First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop

NASA Technical Reports Server (NTRS)

Wood, Richard M. (Editor)

1999-01-01

This publication is a compilation of documents presented at the First NASA/Industry High Speed Research Configuration Aerodynamics Workshop held on February 27-29, 1996 at NASA Langley Research Center. The purpose of the workshop was to bring together the broad spectrum of aerodynamicists, engineers, and scientists working within the Configuration Aerodynamics element of the HSR Program to collectively evaluate the technology status and to define the needs within Computational Fluid Dynamics (CFD) Analysis Methodology, Aerodynamic Shape Design, Propulsion/Airframe Integration (PAI), Aerodynamic Performance, and Stability and Control (S&C) to support the development of an economically viable High Speed Civil Transport (HSCT) aircraft. To meet these objectives, papers were presented by representative from NASA Langley, Ames, and Lewis Research Centers; Boeing, McDonnell Douglas, Northrop-Grumman, Lockheed-Martin, Vigyan, Analytical Services, Dynacs, and RIACS.

Advanced aerodynamics and active controls. Selected NASA research

NASA Technical Reports Server (NTRS)

1981-01-01

Aerodynamic and active control concepts for application to commercial transport aircraft are discussed. Selected topics include in flight direct strike lightning research, triply redundant digital fly by wire control systems, tail configurations, winglets, and the drones for aerodynamic and structural testing (DAST) program.

Survey of lift-fan aerodynamic technology

NASA Technical Reports Server (NTRS)

Hickey, David H.; Kirk, Jerry V.

1993-01-01

Representatives of NASA Ames Research Center asked that a summary of technology appropriate for lift-fan powered short takeoff/vertical landing (STOVL) aircraft be prepared so that new programs could more easily benefit from past research efforts. This paper represents one of six prepared for that purpose. The authors have conducted or supervised the conduct of research on lift-fan powered STOVL designs and some of their important components for decades. This paper will first address aerodynamic modeling requirements for experimental programs to assure realistic, trustworthy results. It will next summarize the results or efforts to develop satisfactory specialized STOVL components such as inlets and flow deflectors. It will also discuss problems with operation near the ground, aerodynamics while under lift-fan power, and aerodynamic prediction techniques. Finally, results of studies to reduce lift-fan noise will be presented. The paper will emphasize results from large scale experiments, where available, for reasons that will be brought out in the discussion. Some work with lift-engine powered STOVL aircraft is also applicable to lift-fan technology and will be presented herein. Small-scale data will be used where necessary to fill gaps.

Web-Based Integrated Research Environment for Aerodynamic Analyses and Design

NASA Astrophysics Data System (ADS)

Ahn, Jae Wan; Kim, Jin-Ho; Kim, Chongam; Cho, Jung-Hyun; Hur, Cinyoung; Kim, Yoonhee; Kang, Sang-Hyun; Kim, Byungsoo; Moon, Jong Bae; Cho, Kum Won

e-AIRS[1,2], an abbreviation of ‘e-Science Aerospace Integrated Research System,' is a virtual organization designed to support aerodynamic flow analyses in aerospace engineering using the e-Science environment. As the first step toward a virtual aerospace engineering organization, e-AIRS intends to give a full support of aerodynamic research process. Currently, e-AIRS can handle both the computational and experimental aerodynamic research on the e-Science infrastructure. In detail, users can conduct a full CFD (Computational Fluid Dynamics) research process, request wind tunnel experiment, perform comparative analysis between computational prediction and experimental measurement, and finally, collaborate with other researchers using the web portal. The present paper describes those services and the internal architecture of the e-AIRS system.

First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop. Pt. 2

NASA Technical Reports Server (NTRS)

Wood, Richard M. (Editor)

1999-01-01

This publication is a compilation of documents presented at the First NASA Industry High Speed Research Configuration Aerodynamics Workshop held on February 27-29, 1996 at NASA Langley Research Center. The purpose of the workshop was to bring together the broad spectrum of aerodynamicists, engineers, and scientists working within the Configuration Aerodynamics element of the HSR Program to collectively evaluate the technology status and to define the needs within Computational Fluid Dynamics (CFD) Analysis Methodology, Aerodynamic Shape Design, Propulsion/Airframe Integration (PAI), Aerodynamic Performance, and Stability and Control (S&C) to support the development of an economically viable High Speed Civil Transport (HSCT) aircraft. To meet these objectives, papers were presented by representatives from NASA Langley, Ames, and Lewis Research Centers; Boeing, McDonnell Douglas, Northrop-Grumman, Lockheed-Martin, Vigyan, Analytical Services, Dynacs, and RIACS.

First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop. Part 1

NASA Technical Reports Server (NTRS)

Wood, Richard M. (Editor)

1999-01-01

This publication is a compilation of documents presented at the First NASA/Industry High Speed Research Configuration Aerodynamics Workshop held on February 27-29, 1996 at NASA Langley Research Center. The purpose of the workshop was to bring together the broad spectrum of aerodynamicists, engineers, and scientists working within the Configuration Aerodynamics element of the HSR Program to collectively evaluate the technology status and to define the needs within Computational Fluid Dynamics (CFD) Analysis Methodology, Aerodynamic Shape Design, Propulsion/Airframe Integration (PAI), Aerodynamic Performance, and Stability and Control (S&C) to support the development of an economically viable High Speed Civil Transport (HSCT) aircraft. To meet these objectives, papers were presented by representative from NASA Langley, Ames, and Lewis Research Centers; Boeing, McDonnell Douglas, Northrop-Grumman, Lockheed-Martin, Vigyan, Analytical Services, Dynacs, and RIACS.

Applied aerodynamics: Challenges and expectations

NASA Technical Reports Server (NTRS)

Peterson, Victor L.; Smith, Charles A.

1993-01-01

Aerospace is the leading positive contributor to this country's balance of trade, derived largely from the sale of U.S. commercial aircraft around the world. This powerfully favorable economic situation is being threatened in two ways: (1) the U.S. portion of the commercial transport market is decreasing, even though the worldwide market is projected to increase substantially; and (2) expenditures are decreasing for military aircraft, which often serve as proving grounds for advanced aircraft technology. To retain a major share of the world market for commercial aircraft and continue to provide military aircraft with unsurpassed performance, the U.S. aerospace industry faces many technological challenges. The field of applied aerodynamics is necessarily a major contributor to efforts aimed at meeting these technological challenges. A number of emerging research results that will provide new opportunities for applied aerodynamicists are discussed. Some of these have great potential for maintaining the high value of contributions from applied aerodynamics in the relatively near future. Over time, however, the value of these contributions will diminish greatly unless substantial investments continue to be made in basic and applied research efforts. The focus: to increase understanding of fluid dynamic phenomena, identify new aerodynamic concepts, and provide validated advanced technology for future aircraft.

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.

Aerodynamic optimization studies on advanced architecture computers

NASA Technical Reports Server (NTRS)

Chawla, Kalpana

1995-01-01

The approach to carrying out multi-discipline aerospace design studies in the future, especially in massively parallel computing environments, comprises of choosing (1) suitable solvers to compute solutions to equations characterizing a discipline, and (2) efficient optimization methods. In addition, for aerodynamic optimization problems, (3) smart methodologies must be selected to modify the surface shape. In this research effort, a 'direct' optimization method is implemented on the Cray C-90 to improve aerodynamic design. It is coupled with an existing implicit Navier-Stokes solver, OVERFLOW, to compute flow solutions. The optimization method is chosen such that it can accomodate multi-discipline optimization in future computations. In the work , however, only single discipline aerodynamic optimization will be included.

Nonlinear Unsteady Aerodynamic Modeling Using Wind Tunnel and Computational Data

NASA Technical Reports Server (NTRS)

Murphy, Patrick C.; Klein, Vladislav; Frink, Neal T.

2016-01-01

Extensions to conventional aircraft aerodynamic models are required to adequately predict responses when nonlinear unsteady flight regimes are encountered, especially at high incidence angles and under maneuvering conditions. For a number of reasons, such as loss of control, both military and civilian aircraft may extend beyond normal and benign aerodynamic flight conditions. In addition, military applications may require controlled flight beyond the normal envelope, and civilian flight may require adequate recovery or prevention methods from these adverse conditions. These requirements have led to the development of more general aerodynamic modeling methods and provided impetus for researchers to improve both techniques and the degree of collaboration between analytical and experimental research efforts. In addition to more general mathematical model structures, dynamic test methods have been designed to provide sufficient information to allow model identification. This paper summarizes research to develop a modeling methodology appropriate for modeling aircraft aerodynamics that include nonlinear unsteady behaviors using both experimental and computational test methods. This work was done at Langley Research Center, primarily under the NASA Aviation Safety Program, to address aircraft loss of control, prevention, and recovery aerodynamics.

Control of helicopter rotorblade aerodynamics

NASA Technical Reports Server (NTRS)

Fabunmi, James A.

1991-01-01

The results of a feasibility study of a method for controlling the aerodynamics of helicopter rotorblades using stacks of piezoelectric ceramic plates are presented. A resonant mechanism is proposed for the amplification of the displacements produced by the stack. This motion is then converted into linear displacement for the actuation of the servoflap of the blades. A design which emulates the actuation of the servoflap on the Kaman SH-2F is used to demonstrate the fact that such a system can be designed to produce the necessary forces and velocities needed to control the aerodynamics of the rotorblades of such a helicopter. Estimates of the electrical power requirements are also presented. A Small Business Innovation Research (SBIR) Phase 2 Program is suggested, whereby a bench-top prototype of the device can be built and tested. A collaborative effort between AEDAR Corporation and Kaman Aerospace Corporation is anticipated for future effort on this project.

Numerical aerodynamic simulation program long haul communications prototype

NASA Technical Reports Server (NTRS)

Cmaylo, Bohden K.; Foo, Lee

1987-01-01

This document is a report of the Numerical Aerodynamic Simulation (NAS) Long Haul Communications Prototype (LHCP). It describes the accomplishments of the LHCP group, presents the results from all LHCP experiments and testing activities, makes recommendations for present and future LHCP activities, and evaluates the remote workstation accesses from Langley Research Center, Lewis Research Center, and Colorado State University to Ames Research Center. The report is the final effort of the Long Haul (Wideband) Communications Prototype Plan (PT-1133-02-N00), 3 October 1985, which defined the requirements for the development, test, and operation of the LHCP network and was the plan used to evaluate the remote user bandwidth requirements for the Numerical Aerodynamic Simulation Processing System Network.

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.

Tabulation of data from the tip aerodynamics and acoustics test

NASA Technical Reports Server (NTRS)

Cross, Jeffrey L.; Tu, Wilson

1990-01-01

In a continuing effort to understand helicopter rotor tip aerodynamics and acoustics, researchers at Ames Research Center conducted a flight test. The test was performed using the NASA White Cobra and a set of highly instrumented blades. Tabular and graphic summaries of two data subsets from the Tip Aerodynamics and Acoustics Test are given. The data presented are for airloads, blade structural loads, blade vibrations, with summary tables of the aircraft states for each test point. The tabular data consist of the first 15 harmonics only, whereas the plots contain the entire measured frequency content.

Flow Quality Measurements in an Aerodynamic Model of NASA Lewis' Icing Research Tunnel

NASA Technical Reports Server (NTRS)

Canacci, Victor A.; Gonsalez, Jose C.

1999-01-01

As part of an ongoing effort to improve the aerodynamic flow characteristics of the Icing Research Tunnel (IRT), a modular scale model of the facility was fabricated. This 1/10th-scale model was used to gain further understanding of the flow characteristics in the IRT. The model was outfitted with instrumentation and data acquisition systems to determine pressures, velocities, and flow angles in the settling chamber and test section. Parametric flow quality studies involving the insertion and removal of a model of the IRT's distinctive heat exchanger (cooler) and/or of a honeycomb in the settling chamber were performed. These experiments illustrate the resulting improvement or degradation in flow quality.

Direct use of linear time-domain aerodynamics in aeroservoelastic analysis: Aerodynamic model

NASA Technical Reports Server (NTRS)

Woods, J. A.; Gilbert, Michael G.

1990-01-01

The work presented here is the first part of a continuing effort to expand existing capabilities in aeroelasticity by developing the methodology which is necessary to utilize unsteady time-domain aerodynamics directly in aeroservoelastic design and analysis. The ultimate objective is to define a fully integrated state-space model of an aeroelastic vehicle's aerodynamics, structure and controls which may be used to efficiently determine the vehicle's aeroservoelastic stability. Here, the current status of developing a state-space model for linear or near-linear time-domain indicial aerodynamic forces is presented.

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.

Aerodynamic Database Development for the Hyper-X Airframe Integrated Scramjet Propulsion Experiments

NASA Technical Reports Server (NTRS)

Engelund, Walter C.; Holland, Scott D.; Cockrell, Charles E., Jr.; Bittner, Robert D.

2000-01-01

This paper provides an overview of the activities associated with the aerodynamic database which is being developed in support of NASA's Hyper-X scramjet flight experiments. Three flight tests are planned as part of the Hyper-X program. Each will utilize a small, nonrecoverable research vehicle with an airframe integrated scramjet propulsion engine. The research vehicles will be individually rocket boosted to the scramjet engine test points at Mach 7 and Mach 10. The research vehicles will then separate from the first stage booster vehicle and the scramjet engine test will be conducted prior to the terminal decent phase of the flight. An overview is provided of the activities associated with the development of the Hyper-X aerodynamic database, including wind tunnel test activities and parallel CFD analysis efforts for all phases of the Hyper-X flight tests. A brief summary of the Hyper-X research vehicle aerodynamic characteristics is provided, including the direct and indirect effects of the airframe integrated scramjet propulsion system operation on the basic airframe stability and control characteristics. Brief comments on the planned post flight data analysis efforts are also included.

Experimental and analytical research on the aerodynamics of wind driven turbines. Final report

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

Rohrbach, C.; Wainauski, H.; Worobel, R.

1977-12-01

This aerodynamic research program was aimed at providing a reliable, comprehensive data base on a series of wind turbine models covering a broad range of the prime aerodynamic and geometric variables. Such data obtained under controlled laboratory conditions on turbines designed by the same method, of the same size, and tested in the same wind tunnel had not been available in the literature. Moreover, this research program was further aimed at providing a basis for evaluating the adequacy of existing wind turbine aerodynamic design and performance methodology, for assessing the potential of recent advanced theories and for providing a basismore » for further method development and refinement.« less

Fairing Well: Aerodynamic Truck Research at NASA Dryden Flight Research Center. From Shoebox to Bat Truck and Beyond

NASA Technical Reports Server (NTRS)

Gelzer, Christian

2011-01-01

In 1973 engineers at Dryden began investigating ways to reduce aerodynamic drag on land vehicles. They began with a delivery van whose shape they changed dramatically, finally reducing its aerodynamic drag by more than 5 percent. They then turned their attention to tracator-trailers, modifying a cab-over and reducing its aerodynamic drag by nearly 25 percent. Further research identified additional areas worth attention, but in the intervening decades few of those changes have appeared.

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.

Experimental Aerodynamic Characteristics of a Joined-wing Research Aircraft Configuration

NASA Technical Reports Server (NTRS)

Smith, Stephen C.; Stonum, Ronald K.

1989-01-01

A wind-tunnel test was conducted at Ames Research Center to measure the aerodynamic characteristics of a joined-wing research aircraft (JWRA). This aircraft was designed to utilize the fuselage and engines of the existing NASA AD-1 aircraft. The JWRA was designed to have removable outer wing panels to represent three different configurations with the interwing joint at different fractions of the wing span. A one-sixth-scale wind-tunnel model of all three configurations of the JWRA was tested in the Ames 12-Foot Pressure Wind Tunnel to measure aerodynamic performance, stability, and control characteristics. The results of these tests are presented. Longitudinal and lateral-directional characteristics were measured over an angle of attack range of -7 to 14 deg and over an angle of sideslip range of -5 to +2.5 deg at a Mach number of 0.35 and a Reynolds number of 2.2x10(6)/ft. Various combinations of deflected control surfaces were tested to measure the effectiveness and impact on stability of several control surface arrangements. In addition, the effects on stall and post-stall aerodynamic characteristics from small leading-edge devices called vortilons were measured. The results of these tests indicate that the JWRA had very good aerodynamic performance and acceptable stability and control throughout its flight envelope. The vortilons produced a profound improvement in the stall and post-stall characteristics with no measurable effects on cruise performance.

Role of computational fluid dynamics in unsteady aerodynamics for aeroelasticity

NASA Technical Reports Server (NTRS)

Guruswamy, Guru P.; Goorjian, Peter M.

1989-01-01

In the last two decades there have been extensive developments in computational unsteady transonic aerodynamics. Such developments are essential since the transonic regime plays an important role in the design of modern aircraft. Therefore, there has been a large effort to develop computational tools with which to accurately perform flutter analysis at transonic speeds. In the area of Computational Fluid Dynamics (CFD), unsteady transonic aerodynamics are characterized by the feature of modeling the motion of shock waves over aerodynamic bodies, such as wings. This modeling requires the solution of nonlinear partial differential equations. Most advanced codes such as XTRAN3S use the transonic small perturbation equation. Currently, XTRAN3S is being used for generic research in unsteady aerodynamics and aeroelasticity of almost full aircraft configurations. Use of Euler/Navier Stokes equations for simple typical sections has just begun. A brief history of the development of CFD for aeroelastic applications is summarized. The development of unsteady transonic aerodynamics and aeroelasticity are also summarized.

CFD research, parallel computation and aerodynamic optimization

NASA Technical Reports Server (NTRS)

Ryan, James S.

1995-01-01

Over five years of research in Computational Fluid Dynamics and its applications are covered in this report. Using CFD as an established tool, aerodynamic optimization on parallel architectures is explored. The objective of this work is to provide better tools to vehicle designers. Submarine design requires accurate force and moment calculations in flow with thick boundary layers and large separated vortices. Low noise production is critical, so flow into the propulsor region must be predicted accurately. The High Speed Civil Transport (HSCT) has been the subject of recent work. This vehicle is to be a passenger vehicle with the capability of cutting overseas flight times by more than half. A successful design must surpass the performance of comparable planes. Fuel economy, other operational costs, environmental impact, and range must all be improved substantially. For all these reasons, improved design tools are required, and these tools must eventually integrate optimization, external aerodynamics, propulsion, structures, heat transfer and other disciplines.

Freight Wing Trailer Aerodynamics

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

Graham, Sean; Bigatel, Patrick

2004-10-17

Freight Wing Incorporated utilized the opportunity presented by this DOE category one Inventions and Innovations grant to successfully research, develop, test, patent, market, and sell innovative fuel and emissions saving aerodynamic attachments for the trucking industry. A great deal of past scientific research has demonstrated that streamlining box shaped semi-trailers can significantly reduce a truck's fuel consumption. However, significant design challenges have prevented past concepts from meeting industry needs. Market research early in this project revealed the demands of truck fleet operators regarding aerodynamic attachments. Products must not only save fuel, but cannot interfere with the operation of the truck,more » require significant maintenance, add significant weight, and must be extremely durable. Furthermore, SAE/TMC J1321 tests performed by a respected independent laboratory are necessary for large fleets to even consider purchase. Freight Wing used this information to create a system of three practical aerodynamic attachments for the front, rear and undercarriage of standard semi trailers. SAE/TMC J1321 Type II tests preformed by the Transportation Research Center (TRC) demonstrated a 7% improvement to fuel economy with all three products. If Freight Wing is successful in its continued efforts to gain market penetration, the energy and environmental savings would be considerable. Each truck outfitted saves approximately 1,100 gallons of fuel every 100,000 miles, which prevents over 12 tons of CO2 from entering the atmosphere. If all applicable trailers used the technology, the country could save approximately 1.8 billion gallons of diesel fuel, 18 million tons of emissions and 3.6 billion dollars annually.« less

Algorithmic Enhancements for Unsteady Aerodynamics and Combustion Applications

NASA Technical Reports Server (NTRS)

Venkateswaran, Sankaran; Olsen, Michael (Technical Monitor)

2001-01-01

Research in the FY01 focused on the analysis and development of enhanced algorithms for unsteady aerodynamics and chemically reacting flowfields. The research was performed in support of NASA Ames' efforts to improve the capabilities of the in-house computational fluid dynamics code, OVERFLOW. Specifically, the research was focused on the four areas: (1) investigation of stagnation region effects; (2) unsteady preconditioning dual-time procedures; (3) dissipation formulation for combustion; and (4) time-stepping methods for combustion.

NASA aerodynamics program

NASA Technical Reports Server (NTRS)

Williams, Louis J.; Hessenius, Kristin A.; Corsiglia, Victor R.; Hicks, Gary; Richardson, Pamela F.; Unger, George; Neumann, Benjamin; Moss, Jim

1992-01-01

The annual accomplishments is reviewed for the Aerodynamics Division during FY 1991. The program includes both fundamental and applied research directed at the full spectrum of aerospace vehicles, from rotorcraft to planetary entry probes. A comprehensive review is presented of the following aerodynamics elements: computational methods and applications; CFD validation; transition and turbulence physics; numerical aerodynamic simulation; test techniques and instrumentation; configuration aerodynamics; aeroacoustics; aerothermodynamics; hypersonics; subsonics; fighter/attack aircraft and rotorcraft.

History of the numerical aerodynamic simulation program

NASA Technical Reports Server (NTRS)

Peterson, Victor L.; Ballhaus, William F., Jr.

1987-01-01

The Numerical Aerodynamic Simulation (NAS) program has reached a milestone with the completion of the initial operating configuration of the NAS Processing System Network. This achievement is the first major milestone in the continuing effort to provide a state-of-the-art supercomputer facility for the national aerospace community and to serve as a pathfinder for the development and use of future supercomputer systems. The underlying factors that motivated the initiation of the program are first identified and then discussed. These include the emergence and evolution of computational aerodynamics as a powerful new capability in aerodynamics research and development, the computer power required for advances in the discipline, the complementary nature of computation and wind tunnel testing, and the need for the government to play a pathfinding role in the development and use of large-scale scientific computing systems. Finally, the history of the NAS program is traced from its inception in 1975 to the present time.

Modeling the High Speed Research Cycle 2B Longitudinal Aerodynamic Database Using Multivariate Orthogonal Functions

NASA Technical Reports Server (NTRS)

Morelli, E. A.; Proffitt, M. S.

1999-01-01

The data for longitudinal non-dimensional, aerodynamic coefficients in the High Speed Research Cycle 2B aerodynamic database were modeled using polynomial expressions identified with an orthogonal function modeling technique. The discrepancy between the tabular aerodynamic data and the polynomial models was tested and shown to be less than 15 percent for drag, lift, and pitching moment coefficients over the entire flight envelope. Most of this discrepancy was traced to smoothing local measurement noise and to the omission of mass case 5 data in the modeling process. A simulation check case showed that the polynomial models provided a compact and accurate representation of the nonlinear aerodynamic dependencies contained in the HSR Cycle 2B tabular aerodynamic database.

Future Computer Requirements for Computational Aerodynamics

NASA Technical Reports Server (NTRS)

1978-01-01

Recent advances in computational aerodynamics are discussed as well as motivations for and potential benefits of a National Aerodynamic Simulation Facility having the capability to solve fluid dynamic equations at speeds two to three orders of magnitude faster than presently possible with general computers. Two contracted efforts to define processor architectures for such a facility are summarized.

Classical Aerodynamic Theory

NASA Technical Reports Server (NTRS)

Jones, R. T. (Compiler)

1979-01-01

A collection of papers on modern theoretical aerodynamics is presented. Included are theories of incompressible potential flow and research on the aerodynamic forces on wing and wing sections of aircraft and on airship hulls.

Status Report for the Hypervelocity Free-Flight Aerodynamic Facility

NASA Technical Reports Server (NTRS)

Cornelison, Charles J.; Arnold, James O. (Technical Monitor)

1997-01-01

The Hypervelocity Free-Flight Aerodynamic Facility, located at Ames Research Center, is NASA's only aeroballistic facility. During 1997, its model imaging and time history recording systems were the focus of a major refurbishment effort. Specifically the model detection, spark gap (light source); Kerr cell (high speed shuttering); and interval timer sub-systems were inspected, repaired, modified or replaced as required. These refurbishment efforts have fully restored the HFFAF's capabilities to a much better condition, comparable to what it was 15 years ago. Details of this refurbishment effort along with a brief discussion of future upgrade plans are presented.

Developments in steady and unsteady aerodynamics for use in aeroelastic analysis and design. [for supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Yates, E. C., Jr.; Bland, S. R.

1976-01-01

A review is given of seven research projects which are aimed at improving the generality, accuracy, and computational efficiency of steady and unsteady aerodynamic theory for use in aeroelastic analysis and design. These projects indicate three major thrusts of current research efforts: (1) more realistic representation of steady and unsteady subsonic and supersonic loads on aircraft configurations of general shape with emphasis on structural-design applications, (2) unsteady aerodynamics for application in active-controls analyses, and (3) unsteady aerodynamics for the frequently critical transonic speed range. The review of each project includes theoretical background, description of capabilities, results of application, current status, and plans for further development and use.

Aerodynamic Design of a Four-Stage Low-Speed Axial Compressor for Cantilevered Stator Research

NASA Astrophysics Data System (ADS)

Wallace, James N.

This research is focused on the baseline aerodynamic design of a four-stage low-speed axial compressor with the intent to achieve similarity of cantilevered stator hub leakage flows with those in the rear stages of Siemens large gas turbine compressors. The baseline airfoil design is to act as a comparison for all future research completed in the low speed compressor and, therefore, will not include possible future research topics such as 3-D airfoil geometry or end-wall contouring. Following the design of the airfoils is the aerodynamic design of the facility including the inlet and exhaust. These components were designed to eliminate interactions of the compressor with the facility and to accommodate instrumentation. A baseline set of aerodynamic instrumentation is then suggested to characterize compressor performance. Fully 3-D steady CFD was used extensively during the design of both the facility and the compressor, as well as determining the locations and types of instrumentation.

Powered-Lift Aerodynamics and Acoustics. [conferences

NASA Technical Reports Server (NTRS)

1976-01-01

Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.

Rotorcraft research testing in the National Full-Scale Aerodynamics Complex at NASA Ames Research Center

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

Coupled Aerodynamic-Thermal-Structural (CATS) Analysis

NASA Technical Reports Server (NTRS)

1995-01-01

Coupled Aerodynamic-Thermal-Structural (CATS) Analysis is a focused effort within the Numerical Propulsion System Simulation (NPSS) program to streamline multidisciplinary analysis of aeropropulsion components and assemblies. Multidisciplinary analysis of axial-flow compressor performance has been selected for the initial focus of this project. CATS will permit more accurate compressor system analysis by enabling users to include thermal and mechanical effects as an integral part of the aerodynamic analysis of the compressor primary flowpath. Thus, critical details, such as the variation of blade tip clearances and the deformation of the flowpath geometry, can be more accurately modeled and included in the aerodynamic analyses. The benefits of this coupled analysis capability are (1) performance and stall line predictions are improved by the inclusion of tip clearances and hot geometries, (2) design alternatives can be readily analyzed, and (3) higher fidelity analysis by researchers in various disciplines is possible. The goals for this project are a 10-percent improvement in stall margin predictions and a 2:1 speed-up in multidisciplinary analysis times. Working cooperatively with Pratt & Whitney, the Lewis CATS team defined the engineering processes and identified the software products necessary for streamlining these processes. The basic approach is to integrate the aerodynamic, thermal, and structural computational analyses by using data management and Non-Uniform Rational B-Splines (NURBS) based data mapping. Five software products have been defined for this task: (1) a primary flowpath data mapper, (2) a two-dimensional data mapper, (3) a database interface, (4) a blade structural pre- and post-processor, and (5) a computational fluid dynamics code for aerothermal analysis of the drum rotor. Thus far (1) a cooperative agreement has been established with Pratt & Whitney, (2) a Primary Flowpath Data Mapper has been prototyped and delivered to General Electric

An overview of the fundamental aerodynamics branch's research activities in wing leading-edge vortex flows at supersonic speeds

NASA Technical Reports Server (NTRS)

Miller, D. S.; Wood, R. M.; Covell, P. F.

1986-01-01

For the past 3 years, a research program pertaining to the study of wing leading edge vortices at supersonic speeds has been conducted in the Fundamental Aerodynamics Branch of the High-Speed Aerodynamics Division at the Langley Research Center. The purpose of the research is to provide an understanding of the factors governing the formation and the control of wing leading-edge vortices and to evaluate the use of these vortices for improving supersonic aerodynamic performance. The studies include both experimental and theoretical investigations and focus primarily on planform, thickness and camber effects for delta wings. An overview of this research activity is presented.

27. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH ...

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

27. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH LABORATORY, BUILDING 25C, WHICH REPLACED THE 10-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

26. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH ...

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

26. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH LABORATORY, BUILDING 25C, WHICH REPLACED THE 10-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

28. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH ...

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

28. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH LABORATORY, BUILDING 25C, WHICH REPLACED THE 10-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

Hyper-X Research Vehicle (HXRV) Experimental Aerodynamics Test Program Overview

NASA Technical Reports Server (NTRS)

Holland, Scott D.; Woods, William C.; Engelund, Walter C.

2000-01-01

This paper provides an overview of the experimental aerodynamics test program to ensure mission success for the autonomous flight of the Hyper-X Research Vehicle (HXRV). The HXRV is a 12-ft long, 2700 lb lifting body technology demonstrator designed to flight demonstrate for the first time a fully airframe integrated scramjet propulsion system. Three flights are currently planned, two at Mach 7 and one at Mach 10, beginning in the fall of 2000. The research vehicles will be boosted to the prescribed scramjet engine test point where they will separate from the booster, stabilize. and initiate engine test. Following 5+ seconds of powered flight and 15 seconds of cowl-open tares, the cowl will close and the vehicle will fly a controlled deceleration trajectory which includes numerous control doublets for in-flight aerodynamic parameter identification. This paper reviews the preflight testing activities, wind tunnel models, test rationale. risk reduction activities, and sample results from wind tunnel tests supporting the flight trajectory of the HXRV from hypersonic engine test point through subsonic flight termination.

Hyper-X Research Vehicle (HXRV) Experimental Aerodynamics Test Program Overview

NASA Technical Reports Server (NTRS)

Holland, Scott D.; Woods, William C.; Engelund, Walter C.

2000-01-01

This paper provides an overview of the experimental aerodynamics test program to ensure mission success for the autonomous flight of the Hyper-X Research Vehicle (HXRV). The HXRV is a 12-ft long, 2700 lb lifting body technology demonstrator designed to flight demonstrate for the first time a fully airframe integrated scramjet propulsion system. Three flights are currently planned, two at Mach 7 and one at Mach 10, beginning in the fall of 2000. The research vehicles will be boosted to the prescribed scramjet engine test point where they will separate from the booster, stabilize, and initiate engine test. Following 5+ seconds of powered flight and 15 seconds of cow-open tares, the cowl will close and the vehicle will fly a controlled deceleration trajectory which includes numerous control doublets for in-flight aerodynamic parameter identification. This paper reviews the preflight testing activities, wind tunnel models, test rationale, risk reduction activities, and sample results from wind tunnel tests supporting the flight trajectory of the HXRV from hypersonic engine test point through subsonic flight termination.

Aerodynamic design trends for commercial aircraft

NASA Technical Reports Server (NTRS)

Hilbig, R.; Koerner, H.

1986-01-01

Recent research on advanced-configuration commercial aircraft at DFVLR is surveyed, with a focus on aerodynamic approaches to improved performance. Topics examined include transonic wings with variable camber or shock/boundary-layer control, wings with reduced friction drag or laminarized flow, prop-fan propulsion, and unusual configurations or wing profiles. Drawings, diagrams, and graphs of predicted performance are provided, and the need for extensive development efforts using powerful computer facilities, high-speed and low-speed wind tunnels, and flight tests of models (mounted on specially designed carrier aircraft) is indicated.

Estimating Vocal Effort from the Aerodynamics of Labial Fricatives: A Feasibility Study.

