailing-edge flaps or a deflected trailing-edge Coanda surface. Results are presented showing comparisons of measured and predicted forces, pitching moments, span-load distributions, and flow fields.

  19. Subsonic longitudinal and lateral aerodynamic characteristics for a systematic series of strake-wing configurations

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    1979-01-01

    A systematic wind tunnel study was conducted in the Langley 7 by 10 foot high speed tunnel to help establish a parametric data base of the longitudinal and lateral aerodynamic characteristics for configurations incorporating strake-wing geometries indicative of current and proposed maneuvering aircraft. The configurations employed combinations of strakes with reflexed planforms having exposed spans of 10%, 20%, and 30% of the reference wing span and wings with trapezoidal planforms having leading edge sweep angles of approximately 30, 40, 44, 50, and 60 deg. Tests were conducted at Mach numbers ranging from 0.3 to 0.8 and at angles of attack from approximately -4 to 48 deg at zero sideslip.

  20. Low speed aerodynamic characteristics of a 17 percent thick airfoil section designed for general aviation applications

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Beasley, W. D.

    1973-01-01

    Wind-tunnel tests have been conducted to determine the low-speed two-dimensional aerodynamic characteristics of a 17-percent-thick airfoil designed for general aviation applications (GA(W)-1). The results were compared with predictions based on a theoretical method for calculating the viscous flow about the airfoil. The tests were conducted over a Mach number range from 0.10 to 0.28. Reynolds numbers based on airfoil chord varied from 2.0 million to 20.0 million. Maximum section lift coefficients greater than 2.0 were obtained and section lift-drag ratio at a lift coefficient of 1.0 (climb condition) varied from about 65 to 85 as the Reynolds number increased from about 2.0 million to 6.0 million.

  1. Calculation of the longitudinal aerodynamic characteristics of wing-flap configurations with externally blown flaps

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.

    1976-01-01

    An analytical method for predicting the longitudinal aerodynamic characteristics of externally blown flap configurations is described. Two potential flow models make up the prediction method: a wing and flap lifting-surface model and a turbofan engine wake model. A vortex-lattice lifting-surface method is used to represent the wing and multiple-slotted trailing-edge flaps. The jet wake is represented by a series of closely spaced vortex rings normal to a centerline which is free to move to conform to the local flow field. The two potential models are combined in an iterative fashion to predict the jet wake interference effects on a typical EBF configuration. Comparisons of measured and predicted span-load distributions, individual surface forces, forces and moments on the complete configuration, and flow fields are included.

  2. A simulator investigation of the influence of engine response characteristics on the approach and landing for an externally blown flap aircraft. Part 2: Aerodynamic model

    NASA Technical Reports Server (NTRS)

    Ciffone, D. L.; Robinson, G. H.

    1973-01-01

    An analysis of the influence of engine response characteristics on the approach and landing of an externally blown flap aircraft was conducted using flight simulator facilities. The configuration of the aerodynamic model is described. The aerodynamic characteristics as a function of angle of attack, thrust coefficient, and flap deflection are presented in tabular form and as graphs.

  3. Aerodynamic performance of an annular flat plate airfoil cascade with nonuniform inlet velocity

    NASA Technical Reports Server (NTRS)

    Buffum, D.; Fleeter, S.

    1986-01-01

    The demand for increased gas turbine engine efficiency with minimum weight is leading to more complex blading designs, in which viscous and three-dimensional effects are significant. As a result, design procedures based on first principle, experimentally verified, three-dimensional aerodynamic analyses are required. This paper describes a series of experiments performed in a large-scale, subsonic, annular cascade facility specifically designed to provide three-dimensional aerodynamic data suitable for code verification. In particular, the effect of inlet velocity profile on the overall three-dimensional performance of a classical flat plate airfoil cascade is investigated over a range of incidence angles including those resulting in airfoil surface flow separation. All of the data are analyzed and correlated with appropriate nonseparated flow predictions.

  4. Aerodynamic/acoustic performance of YJ101/double bypass VCE with coannular plug nozzle

    NASA Technical Reports Server (NTRS)

    Vdoviak, J. W.; Knott, P. R.; Ebacker, J. J.

    1981-01-01

    Results of a forward Variable Area Bypass Injector test and a Coannular Nozzle test performed on a YJ101 Double Bypass Variable Cycle Engine are reported. These components are intended for use on a Variable Cycle Engine. The forward Variable Area Bypass Injector test demonstrated the mode shifting capability between single and double bypass operation with less than predicted aerodynamic losses in the bypass duct. The acoustic nozzle test demonstrated that coannular noise suppression was between 4 and 6 PNdB in the aft quadrant. The YJ101 VCE equipped with the forward VABI and the coannular exhaust nozzle performed as predicted with exhaust system aerodynamic losses lower than predicted both in single and double bypass modes. Extensive acoustic data were collected including far field, near field, sound separation/ internal probe measurements as Laser Velocimeter traverses.

  5. Aerodynamic Analysis of Cup Anemometers Performance: The Stationary Harmonic Response

    PubMed Central

    Pindado, Santiago; Cubas, Javier; Sanz-Andrés, Ángel

    2013-01-01

    The effect of cup anemometer shape parameters, such as the cups' shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor's movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer's rotor and the mentioned third harmonic term of its movement. PMID:24381512

  6. Aerodynamic analysis of cup anemometers performance: the stationary harmonic response.

    PubMed

    Pindado, Santiago; Cubas, Javier; Sanz-Andrés, Angel

    2013-01-01

    The effect of cup anemometer shape parameters, such as the cups' shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor's movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer's rotor and the mentioned third harmonic term of its movement.

  7. Effect of Length-Beam Ratio on the Aerodynamic Characteristics of Flying-Boat Hulls without Wing Interference

    NASA Technical Reports Server (NTRS)

    Lowry, John G.; Riebe, John M.

    1948-01-01

    Contains experimental results of an investigation of the aerodynamic characteristics of a family of flying boat hulls of length beam ratios 6, 9, 12, and 15 without wing interference. The results are compared with those taken on the same family of hulls in the presence of a wing.

  8. Aerodynamic Characteristics of a Revised Target Drone Vehicle at Mach Numbers from 1.60 to 2.86

    NASA Technical Reports Server (NTRS)

    Blair, A. B., Jr.; Babb, C. Donald

    1968-01-01

    An investigation has been conducted in the Langley Unitary Plan wind tunnel to determine the aerodynamic characteristics of a revised target drone vehicle through a Mach number range from 1.60 to 2.86. The vehicle had canard surfaces and a swept clipped-delta wing with twin tip-mounted vertical tails.

  9. Aerodynamic characteristics of a wing with Fowler flaps including flap loads, downwash, and calculated effect on take-off

    NASA Technical Reports Server (NTRS)

    Platt, Robert C

    1936-01-01

    This report presents the results of wind tunnel tests of a wing in combination with each of three sizes of Fowler flap. The purpose of the investigation was to determine the aerodynamic characteristics as affected by flap chord and position, the air loads on the flaps, and the effect of flaps on the downwash.

  10. A performance index approach to aerodynamic design with the use of analysis codes only

    NASA Technical Reports Server (NTRS)

    Barger, Raymond L.; Moitra, Anutosh

    1988-01-01

    A method is described for designing an aerodynamic configuration for a specified performance vector, based on results from several similar, but not identical, trial configurations, each defined by a geometry parameter vector. The theory shows the method effective provided that: (1) the results for the trial configuration provide sufficient variation so that a linear combination of them approximates the specified performance; and (2) the difference between the performance vectors (including the specifed performance) are sufficiently small that the linearity assumption of sensitivity analysis applies to the differences. A computed example describes the design of a high supersonic Mach number missile wing body configuration based on results from a set of four trial configurations.

  11. Charts Showing Relations Among Primary Aerodynamic Variables for Helicopter-performance Estimation

    NASA Technical Reports Server (NTRS)

    Talkin, Herbert W

    1947-01-01

    In order to facilitate solutions of the general problem of helicopter selection, the aerodynamic performance of rotors is presented in the form of charts showing relations between primary design and performance variables. By the use of conventional helicopter theory, certain variables are plotted and other variables are considered fixed. Charts constructed in such a manner show typical results, trends, and limits of helicopter performance. Performance conditions considered include hovering, horizontal flight, climb, and ceiling. Special problems discussed include vertical climb and the use of rotor-speed-reduction gears for hovering.

  12. Neural Net-Based Redesign of Transonic Turbines for Improved Unsteady Aerodynamic Performance

    NASA Technical Reports Server (NTRS)

    Madavan, Nateri K.; Rai, Man Mohan; Huber, Frank W.

    1998-01-01

    A recently developed neural net-based aerodynamic design procedure is used in the redesign of a transonic turbine stage to improve its unsteady aerodynamic performance. The redesign procedure used incorporates the advantages of both traditional response surface methodology (RSM) and neural networks by employing a strategy called parameter-based partitioning of the design space. Starting from the reference design, a sequence of response surfaces based on both neural networks and polynomial fits are constructed to traverse the design space in search of an optimal solution that exhibits improved unsteady performance. The procedure combines the power of neural networks and the economy of low-order polynomials (in terms of number of simulations required and network training requirements). A time-accurate, two-dimensional, Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the optimization procedure. The optimization procedure yields a modified design that improves the aerodynamic performance through small changes to the reference design geometry. The computed results demonstrate the capabilities of the neural net-based design procedure, and also show the tremendous advantages that can be gained by including high-fidelity unsteady simulations that capture the relevant flow physics in the design optimization process.

  13. Improving the Unsteady Aerodynamic Performance of Transonic Turbines using Neural Networks

    NASA Technical Reports Server (NTRS)

    Rai, Man Mohan; Madavan, Nateri K.; Huber, Frank W.

    1999-01-01

    A recently developed neural net-based aerodynamic design procedure is used in the redesign of a transonic turbine stage to improve its unsteady aerodynamic performance. The redesign procedure used incorporates the advantages of both traditional response surface methodology and neural networks by employing a strategy called parameter-based partitioning of the design space. Starting from the reference design, a sequence of response surfaces based on both neural networks and polynomial fits are constructed to traverse the design space in search of an optimal solution that exhibits improved unsteady performance. The procedure combines the power of neural networks and the economy of low-order polynomials (in terms of number of simulations required and network training requirements). A time-accurate, two-dimensional, Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the optimization procedure. The procedure yielded a modified design that improves the aerodynamic performance through small changes to the reference design geometry. These results demonstrate the capabilities of the neural net-based design procedure, and also show the advantages of including high-fidelity unsteady simulations that capture the relevant flow physics in the design optimization process.

  14. Aerodynamic performance of a transonic low aspect ratio turbine nozzle

    SciTech Connect

    Moustapha, S.H. . Turbine Aerodynamics); Carscallen, W.E. . Combustion and Fluids Engineering Lab.); McGeachy, J.D. . Dept. of Mechanical Engineering)

    1993-07-01

    This paper presents detailed information of the three-dimensional flow field in a realistic turbine nozzle with an aspect ratio of 0.65 and a turning angle of 76 deg. The nozzle has been tested in a large-scale planar cascade over a range of exit Mach numbers from 0.3 to 1.3. The experimental results are presented in the form of nozzle passage Mach number distributions and spanwise distribution of losses and exit flow angle. Details of the flow field inside the nozzle passage are examined by means of surface flow visualization and Schlieren pictures. The performance of the nozzle is compared to the data obtained for the same nozzle tested in an annular cascade and a stage environment. Excellent agreement is found between the measured pressure distribution and the prediction of a three-dimensional Euler flow solver.

  15. On the aerodynamic characteristics of hovering rigid and flexible hawkmoth-like wings

    NASA Astrophysics Data System (ADS)

    Lua, K. B.; Lai, K. C.; Lim, T. T.; Yeo, K. S.

    2010-12-01

    Insect wings are subjected to fluid, inertia and gravitational forces during flapping flight. Owing to their limited rigidity, they bent under the influence of these forces. Numerical study by Hamamoto et al. (Adv Robot 21(1-2):1-21, 2007) showed that a flexible wing is able to generate almost as much lift as a rigid wing during flapping. In this paper, we take a closer look at the relationship between wing flexibility (or stiffness) and aerodynamic force generation in flapping hovering flight. The experimental study was conducted in two stages. The first stage consisted of detailed force measurement and flow visualization of a rigid hawkmoth-like wing undergoing hovering hawkmoth flapping motion and simple harmonic flapping motion, with the aim of establishing a benchmark database for the second stage, which involved hawkmoth-like wing of different flexibility performing the same flapping motions. Hawkmoth motion was conducted at Re = 7,254 and reduced frequency of 0.26, while simple harmonic flapping motion at Re = 7,800 and 11,700, and reduced frequency of 0.25. Results show that aerodynamic force generation on the rigid wing is governed primarily by the combined effect of wing acceleration and leading edge vortex generated on the upper surface of the wing, while the remnants of the wake vortices generated from the previous stroke play only a minor role. Our results from the flexible wing study, while generally supportive of the finding by Hamamoto et al. (Adv Robot 21(1-2):1-21, 2007), also reveal the existence of a critical stiffness constant, below which lift coefficient deteriorates significantly. This finding suggests that although using flexible wing in micro air vehicle application may be beneficial in term of lightweight, too much flexibility can lead to deterioration in flapping performance in terms of aerodynamic force generation. The results further show that wings with stiffness constant above the critical value can deliver mean lift coefficient

  16. Aerodynamic characteristics of a distinct wing-body configuration at Mach 6: Experiment, theory, and the hypersonic isolation principle

    NASA Technical Reports Server (NTRS)

    Penland, J. A.; Pittman, J. L.

    1985-01-01

    An experimental investigation has been conducted to determine the effect of wing leading edge sweep and wing translation on the aerodynamic characteristics of a wing body configuration at a free stream Mach number of about 6 and Reynolds number (based on body length) of 17.9 x 10 to the 6th power. Seven wings with leading edge sweep angles from -20 deg to 60 deg were tested on a common body over an angle of attack range from -12 deg to 10 deg. All wings had a common span, aspect ratio, taper ratio, planform area, and thickness ratio. Wings were translated longitudinally on the body to make tests possible with the total and exposed mean aerodynamic chords located at a fixed body station. Aerodynamic forces were found to be independent of wing sweep and translation, and pitching moments were constant when the exposed wing mean aerodynamic chord was located at a fixed body station. Thus, the Hypersonic Isolation Principle was verified. Theory applied with tangent wedge pressures on the wing and tangent cone pressures on the body provided excellent predictions of aerodynamic force coefficients but poor estimates of moment coefficients.

  17. Aerodynamic Parameters of High Performance Aircraft Estimated from Wind Tunnel and Flight Test Data

    NASA Technical Reports Server (NTRS)

    Klein, Vladislav; Murphy, Patrick C.

    1998-01-01

    A concept of system identification applied to high performance aircraft is introduced followed by a discussion on the identification methodology. Special emphasis is given to model postulation using time invariant and time dependent aerodynamic parameters, model structure determination and parameter estimation using ordinary least squares an mixed estimation methods, At the same time problems of data collinearity detection and its assessment are discussed. These parts of methodology are demonstrated in examples using flight data of the X-29A and X-31A aircraft. In the third example wind tunnel oscillatory data of the F-16XL model are used. A strong dependence of these data on frequency led to the development of models with unsteady aerodynamic terms in the form of indicial functions. The paper is completed by concluding remarks.

  18. Effect of posture on the aerodynamic characteristics during take-off in ski jumping.

    PubMed

    Yamamoto, Keizo; Tsubokura, Makoto; Ikeda, Jun; Onishi, Keiji; Baleriola, Sophie

    2016-11-07

    The purpose of this study was to investigate the effects of posture of a ski jumper on aerodynamic characteristics during the take-off using computational fluid dynamics (CFD). The CFD method adopted for this study was based on Large-Eddy Simulation. Body surface data were obtained by 3-D laser scanning of an active ski jumper. Based on video analysis of the actual take-off movement, two sets of motion data were generated (world-class jumper A and less-experienced jumper B). The inlet flow velocity that corresponds to the in-run velocity in actual ski jumping was set to 23.23m/s in the CFD. The aerodynamic force, flow velocity, and vortexes for each model were compared between models. The total drag force acting upon jumper A was lower than that acting upon jumper B through the whole movement. Regarding the total lift force, although jumper A׳s total lift force was less in the in-run posture, it became greater than that of jumper B at the end of the movement. In the latter half of the movement, low air-speed domain expansion was observed at the model׳s back. This domain of jumper B was larger. There were two symmetric vortexes in the wake of jumper A, but the disordered vortexes were observed behind the jumper B. In the case of jumper A, these two distinct vortexes generated by the arms produced a downwash flow in the wake. It is considered that the positioning of the arms in a very low position strongly influences the flow structure.

  19. Experimental analysis of the aerodynamic performance of an innovative low pressure turbine rotor

    NASA Astrophysics Data System (ADS)

    Infantino, Daniele; Satta, Francesca; Simoni, Daniele; Ubaldi, Marina; Zunino, Pietro; Bertini, Francesco

    2016-02-01

    In the present work the aerodynamic performances of an innovative rotor blade row have been experimentally investigated. Measurements have been carried out in a large scale low speed single stage cold flow facility at a Reynolds number typical of aeroengine cruise, under nominal and off-design conditions. The time-mean blade aerodynamic loadings have been measured at three radial positions along the blade height through a pressure transducer installed inside the hollow shaft, by delivering the signal to the stationary frame with a slip ring. The time mean aerodynamic flow fields upstream and downstream of the rotor have been measured by means of a five-hole probe to investigate the losses associated with the rotor. The investigations in the single stage research turbine allow the reproduction of both wake-boundary layer interaction as well as vortex-vortex interaction. The detail of the present results clearly highlights the strong dissipative effects induced by the blade tip vortex and by the momentum defect as well as the turbulence production, which is generated during the migration of the stator wake in the rotor passage. Phase-locked hot-wire investigations have been also performed to analyze the time-varying flow during the wake passing period. In particular the interaction between stator and rotor structures has been investigated also under off-design conditions to further explain the mechanisms contributing to the loss generation for the different conditions.

  20. Low Speed Aerodynamic Characteristics of Wings of Aspect Ratios 3 and 4 Equipped with High Lift Systems

    DTIC Science & Technology

    1980-05-01

    Trailing Edge in CCW Configuration without Tip Fence ................. ... 47 16 - Effect of a Nonround Coanda Trailing Edge on an Aspect Ratio 3 Wing in...fence installed. Figure 16 summarizes the effect of the noncircular Coanda surface on the lift characteristics. The aerodynamic characteristics of the...that of the round Coanda trailing edge depending on the value of a and C Figure 17 is a crossplot of all of the CCW data showing the effect of a wing tip

  1. Mathematical description of nonstationary aerodynamic characteristics of a passenger aircraft model in longitudinal motion at large angles of attack

    NASA Astrophysics Data System (ADS)

    Petoshin, V. I.; Chasovnikov, E. A.

    2011-05-01

    Aerodynamic loads in problems of flight dynamics of passenger aircraft in stalled flow regimes are described using a mathematical model that includes an ordinary linear first-order differential equation. A procedure for determining the parameters of the mathematical model is proposed which is based on approximating experimental frequency characteristics with the frequency characteristics of the linearized mathematical model. The mathematical model was verified by tests of a modern passenger aircraft model in a wind tunnel.

  2. High fidelity quasi steady-state aerodynamic model effects on race vehicle performance predictions using multi-body simulation

    NASA Astrophysics Data System (ADS)

    Mohrfeld-Halterman, J. A.; Uddin, M.

    2016-07-01

    We described in this paper the development of a high fidelity vehicle aerodynamic model to fit wind tunnel test data over a wide range of vehicle orientations. We also present a comparison between the effects of this proposed model and a conventional quasi steady-state aerodynamic model on race vehicle simulation results. This is done by implementing both of these models independently in multi-body quasi steady-state simulations to determine the effects of the high fidelity aerodynamic model on race vehicle performance metrics. The quasi steady state vehicle simulation is developed with a multi-body NASCAR Truck vehicle model, and simulations are conducted for three different types of NASCAR race tracks, a short track, a one and a half mile intermediate track, and a higher speed, two mile intermediate race track. For each track simulation, the effects of the aerodynamic model on handling, maximum corner speed, and drive force metrics are analysed. The accuracy of the high-fidelity model is shown to reduce the aerodynamic model error relative to the conventional aerodynamic model, and the increased accuracy of the high fidelity aerodynamic model is found to have realisable effects on the performance metric predictions on the intermediate tracks resulting from the quasi steady-state simulation.

  3. Analysis and compilation of missile aerodynamic data. Volume 2: Performance analysis

    NASA Technical Reports Server (NTRS)

    Burkhalter, J. E.

    1977-01-01

    A general analysis is given of the flight dynamics of several surface-to-air and two air-to-air missile configurations. The analysis involves three phases: vertical climb, straight and level flight, and constant altitude turn. Wind tunnel aerodynamic data and full scale missile characteristics are used where available; unknown data are estimated. For the constant altitude turn phase, a three degree of freedom flight simulation is used. Important parameters considered in this analysis are the vehicle weight, Mach number, heading angle, thrust level, sideslip angle, g loading, and time to make the turn. The actual flight path during the turn is also determined. Results are presented in graphical form.

  4. An Assessment of NASA Glenn's Aeroacoustic Experimental and Predictive Capabilities for Installed Cooling Fans. Part 1; Aerodynamic Performance

    NASA Technical Reports Server (NTRS)

    VanZante, Dale E.; Koch, L. Danielle; Wernet, Mark P.; Podboy, Gary G.

    2006-01-01

    Driven by the need for low production costs, electronics cooling fans have evolved differently than the bladed components of gas turbine engines which incorporate multiple technologies to enhance performance and durability while reducing noise emissions. Drawing upon NASA Glenn's experience in the measurement and prediction of gas turbine engine aeroacoustic performance, tests have been conducted to determine if these tools and techniques can be extended for application to the aerodynamics and acoustics of electronics cooling fans. An automated fan plenum installed in NASA Glenn's Acoustical Testing Laboratory was used to map the overall aerodynamic and acoustic performance of a spaceflight qualified 80 mm diameter axial cooling fan. In order to more accurately identify noise sources, diagnose performance limiting aerodynamic deficiencies, and validate noise prediction codes, additional aerodynamic measurements were recorded for two operating points: free delivery and a mild stall condition. Non-uniformities in the fan s inlet and exhaust regions captured by Particle Image Velocimetry measurements, and rotor blade wakes characterized by hot wire anemometry measurements provide some assessment of the fan aerodynamic performance. The data can be used to identify fan installation/design changes which could enlarge the stable operating region for the fan and improve its aerodynamic performance and reduce noise emissions.

  5. Low-speed longitudinal aerodynamic characteristics of a flat-plate planform model of an advanced fighter configuration

    NASA Technical Reports Server (NTRS)

    Mcgrath, Brian E.; Neuhart, Dan H.; Gatlin, Gregory M.; Oneil, Pat

    1994-01-01

    A flat-plate wind tunnel model of an advanced fighter configuration was tested in the NASA LaRC Subsonic Basic Research Tunnel and the 16- by 24-inch Water Tunnel. The test objectives were to obtain and evaluate the low-speed longitudinal aerodynamic characteristics of a candidate configuration for the integration of several new innovative wing designs. The flat plate test allowed for the initial evaluation of the candidate planform and was designated as the baseline planform for the innovative wing design study. Low-speed longitudinal aerodynamic data were obtained over a range of freestream dynamic pressures from 7.5 psf to 30 psf (M = 0.07 to M = 0.14) and angles-of-attack from 0 to 40 deg. The aerodynamic data are presented in coefficient form for the lift, induced drag, and pitching moment. Flow-visualization results obtained were photographs of the flow pattern over the flat plate model in the water tunnel for angles-of-attack from 10 to 40 deg. The force and moment coefficients and the flow-visualization photographs showed the linear and nonlinear aerodynamic characteristics due to attached flow and vortical flow over the flat plate model. Comparison between experiment and linear theory showed good agreement for the lift and induced drag; however, the agreement was poor for the pitching moment.

  6. Advanced missile technology. A review of technology improvement areas for cruise missiles. [including missile design, missile configurations, and aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Cronvich, L. L.; Liepman, H. P.

    1979-01-01

    Technology assessments in the areas of aerodynamics, propulsion, and structures and materials for cruise missile systems are discussed. The cruise missiles considered cover the full speed, altitude, and target range. The penetrativity, range, and maneuverability of the cruise missiles are examined and evaluated for performance improvements.

  7. Aerodynamic Performance of Scale-Model Turbofan Outlet Guide Vanes Designed for Low Noise

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.

    2001-01-01

    The design of effective new technologies to reduce aircraft propulsion noise is dependent on an understanding of the noise sources and noise generation mechanisms in the modern turbofan engine. In order to more fully understand the physics of noise in a turbofan engine, a comprehensive aeroacoustic wind tunnel test programs was conducted called the 'Source Diagnostic Test.' The text was cooperative effort between NASA and General Electric Aircraft Engines, as part of the NASA Advanced Subsonic Technology Noise Reduction Program. A 1/5-scale model simulator representing the bypass stage of a current technology high bypass ratio turbofan engine was used in the test. The test article consisted of the bypass fan and outlet guide vanes in a flight-type nacelle. The fan used was a medium pressure ratio design with 22 individual, wide chord blades. Three outlet guide vane design configurations were investigated, representing a 54-vane radial Baseline configuration, a 26-vane radial, wide chord Low Count configuration and a 26-vane, wide chord Low Noise configuration with 30 deg of aft sweep. The test was conducted in the NASA Glenn Research Center 9 by 15-Foot Low Speed Wind Tunnel at velocities simulating the takeoff and approach phases of the aircraft flight envelope. The Source Diagnostic Test had several acoustic and aerodynamic technical objectives: (1) establish the performance of a scale model fan selected to represent the current technology turbofan product; (2) assess the performance of the fan stage with each of the three distinct outlet guide vane designs; (3) determine the effect of the outlet guide vane configuration on the fan baseline performance; and (4) conduct detailed flowfield diagnostic surveys, both acoustic and aerodynamic, to characterize and understand the noise generation mechanisms in a turbofan engine. This paper addresses the fan and stage aerodynamic performance results from the Source Diagnostic Test.

  8. Aerodynamic characteristics of a rotorcraft airfoil designed for the tip region of a main rotor blade

    NASA Technical Reports Server (NTRS)

    Noonan, Kevin W.

    1991-01-01

    A wind tunnel investigation was conducted to determine the 2-D aerodynamic characteristics of a new rotorcraft airfoil designed for application to the tip region (stations outboard of 85 pct. radius) of a helicopter main rotor blade. The new airfoil, the RC(6)-08, and a baseline airfoil, the RC(3)-08, were investigated in the Langley 6- by 28-inch transonic tunnel at Mach numbers from 0.37 to 0.90. The Reynolds number varied from 5.2 x 10(exp 6) at the lowest Mach number to 9.6 x 10(exp 6) at the highest Mach number. Some comparisons were made of the experimental data for the new airfoil and the predictions of a transonic, viscous analysis code. The results of the investigation indicate that the RC(6)-08 airfoil met the design goals of attaining higher maximum lift coefficients than the baseline airfoil while maintaining drag divergence characteristics at low lift and pitching moment characteristics nearly the same as those of the baseline airfoil. The maximum lift coefficients of the RC(6)-08 varied from 1.07 at M=0.37 to 0.94 at M=0.52 while those of the RC(3)-08 varied from 0.91 to 0.85 over the same Mach number range. At lift coefficients of -0.1 and 0, the drag divergence Mach number of both the RC(6)-08 and the RC(3)-08 was 0.86. The pitching moment coefficients of the RC(6)-08 were less negative than those of the RC(3)-08 for Mach numbers and lift coefficients typical of those that would occur on a main rotor blade tip at high forward speeds on the advancing side of the rotor disk.

  9. Laboratory evaluation of fan/filter units' aerodynamic and energy performance

    SciTech Connect

    Xu, Tengfang; Jeng, Ming-Shan

    2004-07-27

    The paper discusses the benefits of having a consistent testing method to characterize aerodynamic and energy performance of FFUs. It presents evaluation methods of laboratory-measured performance of ten relatively new, 1220 mm x 610 mm (or 4 ft x 2 ft) fan-filter units (FFUs), and includes results of a set of relevant metrics such as energy performance indices (EPI) based upon the sample FFUs tested. This paper concludes that there are variations in FFUs' performance, and that using a consistent testing and evaluation method can generate compatible and comparable FFU performance information. The paper also suggests that benefits and opportunities exist for our method of testing FFU energy performance to be integrated in future recommended practices.

  10. The effect of prewhirl on the internal aerodynamics and performance of a mixed flow research centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Bryan, William B.; Fleeter, Sanford

    1987-01-01

    The internal three-dimensional steady and time-varying flow through the diffusing elements of a centrifugal impeller were investigated using a moderate scale, subsonic, mixed flow research compressor facility. The characteristics of the test facility which permit the measurement of internal flow conditions throughout the entire research compressor and radial diffuser for various operating conditions are described. Results are presented in the form of graphs and charts to cover a range of mass flow rates with inlet guide vane settings varying from minus 15 degrees to plus 45 degrees. The static pressure distributions in the compressor inlet section and on the impeller and exit diffuser vanes, as well as the overall pressure and temperature rise and mass flow rate, were measured and analyzed at each operating point to determine the overall performance as well as the detailed aerodynamics throughout the compressor.

  11. Acoustic and aerodynamic performance investigation of inverted velocity profile coannular plug nozzles. [variable cycle engines

    NASA Technical Reports Server (NTRS)

    Knott, P. R.; Blozy, J. T.; Staid, P. S.

    1981-01-01

    The results of model scale parametric static and wind tunnel aerodynamic performance tests on unsuppressed coannular plug nozzle configurations with inverted velocity profile are discussed. The nozzle configurations are high-radius-ratio coannular plug nozzles applicable to dual-stream exhaust systems typical of a variable cycle engine for Advanced Supersonic Transport application. In all, seven acoustic models and eight aerodynamic performance models were tested. The nozzle geometric variables included outer stream radius ratio, inner stream to outer stream ratio, and inner stream plug shape. When compared to a conical nozzle at the same specific thrust, the results of the static acoustic tests with the coannular nozzles showed noise reductions of up to 7 PNdB. Extensive data analysis showed that the overall acoustic results can be well correlated using the mixed stream velocity and the mixed stream density. Results also showed that suppression levels are geometry and flow regulation dependent with the outer stream radius ratio, inner stream-to-outer stream velocity ratio and inner stream velocity ratio and inner stream plug shape, as the primary suppression parameters. In addition, high-radius ratio coannular plug nozzles were found to yield shock associated noise level reductions relative to a conical nozzle. The wind tunnel aerodynamic tests showed that static and simulated flight thrust coefficient at typical takeoff conditions are quite good - up to 0.98 at static conditions and 0.974 at a takeoff Mach number of 0.36. At low inner stream flow conditions significant thrust loss was observed. Using an inner stream conical plug resulted in 1% to 2% higher performance levels than nozzle geometries using a bent inner plug.

  12. Improvement of aerodynamic characteristics of a thick airfoil with a vortex cell in sub- and transonic flow

    NASA Astrophysics Data System (ADS)

    Isaev, Sergey; Baranov, Paul; Popov, Igor; Sudakov, Alexander; Usachov, Alexander

    2017-03-01

    The modified SST model (2005) is verified using Rodi- Leschziner-Isaev's approach and the multiblock computational technologies are validated in the VP2/3 code on different-structure overlapping grids by comparing the numerical predictions with the experimental data on transonic flow around an NACA0012 airfoil at an angle of attack of 4o for M=0.7 and Re=4×106. It is proved that the aerodynamic characteristics of a thick (20% of the chord) MQ airfoil mounted at an angle of attack of 2o for Re=107 and over the Mach number range 0.3-0.55 are significantly improved because an almost circular small-size (0.12) vortex cell with a defined volumetric flow rate coefficient of 0.007 during slot suction has been located on the upper airfoil section and an intense trapped vortex has been formed in it. A detailed analysis of buffeting within the self-oscillatory regime of flow around the MQ airfoil with a vortex cell has demonstrated the periodic changes in local and integral characteristics; the lift and the aerodynamic efficiency remain quite high, but inferior to the similar characteristics at M=0.55. It is found that the vortex cell at M=0.7 is inactive, and the aerodynamic characteristics of the MQ airfoil with a vortex cell are close to those of a smooth airfoil without a cell.

  13. Program VSAERO theory document: A computer program for calculating nonlinear aerodynamic characteristics of arbitrary configurations

    NASA Technical Reports Server (NTRS)

    Maskew, Brian

    1987-01-01

    The VSAERO low order panel method formulation is described for the calculation of subsonic aerodynamic characteristics of general configurations. The method is based on piecewise constant doublet and source singularities. Two forms of the internal Dirichlet boundary condition are discussed and the source distribution is determined by the external Neumann boundary condition. A number of basic test cases are examined. Calculations are compared with higher order solutions for a number of cases. It is demonstrated that for comparable density of control points where the boundary conditions are satisfied, the low order method gives comparable accuracy to the higher order solutions. It is also shown that problems associated with some earlier low order panel methods, e.g., leakage in internal flows and junctions and also poor trailing edge solutions, do not appear for the present method. Further, the application of the Kutta conditions is extremely simple; no extra equation or trailing edge velocity point is required. The method has very low computing costs and this has made it practical for application to nonlinear problems requiring iterative solutions for wake shape and surface boundary layer effects.

  14. An experimental study of the aerodynamic characteristics of planar and non-planar outboard wing planforms

    NASA Technical Reports Server (NTRS)

    Naik, D. A.; Ostowari, C.

    1987-01-01

    A series of wind tunnel experiments have been conducted to investigate the aerodynamic characteristics of several planar and nonplanar wingtip planforms. Seven different configurations: base-line rectangular, elliptical, swept and tapered, swept and tapered with dihedral, swept and tapered with anhedral, rising arc, and drooping arc, were investigated for two different spans. The data are available in terms of coefficient plots of force data, flow visualization photographs, and velocity and pressure flowfield surveys. All planforms, particularly the nonplanar, have some advantages over the baseline rectangular planform. Span efficiencies up to 20-percent greater than baseline are a possibility. However, it is suggested that the span efficiency concept might need refinement for nonplanar wings. Flow survey data show the change in effective span with vortex roll-up. The flow visualization shows the occurrence of mushroom-cell-separation flow patterns at angles of attack corresponding to stall. These grow with an increase in post-stall angle of attack. For the larger aspect ratios, the cells are observed to split into sub-cells at the higher angles of attack. For all angles of attack, some amount of secondary vortex flow is observed for the planar and nonplanar out-board planforms with sweep and taper.

  15. High angle-of-attack aerodynamic characteristics of crescent and elliptic wings

    NASA Technical Reports Server (NTRS)

    Vandam, C. P.

    1989-01-01

    Static longitudinal and lateral-directional forces and moments were measured for elliptic- and crescent-wing models at high angles-of-attack in the NASA Langley 14 by 22-Ft Subsonic Tunnel. The forces and moments were obtained for an angle-of-attack range including stall and post-stall conditions at a Reynolds number based on the average wing chord of about 1.8 million. Flow-visualization photographs using a mixture of oil and titanium-dioxide were also taken for several incidence angles. The force and moment data and the flow-visualization results indicated that the crescent wing model with its highly swept tips produced much better high angle-of-attack aerodynamic characteristics than the elliptic model. Leading-edge separation-induced vortex flow over the highly swept tips of the crescent wing is thought to produce this improved behavior at high angles-of-attack. The unique planform design could result in safer and more efficient low-speed airplanes.

  16. The aerodynamic characteristics of vortex ingestion for the F/A-18 inlet duct

    NASA Technical Reports Server (NTRS)

    Anderson, Bernhard H.

    1991-01-01

    A Reduced Navier-Stokes (RNS) solution technique was successfully combined with the concept of partitioned geometry and mesh generation to form a very efficient 3D RNS code aimed at the analysis-design engineering environment. Partitioned geometry and mesh generation is a pre-processor to augment existing geometry and grid generation programs which allows the solver to (1) recluster an existing gridlife mesh lattice, and (2) perturb an existing gridfile definition to alter the cross-sectional shape and inlet duct centerline distribution without returning to the external geometry and grid generator. The present results provide a quantitative validation of the initial value space marching 3D RNS procedure and demonstrates accurate predictions of the engine face flow field, with a separation present in the inlet duct as well as when vortex generators are installed to supress flow separation. The present results also demonstrate the ability of the 3D RNS procedure to analyze the flow physics associated with vortex ingestion in general geometry ducts such as the F/A-18 inlet. At the conditions investigated, these interactions are basically inviscid like, i.e., the dominant aerodynamic characteristics have their origin in inviscid flow theory.

  17. Aerodynamic characteristics of the Toroidal Accelerator Rotor Platform (TARP) wind energy conversion system

    SciTech Connect

    Not Available

    1980-02-01

    This report describes an analytical and experimental research program that has been conducted at Rensselaer Polytechnic Institute for the purpose of evaluating the aerodynamic characteristics of the Toroidal Accelerator Rotor Platform (TARP) wind energy conversion system. The TARP is an obstruction type flow concentrator and accelerator which converts ambient winds into low pressure, high kinetic energy zones in the immediate proximity of a wind energy conversion unit. A TARP may be described as being substantially the shape of an inner section of a hollow toroid. A twin rotor system of any kind may be mounted within the peripheral flow channel about a TARP structure such that each rotor is situated in the optimum accelerated flow velocity region for best energy recovery. In a series of preliminary experimental tests, the pressure distribution about the basic TARP configuration was obtained at Reynolds numbers based on the TARP's minimum diameter ranging from about 1.1 x 10/sup 5/ to 9.0 x 10/sup 5/.

  18. Aerodynamic characteristics of a 1/6-scale powered model of the rotor systems research aircraft

    NASA Technical Reports Server (NTRS)

    Mineck, R. E.; Freeman, C. E.

    1977-01-01

    A wind-tunnel investigation was conducted to determine the effects of the main-rotor wake on the aerodynamic characteristics of the rotor systems research aircraft (RSRA). For the investigation, a 1/6-scale model with a four-blade articulated main rotor was used. Tests were conducted with and without the main rotor. Both the helicopter and the compound helicopter were tested. The latter configuration included the auxiliary thrust engines and the variable-incidence wing. Data were obtained over ranges of angle of attack, angle of sideslip, and main-rotor collective pitch angle at several main-rotor advance ratios. Results are presented for the total loads on the airframe as well as the loads on the rotor, the wing, and the tail. The results indicated that without the effect of the rotor wake, the RSRA had static longitudinal and directional stability and positive effective dihedral. With the effect of the main rotor and its wake, the RSRA exhibited longitudinal instability but retained static directional stability and positive effective dihedral.

  19. Calculation of the longitudinal aerodynamic characteristics of upper-surface-blown wing-flap configurations

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Spangler, S. B.

    1978-01-01

    An engineering method for predicting the longitudinal aerodynamic characteristics of wing-flap configurations with upper surface blowing (USB) was developed. Potential flow models were incorporated into the prediction method: a wing and flap lifting surface model and a jet wake model. The wing-flap model used a vortex-lattice to represent the wing and flaps. The wing had an arbitrary planform and camber and twist, and the flap system was made up of a Coanda flap and other flap segments of arbitrary size. The jet wake model consisted of a series of closely spaced rectangular vortex rings. The wake was positioned such that it was tangent to the upper surface of the wing and flap between the exhaust nozzle and the flap trailing edge. It was specified such that the mass, momentum, and spreading rates were similar to actual USB jet wakes. Comparisons of measured and predicted pressure distributions, span load distributions, and total lift and pitching-moment coefficients on swept and unswept USB configurations are included. A wide range of thrust coefficients and flap deflection angles were considered at angles of attack up to the onset of stall.

  20. Investigation of Aerodynamic and Icing Characteristics of a Flush Alternate Inlet Induction System Air Scoop

    NASA Technical Reports Server (NTRS)

    Lewis, James P.

    1953-01-01

    An investigation has been made in the NACA Lewis icing research tunnel to determine the aerodynamic and icing characteristics of a full-scale induction-system air-scoop assembly incorporating a flush alternate inlet. The flush inlet was located immediately downstream of the offset ram inlet and included a 180 deg reversal and a 90 deg elbow in the ducting between inlet and carburetor top deck. The model also had a preheat-air inlet. The investigation was made over a range of mass-air- flow ratios of 0 to 0.8, angles of attack of 0 and 4 deg airspeeds of 150 to 270 miles per hour, air temperatures of 0 and 25 F various liquid-water contents, and droplet sizes. The ram inlet gave good pressure recovery in both clear air and icing but rapid blockage of the top-deck screen occurred during icing. The flush alternate inlet had poor pressure recovery in both clear air and icing. The greatest decreases in the alternate-inlet pressure recovery were obtained at icing conditions of low air temperature and high liquid-water content. No serious screen icing was observed with the alternate inlet. Pressure and temperature distributions on the carburetor top deck were determined using the preheat-air supply with the preheat- and alternate-inlet doors in various positions. No screen icing occurred when the preheat-air system was operated in combination with alternate-inlet air flow.

  1. Numerical Analysis on Aerodynamic Characteristics of Delta Wing with Variable Geometry Device in Supersonic Flow

    NASA Astrophysics Data System (ADS)

    Kanamori, Masashi; Imamura, Osamu; Suzuki, Kojiro

    The application of the variable geometry (VG) wing to a lifting re-entry body is expected to enhance the control capability of its aerodynamic characteristics and, as a result, to widen the corridor for the flight trajectory. In the present study, the flow field around a plain delta wing having three chord-wise hinges, one is on the wing root and the others on both sides of the mid-span of the wing, at Mach number 3 is numerically investigated by solving the Euler equations. The effects of the angle of attack and the “tip-down” bending angles around these hinges are clarified. The results show that the lift-to-drag ratio is hardly affected by the tip-down angle and that the overall lift and drag forces vary almost proportional to the change in the projected wing area by taking the tip-down configuration. The center of pressure moves backward by the tip-down effect.

  2. Aerodynamic characteristics of Lockheed delta-body orbiter and stage-and-one-half launch vehicle

    NASA Technical Reports Server (NTRS)

    Velligan, F. A.; Svendsen, H. O.

    1971-01-01

    An experimental wind tunnel test program was conducted to investigate the subsonic through high supersonic aerodynamic characteristics of the Lockheed delta lifting body orbiter and stage-and-one-half launch vehicle. Analyses and results of these data are presented. A 0.01-scale model of the LS 200-5 system was designed and fabricated for testing in wind tunnels. Orbiter and launch configurations were tested over a speed range of Mach 0.6 to 2.0, whereas only the orbiter was tested over a speed range of Mach 2.3 to 4.6. Six-component force and moment data, base pressures, and schlieren photos were obtained at various angles-of-attack and sideslip. A 0.03-scale model of the orbiter was also designed, fabricated, and tested in a wind tunnel. Six-component force and moment data, base pressure, and a limited amount of tuft flow visualization data were obtained on a variety of configuration combinations.

  3. Low-speed, high-lift aerodynamic characteristics of slender, hypersonic accelerator-type configurations

    NASA Technical Reports Server (NTRS)

    Gatlin, Gregory M.

    1989-01-01

    Two investigations were conducted in the Langley 14 by 22 Foot Subsonic Tunnel to determine the low-speed aerodynamic characteristics of a generic hypersonic accelerator-type configuration. The model was a delta wing configuration incorporating a conical forebody, a simulated wrap-around engine package, and a truncated conical aftbody. Six-component force and moment data were obtained over a range of attack from -4 to 30 degrees and for a sideslip range of + or - 20 degrees. In addition to tests of the basic configuration, component build-up tests were conducted; and the effects of power, forebody nose geometry, canard surfaces, fuselage strakes, and engines on the lower surface alone were also determined. Control power available from deflections of wing flaps and aftbody flaps was also investigated and found to be significantly increased during power-on conditions. Large yawing moments resulted from asymmetric flow fields exhibited by the forebody as revealed by both surface pressure data and flow visualization. Increasing nose bluntness reduced the yawing-moment asymmetry, and the addition of a canard eliminated the yawing-moment asymmetry.

  4. Analysis of some aerodynamic characteristics due to wing-jet interaction

    NASA Technical Reports Server (NTRS)

    Fillman, G. L.; Lan, C. E.

    1979-01-01

    The results of two separate theoretical investigations are presented. A program was used which is capable of predicting the aerodynamic characteristics of both upper-surface blowing (USB) and over-wing blowing (OWB) configurations. A theoretical analysis of the effects of over-wing blowing jets on the induced drag of a 50 deg sweep back wing was developed. Experiments showed net drag reductions associated with the well known lift enhancement due to over-wing blowing. The mechanisms through which this drag reduction is brought about are presented. Both jet entrainment and the so called wing-jet interaction play important roles in this process. The effects of a rectangular upper-surface blowing jet were examined for a wide variety of planforms. The isolated effects of wing taper, sweep, and aspect ratio variations on the incremental lift due to blowing are presented. The effects of wing taper ratio and sweep angle were found to be especially important parameters when considering the relative levels of incremental lift produced by an upper-surface blowing configuration.

  5. Investigation of Aerodynamic and Icing Characteristics of Recessed Fuel-Vent Configurations

    NASA Technical Reports Server (NTRS)

    Ruggeri, Robert S.; VonGlahn, Uwe H.; Rollins, Vern G.

    1949-01-01

    An investigation has been conducted in the NACA Cleveland icing research tunnel to determine the aerodynamic and icing characteristics of several recessed fuel-vent configurations. The vents were investigated aerodynamically to obtain vent-tube pressures and pressure distributions on the ramp surface as functions of tunnel-air velocity and angle of attack. Icing investigations were made to determine the vent-tube pressure losses for several icing conditions at tunnel-air velocities ranging from 220 to 440 feet per second. In general, under nonicing conditions, the configurations with diverging ramp walls maintained, vent-tube pressures greater than the required marginal value of 2 inches of water positive pressure differential between the fuel cell and the compartment containing the fuel cell for a range of angles of attack from 0 to 14deg at a tunnel-air velocity of approximately 240 feet per second. A configuration haying divergIng ramp sldewalls, a 7deg ramp angle; and vent tubes manifold,ed to a common plenum chamber opening through a slot In the ramp floor gave the greatest vent-tube pressures for all the configurations investigated. The use of the plenum chamber resulted in uniform pressures in all vent tubes. In a cloud-icing condition, roughness caused by ice formations on the airfoil surface ahead of the vent ramp, rather than icing of the vent configuration, caused a rapid loss in vent-tube pressures during the first few minutes of an icing period. Only the configuration having diverging ramp sidewalls, a 7 ramp angle, and a common plenum chamber maintained the required vent-tube pressures throughout a 60-minute icing period, although the ice formations on this configuration were more severe than those observed for the other configurations. No complete closure of vent-tube openings occurred for the configurations investigated. A simulated freezing-rain condition caused a greater and more rapid vent-tube pressure loss than was observed for a cloud

  6. Effects of spanwise nozzle geometry and location on the longitudinal aerodynamic characteristics of a vectored-engine-over-wing configuration at subsonic speeds

    NASA Technical Reports Server (NTRS)

    Leavitt, L. D.; Yip, L. P.

    1978-01-01

    A V/STOL tunnel study was performed to determine the effects of spanwise blowing on longitudinal aerodynamic characteristics of a model using a vectored-over-wing powered lift concept. The effects of spanwise nozzle throat area, internal and external nozzle geometry, and vertical and axial location were investigated. These effects were studied at a Mach number of 0.186 over an angle-of-attack range from 14 deg to 40 deg. A high pressure air system was used to provide jet-exhaust simulation. Engine nozzle pressure ratio was varied from 1.0 (jet off) to approximately 3.75.

  7. Modification of k-ω turbulence model for predicting airfoil aerodynamic performance

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Yan, Hao; Fang, Hong; Wang, Ming

    2015-06-01

    Predicting wind turbine S825 airfoil's aerodynamic performance is crucial to improving its energy efficiency and reducing its environmental impact. In this paper, a numerical simulation on the wind turbine S825 airfoil is conducted with k-ω turbulence model at different attack angles. By comparing with experimental data, a new method of modifying k-ω model is proposed. A modifying function is proposed to limit the production term in ω equation based on fluid rotation and deformation. This method improves turbulent viscosity and decreases separating region when the airfoil works at large separating conditions. The predictive accuracy could be improved by using the modified k-ω turbulence model.

  8. Cooled-turbine aerodynamic performance prediction from reduced primary to coolant total-temperature-ratio results

    NASA Technical Reports Server (NTRS)

    Goldman, L. J.

    1976-01-01

    The prediction of the cooled aerodynamic performance, for both stators and turbines, at actual primary to coolant inlet total temperature ratios from the results obtained at a reduced total temperature ratio is described. Theoretical and available experimental results were compared for convection film and transpiration cooled stator vanes and for a film cooled, single stage core turbine. For these tests the total temperature ratio varied from near 1.0 to about 2.7. The agreement between the theoretical and the experimental results was, in general, reasonable.

  9. Effect of Trailing Edge Flow Injection on Fan Noise and Aerodynamic Performance

    NASA Technical Reports Server (NTRS)

    Fite, E. Brian; Woodward, Richard P.; Podboy, Gary G.

    2006-01-01

    An experimental investigation using trailing edge blowing for reducing fan rotor/guide vane wake interaction noise was completed in the NASA Glenn 9- by 15-foot Low Speed Wind Tunnel. Data were acquired to measure noise, aerodynamic performance, and flow features for a 22" tip diameter fan representative of modern turbofan technology. The fan was designed to use trailing edge blowing to reduce the fan blade wake momentum deficit. The test objective was to quantify noise reductions, measure impacts on fan aerodynamic performance, and document the flow field using hot-film anemometry. Measurements concentrated on approach, cutback, and takeoff rotational speeds as those are the primary conditions of acoustic interest. Data are presented for a 2% (relative to overall fan flow) trailing edge injection rate and show a 2 dB reduction in Overall Sound Power Level (OAPWL) at all fan test speeds. The reduction in broadband noise is nearly constant and is approximately 1.5 dB up to 20 kHz at all fan speeds. Measurements of tone noise show significant variation, as evidenced by reductions of up to 6 dB in the 2 BPF tone at 6700 rpm.: and increases of nearly 2 dB for the 4 BPF tone at approach speed. Aerodynamic performance measurements show the fan with 2 % injection has an overall efficiency that is comparable to the baseline fan and operates, as intended, with nearly the same pressure ratio and mass flow parameters. Hot-film measurements obtained at the approach operating condition indicate that mean blade wake filling in the tip region was not as significant as expected. This suggests that additional acoustic benefits could be realized if the trailing edge blowing could be modified to provide better filling of the wake momentum deficit. Nevertheless, the hot-film measurements indicate that the trailing edge blowing provided significant reductions in blade wake turbulence. Overall, these results indicate that further work may be required to fully understand the proper

  10. Longitudinal Aerodynamic Characteristics of a Wing-Body-Tail Model Having a Highly Tapered, Cambered 45 degree Swept Wing of Aspect Ratio 4 at Transonic Speeds

    NASA Technical Reports Server (NTRS)

    West, F. E., Jr.

    1959-01-01

    The longitudinal aerodynamic characteristics of a wing-body-horizontal-tail configuration designed for efficient performance at transonic speeds has been investigated at Mach numbers from 0.80 to 1.03 in the Langley 16-foot transonic tunnel. The effect of adding an outboard leading-edge chord-extension to the highly tapered 45 deg. swept wing was also obtained. The average Reynolds number for this investigation was 6.7 x 10(exp 6) based on the wing mean aerodynamic chord. The relatively low tail placement as well as the addition of a chord-extension achieved some alleviation of the pitchup tendencies of the wing-fuselage configuration. The maximum trimmed lift-drag ratio was 16.5 up to a Mach number of 0.9, with the moment center located at the quarter-chord point of the mean aerodynamic chord. For the untrimmed case, the maximum lift-drag ratio was approximately 19.5 up to a Mach number of 0.9.

  11. Experimental Investigation of the Low-Speed Aerodynamic Characteristics of a 5.8-Percent Scale Hybrid Wing Body Configuration

    NASA Technical Reports Server (NTRS)

    Gatlin, Gregory M.; Vicroy, Dan D.; Carter, Melissa B.

    2012-01-01

    A low-speed experimental investigation has been conducted on a 5.8-percent scale Hybrid Wing Body configuration in the NASA Langley 14- by 22-Foot Subsonic Tunnel. This Hybrid Wing Body (HWB) configuration was designed with specific intention to support the NASA Environmentally Responsible Aviation (ERA) Project goals of reduced noise, emissions, and fuel burn. This HWB configuration incorporates twin, podded nacelles mounted on the vehicle upper surface between twin vertical tails. Low-speed aerodynamic characteristics were assessed through the acquisition of force and moment, surface pressure, and flow visualization data. Longitudinal and lateral-directional characteristics were investigated on this multi-component model. The effects of a drooped leading edge, longitudinal flow-through nacelle location, vertical tail shape and position, elevon deflection, and rudder deflection have been studied. The basic configuration aerodynamics, as well as the effects of these configuration variations, are presented in this paper.

  12. Aerodynamic characteristics of a high-wing transport configuration with a over-the-wing nacelle-pylon arrangement

    NASA Technical Reports Server (NTRS)

    Henderson, W. P.; Abeyounis, W. K.

    1985-01-01

    An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to determine the effects on the aerodynamic characteristics of a high-wing transport configuration of installing an over-the-wing nacelle-pylon arrangement. The tests are conducted at Mach numbers from 0.70 to 0.82 and at angles of attack from -2 deg to 4 deg. The configurational variables under study include symmetrical and contoured nacelles and pylons, pylon size, and wing leading-edge extensions. The symmetrical nacelles and pylons reduce the lift coefficient, increase the drag coefficient, and cause a nose-up pitching-moment coefficient. The contoured nacelles significantly reduce the interference drag, though it is still excessive. Increasing the pylon size reduces the drag, whereas adding wing leading-edge extension does not affect the aerodynamic characteristics significantly.

  13. Effects of thickness on the aerodynamic characteristics of an initial low-speed family of airfoils for general aviation applications

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Beasley, W. D.

    1976-01-01

    Wind tunnel tests were conducted to determine the effects of airfoil thickness-ratio on the low speed aerodynamic characteristics of an initial family of airfoils. The results were compared with theoretical predictions obtained from a subsonic viscous method. The tests were conducted over a Mach number range from 0.10 to 0.28. Chord Reynolds numbers varied from about 2.0 x 1 million to 9.0 x 1 million.

  14. Tests of Four Full-scale Propellers to Determine the Effect of Trailing-edge Extensions on Propeller Aerodynamic Characteristics

    NASA Technical Reports Server (NTRS)

    Maynard, Julian D.; Evans, Albert J

    1945-01-01

    Propellers with trailing-edge extensions were studied to determine aerodynamic characteristics. Trailing-edge extension increased power absorbed by propeller with little loss in efficiency. Power coefficient for maximum efficiency was greater for 20% camber type extension than for 20% straight type extension over range of advance ratio of 1.0 to 2.5 although camber type was less efficient. Efficiency was about the same for cruising and high-speed at a high power coefficient for propeller with extension.

  15. Longitudinal aerodynamics of a low-wing lift-fan transport including hover characteristics in and out of ground effect

    NASA Technical Reports Server (NTRS)

    Hoad, D. R.; Gentry, G. L., Jr.

    1975-01-01

    A wind-tunnel investigation was conducted in the Langley V/STOL tunnel to determine the longitudinal aerodynamic characteristics of a six-fan, tip-driven (remote) lift-fan VTOL transport throughout transition. The large midspan lift-fan pods and cruise fans were removed to determine their influence on the stability and control of the configuration. Data were obtained in the hovering mode for ranges of model height above ground. The data are presented without analysis or discussion.

  16. JT9D performance deterioration results from a simulated aerodynamic load test

    NASA Technical Reports Server (NTRS)

    Stakolich, E. G.; Stromberg, W. J.

    1981-01-01

    The results of testing to identify the effects of simulated aerodynamic flight loads on JT9D engine performance are presented. The test results were also used to refine previous analytical studies on the impact of aerodynamic flight loads on performance losses. To accomplish these objectives, a JT9D-7AH engine was assembled with average production clearances and new seals as well as extensive instrumentation to monitor engine performance, case temperatures, and blade tip clearance changes. A special loading device was designed and constructed to permit application of known moments and shear forces to the engine by the use of cables placed around the flight inlet. The test was conducted in the Pratt & Whitney Aircraft X-Ray Test Facility to permit the use of X-ray techniques in conjunction with laser blade tip proximity probes to monitor important engine clearance changes. Upon completion of the test program, the test engine was disassembled, and the condition of gas path parts and final clearances were documented. The test results indicate that the engine lost 1.1 percent in thrust specific fuel consumption (TSFC), as measured under sea level static conditions, due to increased operating clearances caused by simulated flight loads. This compares with 0.9 percent predicted by the analytical model and previous study efforts.

  17. An analysis for high speed propeller-nacelle aerodynamic performance prediction. Volume 1: Theory and application

    NASA Technical Reports Server (NTRS)

    Egolf, T. Alan; Anderson, Olof L.; Edwards, David E.; Landgrebe, Anton J.

    1988-01-01

    A computer program, the Propeller Nacelle Aerodynamic Performance Prediction Analysis (PANPER), was developed for the prediction and analysis of the performance and airflow of propeller-nacelle configurations operating over a forward speed range inclusive of high speed flight typical of recent propfan designs. A propeller lifting line, wake program was combined with a compressible, viscous center body interaction program, originally developed for diffusers, to compute the propeller-nacelle flow field, blade loading distribution, propeller performance, and the nacelle forebody pressure and viscous drag distributions. The computer analysis is applicable to single and coaxial counterrotating propellers. The blade geometries can include spanwise variations in sweep, droop, taper, thickness, and airfoil section type. In the coaxial mode of operation the analysis can treat both equal and unequal blade number and rotational speeds on the propeller disks. The nacelle portion of the analysis can treat both free air and tunnel wall configurations including wall bleed. The analysis was applied to many different sets of flight conditions using selected aerodynamic modeling options. The influence of different propeller nacelle-tunnel wall configurations was studied. Comparisons with available test data for both single and coaxial propeller configurations are presented along with a discussion of the results.

  18. Prediction of the hub vortex instability within wind turbine wakes and effects of the incoming wind and turbine aerodynamic characteristics

    NASA Astrophysics Data System (ADS)

    Iungo, Giacomo Valerio; Viola, Francesco; Camarri, Simone; Porté-Agel, Fernando; Gallaire, Francois

    2014-11-01

    Instability of the hub vortex, which is a vorticity structure present in wind turbine near-wake and mainly oriented along the streamwise direction, is predicted from wake velocity measurements. In this work, stability analysis is performed on wind tunnel velocity measurements acquired in the wake produced from a wind turbine model immersed in a uniform flow. Turbulence effects on wake dynamics are taken into account by modeling the Reynolds stresses through eddy-viscosity models, which are calibrated on the wind tunnel data. This formulation leads to the identification of one dominant mode associated with the hub vortex instability, which is characterized by a counter-winding single-helix mode. Moreover, this analysis also predicts accurately the frequency of the hub vortex instability observed experimentally. The hub vortex instability is also investigated by considering incoming wind fields with different turbulence characteristics, different turbine aerodynamic designs and operational regimes, which affect the morphology of the wake vorticity structures and their dynamics. The ultimate goal of this work consists in providing useful information for predicting wind turbine wake dynamics and their effects on downstream wake recovery, thus to maximize wind power harvesting.

  19. Analysis of wind tunnel test results for a 9.39-per cent scale model of a VSTOL fighter/attack aircraft. Volume 1: Study overview. [aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Lummus, J. R.; Joyce, G. T.; Omalley, C. D.

    1980-01-01

    The ability of current methodologies to accurately predict the aerodynamic characteristics identified as uncertainties was evaluated for two aircraft configurations. The two wind tunnel models studied horizontal altitude takeoff and landing V/STOL fighter aircraft derivatives.

  20. Improvement in Capsule Abort Performance Using Supersonic Aerodynamic Interaction by Fences

    NASA Astrophysics Data System (ADS)

    Koyama, Hiroto; Wang, Yunpeng; Ozawa, Hiroshi; Doi, Katsunori; Nakamura, Yoshiaki

    The space transportation system will need advanced abort systems to secure crew against serious accidents. Here this study deals with the capsule-type space transportation systems with a Launch Abort System (LAS). This system is composed of a conic capsule as a Launch Abort Vehicle (LAV) and a cylindrical rocket as a Service Module (SM), and the capsule is moved away from the rocket by supersonic aerodynamic interactions in an emergency. We propose a method to improve the performance of the LAV by installing fences at the edges of surfaces on the rocket and capsule sides. Their effects were investigated by experimental measurements and numerical simulations. Experimental results show that the fences on the rocket and capsule surfaces increase the aerodynamic thrust force on the capsule by 70% in a certain clearance between the capsule and rocket. Computational results show the detailed flow fields where the centripetal flow near the surface on the rocket side is induced by the fence on the rocket side and the centrifugal flow near the surface on the capsule side is blocked by the fence on the capsule side. These results can confirm favorable effects of the fences on the performance of the LAS.

  1. Unstructured Grid Euler Method Assessment for Longitudinal and Lateral/Directional Aerodynamic Performance Analysis of the HSR Technology Concept Airplane at Supersonic Cruise Speed

    NASA Technical Reports Server (NTRS)

    Ghaffari, Farhad

    1999-01-01

    Unstructured grid Euler computations, performed at supersonic cruise speed, are presented for a High Speed Civil Transport (HSCT) configuration, designated as the Technology Concept Airplane (TCA) within the High Speed Research (HSR) Program. The numerical results are obtained for the complete TCA cruise configuration which includes the wing, fuselage, empennage, diverters, and flow through nacelles at M (sub infinity) = 2.4 for a range of angles-of-attack and sideslip. Although all the present computations are performed for the complete TCA configuration, appropriate assumptions derived from the fundamental supersonic aerodynamic principles have been made to extract aerodynamic predictions to complement the experimental data obtained from a 1.675%-scaled truncated (aft fuselage/empennage components removed) TCA model. The validity of the computational results, derived from the latter assumptions, are thoroughly addressed and discussed in detail. The computed surface and off-surface flow characteristics are analyzed and the pressure coefficient contours on the wing lower surface are shown to correlate reasonably well with the available pressure sensitive paint results, particularly, for the complex flow structures around the nacelles. The predicted longitudinal and lateral/directional performance characteristics for the truncated TCA configuration are shown to correlate very well with the corresponding wind-tunnel data across the examined range of angles-of-attack and sideslip. The complementary computational results for the longitudinal and lateral/directional performance characteristics for the complete TCA configuration are also presented along with the aerodynamic effects due to empennage components. Results are also presented to assess the computational method performance, solution sensitivity to grid refinement, and solution convergence characteristics.

  2. Aerodynamics of the flying snake Chrysopelea paradisi: how a bluff body cross-sectional shape contributes to gliding performance.

    PubMed

    Holden, Daniel; Socha, John J; Cardwell, Nicholas D; Vlachos, Pavlos P

    2014-02-01

    A prominent feature of gliding flight in snakes of the genus Chrysopelea is the unique cross-sectional shape of the body, which acts as the lifting surface in the absence of wings. When gliding, the flying snake Chrysopelea paradisi morphs its circular cross-section into a triangular shape by splaying its ribs and flattening its body in the dorsoventral axis, forming a geometry with fore-aft symmetry and a thick profile. Here, we aimed to understand the aerodynamic properties of the snake's cross-sectional shape to determine its contribution to gliding at low Reynolds numbers. We used a straight physical model in a water tunnel to isolate the effects of 2D shape, analogously to studying the profile of an airfoil of a more typical flyer. Force measurements and time-resolved (TR) digital particle image velocimetry (DPIV) were used to determine lift and drag coefficients, wake dynamics and vortex-shedding characteristics of the shape across a behaviorally relevant range of Reynolds numbers and angles of attack. The snake's cross-sectional shape produced a maximum lift coefficient of 1.9 and maximum lift-to-drag ratio of 2.7, maintained increases in lift up to 35 deg, and exhibited two distinctly different vortex-shedding modes. Within the measured Reynolds number regime (Re=3000-15,000), this geometry generated significantly larger maximum lift coefficients than many other shapes including bluff bodies, thick airfoils, symmetric airfoils and circular arc airfoils. In addition, the snake's shape exhibited a gentle stall region that maintained relatively high lift production even up to the highest angle of attack tested (60 deg). Overall, the cross-sectional geometry of the flying snake demonstrated robust aerodynamic behavior by maintaining significant lift production and near-maximum lift-to-drag ratios over a wide range of parameters. These aerodynamic characteristics help to explain how the snake can glide at steep angles and over a wide range of angles of attack

  3. Investigation of Aerodynamic and Icing Characteristics of Water-Inertia-Separation Inlets for Turbojet Engines

    NASA Technical Reports Server (NTRS)

    VonGlahn, Uwe; Blatz, R. E.

    1950-01-01

    The results of an investigation of several internal water-inertia-separation inlets consisting of a main duct and an alternate duct designed to prevent automatically the entrance of large quantities of water into a turbojet engine in icing conditions are presented. Total-pressure losses and icing characteristics for a direct-ram inlet and the inertia-separation inlets are compared at similar aerodynamic and simulated icing conditions. Complete ice protection for inlet guide vanes could not be achieved with the inertia-separation inlets investigated. Approximately 8 percent of the volume of water entering the nacelles remained. In the air passing into the compressor inlet. Heavy alternate-duct-elbow ice formations caused by secondary inertia separation resulted in rapid total-pressure losses and decreases in mass flow. The duration in an icing condition for an inertia-separation- inlet, without local surface heating, was increased approximately four times above that for a direct-ram inlet with a compressor-inlet screen. For normal nonicing operation, the inertia-separation- inlet total-pressure losses were comparable to a direct-ram installation. The pressure losses and the circumferential uniformity of the mass flow in all the inlets were relatively independent of angle of attack. Use of an inertia-separation inlet would in most cases require a larger diameter nacelle than a direct-ram inlet in order to obtain an alternate duct sufficiently large to pass the required engine air flow at duct Mach numbers below 1.0 at the minimum area.

  4. Experimental Study on Aerodynamic Characteristics of a Stepped-Nose Obstacle

    NASA Astrophysics Data System (ADS)

    Cakrawala, Anang; Umemura, Akira

    Wind tunnel experiments were conducted to obtain a comprehensive understanding of the aerodynamic characteristics of two-dimensional stepped-nose obstacles. In our previous numerical study on the flow around stepped-nose obstacles at a zero angle of attack, the following favorable properties have been found for such step configuration that the flow separating from the front corners reattaches to the leading edges of the side surfaces. (1) The strong vortices trapped in the step region produce the suction forces acting on the step walls to cancel the drag force acting the front surface. (2) The suppression of large-scale flow separation on the obstacle’s sides reduces not only the suction force acting on the back surface, but also the lateral force fluctuation to a great degree. (3) The resulting net drag coefficient is much smaller than that of square/rectangular obstacles. In the present experimental study, the drag coefficient of stepped-nosed obstacles with various step height and length, at zero angle of attack, was measured to identify the optimum step configuration for large drag reduction. The effect of attack angle on drag, lift and moment coefficients was examined to gain insight into the static and dynamic stability of stepped-nose obstacles. The effect of step configuration on the Strouhal number was also examined. It was found that the stepped nose brought about static stability to the obstacle with a rather large step length-to-height ratio, but neither static nor dynamic stability was derived for the optimal step configuration with maximum drag reduction.

  5. Acoustic and aerodynamic performance of a 1.83 meter (6 foot) diameter 1.2 pressure ratio fan (QF-6). [for short takeoff aircraft

    NASA Technical Reports Server (NTRS)

    Woodward, R. P.; Lucas, J. G.; Stakolich, E. G.

    1974-01-01

    A 1.2-pressure-ratio, 1.83-meter-(6-ft-) diameter experimental fan stage with characteristics suitable for use in STOL aircraft engines was tested for acoustic and aerodynamic performance. The design incorporated features for low noise, including absence of inlet guide vanes, low rotor-blade-tip speed, low aerodynamic blade loading, and long axial spacing between the rotor and stator rows. The stage was run with four nozzles of different area. The perceived noise along a 152.4 meter (500-ft) sideline was rear-quadrant dominated with a maximum design-point level of 103.9 PNdb. The acoustic 1/3-octave results were analytically separated into broadband and pure-tone components. It was found that the stage noise levels generally increase with a decrease in nozzle area, with this increase observed primarily in the broadband noise component. A stall condition was documented acoustically with a 90-percent-of-design-area nozzle.