PubMed

Meynadier, Yohann; El Hajj, Anita; Pitermann, Michel; Legou, Thierry; Giovanni, Antoine

2017-09-12

Vocal effort in loud voice is produced with increased subglottal pressure during vowels and increased supraglottal pressure during consonants. In the paper, our main objective is to check whether it was supported by a parallel increase in the airflow resistance of the laryngeal articulator and of the supralaryngeal articulator, here the lips. For this comparison, our choice fell on the fricative consonants, as their production allows perfectly synchronous air pressure and airflow measurements. Also, the calculation of the real instantaneous aerodynamic resistance is possible with fricatives-as it is with vowels-whereas it is not possible with plosives. The present feasibility study on a healthy subject is based on direct subglottal and intraoral pressures and airflow measured for /f/ or /v/ and from the contiguous vowel produced in VCVCV nonsense words at different levels of intensity. The results support that the airflow resistances at the lips and that at the larynx are quite parallel. The airflow resistance at the lips during labial fricative production could provide a good picture of the laryngeal resistance during the production of continuous speech. This suggests clinical applications using both noninvasive inferred measurements of subglottal pressure variation and direct noninferred airflow measurements from more natural speech production tasks. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

A smoke generator system for aerodynamic flight research

NASA Technical Reports Server (NTRS)

Richwine, David M.; Curry, Robert E.; Tracy, Gene V.

1989-01-01

A smoke generator system was developed for in-flight vortex flow studies on the F-18 high alpha research vehicle (HARV). The development process included conceptual design, a survey of existing systems, component testing, detailed design, fabrication, and functional flight testing. Housed in the forebody of the aircraft, the final system consists of multiple pyrotechnic smoke cartridges which can be fired simultaneously or in sequence. The smoke produced is ducted to desired locations on the aircraft surface. The smoke generator system (SGS) has been used successfully to identify vortex core and core breakdown locations as functions of flight condition. Although developed for a specific vehicle, this concept may be useful for other aerodynamic flight research which requires the visualization of local flows.

Computational aerodynamics development and outlook /Dryden Lecture in Research for 1979/

NASA Technical Reports Server (NTRS)

Chapman, D. R.

1979-01-01

Some past developments and current examples of computational aerodynamics are briefly reviewed. An assessment is made of the requirements on future computer memory and speed imposed by advanced numerical simulations, giving emphasis to the Reynolds averaged Navier-Stokes equations and to turbulent eddy simulations. Experimental scales of turbulence structure are used to determine the mesh spacings required to adequately resolve turbulent energy and shear. Assessment also is made of the changing market environment for developing future large computers, and of the projections of micro-electronics memory and logic technology that affect future computer capability. From the two assessments, estimates are formed of the future time scale in which various advanced types of aerodynamic flow simulations could become feasible. Areas of research judged especially relevant to future developments are noted.

Configuration aerodynamics

NASA Technical Reports Server (NTRS)

Polhamus, E. C.; Gloss, B. B.

1981-01-01

Static aerodynamic research related to aircraft configurations in their cruise or combat modes is discussed. Subsonic transport aircraft, transonic tactical aircraft, and slender wing aircraft are considered. The status and plans of Langley's NTF configuration research program are reviewed. Recommendations for near term configuration research are made.

Aerodynamics of advanced axial-flow turbomachinery

NASA Technical Reports Server (NTRS)

Serovy, G. K.; Kavanagh, P.; Kiishi, T. H.

1980-01-01

A multi-task research program on aerodynamic problems in advanced axial-flow turbomachine configurations was carried out at Iowa State University. The elements of this program were intended to contribute directly to the improvement of compressor, fan, and turbine design methods. Experimental efforts in intra-passage flow pattern measurements, unsteady blade row interaction, and control of secondary flow are included, along with computational work on inviscid-viscous interaction blade passage flow techniques. This final report summarizes the results of this program and indicates directions which might be taken in following up these results in future work. In a separate task a study was made of existing turbomachinery research programs and facilities in universities located in the United States. Some potentially significant research topics are discussed which might be successfully attacked in the university atmosphere.

A Synthesis of Hybrid RANS/LES CFD Results for F-16XL Aircraft Aerodynamics

NASA Technical Reports Server (NTRS)

Luckring, James M.; Park, Michael A.; Hitzel, Stephan M.; Jirasek, Adam; Lofthouse, Andrew J.; Morton, Scott A.; McDaniel, David R.; Rizzi, Arthur M.

2015-01-01

A synthesis is presented of recent numerical predictions for the F-16XL aircraft flow fields and aerodynamics. The computational results were all performed with hybrid RANS/LES formulations, with an emphasis on unsteady flows and subsequent aerodynamics, and results from five computational methods are included. The work was focused on one particular low-speed, high angle-of-attack flight test condition, and comparisons against flight-test data are included. This work represents the third coordinated effort using the F-16XL aircraft, and a unique flight-test data set, to advance our knowledge of slender airframe aerodynamics as well as our capability for predicting these aerodynamics with advanced CFD formulations. The prior efforts were identified as Cranked Arrow Wing Aerodynamics Project International, with the acronyms CAWAPI and CAWAPI-2. All information in this paper is in the public domain.

Using the HARV simulation aerodynamic model to determine forebody strake aerodynamic coefficients from flight data

NASA Technical Reports Server (NTRS)

Messina, Michael D.

1995-01-01

The method described in this report is intended to present an overview of a process developed to extract the forebody aerodynamic increments from flight tests. The process to determine the aerodynamic increments (rolling pitching, and yawing moments, Cl, Cm, Cn, respectively) for the forebody strake controllers added to the F/A - 18 High Alpha Research Vehicle (HARV) aircraft was developed to validate the forebody strake aerodynamic model used in simulation.

Tip aerodynamics and acoustics test: A report and data survey

NASA Technical Reports Server (NTRS)

Cross, Jeffrey L.; Watts, Michael E.

1988-01-01

In a continuing effort to understand helicopter rotor tip aerodynamics and acoustics, a flight test was conducted by NASA Ames Research Center. The test was performed using the NASA White Cobra and a set of highly instrumented blades. All aspects of the flight test instrumentation and test procedures are explained. Additionally, complete data sets for selected test points are presented and analyzed. Because of the high volume of data acquired, only selected data points are presented. However, access to the entire data set is available to the researcher on request.

Aerodynamic design on high-speed trains

NASA Astrophysics Data System (ADS)

Ding, San-San; Li, Qiang; Tian, Ai-Qin; Du, Jian; Liu, Jia-Li

2016-04-01

Compared with the traditional train, the operational speed of the high-speed train has largely improved, and the dynamic environment of the train has changed from one of mechanical domination to one of aerodynamic domination. The aerodynamic problem has become the key technological challenge of high-speed trains and significantly affects the economy, environment, safety, and comfort. In this paper, the relationships among the aerodynamic design principle, aerodynamic performance indexes, and design variables are first studied, and the research methods of train aerodynamics are proposed, including numerical simulation, a reduced-scale test, and a full-scale test. Technological schemes of train aerodynamics involve the optimization design of the streamlined head and the smooth design of the body surface. Optimization design of the streamlined head includes conception design, project design, numerical simulation, and a reduced-scale test. Smooth design of the body surface is mainly used for the key parts, such as electric-current collecting system, wheel truck compartment, and windshield. The aerodynamic design method established in this paper has been successfully applied to various high-speed trains (CRH380A, CRH380AM, CRH6, CRH2G, and the Standard electric multiple unit (EMU)) that have met expected design objectives. The research results can provide an effective guideline for the aerodynamic design of high-speed trains.

Investigation at near-sonic speed of some effects of humidity on the longitudinal aerodynamic characteristics of an NASA supercritical wing research airplane model

NASA Technical Reports Server (NTRS)

Jordan, F. L., Jr.

1972-01-01

The Langley 8-foot transonic pressure tunnel was used in an effort to determine the effects of humidity at near-sonic speed on the longitudinal aerodynamic characteristics and wing pressure distributions of an area-rule research airplane model with an NASA supercritical wing. Effects of dewpoint at the normal tunnel operating stagnation temperature of 48.9 C (120 F) and effects of stagnation temperature at a relatively high dewpoint of 15.6 C (60 F) were investigated. The test tunnel stagnation pressure was 101 325 N/sq m (1 atmosphere).

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

Recent NASA Research on Aerodynamic Modeling of Post-Stall and Spin Dynamics of Large Transport Airplanes

NASA Technical Reports Server (NTRS)

Murch, Austin M.; Foster, John V.

2007-01-01

A simulation study was conducted to investigate aerodynamic modeling methods for prediction of post-stall flight dynamics of large transport airplanes. The research approach involved integrating dynamic wind tunnel data from rotary balance and forced oscillation testing with static wind tunnel data to predict aerodynamic forces and moments during highly dynamic departure and spin motions. Several state-of-the-art aerodynamic modeling methods were evaluated and predicted flight dynamics using these various approaches were compared. Results showed the different modeling methods had varying effects on the predicted flight dynamics and the differences were most significant during uncoordinated maneuvers. Preliminary wind tunnel validation data indicated the potential of the various methods for predicting steady spin motions.

Airfoil Ice-Accretion Aerodynamics Simulation

NASA Technical Reports Server (NTRS)

Bragg, Michael B.; Broeren, Andy P.; Addy, Harold E.; Potapczuk, Mark G.; Guffond, Didier; Montreuil, E.

2007-01-01

NASA Glenn Research Center, ONERA, and the University of Illinois are conducting a major research program whose goal is to improve our understanding of the aerodynamic scaling of ice accretions on airfoils. The program when it is completed will result in validated scaled simulation methods that produce the essential aerodynamic features of the full-scale iced-airfoil. This research will provide some of the first, high-fidelity, full-scale, iced-airfoil aerodynamic data. An initial study classified ice accretions based on their aerodynamics into four types: roughness, streamwise ice, horn ice, and spanwise-ridge ice. Subscale testing using a NACA 23012 airfoil was performed in the NASA IRT and University of Illinois wind tunnel to better understand the aerodynamics of these ice types and to test various levels of ice simulation fidelity. These studies are briefly reviewed here and have been presented in more detail in other papers. Based on these results, full-scale testing at the ONERA F1 tunnel using cast ice shapes obtained from molds taken in the IRT will provide full-scale iced airfoil data from full-scale ice accretions. Using these data as a baseline, the final step is to validate the simulation methods in scale in the Illinois wind tunnel. Computational ice accretion methods including LEWICE and ONICE have been used to guide the experiments and are briefly described and results shown. When full-scale and simulation aerodynamic results are available, these data will be used to further develop computational tools. Thus the purpose of the paper is to present an overview of the program and key results to date.

Dynamic Soaring: Aerodynamics for Albatrosses

ERIC Educational Resources Information Center

Denny, Mark

2009-01-01

Albatrosses have evolved to soar and glide efficiently. By maximizing their lift-to-drag ratio "L/D", albatrosses can gain energy from the wind and can travel long distances with little effort. We simplify the difficult aerodynamic equations of motion by assuming that albatrosses maintain a constant "L/D". Analytic solutions to the simplified…

Aerodynamic Performance of Hand Launch Glider

NASA Astrophysics Data System (ADS)

Koike, Masaru; Ishii, Mitsuru

In recent years Micro Air Vehicles (MAV) for disaster aerial video are developed vigorously. In order to improve aerodynamic performance of MAV wing performance in low Reynolds numbers (Re) need to be improved, but research on the theme are very rare. In category of Hand Launch Glider, a kind of model aircraft, glide performance are competed, as a result high performance airfoils in Re is around 20,000 are developed. Therefore for MAV's aerodynamic performance improvement airfoils of Hand Launch Gliders should be referred and aerodynamic characteristics of the airfoils desired to be studied. So in this research, aerodynamic characteristics of the gliders are measured in wind tunnel. And also consistency between wind tunnel test and glide test in calm air is examined to confirm reliability of wind tunnel test. Comparison of different airfoils and flow visualization are also performed.

Computational Aerodynamic Simulations of a Spacecraft Cabin Ventilation Fan Design

NASA Technical Reports Server (NTRS)

Tweedt, Daniel L.

2010-01-01

Quieter working environments for astronauts are needed if future long-duration space exploration missions are to be safe and productive. Ventilation and payload cooling fans are known to be dominant sources of noise, with the International Space Station being a good case in point. To address this issue cost effectively, early attention to fan design, selection, and installation has been recommended, leading to an effort by NASA to examine the potential for small-fan noise reduction by improving fan aerodynamic design. As a preliminary part of that effort, the aerodynamics of a cabin ventilation fan designed by Hamilton Sundstrand has been simulated using computational fluid dynamics codes, and the computed solutions analyzed to quantify various aspects of the fan aerodynamics and performance. Four simulations were performed at the design rotational speed: two at the design flow rate and two at off-design flow rates. Following a brief discussion of the computational codes, various aerodynamic- and performance-related quantities derived from the computed flow fields are presented along with relevant flow field details. The results show that the computed fan performance is in generally good agreement with stated design goals.

Aerodynamics Of Missiles: Present And Future

NASA Technical Reports Server (NTRS)

Nielsen, Jack N.

1991-01-01

Paper reviews variety of topics in aerodynamics of missiles. Describes recent developments and suggests areas in which future research fruitful. Emphasis on stability and control of tactical missiles. Aerodynamic problems discussed in general terms without reference to particular missiles.

Application of supercomputers to computational aerodynamics

NASA Technical Reports Server (NTRS)

Peterson, V. L.

1984-01-01

Computers are playing an increasingly important role in the field of aerodynamics such that they now serve as a major complement to wind tunnels in aerospace research and development. Factors pacing advances in computational aerodynamics are identified, including the amount of computational power required to take the next major step in the discipline. Example results obtained from the successively refined forms of the governing equations are discussed, both in the context of levels of computer power required and the degree to which they either further the frontiers of research or apply to problems of practical importance. Finally, the Numerical Aerodynamic Simulation (NAS) Program - with its 1988 target of achieving a sustained computational rate of 1 billion floating point operations per second and operating with a memory of 240 million words - is discussed in terms of its goals and its projected effect on the future of computational aerodynamics.

Aerodynamic characteristics at high angles of attack

NASA Technical Reports Server (NTRS)

Chambers, J. R.

1977-01-01

An overview is presented of the aerodynamic inputs required for analysis of flight dynamics in the high-angle-of-attack regime wherein large-disturbance, nonlinear effects predominate. An outline of the presentation is presented. The discussion includes: (1) some important fundamental phenomena which determine to a large extent 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.

Special opportunities in helicopter aerodynamics

NASA Technical Reports Server (NTRS)

Mccroskey, W. J.

1983-01-01

Aerodynamic research relating to modern helicopters includes the study of three dimensional, unsteady, nonlinear flow fields. A selective review is made of some of the phenomenon that hamper the development of satisfactory engineering prediction techniques, but which provides a rich source of research opportunities: flow separations, compressibility effects, complex vortical wakes, and aerodynamic interference between components. Several examples of work in progress are given, including dynamic stall alleviation, the development of computational methods for transonic flow, rotor-wake predictions, and blade-vortex interactions.

Research and technology, 1990

NASA Technical Reports Server (NTRS)

1990-01-01

Selected research and technology activities at Ames Research Center, including the Moffett Field site and the Dryden Flight Research Facility, are summarized. These accomplishments exemplify the Center's varied and highly productive research efforts for 1990. The activities addressed are under the directories of: (1) aerospace systems which contains aircraft technology, full-scale aerodynamics research, information sciences, aerospace human factors research, and flight systems and simulation research divisions; (2) Dryden flight research facility which contains research engineering division; (3) aerophysics which contains aerodynamics, fluid dynamics, and thermosciences divisions; and (4) space research which contains advanced life support, space projects, earth system science, life science, and space science divisions, and search for extraterrestrial intelligence and space life sciences payloads offices.

Assessing country-level efforts to link research to action.

PubMed Central

Lavis, John N.; Lomas, Jonathan; Hamid, Maimunah; Sewankambo, Nelson K.

2006-01-01

We developed a framework for assessing country-level efforts to link research to action. The framework has four elements. The first element assesses the general climate (how those who fund research, universities, researchers and users of research support or place value on efforts to link research to action). The second element addresses the production of research (how priority setting ensures that users' needs are identified and how scoping reviews, systematic reviews and single studies are undertaken to address these needs). The third element addresses the mix of four clusters of activities used to link research to action. These include push efforts (how strategies are used to support action based on the messages arising from research), efforts to facilitate "user pull" (how "one-stop shopping" is provided for optimally packaged high-quality reviews either alone or as part of a national electronic library for health, how these reviews are profiled during "teachable moments" such as intense media coverage, and how rapid-response units meet users' needs for the best research), "user pull" efforts undertaken by those who use research (how users assess their capacity to use research and how structures and processes are changed to support the use of research) and exchange efforts (how meaningful partnerships between researchers and users help them to jointly ask and answer relevant questions). The fourth element addresses approaches to evaluation (how support is provided for rigorous evaluations of efforts to link research to action). PMID:16917649

New technology in turbine aerodynamics

NASA Technical Reports Server (NTRS)

Glassman, A. J.; Moffitt, T. P.

1972-01-01

A cursory review is presented of some of the recent work that has been done in turbine aerodynamic research at NASA-Lewis Research Center. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. An extensive bibliography is included. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Turbines currently being investigated make use of advanced blading concepts designed to maintain high efficiency under conditions of high aerodynamic loading. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flow fields. The use of these programs for the design and analysis of axial and radial turbines is discussed.

Green Roof Research through EPA's Regional Applied Research Effort

EPA Science Inventory

ABSTRACT The U.S. Environmental Protection Agency’s (EPA) Regional Applied Research Effort (RARE) allows the Regions of the EPA to choose research projects to be performed in partnership with EPA’s Office of Research and Development (ORD). Over the last decade, several green roo...

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.

Integrated aerodynamic-structural design of a forward-swept transport wing

NASA Technical Reports Server (NTRS)

Haftka, Raphael T.; Grossman, Bernard; Kao, Pi-Jen; Polen, David M.; Sobieszczanski-Sobieski, Jaroslaw

1989-01-01

The introduction of composite materials is having a profound effect on aircraft design. Since these materials permit the designer to tailor material properties to improve structural, aerodynamic and acoustic performance, they require an integrated multidisciplinary design process. Futhermore, because of the complexity of the design process, numerical optimization methods are required. The utilization of integrated multidisciplinary design procedures for improving aircraft design is not currently feasible because of software coordination problems and the enormous computational burden. Even with the expected rapid growth of supercomputers and parallel architectures, these tasks will not be practical without the development of efficient methods for cross-disciplinary sensitivities and efficient optimization procedures. The present research is part of an on-going effort which is focused on the processes of simultaneous aerodynamic and structural wing design as a prototype for design integration. A sequence of integrated wing design procedures has been developed in order to investigate various aspects of the design process.

Prediction of Hyper-X Stage Separation Aerodynamics Using CFD

NASA Technical Reports Server (NTRS)

Buning, Pieter G.; Wong, Tin-Chee; Dilley, Arthur D.; Pao, Jenn L.

2000-01-01

The NASA X-43 "Hyper-X" hypersonic research vehicle will be boosted to a Mach 7 flight test condition mounted on the nose of an Orbital Sciences Pegasus launch vehicle. The separation of the research vehicle from the Pegasus presents some unique aerodynamic problems, for which computational fluid dynamics has played a role in the analysis. This paper describes the use of several CFD methods for investigating the aerodynamics of the research and launch vehicles in close proximity. Specifically addressed are unsteady effects, aerodynamic database extrapolation, and differences between wind tunnel and flight environments.

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.

A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research

NASA Technical Reports Server (NTRS)

Coleman, Colin P.

1997-01-01

The recent appearance of the Kamov Ka-50 helicopter and the application of coaxial rotors to unmanned aerial vehicles have renewed international interest in the coaxial rotor configuration. This report addresses the aerodynamic issues peculiar to coaxial rotors by surveying American, Russian, Japanese, British, and German research. (Herein, 'coaxial rotors' refers to helicopter, not propeller, rotors. The intermeshing rotor system was not investigated.) Issues addressed are separation distance, load sharing between rotors, wake structure, solidity effects, swirl recovery, and the effects of having no tail rotor. A general summary of the coaxial rotor configuration explores the configuration's advantages and applications.

Active Control of Aerodynamic Noise Sources

NASA Technical Reports Server (NTRS)

Reynolds, Gregory A.

2001-01-01

Aerodynamic noise sources become important when propulsion noise is relatively low, as during aircraft landing. Under these conditions, aerodynamic noise from high-lift systems can be significant. The research program and accomplishments described here are directed toward reduction of this aerodynamic noise. Progress toward this objective include correction of flow quality in the Low Turbulence Water Channel flow facility, development of a test model and traversing mechanism, and improvement of the data acquisition and flow visualization capabilities in the Aero. & Fluid Dynamics Laboratory. These developments are described in this report.

Improved Aerodynamic Analysis for Hybrid Wing Body Conceptual Design Optimization

NASA Technical Reports Server (NTRS)

Gern, Frank H.

2012-01-01

This paper provides an overview of ongoing efforts to develop, evaluate, and validate different tools for improved aerodynamic modeling and systems analysis of Hybrid Wing Body (HWB) aircraft configurations. Results are being presented for the evaluation of different aerodynamic tools including panel methods, enhanced panel methods with viscous drag prediction, and computational fluid dynamics. Emphasis is placed on proper prediction of aerodynamic loads for structural sizing as well as viscous drag prediction to develop drag polars for HWB conceptual design optimization. Data from transonic wind tunnel tests at the Arnold Engineering Development Center s 16-Foot Transonic Tunnel was used as a reference data set in order to evaluate the accuracy of the aerodynamic tools. Triangularized surface data and Vehicle Sketch Pad (VSP) models of an X-48B 2% scale wind tunnel model were used to generate input and model files for the different analysis tools. In support of ongoing HWB scaling studies within the NASA Environmentally Responsible Aviation (ERA) program, an improved finite element based structural analysis and weight estimation tool for HWB center bodies is currently under development. Aerodynamic results from these analyses are used to provide additional aerodynamic validation data.

Aerodynamic parameters of High-Angle-of attack Research Vehicle (HARV) estimated from flight data

NASA Technical Reports Server (NTRS)

Klein, Vladislav; Ratvasky, Thomas R.; Cobleigh, Brent R.

1990-01-01

Aerodynamic parameters of the High-Angle-of-Attack Research Aircraft (HARV) were estimated from flight data at different values of the angle of attack between 10 degrees and 50 degrees. The main part of the data was obtained from small amplitude longitudinal and lateral maneuvers. A small number of large amplitude maneuvers was also used in the estimation. The measured data were first checked for their compatibility. It was found that the accuracy of air data was degraded by unexplained bias errors. Then, the data were analyzed by a stepwise regression method for obtaining a structure of aerodynamic model equations and least squares parameter estimates. Because of high data collinearity in several maneuvers, some of the longitudinal and all lateral maneuvers were reanalyzed by using two biased estimation techniques, the principal components regression and mixed estimation. The estimated parameters in the form of stability and control derivatives, and aerodynamic coefficients were plotted against the angle of attack and compared with the wind tunnel measurements. The influential parameters are, in general, estimated with acceptable accuracy and most of them are in agreement with wind tunnel results. The simulated responses of the aircraft showed good prediction capabilities of the resulting model.

Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Technology Development Overview

NASA Technical Reports Server (NTRS)

Hughes, Stephen J.; Cheatwood, F. McNeil; Calomino, Anthony M.; Wright, Henry S.; Wusk, Mary E.; Hughes, Monica F.

2013-01-01

The successful flight of the Inflatable Reentry Vehicle Experiment (IRVE)-3 has further demonstrated the potential value of Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. This technology development effort is funded by NASA's Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP). This paper provides an overview of a multi-year HIAD technology development effort, detailing the projects completed to date and the additional testing planned for the future.

A review of turbomachinery blade-row interaction research

NASA Technical Reports Server (NTRS)

Smith, Todd E.

1988-01-01

Analytical and experimental research in the area of unsteady aerodynamics of turbomachinery has conventionally been applied to blading which oscillates when placed in a uniformly flowing fluid. Comparatively less effort has been offered for the study of blading which is subjected to nonuniformities within the flow field. The fluid dynamic environment of a blade-row embedded within multi-stage turbomachines is dominated by such highly unsteady fluid flow conditions. The production of wakes and circumferential pressure variations from adjacent blade-rows causes large unsteady energy transfers between the fluid and the blades. Determination of the forced response of a blade requires the ability to predict the unsteady loads which are induced by these aerodynamic sources. A review of research publications was done to determine recent investigations of the response of turbomachinery blading subjected to aerodynamic excitations. Such excitations are a direct result of the blade-row aerodynamic interaction which occurs between adjacent cascades of blades. The reports and papers reviewed have been organized into areas emphasizing experimental or analytical efforts.

Investigation of Injector Slot Geometry on Curved-Diffuser Aerodynamic Performance

NASA Technical Reports Server (NTRS)

Silva, Odlanier

2004-01-01

The Compressor Branch vision is to be recognized as world-class leaders in research for fluid mechanics of compressors. Its mission is to conduct research and develop technology to advance the state of the art of compressors and transfer new technology to U.S. industries. Maintain partnerships with U.S. industries, universities, and other government organizations. Maintain a balance between customers focused and long range research. Flow control comprises enabling technologies to meet compression system performance requirements driven by emissions and fuel reduction goals (e.g., in UEET), missions (e.g., access-to-space), aerodynamically aggressive vehicle configurations (e.g., UAV and future blended wing body configurations with highly distorted inlets), and cost goals (e.g., in VAATE). The compression system requirements include increased efficiency, power-to-weight, and adaptability (i.e., robustness in terms of wide operability, distortion tolerance, and engine system health and reliability). The compressor flow control task comprises efforts to develop, demonstrate, and transfer adaptive flow control technology to industry to increase aerodynamic loading at current blade row loss levels, to enable adaptive1 y wide operability, and to develop plant models for adaptive compression systems. In this context, flow control is the controlled modification of a flow field by a deliberate means beyond the natural (uncontrolled) shaping of the solid surfaces that define the principal flow path. The objective of the compressor flow control task is to develop and apply techniques that control circulation, aerodynamic blockage, and entropy production in order to enhance the performance and operability of compression systems for advanced aero-propulsion applications. This summer I would be working with a curved-diffuser because it simulates what happens with flow in the stator blades in the compressor. With this experiment I will be doing some data analysis and parametric

Aerodynamic Design Opportunities for Future Supersonic Aircraft

NASA Technical Reports Server (NTRS)

Wood, Richard M.; Bauer, Steven X. S.; Flamm, Jeffrey D.

2002-01-01

A discussion of a diverse set of aerodynamic opportunities to improve the aerodynamic performance of future supersonic aircraft has been presented and discussed. These ideas are offered to the community in a hope that future supersonic vehicle development activities will not be hindered by past efforts. A number of nonlinear flow based drag reduction technologies are presented and discussed. The subject technologies are related to the areas of interference flows, vehicle concepts, vortex flows, wing design, advanced control effectors, and planform design. The authors also discussed the importance of improving the aerodynamic design environment to allow creativity and knowledge greater influence. A review of all of the data presented show that pressure drag reductions on the order of 50 to 60 counts are achievable, compared to a conventional supersonic cruise vehicle, with the application of several of the discussed technologies. These drag reductions would correlate to a 30 to 40% increase in cruise L/D (lift-to-drag ratio) for a commercial supersonic transport.

Lewis icing research tunnel test of the aerodynamic effects of aircraft ground deicing/anti-icing fluids

NASA Technical Reports Server (NTRS)

Runyan, L. James; Zierten, Thomas A.; Hill, Eugene G.; Addy, Harold E., Jr.

1992-01-01

A wind tunnel investigation of the effect of aircraft ground deicing/anti-icing fluids on the aerodynamic characteristics of a Boeing 737-200ADV airplane was conducted. The test was carried out in the NASA Lewis Icing Research Tunnel. Fluids tested include a Newtonian deicing fluid, three non-Newtonian anti-icing fluids commercially available during or before 1988, and eight new experimental non-Newtonian fluids developed by four fluid manufacturers. The results show that fluids remain on the wind after liftoff and cause a measurable lift loss and drag increase. These effects are dependent on the high-lift configuration and on the temperature. For a configuration with a high-lift leading-edge device, the fluid effect is largest at the maximum lift condition. The fluid aerodynamic effects are related to the magnitude of the fluid surface roughness, particularly in the first 30 percent chord. The experimental fluids show a significant reduction in aerodynamic effects.

Aerodynamic Effects of Simulated Ice Accretion on a Generic Transport Model

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Lee, Sam; Shah, Gautam H.; Murphy, Patrick C.

2012-01-01

An experimental research effort was begun to develop a database of airplane aerodynamic characteristics with simulated ice accretion over a large range of incidence and sideslip angles. Wind-tunnel testing was performed at the NASA Langley 12-ft Low-Speed Wind Tunnel using a 3.5 percent scale model of the NASA Langley Generic Transport Model. Aerodynamic data were acquired from a six-component force and moment balance in static-model sweeps from alpha = -5deg to 85deg and beta = -45 deg to 45 deg at a Reynolds number of 0.24 x10(exp 6) and Mach number of 0.06. The 3.5 percent scale GTM was tested in both the clean configuration and with full-span artificial ice shapes attached to the leading edges of the wing, horizontal and vertical tail. Aerodynamic results for the clean airplane configuration compared favorably with similar experiments carried out on a 5.5 percent scale GTM. The addition of the large, glaze-horn type ice shapes did result in an increase in airplane drag coefficient but had little effect on the lift and pitching moment. The lateral-directional characteristics showed mixed results with a small effect of the ice shapes observed in some cases. The flow visualization images revealed the presence and evolution of a spanwise-running vortex on the wing that was the dominant feature of the flowfield for both clean and iced configurations. The lack of ice-induced performance and flowfield effects observed in this effort was likely due to Reynolds number effects for the clean configuration. Estimates of full-scale baseline performance were included in this analysis to illustrate the potential icing effects.

Computational Aerodynamics of Shuttle Orbiter Damage Scenarios in Support of the Columbia Accident Investigation

NASA Technical Reports Server (NTRS)

Bibb, Karen L.; Prabhu, Ramadas K.

2004-01-01

In support of the Columbia Accident Investigation, inviscid computations of the aerodynamic characteristics for various Shuttle Orbiter damage scenarios were performed using the FELISA unstructured CFD solver. Computed delta aerodynamics were compared with the reconstructed delta aerodynamics in order to postulate a progression of damage through the flight trajectory. By performing computations at hypervelocity flight and CF4 tunnel conditions, a bridge was provided between wind tunnel testing in Langley's 20-Inch CF4 facility and the flight environment experienced by Columbia during re-entry. The rapid modeling capability of the unstructured methodology allowed the computational effort to keep pace with the wind tunnel and, at times, guide the wind tunnel efforts. These computations provided a detailed view of the flowfield characteristics and the contribution of orbiter components (such as the vertical tail and wing) to aerodynamic forces and moments that were unavailable from wind tunnel testing. The damage scenarios are grouped into three categories. Initially, single and multiple missing full RCC panels were analyzed to determine the effect of damage location and magnitude on the aerodynamics. Next is a series of cases with progressive damage, increasing in severity, in the region of RCC panel 9. The final group is a set of wing leading edge and windward surface deformations that model possible structural deformation of the wing skin due to internal heating of the wing structure. By matching the aerodynamics from selected damage scenarios to the reconstructed flight aerodynamics, a progression of damage that is consistent with the flight data, debris forensics, and wind tunnel data is postulated.

Aerodynamic potpourri

NASA Technical Reports Server (NTRS)

Wilson, R. E.

1981-01-01

Aerodynamic developments for vertical axis and horizontal axis wind turbines are given that relate to the performance and aerodynamic loading of these machines. Included are: (1) a fixed wake aerodynamic model of the Darrieus vertical axis wind turbine; (2) experimental results that suggest the existence of a laminar flow Darrieus vertical axis turbine; (3) a simple aerodynamic model for the turbulent windmill/vortex ring state of horizontal axis rotors; and (4) a yawing moment of a rigid hub horizontal axis wind turbine that is related to blade coning.

Space Shuttle hypersonic aerodynamic and aerothermodynamic flight research and the comparison to ground test results

NASA Technical Reports Server (NTRS)

Iliff, Kenneth W.; Shafer, Mary F.