  6. Low-speed aerodynamic characteristics of a twin-engine general aviation configuration with aft-fuselage-mounted pusher propellers

    NASA Technical Reports Server (NTRS)

    Dunham, Dana Morris; Gentry, Garl L., Jr.; Manuel, Gregory S.; Applin, Zachary T.; Quinto, P. Frank

    1987-01-01

    An investigation was conducted to determine the aerodynamic characteristics of an advanced turboprop aircraft model with aft-pylon-mounted pusher propellers. Tests were conducted through an angle-of-attack range of -8 to 28 degrees, and an angle-of-sideslip range of -20 to 20 degrees at free-stream conditions corresponding to Reynolds numbers of 0.55 to 2.14 x 10 to the 6th power based on mean aerodynamic chord. Test results show that for the unpowered configurations the maximum lift coefficients for the cruise, takeoff, and landing configurations are 1.45, 1.90, and 2.10, respectively. Nacelle installation results in a drag coefficient increase of 0.01. Increasing propeller thrust results in a significant increase in lift for angles of attack above stall and improves the longitudinal stability. The cruise configuration remains longitudinally stable to an angle of attack 5 degrees beyond the stall angle, the takeoff configuration is stable 4 degrees beyond stall angle, and the landing configuration is stable 3 degrees beyond stall angle. The predominant effect of symmetric thrust on the lateral-directional aerodynamic characteristics is in the post-stall region, where additional rudder control is available with power on.

  7. Hydrodynamic and Aerodynamic Characteristics of a Model of a Supersonic Multijet Water-Based Aircraft Equipped with Supercavitating Hydrofoils

    NASA Technical Reports Server (NTRS)

    McKann, Robert E.; Blanchard, Ulysse J.; Pearson, Albin O.

    1960-01-01

    The hydrodynamic and aerodynamic characteristics of a model of a multijet water-based Mach 2.0 aircraft equipped with hydrofoils have been determined. Takeoff stability and spray characteristics were very good, and sufficient excess thrust was available for takeoff in approximately 32 seconds and 4,700 feet at a gross weight of 225,000 pounds. Longitudinal and lateral stability during smooth-water landings were good. Lateral stability was good during rough-water landings, but forward location of the hydrofoils or added pitch damping was required to prevent diving. Hydrofoils were found to increase the aerodynamic lift-curve slope and to increase the aerodynamic drag coefficient in the transonic speed range, and the maximum lift-drag ratio decreased from 7.6 to 7.2 at the cruise Mach number of 0.9. The hydrofoils provided an increment of positive pitching moment over the Mach number range of the tests (0.6 to 1.42) and reduced the effective dihedral and directional stability.

  8. Aerodynamic characteristics of a canard-controlled missile at Mach numbers of 1.5 and 2.0.

    NASA Technical Reports Server (NTRS)

    Kassner, D. L.; Wettlaufer, B.

    1977-01-01

    A typical missile model with nose mounted canards and cruciform tail surfaces was tested in the Ames 6- by 6-Foot Wind Tunnel to determine the contributions of the component aerodynamic surfaces to the static aerodynamic characteristics at Mach numbers of 1.5 and 2.0 and Reynolds number of 1 million based on body diameter. Data were obtained at angles of attack ranging from -3 deg to 12 deg for various stages of model build-up (i.e., with and without canard and/or tail surfaces). Results were obtained both with the model unrolled and rolled 45 deg. For the canard and tail arrangements investigated, the model was trimmable at angles of attack up to about 10 deg with canard deflections of 9 deg. Also, the tail arrangements studied provided ample pitch stability. there were no appreciable effects of model roll orientation.

  9. Advanced Aerodynamic Devices to Improve the Performance, Economics, Handling, and Safety of Heavy Vehicles

    SciTech Connect

    Robert J. Englar

    2001-05-14

    Research is being conducted at the Georgia Tech Research Institute (GTRI) to develop advanced aerodynamic devices to improve the performance, economics, stability, handling and safety of operation of Heavy Vehicles by using previously-developed and flight-tested pneumatic (blown) aircraft technology. Recent wind-tunnel investigations of a generic Heavy Vehicle model with blowing slots on both the leading and trailing edges of the trailer have been conducted under contract to the DOE Office of Heavy Vehicle Technologies. These experimental results show overall aerodynamic drag reductions on the Pneumatic Heavy Vehicle of 50% using only 1 psig blowing pressure in the plenums, and over 80% drag reductions if additional blowing air were available. Additionally, an increase in drag force for braking was confirmed by blowing different slots. Lift coefficient was increased for rolling resistance reduction by blowing only the top slot, while downforce was produced for traction increase by blowing only the bottom. Also, side force and yawing moment were generated on either side of the vehicle, and directional stability was restored by blowing the appropriate side slot. These experimental results and the predicted full-scale payoffs are presented in this paper, as is a discussion of additional applications to conventional commercial autos, buses, motor homes, and Sport Utility Vehicles.

  10. The aerodynamic design and performance of the NASA/GE E3 low pressure turbine

    NASA Technical Reports Server (NTRS)

    Cherry, D. G.; Dengler, R. P.

    1984-01-01

    The aerodynamic design and scaled rig test results of the low pressure turbine (LPT) component for the NASA/General Electric Energy Efficient Engine (E3) are presented. The low pressure turbine is a highly loaded five-stage design featuring high outer wall slope, controlled vortex aerodynamics, low stage flow coefficient, and reduced clearances. An assessment of its performance has been made based on a series of scaled air turbine tests which were divided into two phases: Block I (March through August, 1979) and Block II (June through September, 1981). Results from the Block II five-stage test, summarized in the paper, indicate that the E3 LPT will attain an efficiency level of 91.5 percent at the Mach 0.8/35,000 ft. max. climb altitude design point. This is relative to program goals of 91.1 percent for the E3 demonstrator engine and 91.7 percent for a fully developed flight propulsion system LPT.

  11. Summary of shuttle data processing and aerodynamic performance comparisons for the first 11 flights

    NASA Technical Reports Server (NTRS)

    Findlay, J. T.; Kelly, G. M.; Heck, M. L.; Mcconnell, J. G.

    1984-01-01

    NASA Space Shuttle aerodynamic and aerothermodynamic research is but one part of the most comprehensive end-to-end flight test program ever undertaken considering: the extensive pre-flight experimental data base development; the multitude of spacecraft and remote measurements taken during entry flight; the complexity of the Orbiter aerodynamic configuration; the variety of flight conditions available across the entire speed regime; and the efforts devoted to flight data reduction throughout the aerospace community. Shuttle entry flights provide a wealth of research quality data, in essence a veritable flying wind tunnel, for use by researchers to verify and improve the operational capability of the Orbiter and provide data for evaluations of experimental facilities as well as computational methods. This final report merely summarizes the major activities conducted by the AMA, Inc. under NASA Contract NAS1-16087 as part of that interesting research. Investigators desiring more detailed information can refer to the glossary of AMA publications attached herein as Appendix A. Section I provides background discussion of software and methodology development to enable Best Estimate Trajectory (BET) generation. Actual products generated are summarized in Section II as tables which completely describe the post-flight products available from the first three-year Shuttle flight history. Summary results are presented in Section III, with longitudinal performance comparisons included as Appendices for each of the flights.

  12. Study of aerodynamic technology for single-cruise-engine V/STOL fighter/attack aircraft

    NASA Technical Reports Server (NTRS)

    Hess, J. R.; Bear, R. L.

    1982-01-01

    A viable, single engine, supersonic V/STOL fighter/attack aircraft concept was defined. This vectored thrust, canard wing configuration utilizes an advanced technology separated flow engine with fan stream burning. The aerodynamic characteristics of this configuration were estimated and performance evaluated. Significant aerodynamic and aerodynamic propulsion interaction uncertainties requiring additional investigation were identified. A wind tunnel model concept and test program to resolve these uncertainties and validate the aerodynamic prediction methods were defined.

  13. Navier-Stokes simulations of Orbiter aerodynamic characteristics including pitch trim and bodyflap

    NASA Technical Reports Server (NTRS)

    Weilmuenster, K. James; Gnoffo, Peter A.; Greene, Francis A.

    1994-01-01

    An analysis of the longitudinal aerodynamics of the shuttle orbiter in the hypersonic flight regime is made through the use of computational fluid dynamics. Particular attention is given to establishing the cause of the 'pitching moment anomaly,' which occurred on the orbiter's first flight, and to computing the aerodynamics of a complete orbiter configuration at flight conditions. Data from ground-based facilities as well as orbiter flight data are used to validate the computed results. Analysis shows that the pitching moment anomaly is a real-gas chemistry effect that was not simulated in ground-based facilities, which used air as a test gas. Computed flight aerodynamics for the orbiter are within 5% of the measured flight values and trim bodyflap deflections are predicted to within 10%.

  14. Performance deterioration based on simulated aerodynamic loads test, JT9D jet engine diagnostics program

    NASA Technical Reports Server (NTRS)

    Stromberg, W. J.

    1981-01-01

    An engine was specially prepared with extensive instrumentation to monitor performance, case temperatures, and clearance changes. A special loading device was used to apply known loads on the engine by the use of cables placed around the flight inlet. These loads simulated the estimated aerodynamic pressure distributions that occur on the inlet in various segments of a typical airplane flight. Test results indicate that the engine lost 1.3 percent in take-off thrust specific fuel consumption (TSFC) during the course of the test effort. Permanent clearance changes due to the loads accounted for 1.1 percent; increase in low pressure compressor airfoil roughness and thermal distortion in the high pressure turbine accounted for 0.2 percent. Pretest predicted performance loss due to clearance changes was 0.9 percent in TSFC. Therefore, the agreement between measurement and prediction is considered to be excellent.

  15. Effects of aerodynamic interaction between main and tail rotors on helicopter hover performance and noise

    NASA Technical Reports Server (NTRS)

    Menger, R. P.; Wood, T. L.; Brieger, J. T.

    1983-01-01

    A model test was conducted to determine the effects of aerodynamic interaction between main rotor, tail rotor, and vertical fin on helicopter performance and noise in hover out of ground effect. The experimental data were obtained from hover tests performed with a .151 scale Model 222 main rotor, tail rotor and vertical fin. Of primary interest was the effect of location of the tail rotor with respect to the main rotor. Penalties on main rotor power due to interaction with the tail rotor ranged up to 3% depending upon tail rotor location and orientation. Penalties on tail rotor power due to fin blockage alone ranged up to 10% for pusher tail rotors and up to 50% for tractor tail rotors. The main rotor wake had only a second order effect on these tail rotor/fin interactions. Design charts are presented showing the penalties on main rotor power as a function of the relative location of the tail rotor.

  16. Aerodynamic performance of a 1.25-pressure-ratio axial-flow fan stage

    NASA Technical Reports Server (NTRS)

    Moore, R. D.; Steinke, R. J.

    1974-01-01

    Aerodynamic design parameters and overall and blade-element performances of a 1.25-pressure-ratio fan stage are reported. Detailed radial surveys were made over the stable operating flow range at rotative speeds from 70 to 120 percent of design speed. At design speed, the measured stage peak efficiency of 0.872 occurred at a weight flow of 34.92 kilograms per second and a pressure ratio of 1.242. Stage stall margin is about 20 percent based on the peak efficiency and stall conditions. The overall peak efficiency for the rotor was 0.911. The overall stage performance showed no significant change when the stators were positioned at 1, 2, or 4 chords downstream of the rotor.

  17. Longitudinal aerodynamic characteristics of a low-wing lift-fan transport including hover characteristics in and out of ground effect

    NASA Technical Reports Server (NTRS)

    Hoad, D. R.; Gentry, G. L., Jr.

    1977-01-01

    The longitudinal aerodynamic characteristics of a six-fan, tip-driven (remote) lift-fan VTOL transport through transition were determined by an investigation conducted in the Langley V/STOL tunnel. Tests were also made with the large midspan lift-fan pods and lift-cruise fans removed to determine their their influence on the stability and control of the configuration. Data were obtained for a range of model height above ground.

  18. Effects of Shrouded Stator Cavity Flows on Multistage Axial Compressor Aerodynamic Performance

    NASA Technical Reports Server (NTRS)

    Wellborn, Steven R.; Okiishi, Theodore H.

    1996-01-01

    Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Data collected enabled differences in overall individual stage and the third stage blade element performance parameters to be compared. The results show conclusively that seal-tooth leakage ran have a large impact on compressor aerodynamic performance while the presence of the shrouded stator cavities alone seemed to have little influence. Overall performance data revealed that for every 1% increase in the seal-tooth clearance to blade-height ratio the pressure rise dropped up to 3% while efficiency was reduced by 1 to 1.5 points. These observed efficiency penalty slopes are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. Therefore, it appears that in order to correctly predict overall performance it is equally important to account for the effects of seal-tooth leakage as it is to include the influence of tip clearance flows. Third stage blade element performance data suggested that the performance degradation observed when leakage was increased was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near hub performance of the stator row in which leakage occurred. Second, the altered stator exit now conditions caused by increased leakage impaired the performance of the next downstream stage by decreasing the work input of the downstream rotor and increasing total pressure loss of the downstream stator. These trends caused downstream stages to progressively perform worse. Other measurements were acquired to determine spatial and temporal flow field variations within the up-and-downstream shrouded stator cavities. Flow within the cavities involved low momentum fluid traveling primarily

  19. Combined experimental and numerical investigations on the roughness effects on the aerodynamic performances of LPT blades

    NASA Astrophysics Data System (ADS)

    Berrino, Marco; Bigoni, Fabio; Simoni, Daniele; Giovannini, Matteo; Marconcini, Michele; Pacciani, Roberto; Bertini, Francesco

    2016-02-01

    The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels (Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers (300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters, further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested (Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.

  20. Acoustic and aerodynamic performance of a 1.83-meter (6-ft) diameter 1.25-pressure-ratio fan (QF-8)

    NASA Technical Reports Server (NTRS)

    Woodward, R. P.; Lucas, J. G.

    1976-01-01

    A 1.25-pressure-ratio 1.83-meter (6-ft) tip diameter experimental fan stage with characteristics suitable for engine application on STOL aircraft was tested for acoustic and aerodynamic performance. The design incorporated proven features for low noise, including absence of inlet guide vanes, low rotor blade tip speed, low aerodynamic blade loading, and long axial spacing between the rotor and stator blade rows. The fan was operated with five exhaust nozzle areas. The stage noise levels generally increased with a decrease in nozzle area. Separation of the acoustic one-third octave results into broadband and pure-tone components showed the broadband noise to be greater than the corresponding pure-tone components. The sideline perceived noise was highest in the rear quadrants. The acoustic results of QF-8 were compared with those of two similar STOL application fans in the test series. The QF-8 had somewhat higher relative noise levels than those of the other two fans. The aerodynamic results of QF-8 and the other two fans were compared with corresponding results from 50.8-cm (20-in.) diam scale models of these fans and design values. Although the results for the full-scale and scale models of the other two fans were in reasonable agreement for each design, the full-scale fan QF-8 results showed poor performance compared with corresponding model results and design expectations. Facility effects of the full-scale fan QF-8 installation were considered in analyzing this discrepancy.

  1. CF6 Jet Engine Performance Improvement Program: High Pressure Turbine Aerodynamic Performance Improvement

    NASA Technical Reports Server (NTRS)

    Fasching, W. A.

    1980-01-01

    The improved single shank high pressure turbine design was evaluated in component tests consisting of performance, heat transfer and mechanical tests, and in core engine tests. The instrumented core engine test verified the thermal, mechanical, and aeromechanical characteristics of the improved turbine design. An endurance test subjected the improved single shank turbine to 1000 simulated flight cycles, the equivalent of approximately 3000 hours of typical airline service. Initial back-to-back engine tests demonstrated an improvement in cruise sfc of 1.3% and a reduction in exhaust gas temperature of 10 C. An additional improvement of 0.3% in cruise sfc and 6 C in EGT is projected for long service engines.

  2. Aerodynamic performance of two fifteen-percent-scale wind-tunnel drive fan designs

    NASA Technical Reports Server (NTRS)

    Signor, D. B.; Borst, H. V.

    1986-01-01

    An experimental and analytical investigation of two fan blade designs was conducted. The fan blades tested were 15 percent scale models of the blades used in the National Full Scale Aerodynamic Complex fan drive at NASA Ames Research Center. The fan blades were composed of NACA-65 and modified NACA-65-series airfoil design sections. The blades with modified 65-series sections incorporated increased thickness on the upper surface, between the leading edge and the one-half chord position. Twist and taper were the same for both blade designs. The fan blades with modified 65-series sections were found to have an increase in stall margin when they were compared with the unmodified blades. The experimental performance data agreed favorably with theoretical calculations.

  3. A computer program for wing subsonic aerodynamic performance estimates including attainable thrust and vortex lift effects

    NASA Technical Reports Server (NTRS)

    Carlson, H. W.; Walkley, K. B.

    1982-01-01

    Numerical methods incorporated into a computer program to provide estimates of the subsonic aerodynamic performance of twisted and cambered wings of arbitrary planform with attainable thrust and vortex lift considerations are described. The computational system is based on a linearized theory lifting surface solution which provides a spanwise distribution of theoretical leading edge thrust in addition to the surface distribution of perturbation velocities. The approach used relies on a solution by iteration. The method also features a superposition of independent solutions for a cambered and twisted wing and a flat wing of the same planform to provide, at little additional expense, results for a large number of angles of attack or lift coefficients. A previously developed method is employed to assess the portion of the theoretical thrust actually attainable and the portion that is felt as a vortex normal force.

  4. Effects of aerodynamic heating and TPS thermal performance uncertainties on the Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.; Derry, S. M.; Maraia, R. J.

    1980-01-01

    A procedure for estimating uncertainties in the aerodynamic-heating and thermal protection system (TPS) thermal-performance methodologies developed for the Shuttle Orbiter is presented. This procedure is used in predicting uncertainty bands around expected or nominal TPS thermal responses for the Orbiter during entry. Individual flowfield and TPS parameters that make major contributions to these uncertainty bands are identified and, by statistical considerations, combined in a manner suitable for making engineering estimates of the TPS thermal confidence intervals and temperature margins relative to design limits. Thus, for a fixed TPS design, entry trajectories for future Orbiter missions can be shaped subject to both the thermal-margin and confidence-interval requirements. This procedure is illustrated by assessing the thermal margins offered by selected areas of the existing Orbiter TPS design for an entry trajectory typifying early flight test missions.

  5. Aerodynamic Stability and Performance of Next-Generation Parachutes for Mars Descent

    NASA Technical Reports Server (NTRS)

    Gonyea, Keir C.; Tanner, Christopher L.; Clark, Ian G.; Kushner, Laura K.; Schairer, Edward T.; Braun, Robert D.

    2013-01-01

    The Low Density Supersonic Decelerator Project is developing a next-generation supersonic parachute for use on future Mars missions. In order to determine the new parachute configuration, a wind tunnel test was conducted at the National Full-scale Aerodynamics Complex 80- by 120-foot Wind Tunnel at the NASA Ames Research Center. The goal of the wind tunnel test was to quantitatively determine the aerodynamic stability and performance of various canopy configurations in order to help select the design to be flown on the Supersonic Flight Dynamics tests. Parachute configurations included the diskgap- band, ringsail, and ringsail-variant designs referred to as a disksail and starsail. During the wind tunnel test, digital cameras captured synchronized image streams of the parachute from three directions. Stereo hotogrammetric processing was performed on the image data to track the position of the vent of the canopy throughout each run. The position data were processed to determine the geometric angular history of the parachute, which were then used to calculate the total angle of attack and its derivatives at each instant in time. Static and dynamic moment coefficients were extracted from these data using a parameter estimation method involving the one-dimensional equation of motion for a rotation of parachute. The coefficients were calculated over all of the available canopy states to reconstruct moment coefficient curves as a function of total angle of attack. From the stability curves, useful metrics such as the trim total angle of attack and pitch stiffness at the trim angle could be determined. These stability metrics were assessed in the context of the parachute's drag load and geometric porosity. While there was generally an inverse relationship between the drag load and the stability of the canopy, the data showed that it was possible to obtain similar stability properties as the disk-gap-band with slightly higher drag loads by appropriately tailoring the

  6. Performance and aerodynamic braking of a horizontal-axis wind turbine from small-scale wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Cao, H. V.; Wentz, W. H., Jr.

    1987-01-01

    Wind tunnel tests of three 20" diameter, zero twist, zero pitch wind turbine rotor models were conducted in a 7' x 10' wind tunnel to determine the performance of such rotors with NACA 23024 and NACA 64 sub 3-621 airfoil sections. Aerodynamic braking characteristics of a 38% span, 30% chord, vented aileron configuration were measured on the NACA 23024 rotor. Surface flow patterns were observed using fluorescent mini-tufts attached to the suction side of the rotor blades. Experimental results with and without ailerons are compared to predictions using airfoil section data and a momentum performance code. Results of the performance studies show that the 64 sub 3-621 rotor produces higher peak power than the 23024 rotor for a given rotor speed. Analytical studies, however, indicate that the 23024 should produce higher power. Transition strip experiments show that the 23024 rotor is much more sensitive to roughness than the 64 sub 3-621 rotor. These trends agree with analytical predictions. Results of the aileron test show that this aileron, when deflected, produces a braking torque at all tip speed ratios. In free wheeling coastdowns the rotor blade stopped, then rotated backward at a tip speed ratio of -0.6.

  7. Performance of an aerodynamic yaw controller mounted on the space shuttle orbiter body flap at Mach 10

    NASA Technical Reports Server (NTRS)

    Scallion, W. I.

    1995-01-01

    A wind-tunnel investigation of the effectiveness of an aerodynamic yaw controller mounted on the lower surface of a shuttle orbiter model body flap was conducted in the Langley 31-Inch Mach 10 Tunnel. The controller consisted of a 60 deg delta fin mounted perpendicular to the body flap lower surface and yawed 30 deg to the free stream direction. The control was tested at angles of attack from 20 deg to 40 deg at zero sideslip for a Reynolds number based on wing mean aerodynamic chord of 0.66 x 10(exp 6). The aerodynamic and control effectiveness characteristics are presented along with an analysis of the effectiveness of the controller in making a bank maneuver for Mach 18 flight conditions. The controller was effective in yaw and produced a favorable rolling moment. The analysis showed that the controller was as effective as the reaction control system in making the bank maneuver. These results warrant further studies of the aerodynamic/aerothermodynamic characteristics of the control concept for application to future transportation vehicles.

  8. Aerodynamics as a subway design parameter

    NASA Technical Reports Server (NTRS)

    Kurtz, D. W.

    1976-01-01

    A parametric sensitivity study has been performed on the system operational energy requirement in order to guide subway design strategy. Aerodynamics can play a dominant or trivial role, depending upon the system characteristics. Optimization of the aerodynamic parameters may not minimize the total operational energy. Isolation of the station box from the tunnel and reduction of the inertial power requirements pay the largest dividends in terms of the operational energy requirement.

  9. Transonic aerodynamic characteristics associated with variations in the geometry of the forward portion of irregular planform wings

    NASA Technical Reports Server (NTRS)

    Spencer, B., Jr.; Stone, D. R.

    1973-01-01

    The experimental aerodynamic characteristics of three basic wing planforms on a conceptual orbiter fuselage (designated the LO-100) have been obtained in the 8-Foot Transonic Pressure Tunnel. The study included variations in the forward portion (fillet) of each basic wing. Fillet sweeps to 78 deg were investigated while holding the spanwise intersection of the fillet and wing constant. The data were obtained at Mach numbers of 0.35 to 1.2 and at Reynolds number (depending on Mach number) of 1.9 million to 2.11 million per foot. The angle of attack was varied from about minus 2 deg to 22 deg at 0 deg of sideslip.

  10. Longitudinal aerodynamic and propulsion characteristics of a propulsive-wing V/STOL model at high subsonic speeds

    NASA Technical Reports Server (NTRS)

    Salters, L. B., Jr.; Schmeer, J. W.

    1973-01-01

    The aerodynamic and propulsion characteristics of a 1/6-scale propulsive-wing V/STOL air-powered model was investigated over the Mach number range from 0.40 to 0.96 and at angles of attack from -5 deg to 15 deg for several fan rotational speeds. Three fanduct-exit configurations were tested, including two exit areas. The model with 25-percent-thick wing had a drag-rise Mach number of 0.85, which is typical of aircraft with thinner, conventional, unswept wings.

  11. Aerodynamic Characteristics of a Model of an Inflatable-Sphere Launching Vehicle under Simulated Conditions of Mach Number and Altitude

    NASA Technical Reports Server (NTRS)

    Robinson, Ross B.; Morris, Odell A.

    1960-01-01

    An investigation has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel to determine the aerodynamic characteristics in pitch of a two-stage-rocket model configuration which simulated the last two stages of the launching vehicle for an inflatable sphere. Tests were made through an angle-of-attack range from -6 deg to 18 deg at dynamic pressures of 102 and 255 pounds per square foot with corresponding Mach numbers of 1.89 and 1.98 for the model both with and without a bumper arrangement designed to protect the rocket casing from the outer shell of the vehicle.

  12. Aerodynamic Characteristics at High Speeds of Related Full-Scale Propellers Having Different Blade-Section Cambers

    NASA Technical Reports Server (NTRS)

    Maynard, Julian D; Salters, Leland B , Jr

    1957-01-01

    Wind-tunnel tests of a full-scale two-blade NACA 10-(10)(08)-03 (high camber) propeller have been made for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. The results of these tests have been compared with results from previous tests of the NACA 10-(3) (08)-03 (low camber) and NACA 10-(5)(08)-03 (medium camber) propellers to evaluate the effects of blade-section camber on propeller aerodynamic characteristics.

  13. Aerodynamic Characteristics of a Slender Cone-cylinder Body of Revolution at a Mach Number of 3.85

    NASA Technical Reports Server (NTRS)

    Jack, John R

    1951-01-01

    An experimental investigation of the aerodynamics of a slender cone-cylinder body of revolution was conducted at a Mach number of 3.85 for angles of attack of 0 degree to 10 degrees and a Reynolds number of 3.85x10(exp 6). Boundary-layer measurements at zero angle of attack are compared with the compressible-flow formulations for predicting laminar boundary-layer characteristics. Comparison of experimental pressure and force values with theoretical values showed relatively good agreement for small angles of attack. The measured mean skin-friction coefficients agreed well with theoretical values obtained for laminar flow over cones.

  14. Aerodynamic characteristics of two single-stage-to-orbit vehicles at Mach 20.3

    NASA Technical Reports Server (NTRS)

    Bernot, P. T.

    1977-01-01

    The hypersonic stability, control, and performance characteristics of two configurations have been determined. Each configuration had a 50 deg swept delta wing, a vertical tail, and a body flap. One model represented a control configured vehicle with a reduced level of longitudinal static stability; the other model was designed for a conventional level of stability. Data were obtained over an angle of attack range of 0 deg to 50 deg and included effects of component buildup. In addition, the effects of the vertical tail on the lateral directional characteristics were obtained.

  15. Aerodynamic Characteristics of an Aerospace Vehicle During a Subsonic Pitch-Over Maneuver

    NASA Technical Reports Server (NTRS)

    Kleb, William L.

    1996-01-01

    Time-dependent CFD has been used to predict aerospace vehicle aerodynamics during a subsonic rotation maneuver. The inviscid 3D3U code is employed to solve the 3-D unsteady flow field using an unstructured grid of tetrahedra. As this application represents a challenge to time-dependent CFD, observations concerning spatial and temporal resolution are included. It is shown that even for a benign rotation rate, unsteady aerodynamic effects are significant during the maneuver. Possibly more significant, however, the rotation maneuver creates ow asymmetries leading to yawing moment, rolling moment, and side force which are not present in the quasi-steady case. A series of steady solutions at discrete points in the maneuver are also computed for comparison with wind tunnel measurements and as a means of quantifying unsteady effects.

  16. Modeling of aircraft unsteady aerodynamic characteristics. Part 2: Parameters estimated from wind tunnel data

    NASA Technical Reports Server (NTRS)

    Klein, Vladislav; Noderer, Keith D.

    1995-01-01

    Aerodynamic equations with unsteady effects were formulated for an aircraft in one-degree-of-freedom, small-amplitude, harmonic motion. These equations were used as a model for aerodynamic parameter estimation from wind tunnel oscillatory data. The estimation algorithm was based on nonlinear least squares and was applied in three examples to the oscillatory data in pitch and roll of 70 deg triangular wing and an X-31 model, and in-sideslip oscillatory data of the High Incidence Research Model 2 (HIRM 2). All three examples indicated that a model using a simple indicial function can explain unsteady effects observed in measured data. The accuracy of the estimated parameters and model verification were strongly influenced by the number of data points with respect to the number of unknown parameters.

  17. Plasma Influence on Characteristics of Aerodynamic Friction and Separation Flow Location

    DTIC Science & Technology

    2007-11-02

    Mirror- galvanometer oscillograph NO43.1 (6); • · Shadow Schlieren device IAB-451 (7-10). After a modernization the oscilloscope “Tektronix TDS...amplifier is transmitted to the mirror- galvanometer oscillograph (6), which in turn records the pressure variation diagram on a Plasma Aerodynamics...balance (4) is used, the signal from which is also transmitted to the 8-ANCh amplifier and then to the mirror- galvanometer oscillograph and is

  18. Experimental Hypersonic Aerodynamic Characteristics of the Space Shuttle Orbiter for a Range of Damage Scenarios

    NASA Technical Reports Server (NTRS)

    Brauckman, Gregory J.; Scallion, William I.

    2003-01-01

    Aerodynamic tests in support of the Columbia accident investigation were conducted in two hypersonic wind tunnels at the NASA Langley Research Center, the 20-Inch Mach 6 Air Tunnel and the 20-Inch Mach 6 CF4 Tunnel. The primary purpose of these tests was to measure the forces and moments generated by a variety of outer mold line alterations (damage scenarios) using 0.0075-scale models of the Space Shuttle Orbiter (approximately 10 inches in length). Simultaneously acquired global heat transfer mappings were obtained for a majority of the configurations tested. Test parameters include angles of attack from 38 to 42 deg, unit Reynolds numbers from 0.26 to 3.0 x10^6 per foot, and normal shock density ratios of 5 (Mach 6 air) and 12 (Mach 6 CF4). The damage scenarios evaluated included asymmetric boundary layer transition, gouges in the windward surface acreage thermal protection system tiles, wing leading edge damage (partially and fully missing reinforced carbon-carbon (RCC) panels), holes through the wing from the windward surface to the leeside, deformation of the wing windward surface, and main landing gear door and/or gear deployment. The aerodynamic data were compared to the magnitudes and directions observed in flight, and the heating images were evaluated in terms of the location of the generated disturbances and how these disturbance might relate to the response of discrete gages on the Columbia Orbiter vehicle during entry. The measured aerodynamic increments were generally small in magnitude, as were the flight-derived values during most of the entry. Asymmetric boundary layer transition (ABLT) results were consistent with the flight-derived Shuttle ABLT model, but not with the observed flight trends for STS-107. The partially missing leading edge panel results best matched both the early aerodynamic and heating trends observed in flight. A progressive damage scenario is presented that qualitatively matches the flight observations for the full entry.

  19. Aerodynamic and Flight Dynamic Characteristics of the New Family of 5. 56mm NATO Ammunition

    DTIC Science & Technology

    1985-10-01

    5 LIST OF TABLES .... 7 I. INTRODUCTION ........... ......, 9..,,.......,,.,.., .-. IeI TEST MATERIEL AND PROCEDURE...transonic and subsonic speeds. All Phase II aeroballistic tests were fired in the BRL Aerodynamics Range, using the same Phase I weapon mounting...shown in Figure 1. - The Phase III testing also used the weapon mounting system of Figure 1, but with the gun moved to one of the three firing positions

  20. Longitudinal Aerodynamic Characteristics to Large Angles of Attack of a Cruciform Missile Configuration at a Mach Number of 2

    NASA Technical Reports Server (NTRS)

    Spahr, J. R.

    1954-01-01

    The lift, pitching-moment, and drag characteristics of a missile configuration having a body of fineness ratio 9.33 and a cruciform triangular wing and tail of aspect ratio 4 were measured at a Mach number of 1.99 and a Reynolds number of 6.0 million, based on the body length. The tests were performed through an angle-of-attack range of -5 deg to 28 deg to investigate the effects on the aerodynamic characteristics of roll angle, wing-tail interdigitation, wing deflection, and interference among the components (body, wing, and tail). Theoretical lift and moment characteristics of the configuration and its components were calculated by the use of existing theoretical methods which have been modified for application to high angles of attack, and these characteristics are compared with experiment. The lift and drag characteristics of all combinations of the body, wing, and tail were independent of roll angle throughout the angle-of-attack range. The pitching-moment characteristics of the body-wing and body-wing-tail combinations, however, were influenced significantly by the roll angle at large angles of attack (greater than 10 deg). A roll from 0 deg (one pair of wing panels horizontal) to 45 deg caused a forward shift in the center of pressure which was of the same magnitude for both of these combinations, indicating that this shift originated from body-wing interference effects. A favorable lift-interference effect (lift of the combination greater than the sum of the lifts of the components) and a rearward shift in the center of pressure from a position corresponding to that for the components occurred at small angles of attack when the body was combined with either the exposed wing or tail surfaces. These lift and center-of-pressure interference effects were gradually reduced to zero as the angle of attack was increased to large values. The effect of wing-tail interference, which influenced primarily the pitching-moment characteristics, is dependent on the distance

  1. Longitudinal Aerodynamic Characteristics to Large Angles of Attack of a Cruciform Missile Configuration at a Mach Number of 2

    NASA Technical Reports Server (NTRS)

    Spahr, J Richard

    1954-01-01

    The lift, pitching-moment, and drag characteristics of a missile configuration having a body of fineness ratio 9.33 and a cruciform triangular wing and tail of aspect ratio 4 were measured at a Mach number of 1.99 and a Reynolds number of 6.0 million, based on the body length. The tests were performed through an angle-of-attack range of -5 deg to 28 deg to investigate the effects on the aerodynamic characteristics of roll angle, wing-tail interdigitation, wing deflection, and interference among the components (body, wing, and tail). Theoretical lift and moment characteristics of the configuration and its components were calculated by the use of existing theoretical methods which have been modified for application to high angles of attack, and these characteristics are compared with experiment. The lift and drag characteristics of all combinations of the body, wing, and tail were independent of roll angle throughout the angle-of-attack range. The pitching-moment characteristics of the body-wing and body-wing- tail combinations, however, were influenced significantly by the roll angle at large angles of attack (greater than 10 deg). A roll from 0 deg (one pair of wing panels horizontal) to 45 deg caused a forward shift in the center of pressure which was of the same magnitude for both of these combinations, indicating that this shift originated from body-wing interference effects. A favorable lift - interference effect (lift of the combination greater than the sum of the lifts of the components) and a rearward shift in the center of pressure from a position corresponding to that for the components occurred at small angles of attack when the body was combined with either the exposed wing or tail surfaces. These lift and center-of-pressure interference effects were gradually reduced to zero as the angle of attack was increased to large values. The effect of wing-tail interference, which influenced primarily the pitching-moment characteristics, is dependent on the

  2. Aerodynamic flow quality and acoustic characteristics of the 40- by 80-foot test section circuit of the National Full-Scale Aerodynamic Complex

    NASA Technical Reports Server (NTRS)

    Olson, Lawrence E.; Zell, Peter T.; Soderman, Paul T.; Falarski, Michael D.; Corsiglia, Victor R.; Edenborough, H. Kipling

    1988-01-01

    The 40- by 80-foot wind tunnel circuit of the National Full-Scale Aerodynamic Complex (NFAC) has recently undergone major modifications and subsequently completed final acceptance testing. The initial testing and calibration of the wind tunnel are described and in many cases these results are compared with predictions derived from model tests and theoretical analyses. The wind tunnel meets or exceeds essentially all performance objectives. The facility runs smoothly and routinely at its maximum test-section velocity of 300 knots (Mach number = 0.45). An effective cooling air exchange system enables the wind tunnel to operate indefinitely at this maximum power condition. Throughout the operating envelope of the wind tunnel the test-section dynamic pressure is uniform to within + or - 0.5 deg, and the axial component of turbulence is generally less than 0.5 percent. Acoustic measurements indicate that, due to the low noise fans and acoustic treatment in the wind-tunnel circuit and test section, the background noise level in the test section is comparable to other large-scale acoustic wind tunnels in the United States and abroad.

  3. Configuration Aerodynamics: Past - Present - Future

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Agrawal, Shreekant; Bencze, Daniel P.; Kulfan, Robert M.; Wilson, Douglas L.

    1999-01-01

    The Configuration Aerodynamics (CA) element of the High Speed Research (HSR) program is managed by a joint NASA and Industry team, referred to as the Technology Integration Development (ITD) team. This team is responsible for the development of a broad range of technologies for improved aerodynamic performance and stability and control characteristics at subsonic to supersonic flight conditions. These objectives are pursued through the aggressive use of advanced experimental test techniques and state of the art computational methods. As the HSR program matures and transitions into the next phase the objectives of the Configuration Aerodynamics ITD are being refined to address the drag reduction needs and stability and control requirements of High Speed Civil Transport (HSCT) aircraft. In addition, the experimental and computational tools are being refined and improved to meet these challenges. The presentation will review the work performed within the Configuration Aerodynamics element in 1994 and 1995 and then discuss the plans for the 1996-1998 time period. The final portion of the presentation will review several observations of the HSR program and the design activity within Configuration Aerodynamics.

  4. A Subsonic Wind-Tunnel Study to Determine the Buffet and Static Aerodynamic Characteristics of a Systematic Series of Wings. Phase 1

    NASA Technical Reports Server (NTRS)

    Ray, Edward J.; Taylor, Robert T.

    1968-01-01

    A wind-tunnel investigation has been conducted in the Langley High-Speed 7- by 10-Foot Tunnel to determine the buffet and static aerodynamic characteristics of a systematic wing series at Mach numbers ranging from 0.23 to 0.94. The results have indicated that for a given Mach number, the wings which display superior aerodynamic efficiency characteristics generally display the highest buffet free lift coefficient. The characteristics exhibited by the wings which were considered have indicated that correlations can be made between the onset of buffet and selected divergences in the static aerodynamic characteristics. Axial force has been found to be the most sensitive static component to the onset of buffeting.

  5. Numerical and experimental investigation on aerodynamic performance of small axial flow fan with hollow blade root

    NASA Astrophysics Data System (ADS)

    Li, Zhang; Jin, Yingzi; Huashu, Dou; Yuzhen, Jin

    2013-10-01

    To reduce the influence of adverse flow conditions at the fan hub and improve fan aerodynamic performance, a modification of conventional axial fan blades with numerical and experimental investigation is presented. Hollow blade root is manufactured near the hub. The numerical and experimental results show that hollow blade root has some effect on the static performance. Static pressure of the modified fan is generally the same with that of the datum fan, while, the efficiency curve of the modified fan has a different trend with that of the datum fan. The highest efficiency of the modified fan is 10% greater than that of the datum fan. The orthogonal experimental results of fan noise show that hollow blade root is a feasible method of reducing fan noise, and the maximum value of noise reduction is about 2 dB. The factors affecting the noise reduction of hollow blade root are in the order of importance as follows: hollow blade margin, hollow blade height and hollow blade width. The much smoother pressure distribution of the modified fan than that of the datum fan is the main mechanism of noise reduction of hollow blade root. The research results will provide the proof of the parameter optimization and the structure design for high performance and low noise small axial fans.

  6. Rather than resonance, flapping wing flyers may play on aerodynamics to improve performance.

    PubMed

    Ramananarivo, Sophie; Godoy-Diana, Ramiro; Thiria, Benjamin

    2011-04-12

    Saving energy and enhancing performance are secular preoccupations shared by both nature and human beings. In animal locomotion, flapping flyers or swimmers rely on the flexibility of their wings or body to passively increase their efficiency using an appropriate cycle of storing and releasing elastic energy. Despite the convergence of many observations pointing out this feature, the underlying mechanisms explaining how the elastic nature of the wings is related to propulsive efficiency remain unclear. Here we use an experiment with a self-propelled simplified insect model allowing to show how wing compliance governs the performance of flapping flyers. Reducing the description of the flapping wing to a forced oscillator model, we pinpoint different nonlinear effects that can account for the observed behavior--in particular a set of cubic nonlinearities coming from the clamped-free beam equation used to model the wing and a quadratic damping term representing the fluid drag associated to the fast flapping motion. In contrast to what has been repeatedly suggested in the literature, we show that flapping flyers optimize their performance not by especially looking for resonance to achieve larger flapping amplitudes with less effort, but by tuning the temporal evolution of the wing shape (i.e., the phase dynamics in the oscillator model) to optimize the aerodynamics.

  7. Aerodynamic performance of an airfoil with a prescribed wall protuberance at low Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Duque-Daza, Carlos; Mejia, Cristian; Camacho, Diego; Lockerby, Duncan

    2016-11-01

    Numerical simulations of flow around a modified NACA0012 airfoil, featuring a small surface perturbation on the upper wall, were performed at two low Reynolds numbers. The aerodynamic performance was examined under conditions of incompressible steady state flow. Simulations at different angles of attack (AOA) were performed: 0, 6, 9.25 and 12 degrees for Re =5000, and 6, 9.25 and 12 for Re =50000. The effect of the wall-perturbation was assessed in terms of changes of drag and lift coefficients, and alterations of the upper wall turbulent boundary layer. Examination of mean velocity profiles reveals that the wall perturbation promotes boundary-layer separation near the leading edge and increase of the skin friction drag. An arguably improvement of the effectiveness, i.e. ratio of lift to drag, was observed for the modified profile for Re = 5000, especially at AOA of 6 degrees. This effect seems to be caused by a double effect: boundary layer separation approaching the leading edge and an increase of the lift coefficient caused by the larger pressure drop on the upper surface. The effect of the perturbation was always negative for the airfoil operating at Re =50000, independently of AOA.

  8. Space shuttle: Aerodynamic stability, control effectiveness and drag characteristics of a shuttle orbiter configuration at Mach numbers from 0.6 to 4.96

    NASA Technical Reports Server (NTRS)

    Ramsey, P. E.

    1972-01-01

    Experimental aerodynamic investigations were conducted in the NASA/MSFC 14-inch Trisonic Wind Tunnel from Sept. 27 to Oct. 7, 1972 on a 0.004 scale model of the NR ATP baseline shuttle orbiter configuration. Six component aerodynamic force and moment data were recorded at 0 deg sideslip angle over an angle of attack range from 0 to 20 deg for Mach numbers of 0.6 to 4.96, 20 to 40 deg for Mach numbers of 0.6, 0.9, 2.99, and 4.96, and 40 to 60 deg for Mach numbers of 2.99 and 4.96. Data were obtained over a sideslip range of -10 to 10 deg at 0, 10, and 20 deg angles of attack over the Mach range and 30 and 50 deg at Mach numbers of 2.99 and 4.96. The purpose of the test was to define the buildup, performance, stability, and control characteristics of the orbiter configuration. The model parameters, were: body alone; body-wing; body-wing-tail; elevon deflections of 0, 10, -20, and -40 deg both full and split); aileron deflections of plus or minus 10 deg (full and split); rudder flares of 10 and 40 deg, and a rudder deflection of 15 deg about the 10 and 40 deg flare positions.

  9. Aerodynamic Characteristics of a Four-Propeller Tilt-Wing VTOL Model with Twin Vertical Tails, Including Effects of Ground Proximity

    NASA Technical Reports Server (NTRS)

    Grunwald, Kalman J.

    1961-01-01

    Results are presented of a wind-tunnel investigation of the aerodynamic stability, control, and performance characteristics of a model of a four-propeller tilt-wing VTOL airplane employing flaps and speed brakes through the transition speed range. The results indicate that the wing was stalled for steady level flight for all conditions of the investigation; however, the flapped configuration did produce a higher maximum lift. The effectiveness of the flap in delaying the stall in the present investigation was not as great as in some previous investigations because the flap used was smaller than that used previously. The wing stall resulted in an appreciable reduction of aileron effectiveness during the transition. Out of ground effect the low horizontal tail did not appear to be in an adverse flow field as had been expected and showed no erratic changes in effectiveness; however, in ground effect a large nose-down moment was experienced by the model. In general, the lateral aerodynamic data indicate that the configuration is directionally stable and possesses positive dihedral effect throughout the transition, and the data show no signs of erratic flow at the vertical tails.

  10. An Aerodynamic Performance Evaluation of the NASA/Ames Research Center Advanced Concepts Flight Simulator. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Donohue, Paul F.

    1987-01-01

    The results of an aerodynamic performance evaluation of the National Aeronautics and Space Administration (NASA)/Ames Research Center Advanced Concepts Flight Simulator (ACFS), conducted in association with the Navy-NASA Joint Institute of Aeronautics, are presented. The ACFS is a full-mission flight simulator which provides an excellent platform for the critical evaluation of emerging flight systems and aircrew performance. The propulsion and flight dynamics models were evaluated using classical flight test techniques. The aerodynamic performance model of the ACFS was found to realistically represent that of current day, medium range transport aircraft. Recommendations are provided to enhance the capabilities of the ACFS to a level forecast for 1995 transport aircraft. The graphical and tabular results of this study will establish a performance section of the ACFS Operation's Manual.

  11. The aerodynamic design and performance of the General Electric/NASA EEE fan. [Energy Efficient Engine

    NASA Technical Reports Server (NTRS)

    Sullivan, T. J.; Hager, R. D.

    1983-01-01

    The aerodynamic design and test results of the fan and quarter-stage component for the GE/NASA Energy Efficient Engine (EEE) are presented. The fan is a high bypass ratio, single-stage design having 32 part-span shrouded rotor blades, coupled with a unique quarter-stage arrangement that provides additional core-stream pressure ratio and particle separation. The fan produces a bypass pressure ratio of 1.65 at the exit of the low aspect ratio vane/frame and a core-stream pressure ratio of 1.67 at the entrance to the core frame struts. The full-scale fan vehicle was instrumented, assembled and tested as a component in November 1981. Performance mapping was conducted over a range of speeds and bypass ratios using individually-controlled bypass and core-stream discharge valves. The fan bypass and core-stream test data showed excellent results, with the fan exceeding all performance goals at the important engine operating conditions.

  12. Low-speed wind-tunnel investigation of the aerodynamic and acoustic performance of a translating grid choked flow inlet

    NASA Technical Reports Server (NTRS)

    Abbott, J. M.; Miller, B. A.; Golladay, R. L.

    1974-01-01

    The aerodynamic and acoustic performance of a translating grid choked-flow inlet was determined in a low-speed wind tunnel at free-stream velocities of 24, 32, and 45 m/sec and incidence angles of 0, 10, 20, 30, 35, 40, 45, and 50 deg. The inlet was sized to fit a 13.97- centimeter-diameter fan with a design weight flow of 2.49 kg/sec. Measurements were made to determine inlet total pressure recovery, flow distortion, and sound pressure level for both choked and unchoked geometries over a range of inlet weight flows. For the unchoked geometry, inlet total pressure recovery ranged from 0.983 to 0.989 at incidence angles less than 40 deg. At 40 deg incidence angle, inlet cowl separation was encountered which resulted in lower values of pressure recovery and higher levels of fan broadband noise. For the choked geometry, increasing total pressure losses occurred with increasing inlet weight flow that prevented the inlet from reaching full choked conditions with the particular fan used. These losses were attributed to the high Mach number drag rise characteristics of airfoil grid. At maximum attainable inlet weight flow, the total pressure recovery at static conditions was 0.935. The fan blade passing frequency and other fan generated pure tones were eliminated from the noise spectrum, but the broadband level was increased.

  13. Measured unsteady transonic aerodynamic characteristics of an elastic supercritical wing with an oscillating control surface

    NASA Technical Reports Server (NTRS)

    Seidel, D. A.; Sandford, M. C.; Eckstrom, C. V.

    1985-01-01

    Transonic steady and unsteady aerodynamic data were measured on a large elastic wing in the NASA Langley Transonic Dynamics Tunnel. The wing had a supercritical airfoil shape and a leading-edge sweepback of 28.8 deg. The wing was heavily instrumented to measure both static and dynamic pressures and deflections. A hydraulically driven outboard control surface was oscillated to generate unsteady airloads on the wing. Representative results from the wind tunnel tests are presented and discussed, and the unexpected occurrence of an unusual dynamic wing instability, which was sensitive to angle of attack, is reported.

  14. Aerodynamic characteristics of airfoils VI : continuation of reports nos. 93, 124, 182, 244, and 286

    NASA Technical Reports Server (NTRS)

    1930-01-01

    This collection of data on airfoils has been made from the published reports of a number of the leading aerodynamic laboratories of this country and Europe. The information which was originally expressed according to the different customs of the several laboratories is here presented in a uniform series of charts and tables suitable for use of designing engineers and for purposes of general reference. The authority for the results here presented is given as the name of the laboratory at which the experiments were conducted, with the size of the model, wind velocity, and year of test.

  15. Analysis of preflutter and postflutter characteristics with motion-matched aerodynamic forces

    NASA Technical Reports Server (NTRS)

    Cunningham, H. J.

    1978-01-01

    The development of the equations of dynamic equilibrium for a lifting surface from Lagrange's equation is reviewed and restated for general exponential growing and decaying oscillatory motion. Aerodynamic forces for this motion are obtained from the three-dimensional supersonic kernel function that is newly generalized to complex reduced frequencies. Illustrative calculations were made for two flutter models at supersonic Mach numbers. Preflutter and postflutter motion isodecrement curves were obtained. This type of analysis can be used to predict preflutter behavior during flutter testing and to predict postflutter behavior for use in the design of flutter suppression systems.

  16. Calculation of the aerodynamic characteristics of tapered wings with partial-span flaps

    NASA Technical Reports Server (NTRS)

    Person, Henry A; Anderson, Raymond F

    1939-01-01

    Factors derived from wing theory are presented. By means of these factors, the angle of zero lift, the lift-curve slope, the pitching moment, the aerodynamic-center position, and the induced drag of tapered wings with partial-span flaps may be calculated. The factors are given for wings of aspect ratios 6 and 10 , of taper ratios from 0.25 to 1.00, and with flaps of various length. An example is presented of the method of application of the factors. Fair agreement with experimental results is shown for two wings of different taper ratio having plain flaps of various spacing.

  17. Error Estimate of the Ares I Vehicle Longitudinal Aerodynamic Characteristics Based on Turbulent Navier-Stokes Analysis

    NASA Technical Reports Server (NTRS)

    Abdol-Hamid, Khaled S.; Ghaffari, Farhad

    2011-01-01

    Numerical predictions of the longitudinal aerodynamic characteristics for the Ares I class of vehicles, along with the associated error estimate derived from an iterative convergence grid refinement, are presented. Computational results are based on the unstructured grid, Reynolds-averaged Navier-Stokes flow solver USM3D, with an assumption that the flow is fully turbulent over the entire vehicle. This effort was designed to complement the prior computational activities conducted over the past five years in support of the Ares I Project with the emphasis on the vehicle s last design cycle designated as the A106 configuration. Due to a lack of flight data for this particular design s outer mold line, the initial vehicle s aerodynamic predictions and the associated error estimates were first assessed and validated against the available experimental data at representative wind tunnel flow conditions pertinent to the ascent phase of the trajectory without including any propulsion effects. Subsequently, the established procedures were then applied to obtain the longitudinal aerodynamic predictions at the selected flight flow conditions. Sample computed results and the correlations with the experimental measurements are presented. In addition, the present analysis includes the relevant data to highlight the balance between the prediction accuracy against the grid size and, thus, the corresponding computer resource requirements for the computations at both wind tunnel and flight flow conditions. NOTE: Some details have been removed from selected plots and figures in compliance with the sensitive but unclassified (SBU) restrictions. However, the content still conveys the merits of the technical approach and the relevant results.

  18. Longitudinal aerodynamic characteristics of a generic fighter model with a wing designed for sustained transonic maneuver conditions

    NASA Technical Reports Server (NTRS)

    Ferris, J. C.

    1986-01-01

    A wind-tunnel investigation was made to determine the longitudinal aerodynamic characteristics of a fixed-wing generic fighter model with a wing designed for sustained transonic maneuver conditions. The airfoil sections on the wing were designed with a two-dimensional nonlinear computer code, and the root and tip section were modified with a three-dimensional code. The wing geometric characteristics were as follows: a leading-edge sweep of 45 degrees, a taper ratio of 0.2141, an aspect ratio of 3.30, and a thickness ratio of 0.044. The model was investigated at Mach numbers from 0.600 to 1.200, at Reynolds numbers, based on the model reference length, from 2,560,000 to 3,970,000, and through a model angle-of-attack range from -5 to +18 degrees.

  19. Predicting aerodynamic characteristics of vortical flows on three-dimensional configurations using a surface-singularity panel method

    NASA Technical Reports Server (NTRS)

    Maskew, B.

    1983-01-01

    A general low-order surface-singularity panel method is used to predict the aerodynamic characteristics of a problem where a wing-tip vortex from one wing closely interacts with an aft mounted wing in a low Reynolds Number flow; i.e., 125,000. Nonlinear effects due to wake roll-up and the influence of the wings on the vortex path are included in the calculation by using a coupled iterative wake relaxation scheme. The interaction also affects the wing pressures and boundary layer characteristics: these effects are also considered using coupled integral boundary layer codes and preliminary calculations using free vortex sheet separation modelling are included. Calculated results are compared with water tunnel experimental data with generally remarkably good agreement.

  20. Experimental study of the effects of Reynolds number on high angle of attack aerodynamic characteristics of forebodies during rotary motion

    NASA Technical Reports Server (NTRS)

    Pauley, H.; Ralston, J.; Dickes, E.

    1995-01-01

    The National Aeronautics and Space Administration and the Defense Research Agency (United Kingdom) have ongoing experimental research programs in rotary-flow aerodynamics. A cooperative effort between the two agencies is currently underway to collect an extensive database for the development of high angle of attack computational methods to predict the effects of Reynolds number on the forebody flowfield at dynamic conditions, as well as to study the use of low Reynolds number data for the evaluation of high Reynolds number characteristics. Rotary balance experiments, including force and moment and surface pressure measurements, were conducted on circular and rectangular aftbodies with hemispherical and ogive noses at the Bedford and Farnborough wind tunnel facilities in the United Kingdom. The bodies were tested at 60 and 90 deg angle of attack for a wide range of Reynolds numbers in order to observe the effects of laminar, transitional, and turbulent flow separation on the forebody characteristics when rolling about the velocity vector.

  1. Low-speed aerodynamic characteristics of a 17-percent-thick medium speed airfoil designed for general aviation applications

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Beaseley, W. D.

    1980-01-01

    Wind tunnel tests were conducted to determine the low speed two dimensional aerodynamic characteristics of a 17 percent thick medium speed airfoil (MS(1)-0317) designed for general aviation applications. The results were compared with data for the 17 percent thick low speed airfoil (LS(1)-0417) and the 13 percent thick medium speed airfoil (MS(1)-0313). Theoretical predictions of the drag rise characteristics of this airfoil are also provided. The tests were conducted in the Langley low turbulence pressure tunnel over a Mach number range from 0.10 to 0.32, a chord Reynolds number range from 2 million to 12 million, and an angle of attack range from about -8 to 20 deg.

  2. 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

  3. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    NASA Technical Reports Server (NTRS)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2015-01-01

    The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90deg-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105 percent of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100 percent design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

  4. Improvement of the aerodynamic performance by wing flexibility and elytra–hind wing interaction of a beetle during forward flight

    PubMed Central

    Le, Tuyen Quang; Truong, Tien Van; Park, Soo Hyung; Quang Truong, Tri; Ko, Jin Hwan; Park, Hoon Cheol; Byun, Doyoung

    2013-01-01

    In this work, the aerodynamic performance of beetle wing in free-forward flight was explored by a three-dimensional computational fluid dynamics (CFDs) simulation with measured wing kinematics. It is shown from the CFD results that twist and camber variation, which represent the wing flexibility, are most important when determining the aerodynamic performance. Twisting wing significantly increased the mean lift and camber variation enhanced the mean thrust while the required power was lower than the case when neither was considered. Thus, in a comparison of the power economy among rigid, twisting and flexible models, the flexible model showed the best performance. When the positive effect of wing interaction was added to that of wing flexibility, we found that the elytron created enough lift to support its weight, and the total lift (48.4 mN) generated from the simulation exceeded the gravity force of the beetle (47.5 mN) during forward flight. PMID:23740486

  5. Correlation Between Geometric Similarity of Ice Shapes and the Resulting Aerodynamic Performance Degradation: A Preliminary Investigation Using WIND

    NASA Technical Reports Server (NTRS)

    Wright, William B.; Chung, James

    1999-01-01

    Aerodynamic performance calculations were performed using WIND on ten experimental ice shapes and the corresponding ten ice shapes predicted by LEWICE 2.0. The resulting data for lift coefficient and drag coefficient are presented. The difference in aerodynamic results between the experimental ice shapes and the LEWICE ice shapes were compared to the quantitative difference in ice shape geometry presented in an earlier report. Correlations were generated to determine the geometric features which have the most effect on performance degradation. Results show that maximum lift and stall angle can be correlated to the upper horn angle and the leading edge minimum thickness. Drag coefficient can be correlated to the upper horn angle and the frequency-weighted average of the Fourier coefficients. Pitching moment correlated with the upper horn angle and to a much lesser extent to the upper and lower horn thicknesses.

  6. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    NASA Technical Reports Server (NTRS)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2014-01-01

    The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90º-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105% of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100% design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

  7. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    NASA Technical Reports Server (NTRS)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2014-01-01

    The measured aerodynamic performance of a compact, high work factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90-bend, and exit guide vane (EGV), is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level are reported for operation between 70 to 105 of design corrected speed, with subcomponent (impeller, diffuser, and exitguide-vane) detailed flow field measurements presented and discussed at the 100 design-speed condition. Individual component losses from measurements are compared with pre-test predictions on a limited basis.

  8. QCSEE under-the-wing engine-wing-flap aerodynamic profile characteristics

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1982-01-01

    As part of a broad-based NASA program to provide a technology base for future propulsion requirements for powered-lift aircraft, the Quiet, Clean, Short-Haul, Experimental Engine (QCSEE) program was begun by the Lewis Research Center in 1974. The initial buildup of the under-the-wing (UTW) engine was tested by the contractor at his test site. The UTW engine was delivered to Lewis in 1978 for further testing with wing and flap segments simulating an installation on a short-haul transport aircraft. The engine was also tested alone as an aid in identifying the various noise sources and their levels. As part of these tests the aerodynamic profiles at the exhaust nozzle and on the surfaces and in the wake of the wing-flap system were measured. This report documents, in plots and tabular form, the significant results from those tests. The results are presented as tabulations of aerodynamic data for all of the test points and as profiles of pressure, temperature, velocity, and normalized velocity and pressure for selected conditions. One of the main conclusions was that the measured flap surface temperatures were surprisingly low for both approach and takeoff flap settings.

  9. Aerodynamics of cyclist posture, bicycle and helmet characteristics in time trial stage.

    PubMed

    Chabroux, Vincent; Barelle, Caroline; Favier, Daniel

    2012-07-01

    The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist's upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results indicate that variations in the TT cyclist posture, the saddle position and the helmet visor can produce a significant gain in time (up to 2.2%) during stages.

  10. Experimental Hypersonic Aerodynamic Characteristics of the Space Shuttle Orbiter for a Range of Damage Scenarios

    NASA Technical Reports Server (NTRS)

    Brauckmann, Gregory J.; Scallion, William I.

    2004-01-01

    Aerodynamic tests in support of the Columbia accident investigation were conducted in two hypersonic wind tunnels at the NASA Langley Research Center, the 20-Inch Mach 6 Air Tunnel and the 20-Inch CF4 Tunnel. The primary purpose of these tests was to measure the forces and moments generated by a variety of outer mold line alterations (damage scenarios) using 0.0075-scale models of the Space Shuttle Orbiter. Simultaneously acquired global heat transfer mappings were obtained for a majority of the configurations tested. Test parametrics included angles of attack from 38 to 42 deg, unit Reynolds numbers from 0.3 x 10(exp 6) to 3.0 x 10(exp 6) per foot, and normal shock density ratios of 5 (Mach 6 air) and 12 (CF4). The damage scenarios evaluated included asymmetric boundary layer transition, gouges in the windward surface thermal protection system tiles, wing leading edge damage (partially and fully missing reinforced carbon-carbon (RCC) panels), deformation of the wing windward surface, and main landing gear and/or door deployment. The measured aerodynamic increments for the damage scenarios examined were generally small in magnitude, as were the flight-derived values during most of the entry prior to loss of communication. A progressive damage scenario is presented that qualitatively matches the flight observations for the STS-107 entry.

  11. Effects of independent variation of Mach and Reynolds numbers on the low-speed aerodynamic characteristics of the NACA 0012 airfoil section

    NASA Technical Reports Server (NTRS)

    Ladson, Charles L.

    1988-01-01

    A comprehensive data base is given for the low speed aerodynamic characteristics of the NACA 0012 airfoil section. The Langley low-turbulence pressure tunnel is the facility used to obtain the data. Included in the report are the effects of Mach number and Reynolds number and transition fixing on the aerodynamic characteristics. Presented are also comparisons of some of the results with previously published data and with theoretical estimates. The Mach number varied from 0.05 to 0.36. The Reynolds number, based on model chord, varied from 3 x 10 to the 6th to 12 x 10 to the 6th power.

  12. On the influence of airfoil deviations on the aerodynamic performance of wind turbine rotors

    NASA Astrophysics Data System (ADS)

    Winstroth, J.; Seume, J. R.

    2016-09-01

    The manufacture of large wind turbine rotor blades is a difficult task that still involves a certain degree of manual labor. Due to the complexity, airfoil deviations between the design airfoils and the manufactured blade are certain to arise. Presently, the understanding of the impact of manufacturing uncertainties on the aerodynamic performance is still incomplete. The present work analyzes the influence of a series of airfoil deviations likely to occur during manufacturing by means of Computational Fluid Dynamics and the aeroelastic code FAST. The average power production of the NREL 5MW wind turbine is used to evaluate the different airfoil deviations. Analyzed deviations include: Mold tilt towards the leading and trailing edge, thick bond lines, thick bond lines with cantilever correction, backward facing steps and airfoil waviness. The most severe influences are observed for mold tilt towards the leading and thick bond lines. By applying the cantilever correction, the influence of thick bond lines is almost compensated. Airfoil waviness is very dependent on amplitude height and the location along the surface of the airfoil. Increased influence is observed for backward facing steps, once they are high enough to trigger boundary layer transition close to the leading edge.

  13. Effect of longitudinal ridges on the aerodynamic performance of a leatherback turtle model

    NASA Astrophysics Data System (ADS)

    Bang, Kyeongtae; Kim, Jooha; Kim, Heesu; Lee, Sang-Im; Choi, Haecheon

    2012-11-01

    Leatherback sea turtles (Dermochelys coriacea) are known as the fastest swimmer and the deepest diver in the open ocean among marine turtles. Unlike other marine turtles, leatherback sea turtles have five longitudinal ridges on their carapace. To investigate the effect of these longitudinal ridges on the aerodynamic performance of a leatherback turtle model, the experiment is conducted in a wind tunnel at Re = 1.0 × 105 - 1.4 × 106 (including that of real leatherback turtle in cruising condition) based on the model length. We measure the drag and lift forces on the leatherback turtle model with and without longitudinal ridges. The presence of longitudinal ridges increases both the lift and drag forces on the model, but increases the lift-to-drag ratio by 15 - 40%. We also measure the velocity field around the model with and without the ridges using particle image velocimetry. More details will be shown in the presentation. Supported by the NRF program (2011-0028032).

  14. Aerodynamic performance of a wing with a deflected tip-mounted reverse half-delta wing

    NASA Astrophysics Data System (ADS)

    Lee, T.; Su, Y. Y.

    2012-11-01

    The impact of a tip-mounted 65°-sweep reverse half-delta wing (RHDW), set at different deflections, on the aerodynamic performance of a rectangular NACA 0012 wing was investigated experimentally at Re = 2.45 × 105. This study is a continuation of the work of Lee and Su (Exp Fluids 52(6):1593-1609, 2012) on the passive control of wing tip vortex by the use of a reverse half-delta wing. The present results show that for RHDW deflection with -5° ≤ δ ≤ +15°, the lift was found to increase nonlinearly with increasing δ compared to the baseline wing. The lift increment was accompanied by an increased total drag. For negative RHDW deflection with δ < -5°, the RHDW-induced lift decrement was, however, accompanied by an improved drag. The deflected RHDW also significantly modified and weakened the tip vortex, leading to a persistently lowered lift-induced drag, regardless of its deflection, compared to the baseline wing. Physical mechanisms responsible for the observed RHDW-induced phenomenon were also discussed.

  15. Aerodynamic Performance of an Active Flow Control Configuration Using Unstructured-Grid RANS

    NASA Technical Reports Server (NTRS)

    Joslin, Ronald D.; Viken, Sally A.

    2001-01-01

    This research is focused on assessing the value of the Reynolds-Averaged Navier-Stokes (RANS) methodology for active flow control applications. An experimental flow control database exists for a TAU0015 airfoil, which is a modification of a NACA0015 airfoil. The airfoil has discontinuities at the leading edge due to the implementation of a fluidic actuator and aft of mid chord on the upper surface. This paper documents two- and three-dimensional computational results for the baseline wing configuration (no control) with tile experimental results. The two-dimensional results suggest that the mid-chord discontinuity does not effect the aerodynamics of the wing and can be ignored for more efficient computations. The leading-edge discontinuity significantly affects tile lift and drag; hence, the integrity of the leading-edge notch discontinuity must be maintained in the computations to achieve a good match with the experimental data. The three-dimensional integrated performance results are in good agreement with the experiments inspite of some convergence and grid resolution issues.

  16. Aerodynamic and Acoustic Performance of Two Choked-Flow Inlets Under Static Conditions

    NASA Technical Reports Server (NTRS)

    Miller, B. A.; Abbott, J. M.

    1972-01-01

    Tests were conducted to determine the aerodynamic and acoustic performance of two choking flow inlets under static conditions. One inlet choked the flow in the cowl throat by an axial translation of the inlet centerbody. The other inlet employed a translating grid of airfoils to choke the flow. Both inlets were sized to fit a 13.97 cm diameter fan with a design weight flow of 2.49 kg/sec. The inlets were operated in both the choked and unchoked modes over a range of weight flows. Measurements were made of inlet pressure recovery, flow distortion, surface static pressure distribution, and fan noise suppression. Choking of the translating centerbody inlet reduced blade passing frequency noise by 29 db while yielding a total pressure recovery of 0.985. Noise reductions were also measured at 1/3-octave band center frequencies of 2500, 5000, and 20,000 cycles. The translating grid inlet gave a total pressure recovery of 0.968 when operating close to the choking weight flow. However, an intermittent high intensity noise source was encountered with this inlet that precluded an accurate measurement of inlet noise suppression.

  17. Effect of milling machine roughness and wing dihedral on the supersonic aerodynamic characteristics of a highly swept wing

    NASA Technical Reports Server (NTRS)

    Darden, Christine M.

    1989-01-01

    An experimental investigation was conducted to assess the effect of surface finish on the longitudinal and lateral aerodynamic characteristics of a highly-swept wing at supersonic speeds. A study of the effects of wing dihedral was also made. Included in the tests were four wing models: three models having 22.5 degrees of outboard dihedral, identical except for surface finish, and a zero-dihedral, smooth model of the same planform for reference. Of the three dihedral models, two were taken directly from the milling machine without smoothing: one having a maximum scallop height of 0.002 inches and the other a maximum scallop height of 0.005 inches. The third dihedral model was handfinished to a smooth surface. Tests were conducted in Test Section 1 of the Unitary Plan Wind Tunnel at NASA-Langley over a range of Mach numbers from 1.8 to 2.8, a range of angle of attack from -5 to 8 degrees, and at a Reynolds numbers per foot of 2 x 10(6). Selected data were also taken at a Reynolds number per foot of 6 x 10(6). Drag coefficient increases, with corresponding lift-drag ratio decreases were the primary aerodynamic effects attributed to increased surface roughness due to milling machine grooves. These drag and lift-drag ratio increments due to roughness increased as Reynolds number increased.

  18. Aerodynamic Characteristics of a Feathered Dinosaur Measured Using Physical Models. Effects of Form on Static Stability and Control Effectiveness

    PubMed Central

    Evangelista, Dennis; Cardona, Griselda; Guenther-Gleason, Eric; Huynh, Tony; Kwong, Austin; Marks, Dylan; Ray, Neil; Tisbe, Adrian; Tse, Kyle; Koehl, Mimi

    2014-01-01

    We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While M. gui lived after Archaeopteryx and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver. PMID:24454820

  19. Effects of forebody strakes and Mach number on overall aerodynamic characteristics of configuration with 55 deg cropped delta wing

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Rogers, Lawrence W.