1993-01-01

Aerodynamic and aerothermodynamic comparisons between flight and ground test for the Space Shuttle at hypersonic speeds are discussed. All of the comparisons are taken from papers published by researchers active in the Space Shuttle program. The aerodynamic comparisons include stability and control derivatives, center-of-pressure location, and reaction control jet interaction. Comparisons are also discussed for various forms of heating, including catalytic, boundary layer, top centerline, side fuselage, OMS pod, wing leading edge, and shock interaction. The jet interaction and center-of-pressure location flight values exceeded not only the predictions but also the uncertainties of the predictions. Predictions were significantly exceeded for the heating caused by the vortex impingement on the OMS pods and for heating caused by the wing leading-edge shock interaction.

Compendium of NASA Langley reports on hypersonic aerodynamics

NASA Technical Reports Server (NTRS)

Sabo, Frances E.; Cary, Aubrey M.; Lawson, Shirley W.

1987-01-01

Reference is made to papers published by the Langley Research Center in various areas of hypersonic aerodynamics for the period 1950 to 1986. The research work was performed either in-house by the Center staff or by other personnel supported entirely or in part by grants or contracts. Abstracts have been included with the references when available. The references are listed chronologically and are grouped under the following general headings: (1) Aerodynamic Measurements - Single Shapes; (2) Aerodynamic Measurements - Configurations; (3) Aero-Heating; (4) Configuration Studies; (5) Propulsion Integration Experiment; (6) Propulsion Integration - Study; (7) Analysis Methods; (8) Test Techniques; and (9) Airframe Active Cooling Systems.

Air flow testing on aerodynamic truck

NASA Technical Reports Server (NTRS)

1975-01-01

After leasing a cab-over tractor-trailer from a Southern California firm, Dryden researchers added sheet metal modifications like those shown here. They rounded the front corners and edges, and placed a smooth fairing on the cab's roofs and sides extending back to the trailer. During the investigation of truck aerodynamics, the techniques honed in flight research proved highly applicable. By closing the gap between the cab and the trailer, for example, researchers discovered a significant reduction in aerodynamic drag, one resulting in 20 to 25 percent less fuel consumption than the standard design. Many truck manufacturers subsequently incorporated similar modifications on their products.

A collection of flow visualization techniques used in the Aerodynamic Research Branch

NASA Technical Reports Server (NTRS)

1984-01-01

Theoretical and experimental research on unsteady aerodynamic flows is discussed. Complex flow fields that involve separations, vortex interactions, and transonic flow effects were investigated. Flow visualization techniques are used to obtain a global picture of the flow phenomena before detailed quantitative studies are undertaken. A wide variety of methods are used to visualize fluid flow and a sampling of these methods is presented. It is emphasized that the visualization technique is a thorough quantitative analysis and subsequent physical understanding of these flow fields.

Green Roof Research through EPA's Regional Applied Research Effort - slides

EPA Science Inventory

The U.S. Environmental Protection Agency’s (EPA) Regional Applied Research Effort (RARE) allows the Regions of the EPA to choose research projects to be performed in partnership with EPA’s Office of Research and Development (ORD). Over the last decade, several green roof projects...

Aerodynamics and Control of Quadrotors

NASA Astrophysics Data System (ADS)

Bangura, Moses

Quadrotors are aerial vehicles with a four motor-rotor assembly for generating lift and controllability. Their light weight, ease of design and simple dynamics have increased their use in aerial robotics research. There are many quadrotors that are commercially available or under development. Commercial off-the-shelf quadrotors usually lack the ability to be reprogrammed and are unsuitable for use as research platforms. The open-source code developed in this thesis differs from other open-source systems by focusing on the key performance road blocks in implementing high performance experimental quadrotor platforms for research: motor-rotor control for thrust regulation, velocity and attitude estimation, and control for position regulation and trajectory tracking. In all three of these fundamental subsystems, code sub modules for implementation on commonly available hardware are provided. In addition, the thesis provides guidance on scoping and commissioning open-source hardware components to build a custom quadrotor. A key contribution of the thesis is then a design methodology for the development of experimental quadrotor platforms from open-source or commercial off-the-shelf software and hardware components that have active community support. Quadrotors built following the methodology allows the user access to the operation of the subsystems and, in particular, the user can tune the gains of the observers and controllers in order to push the overall system to its performance limits. This enables the quadrotor framework to be used for a variety of applications such as heavy lifting and high performance aggressive manoeuvres by both the hobby and academic communities. To address the question of thrust control, momentum and blade element theories are used to develop aerodynamic models for rotor blades specific to quadrotors. With the aerodynamic models, a novel thrust estimation and control scheme that improves on existing RPM (revolutions per minute) control of

General Aerodynamic Characteristics of a Research Model with High Disk Loading Direct Lifting Fan Mounted in Fuselage

NASA Image and Video Library

1960-10-26

3/4 Low front view of fuselage and fan. Showing jet engine hanging below. Lift fan powered by jet exhaust. General Aerodynamic Characteristics of a Research Model with High Disk Loading Direct Lifting Fan Mounted in Fuselage

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.

Forced response unsteady aerodynamics in a multistage compressor

NASA Astrophysics Data System (ADS)

Capece, Vincent Ralph

The fundamental flow physics of the unsteady aerodynamics associated with forced vibrations in turbomachinery are investigated. Unique data are obtained through a series of experiments in a three stage axial flow research compressor which quantify the unsteady harmonic gust interaction phenomena over a range of operating and geometric conditions at high values of reduced frequency. In these experiments the effects of the following on the stator vane unsteady aerodynamics were quantified: (1) the steady aerodynamic loading, (2) the detailed waveform of the aerodynamic forcing function, including the chordwise and transverse gust components, (3) multistage blade row interactions, and (4) the solidity, ranging from a design value of 1.09 to an isolated airfoil. In addition, the effect of flow separation on the unsteady aerodynamics of an isolated airfoil was also investigated.

Aerodynamic Validation of Emerging Projectile Configurations

DTIC Science & Technology

2011-12-01

was benchmarked against modern aerodynamic prediction programs like ANSYS CFX and Aero-Prediction 09 (AP09). Next, a comparison was made between two...types of angle of attack generation methods in ANSYS CFX . The research then focused on controlled tilting of the projectile’s nose to investigate the...resulting aerodynamic effects. ANSYS CFX was found to provide better agreement with the experimental data than AP09. 14. SUBJECT

Review of aerodynamic design in the Netherlands

NASA Technical Reports Server (NTRS)

Labrujere, Th. E.

1991-01-01

Aerodynamic design activities in the Netherlands, which take place mainly at Fokker, the National Aerospace Laboratory (NLR), and Delft University of Technology (TUD), are discussed. The survey concentrates on the development of the Fokker 100 wing, glider design at TUD, and research at NLR in the field of aerodynamic design. Results are shown to illustrate these activities.

Aerodynamic Interaction Effects of a Helicopter Rotor and Fuselage

NASA Technical Reports Server (NTRS)

Boyd, David D., Jr.

1999-01-01

A three year Cooperative Research Agreements made in each of the three years between the Subsonic Aerodynamics Branch of the NASA Langley Research Center and the Virginia Polytechnic Institute and State University (Va. Tech) has been completed. This document presents results from this three year endeavor. The goal of creating an efficient method to compute unsteady interactional effects between a helicopter rotor and fuselage has been accomplished. This paper also includes appendices to support these findings. The topics are: 1) Rotor-Fuselage Interactions Aerodynamics: An Unsteady Rotor Model; and 2) Rotor/Fuselage Unsteady Interactional Aerodynamics: A New Computational Model.

Computational fluid dynamics at NASA Ames and the numerical aerodynamic simulation program

NASA Technical Reports Server (NTRS)

Peterson, V. L.

1985-01-01

Computers are playing an increasingly important role in the field of aerodynamics such as that they now serve as a major complement to wind tunnels in aerospace research and development. Factors pacing advances in computational aerodynamics are identified, including the amount of computational power required to take the next major step in the discipline. The four main areas of computational aerodynamics research at NASA Ames Research Center which are directed toward extending the state of the art are identified and discussed. Example results obtained from approximate forms of the governing equations are presented and discussed, both in the context of levels of computer power required and the degree to which they either further the frontiers of research or apply to programs of practical importance. Finally, the Numerical Aerodynamic Simulation Program--with its 1988 target of achieving a sustained computational rate of 1 billion floating-point operations per second--is discussed in terms of its goals, status, and its projected effect on the future of computational aerodynamics.

Aerodynamic Simulation of Ice Accretion on Airfoils

NASA Technical Reports Server (NTRS)

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

2011-01-01

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

Unsteady Aerodynamic Force Sensing from Measured Strain

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi

2016-01-01

A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm. A cantilevered rectangular wing built and tested at the NASA Langley Research Center (Hampton, Virginia, USA) in 1959 is used to validate the simple approach. Unsteady aerodynamic forces as well as wing deflections, velocities, accelerations, and strains are computed using the CFL3D computational fluid dynamics (CFD) code and an MSC/NASTRAN code (MSC Software Corporation, Newport Beach, California, USA), and these CFL3D-based results are assumed as measured quantities. Based on the measured strains, wing deflections, velocities, accelerations, and aerodynamic forces are computed using the proposed approach. These computed deflections, velocities, accelerations, and unsteady aerodynamic forces are compared with the CFL3D/NASTRAN-based results. In general, computed aerodynamic forces based on the lifting surface theory in subsonic speeds are in good agreement with the target aerodynamic forces generated using CFL3D code with the Euler equation. Excellent aeroelastic responses are obtained even with unsteady strain data under the signal to noise ratio of -9.8dB. The deflections, velocities, and accelerations at each sensor location are independent of structural and aerodynamic models. Therefore, the distributed strain data together with the current proposed approaches can be used as distributed deflection

Overview of NASA Magnet and Linear Alternator Research Efforts

NASA Astrophysics Data System (ADS)

Geng, Steven M.; Niedra, Janis M.; Schwarze, Gene E.

2005-02-01

The Department of Energy, Lockheed Martin, Stirling Technology Company, and NASA Glenn Research Center are developing a high-efficiency, 110 watt Stirling Radioisotope Generator (SRG110) for NASA Space Science missions. NASA Glenn is conducting in-house research on rare earth permanent magnets and on linear alternators to assist in developing a free-piston Stirling convertor for the SRG110 and for developing advanced technology. The permanent magnet research efforts include magnet characterization, short-term magnet aging tests, and long-term magnet aging tests. Linear alternator research efforts have begun just recently at GRC with the characterization of a moving iron type linear alternator using GRC's alternator test rig. This paper reports on the progress and future plans of GRC's magnet and linear alternator research efforts.

Overview of NASA Magnet and Linear Alternator Research Efforts

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Schwarze, Gene E.; Nieda, Janis M.

2005-01-01

The Department of Energy, Lockheed Martin, Stirling Technology Company, and NASA Glenn Research Center are developing a high-efficiency, 110 watt Stirling Radioisotope Generator (SRG110) for NASA Space Science missions. NASA Glenn is conducting in-house research on rare earth permanent magnets and on linear alternators to assist in developing a free-piston Stirling convertor for the SRG110 and for developing advanced technology. The permanent magnet research efforts include magnet characterization, short-term magnet aging tests, and long-term magnet aging tests. Linear alternator research efforts have begun just recently at GRC with the characterization of a moving iron type linear alternator using GRC's alternator test rig. This paper reports on the progress and future plans of GRC's magnet and linear alternator research efforts.

Modeling Powered Aerodynamics for the Orion Launch Abort Vehicle Aerodynamic Database

NASA Technical Reports Server (NTRS)

Chan, David T.; Walker, Eric L.; Robinson, Philip E.; Wilson, Thomas M.

2011-01-01

Modeling the aerodynamics of the Orion Launch Abort Vehicle (LAV) has presented many technical challenges to the developers of the Orion aerodynamic database. During a launch abort event, the aerodynamic environment around the LAV is very complex as multiple solid rocket plumes interact with each other and the vehicle. It is further complicated by vehicle separation events such as between the LAV and the launch vehicle stack or between the launch abort tower and the crew module. The aerodynamic database for the LAV was developed mainly from wind tunnel tests involving powered jet simulations of the rocket exhaust plumes, supported by computational fluid dynamic simulations. However, limitations in both methods have made it difficult to properly capture the aerodynamics of the LAV in experimental and numerical simulations. These limitations have also influenced decisions regarding the modeling and structure of the aerodynamic database for the LAV and led to compromises and creative solutions. Two database modeling approaches are presented in this paper (incremental aerodynamics and total aerodynamics), with examples showing strengths and weaknesses of each approach. In addition, the unique problems presented to the database developers by the large data space required for modeling a launch abort event illustrate the complexities of working with multi-dimensional data.

Efficient computation of aerodynamic influence coefficients for aeroelastic analysis on a transputer network

NASA Technical Reports Server (NTRS)

Janetzke, David C.; Murthy, Durbha V.

1991-01-01

Aeroelastic analysis is multi-disciplinary and computationally expensive. Hence, it can greatly benefit from parallel processing. As part of an effort to develop an aeroelastic capability on a distributed memory transputer network, a parallel algorithm for the computation of aerodynamic influence coefficients is implemented on a network of 32 transputers. The aerodynamic influence coefficients are calculated using a 3-D unsteady aerodynamic model and a parallel discretization. Efficiencies up to 85 percent were demonstrated using 32 processors. The effect of subtask ordering, problem size, and network topology are presented. A comparison to results on a shared memory computer indicates that higher speedup is achieved on the distributed memory system.

Twenty-five years of aerodynamic research with IR imaging: A survey

NASA Technical Reports Server (NTRS)

Gartenberg, Ehud; Roberts, A. Sidney, Jr.

1991-01-01

Infrared imaging used in aerodynamic research evolved during the last 25 years into a rewarding experimental technique for investigation of body-flow viscous interactions, such as heat flux determination and boundary layer transition. The technique of infrared imaging matched well its capability to produce useful results, with the expansion of testing conditions in the entire spectrum of wind tunnels, from hypersonic high-enthalpy facilities to cryogenic transonic wind tunnels. With unique achievements credited to its past, the current trend suggests a change in attitude towards this technique: from the perception as an exotic, project-oriented tool, to the status of a routine experimental procedure.

Research on inverse, hybrid and optimization problems in engineering sciences with emphasis on turbomachine aerodynamics: Review of Chinese advances

NASA Technical Reports Server (NTRS)

Liu, Gao-Lian

1991-01-01

Advances in inverse design and optimization theory in engineering fields in China are presented. Two original approaches, the image-space approach and the variational approach, are discussed in terms of turbomachine aerodynamic inverse design. Other areas of research in turbomachine aerodynamic inverse design include the improved mean-streamline (stream surface) method and optimization theory based on optimal control. Among the additional engineering fields discussed are the following: the inverse problem of heat conduction, free-surface flow, variational cogeneration of optimal grid and flow field, and optimal meshing theory of gears.

Missile aerodynamics

NASA Technical Reports Server (NTRS)

Nielsen, Jack N.

1988-01-01

The fundamental aerodynamics of slender bodies is examined in the reprint edition of an introductory textbook originally published in 1960. Chapters are devoted to the formulas commonly used in missile aerodynamics; slender-body theory at supersonic and subsonic speeds; vortices in viscid and inviscid flow; wing-body interference; downwash, sidewash, and the wake; wing-tail interference; aerodynamic controls; pressure foredrag, base drag, and skin friction; and stability derivatives. Diagrams, graphs, tables of terms and formulas are provided.

NASA aerodynamics program

NASA Technical Reports Server (NTRS)

Holmes, Bruce J.; Schairer, Edward; Hicks, Gary; Wander, Stephen; Blankson, Isiaiah; Rose, Raymond; Olson, Lawrence; Unger, George

1990-01-01

Presented here is a comprehensive review of the following aerodynamics elements: computational methods and applications, computational fluid dynamics (CFD) validation, transition and turbulence physics, numerical aerodynamic simulation, drag reduction, test techniques and instrumentation, configuration aerodynamics, aeroacoustics, aerothermodynamics, hypersonics, subsonic transport/commuter aviation, fighter/attack aircraft and rotorcraft.

Incremental Aerodynamic Coefficient Database for the USA2

NASA Technical Reports Server (NTRS)

Richardson, Annie Catherine

2016-01-01

In March through May of 2016, a wind tunnel test was conducted by the Aerosciences Branch (EV33) to visually study the unsteady aerodynamic behavior over multiple transition geometries for the Universal Stage Adapter 2 (USA2) in the MSFC Aerodynamic Research Facility's Trisonic Wind Tunnel (TWT). The purpose of the test was to make a qualitative comparison of the transonic flow field in order to provide a recommended minimum transition radius for manufacturing. Additionally, 6 Degree of Freedom force and moment data for each configuration tested was acquired in order to determine the geometric effects on the longitudinal aerodynamic coefficients (Normal Force, Axial Force, and Pitching Moment). In order to make a quantitative comparison of the aerodynamic effects of the USA2 transition geometry, the aerodynamic coefficient data collected during the test was parsed and incorporated into a database for each USA2 configuration tested. An incremental aerodynamic coefficient database was then developed using the generated databases for each USA2 geometry as a function of Mach number and angle of attack. The final USA2 coefficient increments will be applied to the aerodynamic coefficients of the baseline geometry to adjust the Space Launch System (SLS) integrated launch vehicle force and moment database based on the transition geometry of the USA2.

High-angle-of-attack aerodynamics - Lessons learned

NASA Technical Reports Server (NTRS)

Chambers, J. R.

1986-01-01

Recently, the military and civil technical communities have undertaken numerous studies of the high angle-of-attack aerodynamic characteristics of advanced airplane and missile configurations. The method of approach and the design methodology employed have necessarily been experimental and exploratory in nature, due to the complex nature of separated flows. However, despite the relatively poor definition of many of the key aerodynamic phenomena involved for high-alpha conditions, some generic guidelines for design consideration have been identified. The present paper summarizes some of the more important lessons learned in the area of high angle-of-attack aerodynamics with examples of a number of key concepts and with particular emphasis on high-alpha stability and control characteristics of high performance aircraft. Topics covered in the discussion include the impact of design evolution, forebody flows, control of separated flows, configuration effects, aerodynamic controls, wind-tunnel flight correlation, and recent NASA research activities.

Experimental investigation of hypersonic aerodynamics

NASA Technical Reports Server (NTRS)

Heinemann, K.; Intrieri, Peter F.

1987-01-01

An extensive series of ballistic range tests are currently being conducted at the Ames Research Center. These tests are intended to investigate the hypersonic aerodynamic characteristics of two basic configurations, which are: the blunt-cone Galileo probe which is scheduled to be launched in late 1989 and will enter the atmosphere of Jupiter in 1994, and a generic slender cone configuration to provide experimental aerodynamic data including good flow-field definition which computational aerodynamicists could use to validate their computer codes. Some of the results obtained thus far are presented and work for the near future is discussed.

Autonomous Aerodynamic Control of Micro Air Vehicles

DTIC Science & Technology

2009-10-19

Wind tunnel studies have also begun in which detailed aerodynamic quantification can be mad regarding MAV performance with flexible airframes...research. The design is similar to existing MAVs. The airframe has a conventional aircraft design to allow for easy determination of aerodynamic...exceeded in normal flight by conventional aircraft ; however, it is not uncommon for a MAV to surpass the limits due to its low inertia. While collecting

NACA Conference on Aerodynamic Problems of Transonic Airplane Design

NASA Technical Reports Server (NTRS)

1949-01-01

During the past several years it has been necessary for aeronautical research workers to exert a good portion of their effort in developing the means for conducting research in the high-speed range. The transonic range particularly has presented a very acute problem because of the choking phenomena in wind tunnels at speeds close to the speed of sound. At the same time, the multiplicity of design problems for aircraft introduced by the peculiar flow problems of the transonic speed range has given rise to an enormous demand for detail design data. Substantial progress has been made, however, in developing the required research techniques and in supplying the demand for aerodynamic data required for design purposes. In meeting this demand, it has been necessary to resort to new techniques possessing such novel features that the results obtained have had to be viewed with caution. Furthermore, the kinds of measurements possible with these various techniques are so varied that the correlation of results obtained by different techniques generally becomes an indirect process that can only be accomplished in conjunction with the application of estimates of the extent to which the results of measurements by any given technique are modified by differences that are inherent in the techniques. Thus, in the establishment of the validity and applicability of data obtained by any given technique, direct comparisons between data from different sources are a supplement to but not a substitute for the detailed knowledge required of the characteristics of each technique and fundamental aerodynamic flow phenomena.

An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence

NASA Technical Reports Server (NTRS)

Capece, Vincent R.; Platzer, Max F.

2003-01-01

A major challenge in the design and development of turbomachine airfoils for gas turbine engines is high cycle fatigue failures due to flutter and aerodynamically induced forced vibrations. In order to predict the aeroelastic response of gas turbine airfoils early in the design phase, accurate unsteady aerodynamic models are required. However, accurate predictions of flutter and forced vibration stress at all operating conditions have remained elusive. The overall objectives of this research program are to develop a transition model suitable for unsteady separated flow and quantify the effects of transition on airfoil steady and unsteady aerodynamics for attached and separated flow using this model. Furthermore, the capability of current state-of-the-art unsteady aerodynamic models to predict the oscillating airfoil response of compressor airfoils over a range of realistic reduced frequencies, Mach numbers, and loading levels will be evaluated through correlation with benchmark data. This comprehensive evaluation will assess the assumptions used in unsteady aerodynamic models. The results of this evaluation can be used to direct improvement of current models and the development of future models. The transition modeling effort will also make strides in improving predictions of steady flow performance of fan and compressor blades at off-design conditions. This report summarizes the progress and results obtained in the first year of this program. These include: installation and verification of the operation of the parallel version of TURBO; the grid generation and initiation of steady flow simulations of the NASA/Pratt&Whitney airfoil at a Mach number of 0.5 and chordal incidence angles of 0 and 10 deg.; and the investigation of the prediction of laminar separation bubbles on a NACA 0012 airfoil.

New technology in turbine aerodynamics.

NASA Technical Reports Server (NTRS)

Glassman, A. J.; Moffitt, T. P.

1972-01-01

Cursory review of some recent work that has been done in turbine aerodynamic research. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flowfields. The use of these programs for the design and analysis of axial and radial turbines is discussed.

An Improved Theoretical Aerodynamic Derivatives Computer Program for Sounding Rockets

NASA Technical Reports Server (NTRS)

Barrowman, J. S.; Fan, D. N.; Obosu, C. B.; Vira, N. R.; Yang, R. J.

1979-01-01

The paper outlines a Theoretical Aerodynamic Derivatives (TAD) computer program for computing the aerodynamics of sounding rockets. TAD outputs include normal force, pitching moment and rolling moment coefficient derivatives as well as center-of-pressure locations as a function of the flight Mach number. TAD is applicable to slender finned axisymmetric vehicles at small angles of attack in subsonic and supersonic flows. TAD improvement efforts include extending Mach number regions of applicability, improving accuracy, and replacement of some numerical integration algorithms with closed-form integrations. Key equations used in TAD are summarized and typical TAD outputs are illustrated for a second-stage Tomahawk configuration.

Modeling Aerodynamically Generated Sound of Helicopter Rotors

NASA Technical Reports Server (NTRS)

Brentner, Kenneth S.; Farassat, F.

2002-01-01

A great deal of progress has been made in the modeling of aerodynamically generated sound of rotors over the past decade. Although the modeling effort has focused on helicopter main rotors, the theory is generally valid for a wide range of rotor configurations. The Ffowcs Williams Hawkings (FW-H) equation has been the foundation for much of the development. The monopole and dipole source terms of the FW-H equation account for the thickness and loading noise, respectively. Bladevortex-interaction noise and broadband noise are important types of loading noise, hence much research has been directed toward the accurate modeling of these noise mechanisms. Both subsonic and supersonic quadrupole noise formulations have been developed for the prediction of high-speed impulsive noise. In an effort to eliminate the need to compute the quadrupole contribution, the FW-H equation has also been utilized on permeable surfaces surrounding all physical noise sources. Comparisons of the Kirchhoff formulation for moving surfaces with the FW-H equation have shown that the Kirchhoff formulation for moving surfaces can give erroneous results for aeroacoustic problems. Finally, significant progress has been made incorporating the rotor noise models into full vehicle noise prediction tools.

CFD Simulations of the Supersonic Inflatable Aerodynamic Decelerator (SIAD) Ballistic Range Tests

NASA Technical Reports Server (NTRS)

Brock, Joseph; Stern, Eric; Wilder, Michael

2017-01-01

A series of ballistic range tests were performed on a scaled model of the Supersonic Flight Demonstration Test (SFDT) intended to test the Supersonic Inflatable Aerodynamic Decelerator (SIAD) geometry. The purpose of these experiments were to provide aerodynamic coefficients of the vehicle to aid in mission and vehicle design. The experimental data spans the moderate Mach number range, $3.8-2.0$, with a total angle of attack ($alpha_T$) range, $10o-20o$. These conditions are intended to span the Mach-$alpha$ space for the majority of the SFDT experiment. In an effort to validate the predictive capabilities of Computational Fluid Dynamics (CFD) for free-flight aerodynamic behavior, numerical simulations of the ballistic range experiment are performed using the unstructured finite volume Navier-Stokes solver, US3D. Comparisons to raw vehicle attitude, and post-processed aerodynamic coefficients are made between simulated results and experimental data. The resulting comparisons for both raw model attitude and derived aerodynamic coefficients show good agreement with experimental results. Additionally, near body pressure field values for each trajectory simulated are investigated. Extracted surface and wake pressure data gives further insights into dynamic flow coupling leading to a potential mechanism for dynamic instability.

Enveloping Aerodynamic Decelerator

NASA Technical Reports Server (NTRS)

Nock, Kerry T. (Inventor); Aaron, Kim M. (Inventor); McRonald, Angus D. (Inventor); Gates, Kristin L. (Inventor)

2018-01-01

An inflatable aerodynamic deceleration method and system is provided for use with an atmospheric entry payload. The inflatable aerodynamic decelerator includes an inflatable envelope and an inflatant, wherein the inflatant is configured to fill the inflatable envelope to an inflated state such that the inflatable envelope surrounds the atmospheric entry payload, causing aerodynamic forces to decelerate the atmospheric entry payload.

An integrated study of structures, aerodynamics and controls on the forward swept wing X-29A and the oblique wing research aircraft

NASA Technical Reports Server (NTRS)

Dawson, Kenneth S.; Fortin, Paul E.

1987-01-01

The results of an integrated study of structures, aerodynamics, and controls using the STARS program on two advanced airplane configurations are presented. Results for the X-29A include finite element modeling, free vibration analyses, unsteady aerodynamic calculations, flutter/divergence analyses, and an aeroservoelastic controls analysis. Good correlation is shown between STARS results and various other verified results. The tasks performed on the Oblique Wing Research Aircraft include finite element modeling and free vibration analyses.

Aerodynamic Simulation of the MARINTEK Braceless Semisubmersible Wave Tank Tests

NASA Astrophysics Data System (ADS)

Stewart, Gordon; Muskulus, Michael

2016-09-01

Model scale experiments of floating offshore wind turbines are important for both platform design for the industry as well as numerical model validation for the research community. An important consideration in the wave tank testing of offshore wind turbines are scaling effects, especially the tension between accurate scaling of both hydrodynamic and aerodynamic forces. The recent MARINTEK braceless semisubmersible wave tank experiment utilizes a novel aerodynamic force actuator to decouple the scaling of the aerodynamic forces. This actuator consists of an array of motors that pull on cables to provide aerodynamic forces that are calculated by a blade-element momentum code in real time as the experiment is conducted. This type of system has the advantage of supplying realistically scaled aerodynamic forces that include dynamic forces from platform motion, but does not provide the insights into the accuracy of the aerodynamic models that an actual model-scale rotor could provide. The modeling of this system presents an interesting challenge, as there are two ways to simulate the aerodynamics; either by using the turbulent wind fields as inputs to the aerodynamic model of the design code, or by surpassing the aerodynamic model and using the forces applied to the experimental turbine as direct inputs to the simulation. This paper investigates the best practices of modeling this type of novel aerodynamic actuator using a modified wind turbine simulation tool, and demonstrates that bypassing the dynamic aerodynamics solver of design codes can lead to erroneous results.

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

Unstructured mesh algorithms for aerodynamic calculations

NASA Technical Reports Server (NTRS)

Mavriplis, D. J.

1992-01-01

The use of unstructured mesh techniques for solving complex aerodynamic flows is discussed. The principle advantages of unstructured mesh strategies, as they relate to complex geometries, adaptive meshing capabilities, and parallel processing are emphasized. The various aspects required for the efficient and accurate solution of aerodynamic flows are addressed. These include mesh generation, mesh adaptivity, solution algorithms, convergence acceleration, and turbulence modeling. Computations of viscous turbulent two-dimensional flows and inviscid three-dimensional flows about complex configurations are demonstrated. Remaining obstacles and directions for future research are also outlined.

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.

Tactical missile aerodynamics

NASA Technical Reports Server (NTRS)

Hemsch, Michael J. (Editor); Nielsen, Jack N. (Editor)

1986-01-01

The present conference on tactical missile aerodynamics discusses autopilot-related aerodynamic design considerations, flow visualization methods' role in the study of high angle-of-attack aerodynamics, low aspect ratio wing behavior at high angle-of-attack, supersonic airbreathing propulsion system inlet design, missile bodies with noncircular cross section and bank-to-turn maneuvering capabilities, 'waverider' supersonic cruise missile concepts and design methods, asymmetric vortex sheding phenomena from bodies-of-revolution, and swept shock wave/boundary layer interaction phenomena. Also discussed are the assessment of aerodynamic drag in tactical missiles, the analysis of supersonic missile aerodynamic heating, the 'equivalent angle-of-attack' concept for engineering analysis, the vortex cloud model for body vortex shedding and tracking, paneling methods with vorticity effects and corrections for nonlinear compressibility, the application of supersonic full potential method to missile bodies, Euler space marching methods for missiles, three-dimensional missile boundary layers, and an analysis of exhaust plumes and their interaction with missile airframes.

The influence of distance between vehicles in platoon on aerodynamic parameters

NASA Astrophysics Data System (ADS)

Gnatowska, Renata; Sosnowski, Marcin

2018-06-01

The paper presents the results of experimental and numerical research focused on the reduction of fuel consumption of vehicles driving one after another in a so-called platoon arrangement. The aerodynamic parameters and safety issues were analyzed in order to determine the optimal distance between the vehicles in traffic conditions. The experimental research delivered the results concerning the drag and was performed for simplified model of two vehicles positioned in wind tunnel equipped with aerodynamic balance. The additional numerical analysis allowed investigating the pressure and velocity fields as well as other aerodynamics parameters of the test case.

Study of Swept Angle Effects on Grid Fins Aerodynamics Performance

NASA Astrophysics Data System (ADS)

Faza, G. A.; Fadillah, H.; Silitonga, F. Y.; Agoes Moelyadi, Mochamad

2018-04-01

Grid fin is an aerodynamic control surface that usually used on missiles and rockets. In the recent several years many researches have conducted to develop a more efficient grid fins. There are many possibilities of geometric combination could be done to improve aerodynamics characteristic of a grid fin. This paper will only discuss about the aerodynamics characteristics of grid fins compared by another grid fins with different swept angle. The methodology that used to compare the aerodynamics is Computational Fluid Dynamics (CFD). The result of this paper might be used for future studies to answer our former question or as a reference for related studies.

Photogrammetry of a Hypersonic Inflatable Aerodynamic Decelerator

NASA Technical Reports Server (NTRS)

Kushner, Laura Kathryn; Littell, Justin D.; Cassell, Alan M.

2013-01-01

In 2012, two large-scale models of a Hypersonic Inflatable Aerodynamic decelerator were tested in the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. One of the objectives of this test was to measure model deflections under aerodynamic loading that approximated expected flight conditions. The measurements were acquired using stereo photogrammetry. Four pairs of stereo cameras were mounted inside the NFAC test section, each imaging a particular section of the HIAD. The views were then stitched together post-test to create a surface deformation profile. The data from the photogram- metry system will largely be used for comparisons to and refinement of Fluid Structure Interaction models. This paper describes how a commercial photogrammetry system was adapted to make the measurements and presents some preliminary results.

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.

AERODYNAMIC AND BLADING DESIGN OF MULTISTAGE AXIAL FLOW COMPRESSORS

NASA Technical Reports Server (NTRS)

Crouse, J. E.

1994-01-01

The axial-flow compressor is used for aircraft engines because it has distinct configuration and performance advantages over other compressor types. However, good potential performance is not easily obtained. The designer must be able to model the actual flows well enough to adequately predict aerodynamic performance. This computer program has been developed for computing the aerodynamic design of a multistage axial-flow compressor and, if desired, the associated blading geometry input for internal flow analysis. The aerodynamic solution gives velocity diagrams on selected streamlines of revolution at the blade row edges. The program yields aerodynamic and blading design results that can be directly used by flow and mechanical analysis codes. Two such codes are TSONIC, a blade-to-blade channel flow analysis code (COSMIC program LEW-10977), and MERIDL, a more detailed hub-to-shroud flow analysis code (COSMIC program LEW-12966). The aerodynamic and blading design program can reduce the time and effort required to obtain acceptable multistage axial-flow compressor configurations by generating good initial solutions and by being compatible with available analysis codes. The aerodynamic solution assumes steady, axisymmetric flow so that the problem is reduced to solving the two-dimensional flow field in the meridional plane. The streamline curvature method is used for the iterative aerodynamic solution at stations outside of the blade rows. If a blade design is desired, the blade elements are defined and stacked within the aerodynamic solution iteration. The blade element inlet and outlet angles are established by empirical incidence and deviation angles to the relative flow angles of the velocity diagrams. The blade element centerline is composed of two segments tangentially joined at a transition point. The local blade angle variation of each element can be specified as a fourth-degree polynomial function of path distance. Blade element thickness can also be specified

Formulation of aerodynamic prediction techniques for hypersonic configuration design

NASA Technical Reports Server (NTRS)

1979-01-01

An investigation of approximate theoretical techniques for predicting aerodynamic characteristics and surface pressures for relatively slender vehicles at moderate hypersonic speeds was performed. Emphasis was placed on approaches that would be responsive to preliminary configuration design level of effort. Supersonic second order potential theory was examined in detail to meet this objective. Shock layer integral techniques were considered as an alternative means of predicting gross aerodynamic characteristics. Several numerical pilot codes were developed for simple three dimensional geometries to evaluate the capability of the approximate equations of motion considered. Results from the second order computations indicated good agreement with higher order solutions and experimental results for a variety of wing like shapes and values of the hypersonic similarity parameter M delta approaching one.

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.

Post-Stall Aerodynamic Modeling and Gain-Scheduled Control Design

NASA Technical Reports Server (NTRS)

Wu, Fen; Gopalarathnam, Ashok; Kim, Sungwan

2005-01-01

A multidisciplinary research e.ort that combines aerodynamic modeling and gain-scheduled control design for aircraft flight at post-stall conditions is described. The aerodynamic modeling uses a decambering approach for rapid prediction of post-stall aerodynamic characteristics of multiple-wing con.gurations using known section data. The approach is successful in bringing to light multiple solutions at post-stall angles of attack right during the iteration process. The predictions agree fairly well with experimental results from wind tunnel tests. The control research was focused on actuator saturation and .ight transition between low and high angles of attack regions for near- and post-stall aircraft using advanced LPV control techniques. The new control approaches maintain adequate control capability to handle high angle of attack aircraft control with stability and performance guarantee.

Current research activities: Applied and numerical mathematics, fluid mechanics, experiments in transition and turbulence and aerodynamics, and computer science

NASA Technical Reports Server (NTRS)

1992-01-01

Research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, numerical analysis, fluid mechanics including fluid dynamics, acoustics, and combustion, aerodynamics, and computer science during the period 1 Apr. 1992 - 30 Sep. 1992 is summarized.

Aerodynamic Classification of Swept-Wing Ice Accretion

NASA Technical Reports Server (NTRS)

Broeren, Andy; Diebold, Jeff; Bragg, Mike

2013-01-01

The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current state-of-the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice, and spanwise-ridge ice. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

Parameter assessment for virtual Stackelberg game in aerodynamic shape optimization

NASA Astrophysics Data System (ADS)

Wang, Jing; Xie, Fangfang; Zheng, Yao; Zhang, Jifa

2018-05-01

In this paper, parametric studies of virtual Stackelberg game (VSG) are conducted to assess the impact of critical parameters on aerodynamic shape optimization, including design cycle, split of design variables and role assignment. Typical numerical cases, including the inverse design and drag reduction design of airfoil, have been carried out. The numerical results confirm the effectiveness and efficiency of VSG. Furthermore, the most significant parameters are identified, e.g. the increase of design cycle can improve the optimization results but it will also add computational burden. These studies will maximize the productivity of the effort in aerodynamic optimization for more complicated engineering problems, such as the multi-element airfoil and wing-body configurations.

Aerodynamics of magnetic levitation (MAGLEV) trains

NASA Technical Reports Server (NTRS)

Schetz, Joseph A.; Marchman, James F., III

1996-01-01

High-speed (500 kph) trains using magnetic forces for levitation, propulsion and control offer many advantages for the nation and a good opportunity for the aerospace community to apply 'high tech' methods to the domestic sector. One area of many that will need advanced research is the aerodynamics of such MAGLEV (Magnetic Levitation) vehicles. There are important issues with regard to wind tunnel testing and the application of CFD to these devices. This talk will deal with the aerodynamic design of MAGLEV vehicles with emphasis on wind tunnel testing. The moving track facility designed and constructed in the 6 ft. Stability Wind Tunnel at Virginia Tech will be described. Test results for a variety of MAGLEV vehicle configurations will be presented. The last topic to be discussed is a Multi-disciplinary Design approach that is being applied to MAGLEV vehicle configuration design including aerodynamics, structures, manufacturability and life-cycle cost.

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.

Aerodynamics of a linear oscillating cascade

NASA Technical Reports Server (NTRS)

Buffum, Daniel H.; Fleeter, Sanford

1990-01-01

The steady and unsteady aerodynamics of a linear oscillating cascade are investigated using experimental and computational methods. Experiments are performed to quantify the torsion mode oscillating cascade aerodynamics of the NASA Lewis Transonic Oscillating Cascade for subsonic inlet flowfields using two methods: simultaneous oscillation of all the cascaded airfoils at various values of interblade phase angle, and the unsteady aerodynamic influence coefficient technique. Analysis of these data and correlation with classical linearized unsteady aerodynamic analysis predictions indicate that the wind tunnel walls enclosing the cascade have, in some cases, a detrimental effect on the cascade unsteady aerodynamics. An Euler code for oscillating cascade aerodynamics is modified to incorporate improved upstream and downstream boundary conditions and also the unsteady aerodynamic influence coefficient technique. The new boundary conditions are shown to improve the unsteady aerodynamic influence coefficient technique. The new boundary conditions are shown to improve the unsteady aerodynamic predictions of the code, and the computational unsteady aerodynamic influence coefficient technique is shown to be a viable alternative for calculation of oscillating cascade aerodynamics.

Determination of aerodynamic sensitivity coefficients based on the three-dimensional full potential equation

NASA Technical Reports Server (NTRS)

Elbanna, Hesham M.; Carlson, Leland A.

1992-01-01

The quasi-analytical approach is applied to the three-dimensional full potential equation to compute wing aerodynamic sensitivity coefficients in the transonic regime. Symbolic manipulation is used to reduce the effort associated with obtaining the sensitivity equations, and the large sensitivity system is solved using 'state of the art' routines. Results are compared to those obtained by the direct finite difference approach and both methods are evaluated to determine their computational accuracy and efficiency. The quasi-analytical approach is shown to be accurate and efficient for large aerodynamic systems.

Application of computational aerodynamics methods to the design and analysis of transport aircraft

NASA Technical Reports Server (NTRS)

Da Costa, A. L.

1978-01-01

The application and validation of several computational aerodynamic methods in the design and analysis of transport aircraft is established. An assessment is made concerning more recently developed methods that solve three-dimensional transonic flow and boundary layers on wings. Capabilities of subsonic aerodynamic methods are demonstrated by several design and analysis efforts. Among the examples cited are the B747 Space Shuttle Carrier Aircraft analysis, nacelle integration for transport aircraft, and winglet optimization. The accuracy and applicability of a new three-dimensional viscous transonic method is demonstrated by comparison of computed results to experimental data

Aerodynamic design and optimization in one shot

NASA Technical Reports Server (NTRS)

Ta'asan, Shlomo; Kuruvila, G.; Salas, M. D.

1992-01-01

This paper describes an efficient numerical approach for the design and optimization of aerodynamic bodies. As in classical optimal control methods, the present approach introduces a cost function and a costate variable (Lagrange multiplier) in order to achieve a minimum. High efficiency is achieved by using a multigrid technique to solve for all the unknowns simultaneously, but restricting work on a design variable only to grids on which their changes produce nonsmooth perturbations. Thus, the effort required to evaluate design variables that have nonlocal effects on the solution is confined to the coarse grids. However, if a variable has a nonsmooth local effect on the solution in some neighborhood, it is relaxed in that neighborhood on finer grids. The cost of solving the optimal control problem is shown to be approximately two to three times the cost of the equivalent analysis problem. Examples are presented to illustrate the application of the method to aerodynamic design and constraint optimization.

Studies of aerodynamic technology for VSTOL fighter/attack aircraft

NASA Technical Reports Server (NTRS)

Nelms, W. P.

1978-01-01

The paper summarizes several studies to develop aerodynamic technology for high performance VSTOL aircraft anticipated after 1990. A contracted study jointly sponsored by NASA-Ames and David Taylor Naval Ship Research and Development Center is emphasized. Four contractors analyzed two vertical-attitude and three horizontal-attitude takeoff and landing concepts with gross weights ranging from about 10433 kg (23,000 lb) to 17236 kg (38,000 lb). The aircraft have supersonic capability, high maneuver performance (sustained load factor 6.2 at Mach 0.6, 3048 m (10,000 ft)) and a 4536 kg (10,000-lb) STO overload capability. The contractors have estimated the aerodynamics and identified aerodynamic uncertainties associated with their concept. Example uncertainties relate to propulsion-induced flows, canard-wing interactions, and top inlets. Wind-tunnel research programs were proposed to investigate these uncertainties.

The influence of wing, fuselage and tail design on rotational flow aerodynamics data obtained beyond maximum lift with general aviation configurations

NASA Technical Reports Server (NTRS)

Bihrle, W., Jr.; Bowman, J. S., Jr.

1980-01-01

The NASA Langley Research Center has initiated a broad general aviation stall/spin research program. A rotary balance system was developed to support this effort. Located in the Langley spin tunnel, this system makes it possible to identify an airplane's aerodynamic characteristics in a rotational flow environment, and thereby permits prediction of spins. This paper presents a brief description of the experimental set-up, testing technique, five model programs conducted to date, and an overview of the rotary balance results and their correlation with spin tunnel free-spinning model results. It is shown, for example, that there is a large, nonlinear dependency of the aerodynamic moments on rotational rate and that these moments are pronouncedly configuration-dependent. Fuselage shape, horizontal tail and, in some instances, wing location are shown to appreciably influence the yawing moment characteristics above an angle of attack of 45 deg.

Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Technology Development Overview

NASA Technical Reports Server (NTRS)

Hughes, Stephen J.; Cheatwood, F. McNeil; Calomino, Anthony M.; Wright, Henry S.

2013-01-01

The successful flight of the Inflatable Reentry Vehicle Experiment (IRVE)-3 has further demonstrated the potential value of Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. This technology development effort is funded by NASA's Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP). This paper provides an overview of a multi-year HIAD technology development effort, detailing the projects completed to date and the additional testing planned for the future. The effort was divided into three areas: Flexible Systems Development (FSD), Mission Advanced Entry Concepts (AEC), and Flight Validation. FSD consists of a Flexible Thermal Protection Systems (FTPS) element, which is investigating high temperature materials, coatings, and additives for use in the bladder, insulator, and heat shield layers; and an Inflatable Structures (IS) element which includes manufacture and testing (laboratory and wind tunnel) of inflatable structures and their associated structural elements. AEC consists of the Mission Applications element developing concepts (including payload interfaces) for missions at multiple destinations for the purpose of demonstrating the benefits and need for the HIAD technology as well as the Next Generation Subsystems element. Ground test development has been pursued in parallel with the Flight Validation IRVE-3 flight test. A larger scale (6m diameter) HIAD inflatable structure was constructed and aerodynamically tested in the National Full-scale Aerodynamics Complex (NFAC) 40ft by 80ft test section along with a duplicate of the IRVE-3 3m article. Both the 6m and 3m articles were tested with instrumented aerodynamic covers which incorporated an array of pressure taps to capture surface pressure distribution to validate Computational Fluid Dynamics (CFD) model predictions of surface pressure distribution. The 3m article also had a duplicate IRVE-3 Thermal Protection System (TPS) to test in addition to testing with the

Structural/aerodynamic Blade Analyzer (SAB) User's Guide, Version 1.0

NASA Technical Reports Server (NTRS)

Morel, M. R.

1994-01-01

The structural/aerodynamic blade (SAB) analyzer provides an automated tool for the static-deflection analysis of turbomachinery blades with aerodynamic and rotational loads. A structural code calculates a deflected blade shape using aerodynamic loads input. An aerodynamic solver computes aerodynamic loads using deflected blade shape input. The two programs are iterated automatically until deflections converge. Currently, SAB version 1.0 is interfaced with MSC/NASTRAN to perform the structural analysis and PROP3D to perform the aerodynamic analysis. This document serves as a guide for the operation of the SAB system with specific emphasis on its use at NASA Lewis Research Center (LeRC). This guide consists of six chapters: an introduction which gives a summary of SAB; SAB's methodology, component files, links, and interfaces; input/output file structure; setup and execution of the SAB files on the Cray computers; hints and tips to advise the user; and an example problem demonstrating the SAB process. In addition, four appendices are presented to define the different computer programs used within the SAB analyzer and describe the required input decks.

Group-effort Applied Research: Expanding Opportunities for Undergraduate Research through Original, Class-Based Research Projects

ERIC Educational Resources Information Center

Moore, Sean D.; Teter, Ken

2014-01-01

Undergraduate research clearly enriches the educational development of participating students, but these experiences are limited by the inherent inefficiency of the standard one student-one mentor model for undergraduate research. Group-effort applied research (GEAR) was developed as a strategy to provide substantial numbers of undergraduates with…

Orion Crew Module Aerodynamic Testing

NASA Technical Reports Server (NTRS)

Murphy, Kelly J.; Bibb, Karen L.; Brauckmann, Gregory J.; Rhode, Matthew N.; Owens, Bruce; Chan, David T.; Walker, Eric L.; Bell, James H.; Wilson, Thomas M.

2011-01-01

The Apollo-derived Orion Crew Exploration Vehicle (CEV), part of NASA s now-cancelled Constellation Program, has become the reference design for the new Multi-Purpose Crew Vehicle (MPCV). The MPCV will serve as the exploration vehicle for all near-term human space missions. A strategic wind-tunnel test program has been executed at numerous facilities throughout the country to support several phases of aerodynamic database development for the Orion spacecraft. This paper presents a summary of the experimental static aerodynamic data collected to-date for the Orion Crew Module (CM) capsule. The test program described herein involved personnel and resources from NASA Langley Research Center, NASA Ames Research Center, NASA Johnson Space Flight Center, Arnold Engineering and Development Center, Lockheed Martin Space Sciences, and Orbital Sciences. Data has been compiled from eight different wind tunnel tests in the CEV Aerosciences Program. Comparisons are made as appropriate to highlight effects of angle of attack, Mach number, Reynolds number, and model support system effects.

Economical Unsteady High-Fidelity Aerodynamics for Structural Optimization with a Flutter Constraint

NASA Technical Reports Server (NTRS)

Bartels, Robert E.; Stanford, Bret K.

2017-01-01

Structural optimization with a flutter constraint for a vehicle designed to fly in the transonic regime is a particularly difficult task. In this speed range, the flutter boundary is very sensitive to aerodynamic nonlinearities, typically requiring high-fidelity Navier-Stokes simulations. However, the repeated application of unsteady computational fluid dynamics to guide an aeroelastic optimization process is very computationally expensive. This expense has motivated the development of methods that incorporate aspects of the aerodynamic nonlinearity, classical tools of flutter analysis, and more recent methods of optimization. While it is possible to use doublet lattice method aerodynamics, this paper focuses on the use of an unsteady high-fidelity aerodynamic reduced order model combined with successive transformations that allows for an economical way of utilizing high-fidelity aerodynamics in the optimization process. This approach is applied to the common research model wing structural design. As might be expected, the high-fidelity aerodynamics produces a heavier wing than that optimized with doublet lattice aerodynamics. It is found that the optimized lower skin of the wing using high-fidelity aerodynamics differs significantly from that using doublet lattice aerodynamics.

Bat flight: aerodynamics, kinematics and flight morphology.

PubMed

Hedenström, Anders; Johansson, L Christoffer

2015-03-01

Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace. © 2015. Published by The Company of Biologists Ltd.

Aero-Structural Assessment of an Inflatable Aerodynamic Decelerator

NASA Technical Reports Server (NTRS)

Sheta, Essam F.; Venugopalan, Vinod; Tan, X. G.; Liever, Peter A.; Habchi, Sami D.

2010-01-01

NASA is conducting an Entry, Descent and Landing Systems Analysis (EDL-SA) Study to determine the key technology development projects that should be undertaken for enabling the landing of large payloads on Mars for both human and robotic missions. Inflatable Aerodynamic Decelerators (IADs) are one of the candidate technologies. A variety of EDL architectures are under consideration. The current effort is conducted for development and simulations of computational framework for inflatable structures.

Comparison of Theodorsen's Unsteady Aerodynamic Forces with Doublet Lattice Generalized Aerodynamic Forces

NASA Technical Reports Server (NTRS)

Perry, Boyd, III

2017-01-01

This paper identifies the unsteady aerodynamic forces and moments for a typical section contained in the NACA Report No. 496, "General Theory of Aerodynamic Instability and the Mechanism of Flutter," by Theodore Theodorsen. These quantities are named Theodorsen's aerodynamic forces (TAFs). The TAFs are compared to the generalized aerodynamic forces (GAFs) for a very high aspect ratio wing (AR = 20) at zero Mach number computed by the doublet lattice method. Agreement between TAFs and GAFs is very-good-to-excellent. The paper also reveals that simple proportionality relationships that are known to exist between the real parts of some GAFs and the imaginary parts of others also hold for the real and imaginary parts of the corresponding TAFs.

48 CFR 35.009 - Subcontracting research and development effort.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING RESEARCH AND DEVELOPMENT CONTRACTING 35.009 Subcontracting research and development effort. Since the selection of R&D contractors is substantially based on... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Subcontracting research...

Status report on the Aeronautical Research Institute of Sweden version of the missile aerodynamics program LARV, for calculation of static aerodynamic properties and longitudinal aerodynamic damping derivatives. Part 1: Theory

NASA Astrophysics Data System (ADS)

Weibust, E.

Improvements to a missile aerodynamics program which enable it to (a) calculate aerodynamic coefficients as input for a flight mechanics model, (b) check manufacturers' data or estimate performance from photographs, (c) reduce wind tunnel testing, and (d) aid optimization studies, are discussed. Slender body theory is used for longitudinal damping derivatives prediction. Program predictions were compared to known values. Greater accuracy is required in the estimation of drag due to excrescences on actual missile configurations, the influence of a burning motor, and nonlinear effects in the stall region. Prediction of pressure centers on wings and on bodies in presence of wings must be improved.

Missile Aerodynamics

DTIC Science & Technology

1979-02-01

aimed to emphasize these differences in the aerodynamic design features of both guided and unguided weapons. In addition to treating the component parts...the subject. Lectures generally started with a review of fundamentals and paid particular attention to practical methods of estimation and design and...George G Brebner Aerodynamics Department Royal Aircraft Establishment Farnborough, Hants, GU14 6TD, UK SUMMARY The differences in design objectives and

Case Studies in Describing Scientific Research Efforts as Linked Data

NASA Astrophysics Data System (ADS)

Gandara, A.; Villanueva-Rosales, N.; Gates, A.

2013-12-01

The Web is growing with numerous scientific resources, prompting increased efforts in information management to consider integration and exchange of scientific resources. Scientists have many options to share scientific resources on the Web; however, existing options provide limited support to scientists in annotating and relating research resources resulting from a scientific research effort. Moreover, there is no systematic approach to documenting scientific research and sharing it on the Web. This research proposes the Collect-Annotate-Refine-Publish (CARP) Methodology as an approach for guiding documentation of scientific research on the Semantic Web as scientific collections. Scientific collections are structured descriptions about scientific research that make scientific results accessible based on context. In addition, scientific collections enhance the Linked Data data space and can be queried by machines. Three case studies were conducted on research efforts at the Cyber-ShARE Research Center of Excellence in order to assess the effectiveness of the methodology to create scientific collections. The case studies exposed the challenges and benefits of leveraging the Semantic Web and Linked Data data space to facilitate access, integration and processing of Web-accessible scientific resources and research documentation. As such, we present the case study findings and lessons learned in documenting scientific research using CARP.

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.

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.

NASA's Role in Aeronautics: A Workshop. Volume 6: Aeronautical research

NASA Technical Reports Server (NTRS)

1981-01-01

While each aspect of its aeronautical technology program is important to the current preeminence of the United States in aeronautics, the most essential contributions of NASA derive from its research. Successes and challenges in NASA's efforts to improve civil and military aviation are discussed for the following areas: turbulence, noise, supercritical aerodynamics, computational aerodynamics, fuels, high temperature materials, composite materials, single crystal components, powder metallurgy, and flight controls. Spin offs to engineering and other sciences explored include NASTRAN, lubricants, and composites.

V/STOL Aerodynamics

DTIC Science & Technology

1974-10-01

jet exhaust, m (ft) Ro radius of engine exhaust, m (ft) 1. INTRODUCTION free deg S wing area, m2 (ft2) t time, see T Thrust, N (lb) u...dimensional potential flow method to lift prediction for a wing with internally blown flaps is described. INTRODUCTION The objectives of this paper are...twofold. The first is to provide an introduction to this session on research into the aerodynamics of powered high lift systems. This will be

NASA Agricultural Aircraft Research Program in the Langley Vortex Research Facility and the Langley Full Scale Wind Tunnel

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Aerodynamics Via Acoustics: Application of Acoustic Formulas for Aerodynamic Calculations

NASA Technical Reports Server (NTRS)

Farassat, F.; Myers, M. K.

1986-01-01

Prediction of aerodynamic loads on bodies in arbitrary motion is considered from an acoustic point of view, i.e., in a frame of reference fixed in the undisturbed medium. An inhomogeneous wave equation which governs the disturbance pressure is constructed and solved formally using generalized function theory. When the observer is located on the moving body surface there results a singular linear integral equation for surface pressure. Two different methods for obtaining such equations are discussed. Both steady and unsteady aerodynamic calculations are considered. Two examples are presented, the more important being an application to propeller aerodynamics. Of particular interest for numerical applications is the analytical behavior of the kernel functions in the various integral equations.

Military aircraft and missile technology at the Langley Research Center: A selected bibliography

NASA Technical Reports Server (NTRS)

Maddalon, D. V.

1980-01-01

A compilation of reference material is presented on the Langley Research Center's efforts in developing advanced military aircraft and missile technology over the past twenty years. Reference material includes research made in aerodynamics, performance, stability, control, stall-spin, propulsion integration, flutter, materials, and structures.

Aerodynamic Classification of Swept-Wing Ice Accretion

NASA Technical Reports Server (NTRS)

Diebold, Jeff M.; Broeren, Andy P.; Bragg, Michael B.

2013-01-01

The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current stateof- the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice and spanwise-ridge ice. In the case of horn ice it is shown that a further subclassification of "nominally 3D" or "highly 3D" horn ice may be necessary. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

Aerodynamic Classification of Swept-Wing Ice Accretion

NASA Technical Reports Server (NTRS)

Diebold, Jeff M.; Broeren, Andy P.; Bragg, Michael B.

2013-01-01

The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current state-of-the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice and spanwise-ridge ice. In the case of horn ice it is shown that a further subclassification of nominally 3D or highly 3D horn ice may be necessary. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

Innovation in Aerodynamic Design Features of Soviet Missiles

NASA Technical Reports Server (NTRS)

Spearman, M. Leroy

2006-01-01

Wind tunnel investigations of some tactical and strategic missile systems developed by the former Soviet Union have been included in the basic missile research programs of the NACA/NASA. Studies of the Soviet missiles sometimes revealed innovative design features that resulted in unusual or unexpected aerodynamic characteristics. In some cases these characteristics have been such that the measured performance of the missile exceeds what might have been predicted. In other cases some unusual design features have been found that would alleviate what might otherwise have been a serious aerodynamic problem. In some designs, what has appeared to be a lack of refinement has proven to be a matter of expediency. It is a purpose of this paper to describe some examples of unusual design features of some Soviet missiles and to illustrate the effectiveness of the design features on the aerodynamic behavior of the missile. The paper draws on the experience of the author who for over 60 years was involved in the aerodynamic wind tunnel testing of aircraft and missiles with the NACA/NASA.

Development of the X-33 Aerodynamic Uncertainty Model

NASA Technical Reports Server (NTRS)

Cobleigh, Brent R.

1998-01-01

An aerodynamic uncertainty model for the X-33 single-stage-to-orbit demonstrator aircraft has been developed at NASA Dryden Flight Research Center. The model is based on comparisons of historical flight test estimates to preflight wind-tunnel and analysis code predictions of vehicle aerodynamics documented during six lifting-body aircraft and the Space Shuttle Orbiter flight programs. The lifting-body and Orbiter data were used to define an appropriate uncertainty magnitude in the subsonic and supersonic flight regions, and the Orbiter data were used to extend the database to hypersonic Mach numbers. The uncertainty data consist of increments or percentage variations in the important aerodynamic coefficients and derivatives as a function of Mach number along a nominal trajectory. The uncertainty models will be used to perform linear analysis of the X-33 flight control system and Monte Carlo mission simulation studies. Because the X-33 aerodynamic uncertainty model was developed exclusively using historical data rather than X-33 specific characteristics, the model may be useful for other lifting-body studies.

Aerodynamics and Ecomorphology of Flexible Feathers and Morphing Bird Wings

NASA Astrophysics Data System (ADS)

Klaassen van Oorschot, Brett

shape affected performance during flapping but not gliding flight. Extended wings outperformed swept wings by about a third in flapping flight. This finding contrasts previous work that showed wing shape didn't affect performance in flapping flight (Usherwood and Ellington, 2002a, 2002b). This work provided key insights that inspired the second and third chapters of my dissertation. The second chapter examines the significance of wing tip slots across 135 avian species, ranging from small passerines to large seabirds. This research was completed with the help of an undergraduate international researcher, Ho Kwan Tang, and is currently in press at the Journal of Morphology (Klaassen van Oorschot, in press). These slots are caused by asymmetric emarginations missing from the leading and trailing edge of the primary feathers. We used a novel metric of primary feather emargination that allowed us to show that wing tip slots are nearly ubiquitous across the avian clade. We also showed that emargination is segregated according to habitat and behavioral metrics like flight style. Finally, we showed that emargination scaled with mass. These findings illustrated that wing tip slots may be an adaptation for efficacy during vertical takeoff rather than efficiency during gliding flight. In the third chapter, I sought to better understand the function of these slotted primary feathers. In an effort to bridge biology and aeronautics, I collaborated with Richard Choroszucha, an aeronautical engineer from the University of Michigan, on this work. These feathers deflect under aerodynamic load, and it has been hypothesized that they reduce induced drag during gliding flight (Tucker, 1993, 1995). We exposed individual primary feathers to different speeds in the wind tunnel and measured deflection such as bend, twist, and sweep. We found that feather deflection reoriented force, resulting in increased lateral stability and delayed stall characteristics compared to a rigid airfoil. These

Distributed Aerodynamic Sensing and Processing Toolbox

NASA Technical Reports Server (NTRS)

Brenner, Martin; Jutte, Christine; Mangalam, Arun

2011-01-01

A Distributed Aerodynamic Sensing and Processing (DASP) toolbox was designed and fabricated for flight test applications with an Aerostructures Test Wing (ATW) mounted under the fuselage of an F-15B on the Flight Test Fixture (FTF). DASP monitors and processes the aerodynamics with the structural dynamics using nonintrusive, surface-mounted, hot-film sensing. This aerodynamic measurement tool benefits programs devoted to static/dynamic load alleviation, body freedom flutter suppression, buffet control, improvement of aerodynamic efficiency through cruise control, supersonic wave drag reduction through shock control, etc. This DASP toolbox measures local and global unsteady aerodynamic load distribution with distributed sensing. It determines correlation between aerodynamic observables (aero forces) and structural dynamics, and allows control authority increase through aeroelastic shaping and active flow control. It offers improvements in flutter suppression and, in particular, body freedom flutter suppression, as well as aerodynamic performance of wings for increased range/endurance of manned/ unmanned flight vehicles. Other improvements include inlet performance with closed-loop active flow control, and development and validation of advanced analytical and computational tools for unsteady aerodynamics.

Determination of aerodynamic sensitivity coefficients for wings in transonic flow

NASA Technical Reports Server (NTRS)

Carlson, Leland A.; El-Banna, Hesham M.

1992-01-01

The quasianalytical approach is applied to the 3-D full potential equation to compute wing aerodynamic sensitivity coefficients in the transonic regime. Symbolic manipulation is used to reduce the effort associated with obtaining the sensitivity equations, and the large sensitivity system is solved using 'state of the art' routines. The quasianalytical approach is believed to be reasonably accurate and computationally efficient for 3-D problems.

Low Speed Rot or/Fuselage Interactional Aerodynamics

NASA Technical Reports Server (NTRS)

Barnwell, Richard W.; Prichard, Devon S.

2003-01-01

This report presents work performed under a Cooperative Research Agreement between Virginia Tech and the NASA Langley Research Center. The work involved development of computational techniques for modeling helicopter rotor/airframe aerodynamic interaction. A brief overview of the problem is presented, the modeling techniques are described, and selected example calculations are briefly discussed.

Aerodynamic Analyses Requiring Advanced Computers, part 2

NASA Technical Reports Server (NTRS)

1975-01-01

Papers given at the conference present the results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include two-dimensional configurations, three-dimensional configurations, transonic aircraft, and the space shuttle.

Quasi-Steady Simulations for the Efficient Generation of Static Aerodynamic Coefficients at Subsonic Velocity

DTIC Science & Technology

2016-09-01

ARL-TR-7790 ● SEP 2016 US Army Research Laboratory Quasi -Steady Simulations for the Efficient Generation of Static Aerodynamic... Quasi -Steady Simulations for the Efficient Generation of Static Aerodynamic Coefficients at Subsonic Velocity by Sidra I Silton Weapons and...To) December 2014–April 2015 4. TITLE AND SUBTITLE Quasi -Steady Simulations for the Efficient Generation of Static Aerodynamic Coefficients at

NWTC Aerodynamics Studies Improve Energy Capture and Lower Costs of Wind-Generated Electricity

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

2015-08-01

Researchers at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) have expanded wind turbine aerodynamic research from blade and rotor aerodynamics to wind plant and atmospheric inflow effects. The energy capture from wind plants is dependent on all of these aerodynamic interactions. Research at the NWTC is crucial to understanding how wind turbines function in large, multiple-row wind plants. These conditions impact the cumulative fatigue damage of turbine structural components that ultimately effect the useful lifetime of wind turbines. This work also is essential for understanding and maximizing turbine and wind plant energy production. Bothmore » turbine lifetime and wind plant energy production are key determinants of the cost of wind-generated electricity.« less

Systematic Dissemination of Research and Development Program Improvement Efforts.

ERIC Educational Resources Information Center

Sanders, Carol S.

A systematic approach to disseminaton of vocational education research and development program improvement efforts is comprehensive, effective, and efficient. Systematic dissemination is a prerequisite link to assessing impact of research and development--for program improvement to occur, successful dissemination is crucial. A systematic approach…

Aerodynamic Analyses Requiring Advanced Computers, Part 1

NASA Technical Reports Server (NTRS)

1975-01-01

Papers are presented which deal with results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include: viscous flows, boundary layer equations, turbulence modeling and Navier-Stokes equations, and internal flows.