    1992-01-01

    A wind tunnel data base was established for the effects of chine-like forebody strakes and Mach number on the longitudinal and lateral-directional characteristics of a generalized 55 degree cropped delta wing-fuselage-centerline vertical tail configuration. The testing was conducted in the 7- by 10-Foot Transonic Tunnel at the David Taylor Research Center at free-stream Mach numbers of 0.40 to 1.10 and Reynolds numbers based on the wing mean aerodynamic chord of 1.60 x 10(exp 6) to 2.59 x 10(exp 6). The best matrix included angles of attack from 0 degree to a maximum of 28 degree, angles of sidesip of 0, +5, and -5 degrees, and wing leading-edge flat deflection angles of 0 and 30 degrees. Key flow phenomena at subsonic and transonic conditions were identified by measuring off-body flow visualization with a laser screen technique. These phenomena included coexisting and interacting vortex flows and shock waves, vortex breakdown, vortex flow interactions with the vertical tail, and vortices induced by flow separation from the hinge line of the deflected wing flap. The flow mechanisms were correlated with the longitudinal and lateral-directional aerodynamic data trends.

  20. Aerodynamic performances of three fan stator designs operating with rotor having tip speed of 337 meters per second and pressure ratio of 1.54. 1: Experimental performance

    NASA Technical Reports Server (NTRS)

    Gelder, T. F.

    1980-01-01

    The aerodynamic performances of four stator-blade rows are presented and evaluated. The aerodynamic designs of two of these stators were compromised to reduce noise, a third design was not. On a calculated operating line passing through the design point pressure ratio, the best stator had overall pressure-ratio and efficiency decrements of 0.031 and 0.044, respectively, providing a stage pressure ratio of 1.483 and efficiency of 0.865. The other stators showed some correctable deficiencies due partly to the design compromises for noise. In the end-wall regions blade-element losses were significantly less for the shortest chord studied.

  1. The aerodynamic and acoustic characteristics of an over-the-wing target-type thrust reverser model

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.

    1976-01-01

    A static test of a large-scale, over-the-wing (OTW) powered-lift model was performed. The OTW propulsion system had been modified to incorporate a simple target-type thrust reverser as well as the normal rectangular OTW exhaust nozzle. Tests were performed in both the reverse thrust and approach configurations. The thrust reverser noise created by jet turbulence mixing and the OTW approach noise were both low frequency and broadband. When scaled to a 45,400-kg (100,000-lb) aircraft, the thrust reverser and approach configurations produced peak 152-m (500-ft) sideline perceived noise levels of 110 and 105 PNdB, respectively. The aerodynamic performance of the model showed that 50% or greater reverser effectiveness can be achieved without experiencing ingestion of exhaust gas or ground debris into the engine inlets.

  2. Analysis of the effect of engine characteristics on the external aerodynamics of STOL wing propulsion systems

    NASA Technical Reports Server (NTRS)

    Albers, J. A.

    1972-01-01

    The effects of engine presssure ratio, engine size, and engine location on the pressure distribution, lift coefficient, and flow field of a STOL wing propulsion system are presented. The flow variables of the engines are included in the two-dimensional potential flow analysis by considering the effects of mass flow coefficient at the engine inlet and thrust coefficient at the engine exit. A functional relation between these coefficients and engine pressure ratio is given. The results of this study indicate that the effect of engine pressure ratio on the external aerodynamics is a function of engine location. For engines located on the bottom of the wing, the highest pressure ratio engine resulted in the highest lift coefficient. For engines located on the top of the wing, the lowest pressure ratio engine resulted in the highest lift coefficient.

  3. Impact of pulsed blowing jet on aerodynamic characteristics of wind turbine airfoils

    NASA Astrophysics Data System (ADS)

    Bobonea, Andreea

    2012-11-01

    Wind turbine growth in size and weight made it impossible to control turbines passively as they were controlled in the past. Current efforts focus on increasing their aerodynamic efficiency and operational range through active flow control methods. One of the main methods of active flow control is the usage of blowing devices with constant or pulsed jets. By adding stored high-momentum air through slots into the boundary layer, they overcome adverse pressure gradients and postpone separation. Pulsed blowing sends short pulses rather than a continuous jet of fluid into the boundary layer and has been found to be more effective. Through CFD simulations over a 2D wind turbine airfoil, this research highlights the impact of different slot geometries with constant/pulsed blowing, on the effectiveness of this active flow control technique.

  4. Space shuttle: Aerodynamic characteristics of a 162-inch diameter solid rocket booster with and without strakes

    NASA Technical Reports Server (NTRS)

    Johnson, J. D.; Radford, W. D.; Rampy, J. M.

    1973-01-01

    Tests conducted at NASA-Langley have shown that a small flap or strake can generate a significant amount of lift on a circular cylinder with large cross flow. If strakes are placed on the opposite sides and ends on a circular body, a moment will be produced about the center of mass of the body. The purpose of this test was to determine the static-aerodynamic forces and moments of a 162-inch diameter SRB (PRR) with and without strakes. The total angle-of-attack range of the SRB test was from -10 to 190 degrees. Model roll angles were 0, 45, 90, and 135 degrees with some intermediate angles. The Mach range was from 0.6 to 3.48. The 0.00494 scale model was designated as MSFC No. 449.

  5. A Fundamental Study for Aerodynamic Characteristics of Supersonic Biplane Wing and Wing-Body Configurations

    NASA Astrophysics Data System (ADS)

    Odaka, Yusuke; Kusunose, Kazuhiro

    In order to develop a quiet supersonic transport, it is necessary to reduce shock waves around the transport. Shock waves, in general, are the cause of the airplane's sonic boom. Authors have been studying an aerodynamic feasibility of supersonic biplanes based on the concept of the Busemann biplane. In this paper, the three dimensional effect of wing geometries on their wave drags, including wing tip effects and the interference effects between the wing and a body (Wing-Body configurations) are investigated, using CFD code in Euler (inviscid) mode. As a result, we can conclude that the supersonic biplane wings at their design Mach number (M∞=1.7) are still capable of reducing wave drag significantly similar to that of the 2-D supersonic biplane.

  6. DSMC method on aerodynamic heating and temperature characteristic of hypersonic rarefied flows

    NASA Astrophysics Data System (ADS)

    Ma, Jing; Bao, Xingdong; Mao, Hongxia; Dong, Yanbing

    2016-10-01

    Aerodynamic heating is one of important factors affecting hypersonic aircraft design. The Direct Simulation Monte Carlo method (DSMC) has evolved years into a powerful numerical technique for the computation of complex, non-equilibrium gas flows. In atmospheric target, non-equilibrium conditions occur at high altitude and in regions of flow fields with small length scales. In this paper, the theoretical basis of the DSMC technique is discussed. In addition, the methods used in DSMC are described for simulation of high temperature, real gas effects and gas-surface interactions. Combined with the solution of heat transfer in material, heat-flux distribution and temperature distribution of the different shape structures was calculated in rarefied conditions.

  7. Aerodynamic Characterization of a Modern Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Hall, Robert M.; Holland, Scott D.; Blevins, John A.

    2011-01-01

    A modern launch vehicle is by necessity an extremely integrated design. The accurate characterization of its aerodynamic characteristics is essential to determine design loads, to design flight control laws, and to establish performance. The NASA Ares Aerodynamics Panel has been responsible for technical planning, execution, and vetting of the aerodynamic characterization of the Ares I vehicle. An aerodynamics team supporting the Panel consists of wind tunnel engineers, computational engineers, database engineers, and other analysts that address topics such as uncertainty quantification. The team resides at three NASA centers: Langley Research Center, Marshall Space Flight Center, and Ames Research Center. The Panel has developed strategies to synergistically combine both the wind tunnel efforts and the computational efforts with the goal of validating the computations. Selected examples highlight key flow physics and, where possible, the fidelity of the comparisons between wind tunnel results and the computations. Lessons learned summarize what has been gleaned during the project and can be useful for other vehicle development projects.

  8. The equivalent angle-of-attack method for estimating the nonlinear aerodynamic characteristics of missile wings and control surfaces

    NASA Technical Reports Server (NTRS)

    Hemsch, M. J.; Nielsen, J. N.

    1982-01-01

    A method has been developed for estimating the nonlinear aerodynamic characteristics of missile wing and control surfaces. The method is based on the following assumption: if a fin on a body has the same normal-force coefficient as a wing alone composed of two of the same fins joined together at their root chords, then the other force and moment coefficients of the fin and the wing alone are the same including the nonlinearities. The method can be used for deflected fins at arbitrary bank angles and at high angles of attack. In the paper, a full derivation of the method is given, its accuracy demonstrated and its use in extending missile data bases is shown.

  9. Effect of aileron deflections on the aerodynamic characteristics of a semispan model of a subsonic energy-efficient transport

    NASA Technical Reports Server (NTRS)

    Jacobs, P. F.

    1985-01-01

    An investigation was conducted in the Langley 8 Foot Transonic Pressure Tunnel to determine the effect of aileron deflections on the aerodynamic characteristics of a subsonic energy efficient transport (EET) model. The semispan model had an aspect ratio 10 supercritical wing and was configured with a conventionally located set of ailerons (i.e., a high speed aileron located inboard and a low speed aileron located outboard). Data for the model were taken over a Mach number range from 0.30 to 0.90 and an angle of attack range from approximately -2 deg to 10 deg. The Reynolds number was 2.5 million per foot for Mach number = 0.30 and 4 million per foot for the other Mach numbers. Model force and moment data, aileron effectiveness parameters, aileron hinge moment data, otherwise pressure distributions, and spanwise load data are presented.

  10. PROGRAM VSAERO: A computer program for calculating the non-linear aerodynamic characteristics of arbitrary configurations: User's manual

    NASA Technical Reports Server (NTRS)

    Maskew, B.

    1982-01-01

    VSAERO is a computer program used to predict the nonlinear aerodynamic characteristics of arbitrary three-dimensional configurations in subsonic flow. Nonlinear effects of vortex separation and vortex surface interaction are treated in an iterative wake-shape calculation procedure, while the effects of viscosity are treated in an iterative loop coupling potential-flow and integral boundary-layer calculations. The program employs a surface singularity panel method using quadrilateral panels on which doublet and source singularities are distributed in a piecewise constant form. This user's manual provides a brief overview of the mathematical model, instructions for configuration modeling and a description of the input and output data. A listing of a sample case is included.

  11. A computer program for calculating aerodynamic characteristics of low aspect-ratio wings with partial leading-edge separation

    NASA Technical Reports Server (NTRS)

    Mehrotra, S. C.; Lan, C. E.

    1978-01-01

    The necessary information for using a computer program to predict distributed and total aerodynamic characteristics for low aspect ratio wings with partial leading-edge separation is presented. The flow is assumed to be steady and inviscid. The wing boundary condition is formulated by the Quasi-Vortex-Lattice method. The leading edge separated vortices are represented by discrete free vortex elements which are aligned with the local velocity vector at midpoints to satisfy the force free condition. The wake behind the trailing edge is also force free. The flow tangency boundary condition is satisfied on the wing, including the leading and trailing edges. The program is restricted to delta wings with zero thickness and no camber. It is written in FORTRAN language and runs on CDC 6600 computer.

  12. Transonic aerodynamic characteristics of a supersonic cruise aircraft research model with the engines suspended above the wing

    NASA Technical Reports Server (NTRS)

    Mercer, C. E.; Carson, G. T., Jr.

    1979-01-01

    The influence of upper-surface nacelle exhaust flow on the aerodynamic characteristics of a supersonic cruise aircraft research configuration was investigated in a 16 foot transonic tunnel over a range of Mach numbers from 0.60 to 1.20. The arrow-wing transport configuration with engines suspended over the wing was tested at angles of attack from -4 deg to 6 deg and jet total pressure ratios from 1 to approximately 13. Wing-tip leading edge flap deflections of -10 deg to 10 deg were tested with the wing-body configuration. Various nacelle locations (chordwise, spanwise, and vertical) were tested over the ranges of Mach numbers, angles of attack, and jet total-pressure ratios. The results show that reflecting the wing-tip leading edge flap from 0 deg to -10 deg increased the maximum lift-drag ratio by 1.0 at subsonic speeds. Jet exhaust interference effects were negligible.

  13. Two-dimensional aerodynamic characteristics of several rotorcraft airfoils at Mach numbers from 0.35 to 0.90

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    An investigation was conducted in the Langley 6- by 28-inch transonic tunnel and the 6- by 19-inch transonic tunnel to determine the two-dimensional aerodynamic characteristics of several rotorcraft airfoils at Mach numbers from 0.35 to 0.90. The airfoils differed in thickness, thickness distribution, and camber. The FX69-H-098, the BHC-540, and the NACA 0012 airfoils were investigated in the 6- by 28-inch tunnel at Reynolds numbers (based on chord) from about 4.7 to 9.3 million at the lowest and highest test Mach numbers respectively. The FX69-H-098, the NLR-1, the BHC-540, and the NACA 23012 airfoils were investigated in the 6- by 19-inch tunnel at Reynolds numbers from about 0.9 to 2.2 million at the lowest and highest test Mach numbers respectively.

  14. Effect of tail size reductions on longitudinal aerodynamic characteristics of a three surface F-15 model with nonaxisymmetric nozzles

    NASA Technical Reports Server (NTRS)

    Frassinelli, Mark C.; Carson, George T., Jr.

    1990-01-01

    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of horizontal and vertical tail size reductions on the longitudinal aerodynamic characteristics of a modified F-15 model with canards and 2-D convergent-divergent nozzles. Quantifying the drag decrease at low angles of attack produced by tail size reductions was the primary focus. The model was tested at Mach numbers of 0.40, 0.90, and 1.20 over an angle of attack of -2 degree to 10 degree. The nozzle exhaust flow was simulated using high pressure air at nozzle pressure ratios varying from 1.0 (jet off) to 7.5. Data were obtained on the baseline configuration with and without tails as well as with reduced horizontal and/or vertical tail sizes that were 75, 50, and 25 percent of the baseline tail areas.

  15. Aerodynamic Characteristics of a 14-Percent-Thick NASA Supercritical Airfoil Designed for a Normal-Force Coefficient of 0.7

    NASA Technical Reports Server (NTRS)

    Harris, C. D.

    1975-01-01

    This report documents the experimental aerodynamic characteristics of a 14 percent thick supercritical airfoil based on an off design sonic pressure plateau criterion. The design normal force coefficient was 0.7. The results are compared with those of the family related 10 percent thick supercritical airfoil 33. Comparisons are also made between experimental and theoretical characteristics and composite drag rise characteristics derived for a full scale Reynolds number of 40 million.

  16. Novel Image Analysis Method for Blade Aerodynamic Performance on Operational Turbine

    NASA Astrophysics Data System (ADS)

    Swytink-Binnema, Nigel; Johnson, David A.

    2014-06-01

    Tuft flow visualisation has been used to study aerodynamic stall on wind turbine blades for several decades. In recent years, advances in the processing power of personal computers have made digital image processing vastly more accessible. In this paper, therefore, a novel method is presented to digitally analyse tuft flow visualisation on the blade of an operating wind turbine. Examination of the outboard 40% of the blade of a 10 m diameter wind turbine revealed stalled flow in wind speeds from 5m/s to 20m/s. The region of stall at those speeds increased from 5% to 40% of the coverage area of the tufts. This increase in the amount of stalled flow is expected for stall-regulated wind turbines. Overall, the results are very promising and demonstrate potential for a wide range of aerodynamics applications including real-time blade stall determination and classical wind tunnel aerodynamics studies.

  17. Longitudinal aerodynamic characteristics of a wing-winglet model designed at M = 0.8, C sub L = 0.4 using linear aerodynamic theory

    NASA Technical Reports Server (NTRS)

    Kuhlman, J. M.

    1983-01-01

    Wind tunnel test results have been presented herein for a subsonic transport type wing fitted with winglets. Wind planform was chosen to be representative of wings used on current jet transport aircraft, while wing and winglet camber surfaces were designed using two different linear aerodynamic design methods. The purpose of the wind tunnel investigation was to determine the effectiveness of these linear aerodynamic design computer codes in designing a non-planar transport configuration which would cruise efficiently. The design lift coefficient was chosen to be 0.4, at a design Mach number of 0.8. Force and limited pressure data were obtained for the basic wing, and for the wing fitted with the two different winglet designs, at Mach numbers of 0.60, 0.70, 0.75 and 0.80 over an angle of attack range of -2 to +6 degrees, at zero sideslip. The data have been presented without analysis to expedite publication.

  18. Unsteady aerodynamic characteristics of a fighter model undergoing large-amplitude pitching motions at high angles of attack

    NASA Technical Reports Server (NTRS)

    Brandon, Jay M.; Shah, Gautam H.

    1990-01-01

    The effects of harmonic or constant-rate-ramp pitching motions (giving angles of attack from 0 to 75 deg) on the aerodynamic performance of a fighter-aircraft model with highly swept leading-edge extensions are investigated experimentally in the NASA Langley 12-ft low-speed wind tunnel. The model configuration and experimental setup are described, and the results of force and moment measurements and flow visualizations are presented graphically and discussed in detail. Large force overshoots and hysteresis are observed and attributed to lags in vortical-flow development and breakup. The motion variables have a strong influence on the persistence of dynamic effects, which are found to affect pitch-rate capability more than flight-path turning performance.

  19. Wind tunnel investigation of the aerodynamic characteristics of symmetrically deflected ailerons of the F-8C airplane. [conducted in the Langley 8-foot transonic pressure tunnel

    NASA Technical Reports Server (NTRS)

    Gera, J.

    1977-01-01

    A .042-scale model of the F-8C airplane was investigated in a transonic wind tunnel at high subsonic Mach numbers and a range of angles of attack between-3 and 20 degrees. The effect of symmetrically deflected ailerons on the longitudinal aerodynamic characteristics was measured. Some data were also obtained on the lateral control effectiveness of asymmetrically deflected horizontal tail surfaces.

  20. Supersonic aerodynamic characteristics of a Sparrow 3 type missile model with wing controls and comparison with existing tail-control results

    NASA Technical Reports Server (NTRS)

    Monta, W. J.

    1977-01-01

    An experimental investigation was conducted on a model of a wing control version of the Sparrow III type missile to determine the static aerodynamic characteristics over an angle of attack range from 0 deg to 40 deg for Mach numbers from 1.50 to 4.60.

  1. F-5-L Boat Seaplane : performance characteristics

    NASA Technical Reports Server (NTRS)

    Diehl, W S

    1922-01-01

    Performance characteristics for the F-5-L Boat Seaplane are given. Characteristic curves for the RAF-6 airfoil and the F-5-L wings, parasite resistance and velocity data, engine and propeller characteristics, effective and maximum horsepower, and cruising performance are discussed.

  2. Applicability of commercial CFD tools for assessment of heavy vehicle aerodynamic characteristics.

    SciTech Connect

    Pointer, W. D.; Sofu, T.; Chang, J.; Weber, D.; Nuclear Engineering Division

    2008-12-01

    In preliminary validation studies, computational predictions from the commercial CFD codes Star-CD were compared with detailed velocity, pressure and force balance data from experiments completed in the 7 ft. by 10 ft. wind tunnel at NASA Ames using a Generic Conventional Model (GCM) that is representative of typical current-generation tractor-trailer geometries. Lessons learned from this validation study were then applied to the prediction of aerodynamic drag impacts associated with various changes to the GCM geometry, including the addition of trailer based drag reduction devices and modifications to the radiator and hood configuration. Add-on device studies have focused on ogive boat tails, with initial results indicating that a seven percent reduction in drag coefficient is easily achievable. Radiator and hood reconfiguration studies have focused on changing only the size of the radiator and angle of the hood components without changes to radii of curvature between the radiator grill and hood components. Initial results indicate that such changes lead to only modest changes in drag coefficient.

  3. Longitudinal aerodynamic characteristics of light, twin-engine, propeller-driven airplanes

    NASA Technical Reports Server (NTRS)

    Wolowicz, C. H.; Yancey, R. B.

    1972-01-01

    Representative state-of-the-art analytical procedures and design data for predicting the longitudinal static and dynamic stability and control characteristics of light, propeller-driven airplanes are presented. Procedures for predicting drag characteristics are also included. The procedures are applied to a twin-engine, propeller-driven airplane in the clean configuration from zero lift to stall conditions. The calculated characteristics are compared with wind-tunnel and flight data. Included in the comparisons are level-flight trim characteristics, period and damping of the short-period oscillatory mode, and windup-turn characteristics. All calculations are documented.

  4. Effects of nonlinear unsteady aerodynamics on performance, stability and control of an F-18 configuration

    NASA Astrophysics Data System (ADS)

    Lin, Guofeng

    Large-amplitude forced oscillation data for an F-18 configuration are analyzed with two modeling methods: Fourier functional analysis to form the indicial integrals, and a generalized dynamic aerodynamic model for stability and control analysis. The indicial integral is first applied to calculate the pitch damping parameter for comparison with the conventional forced oscillation test. It is shown that the reduced frequency affects the damping much more strongly than the test amplitude. Using the indicial integral models in a flight simulation code for an F-18 configuration, it is found that the configuration with unsteady aerodynamics becomes unstable in pitch if the pitch rate is high, in contrast to the quasi-steady configuration which depends mainly on the instantaneous angle of attack. In a pitch-up maneuver in the post-stall regime the configuration with unsteady aerodynamics can stay at a high pitch attitude and angle of attack without losing altitude for a much longer duration than the quasi-steady model. However, the speed will decrease faster because of higher drag. The newly developed generalized dynamic aerodynamic model is of the nonlinear algebraic form with the coefficients being determined from a set of large amplitude oscillatory experimental data by using least-square fitting. The resulting model coefficients are functions of the reduced frequency and amplitude. The new aerodynamic models have been verified with data in harmonic oscillation with a smaller amplitude and in constant pitch-rate motions. The new algebraic models are especially useful in stability and control analysis, and are used in bifurcation analysis and control studies for the same F-18 HARV configuration. The results show significant differences in the equilibrium surfaces and dynamic stability. It is also shown that control gains developed with the conventional quasi-steady aerodynamic data may not be adequate when the effect of unsteady aerodynamics is significant. A numerical

  5. An investigation on the aerodynamic performance of a vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Vaishnav, Etesh

    Scope and Method of Study. The two dimensional unsteady flow around a vertical axis wind turbine (VAWT) comprising three rotating symmetric airfoils (NACA0018) was studied numerically with the consideration of the near wake. The flow around the wind turbine was simulated using ANSYS FLUENT 12.0.16 at Reynolds number of 106. ICEM CFD was used as a pre-processor to generate hexahedral grid and arbitrary sliding mesh technique was implemented to create a moving mesh. SST k-o turbulence model was employed for the analysis and simulation was set to run at several tip speed ratios ranging from 1 to 5. The variation of the performance coefficient (Cp) as a function of tip speed ratio (lambda) was investigated by plotting a graph between them. A validation was made by comparing CFD results with experimental results. Maximum Cp of 0.34 was obtained at lambda of 3.8. In addition, the effect of the rotor diameter on the VAWT's performance was investigated. In this regard, rotor diameter was halved and the angular velocity was doubled to keep the tip speed ratio constant. Furthermore, the effect of laminar boundary layer separation on Cp of a VAWT was studied by comparing the results of Laminar viscous model and RANS turbulence model. Apart from that, the effect of solidity on Cp was investigated by comparing the Cp obtained from six bladed turbine with the three bladed turbine. Findings and Conclusions. Influence of rotor diameter on the aerodynamic performance of a VAWT was investigated and found that Cp remained almost constant at the same value of lambda ranging from 1 to 5. This was due to the fact that the ratio of the chord length and the rotor radius were kept the same in both cases. For Laminar flow at low Reynolds number, Cp was found to be low due to the presence of leading edge separation bubble and reduced lift-to-drag ratio. Therefore, in order to increase Cp of a VAWT at low Reynolds numbers (e.g. small VAWT), different blade geometry (e.g. cambered) and

  6. Approach to establishing the effect of aeroelasticity on aerodynamic characteristics of the space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Schlosser, D. C.; Dominik, D. F.

    1983-01-01

    The static aeroelastic effects on the longitudinal stability and elevon/aileron effectiveness of the space transportation system (STS) Space Shuttle orbiter were estimated by a simplified approach called the elevon torsional stiffness (ETS) method. This method employs rigid model wind tunnel test results to predict aeroelastic effects. Lateral/directional stability and rudder effectiveness were based on results of a wind tunnel test in which a flexible tail model was used. Comparisons with selective flight data are made in this paper. Results of correlations with flight data (although limited at the present time) verify the predicted aeroelastic effects for the orbiter. The orbiter's structural characteristics are such that the effects of aeroelasticity, whether estimated using analytical techniques or simplified methods, do not appear to affect the vehicle performance to any great extent. The large amount of scatter in the flight-extracted data made verification of the aeroelastic corrections very difficult. Generally, the simplified elevon torsional stiffness method provided better correlation with flight test results than he analytical method and reduced the verification effort and cost.

  7. Aerodynamic characteristics of a feathered dinosaur measured using physical models. Effects of form on static stability and control effectiveness.

    PubMed

    Evangelista, Dennis; Cardona, Griselda; Guenther-Gleason, Eric; Huynh, Tony; Kwong, Austin; Marks, Dylan; Ray, Neil; Tisbe, Adrian; Tse, Kyle; Koehl, Mimi

    2014-01-01

    We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, [Formula: see text]Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While [Formula: see text]M. gui lived after [Formula: see text]Archaeopteryx and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver.

  8. Aerodynamic Performance and Static Stability and Control of Flat-Top Hypersonic Gliders at Mach Numbers from 0.6 to 18

    NASA Technical Reports Server (NTRS)

    Syvertson, Clarence A; Gloria, Hermilo R; Sarabia, Michael F

    1958-01-01

    A study is made of aerodynamic performance and static stability and control at hypersonic speeds. In a first part of the study, the effect of interference lift is investigated by tests of asymmetric models having conical fuselages and arrow plan-form wings. The fuselage of the asymmetric model is located entirely beneath the wing and has a semicircular cross section. The fuselage of the symmetric model was centrally located and has a circular cross section. Results are obtained for Mach numbers from 3 to 12 in part by application of the hypersonic similarity rule. These results show a maximum effect of interference on lift-drag ratio occurring at Mach number of 5, the Mach number at which the asymmetric model was designed to exploit favorable lift interference. At this Mach number, the asymmetric model is indicated to have a lift-drag ratio 11 percent higher than the symmetric model and 15 percent higher than the asymmetric model when inverted. These differences decrease to a few percent at a Mach number of 12. In the course of this part of the study, the accuracy to the hypersonic similarity rule applied to wing-body combinations is demonstrated with experimental results. These results indicate that the rule may prove useful for determining the aerodynamic characteristics of slender configurations at Mach numbers higher than those for which test equipment is really available. In a second part of the study, the aerodynamic performance and static stability and control characteristics of a hypersonic glider are investigated in somewhat greater detail. Results for Mach numbers from 3 to 18 for performance and 0.6 to 12 for stability and control are obtained by standard text techniques, by application of the hypersonic stability rule, and/or by use of helium as a test medium. Lift-drag ratios of about 5 for Mach numbers up to 18 are shown to be obtainable. The glider studied is shown to have acceptable longitudinal and directional stability characteristics through the

  9. Transonic Aerodynamic Characteristics of Two Wedge Airfoil Sections Including Unsteady Flow Studies

    NASA Technical Reports Server (NTRS)

    Johnston, Patrick J.

    1959-01-01

    A two-dimensional wind-tunnel investigation has been conducted on a 20-percent-thick single-wedge airfoil section. Steady-state forces and moments were determined from pressure measurements at Mach numbers from 0.70 to about 1.25. Additional information on the flows about the single wedge is provided by means of instantaneous pressure measurements at Mach numbers up to unity. Pressure distributions were also obtained on a symmetrical double-wedge or diamond-shaped profile which had the same leading-edge included angle as the single-wedge airfoil. A comparison of the data on the two profiles to provide information on the effects of the afterbody showed that with the exception of drag, the single-wedge profile proved to be aerodynamically superior to the diamond profile in all respects. The lift effectiveness of the single-wedge airfoil section far exceeded that of conventional thin airfoil sections over the speed range of the investigation. Pitching-moment irregularities, caused by negative loadings near the trailing edge, generally associated with conventional airfoils of equivalent thicknesses were not exhibited by the single-wedge profile. Moderately high pulsating pressures existing over the base of the single-wedge airfoil section were significantly reduced as the Mach number was increased beyond 0.92 and the boundaries of the dead airspace at the base of the model converged to eliminate the vortex street in the wake. Increasing the leading-edge radius from 0 to 1 percent of the chord had a minor effect on the steady-state forces and generally raised the level of pressure pulsations over the forward part of the single-wedge profile.

  10. Quiet Clean Short-Haul Experimental Engine (QCSEE) Over-The-Wing (OTW) propulsion system test report. Volume 2: Aerodynamics and performance. [engine performance tests to define propulsion system performance on turbofan engines

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The design and testing of the over the wing engine, a high bypass, geared turbofan engine, are discussed. The propulsion system performance is examined for uninstalled performance and installed performance. The fan aerodynamic performance and the D nozzle and reverser thrust performance are evaluated.

  11. Aerodynamic Characteristics of SC1095 and SC1094 R8 Airfoils

    DTIC Science & Technology

    2003-12-01

    Development, and Engineering Command Ames Research Center Moffett Field, California December 2003 National Aeronautics and Space Administration Ames...60A ROTOR BLADE AND AIRFOILS ................................................................................... 2 EVALUATION OF SECTION CHARACTERISTICS...Characteristics of SC1095 and SC1094 R8 Airfoils WILLIAM G. BOUSMAN Aeroflightdynamics Directorate U.S. Army Research, Development, and Engineering Command Ames

  12. Low-speed aerodynamic characteristics of a 16-percent-thick variable-geometry airfoil designed for general aviation applications

    NASA Technical Reports Server (NTRS)

    Barnwell, R. W.; Noonan, K. W.; Mcghee, R. J.

    1978-01-01

    Tests were conducted in the Langley low-turbulence pressure tunnel to determine the aerodynamic characteristics of climb, cruise, and landing configurations. These tests were conducted over a Mach number range from 0.10 to 0.35, a chord Reynolds number range from 2.0 x 1 million to 20.0 x 1 million, and an angle-of-attack range from -8 deg to 20 deg. Results show that the maximum section lift coefficients increased in the Reynolds number range from 2.0 x 1 million to 9.0 x 1 million and reached values of approximately 2.1, 1.8, and 1.5 for the landing, climb, and cruise configurations, respectively. Stall characteristics, although of the trailing-edge type, were abrupt. The section lift-drag ratio of the climb configuration with fixed transition near the leading edge was about 78 at a lift coefficient of 0.9, a Mach number of 0.15, and a Reynolds number of 4.0 x 1 million. Design lift coefficients of 0.9 and 0.4 for the climb and cruise configurations were obtained at the same angle of attack, about 6 deg, as intended. Good agreement was obtained between experimental results and the predictions of a viscous, attached-flow theoretical method.

  13. Effect of Ground Proximity on the Aerodynamic Characteristics of Aspect-Ratio-1 Airfoils With and Without End Plates

    NASA Technical Reports Server (NTRS)

    Carter, Arthur W.

    1961-01-01

    An investigation has been made to determine the effect of ground proximity on the aerodynamic characteristics of aspect-ratio-1 airfoils. The investigation was made with the model moving over the water in a towing tank in order to eliminate the effects of wind-tunnel walls and of boundary layer on ground boards at small ground clearances. The results indicated that, as the ground was approached, the airfoils experienced an increase in lift-curve slope and a reduction in induced drag; thus, lift-drag ratio was increased. As the ground was approached, the profile drag remained essentially constant for each airfoil. Near the ground, the addition of end plates to the airfoil resulted in a large increase in lift-drag ratio. The lift characteristics of the airfoils indicated stability of height at positive angles of attack and instability of height at negative angles; therefore, the operating range of angles of attack would be limited to positive values. At positive angles of attack, the static longitudinal stability was increased as the height above the ground was reduced. Comparison of the experimental data with Wieselsberger's ground-effect theory (NACA Technical Memorandum 77) indicated generally good agreement between experiment and theory for the airfoils without end plates.

  14. Two-dimensional aerodynamic characteristics of several polygon-shaped cross-sectional models applicable to helicopter fuselages

    NASA Technical Reports Server (NTRS)

    Kelley, Henry L.; Crowell, Cynthia A.; Wilson, John C.

    1992-01-01

    A wind-tunnel investigation was conducted to determine 2-D aerodynamic characteristics of nine polygon-shaped models applicable to helicopter fuselages. The models varied from 1/2 to 1/5 scale and were nominally triangular, diamond, and rectangular in shape. Side force and normal force were obtained at increments of angle of flow incidence from -45 to 90 degrees. The data were compared with results from a baseline UH-60 tail-boom cross-section model. The results indicate that the overall shapes of the plots of normal force and side force were similar to the characteristic shape of the baseline data; however, there were important differences in magnitude. At a flow incidence of 0 degrees, larger values of normal force for the polygon models indicate an increase in fuselage down load of 1 to 2.5 percent of main-rotor thrust compared with the baseline value. Also, potential was indicated among some of the configurations to produce high fuselage side forces and yawing moments compared with the baseline model.

  15. The aerodynamic characteristics of eight very thick airfoils from tests in the variable density wind tunnel

    NASA Technical Reports Server (NTRS)

    Jacobs, Eastman N

    1932-01-01

    Report presents the results of wind tunnel tests on a group of eight very thick airfoils having sections of the same thickness as those used near the roots of tapered airfoils. The tests were made to study certain discontinuities in the characteristic curves that have been obtained from previous tests of these airfoils, and to compare the characteristics of the different sections at values of the Reynolds number comparable with those attained in flight. The discontinuities were found to disappear as the Reynolds number was increased. The results obtained from the large-scale airfoil, a symmetrical airfoil having a thickness ratio of 21 per cent, has the best general characteristics.

  16. Aerodynamic performance of a drag reduction device on a full-scale tractor/trailer

    NASA Astrophysics Data System (ADS)

    Lanser, Wendy R.; Ross, James C.; Kaufman, Andrew E.

    1991-09-01

    The effectiveness of an aerodynamic boattail on a tractor/trailer road vehicle was measured in the NASA Ames Research Center 80- by 120-Foot Wind Tunnel. Results are examined for the tractor/trailer with and without the drag reduction device. Pressure measurements and flow visualization show that the aerodynamic boattail traps a vortex or eddy in the corner formed between the device and the rear corner of the trailer. This recirculating flow turns the flow inward as it separates from the edges of the base of the trailer. This modified flow behavior increases the pressure acting over the base area of the truck, thereby reducing the net aerodynamic drag of the vehicle. Drag measurements and pressure distributions in the region of the boattail device are presented for selected configurations. The optimum configuration reduces the overall drag of the tractor/trailer combination by about 10 percent at a zero yaw angle. Unsteady pressure measurements do not indicate strong vortex shedding, although the addition of the boattail plates increases high frequency content of the fluctuating pressure.