Potential impacts of advanced aerodynamic technology on air transportation system productivity

NASA Technical Reports Server (NTRS)

Bushnell, Dennis M. (Editor)

1994-01-01

Summaries of a workshop held at NASA Langley Research Center in 1993 to explore the application of advanced aerodynamics to airport productivity improvement are discussed. Sessions included discussions of terminal area productivity problems and advanced aerodynamic technologies for enhanced high lift and reduced noise, emissions, and wake vortex hazard with emphasis upon advanced aircraft configurations and multidisciplinary solution options.

Numerical Aerodynamic Simulation

NASA Technical Reports Server (NTRS)

1989-01-01

An overview of historical and current numerical aerodynamic simulation (NAS) is given. The capabilities and goals of the Numerical Aerodynamic Simulation Facility are outlined. Emphasis is given to numerical flow visualization and its applications to structural analysis of aircraft and spacecraft bodies. The uses of NAS in computational chemistry, engine design, and galactic evolution are mentioned.

Aerodynamic mathematical modeling - basic concepts

NASA Technical Reports Server (NTRS)

Tobak, M.; Schiff, L. B.

1981-01-01

The mathematical modeling of the aerodynamic response of an aircraft to arbitrary maneuvers is reviewed. Bryan's original formulation, linear aerodynamic indicial functions, and superposition are considered. These concepts are extended into the nonlinear regime. The nonlinear generalization yields a form for the aerodynamic response that can be built up from the responses to a limited number of well defined characteristic motions, reproducible in principle either in wind tunnel experiments or flow field computations. A further generalization leads to a form accommodating the discontinuous and double valued behavior characteristics of hysteresis in the steady state aerodynamic response.

Wind Tunnel Testing on Crosswind Aerodynamic Forces Acting on Railway Vehicles

NASA Astrophysics Data System (ADS)

Kwon, Hyeok-Bin; Nam, Seong-Won; You, Won-Hee

This study is devoted to measure the aerodynamic forces acting on two railway trains, one of which is a high-speed train at 300km/h maximum operation speed, and the other is a conventional train at the operating speed 100km/h. The three-dimensional train shapes have been modeled as detailed as possible including the inter-car, the upper cavity for pantograph, and the bogie systems. The aerodynamic forces on each vehicle of the trains have been measured in the subsonic wind tunnel with 4m×3m test section of Korea Aerospace Research Institute at Daejeon, Korea. The aerodynamic forces and moments of the train models have been plotted for various yaw angles and the characteristics of the aerodynamic coefficients has been discussed relating to the experimental conditions.

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.

Missile Aerodynamics for Ascent and Re-entry

NASA Technical Reports Server (NTRS)

Watts, Gaines L.; McCarter, James W.

2012-01-01

Aerodynamic force and moment equations are developed for 6-DOF missile simulations of both the ascent phase of flight and a tumbling re-entry. The missile coordinate frame (M frame) and a frame parallel to the M frame were used for formulating the aerodynamic equations. The missile configuration chosen as an example is a cylinder with fixed fins and a nose cone. The equations include both the static aerodynamic coefficients and the aerodynamic damping derivatives. The inclusion of aerodynamic damping is essential for simulating a tumbling re-entry. Appended information provides insight into aerodynamic damping.

Tobacco industry efforts to undermine policy-relevant research.

PubMed

Landman, Anne; Glantz, Stanton A

2009-01-01

The tobacco industry, working through third parties to prevent policy-relevant research that adversely affected it between 1988 and 1998, used coordinated, well-funded strategies in repeated attempts to silence tobacco researcher Stanton A. Glantz. Tactics included advertising, litigation, and attempts to have the US Congress cut off the researcher's National Cancer Institute funding. Efforts like these can influence the policymaking process by silencing opposing voices and discouraging other scientists from doing work that may expose them to tobacco industry attacks. The support of highly credible public health organizations and of researchers' employers is crucial to the continued advancement of public health.

The present status and the future of missile aerodynamics

NASA Technical Reports Server (NTRS)

Nielsen, Jack N.

1989-01-01

Recent developments in the state of the art in missile aerodynamics are reviewed. Among the subjects covered are: (1) Tri-service/NASA data base, (2) wing-body interference, (3) nonlinear controls, (4) hypersonic transition, (5) vortex interference, (6) airbreathers, supersonic inlets, (7) store separation problems, (8) correlation of missile data, (9) CFD codes for complete configurations, (10) engineering prediction methods, and (11) future configurations. Suggestions are made for future research and development to advance the state of the art of missile aerodynamics.

The present status and the future of missile aerodynamics

NASA Technical Reports Server (NTRS)

Nielsen, Jack N.

1988-01-01

Some recent developments in the state of the art in missile aerodynamics are reviewed. Among the subjects covered are: (1) tri-service/NASA data base, (2) wing-body interference, (3) nonlinear controls, (4) hypersonic transition, (5) vortex interference, (6) airbreathers, supersonic inlets, (7) store separation problems, (8) correlation of missile data, (9) CFD codes for complete configurations, (10) engineering prediction methods, and (11) future configurations. Suggestions are made for future research and development to advance the state of the art of missile aerodynamics.

Integration of CFD and Experimental Results at VKI in Low-Speed Aerodynamic Design

DTIC Science & Technology

2007-06-01

erosion in wind tunnel behind the building Today, almost all modern Antartic stations have undergone aerodynamic studies at different stages of design...2] J. Sanz Rodrigo, C. Gorle, J. van Beeck, P. Planquart: Aerodynamic Design of the Princess Elizabeth Antartic Research Station, 17th

Preliminary aerodynamic design considerations for advanced laminar flow aircraft configurations

NASA Technical Reports Server (NTRS)

Johnson, Joseph L., Jr.; Yip, Long P.; Jordan, Frank L., Jr.

1986-01-01

Modern composite manufacturing methods have provided the opportunity for smooth surfaces that can sustain large regions of natural laminar flow (NLF) boundary layer behavior and have stimulated interest in developing advanced NLF airfoils and improved aircraft designs. Some of the preliminary results obtained in exploratory research investigations on advanced aircraft configurations at the NASA Langley Research Center are discussed. Results of the initial studies have shown that the aerodynamic effects of configuration variables such as canard/wing arrangements, airfoils, and pusher-type and tractor-type propeller installations can be particularly significant at high angles of attack. Flow field interactions between aircraft components were shown to produce undesirable aerodynamic effects on a wing behind a heavily loaded canard, and the use of properly designed wing leading-edge modifications, such as a leading-edge droop, offset the undesirable aerodynamic effects by delaying wing stall and providing increased stall/spin resistance with minimum degradation of laminar flow behavior.

Correlates of Research Effort in Carnivores: Body Size, Range Size and Diet Matter

PubMed Central

Brooke, Zoe M.; Bielby, Jon; Nambiar, Kate; Carbone, Chris

2014-01-01

Given the budgetary restrictions on scientific research and the increasing need to better inform conservation actions, it is important to identify the patterns and causes of biases in research effort. We combine bibliometric information from a literature review of almost 16,500 peer-reviewed publications on a well-known group of 286 species, the Order Carnivora, with global datasets on species' life history and ecological traits to explore patterns in research effort. Our study explores how species' characteristics influenced the degree to which they were studied (measured as the number of publications). We identified a wide variation in intensity of research effort at both Family and Species levels, with some of the least studied being those which may need protection in future. Our findings hint at the complex role of human perspectives in setting research agendas. We found that better-studied species tended to be large-bodied and have a large geographic range whilst omnivory had a negative relationship with research effort. IUCN threat status did not exhibit a strong relationship with research effort which suggests that the conservation needs of individual species are not major drivers of research interest. This work is the first to use a combination of bibliometric analysis and biological data to quantify and interpret gaps in research knowledge across an entire Order. Our results could be combined with other resources, such as Biodiversity Action Plans, to prioritise and co-ordinate future research effort, whilst our methods can be applied across many scientific disciplines to describe knowledge gaps. PMID:24695422

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.

Freight Wing Trailer Aerodynamics Final Technical Report

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

Sean Graham

2007-10-31

Freight Wing Incorporated utilized the opportunity presented by a DOE category two Inventions and Innovations grant to commercialize and improve upon aerodynamic technology for semi-tuck trailers, capable of decreasing heavy vehicle fuel consumption, related environmental damage, and U.S. consumption of foreign oil. Major project goals included the demonstration of aerodynamic trailer technology in trucking fleet operations, and the development and testing of second generation products. A great deal of past scientific research has demonstrated that streamlining box shaped semi-trailers can significantly reduce a truck’s fuel consumption. However, significant design challenges have prevented past concepts from meeting industry needs. Freight Wingmore » utilized a 2003 category one Inventions and Innovations grant to develop practical solutions to trailer aerodynamics. Fairings developed for the front, rear, and bottom of standard semi-trailers together demonstrated a 7% improvement to fuel economy in scientific tests conducted by the Transportation Research Center (TRC). Operational tests with major trucking fleets proved the functionality of the products, which were subsequently brought to market. This category two grant enabled Freight Wing to further develop, test and commercialize its products, resulting in greatly increased understanding and acceptance of aerodynamic trailer technology. Commercialization was stimulated by offering trucking fleets 50% cost sharing on trial implementations of Freight Wing products for testing and evaluation purposes. Over 230 fairings were implemented through the program with 35 trucking fleets including industry leaders such as Wal-Mart, Frito Lay and Whole Foods. The feedback from these testing partnerships was quite positive with product performance exceeding fleet expectations in many cases. Fleet feedback also was also valuable from a product development standpoint and assisted the design of several second generation

A Semantic Web-Based Methodology for Describing Scientific Research Efforts

ERIC Educational Resources Information Center

Gandara, Aida

2013-01-01

Scientists produce research resources that are useful to future research and innovative efforts. In a typical scientific scenario, the results created by a collaborative team often include numerous artifacts, observations and relationships relevant to research findings, such as programs that generate data, parameters that impact outputs, workflows…

The space shuttle launch vehicle aerodynamic verification challenges

NASA Technical Reports Server (NTRS)

Wallace, R. O.; Austin, L. D.; Hondros, J. G.; Surber, T. E.; Gaines, L. M.; Hamilton, J. T.

1985-01-01

The Space Shuttle aerodynamics and performance communities were challenged to verify the Space Shuttle vehicle (SSV) aerodynamics and system performance by flight measurements. Historically, launch vehicle flight test programs which faced these same challenges were unmanned instrumented flights of simple aerodynamically shaped vehicles. However, the manned SSV flight test program made these challenges more complex because of the unique aerodynamic configuration powered by the first man-rated solid rocket boosters (SRB). The analyses of flight data did not verify the aerodynamics or performance preflight predictions of the first flight of the Space Transportation System (STS-1). However, these analyses have defined the SSV aerodynamics and verified system performance. The aerodynamics community also was challenged to understand the discrepancy between the wind tunnel and flight defined aerodynamics. The preflight analysis challenges, the aerodynamic extraction challenges, and the postflight analyses challenges which led to the SSV system performance verification and which will lead to the verification of the operational ascent aerodynamics data base are presented.

An initial investigation into methods of computing transonic aerodynamic sensitivity coefficients

NASA Technical Reports Server (NTRS)

Carlson, Leland A.

1992-01-01

Research conducted during the period from July 1991 through December 1992 is covered. A method based upon the quasi-analytical approach was developed for computing the aerodynamic sensitivity coefficients of three dimensional wings in transonic and subsonic flow. In addition, the method computes for comparison purposes the aerodynamic sensitivity coefficients using the finite difference approach. The accuracy and validity of the methods are currently under investigation.

Research on Aerodynamic Characteristics of Composite powered Unmanned Airship

NASA Astrophysics Data System (ADS)

Chen, Yu; Wang, Yun; Wang, Lu; Ma, Chengyu; Xia, Jun

2017-10-01

The main structure of the composite powered unmanned airship is consists of airbags and four-rotor system, which airbag increases the available lift, and has more advantages in terms of load and flight when compared with the traditional four-rotor. In order to compare the aerodynamic performance of the composite powered unmanned airship and the traditional four-rotor, the SIMPLE algorithm and the RNG k-epsilon model method are be used. The energy consumption of the composite powered unmanned airship is lesser than the traditional four-rotor under the same load and range was found.

Aerodynamic Noise Generated by Shinkansen Cars

NASA Astrophysics Data System (ADS)

KITAGAWA, T.; NAGAKURA, K.

2000-03-01

The noise value (A -weighted sound pressure level, SLOW) generated by Shinkansen trains, now running at 220-300 km/h, should be less than 75 dB(A) at the trackside. Shinkansen noise, such as rolling noise, concrete support structure noise, and aerodynamic noise are generated by various parts of Shinkansen trains. Among these aerodynamic noise is important because it is the major contribution to the noise generated by the coaches running at high speed. In order to reduce the aerodynamic noise, a number of improvements to coaches have been made. As a result, the aerodynamic noise has been reduced, but it still remains significant. In addition, some aerodynamic noise generated from the lower parts of cars remains. In order to investigate the contributions of these noises, a method of analyzing Shinkansen noise has been developed and applied to the measured data of Shinkansen noise at speeds between 120 and 315 km/h. As a result, the following conclusions have been drawn: (1) Aerodynamic noise generated from the upper parts of cars was reduced considerably by smoothing car surfaces. (2) Aerodynamic noise generated from the lower parts of cars has a major influence upon the wayside noise.

Transonic and supersonic ground effect aerodynamics

NASA Astrophysics Data System (ADS)

Doig, G.

2014-08-01

A review of recent and historical work in the field of transonic and supersonic ground effect aerodynamics has been conducted, focussing on applied research on wings and aircraft, present and future ground transportation, projectiles, rocket sleds and other related bodies which travel in close ground proximity in the compressible regime. Methods for ground testing are described and evaluated, noting that wind tunnel testing is best performed with a symmetry model in the absence of a moving ground; sled or rail testing is ultimately preferable, though considerably more expensive. Findings are reported on shock-related ground influence on aerodynamic forces and moments in and accelerating through the transonic regime - where force reversals and the early onset of local supersonic flow is prevalent - as well as more predictable behaviours in fully supersonic to hypersonic ground effect flows.

A Unit-Problem Investigation of Blunt Leading-Edge Separation Motivated by AVT-161 SACCON Research

NASA Technical Reports Server (NTRS)

Luckring, James M.; Boelens, Okko J.

2011-01-01

A research effort has been initiated to examine in more detail some of the challenging flow fields discovered from analysis of the SACCON configuration aerodynamics. This particular effort is oriented toward a diamond wing investigation specifically designed to isolate blunt leading-edge separation phenomena relevant to the SACCON investigations of the present workshop. The approach taken to design this new effort is reviewed along with the current status of the program.

Fast-Running Aeroelastic Code Based on Unsteady Linearized Aerodynamic Solver Developed

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Bakhle, Milind A.; Keith, T., Jr.

2003-01-01

The NASA Glenn Research Center has been developing aeroelastic analyses for turbomachines for use by NASA and industry. An aeroelastic analysis consists of a structural dynamic model, an unsteady aerodynamic model, and a procedure to couple the two models. The structural models are well developed. Hence, most of the development for the aeroelastic analysis of turbomachines has involved adapting and using unsteady aerodynamic models. Two methods are used in developing unsteady aerodynamic analysis procedures for the flutter and forced response of turbomachines: (1) the time domain method and (2) the frequency domain method. Codes based on time domain methods require considerable computational time and, hence, cannot be used during the design process. Frequency domain methods eliminate the time dependence by assuming harmonic motion and, hence, require less computational time. Early frequency domain analyses methods neglected the important physics of steady loading on the analyses for simplicity. A fast-running unsteady aerodynamic code, LINFLUX, which includes steady loading and is based on the frequency domain method, has been modified for flutter and response calculations. LINFLUX, solves unsteady linearized Euler equations for calculating the unsteady aerodynamic forces on the blades, starting from a steady nonlinear aerodynamic solution. First, we obtained a steady aerodynamic solution for a given flow condition using the nonlinear unsteady aerodynamic code TURBO. A blade vibration analysis was done to determine the frequencies and mode shapes of the vibrating blades, and an interface code was used to convert the steady aerodynamic solution to a form required by LINFLUX. A preprocessor was used to interpolate the mode shapes from the structural dynamic mesh onto the computational dynamics mesh. Then, we used LINFLUX to calculate the unsteady aerodynamic forces for a given mode, frequency, and phase angle. A postprocessor read these unsteady pressures and

Physics Education Research efforts to promote diversity: Challenges and opportunities

NASA Astrophysics Data System (ADS)

Brahmia, Suzanne

2015-04-01

We begin this talk with a brief description of the gender and ethnic diversity of the physics community. We then discuss several current efforts within Physics Education Research that have the potential to further our understanding of issues surrounding underrepresentation. These efforts include research into (1) the role of community and strategies for developing effective communities; (2) physics identity and self-efficacy; (3) the affordances that students from underrepresented groups bring to physics learning; (4) socioeconomics and its impact on mathematization. One of the challenges to conducting this research is the relatively small proportion of underrepresented minority students in current physics classes, and the small number of women in physics and engineering majors. In collaboration with Stephen Kanim, New Mexico State University.

A Survey of Challenges in Aerodynamic Exhaust Nozzle Technology for Aerospace Propulsion Applications

NASA Technical Reports Server (NTRS)

Shyne, Rickey J.

2002-01-01

The current paper discusses aerodynamic exhaust nozzle technology challenges for aircraft and space propulsion systems. Technology advances in computational and experimental methods have led to more accurate design and analysis tools, but many major challenges continue to exist in nozzle performance, jet noise and weight reduction. New generations of aircraft and space vehicle concepts dictate that exhaust nozzles have optimum performance, low weight and acceptable noise signatures. Numerous innovative nozzle concepts have been proposed for advanced subsonic, supersonic and hypersonic vehicle configurations such as ejector, mixer-ejector, plug, single expansion ramp, altitude compensating, lobed and chevron nozzles. This paper will discuss the technology barriers that exist for exhaust nozzles as well as current research efforts in place to address the barriers.

Use of water towing tanks for aerodynamics and hydrodynamics

NASA Technical Reports Server (NTRS)

Gadelhak, Mohamed

1987-01-01

Wind tunnels and flumes have become standard laboratory tools for modeling a variety of aerodynamic and hydrodynamic flow problems. Less available, although by no means less useful, are facilities in which a model can be towed (or propelled) through air or water. This article emphasizes the use of the water towing tank as an experimental tool for aerodynamic and hydrodynamic studies. Its advantages and disadvantages over other flow rigs are discussed, and its usefullness is illustrated through many examples of research results obtained over the past few years in a typical towing tank facility.

The Effects of Surfaces on the Aerodynamics and Acoustics of Jet Flows

NASA Technical Reports Server (NTRS)

Smith, Matthew J.; Miller, Steven A. E.

2013-01-01

Aircraft noise mitigation is an ongoing challenge for the aeronautics research community. In response to this challenge, low-noise aircraft concepts have been developed that exhibit situations where the jet exhaust interacts with an airframe surface. Jet flows interacting with nearby surfaces manifest a complex behavior in which acoustic and aerodynamic characteristics are altered. In this paper, the variation of the aerodynamics, acoustic source, and far-field acoustic intensity are examined as a large at plate is positioned relative to the nozzle exit. Steady Reynolds-Averaged Navier-Stokes solutions are examined to study the aerodynamic changes in the field-variables and turbulence statistics. The mixing noise model of Tam and Auriault is used to predict the noise produced by the jet. To validate both the aerodynamic and the noise prediction models, results are compared with Particle Image Velocimetry (PIV) and free-field acoustic data respectively. The variation of the aerodynamic quantities and noise source are examined by comparing predictions from various jet and at plate configurations with an isolated jet. To quantify the propulsion airframe aeroacoustic installation effects on the aerodynamic noise source, a non-dimensional number is formed that contains the flow-conditions and airframe installation parameters.

Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

NASA Image and Video Library

2017-02-15

Ashley Karp, NASA JPL (Left) and Hunjoo Kim, NASA JPL (Right) attaching heat sensors the Peregrine Hybrid Rocket Engine prior to its test at the Outdoor Aerodynamic Research Facility (OARF, N-249) at NASA's Ames Research Center.

September 2002 Working Group Meeting on Heavy Vehicle Aerodynamic Drag: Presentations and Summary of Comments and Conclusions

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

McCallen, R

2002-09-01

A Working Group Meeting on Heavy Vehicle Aerodynamic Drag was held at NASA Ames Research Center on September 23, 2002. The purpose of the meeting was to present and discuss technical details on the experimental and computational work in progress and future project plans. Representatives from the Department of Energy (DOE)/Office of Energy Efficiency and Renewable Energy/Office of FreedomCAR & Vehicle Technologies, Lawrence Livermore National Laboratory (LLNL), Sandia National Laboratories (SNL), NASA Ames Research Center (NASA), University of Southern California (USC), California Institute of Technology (Caltech), Georgia Tech Research Institute (GTRI), Argonne National Laboratory (ANL), Freightliner, and Portland State Universitymore » participated in the meeting. This report contains the technical presentations (viewgraphs) delivered at the Meeting, briefly summarizes the comments and conclusions, and outlines the future action items. The meeting began with an introduction by the Project Lead Rose McCallen of LLNL, where she emphasized that the world energy consumption is predicted to relatively soon exceed the available resources (i.e., fossil, hydro, non-breeder fission). This short fall is predicted to begin around the year 2050. Minimizing vehicle aerodynamic drag will significantly reduce our Nation's dependence on foreign oil resources and help with our world-wide fuel shortage. Rose also mentioned that educating the populace and researchers as to our world energy issues is important and that our upcoming United Engineering Foundation (UEF) Conference on ''The Aerodynamics of Heavy Vehicles: Trucks, Busses, and Trains'' was one way our DOE Consortium was doing this. Mentioned were the efforts of Fred Browand from USC in organizing and attracting internationally recognized speakers to the Conference. Rose followed with an overview of the DOE project goals, deliverables, and FY03 activities. The viewgraphs are attached at the end of this report. Sid Diamond

Aerodynamic Shutoff Valve

NASA Technical Reports Server (NTRS)

Horstman, Raymond H.

1992-01-01

Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

Aerodynamic configuration development of the highly maneuverable aircraft technology remotely piloted research vehicle

NASA Technical Reports Server (NTRS)

Gingrich, P. B.; Child, R. D.; Panageas, G. N.

1977-01-01

The aerodynamic development of the highly maneuverable aircraft technology remotely piloted research vehicle (HiMAT/RPRV) from the conceptual design to the final configuration is presented. The design integrates several advanced concepts to achieve a high degree of transonic maneuverability, and was keyed to sustained maneuverability goals while other fighter typical performance characteristics were maintained. When tests of the baseline configuration indicated deficiencies in the technology integration and design techniques, the vehicle was reconfigured to satisfy the subcritical and supersonic requirements. Drag-due-to-lift levels only 5 percent higher than the optimum were obtained for the wind tunnel model at a lift coefficient of 1 for Mach numbers of up to 0.8. The transonic drag rise was progressively lowered with the application of nonlinear potential flow analyses coupled with experimental data.

Aerodynamical Probation Of Semi-Industrial Production Plant For Centrifugal Dust Collectors’ Efficiency Research

NASA Astrophysics Data System (ADS)

Buligin, Y. I.; Zharkova, M. G.; Alexeenko, L. N.

2017-01-01

In previous studies, experiments were carried out on the small-size models of cyclonic units, but now there completed the semi-industrial pilot plant ≪Cyclone≫, which would allow comparative testing of real samples of different shaped centrifugal dust-collectors and compare their efficiency. This original research plant is patented by authors. The aim of the study is to improve efficiency of exhaust gases collecting process, by creating improved designs of centrifugal dust collectors, providing for the possibility of regulation constructive parameters depending on the properties and characteristics of air-fuel field. The objectives of the study include identifying and studying the cyclonic apparatus association constructive parameters with their aerodynamic characteristics and dust-collecting efficiency. The article is very relevant, especially for future practical application of its results in dust removal technology.

Overview of the Cranked-Arrow Wing Aerodynamics Project International

NASA Technical Reports Server (NTRS)

Obara, Clifford J.; Lamar, John E.

2008-01-01

This paper provides a brief history of the F-16XL-1 aircraft, its role in the High Speed Research program and how it was morphed into the Cranked Arrow Wing Aerodynamics Project. Various flight, wind-tunnel and Computational Fluid Dynamics data sets were generated as part of the project. These unique and open flight datasets for surface pressures, boundary-layer profiles and skin-friction distributions, along with surface flow data, are described and sample data comparisons given. This is followed by a description of how the project became internationalized to be known as Cranked Arrow Wing Aerodynamics Project International and is concluded by an introduction to the results of a four year computational predictive study of data collected at flight conditions by participating researchers.

The Influence of Hoop Diameter on Aerodynamic Performance of O-Ring Paper Plane

NASA Astrophysics Data System (ADS)

Ismail, N. I.; Sharudin, Hazim; Talib, R. J.; Hassan, A. A.; Yusoff, H.

2018-05-01

The O-ring paper plane can be categorized as one of the Micro Air Vehicle (MAV) based on their characteristics and size. However, the aerodynamics performance of the O-ring paper plane was not fully discovered by previous researchers due to its aerodynamics complexity and various hoop diameters. Thus, the objective of this research is to study the influence of hoop diameters towards the aerodynamics performance of O-ring paper plane. In this works, three types of O-ring paper plane known as Design 1, 2 and 3 with different hoop diameter were initially developed by using the ANSYS-Design Modeler. All the design was analyzed based on aerodynamic simulations works executed on ANSYS-CFX solver. The results suggested that Design 3 (with larger hoop size) produced better CL, CLmax and AoAstall magnitude compared to other design. In fact, O-ring paper plane with larger hoop size configurations showed potential in providing at least 5.2% and 5.9% better performance in stability (ΔCM/ΔCL) and aerodynamic efficiency (CL/CDmax), respectively. Despite the advantages found in lift performances, however, O-ring paper plane with larger hoop size configurations slightly suffered from larger drag increment (CDincrement) compared to smaller hoop size configurations. Based on these results, it can be presumed that O-Ring paper plane with larger hoop sizes contributed into better lift, stability and aerodynamic efficiency performances but slightly suffered from larger drag penalty.

Effect of static shape deformation on aerodynamics and aerothermodynamics of hypersonic inflatable aerodynamic decelerator

NASA Astrophysics Data System (ADS)

Guo, Jinghui; Lin, Guiping; Bu, Xueqin; Fu, Shiming; Chao, Yanmeng

2017-07-01

The inflatable aerodynamic decelerator (IAD), which allows heavier and larger payloads and offers flexibility in landing site selection at higher altitudes, possesses potential superiority in next generation space transport system. However, due to the flexibilities of material and structure assembly, IAD inevitably experiences surface deformation during atmospheric entry, which in turn alters the flowfield around the vehicle and leads to the variations of aerodynamics and aerothermodynamics. In the current study, the effect of the static shape deformation on the hypersonic aerodynamics and aerothermodynamics of a stacked tori Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is demonstrated and analyzed in detail by solving compressible Navier-Stokes equations with Menter's shear stress transport (SST) turbulence model. The deformed shape is obtained by structural modeling in the presence of maximum aerodynamic pressure during entry. The numerical results show that the undulating shape deformation makes significant difference to flow structure. In particular, the more curved outboard forebody surface results in local flow separations and reattachments in valleys, which consequently yields remarkable fluctuations of surface conditions with pressure rising in valleys yet dropping on crests while shear stress and heat flux falling in valleys yet rising on crests. Accordingly, compared with the initial (undeformed) shape, the corresponding differences of surface conditions get more striking outboard, with maximum augmentations of 379 pa, 2224 pa, and 19.0 W/cm2, i.e., 9.8%, 305.9%, and 101.6% for the pressure, shear stress and heat flux respectively. Moreover, it is found that, with the increase of angle of attack, the aerodynamic characters and surface heating vary and the aeroheating disparities are evident between the deformed and initial shape. For the deformable HIAD model investigated in this study, the more intense surface conditions and changed flight

Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

NASA Image and Video Library

2017-02-15

Hunjoo Kim, NASA JPL (Left) and Ashley Karp, NASA JPL (Right) attaching heat sensors the Peregrine Hybrid Rocket Engine prior to its test at the Outdoor Aerodynamic Research Facility (OARF, N-249) at NASA’s Ames Research Center.

Control of flow separation and mixing by aerodynamic excitation

NASA Technical Reports Server (NTRS)

Rice, Edward J.; Abbott, John M.

1990-01-01

The recent research in the control of shear flows using unsteady aerodynamic excitation conducted at the NASA Lewis Research Center is reviewed. The program is of a fundamental nature, concentrating on the physics of the unsteady aerodynamic processes. This field of research is a fairly new development with great promise in the areas of enhanced mixing and flow separation control. Enhanced mixing research includes influence of core turbulence, forced pairing of coherent structures, and saturation of mixing enhancement. Separation flow control studies included are for a two-dimensional diffuser, conical diffusers, and single airfoils. Ultimate applications include aircraft engine inlet flow control at high angle of attack, wide angle diffusers, highly loaded airfoils as in turbomachinery, and ejector/suppressor nozzles for the supersonic transport. An argument involving the Coanda Effect is made that all of the above mentioned application areas really only involve forms of shear layer mixing enhancement. The program also includes the development of practical excitation devices which might be used in aircraft applications.

Tobacco Industry Efforts to Undermine Policy-Relevant Research

PubMed Central

Landman, Anne

2009-01-01

The tobacco industry, working through third parties to prevent policy-relevant research that adversely affected it between 1988 and 1998, used coordinated, well-funded strategies in repeated attempts to silence tobacco researcher Stanton A. Glantz. Tactics included advertising, litigation, and attempts to have the US Congress cut off the researcher's National Cancer Institute funding. Efforts like these can influence the policymaking process by silencing opposing voices and discouraging other scientists from doing work that may expose them to tobacco industry attacks. The support of highly credible public health organizations and of researchers’ employers is crucial to the continued advancement of public health. PMID:19008508

Langley Symposium on Aerodynamics, volume 1

NASA Technical Reports Server (NTRS)

Stack, Sharon H. (Compiler)

1986-01-01

The purpose of this work was to present current work and results of the Langley Aeronautics Directorate covering the areas of computational fluid dynamics, viscous flows, airfoil aerodynamics, propulsion integration, test techniques, and low-speed, high-speed, and transonic aerodynamics. The following sessions are included in this volume: theoretical aerodynamics, test techniques, fluid physics, and viscous drag reduction.

What predicts dissemination efforts among public health researchers in the United States?

PubMed

Tabak, Rachel G; Stamatakis, Katherine A; Jacobs, Julie A; Brownson, Ross C

2014-01-01

We identified factors related to dissemination efforts by researchers to non-research audiences to reduce the gap between research generation and uptake in public health practice. We conducted a cross-sectional study of 266 researchers at universities, the National Institutes of Health (NIH), and CDC. We identified scientists using a search of public health journals and lists from government-sponsored research. The scientists completed a 35-item online survey in 2012. Using multivariable logistic regression, we compared self-rated effort to disseminate findings to non-research audiences (excellent/good vs. poor) across predictor variables in three categories: perceptions or reasons to disseminate, perceived expectation by employer/funders, and professional training and experience. One-third of researchers rated their dissemination efforts as poor. Many factors were significantly related to whether a researcher rated him/herself as excellent/good, including obligation to disseminate findings (odds ratio [OR] = 2.7, 95% confidence interval [CI] 1.1, 6.8), dissemination important for their department (OR=2.3, 95% CI 1.2, 4.5), dissemination expected by employer (OR=2.0, 95% CI 1.2, 3.2) or by funder (OR=2.1, 95% CI 1.3, 3.2), previous work in a practice/policy setting (OR=4.4, 95% CI 2.1, 9.3), and university researchers with Prevention Research Center affiliation vs. NIH researchers (OR=4.7, 95% CI 1.4, 15.7). With all variables in the model, dissemination expected by funder (OR=2.0, 95% CI 1.2, 3.1) and previous work in a practice/policy setting (OR=3.5, OR 1.7, 7.1) remained significant. These findings support the need for structural changes to the system, including funding agency priorities and participation of researchers in practice- and policy-based experiences, which may enhance efforts to disseminate by researchers.