  17. Aerodynamic performance of a drag reduction device on a full-scale tractor/trailer

    NASA Technical Reports Server (NTRS)

    Lanser, Wendy R.; Ross, James C.; Kaufman, Andrew E.

    1991-01-01

    The effectiveness of an aerodynamic boattail on a tractor/trailer road vehicle was measured in the NASA Ames Research Center 80- by 120-Foot Wind Tunnel. Results are examined for the tractor/trailer with and without the drag reduction device. Pressure measurements and flow visualization show that the aerodynamic boattail traps a vortex or eddy in the corner formed between the device and the rear corner of the trailer. This recirculating flow turns the flow inward as it separates from the edges of the base of the trailer. This modified flow behavior increases the pressure acting over the base area of the truck, thereby reducing the net aerodynamic drag of the vehicle. Drag measurements and pressure distributions in the region of the boattail device are presented for selected configurations. The optimum configuration reduces the overall drag of the tractor/trailer combination by about 10 percent at a zero yaw angle. Unsteady pressure measurements do not indicate strong vortex shedding, although the addition of the boattail plates increases high frequency content of the fluctuating pressure.

  18. Aerodynamic Characteristics of NACA 23012 and 23021 Airfoils with 20-Percent-chord External-Airfoil Flaps of NACA 23012 Section

    NASA Technical Reports Server (NTRS)

    Platt, Robert C; Abbott, Ira H

    1937-01-01

    Report presents the results of an investigation of the general aerodynamic characteristics of the NACA 23012 and 23021 airfoils, each equipped with a 0.20c external flap of NACA 23012 section. The tests were made in the NACA 7 by 10-foot and variable-density wind tunnels and covered a range of Reynolds numbers that included values corresponding to those for landing conditions of a wide range of airplanes. Besides a determination of the variation of lift and drag characteristics with position of the flap relative to the main airfoil, complete aerodynamic characteristics of the airfoil-flap combination with a flap hinge axis selected to give small hinge moments were measured in the two tunnels. Some measurements of air loads on the flap itself in the presence of the wing were made in the 7 by 10-foot wind tunnel.

  19. Effects of wing shape, aspect ratio and deviation angle on aerodynamic performance of flapping wings in hover

    NASA Astrophysics Data System (ADS)

    Shahzad, Aamer; Tian, Fang-Bao; Young, John; Lai, Joseph C. S.

    2016-11-01

    This numerical study is focused on assessing the effect on the aerodynamic hovering performance of wing shapes defined by the radius of the first moment of the wing area ( r 1 ¯ ) and aspect ratio (AR). In addition, the effect of introducing a deviation angle in the kinematics is examined. The performance of r 1 ¯ = 0 . 43 , 0.53, and 0.63 wings with AR of 1.5, 2.96, 4.5, and 6.0 is investigated at Reynolds numbers (Re) = 12, 400, and 13 500. The performance trends of the wing shapes have been observed to be independent of Re for both 2-angle and 3-angle kinematics. This is because high suction pressures associated with the leading-edge vortex are predominantly spread in the distal (away from the wing root) and leeward regions (towards the trailing-edge) of high flapping velocities for all the cases. While the deviation angle is detrimental to the production of lift and power economy (PE, defined as the ratio of the mean lift coefficient to the mean aerodynamic power coefficient) at Re = 12 due to strong viscous effects, it improves PE at Re = 400 and 13 500. A high instantaneous angle of attack at the stroke reversal results in high lift peak for 3-angle kinematics but its effect at Re = 400 and 13 500 is attenuated by strong vortical structures on the underside of the wing. Maximum PE is achieved at AR = 2.96, as a low AR wing does not produce enough lift and high AR wings consume more aerodynamic power. Although the lift is maximized using high r 1 ¯ and AR wings, our results show that low r 1 ¯ and high AR wings are best for maximizing PE for a given lift in insects.

  20. Evaluating the catching performance of aerodynamic rain gauges through field comparisons and CFD modelling

    NASA Astrophysics Data System (ADS)

    Pollock, Michael; Colli, Matteo; Stagnaro, Mattia; Lanza, Luca; Quinn, Paul; Dutton, Mark; O'Donnell, Greg; Wilkinson, Mark; Black, Andrew; O'Connell, Enda

    2016-04-01

    Accurate rainfall measurement is a fundamental requirement in a broad range of applications including flood risk and water resource management. The most widely used method of measuring rainfall is the rain gauge, which is often also considered to be the most accurate. In the context of hydrological modelling, measurements from rain gauges are interpolated to produce an areal representation, which forms an important input to drive hydrological models and calibrate rainfall radars. In each stage of this process another layer of uncertainty is introduced. The initial measurement errors are propagated through the chain, compounding the overall uncertainty. This study looks at the fundamental source of error, in the rainfall measurement itself; and specifically addresses the largest of these, the systematic 'wind-induced' error. Snowfall is outside the scope. The shape of a precipitation gauge significantly affects its collection efficiency (CE), with respect to a reference measurement. This is due to the airflow around the gauge, which causes a deflection in the trajectories of the raindrops near the gauge orifice. Computational Fluid-Dynamic (CFD) simulations are used to evaluate the time-averaged airflows realized around the EML ARG100, EML SBS500 and EML Kalyx-RG rain gauges, when impacted by wind. These gauges have a similar aerodynamic profile - a shape comparable to that of a champagne flute - and they are used globally. The funnel diameter of each gauge, respectively, is 252mm, 254mm and 127mm. The SBS500 is used by the UK Met Office and the Scottish Environmental Protection Agency. Terms of comparison are provided by the results obtained for standard rain gauge shapes manufactured by Casella and OTT which, respectively, have a uniform and a tapered cylindrical shape. The simulations were executed for five different wind speeds; 2, 5, 7, 10 and 18 ms-1. Results indicate that aerodynamic gauges have a different impact on the time-averaged airflow patterns

  1. Lateral-directional aerodynamic characteristics of light, twin-engine, propeller driven airplanes

    NASA Technical Reports Server (NTRS)

    Wolowicz, C. H.; Yancey, R. B.

    1972-01-01

    Analytical procedures and design data for predicting the lateral-directional static and dynamic stability and control characteristics of light, twin engine, propeller driven airplanes for propeller-off and power-on conditions are reported. Although the consideration of power effects is limited to twin engine airplanes, the propeller-off considerations are applicable to single engine airplanes as well. The procedures are applied to a twin engine, propeller driven, semi-low-wing airplane in the clean configuration through the linear lift range. The calculated derivative characteristics are compared with wind tunnel and flight data. Included in the calculated characteristics are the spiral mode, roll mode, and Dutch roll mode over the speed range of the airplane.

  2. Aerodynamic characteristics of a large scale model with a swept wing and augmented jet flap

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Koenig, D. G.

    1971-01-01

    Data of tests of a large-scale swept augmentor wing model in the 40- by 80-foot wind tunnel are presented. The data includes longitudinal characteristics with and without a horizontal tail as well as results of preliminary investigation of lateral-directional characteristics. The augmentor flap deflection was varied from 0 deg to 70.6 deg at isentropic jet thrust coefficients of 0 to 1.47. The tests were made at a Reynolds number from 2.43 to 4.1 times one million.

  3. Aerodynamic characteristics of seven symmetrical airfoil sections through 180-degree angle of attack for use in aerodynamic analysis of vertical axis wind turbines

    SciTech Connect

    Sheldahl, R E; Klimas, P C

    1981-03-01

    When work began on the Darrieus vertical axis wind turbine (VAWT) program at Sandia National Laboratories, it was recognized that there was a paucity of symmetrical airfoil data needed to describe the aerodynamics of turbine blades. Curved-bladed Darrieus turbines operate at local Reynolds numbers (Re) and angles of attack (..cap alpha..) seldom encountered in aeronautical applications. This report describes (1) a wind tunnel test series conducted at moderate values of Re in which 0 less than or equal to ..cap alpha.. less than or equal to 180/sup 0/ force and moment data were obtained for four symmetrical blade-candidate airfoil sections (NACA-0009, -0012, -0012H, and -0015), and (2) how an airfoil property synthesizer code can be used to extend the measured properties to arbitrary values of Re (10/sup 4/ less than or equal to Re less than or equal to 10/sup 7/) and to certain other section profiles (NACA-0018, -0021, -0025).

  4. Performance characteristics of STIS detectors

    NASA Technical Reports Server (NTRS)

    Stern, Robert A.

    1992-01-01

    We report quantum efficiency measurements of back-illuminated, ion-implanted, laser-annealed charge coupled devices (CCD's) in the wavelength range 13-10,000 A. The equivalent quantum efficiency (EQE = effective photons detected per incident photon) ranges from a minimum of 5 percent as 1216 A to a maximum of 87 percent at 135 A. Using a simple relationship for the charge collection efficiency of the CCD pixels as a function of depth, we present a semi-empirical model with few parameters which reproduces our measurements with a fair degree of accuracy. The advantage of this model is that is can be used to predict CCD QE performance for shallow backside implanted devices without detailed solution of a system of differential equations, as in conventional approaches, and yields a simple analytic form for the charge collection efficiency which is adequate for detector calibration purposes. Making detailed assumptions about the dopant profile, we also solve the carrier density and continuity equations in order to relate our semi-empirical model parameters to surface and bulk device properties. The latter procedure helps to better establish device processing parameters for a given level of CCD QE performance.

  5. The Effects of a Highly Cambered Low-Drag Wing and of Auxiliary Flaps on the High-Speed Aerodynamic Characteristics of a Twin-Engine Pursuit Airplane Model

    NASA Technical Reports Server (NTRS)

    Ganzer, Victor M

    1944-01-01

    Results are presented for tests of two wings, an NACA 230-series wing and a highly-cambered NACA 66-series wing on a twin-engine pursuit airplane. Auxiliary control flaps were tested in combinations with each wing. Data showing comparison of high-speed aerodynamic characteristics of the model when equipped with each wing, the effect of the auxiliary control flaps on aerodynamic characteristics, and elevator effectiveness for the model with the 66-series wing are presented. High-speed aerodynamic characteristics of the model were improved with the 66-series wing.

  6. Aerodynamic performance of two-dimensional, chordwise flexible flapping wings at fruit fly scale in hover flight.

    PubMed

    Sridhar, Madhu; Kang, Chang-kwon

    2015-05-06

    Fruit flies have flexible wings that deform during flight. To explore the fluid-structure interaction of flexible flapping wings at fruit fly scale, we use a well-validated Navier-Stokes equation solver, fully-coupled with a structural dynamics solver. Effects of chordwise flexibility on a two dimensional hovering wing is studied. Resulting wing rotation is purely passive, due to the dynamic balance between aerodynamic loading, elastic restoring force, and inertial force of the wing. Hover flight is considered at a Reynolds number of Re = 100, equivalent to that of fruit flies. The thickness and density of the wing also corresponds to a fruit fly wing. The wing stiffness and motion amplitude are varied to assess their influences on the resulting aerodynamic performance and structural response. Highest lift coefficient of 3.3 was obtained at the lowest-amplitude, highest-frequency motion (reduced frequency of 3.0) at the lowest stiffness (frequency ratio of 0.7) wing within the range of the current study, although the corresponding power required was also the highest. Optimal efficiency was achieved for a lower reduced frequency of 0.3 and frequency ratio 0.35. Compared to the water tunnel scale with water as the surrounding fluid instead of air, the resulting vortex dynamics and aerodynamic performance remained similar for the optimal efficiency motion, while the structural response varied significantly. Despite these differences, the time-averaged lift scaled with the dimensionless shape deformation parameter γ. Moreover, the wing kinematics that resulted in the optimal efficiency motion was closely aligned to the fruit fly measurements, suggesting that fruit fly flight aims to conserve energy, rather than to generate large forces.

  7. Effects of bending-torsional duct-induced swirl distortion on aerodynamic performance of a centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Hou, Hongjuan; Wang, Leilei; Wang, Rui; Yang, Yanzhao

    2017-04-01

    A turbocharger compressor working in commercial vehicles, especially in some passenger cars, often works together with some pipes with complicated geometry as an air intake system, due to limit of available space in internal combustion engine compartments. These pipes may generate various distortions of physical parameters of the air at the inlet of the compressor and therefore the compressor aerodynamic performance deteriorates. Sometimes, the turbocharging engine fails to work at some operation points. This paper investigates the effects of various swirl distortions induced by different bending-torsional intake ducts on the aerodynamic performance of a turbocharger compressor by both 3D numerical simulations and experimental measurements. It was found that at the outlet of the pipes the different inlet ducts can generate different swirl distortions, twin vortices and bulk-like vortices with different rotating directions. Among them, the bulk-like vortices not only affect seriously the pressure distribution in the impeller domain, but also significantly deteriorate the compressor performance, especially at high flow rate region. And the rotating direction of the bulk-like vortices is also closely associated with the efficiency penalty. Besides the efficiency, the transient flow rate through a single impeller channel, or the asymmetric mass flow crossing the whole impeller, can be influenced by two disturbances. One is from the upstream bending-torsional ducts; other one is from the downstream volute.

  8. Numerical investigation of the aerodynamic performance for the newly designed cavity vane type vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Suffer, K. H.; Usubamatov, R.; Quadir, G. A.; Ismail, K. A.

    2015-05-01

    Research and development activities in the field of renewable energy, especially wind and solar, have been considerably increased, due to the worldwide energy crisis and high global emission. However, the available technical designs are not yet adequate to develop a reliable distributed wind energy converter for low wind speed conditions. The last few years have proved that Vertical Axis Wind Turbines (VAWTs) are more suitable for urban areas than Horizontal Axis Wind Turbines (HAWTs). To date, very little has been published in this area to assess good performance and lifetime of VAWTs either in open or urban areas. The power generated by vertical axis wind turbines is strongly dependent on the aerodynamic performance of the turbines. The main goal of this current research is to investigate numerically the aerodynamic performance of a newly designed cavity type vertical axis wind turbine. In the current new design the power generated depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. For numerical investigation, commercially available computational fluid dynamic (CFD) software GAMBIT and FLUENT were used. In this numerical analysis the Shear Stress Transport (SST) k-ω turbulence model is used which is better than the other turbulence models available as suggested by some researchers. The computed results show good agreement with published experimental results.

  9. Aerodynamic design optimization of a fuel efficient high-performance, single-engine, business airplane

    NASA Technical Reports Server (NTRS)

    Holmes, B. J.

    1980-01-01

    A design study has been conducted to optimize a single-engine airplane for a high-performance cruise mission. The mission analyzed included a cruise speed of about 300 knots, a cruise range of about 1300 nautical miles, and a six-passenger payload (5340 N (1200 lb)). The purpose of the study is to investigate the combinations of wing design, engine, and operating altitude required for the mission. The results show that these mission performance characteristics can be achieved with fuel efficiencies competitive with present-day high-performance, single- and twin-engine, business airplanes. It is noted that relaxation of the present Federal Aviation Regulation, Part 23, stall-speed requirement for single-engine airplanes facilitates the optimization of the airplane for fuel efficiency.

  10. Effects of empennage surface location on aerodynamic characteristics of a twin-engine afterbody model with nonaxisymmetric nozzles

    NASA Technical Reports Server (NTRS)

    Capone, Francis J.; Carson, George T., Jr.

    1985-01-01

    An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of empennage surface location and vertical tail cant angle on the aft-end aerodynamic characteristics of a twin-engine fighter-type configuration. The configuration featured two-dimensional convergent-divergent nozzles and twin-vertical tails. The investigation was conducted with different empennage locations that included two horizontal and three vertical tail positions. Vertical tail cant angle was varied from -10 deg to 20 deg for one selected configuration. Tests were conducted at Mach number 0.60 to 1.20 and at angles of attack -3 to 9 deg. Nozzle pressure ratio was varied from jet off to approximately 9, depending upon Mach number. Tail interference effects were present throughout the range of Mach numbers tested and found to be either favorable or adverse, depending upon test condition and model configuration. At a Mach number of 0.90, adverse interference effects accounted for a significant percentage of total aft-end drag. Interference effects on the nozzle were generally favorable but became adverse as the horizontal tails were moved from a mid to an aft position. The configuration with nonaxisymmetric nozzles had lower total aft-end drag with tails-off than a similar configuration with axisymmetric nozzles at Mach numbers of 0.60 and 0.90.

  11. Aerodynamic characteristics of two rotorcraft airfoils designed for application to the inboard region of a main rotor blade

    NASA Technical Reports Server (NTRS)

    Noonan, Kevin W.

    1990-01-01

    A wind tunnel investigation was conducted to determine the 2-D aerodynamic characteristics of two new rotorcraft airfoils designed especially for application to the inboard region of a helicopter main rotor blade. The two new airfoils, the RC(4)-10 and RC(5)-10, and a baseline airfoil, the VR-7, were all studied in the Langley Transonic Tunnel at Mach nos. from about 0.34 to 0.84 and at Reynolds nos. from about 4.7 to 9.3 x 10 (exp 6). The VR-7 airfoil had a trailing edge tab which is deflected upwards 4.6 degs. In addition, the RC(4)-10 airfoil was studied in the Langley Low Turbulence Pressure Tunnel at Mach nos. from 0.10 to 0.44 and at Reynolds nos. from 1.4 to 5.4 x 10 (exp 6) respectively. Some comparisons were made of the experimental data for the new airfoils and the predictions of two different theories. The results of this study indicates that both of the new airfoils offer advantages over the baseline airfoil. These advantages are discussed.

  12. Two-Dimensional Shape Optimization of Hypersonic Vehicles Considering Transonic Aerodynamic Performance

    NASA Astrophysics Data System (ADS)

    Ueno, Atsushi; Suzuki, Kojiro

    For the success of hypersonic vehicles, their shape must be optimized to achieve a high lift-to-drag ratio as well as a low aerodynamic heating rate in the hypersonic regime. In addition, the transonic lift-to-drag ratio must also be optimized to realize quick acceleration to the hypersonic cruise speed. The three-dimensional lift-to-drag ratio can be improved even by the two-dimensional section shape (i.e., airfoil) optimization in the region where the sweep back angle is small. Here, prior to three-dimensional shape optimization, a study is done to optimize airfoils of hypersonic vehicles based on these three parameters. At optimization, the hypersonic lift-to-drag ratio is maximized while the transonic lift-to-drag ratio and the aerodynamic heating rate are constrained. The optimum lift coefficient for hypersonic cruise at the maximum lift-to-drag ratio is investigated. The relation between the leading edge radius, which determines the aerodynamic heating rate, and the hypersonic lift-to-drag ratio is also investigated. Results show that to improve the hypersonic lift-to-drag ratio, the airfoil thickness around the leading edge should be small as long as an appropriate compromise with the transonic lift-to-drag ratio is achieved. Results also show that the optimum lift coefficient for hypersonic cruise is much lower than that for typical supersonic vehicles. Small cruise lift coefficient suggests that the wing loading of a hypersonic vehicle should be small. The leading edge radius should be determined by a compromise between the hypersonic lift-to-drag ratio and leading edge heating. Airfoil optimization can provide an appropriate initial guess of the three-dimensional optimum shape. By using an appropriate initial guess, the computation time of the three-dimensional shape optimization is expected to be reduced.

  13. Longitudinal aerodynamic characteristics of an elliptical body with a horizontal tail at Mach numbers from 2.3 to 4.63

    NASA Technical Reports Server (NTRS)

    Shrout, B. L.; Robins, A. W.

    1982-01-01

    Longitudinal aerodynamic characteristics of a configuration consisting of an elliptical body with an in plane horizontal tail were investigated. The tests were conducted at Mach numbers of 2.3, 2.96, 4.0, and 4.63. In some cases, the configuration with negative tail deflections yielded higher values of maximum lift drag ratio than did the configuration with an undeflected tail. This was due to body upwash acting on the tail and producing an additional lift increment with essentially no drag penalty. Linear theory methods used to estimate some of the longitudinal aerodynamic characteristics of the model yielded results which compared well with experimental data for all Mach numbers in this investigation and for both small angles of attack and larger angles of attack where nonlinear (vortex) flow phenomena were present.

  14. Aerodynamic investigations of a disc-wing

    NASA Astrophysics Data System (ADS)

    Dumitrache, Alexandru; Frunzulica, Florin; Grigorescu, Sorin

    2017-01-01

    The purpose of this paper is to evaluate the aerodynamic characteristics of a wing-disc, for a civil application in the fire-fighting system. The aerodynamic analysis is performed using a CFD code, named ANSYS Fluent, in the flow speed range up to 25 m/s, at lower and higher angle of attack. The simulation is three-dimensional, using URANS completed by a SST turbulence model. The results are used to examine the flow around the disc with increasing angle of attack and the structure of the wake.

  15. Investigation of the influence of wind shear on the aerodynamic characteristics of aircraft using a vortex-lattice method

    NASA Technical Reports Server (NTRS)

    Vicroy, Dan D.

    1988-01-01

    The objective was to investigate and characterize the aerodynamic effect of shear flow through a series of sensitivity studies of the wind velocity gradients and wing planform geometry parameters. The wind shear effect was computed using a modified vortex-lattice computer program and characterized through the formulation of wind shear aerodynamic coefficients. The magnitude of the aerodynamic effect was demonstrated by computing the resultant change in the aerodynamics of a conventional wing and tail combination on a fixed flight path through a simulated microburst. The results of the study indicate that a significant amount of the control authority of an airplane may be required to counteract the wind shear induced forces and moments in the microburst environment.

  16. Complementary Aerodynamic Performance Datasets for Variable Speed Power Turbine Blade Section from Two Independent Transonic Turbine Cascades

    NASA Technical Reports Server (NTRS)

    Flegel, Ashlie B.; Welch, Gerard E.; Giel, Paul W.; Ames, Forrest E.; Long, Jonathon A.

    2015-01-01

    Two independent experimental studies were conducted in linear cascades on a scaled, two-dimensional mid-span section of a representative Variable Speed Power Turbine (VSPT) blade. The purpose of these studies was to assess the aerodynamic performance of the VSPT blade over large Reynolds number and incidence angle ranges. The influence of inlet turbulence intensity was also investigated. The tests were carried out in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility and at the University of North Dakota (UND) High Speed Compressible Flow Wind Tunnel Facility. A large database was developed by acquiring total pressure and exit angle surveys and blade loading data for ten incidence angles ranging from +15.8deg to -51.0deg. Data were acquired over six flow conditions with exit isentropic Reynolds number ranging from 0.05×106 to 2.12×106 and at exit Mach numbers of 0.72 (design) and 0.35. Flow conditions were examined within the respective facility constraints. The survey data were integrated to determine average exit total-pressure and flow angle. UND also acquired blade surface heat transfer data at two flow conditions across the entire incidence angle range aimed at quantifying transitional flow behavior on the blade. Comparisons of the aerodynamic datasets were made for three "match point" conditions. The blade loading data at the match point conditions show good agreement between the facilities. This report shows comparisons of other data and highlights the unique contributions of the two facilities. The datasets are being used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.

  17. Supersonic aerodynamic characteristics of a lifting-body orbiter model with a blunted delta planform at Mach 2.30 to 4.60

    NASA Technical Reports Server (NTRS)

    Blair, A. B., Jr.

    1972-01-01

    An investigation has been made in the Langley Unitary Plan wind tunnel to determine the aerodynamic characteristics of a lifting-body orbiter model with a blunted delta planform. The model was tested at Mach numbers from 2.30 to 4.60, at nominal angles of attack from -4 deg to 60 deg and angles of sideslip from -4 deg to 10 deg, and at a Reynolds number of 2.5 million per foot.

  18. The Effect of Blade-Section Thickness Ratio on the Aerodynamic Characteristics of Related Full-Scale Propellers at Mach Numbers up to 0.65

    NASA Technical Reports Server (NTRS)

    Maynard, Julian D; Steinberg, Seymour

    1953-01-01

    The results of an investigation of two 10-foot-diameter, two-blade NACA propellers are presented for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. These results are compared with those from previous investigations of five related NACA propellers in order to evaluate the effects of blade-section thickness ratios on propeller aerodynamic characteristics.

  19. Wind Tunnel Investigation at Low Speed of Aerodynamic Characteristics of Army Chemical Corps Model E-112 Bomblets with Span Chord Ratio of 2 - 1

    NASA Technical Reports Server (NTRS)

    Letko, W.

    1956-01-01

    An experimental investigation has been made in the Langley stability tunnel to determine the aerodynamic characteristics of the Army Chemical Corps model E-112 bomblets with span-chord ratio of 2:1. A detailed analysis has not been made; however, the results showed that all the models were spirally unstable and that a large gap between the model tips and end plates tended to reduce the instability.

  20. Effect of twist and camber on the low-speed aerodynamic characteristics of a powered close-coupled wing-canard configuration

    NASA Technical Reports Server (NTRS)

    Paulson, J. W., Jr.; Thomas, J. L.

    1978-01-01

    A series of wind-tunnel tests were conducted in a V/STOL tunnel to determine the low-speed longitudinal aerodynamic characteristics of a powered close-coupled wing/canard fighter configuration. The data was obtained for a high angle-of-attack maneuvering configuration and a takeoff and landing configuration. The data presented in tabulated form are intended for reference purposes.

  1. Supersonic aerodynamic characteristics of a low-aspect-ratio missile model with wing and tail controls and with tails in line and interdigitated

    NASA Technical Reports Server (NTRS)

    Graves, E. B.

    1972-01-01

    A study has been made to determine the aerodynamic characteristics of a low-aspect ratio cruciform missile model with all-movable wings and tails. The configuration was tested at Mach numbers from 1.50 to 4.63 with the wings in the vertical and horizontal planes and with the wings in a 45 deg roll plane with tails in line and interdigitated.

  2. Calculation of Aerodynamic Loading and Twist Characteristics of a Flexible Wing at Mach Numbers Approaching 1.0 and Comparison with Experiment

    NASA Technical Reports Server (NTRS)

    Mugler, John P., Jr.

    1960-01-01

    An iteration method is presented by which the detailed aerodynamic loading and twist characteristics of a flexible wing with known elastic properties may be calculated. The method is applicable at Mach numbers approaching 1.0 as well as at subsonic Mach numbers. Calculations were made for a wing-body combination; the wing was swept back 45 deg and had an aspect ratio of 4. Comparisons were made with experimental results at Mach numbers from.0.80 to 0.98.

  3. Static aerodynamic characteristics of a winged single-stage-to-orbit vehicle at Mach numbers from 0.3 to 4.63

    NASA Technical Reports Server (NTRS)

    Freeman, D. C., Jr.; Fournier, R. H.

    1978-01-01

    The Langley 8 foot transonic pressure tunnel and the Langley Unitary Plan wind tunnel used to determine the longitudinal and lateral-directional aerodynamic characteristics of a winged single-state-to-orbit vehicle was investigated. The model was tested over a Mach number range from 0.3 to 4.63 for an angle-of-attack range from 4 to 30 D at both 0 and 5 D sideslip.

  4. Low-speed aerodynamic characteristics of a 14-percent-thick NASA phase 2 supercritical airfoil designed for a lift coefficient of 0.7

    NASA Technical Reports Server (NTRS)

    Harris, C. D.; Mcghee, R. J.; Allison, D. O.

    1980-01-01

    The low speed aerodynamic characteristics of a 14 percent thick supercritical airfoil are documented. The wind tunnel test was conducted in the Low Turbulence Pressure Tunnel. The effects of varying chord Reynolds number from 2,000,000 to 18,000,000 at a Mach number of 0.15 and the effects of varying Mach number from 0.10 to 0.32 at a Reynolds number of 6,000,000 are included.

  5. Summary of low-speed aerodynamic characteristics of upper-surface-blown jet-flap configurations

    NASA Technical Reports Server (NTRS)

    Phelps, A. E., III; Johnson, J. L., Jr.; Margason, R. J.

    1976-01-01

    The results of recent wind tunnel investigations to provide fundamental information on the upper surface blown (USB) jet flap concept demonstrated that the USB concept provides good high-lift performance. It is shown that the low speed performance is dependent upon the jet turning angle and turning efficiency and on the use of proper leading and trailing edge treatment to prevent premature flow separation. The best means of achieving good turning performance in any particular USB application must be determined from overall operational considerations in which high speed performance, structures and noise, as well as low speed performance, are evaluated. The large diving moments generated at high lift coefficients can be trimmed satisfactorily with a large, conventional horizontal tail; a high tail position is best from longitudinal stability considerations. Large rolling and yawing moments are introduced with the loss of an engine, but these moments can be trimmed satisfactorily through the use of asymmetrical boundary layer control and through the use of spoiler and rudder deflection as needed.

  6. Aerodynamic challenges of ALT

    NASA Technical Reports Server (NTRS)

    Hooks, I.; Homan, D.; Romere, P. O.

    1985-01-01

    The approach and landing test (ALT) of the Space Shuttle Orbiter presented a number of unique challenges in the area of aerodynamics. The purpose of the ALT program was both to confirm the use of the Boeing 747 as a transport vehicle for ferrying the Orbiter across the country and to demonstrate the flight characteristics of the Orbiter in its approach and landing phase. Concerns for structural fatigue and performance dictated a tailcone be attached to the Orbiter for ferry and for the initial landing tests. The Orbiter with a tailcone attached presented additional challenges to the normal aft sting concept of wind tunnel testing. The landing tests required that the Orbiter be separated from the 747 at approximately 20,000 feet using aerodynamic forces to fly the vehicles apart. The concept required a complex test program to determine the relative effects of the two vehicles on each other. Also of concern, and tested, was the vortex wake created by the 747 and the means for the Orbiter to avoid it following separation.

  7. The role of free stream turbulence and blade surface conditions on the aerodynamic performance of wind turbine blades

    NASA Astrophysics Data System (ADS)

    Maldonado, Victor Hugo

    Wind turbines operate within the atmospheric boundary layer (ABL) which gives rise to turbulence among other flow phenomena. There are several factors that contribute to turbulent flow: The operation of wind turbines in two layers of the atmosphere, the surface layer and the mixed layer. These layers often have unstable wind conditions due to the daily heating and cooling of the atmosphere which creates turbulent thermals. In addition, wind turbines often operate in the wake of upstream turbines such as in wind farms; where turbulence generated by the rotor can be compounded if the turbines are not sited properly. Although turbulent flow conditions are known to affect performance, i.e. power output and lifespan of the turbine, the flow mechanisms by which atmospheric turbulence and other external conditions (such as blade debris contamination) adversely impact wind turbines are not known in enough detail to address these issues. The main objectives of the current investigation are thus two-fold: (i) to understand the interaction of the turbulent integral length scales and surface roughness on the blade and its effect on aerodynamic performance, and (ii) to develop and apply flow control (both passive and active) techniques to alleviate some of the adverse fluid dynamics phenomena caused by the atmosphere (i.e. blade contamination) and restore some of the aerodynamic performance loss. In order to satisfy the objectives of the investigation, a 2-D blade model based on the S809 airfoil for horizontal axis wind turbine (HAWT) applications was manufactured and tested at the Johns Hopkins University Corrsin Stanley Wind Tunnel facility. Additional levels of free stream turbulence with an intensity of 6.14% and integral length scale of about 0.321 m was introduced into the flow via an active grid. The free stream velocity was 10 m/s resulting in a Reynolds number based on blade chord of Rec ≃ 2.08x105. Debris contamination on the blade was modeled as surface roughness

  8. Effect of wing flexibility on the experimental aerodynamic characteristics of an oblique wing

    NASA Technical Reports Server (NTRS)

    Hopkins, E. J.; Yee, S. C.

    1977-01-01

    A solid-aluminum oblique wing was designed to deflect considerably under load so as to relieve the asymmetric spanwise stalling that is characteristic of this type of wing by creating washout on the trailing wing panel and washin on the leading wing panel. Experimental forces, and pitching, rolling and yawing moments were measured with the wing mounted on a body of revolution. In order to vary the dynamic pressure, measurements were made at several unit Reynolds numbers, and at Mach numbers. The wing was investigated when unswept (at subsonic Mach numbers only) and when swept 45 deg, 50 deg, and 60 deg. The wing was straight tapered in planform, had an aspect ratio of 7.9 (based on the unswept span), and a profile with a maximum thickness of 4 percent chord. The results substantiate the concept that an oblique wing designed with the proper amount of flexibility self relieves itself of asymmetric spanwise stalling and the associated nonlinear moment curves.

  9. Aerodynamic characteristics of the HL-20 and HL-20A lifting-body configurations

    NASA Technical Reports Server (NTRS)

    Ware, George M.; Spencer, Bernard, Jr.; Micol, John R.

    1991-01-01

    The data show that the HL-20 is longitudinally and laterally stable over the test range from Mach 10 to 0.2. At hypersonic speeds it has a trimmed lift/drag ratio of 1.4. This values gives the vehicle a cross range capability similar to that of the Space Shuttle. At subsonic speeds, the HL-20 has a trimmed lift/drag ratio of about 3.6. Replacing the flat plate outboard fins with fins having an airfoil shape, increased the maximum trimmed L/D to 4.3. Preliminary evaluation of configuration modifications (the HL-20A series), indicates that trim at higher values of lift at hypersonic speeds could be achieved with an L/D of about 1.0. In the supersonic range, the lift and directional stability characteristics were improved. The untrimmed subsonic L/D was increased to 5.8 with airfoil fins.

  10. Supersonic aerodynamic characteristics of a series of wrap-around-fin missile configurations

    NASA Technical Reports Server (NTRS)

    Fournier, R. H.

    1977-01-01

    A parametric study of wrap-around-fin missile configurations was conducted at Mach numbers from 1.60 to 2.86 in the Langley Unitary Plan wind tunnel. The fin configurations investigated included variations in chord length, leading edge sweep, thickness ratio, and leading edge shape. The investigation also included a smooth and a stepped-down afterbody required for flush retraction of the wrap-around-fin configuration. The investigation indicated no unusual longitudinal characteristics; however, all the wrap-around-fin configurations tested indicated erratic lateral behavior, particularly in the form of induced roll at zero angle of attack and irregular variations of roll with angle of attack and Mach number. The magnitude of rolling moment at an angle of attack of 0 deg is estimated to represent approximately 0.25 deg or less roll control deflection. The stepped-down afterbody has a marked effect on reducing the induced roll.

  11. A program to compute three-dimensional subsonic unsteady aerodynamic characteristics using the doublet lattic method, L216 (DUBFLX). Volume 1: Engineering and usage

    NASA Technical Reports Server (NTRS)

    Richard, M.; Harrison, B. A.