In vivo recording of aerodynamic force with an aerodynamic force platform: from drones to birds.

PubMed

Lentink, David; Haselsteiner, Andreas F; Ingersoll, Rivers

2015-03-06

Flapping wings enable flying animals and biomimetic robots to generate elevated aerodynamic forces. Measurements that demonstrate this capability are based on experiments with tethered robots and animals, and indirect force calculations based on measured kinematics or airflow during free flight. Remarkably, there exists no method to measure these forces directly during free flight. Such in vivo recordings in freely behaving animals are essential to better understand the precise aerodynamic function of their flapping wings, in particular during the downstroke versus upstroke. Here, we demonstrate a new aerodynamic force platform (AFP) for non-intrusive aerodynamic force measurement in freely flying animals and robots. The platform encloses the animal or object that generates fluid force with a physical control surface, which mechanically integrates the net aerodynamic force that is transferred to the earth. Using a straightforward analytical solution of the Navier-Stokes equation, we verified that the method is accurate. We subsequently validated the method with a quadcopter that is suspended in the AFP and generates unsteady thrust profiles. These independent measurements confirm that the AFP is indeed accurate. We demonstrate the effectiveness of the AFP by studying aerodynamic weight support of a freely flying bird in vivo. These measurements confirm earlier findings based on kinematics and flow measurements, which suggest that the avian downstroke, not the upstroke, is primarily responsible for body weight support during take-off and landing.

Aerodynamic prediction techniques for hypersonic configuration design

NASA Technical Reports Server (NTRS)

1981-01-01

An investigation of approximate theoretical techniques for predicting aerodynamic characteristics and surface pressures for relatively slender vehicles at moderate hypersonic speeds was performed. Emphasis was placed on approaches that would be responsive to preliminary configuration design level of effort. Potential theory was examined in detail to meet this objective. Numerical pilot codes were developed for relatively simple three dimensional geometries to evaluate the capability of the approximate equations of motion considered. Results from the computations indicate good agreement with higher order solutions and experimental results for a variety of wing, body, and wing-body shapes for values of the hypersonic similarity parameter M delta approaching one.

Basic Aerodynamics of Combustion Chambers,

DTIC Science & Technology

1981-05-20

engineering circles, the trend in the design of new tyres of combustion chambers is to combine the use of aerodynamics , ;he science of heat transfer and...7. FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AF8 ON F/6 21/2 BASIC AERODYNAMICS OF COMBUSTION CHAMBERS,(U) MAY 81 N HUANG UNCLASSIFIED FTD-ID(RS)T...160󈨔 NL so EEEEEE 0hEEEEEEmollllmmlllll mEImmmmmEEE mEEEEEmmEEmmmE IilillilillEEE FTD-1D(RS)T-1684-80 FOREIGN TECHNOLOGY DIVISION BASIC AERODYNAMICS CF

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.

TRO-2D - A code for rational transonic aerodynamic optimization

NASA Technical Reports Server (NTRS)

Davis, W. H., Jr.

1985-01-01

Features and sample applications of the transonic rational optimization (TRO-2D) code are outlined. TRO-2D includes the airfoil analysis code FLO-36, the CONMIN optimization code and a rational approach to defining aero-function shapes for geometry modification. The program is part of an effort to develop an aerodynamically smart optimizer that will simplify and shorten the design process. The user has a selection of drag minimization and associated minimum lift, moment, and the pressure distribution, a choice among 14 resident aero-function shapes, and options on aerodynamic and geometric constraints. Design variables such as the angle of attack, leading edge radius and camber, shock strength and movement, supersonic pressure plateau control, etc., are discussed. The results of calculations of a reduced leading edge camber transonic airfoil and an airfoil with a natural laminar flow are provided, showing that only four design variables need be specified to obtain satisfactory results.

Aerodynamic Parameter Estimation for the X-43A (Hyper-X) from Flight Data

NASA Technical Reports Server (NTRS)

Morelli, Eugene A.; Derry, Stephen D.; Smith, Mark S.

2005-01-01

Aerodynamic parameters were estimated based on flight data from the third flight of the X-43A hypersonic research vehicle, also called Hyper-X. Maneuvers were flown using multiple orthogonal phase-optimized sweep inputs applied as simultaneous control surface perturbations at Mach 8, 7, 6, 5, 4, and 3 during the vehicle descent. Aerodynamic parameters, consisting of non-dimensional longitudinal and lateral stability and control derivatives, were estimated from flight data at each Mach number. Multi-step inputs at nearly the same flight conditions were also flown to assess the prediction capability of the identified models. Prediction errors were found to be comparable in magnitude to the modeling errors, which indicates accurate modeling. Aerodynamic parameter estimates were plotted as a function of Mach number, and compared with estimates from the pre-flight aerodynamic database, which was based on wind-tunnel tests and computational fluid dynamics. Agreement between flight estimates and values computed from the aerodynamic database was excellent overall.

On Wings: Aerodynamics of Eagles.

ERIC Educational Resources Information Center

Millson, David

2000-01-01

The Aerodynamics Wing Curriculum is a high school program that combines basic physics, aerodynamics, pre-engineering, 3D visualization, computer-assisted drafting, computer-assisted manufacturing, production, reengineering, and success in a 15-hour, 3-week classroom module. (JOW)

Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

NASA Image and Video Library

2017-02-15

From Left to Right: Ashley Karp (NASA JPL), Hunjoo Kim (NASA JPL), Brian Schratz (NASA JPL) and Kyle Botteon (NASA JPL) Testing the Peregrine Hybrid Rocket Engine at the Outdoor Aerodynamic Research Facility (building N249, OARF) at NASA’s Ames Research Center.

Computational aerodynamics and artificial intelligence

NASA Technical Reports Server (NTRS)

Mehta, U. B.; Kutler, P.

1984-01-01

The general principles of artificial intelligence are reviewed and speculations are made concerning how knowledge based systems can accelerate the process of acquiring new knowledge in aerodynamics, how computational fluid dynamics may use expert systems, and how expert systems may speed the design and development process. In addition, the anatomy of an idealized expert system called AERODYNAMICIST is discussed. Resource requirements for using artificial intelligence in computational fluid dynamics and aerodynamics are examined. Three main conclusions are presented. First, there are two related aspects of computational aerodynamics: reasoning and calculating. Second, a substantial portion of reasoning can be achieved with artificial intelligence. It offers the opportunity of using computers as reasoning machines to set the stage for efficient calculating. Third, expert systems are likely to be new assets of institutions involved in aeronautics for various tasks of computational aerodynamics.

Status, Plans and Initial Results for Ares I Crew Launch Vehicle Aerodynamics

NASA Technical Reports Server (NTRS)

Huebner, Lawrence D.; Hall, Robert M.; Haynes, Davy A.; Pamadi, Bandu N.; Taylor, Terry L.; Seaford, C. Mark

2008-01-01

Following the completion of NASA s Exploration Systems Architecture Study in August 2004 for the NASA Exploration Systems Mission Directorate (ESMD), the Ares Projects Office at the NASA Marshall Space Flight Center was assigned project management responsibilities for the design and development of the first vehicle in the architecture, the Ares I Crew Launch Vehicle (CLV), which will be used to launch astronauts to low earth orbit and rendezvous with either the International Space Station or the ESMD s earth departure stage for lunar or other future missions beyond low Earth orbit. The primary elements of the Ares I CLV project are the first stage, the upper stage, the upper stage engine, and vehicle integration. Within vehicle integration is an effort in integrated design and analysis which is comprised of a number of technical disciplines needed to support vehicle design and development. One of the important disciplines throughout the life of the project is aerodynamics. This paper will present the status, plans, and initial results of Ares I CLV aerodynamics as the project was preparing for the Ares I CLV Systems Requirements Review. Following a discussion of the specific interactions with other technical panels and a status of the current activities, the plans for aerodynamic support of the Ares I CLV until the initial crewed flights will be presented. Keywords: Ares I Crew Launch Vehicle, aerodynamics, wind tunnel testing, computational fluid dynamics

Researchers Rebuild their Effort to Rebuild the Internet

ERIC Educational Resources Information Center

Young, Jeffrey R.

2008-01-01

Reinveting the Internet is not easy. Researchers working on a federally supported effort to design a replacement recently had to go back to the drawing board. They now think the best way to do it is to try several "best ways" instead of searching for just one--and to invite help from social scientists rather than just self-described computer…

Nonlinear Aerodynamic Modeling From Flight Data Using Advanced Piloted Maneuvers and Fuzzy Logic

NASA Technical Reports Server (NTRS)

Brandon, Jay M.; Morelli, Eugene A.

2012-01-01

Results of the Aeronautics Research Mission Directorate Seedling Project Phase I research project entitled "Nonlinear Aerodynamics Modeling using Fuzzy Logic" are presented. Efficient and rapid flight test capabilities were developed for estimating highly nonlinear models of airplane aerodynamics over a large flight envelope. Results showed that the flight maneuvers developed, used in conjunction with the fuzzy-logic system identification algorithms, produced very good model fits of the data, with no model structure inputs required, for flight conditions ranging from cruise to departure and spin conditions.

Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

NASA Image and Video Library

2017-02-15

From Left to Right: 1. Hunjoo Kim (NASA JPL) 2. Kyle Botteon (NASA JPL) 3. Ashley Karp (NASA JPL) 4. Brian Schratz (NASA JPL) Testing the Peregrine Hybrid Rocket Engine at the Outdoor Aerodynamic Research Facility (building N249, OARF) at Ames Research Center.

Characterization of physical and aerodynamic properties of walnuts

USDA-ARS?s Scientific Manuscript database

The objective of this research was to study the physical and aerodynamic properties of freshly harvested walnuts. Measurements were carried out for three walnut varieties, Tulare, Howard and Chandler cultivated in California, USA. The nuts treated with and without Ethephon were collected from mechan...

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.

Future Challenges and Opportunities in Aerodynamics

NASA Technical Reports Server (NTRS)

Kumar, Ajay; Hefner, Jerry N.

2000-01-01

Investments in aeronautics research and technology have declined substantially over the last decade, in part due to the perception that technologies required in aircraft design are fairly mature and readily available. This perception is being driven by the fact that aircraft configurations, particularly the transport aircraft, have evolved only incrementally, over last several decades. If however, one considers that the growth in air travel is expected to triple in the next 20 years, it becomes quickly obvious that the evolutionary development of technologies is not going to meet the increased demands for safety, environmental compatibility, capacity, and economic viability. Instead, breakthrough technologies will he required both in traditional disciplines of aerodynamics, propulsion, structures, materials, controls, and avionics as well as in the multidisciplinary integration of these technologies into the design of future aerospace vehicles concepts. The paper discusses challenges and opportunities in the field of aerodynamics over the next decade. Future technology advancements in aerodynamics will hinge on our ability, to understand, model, and control complex, three-dimensional, unsteady viscous flow across the speed range. This understanding is critical for developing innovative flow and noise control technologies and advanced design tools that will revolutionize future aerospace vehicle systems and concepts. Specifically, the paper focuses on advanced vehicle concepts, flow and noise control technologies, and advanced design and analysis tools.

Aerodynamic sampling for landmine trace detection

NASA Astrophysics Data System (ADS)

Settles, Gary S.; Kester, Douglas A.

2001-10-01

Electronic noses and similar sensors show promise for detecting buried landmines through the explosive trace signals they emit. A key step in this detection is the sampler or sniffer, which acquires the airborne trace signal and presents it to the detector. Practicality demands no physical contact with the ground. Further, both airborne particulates and molecular traces must be sampled. Given a complicated minefield terrain and microclimate, this becomes a daunting chore. Our prior research on canine olfactory aerodynamics revealed several ways that evolution has dealt with such problems: 1) proximity of the sniffer to the scent source is important, 2) avoid exhaling back into the scent source, 3) use an aerodynamic collar on the sniffer inlet, 4) use auxiliary airjets to stir up surface particles, and 5) manage the 'impedance mismatch' between sniffer and sensor airflows carefully. Unfortunately, even basic data on aerodynamic sniffer performance as a function of inlet-tube and scent-source diameters, standoff distance, etc., have not been previously obtained. A laboratory-prototype sniffer was thus developed to provide guidance for landmine trace detectors. Initial experiments with this device are the subject of this paper. For example, a spike in the trace signal is observed upon starting the sniffer airflow, apparently due to rapid depletion of the available signal-laden air. Further, shielding the sniffer from disruptive ambient airflows arises as a key issue in sampling efficiency.

Aerodynamic drag on intermodal railcars

NASA Astrophysics Data System (ADS)

Kinghorn, Philip; Maynes, Daniel

2014-11-01

The aerodynamic drag associated with transport of commodities by rail is becoming increasingly important as the cost of diesel fuel increases. This study aims to increase the efficiency of intermodal cargo trains by reducing the aerodynamic drag on the load carrying cars. For intermodal railcars a significant amount of aerodynamic drag is a result of the large distance between loads that often occurs and the resulting pressure drag resulting from the separated flow. In the present study aerodynamic drag data have been obtained through wind tunnel testing on 1/29 scale models to understand the savings that may be realized by judicious modification to the size of the intermodal containers. The experiments were performed in the BYU low speed wind tunnel and the test track utilizes two leading locomotives followed by a set of five articulated well cars with double stacked containers. The drag on a representative mid-train car is measured using an isolated load cell balance and the wind tunnel speed is varied from 20 to 100 mph. We characterize the effect that the gap distance between the containers and the container size has on the aerodynamic drag of this representative rail car and investigate methods to reduce the gap distance.

Aerodynamic shape optimization using preconditioned conjugate gradient methods

NASA Technical Reports Server (NTRS)

Burgreen, Greg W.; Baysal, Oktay

1993-01-01

In an effort to further improve upon the latest advancements made in aerodynamic shape optimization procedures, a systematic study is performed to examine several current solution methodologies as applied to various aspects of the optimization procedure. It is demonstrated that preconditioned conjugate gradient-like methodologies dramatically decrease the computational efforts required for such procedures. The design problem investigated is the shape optimization of the upper and lower surfaces of an initially symmetric (NACA-012) airfoil in inviscid transonic flow and at zero degree angle-of-attack. The complete surface shape is represented using a Bezier-Bernstein polynomial. The present optimization method then automatically obtains supercritical airfoil shapes over a variety of freestream Mach numbers. Furthermore, the best optimization strategy examined resulted in a factor of 8 decrease in computational time as well as a factor of 4 decrease in memory over the most efficient strategies in current use.

Hypersonic Inflatable Aerodynamic Decelerator Ground Test Development

NASA Technical Reports Server (NTRS)

Del Corso, Jospeh A.; Hughes, Stephen; Cheatwood, Neil; Johnson, Keith; Calomino, Anthony

2015-01-01

Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology readiness levels have been incrementally matured by NASA over the last thirteen years, with most recent support from NASA's Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP). Recently STMD GCDP has authorized funding and support through fiscal year 2015 (FY15) for continued HIAD ground developments which support a Mars Entry, Descent, and Landing (EDL) study. The Mars study will assess the viability of various EDL architectures to enable a Mars human architecture pathfinder mission planned for mid-2020. At its conclusion in November 2014, NASA's first HIAD ground development effort had demonstrated success with fabricating a 50 W/cm2 modular thermal protection system, a 400 C capable inflatable structure, a 10-meter scale aeroshell manufacturing capability, together with calibrated thermal and structural models. Despite the unquestionable success of the first HIAD ground development effort, it was recognized that additional investment was needed in order to realize the full potential of the HIAD technology capability to enable future flight opportunities. The second HIAD ground development effort will focus on extending performance capability in key technology areas that include thermal protection system, lifting-body structures, inflation systems, flight control, stage transitions, and 15-meter aeroshell scalability. This paper presents an overview of the accomplishments under the baseline HIAD development effort and current plans for a follow-on development effort focused on extending those critical technologies needed to enable a Mars Pathfinder mission.

Estimation of Unsteady Aerodynamic Models from Dynamic Wind Tunnel Data

NASA Technical Reports Server (NTRS)

Murphy, Patrick; Klein, Vladislav

2011-01-01

Demanding aerodynamic modelling requirements for military and civilian aircraft have motivated researchers to improve computational and experimental techniques and to pursue closer collaboration in these areas. Model identification and validation techniques are key components for this research. This paper presents mathematical model structures and identification techniques that have been used successfully to model more general aerodynamic behaviours in single-degree-of-freedom dynamic testing. Model parameters, characterizing aerodynamic properties, are estimated using linear and nonlinear regression methods in both time and frequency domains. Steps in identification including model structure determination, parameter estimation, and model validation, are addressed in this paper with examples using data from one-degree-of-freedom dynamic wind tunnel and water tunnel experiments. These techniques offer a methodology for expanding the utility of computational methods in application to flight dynamics, stability, and control problems. Since flight test is not always an option for early model validation, time history comparisons are commonly made between computational and experimental results and model adequacy is inferred by corroborating results. An extension is offered to this conventional approach where more general model parameter estimates and their standard errors are compared.

Aerodynamics of High-Lift Configuration Civil Aircraft Model in JAXA

NASA Astrophysics Data System (ADS)

Yokokawa, Yuzuru; Murayama, Mitsuhiro; Ito, Takeshi; Yamamoto, Kazuomi

This paper presents basic aerodynamics and stall characteristics of the high-lift configuration aircraft model JSM (JAXA Standard Model). During research process of developing high-lift system design method, wind tunnel testing at JAXA 6.5m by 5.5m low-speed wind tunnel and Navier-Stokes computation on unstructured hybrid mesh were performed for a realistic configuration aircraft model equipped with high-lift devices, fuselage, nacelle-pylon, slat tracks and Flap Track Fairings (FTF), which was assumed 100 passenger class modern commercial transport aircraft. The testing and the computation aimed to understand flow physics and then to obtain some guidelines for designing a high performance high-lift system. As a result of the testing, Reynolds number effects within linear region and stall region were observed. Analysis of static pressure distribution and flow visualization gave the knowledge to understand the aerodynamic performance. CFD could capture the whole characteristics of basic aerodynamics and clarify flow mechanism which governs stall characteristics even for complicated geometry and its flow field. This collaborative work between wind tunnel testing and CFD is advantageous for improving or has improved the aerodynamic performance.

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.

Transonic aerodynamic design experience

NASA Technical Reports Server (NTRS)

Bonner, E.

1989-01-01

Advancements have occurred in transonic numerical simulation that place aerodynamic performance design into a relatively well developed status. Efficient broad band operating characteristics can be reliably developed at the conceptual design level. Recent aeroelastic and separated flow simulation results indicate that systematic consideration of an increased range of design problems appears promising. This emerging capability addresses static and dynamic structural/aerodynamic coupling and nonlinearities associated with viscous dominated flows.

Aerodynamic effects of flexibility in flapping wings.

PubMed

Zhao, Liang; Huang, Qingfeng; Deng, Xinyan; Sane, Sanjay P

2010-03-06

Recent work on the aerodynamics of flapping flight reveals fundamental differences in the mechanisms of aerodynamic force generation between fixed and flapping wings. When fixed wings translate at high angles of attack, they periodically generate and shed leading and trailing edge vortices as reflected in their fluctuating aerodynamic force traces and associated flow visualization. In contrast, wings flapping at high angles of attack generate stable leading edge vorticity, which persists throughout the duration of the stroke and enhances mean aerodynamic forces. Here, we show that aerodynamic forces can be controlled by altering the trailing edge flexibility of a flapping wing. We used a dynamically scaled mechanical model of flapping flight (Re approximately 2000) to measure the aerodynamic forces on flapping wings of variable flexural stiffness (EI). For low to medium angles of attack, as flexibility of the wing increases, its ability to generate aerodynamic forces decreases monotonically but its lift-to-drag ratios remain approximately constant. The instantaneous force traces reveal no major differences in the underlying modes of force generation for flexible and rigid wings, but the magnitude of force, the angle of net force vector and centre of pressure all vary systematically with wing flexibility. Even a rudimentary framework of wing veins is sufficient to restore the ability of flexible wings to generate forces at near-rigid values. Thus, the magnitude of force generation can be controlled by modulating the trailing edge flexibility and thereby controlling the magnitude of the leading edge vorticity. To characterize this, we have generated a detailed database of aerodynamic forces as a function of several variables including material properties, kinematics, aerodynamic forces and centre of pressure, which can also be used to help validate computational models of aeroelastic flapping wings. These experiments will also be useful for wing design for small

Aerodynamic effects of flexibility in flapping wings

PubMed Central

Zhao, Liang; Huang, Qingfeng; Deng, Xinyan; Sane, Sanjay P.

2010-01-01

Recent work on the aerodynamics of flapping flight reveals fundamental differences in the mechanisms of aerodynamic force generation between fixed and flapping wings. When fixed wings translate at high angles of attack, they periodically generate and shed leading and trailing edge vortices as reflected in their fluctuating aerodynamic force traces and associated flow visualization. In contrast, wings flapping at high angles of attack generate stable leading edge vorticity, which persists throughout the duration of the stroke and enhances mean aerodynamic forces. Here, we show that aerodynamic forces can be controlled by altering the trailing edge flexibility of a flapping wing. We used a dynamically scaled mechanical model of flapping flight (Re ≈ 2000) to measure the aerodynamic forces on flapping wings of variable flexural stiffness (EI). For low to medium angles of attack, as flexibility of the wing increases, its ability to generate aerodynamic forces decreases monotonically but its lift-to-drag ratios remain approximately constant. The instantaneous force traces reveal no major differences in the underlying modes of force generation for flexible and rigid wings, but the magnitude of force, the angle of net force vector and centre of pressure all vary systematically with wing flexibility. Even a rudimentary framework of wing veins is sufficient to restore the ability of flexible wings to generate forces at near-rigid values. Thus, the magnitude of force generation can be controlled by modulating the trailing edge flexibility and thereby controlling the magnitude of the leading edge vorticity. To characterize this, we have generated a detailed database of aerodynamic forces as a function of several variables including material properties, kinematics, aerodynamic forces and centre of pressure, which can also be used to help validate computational models of aeroelastic flapping wings. These experiments will also be useful for wing design for small robotic

MARS Mission research center

NASA Technical Reports Server (NTRS)

1991-01-01

The Mars Mission Research Center (M2RC) is one of nine University Space Engineering Research Centers established by NASA in June 1988. It is a cooperative effort between NCSU and A&T in Greensboro. The goal of the Center is to focus on research and educational technologies for planetary exploration with particular emphasis on Mars. The research combines Mission Analysis and Design, Hypersonic Aerodynamics and Propulsion, Structures and Controls, Composite Materials, and Fabrication Methods in a cross-disciplined program directed towards the development of space transportation systems for lunar and planetary travel. The activities of the students and faculty in the M2RC for the period 1 Jul. 1990 to 30 Jun. 1991 are described.

Peregrine Rocket Motor Test at the Ames Outdoor Aerodynamic Rese

NASA Image and Video Library

2017-02-15

(Left): Kyle Botteon (front) and Hunjpp Kim (Behind), NASA JPL. (Right): Gregory Zilliac, Advance Propulsion Technician. NASA Ames, preparing the Peregrine Hybrid Rocket Engine at the Outdoor Aerodynamic Research Facility (OARF, N-249).

Aerodynamics of Race Cars

NASA Astrophysics Data System (ADS)

Katz, Joseph

2006-01-01

Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due to the utilization of the negative lift (downforce) principle, yielding several important performance improvements. This review briefly explains the significance of the aerodynamic downforce and how it improves race car performance. After this short introduction various methods to generate downforce such as inverted wings, diffusers, and vortex generators are discussed. Due to the complex geometry of these vehicles, the aerodynamic interaction between the various body components is significant, resulting in vortex flows and lifting surface shapes unlike traditional airplane wings. Typical design tools such as wind tunnel testing, computational fluid dynamics, and track testing, and their relevance to race car development, are discussed as well. In spite of the tremendous progress of these design tools (due to better instrumentation, communication, and computational power), the fluid dynamic phenomenon is still highly nonlinear, and predicting the effect of a particular modification is not always trouble free. Several examples covering a wide range of vehicle shapes (e.g., from stock cars to open-wheel race cars) are presented to demonstrate this nonlinear nature of the flow field.

Aerodynamics of Sounding-Rocket Geometries

NASA Technical Reports Server (NTRS)

Barrowman, J.

1982-01-01

Theoretical aerodynamics program TAD predicts aerodynamic characteristics of vehicles with sounding-rocket configurations. These slender, Axisymmetric finned vehicles have a wide range of aeronautical applications from rockets to high-speed armament. TAD calculates characteristics of separate portions of vehicle, calculates interference between portions, and combines results to form total vehicle solution.

Unsteady Aerodynamic Flow Control of Moving Platforms

DTIC Science & Technology

2014-05-29

aerodynamic forces and moments effected by fluidic actuation on the flow boundaries of stationary and moving platforms. Aerodynamic forces and...Control is effected fluidically by interactions of azimuthally- and streamwise-segmented individually-addressable synthetic jet actuators with...fundamental flow mechanisms that are associated with transitory aerodynamic forces and moments effected by fluidic actuation on the flow boundaries of

On aerodynamic wake analysis and its relation to total aerodynamic drag in a wind tunnel environment

NASA Astrophysics Data System (ADS)

Guterres, Rui M.

The present work was developed with the goal of advancing the state of the art in the application of three-dimensional wake data analysis to the quantification of aerodynamic drag on a body in a low speed wind tunnel environment. Analysis of the existing tools, their strengths and limitations is presented. Improvements to the existing analysis approaches were made. Software tools were developed to integrate the analysis into a practical tool. A comprehensive derivation of the equations needed for drag computations based on three dimensional separated wake data is developed. A set of complete steps ranging from the basic mathematical concept to the applicable engineering equations is presented. An extensive experimental study was conducted. Three representative body types were studied in varying ground effect conditions. A detailed qualitative wake analysis using wake imaging and two and three dimensional flow visualization was performed. Several significant features of the flow were identified and their relation to the total aerodynamic drag established. A comprehensive wake study of this type is shown to be in itself a powerful tool for the analysis of the wake aerodynamics and its relation to body drag. Quantitative wake analysis techniques were developed. Significant post processing and data conditioning tools and precision analysis were developed. The quality of the data is shown to be in direct correlation with the accuracy of the computed aerodynamic drag. Steps are taken to identify the sources of uncertainty. These are quantified when possible and the accuracy of the computed results is seen to significantly improve. When post processing alone does not resolve issues related to precision and accuracy, solutions are proposed. The improved quantitative wake analysis is applied to the wake data obtained. Guidelines are established that will lead to more successful implementation of these tools in future research programs. Close attention is paid to

[Aerodynamic characteristics of crewman's arms during windblast].

PubMed

Zhang, Yun-ran; Wu, Gui-rong

2003-10-01

To study the aerodynamic characteristics of crewman's arms with or without protective devices in the status with raised legs or not. The experiments were performed in an FL-24 transonic and supersonic wind tunnel, over Mach number range of 0.4-2.0, with 5 degrees-30 degrees angles of attack, 0 degrees - 90 degrees sideslip angles and Re number of (0.93-3.1) x 10(6). The test model was a 1/5-scale crewman/ejection seat combination. The aerodynamic characteristics of the various sections of crewman's arms were studied and analyzed. The results showed that 1) The effect of raised leg on the aerodynamic characteristics of the crewman's arms was very evident, and was related to the status of leg raising; 2) The sideslip considerably increased aerodynamic loads on the crewman's arms, in particular when beta=50 degrees the loads was severe in the test; 3) The tested protective devices was valid, the effectiveness of wind deflector in protecting crewman's arms was evident; 4) A formula for calculating aerodynamic force acting on crewman's arms was presented. 1)The tested protective devices was valid, and the effectiveness of wind deflector in protecting crewman's arms was evident; 2) An aerodynamic basis for the development of crewman windblast protective device was presented; 3)The calculation formula presented is useful in estimating aerodynamic forces of crewman's arms.

The Automation of the Transonic Experimental Facility (TEF) and the Aerodynamic Experimental Facility (AEF)

DTIC Science & Technology

2015-10-01

ARL-TR-7506 ● OCT 2015 US Army Research Laboratory The Automation of the Transonic Experimental Facility (TEF) and the...Laboratory The Automation of the Transonic Experimental Facility (TEF) and the Aerodynamic Experimental Facility (AEF) by Charith R Ranawake Weapons...To) 05/2015–08/2015 4. TITLE AND SUBTITLE The Automation of the Transonic Experimental Facility (TEF) and the Aerodynamic Experimental Facility

Aerodynamics of sports balls

NASA Astrophysics Data System (ADS)

Mehta, R. D.

Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

Aerodynamics of sports balls

NASA Technical Reports Server (NTRS)

Mehta, R. D.

1985-01-01

Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

Generation of the Ares I-X Flight Test Vehicle Aerodynamic Data Book and Comparison To Flight

NASA Technical Reports Server (NTRS)

Bauer, Steven X.; Krist, Steven E.; Compton, William B.

2011-01-01

A 3.5-year effort to characterize the aerodynamic behavior of the Ares I-X Flight Test Vehicle (AIX FTV) is described in this paper. The AIX FTV was designed to be representative of the Ares I Crew Launch Vehicle (CLV). While there are several differences in the outer mold line from the current revision of the CLV, the overall length, mass distribution, and flight systems of the two vehicles are very similar. This paper briefly touches on each of the aerodynamic databases developed in the program, describing the methodology employed, experimental and computational contributions to the generation of the databases, and how well the databases and underlying computations compare to actual flight test results.

Low-Reynolds Number Aerodynamics of an 8.9 Percent Scale Semispan Swept Wing for Assessment of Icing Effects

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Woodard, Brian S.; Diebold, Jeffrey M.; Moens, Frederic

2017-01-01

Aerodynamic assessment of icing effects on swept wings is an important component of a larger effort to improve three-dimensional icing simulation capabilities. An understanding of ice-shape geometric fidelity and Reynolds and Mach number effects on the iced-wing aerodynamics is needed to guide the development and validation of ice-accretion simulation tools. To this end, wind-tunnel testing and computational flow simulations were carried out for an 8.9%-scale semispan wing based upon the Common Research Model airplane configuration. The wind-tunnel testing was conducted at the Wichita State University 7 ft x 10 ft Beech wind tunnel from Reynolds numbers of 0.8×10(exp 6) to 2.4×10(exp 6) and corresponding Mach numbers of 0.09 to 0.27. This paper presents the results of initial studies investigating the model mounting configuration, clean-wing aerodynamics and effects of artificial ice roughness. Four different model mounting configurations were considered and a circular splitter plate combined with a streamlined shroud was selected as the baseline geometry for the remainder of the experiments and computational simulations. A detailed study of the clean-wing aerodynamics and stall characteristics was made. In all cases, the flow over the outboard sections of the wing separated as the wing stalled with the inboard sections near the root maintaining attached flow. Computational flow simulations were carried out with the ONERA elsA software that solves the compressible, three-dimensional RANS equations. The computations were carried out in either fully turbulent mode or with natural transition. Better agreement between the experimental and computational results was obtained when considering computations with free transition compared to turbulent solutions. These results indicate that experimental evolution of the clean wing performance coefficients were due to the effect of three-dimensional transition location and that this must be taken into account for future data

Low-Reynolds Number Aerodynamics of an 8.9 Percent Scale Semispan Swept Wing for Assessment of Icing Effects

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Woodard, Brian S.; Diebold, Jeffrey M.; Moens, Frederic

2017-01-01

Aerodynamic assessment of icing effects on swept wings is an important component of a larger effort to improve three-dimensional icing simulation capabilities. An understanding of ice-shape geometric fidelity and Reynolds and Mach number effects on the iced-wing aerodynamics is needed to guide the development and validation of ice-accretion simulation tools. To this end, wind-tunnel testing and computational flow simulations were carried out for an 8.9 percent-scale semispan wing based upon the Common Research Model airplane configuration. The wind-tunnel testing was conducted at the Wichita State University 7 by 10 ft Beech wind tunnel from Reynolds numbers of 0.8×10(exp 6) to 2.4×10(exp 6) and corresponding Mach numbers of 0.09 to 0.27. This paper presents the results of initial studies investigating the model mounting configuration, clean-wing aerodynamics and effects of artificial ice roughness. Four different model mounting configurations were considered and a circular splitter plate combined with a streamlined shroud was selected as the baseline geometry for the remainder of the experiments and computational simulations. A detailed study of the clean-wing aerodynamics and stall characteristics was made. In all cases, the flow over the outboard sections of the wing separated as the wing stalled with the inboard sections near the root maintaining attached flow. Computational flow simulations were carried out with the ONERA elsA software that solves the compressible, threedimensional RANS equations. The computations were carried out in either fully turbulent mode or with natural transition. Better agreement between the experimental and computational results was obtained when considering computations with free transition compared to turbulent solutions. These results indicate that experimental evolution of the clean wing performance coefficients were due to the effect of three-dimensional transition location and that this must be taken into account for future

Payload vehicle aerodynamic reentry analysis

NASA Astrophysics Data System (ADS)

Tong, Donald

An approach for analyzing the dynamic behavior of a cone-cylinder payload vehicle during reentry to insure proper deployment of the parachute system and recovery of the payload is presented. This analysis includes the study of an aerodynamic device that is useful in extending vehicle axial rotation through the maximum dynamic pressure region. Attention is given to vehicle configuration and reentry trajectory, the derivation of pitch static aerodynamics, the derivation of the pitch damping coefficient, pitching moment modeling, aerodynamic roll device modeling, and payload vehicle reentry dynamics. It is shown that the vehicle dynamics at parachute deployment are well within the design limit of the recovery system, thus ensuring successful payload recovery.