    1979-01-01

    The program input presented consists of configuration geometry, aerodynamic parameters, and modal data; output includes element geometry, pressure difference distributions, integrated aerodynamic coefficients, stability derivatives, generalized aerodynamic forces, and aerodynamic influence coefficient matrices. Optionally, modal data may be input on magnetic file (tape or disk), and certain geometric and aerodynamic output may be saved for subsequent use.

  12. Aerodynamic Design Using Neural Networks

    NASA Technical Reports Server (NTRS)

    Rai, Man Mohan; Madavan, Nateri K.

    2003-01-01

    The design of aerodynamic components of aircraft, such as wings or engines, involves a process of obtaining the most optimal component shape that can deliver the desired level of component performance, subject to various constraints, e.g., total weight or cost, that the component must satisfy. Aerodynamic design can thus be formulated as an optimization problem that involves the minimization of an objective function subject to constraints. A new aerodynamic design optimization procedure based on neural networks and response surface methodology (RSM) incorporates the advantages of both traditional RSM and neural networks. The procedure uses a strategy, denoted parameter-based partitioning of the design space, to construct a sequence of response surfaces based on both neural networks and polynomial fits to traverse the design space in search of the optimal solution. Some desirable characteristics of the new design optimization procedure include the ability to handle a variety of design objectives, easily impose constraints, and incorporate design guidelines and rules of thumb. It provides an infrastructure for variable fidelity analysis and reduces the cost of computation by using less-expensive, lower fidelity simulations in the early stages of the design evolution. The initial or starting design can be far from optimal. The procedure is easy and economical to use in large-dimensional design space and can be used to perform design tradeoff studies rapidly. Designs involving multiple disciplines can also be optimized. Some practical applications of the design procedure that have demonstrated some of its capabilities include the inverse design of an optimal turbine airfoil starting from a generic shape and the redesign of transonic turbines to improve their unsteady aerodynamic characteristics.

  13. Aerodynamic Assessment of Flight-Determined Subsonic Lift and Drag Characteristics of Seven Lifting-Body and Wing-Body Reentry Vehicle Configurations

    NASA Technical Reports Server (NTRS)

    Saltzman, Edwin J.; Wang, K. Charles; Iliff, Kenneth W.

    2002-01-01

    This report examines subsonic flight-measured lift and drag characteristics of seven lifting-body and wing-body reentry vehicle configurations with truncated bases. The seven vehicles are the full-scale M2-F1, M2-F2, HL-10, X-24A, X-24B, and X-15 vehicles and the Space Shuttle Enterprise. Subsonic flight lift and drag data of the various vehicles are assembled under aerodynamic performance parameters and presented in several analytical and graphical formats. These formats are intended to unify the data and allow a greater understanding than individually studying the vehicles allows. Lift-curve slope data are studied with respect to aspect ratio and related to generic wind-tunnel model data and to theory for low-aspect-ratio platforms. The definition of reference area is critical for understanding and comparing the lift data. The drag components studied include minimum drag coefficient, lift-related drag, maximum lift-to drag ratio, and, where available, base pressure coefficients. The influence of forebody drag on afterbody and base drag at low lift is shown to be related to Hoerner's compilation for body, airfoil, nacelle, and canopy drag. This feature may result in a reduced need of surface smoothness for vehicles with a large ratio of base area to wetted area. These analyses are intended to provide a useful analytical framework with which to compare and evaluate new vehicle configurations of the same generic family.

  14. Subsonic aerodynamic characteristic of semispan commercial transport model with wing-mounted advanced ducted propeller operating in reverse thrust. [conducted in the Langley 14 by 22 foot subsonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Applin, Zachary T.; Jones, Kenneth M.; Gile, Brenda E.; Quinto, P. Frank

    1994-01-01

    A test was conducted in the Langley 14 by 22 Foot Subsonic Tunnel to determine the effect of the reverse-thrust flow field of a wing-mounted advanced ducted propeller on the aerodynamic characteristics of a semispan subsonic high-lift transport model. The advanced ducted propeller (ADP) model was mounted separately in position alongside the wing so that only the aerodynamic interference of the propeller and nacelle affected the aerodynamic performance of the transport model. Mach numbers ranged from 0.14 to 0.26; corresponding Reynolds numbers ranged from 2.2 to 3.9 x 10(exp 6). The reverse-thrust flow field of the ADP shielded a portion of the wing from the free-stream airflow and reduced both lift and drag. The reduction in lift and drag was a function of ADP rotational speed and free-stream velocity. Test results included ground effects data for the transport model and ADP configuration. The ground plane caused a beneficial increase in drag and an undesirable slight increase in lift. The ADP and transport model performance in ground effect was similar to performance trends observed for out of ground effect. The test results form a comprehensive data set that supports the application of the ADP engine and airplane concept on the next generation of advanced subsonic transports. Before this investigation, the engine application was predicted to have detrimental ground effect characteristics. Ground effect test measurements indicated no critical problems and were the first step in proving the viability of this engine and airplane configuration.

  15. In-flight measurements of the GA/W/-2 aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Gregorek, G. M.; Hoffmann, M. J.; Weislogel, G. S.; Vogel, G. M.

    1977-01-01

    Flight tests of a new 13% General Aviation Airfoil - the GA(W)-2 - gloved full span onto the existing wing of a Beech Sundowner have generated chordwise pressure distributions and wake surveys. Section lift, drag and moment coefficients derived from these measurements verify wind tunnel data and theory predicting the performance of this airfoil. The effect of steps, rivets and surface coatings upon the drag of the GA(W)-2 was also evaluated.

  16. Low-speed aerodynamic characteristics of an airfoil optimized for maximum lift coefficient

    NASA Technical Reports Server (NTRS)

    Bingham, G. J.; Chen, A. W.

    1972-01-01

    An investigation has been conducted in the Langley low-turbulence pressure tunnel to determine the two-dimensional characteristics of an airfoil optimized for maximum lift coefficient. The design maximum lift coefficient was 2.1 at a Reynolds number of 9.7 million. The airfoil with a smooth surface and with surface roughness was tested at angles of attack from 6 deg to 26 deg, Reynolds numbers (based on airfoil chord) from 2.0 million to 12.9 million, and Mach numbers from 0.10 to 0.35. The experimental results are compared with values predicted by theory. The experimental pressure distributions observed at angles of attack up to at least 12 deg were similar to the theoretical values except for a slight increase in the experimental upper-surface pressure coefficients forward of 26 percent chord and a more severe gradient just behind the minimum-pressure-coefficient location. The maximum lift coefficients were measured with the model surface smooth and, depending on test conditions, varied from 1.5 to 1.6 whereas the design value was 2.1.

  17. Aerodynamic Characteristics of a Canard and an Outboard-Tail Airplane Model at High Subsonic Speeds

    NASA Technical Reports Server (NTRS)

    Fournier, Paul G.

    1961-01-01

    An investigation has been made in the Langley high-speed 7- by 10-foot tunnel through a range of Mach numbers from 0.60 to 0.95 of the static longitudinal and lateral stability and control characteristics of a canard airplane configuration and an outboard-tail configuration. The canard model had a twisted wing with approximately 67 deg of sweepback and an aspect ratio of 2.91 and was tested with three trapezoidal canard surfaces having ratios of exposed area to wing area of 0.032, 0.076, and 0.121. The canard model had a single body-mounted vertical tail. The outboard-tail model had its horizontal- and vertical-tail surfaces mounted on slender bodies attached to the wing tips and located to the rear and outboard of the 67 deg sweptback wing of aspect ratio 1.00. The data, which are presented with limited analysis, provide information at high subsonic speeds on these two types of high-speed airplanes which have previously been tested at supersonic speeds and reported in NACA RM L58BO7 and NACA RM L58E20.

  18. Theoretical and Experimental Comparison of Aerodynamic Characteristics for Flexible Membrane Wings with Cambered Frames

    NASA Astrophysics Data System (ADS)

    Wrist, Andrew; Hubner, James

    2015-11-01

    Flexible membrane wings of the MAV (micro air vehicle) scale can experience improved lift/drag ratios, delays in stall, and decreased time-averaged flow separation when compared to rigid wings. Previous research examined the effect of frame camber on the time-averaged shapes of membrane wings and observed that increasing frame camber results in increased aero-induced membrane camber. This study involves a more in-depth DIC (Digital Image Correlation) analysis of the previous research to increase the understanding of the time-averaged shapes for membrane wings with cambered frames and offers a theoretical comparison to the experimental results. The author performed a theoretical lifting-line analysis based on the time-averaged shape for the membrane wings to calculate lift, induced drag, and circulation. The calculations include the effects of geometric twist, aspect ratio, and effective angle-of-attack. The wings, with an aspect ratio of 2, were fabricated with silicone rubber membranes and 3D printed cambered frames differing in percent camber, maximum camber location, and thickness. The DIC images were acquired in The University of Alabama's MAV wind tunnel as tests were performed at 10 m/s (Re = 50,000). The analysis will be discussed in the presentation. Graduate Research Assistant.

  19. Modulating flow and aerodynamic characteristics of a square cylinder in crossflow using a rear jet injection

    NASA Astrophysics Data System (ADS)

    Huang, Rong F.; Hsu, Ching M.; Chen, Yu T.

    2017-01-01

    The temporally evolved flow behaviors around a square cylinder subject to modulation of a planar jet issued from the cylinder's downstream surface into the wake were studied using the laser-assisted smoke flow visualization method and synchronized hot-wire anemometers. The drag force asserted on the square cylinder was obtained by measuring the surface pressures. Four characteristic flow modes (wake-dominated, transitional, critical, and jet-dominated) were observed in different regimes of freestream Reynolds number and jet injection ratio. In the wake-dominated mode, the jet swung periodically back and forth on the downstream surface due to the wake vortex shedding. In the transitional mode, the vortex shedding in the wake vanished so that the flow around the cylinder presented no periodic oscillations. In the critical mode, the wake width became smaller and therefore made the vortex shedding frequency larger than that observed in the wake dominated mode. In the jet-dominated mode, the jet had a large momentum that entrained wake fluids and therefore stabilized the instabilities of the wake, separated boundary layers on lateral surfaces, and stagnation point on the upstream surface. Two standing vortices appeared in the near wake beside the high-momentum jet. The width of the wake was decreased substantially by jet entrainment. The drag coefficient decreased with an increase in the jet injection ratio. The downstream surface jet injection caused the pressure coefficients to decrease at the upstream surface and to increase at the downstream surface. Therefore, the drag coefficients were decreased significantly by 26%, 33%, and 38% at the injection ratios of 0.5, 1.5, and 2.5, respectively.

  20. High supersonic aerodynamic characteristics of five irregular planform wings with systematically varying wing fillet geometry tested in the NASA/LaRC 4-foot UPWT (LEG 2) (LA45A/B)

    NASA Technical Reports Server (NTRS)

    1976-01-01

    An experimental and analytical aerodynamic program to develop predesign guides for irregular planform wings is reported. The benefits are linearization of subsonic lift curve slope to high angles of attack and avoidance of subsonic pitch instabilities at high lift by proper tailoring of the planform fillet wing combination while providing the desired hypersonic trim angle and stability. The two prime areas of concern are to optimize shuttle orbiter landing and entry characteristics. Basic longitudinal aerodynamic characteristics at high supersonic speeds are developed.

  1. Aerodynamic Performance and Static Stability at Mach Number 3.3 of an Aircraft Configuration Employing Three Triangular Wing Panels and a Body Equal Length

    NASA Technical Reports Server (NTRS)

    James, Carlton S.

    1960-01-01

    An aircraft configuration, previously conceived as a means to achieve favorable aerodynamic stability characteristics., high lift-drag ratio, and low heating rates at high supersonic speeds., was modified in an attempt to increase further the lift-drag ratio without adversely affecting the other desirable characteristics. The original configuration consisted of three identical triangular wing panels symmetrically disposed about an ogive-cylinder body equal in length to the root chord of the panels. This configuration was modified by altering the angular disposition of the wing panels, by reducing the area of the panel forming the vertical fin, and by reshaping the body to produce interference lift. Six-component force and moment tests of the modified configuration at combined angles of attack and sideslip were made at a Mach number of 3.3 and a Reynolds number of 5.46 million. A maximum lift-drag ratio of 6.65 (excluding base drag) was measured at a lift coefficient of 0.100 and an angle of attack of 3.60. The lift-drag ratio remained greater than 3 up to lift coefficient of 0.35. Performance estimates, which predicted a maximum lift-drag ratio for the modified configuration 27 percent greater than that of the original configuration, agreed well with experiment. The modified configuration exhibited favorable static stability characteristics within the test range. Longitudinal and directional centers of pressure were slightly aft of the respective centroids of projected plan-form and side area.

  2. Summary analysis of the Gemini entry aerodynamics

    NASA Technical Reports Server (NTRS)

    Whitnah, A. M.; Howes, D. B.

    1972-01-01

    The aerodynamic data that were derived in 1967 from the analysis of flight-generated data for the Gemini entry module are presented. These data represent the aerodynamic characteristics exhibited by the vehicle during the entry portion of Gemini 2, 3, 5, 8, 10, 11, and 12 missions. For the Gemini, 5, 8, 10, 11, and 12 missions, the flight-generated lift-to-drag ratios and corresponding angles of attack are compared with the wind tunnel data. These comparisons show that the flight generated lift-to-drag ratios are consistently lower than were anticipated from the tunnel data. Numerous data uncertainties are cited that provide an insight into the problems that are related to an analysis of flight data developed from instrumentation systems, the primary functions of which are other than the evaluation of flight aerodynamic performance.

  3. An investigation of the aerodynamic characteristics of a new general aviation airfoil in flight

    NASA Technical Reports Server (NTRS)

    Gregorek, G. M.; Hoffmann, M. J.; Weislogel, G. S.

    1982-01-01

    A low speed airfoil, the GA(W)-2, - a 13% thickness to chord ratio airfoil was evaluated. The wing of a Beech Sundowner was modified at by adding balsa ribs and covered with aluminum skin, to alter the existing airfoil shape to that of the GA(W)-2 airfoil. The aircraft was flown in a flight test program that gathered wing surface pressures and wake data from which the lift drag, and pitching moment of the airfoil could be determined. After the base line performance of the airfoil was measured, the drag due to surface irregularities such as steps, rivets and surface waviness was determined. The potential reduction of drag through the use of surface coatings such as KAPTON was also investigated.

  4. Prediction of static aerodynamic characteristics for slender bodies alone and with lifting surfaces to very high angles of attack

    NASA Technical Reports Server (NTRS)

    Jorgensen, L. H.

    1977-01-01

    An engineering-type method is presented for computing normal-force and pitching-moment coefficients for slender bodies of circular and noncircular cross section alone and with lifting surfaces. In this method, a semi-empirical term representing viscous-separation crossflow is added to a term representing potential-theory crossflow. For many bodies of revolution, computed aerodynamic characteristics are shown to agree with measured results for investigated free-stream Mach numbers from 0.6 to 2.9. The angles of attack extend from 0 deg to 180 deg for M = 2.9 from 0 deg to 60 deg for M = 0.6 to 2.0. For several bodies of elliptic cross section, measured results are also predicted reasonably well over the investigated Mach number range from 0.6 to 2.0 and at angles of attack from 0 deg to 60 deg. As for the bodies of revolution, the predictions are best for supersonic Mach numbers. For body-wing and body-wing-tail configurations with wings of aspect ratios 3 and 4, measured normal-force coefficients and centers are predicted reasonably well at the upper test Mach number of 2.0. Vapor-screen and oil-flow pictures are shown for many body, body-wing and body-wing-tail configurations. When spearation and vortex patterns are asymmetric, undesirable side forces are measured for the models even at zero sideslip angle. Generally, the side-force coefficients decrease or vanish with the following: increase in Mach number, decrease in nose fineness ratio, change from sharp to blunt nose, and flattening of body cross section (particularly the body nose).

  5. Prediction of static aerodynamic characteristics for slender bodies alone and with lifting surfaces to very high angles of attack

    NASA Technical Reports Server (NTRS)

    Jorgensen, L. H.

    1976-01-01

    An engineering-type method is presented for computing normal-force and pitching-moment coefficients for slender bodies of circular and noncircular cross section alone and with lifting surfaces. In this method, a semi-empirical term representing viscous-separation crossflow is added to a term representing potential-theory crossflow. For many bodies of revolution, computed aerodynamic characteristics are shown to agree with measured results for investigated free-stream Mach numbers from 0.6 to 2.9. For several bodies of elliptic cross section, measured results are also predicted reasonably well over the investigated Mach number range from 0.6 to 2.0 and at angles of attack from 0 to 60 deg. As for the bodies of revolution, the predictions are best for supersonic Mach numbers. For body-wing and body-wing-tail configurations with wings of aspect ratios 3 and 4, measured normal-force coefficients and centers are predicted reasonably well at the upper test Mach number of 2.0. However, with a decrease in Mach number to 0.6, the agreement for C sub N rapidly deteriorates, although the normal-force centers remain in close agreement. Vapor-screen and oil-flow pictures are shown for many body, body-wing, and body-wing-tail configurations. When separation and vortex patterns are asymmetric, undesirable side forces are measured for the models even at zero sideslip angle. Generally, the side-force coefficients decrease or vanish with the following: increase in Mach number, decrease in nose fineness ratio, change from sharp to blunt nose, and flattening of body cross section (particularly the body nose).

  6. Two-dimensional aerodynamic characteristics of three rotorcraft airfoils at Mach numbers from 0.35 to 0.90

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    Three airfoils designed for helicopter rotor application were investigated in the Langley 6- by 28-inch Transonic Tunnel to determine the two dimensional aerodynamic characteristics at Mach numbers from 0.34 to 0.88 and respective Reynolds numbers from about 4.4 x 10(6) power to 9.5 x 10(6) power. The airfoils have thickness-to-chord ratios of 0.08, 0.10, and 0.12. Trailing-edge reflex was applied to minimize pitching moment. The maximum normal-force coefficient of the RC(3)-12 airfoil is from 0.1 to 0.2 higher, depending on Mach number M, than that of the NACA 0012 airfoil tested in the same facility. The maximum normal-force coefficient of the RC(3)-10 is about equal to that of the NACA 0012 at Mach numbers to 0.40 and is higher than that of the NACA 0012 at Mach numbers above 0.40. The maximum normal force coefficient of the RC(3)-08 is about 0.19 lower than that of the NACA 0012 at a Mach number of 0.35 and about 0.05 lower at a Mach number of 0.54. The drag divergence Mach number of the RC(3)-08 airfoil at normal-force coefficients below 0.1 was indicated to be greater than the maximum test Mach number of 0.88. At zero lift, the drag-divergence Mach numbers of the RC(3)-12 and the RC(3)-10 are about 0.77 and 0.82, respectively.

  7. Subsonic aerodynamic characteristics of the HL-20 lifting-body configuration

    NASA Technical Reports Server (NTRS)

    Ware, George M.; Cruz, Christopher I.

    1993-01-01

    The HL-20 is proposed as a possible future manned spacecraft. The configuration consists of a low-aspect-ratio body with a flat undersurface. Three fins (a small centerline fin and two outboard (tip) fins set at a dihedral angle of 50 deg) are mounted on the aft body. The control system consists of elevon surfaces on the outboard fins, a set of four body flaps on the upper and lower aft body, and an all-movable center fin. Both the elevons and body flaps were capable of trimming the model to angles of attack from -2 deg to above 20 deg. The maximum trimmed lift-drag ratio was 3.6. Replacing the flat-plate tip fins with airfoil tip fins increased the maximum trimmed lift-drag ratio to 4.2. The elevons were effective as a roll control, but they produced about as much yawing moment as rolling moment because of the tip-fin dihedral angle. The body flaps produced less rolling moment than the elevons and only small values of yawing moment. A limited investigation of the effect of varying tip-fin dihedral angle indicated that a dihedral angle of 50 deg was a reasonable compromise for longitudinal and lateral stability, longitudinal trim, and performance at subsonic speeds.

  8. Aerodynamic characteristics of an all-body hypersonic aircraft configuration at Mach numbers from 0.65 to 10.6

    NASA Technical Reports Server (NTRS)

    Nelms, W. P., Jr.; Thomas, C. L.

    1971-01-01

    Aerodynamic characteristics of a model designed to represent an all body, hypersonic cruise aircraft are presented for Mach numbers from 0.65 to 10.6. The configuration had a delta planform with an elliptic cone forebody and an afterbody of elliptic cross section. Detailed effects of varying angle of attack (-2 to +15 deg), angle of sideslip (-2 to +8 deg), Mach number, and configuration buildup were considered. In addition, the effectiveness of horizontal tail, vertical tail, and canard stabilizing and control surfaces was investigated. The results indicate that all configurations were longitudinally stable near maximum lift drag ratio. The configurations with vertical tails were directionally stable at all angles of attack. Trim penalties were small at hypersonic speeds for a center of gravity location representative of the airplane, but because of the large rearward travel of the aerodynamic center, trim penalties were severe at transonic Mach numbers.

  9. Low-speed aerodynamic characteristics from wind-tunnel tests of a large-scale advanced arrow-wing supersonic-cruise transport concept

    NASA Technical Reports Server (NTRS)

    Smith, P. M.

    1978-01-01

    Tests have been conducted to extend the existing low speed aerodynamic data base of advanced supersonic-cruise arrow wing configurations. Principle configuration variables included wing leading-edge flap deflection, wing trailing-edge flap deflection, horizontal tail effectiveness, and fuselage forebody strakes. A limited investigation was also conducted to determine the low speed aerodynamic effects due to slotted training-edge flaps. Results of this investigation demonstrate that deflecting the wing leading-edge flaps downward to suppress the wing apex vortices provides improved static longitudinal stability; however, it also results in significantly reduced static directional stability. The use of a selected fuselage forebody strakes is found to be effective in increasing the level of positive static directional stability. Drooping the fuselage nose, which is required for low-speed pilot vision, significantly improves the later-directional trim characteristics.

  10. On the Aerodynamic Characteristics over Idealized Two-Dimensional Urban Street Canyon Models

    NASA Astrophysics Data System (ADS)

    Leung, K. K.; Liu, C. H.

    2012-04-01

    There are numerous anthropogenic pollutant sources in the atmospheric boundary layer (ABL) nowadays, which mainly attributed to human activities in urban areas. Hence, how urban morphology affects the heat and mass transfer in built environment is a popular research problem in the urban climate community. However, our understanding of street-level transport processes is rather limited. Laboratory experiments often serve as complementary solutions to modeling results. Although there are laboratory results available for the mass transfer over idealized urban roughness, the transport processes are not examined in details. In this paper, we attempt to demystify the pollutant removal mechanism from urban areas to the urban ABL. Laboratory measurements, which were conducted in the wind tunnel in Mechanical Engineering, The University of Hong Kong, and computational fluid dynamics (CFD) is used concurrently. The spatial air pollutant transport from the street region to the urban ABL was represented by means of water evaporation method from the soaked filter paper applied on the surfaces of the building facades and ground surface. Street canyon models of building-height-to-street-width (aspect) ratios in the range of 0.125 to 2 are carried out. The local mass transfer velocity along the street canyons was measured and archived a good comparison with the outside literature. Besides, both the laboratory and CFD results show that the pollutant removal from 2D street canyons increases with decreasing ARs. It arrives a local maximum then decreases thereafter. In the comparison between laboratory and CFD results, the difference in the size of the street canyon models, also known as scaling effects, is needed to be considered. Therefore, despite of representing the transfer behavior by the local pollutant exchange rate, scaled local/overall pollutant removal coefficient is proposed for a comparison of pollutant removal performance in a more reasonable manner. Such effect is found

  11. Optimization of rotor blades for combined structural, performance, and aeroelastic characteristics

    NASA Technical Reports Server (NTRS)

    Peters, David A.; Cheng, Y. P.

    1989-01-01

    The strategies whereby helicopter rotor blades can be optimized for combined structural, inertial, dynamic, aeroelastic, and aerodynamic performance characteristics are outlined. There are three key ingredients in the successful execution of such an interdisciplinary optimization. The first is the definition of a satisfactory performance index that combines all aspects of the problem without too many constraints. The second element is the judicious choice of computationally efficient analysis tools for the various quantitative components in both the cost functional and constraints. The third element is an effective strategy for combining the various disciplines either in parallel or sequential optimizations.

  12. Effects of wing leading-edge deflection on the low-speed aerodynamic characteristics of a low-aspect-ratio highly swept arrow-wing configuration

    NASA Technical Reports Server (NTRS)

    Coe, P. L., Jr.; Weston, R. P.

    1978-01-01

    Wing leading-edge deflection effects on the low-speed aerodynamic characteristics of a low-aspect-ratio highly swept arrow-wing configuration were determined. Static force tests were conducted in a V/STOL tunnel at a Reynolds number of about 2.5 x 1 million for an angle-of-attack range from -10 deg to 17 deg and an angle-of-sideslip range from -5 deg to 5 deg. Limited flow visualization studies were also conducted in order to provide a qualitative assessment of leading-edge upwash characteristics.

  13. Effects of upper-surface blowing and thrust vectoring on low-speed aerodynamic characteristics of a large-scale supersonic transport model

    NASA Technical Reports Server (NTRS)

    Coe, P. L., Jr.; Mclemore, H. C.; Shivers, J. P.

    1975-01-01

    Tests were conducted in the Langley full-scale tunnel to determine the low-speed aerodynamic characteristics of a large-scale arrow-wing supersonic transport configured with engines mounted above the wing for upper surface blowing, and conventional lower surface engines with provisions for thrust vectoring. A limited number of tests were conducted for the upper surface engine configuration in the high lift condition for beta = 10 in order to evaluate lateral directional characteristics, and with the right engine inoperative to evaluate the engine out condition.

  14. The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.; Podboy, Gary, G.; Woodward, Richard P.; Jeracki, Robert, J.

    2013-01-01

    The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from

  15. Investigation of Active Flow Control to Improve Aerodynamic Performance of Oscillating Wings

    NASA Technical Reports Server (NTRS)

    Narducci, Robert P.; Bowersox, Rodney; Bussom, Richard; McVeigh, Michael; Raghu, Surya; White, Edward

    2014-01-01

    The objective of this effort is to design a promising active flow control concept on an oscillating airfoil for on-blade alleviation of dynamic stall. The concept must be designed for a range of representative Mach numbers (0.2 to 0.5) and representative reduced frequency characteristics of a full-scale rotorcraft. Specifications for a sweeping-jet actuator to mitigate the detrimental effects of retreating blade stall experienced by edgewise rotors in forward flight has been performed. Wind tunnel modifications have been designed to accommodate a 5x6 test section in the Oran W. Nicks Low Speed Wind Tunnel at Texas A&M University that will allow the tunnel to achieve Mach 0.5. The flow control design is for a two-dimensional oscillating VR-7 blade section with a 15- inch chord at rotor-relevant flow conditions covering the range of reduced frequencies from 0.0 to 0.15 and Mach numbers from 0.2 to 0.5. A Computational Fluid Dynamics (CFD) analysis has been performed to influence the placement of the flow control devices for optimal effectiveness.

  16. Navier-Stokes simulations of the Shuttle Orbiter aerodynamic characteristics with emphasis on pitch trim and bodyflap

    NASA Technical Reports Server (NTRS)

    Weilmuenster, K. J.; Gnoffo, Peter A.; Greene, Francis A.

    1993-01-01

    An analysis of the longitudinal aerodynamics of the Shuttle Orbiter in the hypersonic flight regime is made through the use of computational fluid dynamics (CFD). Particular attention is given to establishing the cause of the 'pitching moment anomaly' which occurred on the Orbiter's first flight and to computing the aerodynamics of a complete Orbiter configuration at flight conditions. Data from ground based facilities as well as Orbiter flight data are used to validate the computed results. Analysis shows that the 'pitching moment anomaly' is a real gas chemistry effect which cannot be simulated in ground-based facilities. Computed flight aerodynamics for the Orbiter are within 5 percent of the measured flight values and trim bodyflap deflections are predicted to within 10 percent.

  17. Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

    NASA Technical Reports Server (NTRS)

    Hughes, Christoper E.; Gazzaniga, John A.

    2013-01-01

    A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

  18. Experimental aerodynamic characteristics of a generic hypersonic accelerator configuration at Mach numbers 1.5 and 2.0. [conducted in the Langley Unitary Plan Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Walker, Ira J.; Covell, Peter F.; Forrest, Dana K.

    1993-01-01

    An experimental investigation of the static longitudinal and lateral-directional aerodynamic characteristics of a generic hypersonic research vehicle was conducted in the Langley Unitary Plan Wind Tunnel (UPWT). A parametric study was performed to determine the interference effects of various model components. Configuration variables included delta and trapezoidal canards; large and small centerline-mounted vertical tails, along with a set of wing-mounted vertical tails; and a set of model noses with different degrees of bluntness. Wing position was varied by changing the longitudinal location and the incidence angle. The test Mach numbers were 1.5 and 2.0 at Reynolds numbers of 1 x 10(exp 6) per foot, 2 x 10(exp 6) per foot, and 4 x 10(exp 6) per foot. Angle of attack was varied from -4 degrees to 27 degrees, and sideslip angle was varied from -8 degrees to 8 degrees. Generally, the effect of Reynolds number did not deviate from conventional trends. The longitudinal stability and lift-curve slope decreased with increasing Mach number. As the wing was shifted rearward, the lift-curve slope decreased and the longitudinal stability increased. Also, the wing-mounted vertical tails resulted in a more longitudinally stable configuration. In general, the lift-drag ratio was not significantly affected by vertical-tail arrangement. The best lateral-directional stability was achieved with the large centerline-mounted tail, although the wing-mounted vertical tails exhibited the most favorable characteristics at the higher angles of attack.

  19. Effect of underwing aft-mounted nacelles on the longitudinal aerodynamic characteristics of a high-wing transport airplane

    NASA Technical Reports Server (NTRS)

    Abeyounis, W. K.; Patterson, J. C., Jr.

    1985-01-01

    As part of a propulsion/airframe integration program, tests were conducted in the Langley 16-Foot Transonic Tunnel to determine the longitudinal aerodynamic effects of installing flow through engine nacelles in the aft underwing position of a high wing transonic transfer airplane. Mixed flow nacelles with circular and D-shaped inlets were tested at free stream Mach numbers from 0.70 to 0.85 and angles of attack from -2.5 deg to 4.0 deg. The aerodynamic effects of installing antishock bodies on the wing and nacelle upper surfaces as a means of attaching and supporting nacelles in an extreme aft position were investigated.

  20. Flight effects on the aerodynamic and acoustic characteristics of inverted profile coannular nozzles, volume 1. [supersonic cruise aircraft research wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Kozlowski, H.; Packman, A. B.

    1978-01-01

    Jet noise spectra obtained at static conditions from an acoustic wind tunnel and an outdoor facility are compared. Data curves are presented for (1) the effect of relative velocity on OASPL directivity (all configurations); (2) the effect of relative velocity on noise spectra (all configurations); (3) the effect of velocity on PNL directivity (coannular nozzle configurations); (4) nozzle exhaust plume velocity profiles; and (5) the effect of relative velocity on aerodynamic performance.

  1. Study of aerodynamic technology for VSTOL fighter/attack aircraft, phase 1

    NASA Technical Reports Server (NTRS)

    Driggers, H. H.

    1978-01-01

    A conceptual design study was performed of a vertical attitude takeoff and landing (VATOL) fighter/attack aircraft. The configuration has a close-coupled canard-delta wing, side two-dimensional ramp inlets, and two augmented turbofan engines with thrust vectoring capability. Performance and sensitivities to objective requirements were calculated. Aerodynamic characteristics were estimated based on contractor and NASA wind tunnel data. Computer simulations of VATOL transitions were performed. Successful transitions can be made, even with series post-stall instabilities, if reaction controls are properly phased. Principal aerodynamic uncertainties identified were post-stall aerodynamics, transonic aerodynamics with thrust vectoring and inlet performance in VATOL transition. A wind tunnel research program was recommended to resolve the aerodynamic uncertainties.

  2. Aerodynamic Characteristics of Controls.

    DTIC Science & Technology

    1979-09-01

    Aerospace Company D -3300 Braunschweig, Germany Mail Stop 41-18 PO Box 3999 Stattle, WA 98124, USA PANEL EXECUTIVE Robert H.Rollins I1 CONTENTS Page...vz _a [ + O U = O d When the Mach ntmber comes near I or exceeds 3 nonlinear terms of the full potential equation have to be taken into account...potential flow about arbitrary bodies. In: D . Ki chemann et al: SMI-TH, A.M.O. Progress in Aeronautical Sciences, Vol. 8, Pergamon Press, Oxford, 1967, p. 1

  3. Simulation and experiment research of aerodynamic performance of small axial fans with struts

    NASA Astrophysics Data System (ADS)

    Chu, Wei; Lin, Peifeng; Zhang, Li; Jin, Yingzi; Wang, Yanping; Kim, Heuy Dong; Setoguchi, Toshiaki

    2016-06-01

    Interaction between rotor and struts has great effect on the performance of small axial fan systems. The small axial fan systems are selected as the studied objects in this paper, and four square struts are downstream of the rotor. The cross section of the struts is changed to the cylindrical shapes for the investigation: one is in the same hydraulic diameter as the square struts and another one is in the same cross section as the square struts. Influence of the shape of the struts on the static pressure characteristics, the internal flow and the sound emission of the small axial fans are studied. Standard K-ɛ turbulence model and SIMPLE algorithm are applied in the calculation of the steady fluid field, and the curves of the pressure rising against the flow rate are obtained, which demonstrates that the simulation results are in nice consistence with the experimental data. The steady calculation results are set as the initial field in the unsteady calculation. Large eddy simulation and PISO algorithm are used in the transient calculation, and the Ffowcs Williams-Hawkings model is introduced to predict the sound level at the eight monitoring points. The research results show that: the static pressure coefficients of the fan with cylindrical struts increase by about 25% compared to the fan with square struts, and the efficiencies increase by about 28.6%. The research provides a theoretical guide for shape optimization and noise reduction of small axial fan with struts.

  4. Thermic diode performance characteristics and design manual

    NASA Technical Reports Server (NTRS)

    Bernard, D. E.; Buckley, S.

    1979-01-01

    Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.

  5. Low-speed aerodynamic characteristics of a highly swept arrow wing configuration with several deflected leading edge concepts

    NASA Technical Reports Server (NTRS)

    Gentry, G. L., Jr.; Coe, P. L., Jr.

    1980-01-01

    The effectiveness of leading edge concepts for minimizing or controlling leading edge flow separation was studied. Emphasis was placed on low speed performance, stability, and control characteristics of configurations with highly swept wings. Simple deflection of the leading edge, a variable camber leading edge system, and a leading edge vortex flow system were among the concepts studied. The data are presented without analysis.

  6. Performance Characteristics of an Isothermal Freeze Valve

    SciTech Connect

    Hailey, A.E.

    2001-08-22

    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  7. The Aerodynamic Performance of an Over-the-Rotor Liner With Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F.; Hughes, Christopher E.; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1 percent which is within the repeatability of this experiment.

  8. The Aerodynamic Performance of an Over-The-Rotor Liner with Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Rick; Hughes, Christopher; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1% which is within the repeatability of this experiment.

  9. Validation of a computer code for analysis of subsonic aerodynamic performance of wings with flaps in combination with a canard or horizontal tail and an application to optimization

    NASA Technical Reports Server (NTRS)

    Carlson, Harry W.; Darden, Christine M.; Mann, Michael J.

    1990-01-01

    Extensive correlations of computer code results with experimental data are employed to illustrate the use of a linearized theory, attached flow method for the estimation and optimization of the longitudinal aerodynamic performance of wing-canard and wing-horizontal tail configurations which may employ simple hinged flap systems. Use of an attached flow method is based on the premise that high levels of aerodynamic efficiency require a flow that is as nearly attached as circumstances permit. The results indicate that linearized theory, attached flow, computer code methods (modified to include estimated attainable leading-edge thrust and an approximate representation of vortex forces) provide a rational basis for the estimation and optimization of aerodynamic performance at subsonic speeds below the drag rise Mach number. Generally, good prediction of aerodynamic performance, as measured by the suction parameter, can be expected for near optimum combinations of canard or horizontal tail incidence and leading- and trailing-edge flap deflections at a given lift coefficient (conditions which tend to produce a predominantly attached flow).

  10. Effect of empennage location on twin-engine afterbody-nozzle aerodynamic characteristics at Mach Numbers from 0.6 to 1.2. [wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Leavitt, L. D.

    1983-01-01

    The Langley 16-foot transonic tunnel was used to determine the effects of several empennage and afterbody parameters on the aft-end aerodynamic characteristics of a twin-engine fighter-type configuration. Model variables were as follows: horizontal tail axial location and incidence, vertical tail axial location and configuration (twin- versus single-tail arrangements), tail booms, and nozzle power setting. Tests were conducted over a Mach number range from 0.6 to 1.2 and over an angle-of-attack from -2 deg to 10 deg. Jet total-pressure ratio was varied from jet off to approximately 10.0.

  11. Investigation of the Aerodynamic Characteristics of a Model Wing-Propeller Combination and of the Wing and Propeller Separately at Angles of Attack up to 90 Degrees

    NASA Technical Reports Server (NTRS)

    Kuhn, Richard E; Draper, John W

    1956-01-01

    This report presents the results of an investigation conducted in the Langley 300 mph 7- by 10-foot wind tunnel for the purpose of determining the aerodynamic characteristics of a model wing-propeller combination, and of the wing and propeller separately at angles of attack up to 90 degrees. The tests covered thrust coefficients corresponding to free-stream velocities from zero forward speed to the normal range of cruising speeds. The results indicate that increasing the thrust coefficient increases the angle of attack for maximum lift and greatly diminishes the usual reduction in lift above the angle of attack for maximum lift.

  12. Low-speed aerodynamic characteristics of a 42 deg swept high-wing model having a double-slotted flap system and a supercritical airfoil

    NASA Technical Reports Server (NTRS)

    Fournier, P. G.; Goodson, K. W.

    1974-01-01

    A low-speed investigation was conducted over an angle-of-attack range from about -4 deg to 20 deg in the Langley V/STOL tunnel to determine the effects of a double-slotted flap, high-lift system on the aerodynamic characteristics of a 42 deg swept high-wing model having a supercritical airfoil. The wing had an aspect ratio of 6.78 and a taper ratio of 0.36; the double-slotted flap consisted of a 35-percent-chord flap with a 15-percent-chord vane. The model was tested with a 15-percent-chord leading-edge slat.

  13. Low subsonic aerodynamic characteristics of five irregular planform wings with systematically varying wing fillet geometry tested in the NASA/Ames 12 foot pressure tunnel (LA65)

    NASA Technical Reports Server (NTRS)

    Ball, J. W.; Watson, D. B.

    1976-01-01

    An experimental and analytical aerodynamic program to develop predesign guides for irregular planform wings (also referred to as cranked leading edge or double delta wings is reported; the benefits are linearization of subsonic lift curve slope to high angles of attack and avoidance of subsonic pitch instabilities at high lift by proper tailoring of the planform-fillet-wing combination while providing the desired hypersonic trim angle and stability. Because subsonic and hypersonic conditions were the two prime areas of concern in the initial application of this program to optimize shuttle orbiter landing and entry characteristics, the study was designated the Subsonic/Hypersonic Irregular Planforms Study (SHIPS).

  14. A computer program for calculating symmetrical aerodynamic characteristics and lateral-directional stability derivatives of wing-body combinations with blowing jets

    NASA Technical Reports Server (NTRS)

    Lan, C. E.; Mehrotra, S. C.; Fox, C. H., Jr.

    1978-01-01

    The necessary information for using a computer program to calculate the aerodynamic characteristics under symmetrical flight conditions and the lateral-directional stability derivatives of wing-body combinations with upper-surface-blowing (USB) or over-wing-blowing (OWB) jets are described. The following new features were added to the program: (1) a fuselage of arbitrary body of revolution has been included. The effect of wing-body interference can now be investigated, and (2) all nine lateral-directional stability derivatives can be calculated. The program is written in FORTRAN language and runs on CDC Cyber 175 and Honeywell 66/60 computers.

  15. Effects of twin-vertical-tail parameters on twin-engine afterbody/nozzle aerodynamic characteristics. [Langley 16-ft transonic tunnel tests

    NASA Technical Reports Server (NTRS)

    Leavitt, L. D.; Bare, E. A.

    1983-01-01

    The Langley 16-foot transonic tunnel was used to determine the effects of several empennage and afterbody parameters on twin-engine aft-end aerodynamic characteristics. Model variables included twin-vertical-tail cant angle, toe angle, airfoil camber, and root-chord length and afterbody/engine interfairing shape. Tests were conducted over a Mach number range from 0.6 to 1.2 and over an angle-of-attack range from 2 deg to 10 deg. Nozzle pressure ratio was varied from 1.0 (jet off) to approximately 10.0.

  16. Aerodynamic characteristics of a six-jet V/STOL configuration with four swing-out lift jets in the transition speed range

    NASA Technical Reports Server (NTRS)

    Carter, A. W.

    1970-01-01

    A wind-tunnel investigation has been made of the longitudinal aerodynamic characteristics and jet-interference effects of a model of a jet V/STOL variable-sweep fighter airplane that employs four direct-lift engines which swing out from the fuselage and two lift-cruise engines located in the rear part of the fuselage. Data were obtained with two wing areas for various forward speeds and power conditions in the transition speed range. The data are presented without analysis or discussion.

  17. Aerodynamic characteristics of a vane flow angularity sensor system capable of measuring flight path accelerations for the Mach number range from 0.40 to 2.54

    NASA Technical Reports Server (NTRS)

    Sakamoto, G. M.

    1976-01-01

    The aerodynamic characteristics of the angle of attack vane and the angle of sideslip vane are summarized. The test conditions ranged in free stream Mach number from 0.40 to 2.54, in angle of attack from -2 deg to 22 deg, in angle of sideslip from -2 deg to 12 deg, and in Reynolds number from 590,000 per meter to 1.8 million per meter. The results of the wind tunnel investigation are compared with results obtained with similar vane configurations. Comparisons with a NACA vane configuration are also made. In addition, wind tunnel-derived upwash for the test installation is compared with analytical predictions.

  18. Effect of nacelles on aerodynamic characteristics of an executive-jet model with simulated, partial-chord, laminar-flow-control wing glove

    NASA Technical Reports Server (NTRS)

    Campbell, R. L.

    1982-01-01

    Tests were conducted in the Langley High-Speed 7- by 10-Foot Tunnel using a 1/10-scale model of an executive jet to examine the effects of the nacelles on the wing pressures and model longitudinal aerodynamic characteristics. For the present investigation, each wing panel was modified with a simulated, partial-chord, laminar-flow-control glove. Horizontal-tail effects were also briefly examined. The tests covered a range of Mach numbers from 0.40 to 0.82 and lift coefficients from 0.20 to 0.55. Oil-flow photographs of the wing at selected conditions are included.

  19. A Collaborative Analysis Tool for Integrated Hypersonic Aerodynamics, Thermal Protection Systems, and RBCC Engine Performance for Single Stage to Orbit Vehicles

    NASA Technical Reports Server (NTRS)

    Stanley, Thomas Troy; Alexander, Reginald; Landrum, Brian

    2000-01-01

    engine model. HYFIM performs the aerodynamic analysis of forebodies and inlet characteristics of RBCC powered SSTO launch vehicles. HYFIM is applicable to the analysis of the ramjet/scramjet engine operations modes (Mach 3-12), and provides estimates of parameters such as air capture area, shock-on-lip Mach number, design Mach number, compression ratio, etc., based on a basic geometry routine for modeling axisymmetric cones, 2-D wedge geometries. HYFIM also estimates the variation of shock layer properties normal to the forebody surface. The thermal protection system (TPS) is directly linked to determination of the vehicle moldline and the shaping of the trajectory. Thermal protection systems to maintain the structural integrity of the vehicle must be able to mitigate the heat transfer to the structure and be lightweight. Herein lies the interdependency, in that as the vehicle's speed increases, the TPS requirements are increased. And as TPS masses increase the effect on the propulsion system and all other systems is compounded. The need to analyze vehicle forebody and engine inlet is critical to be able to design the RBCC vehicle. To adequately determine insulation masses for an RBCC vehicle, the hypersonic aerodynamic environment and aeroheating loads must be calculated and the TPS thicknesses must be calculated for the entire vehicle. To accomplish this an ascent or reentry trajectory is obtained using the computer code Program to Optimize Simulated Trajectories (POST). The trajectory is then used to calculate the convective heat rates on several locations on the vehicles using the Miniature Version of the JA70 Aerodynamic Heating Computer Program (MINIVER). Once the heat rates are defined for each body point on the vehicle, then insulation thicknesses that are required to maintain the vehicle within structural limits are calculated using Systems Improved Numerical Differencing Analyzer (SINDA) models. If the TPS masses are too heavy for the performance of the vehicle

  20. Characterization of Aerodynamic Performance of Boundary-Layer-Ingesting Inlet Under Crosswind

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Lee, Byung Joon

    2012-01-01

    NASA has been studying future transport concepts, envisioned to be technically realizable in the timeframe of 2020-2030, to meet environmental and performance goals. One concept receiving considerable interest involves a propulsion system embedded into a hybrid wing-body aircraft. While offering significant advantages in fuel savings and noise reduction by this concept, there are several technical challenges that are not encountered in the current fleet and must be overcome so as to deliver target performance and operability. One of these challenges is associated with an inlet system that ingests a significantly thick boundary layer, developing along the wing-body surface, into a serpentine diffuser before the flow meeting fan blades. The flow is subject to considerable total pressure loss and distorted at the fan face, much more significantly than in the inlet system of conventional aircraft. In our previous studies [1, 2], we have shown that through innovative design changes on the airframe surface, it is possible to simultaneously increase total pressure recovery and decrease distortion in the flow, without resorting to conventional penalty-ridden flow control concepts, such as vortex generator or boundary layer bleeding/suction. In the current study, we are interested in understanding the following issues: how the embedded propulsion system performs under a crosswind condition by studying in detail the flow characteristics of two inlets, the baseline and another optimized previously under the cruise condition. With the insight, it is hoped that it can help in the follow-on study by devising effective strategies to minimize flow distortion arising from the integration of an embedded-engine system into an airframe to the level acceptable to the operation and fuel consumption before 2030. To achieve these demanding goals, non-conventional concepts are called for; but technology gap is too big that it requires evolutionary approach by focusing various concepts and

  1. Post-Flight Aerodynamic and Aerothermal Model Validation of a Supersonic Inflatable Aerodynamic Decelerator

    NASA Technical Reports Server (NTRS)

    Tang, Chun; Muppidi, Suman; Bose, Deepak; Van Norman, John W.; Tanimoto, Rebekah; Clark, Ian

    2015-01-01

    NASA's Low Density Supersonic Decelerator Program is developing new technologies that will enable the landing of heavier payloads in low density environments, such as Mars. A recent flight experiment conducted high above the Hawaiian Islands has demonstrated the performance of several decelerator technologies. In particular, the deployment of the Robotic class Supersonic Inflatable Aerodynamic Decelerator (SIAD-R) was highly successful, and valuable data were collected during the test flight. This paper outlines the Computational Fluid Dynamics (CFD) analysis used to estimate the aerodynamic and aerothermal characteristics of the SIAD-R. Pre-flight and post-flight predictions are compared with the flight data, and a very good agreement in aerodynamic force and moment coefficients is observed between the CFD solutions and the reconstructed flight data.

  2. Vortex wake, downwash distribution, aerodynamic performance and wingbeat kinematics in slow-flying pied flycatchers

    PubMed Central

    Muijres, Florian T.; Bowlin, Melissa S.; Johansson, L. Christoffer; Hedenström, Anders

    2012-01-01

    Many small passerines regularly fly slowly when catching prey, flying in cluttered environments or landing on a perch or nest. While flying slowly, passerines generate most of the flight forces during the downstroke, and have a ‘feathered upstroke’ during which they make their wing inactive by retracting it close to the body and by spreading the primary wing feathers. How this flight mode relates aerodynamically to the cruising flight and so-called ‘normal hovering’ as used in hummingbirds is not yet known. Here, we present time-resolved fluid dynamics data in combination with wingbeat kinematics data for three pied flycatchers flying across a range of speeds from near hovering to their calculated minimum power speed. Flycatchers are adapted to low speed flight, which they habitually use when catching insects on the wing. From the wake dynamics data, we constructed average wingbeat wakes and determined the time-resolved flight forces, the time-resolved downwash distributions and the resulting lift-to-drag ratios, span efficiencies and flap efficiencies. During the downstroke, slow-flying flycatchers generate a single-vortex loop wake, which is much more similar to that generated by birds at cruising flight speeds than it is to the double loop vortex wake in hovering hummingbirds. This wake structure results in a relatively high downwash behind the body, which can be explained by the relatively active tail in flycatchers. As a result of this, slow-flying flycatchers have a span efficiency which is similar to that of the birds in cruising flight and which can be assumed to be higher than in hovering hummingbirds. During the upstroke, the wings of slowly flying flycatchers generated no significant forces, but the body–tail configuration added 23 per cent to weight support. This is strikingly similar to the 25 per cent weight support generated by the wing upstroke in hovering hummingbirds. Thus, for slow-flying passerines, the upstroke cannot be regarded as

  3. Vortex wake, downwash distribution, aerodynamic performance and wingbeat kinematics in slow-flying pied flycatchers.

    PubMed

    Muijres, Florian T; Bowlin, Melissa S; Johansson, L Christoffer; Hedenström, Anders

    2012-02-07

    Many small passerines regularly fly slowly when catching prey, flying in cluttered environments or landing on a perch or nest. While flying slowly, passerines generate most of the flight forces during the downstroke, and have a 'feathered upstroke' during which they make their wing inactive by retracting it close to the body and by spreading the primary wing feathers. How this flight mode relates aerodynamically to the cruising flight and so-called 'normal hovering' as used in hummingbirds is not yet known. Here, we present time-resolved fluid dynamics data in combination with wingbeat kinematics data for three pied flycatchers flying across a range of speeds from near hovering to their calculated minimum power speed. Flycatchers are adapted to low speed flight, which they habitually use when catching insects on the wing. From the wake dynamics data, we constructed average wingbeat wakes and determined the time-resolved flight forces, the time-resolved downwash distributions and the resulting lift-to-drag ratios, span efficiencies and flap efficiencies. During the downstroke, slow-flying flycatchers generate a single-vortex loop wake, which is much more similar to that generated by birds at cruising flight speeds than it is to the double loop vortex wake in hovering hummingbirds. This wake structure results in a relatively high downwash behind the body, which can be explained by the relatively active tail in flycatchers. As a result of this, slow-flying flycatchers have a span efficiency which is similar to that of the birds in cruising flight and which can be assumed to be higher than in hovering hummingbirds. During the upstroke, the wings of slowly flying flycatchers generated no significant forces, but the body-tail configuration added 23 per cent to weight support. This is strikingly similar to the 25 per cent weight support generated by the wing upstroke in hovering hummingbirds. Thus, for slow-flying passerines, the upstroke cannot be regarded as inactive

  4. A Collaborative Analysis Tool for Integrated Hypersonic Aerodynamics, Thermal Protection Systems, and RBCC Engine Performance for Single Stage to Orbit Vehicles

    NASA Technical Reports Server (NTRS)

    Stanley, Thomas Troy; Alexander, Reginald; Landrum, Brian

    2000-01-01

    engine model. HYFIM performs the aerodynamic analysis of forebodies and inlet characteristics of RBCC powered SSTO launch vehicles. HYFIM is applicable to the analysis of the ramjet/scramjet engine operations modes (Mach 3-12), and provides estimates of parameters such as air capture area, shock-on-lip Mach number, design Mach number, compression ratio, etc., based on a basic geometry routine for modeling axisymmetric cones, 2-D wedge geometries. HYFIM also estimates the variation of shock layer properties normal to the forebody surface. The thermal protection system (TPS) is directly linked to determination of the vehicle moldline and the shaping of the trajectory. Thermal protection systems to maintain the structural integrity of the vehicle must be able to mitigate the heat transfer to the structure and be lightweight. Herein lies the interdependency, in that as the vehicle's speed increases, the TPS requirements are increased. And as TPS masses increase the effect on the propulsion system and all other systems is compounded. The need to analyze vehicle forebody and engine inlet is critical to be able to design the RBCC vehicle. To adequately determine insulation masses for an RBCC vehicle, the hypersonic aerodynamic environment and aeroheating loads must be calculated and the TPS thicknesses must be calculated for the entire vehicle. To accomplish this an ascent or reentry trajectory is obtained using the computer code Program to Optimize Simulated Trajectories (POST). The trajectory is then used to calculate the convective heat rates on several locations on the vehicles using the Miniature Version of the JA70 Aerodynamic Heating Computer Program (MINIVER). Once the heat rates are defined for each body point on the vehicle, then insulation thicknesses that are required to maintain the vehicle within structural limits are calculated using Systems Improved Numerical Differencing Analyzer (SINDA) models. If the TPS masses are too heavy for the performance of the vehicle

  5. Computational fluid dynamics analysis of cyclist aerodynamics: performance of different turbulence-modelling and boundary-layer modelling approaches.

    PubMed

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

    2010-08-26

    This study aims at assessing the accuracy of computational fluid dynamics (CFD) for applications in sports aerodynamics, for example for drag predictions of swimmers, cyclists or skiers, by evaluating the applied numerical modelling techniques by means of detailed validation experiments. In this study, a wind-tunnel experiment on a scale model of a cyclist (scale 1:2) is presented. Apart from three-component forces and moments, also high-resolution surface pressure measurements on the scale model's surface, i.e. at 115 locations, are performed to provide detailed information on the flow field. These data are used to compare the performance of different turbulence-modelling techniques, such as steady Reynolds-averaged Navier-Stokes (RANS), with several k-epsilon and k-omega turbulence models, and unsteady large-eddy simulation (LES), and also boundary-layer modelling techniques, namely wall functions and low-Reynolds number modelling (LRNM). The commercial CFD code Fluent 6.3 is used for the simulations. The RANS shear-stress transport (SST) k-omega model shows the best overall performance, followed by the more computationally expensive LES. Furthermore, LRNM is clearly preferred over wall functions to model the boundary layer. This study showed that there are more accurate alternatives for evaluating flow around bluff bodies with CFD than the standard k-epsilon model combined with wall functions, which is often used in CFD studies in sports.

  6. Aerodynamic performance of conventional and advanced design labyrinth seals with solid-smooth abradable, and honeycomb lands. [gas turbine engines

    NASA Technical Reports Server (NTRS)

    Stocker, H. L.; Cox, D. M.; Holle, G. F.

    1977-01-01

    Labyrinth air seal static and dynamic performance was evaluated using solid, abradable, and honeycomb lands with standard and advanced seal designs. The effects on leakage of land surface roughness, abradable land porosity, rub grooves in abradable lands, and honeycomb land cell size and depth were studied using a standard labyrinth seal. The effects of rotation on the optimum seal knife pitch were also investigated. Selected geometric and aerodynamic parameters for an advanced seal design were evaluated to derive an optimized performance configuration. The rotational energy requirements were also measured to determine the inherent friction and pumping energy absorbed by the various seal knife and land configurations tested in order to properly assess the net seal system performance level. Results indicate that: (1) seal leakage can be significantly affected with honeycomb or abradable lands; (2) rotational energy absorption does not vary significantly with the use of a solid-smooth, an abradable, or a honeycomb land; and (3) optimization of an advanced lab seal design produced a configuration that had leakage 25% below a conventional stepped seal.

  7. A ballistic investigation of the aerodynamic characteristics of a blunt vehicle at hypersonic speeds in carbon dioxide and air

    NASA Technical Reports Server (NTRS)

    Packard, James D.; Griffith, Wayland C.; Yates, Leslie A.; Strawa, Anthony W.

    1992-01-01

    Missions to Mars require the successful development of aerobraking technology, and therefore a blunt cone representative of aerobrake shapes is investigated. Ballistic tests of the Pioneer Venus configuration are conducted in carbon dioxide and air at Mach numbers from 7 to 20 and Reynolds numbers from 0.1 x 10 exp 5 to 4 x 10 exp 6. Experimental results show that for defined conditions aerodynamic research can be conducted in air rather than carbon dioxide, providing savings in time and money. In addition, the results offer a prediction of flight aerodynamics during entry into the Martian atmosphere. Also discussed is a comparison of results from two data-reduction techniques showing that a five-degree-of-freedom routine employing weighted least-squares with differential corrections analyzes ballistic data more accurately.

  8. Some effects of wing and body geometry on the aerodynamic characteristics of configurations designed for high supersonic Mach numbers

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.; Tice, David C.; Braswell, Dorothy O.

    1992-01-01

    Experimental and theoretical results are presented for a family of aerodynamic configurations for flight Mach numbers as high as Mach 8. All of these generic configurations involved 70-deg sweep delta planform wings of three different areas and three fuselage shapes with circular-to-elliptical cross sections. It is noted that fuselage ellipticity enhances lift-curve slope and maximum L/D, while decreasing static longitudinal stability (especially with smaller wing areas).

  9. Low-speed aerodynamic characteristics of a transport configuration having a 42 deg swept supercritical airfoil wing and three tail height positions

    NASA Technical Reports Server (NTRS)

    Fournier, P. G.; Sleeman, W. C., Jr.

    1974-01-01

    A low speed investigation was conducted in the Langley V/STOL tunnel to define the static stability characteristics of an advanced high subsonic speed transport aircraft model in the cruise configuration (no high lift system). The wing of the model had 42 deg sweep of the quarter chord line, an aspect ratio of 6.78, and supercritical airfoil sections. Three different horizontal tail configurations (high, mid, and low) were investigated on the complete model and for the model with the wing removed in order to assess effects of the wing flow field on the tail contributions to both longitudinal and lateral stability characteristics. All the model configurations investigated were tested over an angle of attack range from approximately -5 to 23 deg. Some model configurations were also tested over an angle of attack range from about 11 to 38 deg in order to explore the aerodynamic characteristics in the deep stall region.

  10. Validation of a pair of computer codes for estimation and optimization of subsonic aerodynamic performance of simple hinged-flap systems for thin swept wings

    NASA Technical Reports Server (NTRS)

    Carlson, Harry W.; Darden, Christine M.

    1988-01-01

    Extensive correlations of computer code results with experimental data are employed to illustrate the use of linearized theory attached flow methods for the estimation and optimization of the aerodynamic performance of simple hinged flap systems. Use of attached flow methods is based on the premise that high levels of aerodynamic efficiency require a flow that is as nearly attached as circumstances permit. A variety of swept wing configurations are considered ranging from fighters to supersonic transports, all with leading- and trailing-edge flaps for enhancement of subsonic aerodynamic efficiency. The results indicate that linearized theory attached flow computer code methods provide a rational basis for the estimation and optimization of flap system aerodynamic performance at subsonic speeds. The analysis also indicates that vortex flap design is not an opposing approach but is closely related to attached flow design concepts. The successful vortex flap design actually suppresses the formation of detached vortices to produce a small vortex which is restricted almost entirely to the leading edge flap itself.

  11. Performance Characteristics of a Preformed Elliptical Parachute

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Performance Characteristics of a Preformed Elliptical Parachute at Altitudes between 200,000 and 100,000 Thousand Feet Obtained by In-Flight Photography. The performance characteristics of a pre-formed elliptical parachute at altitudes between 200,000 and 100,000 feet were obtained by means of in-flight photography. The tests demonstrate that this type of parachute will open at altitudes of about 200,000 feet if conditions such as twisting of the suspension lines or draping of the suspension lines over the canopy do not occur. Drag-coefficient values between 0.6 and 0.8 were found to be reasonable for this type of parachute system in the altitude range between 200,000 and 100,000 feet. [Entire movie available on DVD from CASI as Doc ID 20070030980. Contact help@sti.nasa.gov

  12. Improvement of the cruise performances of a wing by means of aerodynamic optimization. Validation with a Far-Field method

    NASA Astrophysics Data System (ADS)

    Jiménez-Varona, J.; Ponsin Roca, J.

    2015-06-01

    Under a contract with AIRBUS MILITARY (AI-M), an exercise to analyze the potential of optimization techniques to improve the wing performances at cruise conditions has been carried out by using an in-house design code. The original wing was provided by AI-M and several constraints were posed for the redesign. To maximize the aerodynamic efficiency at cruise, optimizations were performed using the design techniques developed internally at INTA under a research program (Programa de Termofluidodinámica). The code is a gradient-based optimizaa tion code, which uses classical finite differences approach for gradient computations. Several techniques for search direction computation are implemented for unconstrained and constrained problems. Techniques for geometry modifications are based on different approaches which include perturbation functions for the thickness and/or mean line distributions and others by Bézier curves fitting of certain degree. It is very e important to afford a real design which involves several constraints that reduce significantly the feasible design space. And the assessment of the code is needed in order to check the capabilities and the possible drawbacks. Lessons learnt will help in the development of future enhancements. In addition, the validation of the results was done using also the well-known TAU flow solver and a far-field drag method in order to determine accurately the improvement in terms of drag counts.

  13. Acoustic and aerodynamic performance of a variable-pitch 1.83-meter-(6-ft) diameter 1.20-pressure-ratio fan stage (QF-9)

    NASA Technical Reports Server (NTRS)

    Glaser, F. W.; Woodward, R. P.; Lucas, J. G.

    1977-01-01

    Far field noise data and related aerodynamic performance are presented for a variable pitch fan stage having characteristics suitable for low noise, STOL engine application. However, no acoustic suppression material was used in the flow passages. The fan was externally driven by an electric motor. Tests were made at several forward thrust rotor blade pitch angles and one for reverse thrust. Fan speed was varied from 60 to 120 percent of takeoff (design) speed, and exhaust nozzles having areas 92 to 105 percent of design were tested. The fan noise level was at a minimum at the design rotor blade pitch angles of 64 deg for takeoff thrust and at 57 deg for approach (50 percent takeoff thrust). Perceived noise along a 152.4-m sideline reached 100.1 PNdb for the takeoff (design) configuration for a stage pressure ratio of 1.17 and thrust of 57,600 N. For reverse thrust the PNL values were 4 to 5 PNdb above the takeoff values at comparable fan speeds.

  14. Wind-tunnel investigation of aerodynamic characteristics and wing pressure distributions of an airplane with variable-sweep wings modified for laminar flow

    NASA Technical Reports Server (NTRS)

    Hallissy, James B.; Phillips, Pamela S.

    1989-01-01

    A wind tunnel test was conducted to evaluate the aerodynamic characteristics and wing pressure distributions of a variable wing sweep aircraft having wing panels that are modified to promote laminar flow. The modified wing section shapes were incorporated over most of the exposed outer wing panel span and were obtained by extending the leading edge and adding thickness to the existing wing upper surface forward of 60 percent chord. Two different wing configurations, one each for Mach numbers 0.7 and 0.8, were tested on the model simultaneously, with one wing configuration on the left side and the other on the right. The tests were conducted at Mach numbers 0.20 to 0.90 for wing sweep angles of 20, 25, 30, and 35 degrees. Longitudinal, lateral and directional aerodynamic characteristics of the modified and baseline configurations, and selected pressure distributions for the modified configurations, are presented in graphical form without analysis. A tabulation of the pressure data for the modified configuration is available as microfiche.

  15. Effect of rotor wake on aerodynamic characteristics of a 1/6 scale model of the rotor systems research aircraft. [in the Langley V/STOL tunnel

    NASA Technical Reports Server (NTRS)

    Mineck, R. E.

    1977-01-01

    Tests were conducted in the Langley V/STOL tunnel to determine the effect of the main-rotor wake on the aerodynamic characteristics of the rotor systems research aircraft. A 1/6-scale model with a 4-blade articulated rotor was used to determine the effect of the rotor wake for the compound configuration. Data were obtained over a range of angles of attack, angles of sideslip, auxiliary engine thrusts, rotor collective pitch angles, and rotor tip-path plane angles for several main-rotor advance ratios. Separate results are presented for the forces and moments on the airframe, the wing, and the tail. An analysis of the test data indicates significant changes in the aerodynamic characteristics. The rotor wake increases the longitudinal static stability, the effective dihedral, and the lateral static stability of the airframe. The rotor induces a downwash on the wing. This downwash decreases the wing lift and increases the drag. The asymmetrical rotor wake induces a differential lift across the wing and a subsequent rolling moment. These rotor induced effects on the wing become smaller with increasing forward speed.

  16. Some Effects of Nose Bluntness and Fineness Ratio on the Static Longitudinal Aerodynamic Characteristics of Bodies of Revolution at Subsonic Speeds

    NASA Technical Reports Server (NTRS)

    Hayes, William C., Jr.; Henderson, William P.

    1961-01-01

    . The effects of a systematic variation of nose shape and fineness ratio on the longitudinal aerodynamic characteristics of bodies of revolution have been qualitatively determined at subsonic speeds. Six nose shapes were investigated, representing five corner radii which varied from 0 to 50 percent of the body diameter and three face radii which varied from 50 percent of the model diameter to infinity. The complete models had fineness ratios of 0.50 to 2.00. In addition, effects of boattailing the afterbody and removing or varying the transitions trips which had been attached to initiate a turbulent boundary layer were noted. Results are presented for an angle-of-attack range from -4 deg to 24 deg for Mach numbers from 0.25 to 0.80, and indicate that small variations of the model nose can produce large variations in the static longitudinal aerodynamic characteristics of the body. These variations may in turn be moderated by an increase in the model fineness ratio .

  17. Aerodynamic Loading Characteristics Including Effects of Aeroelasticity of a Thin-Trapezoidal-Wing-Body Combination at Mach Number of 1.43

    NASA Technical Reports Server (NTRS)

    Kelly, Thomas C.

    1959-01-01

    Results have been obtained in the Langley 8-foot transonic pressure tunnel at a Mach number of 1.43 and at angles of attack from 0 deg to about 24 deg which indicate the static-aerodynamic-loads characteristics for a 2-percent-thick trapezoidal wing in combination with a body. Included are the effects of changing Reynolds number and of fixing boundary-layer transition. The results show that aerodynamic loading characteristics at a Mach number of 1.43 are similar to those reported in NACA RM L56Jl2a for the same configuration at a Mach number of 1.115. Reducing the Reynolds number resulted in reductions in the deflection of the wing and caused a slight increase in the relative loading over the outboard wing sections since the deflections were in a direction to unload the tip sections. Little or no effects were seen to result from fixing boundary-layer transition at a tunnel stagnation pressure of 1,950 pounds per square foot.

  18. Initial Investigation on the Aerodynamic Performance of Flapping Wings for Nano Air Vehicles

    DTIC Science & Technology

    2008-02-01

    though there has been considerable analysis of bird and insect flight mechanisms, no machine at the size level of a hummingbird has been demonstrated...characteristics: - 4 wing “Double- Hummingbird ” X-wing configuration developed for Mentor - Capable of hover and fast translation flight - Single degree of...Biological creatures have good duration – Ruby-throated hummingbird crosses the Gulf of Mexico (30 hr flight) Fuel-burners are still the best but

  19. Dual nozzle aerodynamic and cooling analysis study

    NASA Technical Reports Server (NTRS)

    Meagher, G. M.

    1981-01-01

    Analytical models to predict performance and operating characteristics of dual nozzle concepts were developed and improved. Aerodynamic models are available to define flow characteristics and bleed requirements for both the dual throat and dual expander concepts. Advanced analytical techniques were utilized to provide quantitative estimates of the bleed flow, boundary layer, and shock effects within dual nozzle engines. Thermal analyses were performed to define cooling requirements for baseline configurations, and special studies of unique dual nozzle cooling problems defined feasible means of achieving adequate cooling.

  20. Aeroelastic characteristics of a rapid prototype multi-material wind tunnel model of a mechanically deployable aerodynamic decelerator

    NASA Astrophysics Data System (ADS)

    Raskin, Boris

    Scaled wind tunnel models are necessary for the development of aircraft and spacecraft to simulate aerodynamic behavior. This allows for testing multiple iterations of a design before more expensive full-scale aircraft and spacecraft are built. However, the cost of building wind tunnel models can still be high because they normally require costly subtractive manufacturing processes, such as machining, which can be time consuming and laborious due to the complex surfaces of aerodynamic models. Rapid prototyping, commonly known as 3D printing, can be utilized to save on wind tunnel model manufacturing costs. A rapid prototype multi-material wind tunnel model was manufactured for this thesis to investigate the possibility of using PolyJet 3D printing to create a model that exhibits aeroelastic behavior. The model is of NASA's Adaptable Deployable entry and Placement (ADEPT) aerodynamic decelerator, used to decelerate a spacecraft during reentry into a planet's atmosphere. It is a 60° cone with a spherically blunted nose that consists of a 12 flexible panels supported by a rigid structure of nose, ribs, and rim. The novel rapid prototype multi-material model was instrumented and tested in two flow conditions. Quantitative comparisons were made of the average forces and dynamic forces on the model, demonstrating that the model matched expected behavior for average drag, but not Strouhal number, indicating that there was no aeroelastic behavior in this particular case. It was also noted that the dynamic properties (e.g., resonant frequency) associated with the mounting scheme are very important and may dominate the measured dynamic response.