Aerodynamics of a Party Balloon

ERIC Educational Resources Information Center

Cross, Rod

2007-01-01

It is well-known that a party balloon can be made to fly erratically across a room, but it can also be used for quantitative measurements of other aspects of aerodynamics. Since a balloon is light and has a large surface area, even relatively weak aerodynamic forces can be readily demonstrated or measured in the classroom. Accurate measurements…

Aerodynamic design using numerical optimization

NASA Technical Reports Server (NTRS)

Murman, E. M.; Chapman, G. T.

1983-01-01

The procedure of using numerical optimization methods coupled with computational fluid dynamic (CFD) codes for the development of an aerodynamic design is examined. Several approaches that replace wind tunnel tests, develop pressure distributions and derive designs, or fulfill preset design criteria are presented. The method of Aerodynamic Design by Numerical Optimization (ADNO) is described and illustrated with examples.

Aerodynamic analysis of Pegasus - Computations vs reality

NASA Technical Reports Server (NTRS)

Mendenhall, Michael R.; Lesieutre, Daniel J.; Whittaker, C. H.; Curry, Robert E.; Moulton, Bryan

1993-01-01

Pegasus, a three-stage, air-launched, winged space booster was developed to provide fast and efficient commercial launch services for small satellites. The aerodynamic design and analysis of Pegasus was conducted without benefit of wind tunnel tests using only computational aerodynamic and fluid dynamic methods. Flight test data from the first two operational flights of Pegasus are now available, and they provide an opportunity to validate the accuracy of the predicted pre-flight aerodynamic characteristics. Comparisons of measured and predicted flight characteristics are presented and discussed. Results show that the computational methods provide reasonable aerodynamic design information with acceptable margins. Post-flight analyses illustrate certain areas in which improvements are desired.

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.

Nd:YAG Laser-Based Dual-Line Detection Rayleigh Scattering and Current Efforts on UV, Filtered Rayleigh Scattering

NASA Technical Reports Server (NTRS)

Otugen, M. Volkan; Popovic, Svetozar

1996-01-01

Ongoing research in Rayleigh scattering diagnostics for variable density low speed flow applications and for supersonic flow measurements are described. During the past several years, the focus has been on the development and use of a Nd:YAG-based Rayleigh scattering system with improved signal-to-noise characteristics and with applicability to complex, confined flows. This activity serves other research projects in the Aerodynamics Laboratory which require the non-contact, accurate, time-frozen measurement of gas density, pressure, and temperature (each separately), in a fairly wide dynamic range of each parameter. Recently, with the acquisition of a new seed-injected Nd:YAG laser, effort also has been directed to the development of a high-speed velocity probe based on a spectrally resolved Rayleigh scattering technique.

Establishing repeatable operation of a centrifugal compressor research facility for aerodynamic investigations

NASA Astrophysics Data System (ADS)

Dolan, Matthew Philip

The objective of this research has been to analyze the steady state performance of a new centrifugal compressor research facility. The CSTAR (Centrifugal STage for Aerodynamic Research) compressor has been designed to be placed as the last stage in an axial compressor and its performance in this flow regime was measured. Because the compressor was designed as a research vehicle, unique instrumentation throughout the flow path provides a detailed look at its steady state performance. Rakes at the inlet and deswirl section quantify the overall performance but other instrumentation is used to understand the component performance. Static pressure taps along the shroud, within the diffuser, and through the turn-to-axial show the static pressure rise. Additionally, rakes at the inlet and exit of diffuser also characterize the performance of the wedge diffuser and the impeller. Additionally, capacitance probes located at the knee and exducer of the impeller non-intrusively measure the size of the tip clearance during facility operation. An investigation into these measurements resulted in a standard procedure for in-situ calibration and installation to produce repeatable and accurate clearance measurements. Finally, the feasibility of future Laser Doppler Velocimetry measurements acquired through the shroud window was tested and was found to be achievable with the use of beam translators to ensure that measurement volumes are created after beam refraction through the windows. Inlet conditions of the facility have been investigated and fluctuations of the ambient conditions have been mitigated with a large settling chamber to ensure repeatable and stable operation. The current instrumentation was utilized to determine the compressor performance. Measurements of the steady performance parameters along with those of the internal flowfield are documented.

Preliminary Aerodynamic Investigation of Fan Rotor Blade Morphing

NASA Technical Reports Server (NTRS)

Tweedt, Daniel L.

2012-01-01

Various new technologies currently under development may enable controlled blade shape variability, or so-called blade morphing, to be practically employed in aircraft engine fans and compressors in the foreseeable future. The current study is a relatively brief, preliminary computational fluid dynamics investigation aimed at partially demonstrating and quantifying the aerodynamic potential of fan rotor blade morphing. The investigation is intended to provide information useful for near-term planning, as well as aerodynamic solution data sets that can be subsequently analyzed using advanced acoustic diagnostic tools, for the purpose of making fan noise comparisons. Two existing fan system models serve as baselines for the investigation: the Advanced Ducted Propulsor fan with a design tip speed of 806 ft/sec and a pressure ratio of 1.294, and the Source Diagnostic Test fan with a design tip speed of 1215 ft/sec and a pressure ratio of 1.470. Both are 22-in. sub-scale, low-noise research fan/nacelle models that have undergone extensive experimental testing in the 9- by 15-foot Low Speed Wind Tunnel at the NASA Glenn Research Center. The study, restricted to fan rotor blade morphing only, involves a fairly simple blade morphing technique. Specifically, spanwise-linear variations in rotor blade-section setting angle are applied to alter the blade shape; that is, the blade is linearly retwisted from hub to tip. Aerodynamic performance comparisons are made between morphed-blade and corresponding baseline configurations on the basis of equal fan system thrust, where rotor rotational speed for the morphed-blade fan is varied to change the thrust level for that configuration. The results of the investigation confirm that rotor blade morphing could be a useful technology, with the potential to enable significant improvements in fan aerodynamic performance. Even though the study is very limited in scope and confined to simple geometric perturbations of two existing fan

Calculation of subsonic and supersonic steady and unsteady aerodynamic forces using velocity potential aerodynamic elements

NASA Technical Reports Server (NTRS)

Haviland, J. K.; Yoo, Y. S.

1976-01-01

Expressions for calculation of subsonic and supersonic, steady and unsteady aerodynamic forces are derived, using the concept of aerodynamic elements applied to the downwash velocity potential method. Aerodynamic elements can be of arbitrary out of plane polygon shape, although numerical calculations are restricted to rectangular elements, and to the steady state case in the supersonic examples. It is suggested that the use of conforming, in place of rectangular elements, would give better results. Agreement with results for subsonic oscillating T tails is fair, but results do not converge as the number of collocation points is increased. This appears to be due to the form of expression used in the calculations. The methods derived are expected to facilitate automated flutter analysis on the computer. In particular, the aerodynamic element concept is consistent with finite element methods already used for structural analysis. The method is universal for the complete Mach number range, and, finally, the calculations can be arranged so that they do not have to be repeated completely for every reduced frequency.

Compendium of Unsteady Aerodynamic Measurements

DTIC Science & Technology

1982-08-01

O.N : R.A. (Directicn) Main Library 29 Ave iue de 14 Divisi L "emr 11.0. Box 25 9.2320 Cb4tillon sous llagipcua N-2007 Kjetlar GERMANY PORTUGAL Far...AGARD-R-702 IIN AGARI) REPORT No. 702 Compendium of Unstead Aerodynamic M easuremtents ~~~ Czppoved INV 4932ktaLthr71*!idi L , tISTh.BUTION AND...AVAILABILITY ON BACK COVER L 2/ AGARD-R-702 NORTH ATLANTIC TREATY ORGANIZATION ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT (ORGANISATION DU TRAITE

X-33 Aerodynamic and Aeroheating Computations for Wind Tunnel and Flight Conditions

NASA Technical Reports Server (NTRS)

Hollis, Brian R.; Thompson, Richard A.; Murphy, Kelly J.; Nowak, Robert J.; Riley, Christopher J.; Wood, William A.; Alter, Stephen J.; Prabhu, Ramadas K.

1999-01-01

This report provides an overview of hypersonic Computational Fluid Dynamics research conducted at the NASA Langley Research Center to support the Phase II development of the X-33 vehicle. The X-33, which is being developed by Lockheed-Martin in partnership with NASA, is an experimental Single-Stage-to-Orbit demonstrator that is intended to validate critical technologies for a full-scale Reusable Launch Vehicle. As part of the development of the X-33, CFD codes have been used to predict the aerodynamic and aeroheating characteristics of the vehicle. Laminar and turbulent predictions were generated for the X 33 vehicle using two finite- volume, Navier-Stokes solvers. Inviscid solutions were also generated with an Euler code. Computations were performed for Mach numbers of 4.0 to 10.0 at angles-of-attack from 10 deg to 48 deg with body flap deflections of 0, 10 and 20 deg. Comparisons between predictions and wind tunnel aerodynamic and aeroheating data are presented in this paper. Aeroheating and aerodynamic predictions for flight conditions are also presented.

The aerodynamic challenges of the design and development of the space shuttle orbiter

NASA Technical Reports Server (NTRS)

Young, J. C.; Underwood, J. M.; Hillje, E. R.; Whitnah, A. M.; Romere, P. O.; Gamble, J. D.; Roberts, B. B.; Ware, G. M.; Scallion, W. I.; Spencer, B., Jr.

1985-01-01

The major aerodynamic design challenge at the beginning of the United States Space Transportation System (STS) research and development phase was to design a vehicle that would fly as a spacecraft during early entry and as an aircraft during the final phase of entry. The design was further complicated because the envisioned vehicle was statically unstable during a portion of the aircraft mode of operation. The second challenge was the development of preflight aerodynamic predictions with an accuracy consistent with conducting a manned flight on the initial orbital flight. A brief history of the early contractual studies is presented highlighting the technical results and management decisions influencing the aerodynamic challenges. The configuration evolution and the development of preflight aerodynamic predictions will be reviewed. The results from the first four test flights shows excellent agreement with the preflight aerodynamic predictions over the majority of the flight regimes. The only regimes showing significant disagreement is confined primarily to early entry, where prediction of the basic vehicle trim and the influence of the reaction control system jets on the flow field were found to be deficient. Postflight results are analyzed to explain these prediction deficiencies.

Aerodynamic seal assemblies for turbo-machinery

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

Bidkar, Rahul Anil; Wolfe, Christopher; Fang, Biao

2015-09-29

The present application provides an aerodynamic seal assembly for use with a turbo-machine. The aerodynamic seal assembly may include a number of springs, a shoe connected to the springs, and a secondary seal positioned about the springs and the shoe.

Korea University Joins the International Efforts in Clinical Proteogenomics Cancer Research | Office of Cancer Clinical Proteomics Research

Cancer.gov

The National Cancer Institute's (NCI) Office of Cancer Clinical Proteomics Research, part of the National Institutes of Health, and Korea University (KU) located in The Republic of Korea have signed a Memorandum of Understanding (MOU) in clinical proteogenomics cancer research. The MOU between NCI and KU represents the twenty-ninth institution and eleventh country to join the continued effort of the International Cancer Proteogenome Consortium (ICPC), an effort catalyzed through the vision of the 47th Vice President of the United States Joseph R. Biden, Jr. and the Cancer Moonshot.

Aerodynamics of electrically driven freight pipeline system

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

Lundgren, T.S.; Zhao, Y.

2000-06-01

This paper examines the aerodynamic characteristics of a freight pipeline system in which freight capsules are individually propelled by electrical motors. The fundamental difference between this system and the more extensively studied pneumatic capsule pipeline is the different role played by aerodynamic forces. In a driven system the propelled capsules are resisted by aerodynamic forces and, in reaction, pump air through the tube. In contrast, in a pneumatically propelled system external blowers pump air through the tubes, and this provides the thrust for the capsules. An incompressible transient analysis is developed to study the aerodynamics of multiple capsules in amore » cross-linked two-bore pipeline. An aerodynamic friction coefficient is used as a cost parameter to compare the effects of capsule blockage and headway and to assess the merits of adits and vents. The authors conclude that optimum efficiency for off-design operation is obtained with long platoons of capsules in vented or adit connected tubes.« less

Global Design Optimization for Aerodynamics and Rocket Propulsion Components

NASA Technical Reports Server (NTRS)

Shyy, Wei; Papila, Nilay; Vaidyanathan, Rajkumar; Tucker, Kevin; Turner, James E. (Technical Monitor)

2000-01-01

Modern computational and experimental tools for aerodynamics and propulsion applications have matured to a stage where they can provide substantial insight into engineering processes involving fluid flows, and can be fruitfully utilized to help improve the design of practical devices. In particular, rapid and continuous development in aerospace engineering demands that new design concepts be regularly proposed to meet goals for increased performance, robustness and safety while concurrently decreasing cost. To date, the majority of the effort in design optimization of fluid dynamics has relied on gradient-based search algorithms. Global optimization methods can utilize the information collected from various sources and by different tools. These methods offer multi-criterion optimization, handle the existence of multiple design points and trade-offs via insight into the entire design space, can easily perform tasks in parallel, and are often effective in filtering the noise intrinsic to numerical and experimental data. However, a successful application of the global optimization method needs to address issues related to data requirements with an increase in the number of design variables, and methods for predicting the model performance. In this article, we review recent progress made in establishing suitable global optimization techniques employing neural network and polynomial-based response surface methodologies. Issues addressed include techniques for construction of the response surface, design of experiment techniques for supplying information in an economical manner, optimization procedures and multi-level techniques, and assessment of relative performance between polynomials and neural networks. Examples drawn from wing aerodynamics, turbulent diffuser flows, gas-gas injectors, and supersonic turbines are employed to help demonstrate the issues involved in an engineering design context. Both the usefulness of the existing knowledge to aid current design

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.

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.

Integrated Computational System for Aerodynamic Steering and Visualization

NASA Technical Reports Server (NTRS)

Hesselink, Lambertus

1999-01-01

In February of 1994, an effort from the Fluid Dynamics and Information Sciences Divisions at NASA Ames Research Center with McDonnel Douglas Aerospace Company and Stanford University was initiated to develop, demonstrate, validate and disseminate automated software for numerical aerodynamic simulation. The goal of the initiative was to develop a tri-discipline approach encompassing CFD, Intelligent Systems, and Automated Flow Feature Recognition to improve the utility of CFD in the design cycle. This approach would then be represented through an intelligent computational system which could accept an engineer's definition of a problem and construct an optimal and reliable CFD solution. Stanford University's role focused on developing technologies that advance visualization capabilities for analysis of CFD data, extract specific flow features useful for the design process, and compare CFD data with experimental data. During the years 1995-1997, Stanford University focused on developing techniques in the area of tensor visualization and flow feature extraction. Software libraries were created enabling feature extraction and exploration of tensor fields. As a proof of concept, a prototype system called the Integrated Computational System (ICS) was developed to demonstrate CFD design cycle. The current research effort focuses on finding a quantitative comparison of general vector fields based on topological features. Since the method relies on topological information, grid matching and vector alignment is not needed in the comparison. This is often a problem with many data comparison techniques. In addition, since only topology based information is stored and compared for each field, there is a significant compression of information that enables large databases to be quickly searched. This report will (1) briefly review the technologies developed during 1995-1997 (2) describe current technologies in the area of comparison techniques, (4) describe the theory of our new

Aerodynamic levitation, supercooled liquids and glass formation

DOE PAGES

Benmore, C. J.; Weber, J. K. R.

2017-05-04

Containerless processing or ‘levitation’ is a valuable tool for the synthesis and characterization of materials, particularly at extreme temperatures and under non-equilibrium conditions. The method enables formation of novel glasses, amorphous phases, and metastable crystalline forms that are not easily accessed when nucleation and growth can readily occur at a container interface. Removing the container enables the use of a wide variety of process atmospheres to modify a materials structure and properties. In the past decade levitation methods, including acoustic, aerodynamic, electromagnetic, and electrostatic, have become well established sample environments at X-ray synchrotron and neutron sources. This article briefly reviewsmore » the methods and then focuses on the application of aerodynamic levitation to synthesize and study new materials. This is presented in conjunction with non-contact probes used to investigate the atomic structure and to measure the properties of materials at extreme temperatures. The use of aerodynamic levitation in research using small and wide-angle X-ray diffraction, XANES, and neutron scattering are discussed in the context of technique development. The use of the containerless methods to investigate thermophysical properties is also considered. We argue that structural motifs and in the liquid state can potentially lead to the fabrication of materials, whose properties would differ substantially from their well known crystalline forms.« less

Statistical Analysis of the Uncertainty in Pre-Flight Aerodynamic Database of a Hypersonic Vehicle

NASA Astrophysics Data System (ADS)

Huh, Lynn

The objective of the present research was to develop a new method to derive the aerodynamic coefficients and the associated uncertainties for flight vehicles via post- flight inertial navigation analysis using data from the inertial measurement unit. Statistical estimates of vehicle state and aerodynamic coefficients are derived using Monte Carlo simulation. Trajectory reconstruction using the inertial navigation system (INS) is a simple and well used method. However, deriving realistic uncertainties in the reconstructed state and any associated parameters is not so straight forward. Extended Kalman filters, batch minimum variance estimation and other approaches have been used. However, these methods generally depend on assumed physical models, assumed statistical distributions (usually Gaussian) or have convergence issues for non-linear problems. The approach here assumes no physical models, is applicable to any statistical distribution, and does not have any convergence issues. The new approach obtains the statistics directly from a sufficient number of Monte Carlo samples using only the generally well known gyro and accelerometer specifications and could be applied to the systems of non-linear form and non-Gaussian distribution. When redundant data are available, the set of Monte Carlo simulations are constrained to satisfy the redundant data within the uncertainties specified for the additional data. The proposed method was applied to validate the uncertainty in the pre-flight aerodynamic database of the X-43A Hyper-X research vehicle. In addition to gyro and acceleration data, the actual flight data include redundant measurements of position and velocity from the global positioning system (GPS). The criteria derived from the blend of the GPS and INS accuracy was used to select valid trajectories for statistical analysis. The aerodynamic coefficients were derived from the selected trajectories by either direct extraction method based on the equations in

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.

Nonlinear aerodynamic wing design

NASA Technical Reports Server (NTRS)

Bonner, Ellwood

1985-01-01

The applicability of new nonlinear theoretical techniques is demonstrated for supersonic wing design. The new technology was utilized to define outboard panels for an existing advanced tactical fighter model. Mach 1.6 maneuver point design and multi-operating point compromise surfaces were developed and tested. High aerodynamic efficiency was achieved at the design conditions. A corollary result was that only modest supersonic penalties were incurred to meet multiple aerodynamic requirements. The nonlinear potential analysis of a practical configuration arrangement correlated well with experimental data.

Research, public policymaking, and knowledge-translation processes: Canadian efforts to build bridges.

PubMed

Lavis, John N

2006-01-01

Public policymakers must contend with a particular set of institutional arrangements that govern what can be done to address any given issue, pressure from a variety of interest groups about what they would like to see done to address any given issue, and a range of ideas (including research evidence) about how best to address any given issue. Rarely do processes exist that can get optimally packaged high-quality and high-relevance research evidence into the hands of public policymakers when they most need it, which is often in hours and days, not months and years. In Canada, a variety of efforts have been undertaken to address the factors that have been found to increase the prospects for research use, including the production of systematic reviews that meet the shorter term (but not urgent) needs of public policymakers and encouraging partnerships between researchers and policymakers that allow for their interaction around the tasks of asking and answering relevant questions. Much less progress has been made in making available research evidence to inform the urgent needs of public policymakers and in addressing attitudinal barriers and capacity limitations. In the future, knowledge-translation processes, particularly push efforts and efforts to facilitate user pull, should be undertaken on a sufficiently large scale and with a sufficiently rigorous evaluation so that robust conclusions can be drawn about their effectiveness.

Numerical Study of Steady and Unsteady Canard-Wing-Body Aerodynamics

NASA Technical Reports Server (NTRS)

Eugene, L. Tu

1996-01-01

The use of canards in advanced aircraft for control and improved aerodynamic performance is a topic of continued interest and research. In addition to providing maneuver control and trim, the influence of canards on wing aerodynamics can often result in increased maximum lift and decreased trim drag. In many canard-configured aircraft, the main benefits of canards are realized during maneuver or other dynamic conditions. Therefore, the detailed study and understanding of canards requires the accurate prediction of the non-linear unsteady aerodynamics of such configurations. For close-coupled canards, the unsteady aerodynamic performance associated with the canard-wing interaction is of particular interest. The presence of a canard in close proximity to the wing results in a highly coupled canard-wing aerodynamic flowfield which can include downwash/upwash effects, vortex-vortex interactions and vortex-surface interactions. For unsteady conditions, these complexities of the canard-wing flowfield are further increased. The development and integration of advanced computational technologies provide for the time-accurate Navier-Stokes simulations of the steady and unsteady canard-wing-body flox,fields. Simulation, are performed for non-linear flight regimes at transonic Mach numbers and for a wide range of angles of attack. For the static configurations, the effects of canard positioning and fixed deflection angles on aerodynamic performance and canard-wing vortex interaction are considered. For non-static configurations, the analyses of the canard-wing body flowfield includes the unsteady aerodynamics associated with pitch-up ramp and pitch oscillatory motions of the entire geometry. The unsteady flowfield associated with moving canards which are typically used as primary control surfaces are considered as well. The steady and unsteady effects of the canard on surface pressure integrated forces and moments, and canard-wing vortex interaction are presented in detail

An unstructured-grid software system for solving complex aerodynamic problems

NASA Technical Reports Server (NTRS)

Frink, Neal T.; Pirzadeh, Shahyar; Parikh, Paresh

1995-01-01

A coordinated effort has been underway over the past four years to elevate unstructured-grid methodology to a mature level. The goal of this endeavor is to provide a validated capability to non-expert users for performing rapid aerodynamic analysis and design of complex configurations. The Euler component of the system is well developed, and is impacting a broad spectrum of engineering needs with capabilities such as rapid grid generation and inviscid flow analysis, inverse design, interactive boundary layers, and propulsion effects. Progress is also being made in the more tenuous Navier-Stokes component of the system. A robust grid generator is under development for constructing quality thin-layer tetrahedral grids, along with a companion Navier-Stokes flow solver. This paper presents an overview of this effort, along with a perspective on the present and future status of the methodology.

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.

Changes in federal agencies panel: human dimensions research and ecosystem management: policy and research implications for recreation research efforts

Treesearch

Alan Ewert

1995-01-01

With an increased emphasis being placed on ecosystem management, the importance of Human Dimension Research (HDR) efforts in management and policy formulation are becoming more important. Developing an understanding of the type of management questions and policy needs that can be addressed by human dimension research is becoming increasingly important and timely. This...

[Effort-reward imbalance at work and depression: current research evidence].

PubMed

Siegrist, J

2013-01-01

In view of highly prevalent stressful conditions in modern working life, in particular increasing work pressure and job insecurity, it is of interest to know whether specific constellations of an adverse psychosocial work environment increase the risk of depressive disorder among employed people. This contribution gives a short overview of current research evidence based on an internationally established work stress model of effort-reward imbalance. Taken together, results from seven prospective epidemiological investigations demonstrate a two-fold elevated relative risk of incident depressive disorder over a mean observation period of 2.7 years among exposed versus non-exposed employees. Additional findings from experimental and quasi-experimental studies point to robust associations of effort-reward imbalance at work with proinflammatory cytokines and markers of reduced immune competence. These latter markers may indicate potential psychobiological pathways. In conclusion, incorporating this new knowledge into medical treatment and preventive efforts seems well justified.

Some lessons from NACA/NASA aerodynamic studies following World War II

NASA Technical Reports Server (NTRS)

Spearman, M. L.

1983-01-01

An historical account is presented of the new departures in aerodynamic research conducted by NACA, and subsequently NASA, as a result of novel aircraft technologies and operational regimes encountered in the course of the Second World War. The invention and initial development of the turbojet engine furnished the basis for a new speed/altitude regime in which numerous aerodynamic design problems arose. These included compressibility effects near the speed of sound, with attendant lift/drag efficiency reductions and longitudinal stability enhancements that were accompanied by a directional stability reduction. Major research initiatives were mounted in the investigation of swept, delta, trapezoidal and variable sweep wing configurations, sometimes conducted through flight testing of the 'X-series' aircraft. Attention is also given to the development of the first generation of supersonic fighter aircraft.

Vertical Landing Aerodynamics of Reusable Rocket Vehicle

NASA Astrophysics Data System (ADS)

Nonaka, Satoshi; Nishida, Hiroyuki; Kato, Hiroyuki; Ogawa, Hiroyuki; Inatani, Yoshifumi

The aerodynamic characteristics of a vertical landing rocket are affected by its engine plume in the landing phase. The influences of interaction of the engine plume with the freestream around the vehicle on the aerodynamic characteristics are studied experimentally aiming to realize safe landing of the vertical landing rocket. The aerodynamic forces and surface pressure distributions are measured using a scaled model of a reusable rocket vehicle in low-speed wind tunnels. The flow field around the vehicle model is visualized using the particle image velocimetry (PIV) method. Results show that the aerodynamic characteristics, such as the drag force and pitching moment, are strongly affected by the change in the base pressure distributions and reattachment of a separation flow around the vehicle.

Status, Plans, and Initial Results for ARES 1 Crew Launch Vehicle Aerodynamics

NASA Technical Reports Server (NTRS)

Huebner, Lawrence D.; Haynes, Davy A.; Taylor, Terry L.; Hall, Robert M.; Pamadi, Bandu N.; Seaford, C. Mark

2006-01-01

Following the completion of NASA's Exploration Systems Architecture Study in August 2004 for the NASA Exploration Systems Mission Directorate (ESMD), the Exploration Launch Office at the NASA Marshall Space Flight Center was assigned project management responsibilities for the design and development of the first vehicle in the architecture, the Ares I Crew Launch Vehicle (CLV), which will be used to launch astronauts to low earth orbit and rendezvous with either the International Space Station or the ESMD s earth departure stage for lunar or other future missions beyond low Earth orbit. The primary elements of the Ares I CLV project are the first stage, the upper stage, the upper stage engine, and vehicle integration. Within vehicle integration is an effort in integrated design and analysis which is comprised of a number of technical disciplines needed to support vehicle design and development. One of the important disciplines throughout the life of the project is aerodynamics. This paper will present the status, plans, and initial results of Ares I CLV aerodynamics as the project was preparing for the Ares I CLV Systems Requirements Review. Following a discussion of the specific interactions with other technical panels and a status of the current activities, the plans for aerodynamic support of the Ares I CLV until the initial crewed flights will be presented.

Variable-Speed Power-Turbine Research at Glenn Research Center

NASA Technical Reports Server (NTRS)

Welch, Gerard E.; McVetta, Ashlie B.; Stevens, Mark A.; Howard, Samuel A.; Giel, Paul W.; Ameri, Ali, A.; To, Waiming; Skoch, Gary J.; Thurman, Douglas R.

2012-01-01

The main rotors of the NASA Large Civil Tilt-Rotor (LCTR) notional vehicle operate over a wide speed-range, from 100 percent at takeoff to 54 percent at cruise. The variable-speed power turbine (VSPT) offers one approach by which to effect this speed variation. VSPT aerodynamics challenges include high work factors at cruise, wide (40 to 60 ) incidence-angle variations in blade and vane rows over the speed range, and operation at low Reynolds numbers. Rotordynamics challenges include potential responsiveness to shaft modes within the 50 percent VSPT speed-range. A research effort underway at NASA Glenn Research Center, intended to address these key aerodynamic and rotordynamic challenges, is described. Conceptual design and 3-D multistage RANS and URANS analyses, conducted internally and under contract, provide expected VSPT sizing, stage-count, performance and operability information, and maps for system studies. Initial steps toward experimental testing of incidence-tolerant blading in a transonic linear cascade are described, and progress toward development/improvement of a simulation capability for multistage turbines with low Reynolds number transitional flow is summarized. Preliminary rotordynamics analyses indicate that viable concept engines with 50 percent VSPT shaft-speed range. Assessments of potential paths toward VSPT component-level testing are summarized.

Aerodynamics model for a generic ASTOVL lift-fan aircraft

NASA Technical Reports Server (NTRS)

Birckelbaw, Lourdes G.; Mcneil, Walter E.; Wardwell, Douglas A.

1995-01-01

This report describes the aerodynamics model used in a simulation model of an advanced short takeoff and vertical landing (ASTOVL) lift-fan fighter aircraft. The simulation model was developed for use in piloted evaluations of transition and hover flight regimes, so that only low speed (M approximately 0.2) aerodynamics are included in the mathematical model. The aerodynamic model includes the power-off aerodynamic forces and moments and the propulsion system induced aerodynamic effects, including ground effects. The power-off aerodynamics data were generated using the U.S. Air Force Stability and Control Digital DATCOM program and a NASA Ames in-house graphics program called VORVIEW which allows the user to easily analyze arbitrary conceptual aircraft configurations using the VORLAX program. The jet-induced data were generated using the prediction methods of R. E. Kuhn et al., as referenced in this report.

Validation of 3-D Ice Accretion Measurement Methodology for Experimental Aerodynamic Simulation

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Addy, Harold E., Jr.; Lee, Sam; Monastero, Marianne C.

2015-01-01

Determining the adverse aerodynamic effects due to ice accretion often relies on dry-air wind-tunnel testing of artificial, or simulated, ice shapes. Recent developments in ice-accretion documentation methods have yielded a laser-scanning capability that can measure highly three-dimensional (3-D) features of ice accreted in icing wind tunnels. The objective of this paper was to evaluate the aerodynamic accuracy of ice-accretion simulations generated from laser-scan data. Ice-accretion tests were conducted in the NASA Icing Research Tunnel using an 18-in. chord, two-dimensional (2-D) straight wing with NACA 23012 airfoil section. For six ice-accretion cases, a 3-D laser scan was performed to document the ice geometry prior to the molding process. Aerodynamic performance testing was conducted at the University of Illinois low-speed wind tunnel at a Reynolds number of 1.8 × 10(exp 6) and a Mach number of 0.18 with an 18-in. chord NACA 23012 airfoil model that was designed to accommodate the artificial ice shapes. The ice-accretion molds were used to fabricate one set of artificial ice shapes from polyurethane castings. The laser-scan data were used to fabricate another set of artificial ice shapes using rapid prototype manufacturing such as stereolithography. The iced-airfoil results with both sets of artificial ice shapes were compared to evaluate the aerodynamic simulation accuracy of the laser-scan data. For five of the six ice-accretion cases, there was excellent agreement in the iced-airfoil aerodynamic performance between the casting and laser-scan based simulations. For example, typical differences in iced-airfoil maximum lift coefficient were less than 3 percent with corresponding differences in stall angle of approximately 1 deg or less. The aerodynamic simulation accuracy reported in this paper has demonstrated the combined accuracy of the laser-scan and rapid-prototype manufacturing approach to simulating ice accretion for a NACA 23012 airfoil. For several

Validation of 3-D Ice Accretion Measurement Methodology for Experimental Aerodynamic Simulation

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Addy, Harold E., Jr.; Lee, Sam; Monastero, Marianne C.

2014-01-01

Determining the adverse aerodynamic effects due to ice accretion often relies on dry-air wind-tunnel testing of artificial, or simulated, ice shapes. Recent developments in ice accretion documentation methods have yielded a laser-scanning capability that can measure highly three-dimensional features of ice accreted in icing wind tunnels. The objective of this paper was to evaluate the aerodynamic accuracy of ice-accretion simulations generated from laser-scan data. Ice-accretion tests were conducted in the NASA Icing Research Tunnel using an 18-inch chord, 2-D straight wing with NACA 23012 airfoil section. For six ice accretion cases, a 3-D laser scan was performed to document the ice geometry prior to the molding process. Aerodynamic performance testing was conducted at the University of Illinois low-speed wind tunnel at a Reynolds number of 1.8 x 10(exp 6) and a Mach number of 0.18 with an 18-inch chord NACA 23012 airfoil model that was designed to accommodate the artificial ice shapes. The ice-accretion molds were used to fabricate one set of artificial ice shapes from polyurethane castings. The laser-scan data were used to fabricate another set of artificial ice shapes using rapid prototype manufacturing such as stereolithography. The iced-airfoil results with both sets of artificial ice shapes were compared to evaluate the aerodynamic simulation accuracy of the laser-scan data. For four of the six ice-accretion cases, there was excellent agreement in the iced-airfoil aerodynamic performance between the casting and laser-scan based simulations. For example, typical differences in iced-airfoil maximum lift coefficient were less than 3% with corresponding differences in stall angle of approximately one degree or less. The aerodynamic simulation accuracy reported in this paper has demonstrated the combined accuracy of the laser-scan and rapid-prototype manufacturing approach to simulating ice accretion for a NACA 23012 airfoil. For several of the ice

Aerodynamic measurement techniques. [laser based diagnostic techniques

NASA Technical Reports Server (NTRS)

Hunter, W. W., Jr.

1976-01-01

Laser characteristics of intensity, monochromatic, spatial coherence, and temporal coherence were developed to advance laser based diagnostic techniques for aerodynamic related research. Two broad categories of visualization and optical measurements were considered, and three techniques received significant attention. These are holography, laser velocimetry, and Raman scattering. Examples of the quantitative laser velocimeter and Raman scattering measurements of velocity, temperature, and density indicated the potential of these nonintrusive techniques.

Configuration development study of the OSU 1 hypersonic research vehicle

NASA Technical Reports Server (NTRS)

Stein, Matthew D.; Frankhauser, Chris; Zee, Warner; Kosanchick, Melvin, III; Nelson, Nick; Hunt, William

1993-01-01

In an effort to insure the future development of hypersonic cruise aircraft, the possible vehicle configurations were examined to develop a single-stage-to-orbit hypersonic research vehicle (HRV). Based on the needs of hypersonic research and development, the mission goals and requirements are determined. A body type is chosen. Three modes of propulsion and two liquid rocket fuels are compared, followed by the optimization of the body configuration through aerodynamic, weight, and trajectory studies. A cost analysis is included.

Shuttle Orbiter Contingency Abort Aerodynamics: Real-Gas Effects and High Angles of Attack

NASA Technical Reports Server (NTRS)

Prabhu, Dinesh K.; Papadopoulos, Periklis E.; Davies, Carol B.; Wright, Michael J.; McDaniel, Ryan D.; Venkatapathy, Ethiraj; Wercinski, Paul F.

2005-01-01

An important element of the Space Shuttle Orbiter safety improvement plan is the improved understanding of its aerodynamic performance so as to minimize the "black zones" in the contingency abort trajectories [1]. These zones are regions in the launch trajectory where it is predicted that, due to vehicle limitations, the Orbiter will be unable to return to the launch site in a two or three engine-out scenario. Reduction of these zones requires accurate knowledge of the aerodynamic forces and moments to better assess the structural capability of the vehicle. An interesting aspect of the contingency abort trajectories is that the Orbiter would need to achieve angles of attack as high as 60deg. Such steep attitudes are much higher than those for a nominal flight trajectory. The Orbiter is currently flight certified only up to an angle of attack of 44deg at high Mach numbers and has never flown at angles of attack larger than this limit. Contingency abort trajectories are generated using the data in the Space Shuttle Operational Aerodynamic Data Book (OADB) [2]. The OADB, a detailed document of the aerodynamic environment of the current Orbiter, is primarily based on wind-tunnel measurements (over a wide Mach number and angle-of-attack range) extrapolated to flight conditions using available theories and correlations, and updated with flight data where available. For nominal flight conditions, i.e., angles of attack of less than 45deg, the fidelity of the OADB is excellent due to the availability of flight data. However, at the off-nominal conditions, such as would be encountered on contingency abort trajectories, the fidelity of the OADB is less certain. The primary aims of a recent collaborative effort (completed in the year 2001) between NASA and Boeing were to determine: 1) accurate distributions of pressure and shear loads on the Orbiter at select points in the contingency abort trajectory space; and 2) integrated aerodynamic forces and moments for the entire

Sensor Systems Collect Critical Aerodynamics Data

NASA Technical Reports Server (NTRS)

2010-01-01

With the support of Small Business Innovation Research (SBIR) contracts with Dryden Flight Research Center, Tao of Systems Integration Inc. developed sensors and other components that will ultimately form a first-of-its-kind, closed-loop system for detecting, measuring, and controlling aerodynamic forces and moments in flight. The Hampton, Virginia-based company commercialized three of the four planned components, which provide sensing solutions for customers such as Boeing, General Electric, and BMW and are used for applications such as improving wind turbine operation and optimizing air flow from air conditioning systems. The completed system may one day enable flexible-wing aircraft with flight capabilities like those of birds.

Wing motion transformation to evaluate aerodynamic coupling in flapping wing flight.

PubMed

Faruque, Imraan A; Humbert, J Sean

2014-12-21

Whether the remarkable flight performance of insects is because the animals leverage inherent physics at this scale or because they employ specialized neural feedback mechanisms is an active research question. In this study, an empirically derived aerodynamics model is used with a transformation involving a delay and a rotation to identify a class of kinematics that provide favorable roll-yaw coupling. The transformation is also used to transform both synthetic and experimentally measured wing motions onto the manifold representing proverse yaw and to quantify the degree to which freely flying insects make use of passive aerodynamic mechanisms to provide proverse roll-yaw turn coordination. The transformation indicates that recorded insect kinematics do act to provide proverse yaw for a variety of maneuvers. This finding suggests that passive aerodynamic mechanisms can act to reduce the neural feedback demands of an insect׳s flight control strategy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Review of Cranked-Arrow Wing Aerodynamics Project: Its International Aeronautical Community Role

NASA Technical Reports Server (NTRS)

Lamar, John E.; Obara, Clifford J.

2007-01-01

This paper provides a brief history of the F-16XL-1 aircraft, its role in the High Speed Research (HSR) program and how it was morphed into the Cranked Arrow Wing Aerodynamics Project (CAWAP). Various flight, wind-tunnel and Computational Fluid Dynamics (CFD) data sets were generated during the CAWAP. These unique and open flight datasets for surface pressures, boundary-layer profiles and skinfriction distributions, along with surface flow data, are described and sample data comparisons given. This is followed by a description of how the project became internationalized to be known as Cranked Arrow Wing Aerodynamics Project International (CAWAPI) and is concluded by an introduction to the results of a 4 year CFD predictive study of data collected at flight conditions by participating researchers.

System Dynamic Analysis of a Wind Tunnel Model with Applications to Improve Aerodynamic Data Quality

NASA Technical Reports Server (NTRS)

Buehrle, Ralph David

1997-01-01

The research investigates the effect of wind tunnel model system dynamics on measured aerodynamic data. During wind tunnel tests designed to obtain lift and drag data, the required aerodynamic measurements are the steady-state balance forces and moments, pressures, and model attitude. However, the wind tunnel model system can be subjected to unsteady aerodynamic and inertial loads which result in oscillatory translations and angular rotations. The steady-state force balance and inertial model attitude measurements are obtained by filtering and averaging data taken during conditions of high model vibrations. The main goals of this research are to characterize the effects of model system dynamics on the measured steady-state aerodynamic data and develop a correction technique to compensate for dynamically induced errors. Equations of motion are formulated for the dynamic response of the model system subjected to arbitrary aerodynamic and inertial inputs. The resulting modal model is examined to study the effects of the model system dynamic response on the aerodynamic data. In particular, the equations of motion are used to describe the effect of dynamics on the inertial model attitude, or angle of attack, measurement system that is used routinely at the NASA Langley Research Center and other wind tunnel facilities throughout the world. This activity was prompted by the inertial model attitude sensor response observed during high levels of model vibration while testing in the National Transonic Facility at the NASA Langley Research Center. The inertial attitude sensor cannot distinguish between the gravitational acceleration and centrifugal accelerations associated with wind tunnel model system vibration, which results in a model attitude measurement bias error. Bias errors over an order of magnitude greater than the required device accuracy were found in the inertial model attitude measurements during dynamic testing of two model systems. Based on a theoretical modal

Energy Harvesting from Aerodynamic Instabilities: Current prospect and Future Trends

NASA Astrophysics Data System (ADS)

Bashir, M.; Rajendran, P.; Khan, S. A.

2018-01-01

This paper evaluates the layout and advancement of energy harvesting based on aerodynamic instabilities of an aircraft. Vibration and thermoelectric energy harvesters are substantiated as most suitable alternative low-power sources for aerospace applications. Furthermore, the facility associated with the aircraft applications in harvesting the mechanical vibrations and converting it to electric energy has fascinated the researchers. These devices are designed as an alternative to a battery-based solution especially for small aircrafts, wireless structural health monitoring for aircraft systems, and harvester plates employed in UAVs to enhance the endurance and operational flight missions. We will emphasize on various sources of energy harvesting that are designed to come from aerodynamic flow-induced vibrations, specific attention is then given at those technologies that may offer, today or in the near future, a potential benefit to reduce both the cost and emissions of the aviation industry. The advancements achieved in the energy harvesting based on aerodynamic instabilities show very good scope for many piezoelectric harvesters in the field of aerospace, specifically green aviation technology in the future.

Analysis of Asymmetric Aircraft Aerodynamics Due to an Experimental Wing Glove

NASA Technical Reports Server (NTRS)

Hartshorn, Fletcher

2011-01-01

Aerodynamic computational fluid dynamics analysis of a wing glove attached to one wing of a business jet is presented and discussed. A wing glove placed on only one wing will produce asymmetric aerodynamic effects that will result in overall changes in the forces and moments acting on the aircraft. These changes, referred to as deltas, need to be determined and quantified to ensure that the wing glove does not have a significant effect on the aircraft flight characteristics. TRANAIR (Calmar Research Corporation, Cato, New York), a nonlinear full potential solver, and Star-CCM+ (CD-adapco, Melville, New York), a finite volume full Reynolds-averaged Navier-Stokes computational fluid dynamics solver, are used to analyze a full aircraft with and without the glove at a variety of flight conditions, aircraft configurations, and angles of attack and sideslip. Changes in the aircraft lift, drag, and side force along with roll, pitch, and yaw are presented. Span lift and moment distributions are also presented for a more detailed look at the effects of the glove on the aircraft. Aerodynamic flow phenomena due to the addition of the glove are discussed. Results show that the glove produces only small changes in the aerodynamic forces and moments acting on the aircraft, most of which are insignificant.

Vortex lattice prediction of subsonic aerodynamics of hypersonic vehicle concepts

NASA Technical Reports Server (NTRS)

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

1977-01-01

The vortex lattice method introduced by Lamar and Gloss (1975) was applied to the prediction of subsonic aerodynamic characteristics of hypersonic body-wing configurations. The reliability of the method was assessed through comparison of the calculated and observed aerodynamic performances of two National Hypersonic Flight Research Facility craft at Mach 0.2. The investigation indicated that a vortex lattice model involving 120 or more panel elements can give good results for the lift and induced drag coefficients of the craft, as well as for the pitching moment at angles of attack below 10 to 15 deg. Automated processes for calculating the local slopes of mean-camber surfaces may also render the method suitable for use in preliminary design phases.

An experimental investigation of the aerodynamics and cooling of a horizontally-opposed air-cooled aircraft engine installation

NASA Technical Reports Server (NTRS)

Miley, S. J.; Cross, E. J., Jr.; Owens, J. K.; Lawrence, D. L.

1981-01-01

A flight-test based research program was performed to investigate the aerodynamics and cooling of a horizontally-opposed engine installation. Specific areas investigated were the internal aerodynamics and cooling mechanics of the installation, inlet aerodynamics, and exit aerodynamics. The applicable theory and current state of the art are discussed for each area. Flight-test and ground-test techniques for the development of the cooling installation and the solution of cooling problems are presented. The results show that much of the internal aerodynamics and cooling technology developed for radial engines are applicable to horizontally opposed engines. Correlation is established between engine manufacturer's cooling design data and flight measurements of the particular installation. Also, a flight-test method for the development of cooling requirements in terms of easily measurable parameters is presented. The impact of inlet and exit design on cooling and cooling drag is shown to be of major significance.

Basic aerodynamic research facility for comparative studies of flow diagnostic techniques

NASA Technical Reports Server (NTRS)

Jones, Gregory S.; Gartrell, Luther R.; Stainback, P. Calvin

1987-01-01

Current flow diagnostic research efforts are focusing on higher order flow field data bases, such as those generated by laser velocimetry (LV), hot-wire anemometry, and multi-hole pressure probes. Recent low-speed comparisons of results obtained with LV and hot wires have revealed strengths and weaknesses of each instrument. A seeding study will be initiated to determine particulate tracking ability.

Scramjet exhaust simulation technique for hypersonic aircraft nozzle design and aerodynamic tests

NASA Technical Reports Server (NTRS)

Hunt, J. L.; Talcott, N. A., Jr.; Cubbage, J. M.

1977-01-01

Current design philosophy for scramjet-powered hypersonic aircraft results in configurations with the entire lower fuselage surface utilized as part of the propulsion system. The lower aft-end of the vehicle acts as a high expansion ratio nozzle. Not only must the external nozzle be designed to extract the maximum possible thrust force from the high energy flow at the combustor exit, but the forces produced by the nozzle must be aligned such that they do not unduly affect aerodynamic balance. The strong coupling between the propulsion system and aerodynamics of the aircraft makes imperative at least a partial simulation of the inlet, exhaust, and external flows of the hydrogen-burning scramjet in conventional facilities for both nozzle formulation and aerodynamic-force data acquisition. Aerodynamic testing methods offer no contemporary approach for such vehicle design requirements. NASA-Langley has pursued an extensive scramjet/airframe integration R&D program for several years and has recently developed a promising technique for simulation of the scramjet exhaust flow for hypersonic aircraft. Current results of the research program to develop a scramjet flow simulation technique through the use of substitute gas blends are described in this paper.

Supersonic aerodynamics of delta wings

NASA Technical Reports Server (NTRS)

Wood, Richard M.

1988-01-01

Through the empirical correlation of experimental data and theoretical analysis, a set of graphs has been developed which summarize the inviscid aerodynamics of delta wings at supersonic speeds. The various graphs which detail the aerodynamic performance of delta wings at both zero-lift and lifting conditions were then employed to define a preliminary wing design approach in which both the low-lift and high-lift design criteria were combined to define a feasible design space.

Aerodynamic Decelerators for Planetary Exploration: Past, Present, and Future

NASA Technical Reports Server (NTRS)

Cruz, Juna R.; Lingard, J. Stephen

2006-01-01

In this paper, aerodynamic decelerators are defined as textile devices intended to be deployed at Mach numbers below five. Such aerodynamic decelerators include parachutes and inflatable aerodynamic decelerators (often known as ballutes). Aerodynamic decelerators play a key role in the Entry, Descent, and Landing (EDL) of planetary exploration vehicles. Among the functions performed by aerodynamic decelerators for such vehicles are deceleration (often from supersonic to subsonic speeds), minimization of descent rate, providing specific descent rates (so that scientific measurements can be obtained), providing stability (drogue function - either to prevent aeroshell tumbling or to meet instrumentation requirements), effecting further aerodynamic decelerator system deployment (pilot function), providing differences in ballistic coefficients of components to enable separation events, and providing height and timeline to allow for completion of the EDL sequence. Challenging aspects in the development of aerodynamic decelerators for planetary exploration missions include: deployment in the unusual combination of high Mach numbers and low dynamic pressures, deployment in the wake behind a blunt-body entry vehicle, stringent mass and volume constraints, and the requirement for high drag and stability. Furthermore, these aerodynamic decelerators must be qualified for flight without access to the exotic operating environment where they are expected to operate. This paper is an introduction to the development and application of aerodynamic decelerators for robotic planetary exploration missions (including Earth sample return missions) from the earliest work in the 1960s to new ideas and technologies with possible application to future missions. An extensive list of references is provided for additional study.

A flight experiment to measure rarefied-flow aerodynamics

NASA Technical Reports Server (NTRS)

Blanchard, Robert C.

1990-01-01

A flight experiment to measure rarefied-flow aerodynamics of a blunt lifting body is being developed by NASA. This experiment, called the Rarefied-Flow Aerodynamic Measurement Experiment (RAME), is part of the Aeroassist Flight Experiment (AFE) mission, which is a Pathfinder design tool for aeroassisted orbital transfer vehicles. The RAME will use flight measurements from accelerometers, rate gyros, and pressure transducers, combined with knowledge of AFE in-flight mass properties and trajectory, to infer aerodynamic forces and moments in the rarefied-flow environment, including transition into the hypersonic continuum regime. Preflight estimates of the aerodynamic measurements are based upon environment models, existing computer simulations, and ground test results. Planned maneuvers at several altitudes will provide a first-time opportunity to examine gas-surface accommondation effects on aerodynamic coefficients in an environment of changing atmospheric composition. A description is given of the RAME equipment design.

A large-scale computer facility for computational aerodynamics

NASA Technical Reports Server (NTRS)

Bailey, F. R.; Ballhaus, W. F., Jr.

1985-01-01

As a result of advances related to the combination of computer system technology and numerical modeling, computational aerodynamics has emerged as an essential element in aerospace vehicle design methodology. NASA has, therefore, initiated the Numerical Aerodynamic Simulation (NAS) Program with the objective to provide a basis for further advances in the modeling of aerodynamic flowfields. The Program is concerned with the development of a leading-edge, large-scale computer facility. This facility is to be made available to Government agencies, industry, and universities as a necessary element in ensuring continuing leadership in computational aerodynamics and related disciplines. Attention is given to the requirements for computational aerodynamics, the principal specific goals of the NAS Program, the high-speed processor subsystem, the workstation subsystem, the support processing subsystem, the graphics subsystem, the mass storage subsystem, the long-haul communication subsystem, the high-speed data-network subsystem, and software.

Aerodynamics of high frequency flapping wings

NASA Astrophysics Data System (ADS)

Hu, Zheng; Roll, Jesse; Cheng, Bo; Deng, Xinyan

2010-11-01

We investigated the aerodynamic performance of high frequency flapping wings using a 2.5 gram robotic insect mechanism developed in our lab. The mechanism flaps up to 65Hz with a pair of man-made wing mounted with 10cm wingtip-to-wingtip span. The mean aerodynamic lift force was measured by a lever platform, and the flow velocity and vorticity were measured using a stereo DPIV system in the frontal, parasagittal, and horizontal planes. Both near field (leading edge vortex) and far field flow (induced flow) were measured with instantaneous and phase-averaged results. Systematic experiments were performed on the man-made wings, cicada and hawk moth wings due to their similar size, frequency and Reynolds number. For insect wings, we used both dry and freshly-cut wings. The aerodynamic force increase with flapping frequency and the man-made wing generates more than 4 grams of lift at 35Hz with 3 volt input. Here we present the experimental results and the major differences in their aerodynamic performances.

Fourier functional analysis for unsteady aerodynamic modeling

NASA Technical Reports Server (NTRS)

Lan, C. Edward; Chin, Suei

1991-01-01

A method based on Fourier analysis is developed to analyze the force and moment data obtained in large amplitude forced oscillation tests at high angles of attack. The aerodynamic models for normal force, lift, drag, and pitching moment coefficients are built up from a set of aerodynamic responses to harmonic motions at different frequencies. Based on the aerodynamic models of harmonic data, the indicial responses are formed. The final expressions for the models involve time integrals of the indicial type advocated by Tobak and Schiff. Results from linear two- and three-dimensional unsteady aerodynamic theories as well as test data for a 70-degree delta wing are used to verify the models. It is shown that the present modeling method is accurate in producing the aerodynamic responses to harmonic motions and the ramp type motions. The model also produces correct trend for a 70-degree delta wing in harmonic motion with different mean angles-of-attack. However, the current model cannot be used to extrapolate data to higher angles-of-attack than that of the harmonic motions which form the aerodynamic model. For linear ramp motions, a special method is used to calculate the corresponding frequency and phase angle at a given time. The calculated results from modeling show a higher lift peak for linear ramp motion than for harmonic ramp motion. The current model also shows reasonably good results for the lift responses at different angles of attack.

An Overview of Ares-I CFD Ascent Aerodynamic Data Development And Analysis Based on USM3D

NASA Technical Reports Server (NTRS)

Abdol-Hamid, Khaled S.; Ghaffari, Farhad; Parlette, Edward B.

2011-01-01

An overview of the computational results obtained from the NASA Langley developed unstructured grid, Reynolds-averaged Navier-Stokes flow solver USM3D, in support of the Ares-I project within the NASA s Constellation program, are presented. The numerical data are obtained for representative flow conditions pertinent to the ascent phase of the trajectory at both wind tunnel and flight Reynolds number without including any propulsion effects. The USM3D flow solver has been designated to have the primary role within the Ares-I project in developing the computational aerodynamic data for the vehicle while other flow solvers, namely OVERFLOW and FUN3D, have supporting roles to provide complementary results for fewer cases as part of the verification process to ensure code-to-code solution consistency. Similarly, as part of the solution validation efforts, the predicted numerical results are correlated with the aerodynamic wind tunnel data that have been generated within the project in the past few years. Sample aerodynamic results and the processes established for the computational solution/data development for the evolving Ares-I design cycles are presented.

NASA/Drexel program. [research effort in large-scale technical programs management for application to urban problems

NASA Technical Reports Server (NTRS)

1973-01-01

The results are reported of the NASA/Drexel research effort which was conducted in two separate phases. The initial phase stressed exploration of the problem from the point of view of three primary research areas and the building of a multidisciplinary team. The final phase consisted of a clinical demonstration program in which the research associates consulted with the County Executive of New Castle County, Delaware, to aid in solving actual problems confronting the County Government. The three primary research areas of the initial phase are identified as technology, management science, and behavioral science. Five specific projects which made up the research effort are treated separately. A final section contains the conclusions drawn from total research effort as well as from the specific projects.

Wind tunnel productivity status and improvement activities at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Putnam, Lawrence E.

1996-01-01

Over the last three years, a major effort has been underway to re-engineering the way wind tunnel testing is accomplished at the NASA Langley Research Center. This effort began with the reorganization of the LaRC and the consolidation of the management of the wind tunnels in the Aerodynamics Division under one operations branch. This paper provides an overview of the re-engineering activities and gives the status of the improvements in the wind tunnel productivity and customer satisfaction that have resulted from the new ways of working.

Langley's Computational Efforts in Sonic-Boom Softening of the Boeing HSCT

NASA Technical Reports Server (NTRS)

Fouladi, Kamran

1999-01-01

NASA Langley's computational efforts in the sonic-boom softening of the Boeing high-speed civil transport are discussed in this paper. In these efforts, an optimization process using a higher order Euler method for analysis was employed to reduce the sonic boom of a baseline configuration through fuselage camber and wing dihedral modifications. Fuselage modifications did not provide any improvements, but the dihedral modifications were shown to be an important tool for the softening process. The study also included aerodynamic and sonic-boom analyses of the baseline and some of the proposed "softened" configurations. Comparisons of two Euler methodologies and two propagation programs for sonic-boom predictions are also discussed in the present paper.

Derivation of aerodynamic kernel functions

NASA Technical Reports Server (NTRS)

Dowell, E. H.; Ventres, C. S.

1973-01-01

The method of Fourier transforms is used to determine the kernel function which relates the pressure on a lifting surface to the prescribed downwash within the framework of Dowell's (1971) shear flow model. This model is intended to improve upon the potential flow aerodynamic model by allowing for the aerodynamic boundary layer effects neglected in the potential flow model. For simplicity, incompressible, steady flow is considered. The proposed method is illustrated by deriving known results from potential flow theory.

The NASA Ames Hypervelocity Free Flight Aerodynamic Facility: Experimental Simulation of the Atmospheric Break-Up of Meteors

NASA Technical Reports Server (NTRS)

Wilder, M. C.; Bogdanoff, D. W.

2015-01-01

The Hypervelocity Free Flight Aerodynamic Facility at NASA Ames Research Center provides a potential platform for the experimental simulation of meteor breakup at conditions that closely match full-scale entry condition for select parameters. The poster describes the entry environment simulation capabilities of the Hypervelocity Free Flight Aerodynamic Facility (HFFAF) at NASA Ames Research Center and provides example images of the fragmentation of a hypersonic projectile for which break-up was initiated by mechanical forces (impact with a thin polymer diaphragm).

Control research in the NASA high-alpha technology program

NASA Technical Reports Server (NTRS)

Gilbert, William P.; Nguyen, Luat T.; Gera, Joseph

1990-01-01

NASA is conducting a focused technology program, known as the High-Angle-of-Attack Technology Program, to accelerate the development of flight-validated technology applicable to the design of fighters with superior stall and post-stall characteristics and agility. A carefully integrated effort is underway combining wind tunnel testing, analytical predictions, piloted simulation, and full-scale flight research. A modified F-18 aircraft has been extensively instrumented for use as the NASA High-Angle-of-Attack Research Vehicle used for flight verification of new methods and concepts. This program stresses the importance of providing improved aircraft control capabilities both by powered control (such as thrust-vectoring) and by innovative aerodynamic control concepts. The program is accomplishing extensive coordinated ground and flight testing to assess and improve available experimental and analytical methods and to develop new concepts for enhanced aerodynamics and for effective control, guidance, and cockpit displays essential for effective pilot utilization of the increased agility provided.

Aerodynamic preliminary analysis system 2. Part 1: Theory

NASA Technical Reports Server (NTRS)

Bonner, E.; Clever, W.; Dunn, K.

1981-01-01

A subsonic/supersonic/hypersonic aerodynamic analysis was developed by integrating the Aerodynamic Preliminary Analysis System (APAS), and the inviscid force calculation modules of the Hypersonic Arbitrary Body Program. APAS analysis was extended for nonlinear vortex forces using a generalization of the Polhamus analogy. The interactive system provides appropriate aerodynamic models for a single input geometry data base and has a run/output format similar to a wind tunnel test program. The user's manual was organized to cover the principle system activities of a typical application, geometric input/editing, aerodynamic evaluation, and post analysis review/display. Sample sessions are included to illustrate the specific task involved and are followed by a comprehensive command/subcommand dictionary used to operate the system.

Aerodynamic-structural model of offwind yacht sails

NASA Astrophysics Data System (ADS)

Mairs, Christopher M.

An aerodynamic-structural model of offwind yacht sails was created that is useful in predicting sail forces. Two sails were examined experimentally and computationally at several wind angles to explore a variety of flow regimes. The accuracy of the numerical solutions was measured by comparing to experimental results. The two sails examined were a Code 0 and a reaching asymmetric spinnaker. During experiment, balance, wake, and sail shape data were recorded for both sails in various configurations. Two computational steps were used to evaluate the computational model. First, an aerodynamic flow model that includes viscosity effects was used to examine the experimental flying shapes that were recorded. Second, the aerodynamic model was combined with a nonlinear, structural, finite element analysis (FEA) model. The aerodynamic and structural models were used iteratively to predict final flying shapes of offwind sails, starting with the design shapes. The Code 0 has relatively low camber and is used at small angles of attack. It was examined experimentally and computationally at a single angle of attack in two trim configurations, a baseline and overtrimmed setting. Experimentally, the Code 0 was stable and maintained large flow attachment regions. The digitized flying shapes from experiment were examined in the aerodynamic model. Force area predictions matched experimental results well. When the aerodynamic-structural tool was employed, the predictive capability was slightly worse. The reaching asymmetric spinnaker has higher camber and operates at higher angles of attack than the Code 0. Experimentally and computationally, it was examined at two angles of attack. Like the Code 0, at each wind angle, baseline and overtrimmed settings were examined. Experimentally, sail oscillations and large flow detachment regions were encountered. The computational analysis began by examining the experimental flying shapes in the aerodynamic model. In the baseline setting, the

Comparisons of several aerodynamic methods for application to dynamic loads analyses

NASA Technical Reports Server (NTRS)

Kroll, R. I.; Miller, R. D.

1976-01-01

The results of a study are presented in which the applicability at subsonic speeds of several aerodynamic methods for predicting dynamic gust loads on aircraft, including active control systems, was examined and compared. These aerodynamic methods varied from steady state to an advanced unsteady aerodynamic formulation. Brief descriptions of the structural and aerodynamic representations and of the motion and load equations are presented. Comparisons of numerical results achieved using the various aerodynamic methods are shown in detail. From these results, aerodynamic representations for dynamic gust analyses are identified. It was concluded that several aerodynamic methods are satisfactory for dynamic gust analyses of configurations having either controls fixed or active control systems that primarily affect the low frequency rigid body aircraft response.

Turbofan Engine Core Compartment Vent Aerodynamic Configuration Development Methodology

NASA Technical Reports Server (NTRS)

Hebert, Leonard J.

2006-01-01

This paper presents an overview of the design methodology used in the development of the aerodynamic configuration of the nacelle core compartment vent for a typical Boeing commercial airplane together with design challenges for future design efforts. Core compartment vents exhaust engine subsystem flows from the space contained between the engine case and the nacelle of an airplane propulsion system. These subsystem flows typically consist of precooler, oil cooler, turbine case cooling, compartment cooling and nacelle leakage air. The design of core compartment vents is challenging due to stringent design requirements, mass flow sensitivity of the system to small changes in vent exit pressure ratio, and the need to maximize overall exhaust system performance at cruise conditions.

Group-effort applied research: expanding opportunities for undergraduate research through original, class-based research projects.

PubMed

Moore, Sean D; Teter, Ken

2014-01-01

Undergraduate research clearly enriches the educational development of participating students, but these experiences are limited by the inherent inefficiency of the standard one student-one mentor model for undergraduate research. Group-effort applied research (GEAR) was developed as a strategy to provide substantial numbers of undergraduates with meaningful research experiences. The GEAR curriculum delivers concept-driven lecture material and provides hands-on training in the context of an active research project from the instructor's laboratory. Because GEAR is structured as a class, participating students benefit from intensive, supervised research training that involves a built-in network of peer support and abundant contact with faculty mentors. The class format also ensures a relatively standardized and consistent research experience. Furthermore, meaningful progress toward a research objective can be achieved more readily with GEAR than with the traditional one student-one mentor model of undergraduate research because sporadic mistakes by individuals in the class are overshadowed by the successes of the group as a whole. Three separate GEAR classes involving three distinct research projects have been offered to date. In this article, we provide an overview of the GEAR format and review some of the recurring themes for GEAR instruction. We propose GEAR can serve as a template to expand student opportunities for life science research without sacrificing the quality of the mentored research experience. © 2014 The International Union of Biochemistry and Molecular Biology.

The aerodynamics of small Reynolds numbers

NASA Technical Reports Server (NTRS)

Schmitz, F. W.

1980-01-01

Aerodynamic characteristics of wing model gliders and bird wings in particular are discussed. Wind tunnel measurements and aerodynamics of small Reynolds numbers are enumerated. Airfoil behavior in the critical transition from laminar to turbulent boundary layer, which is more important to bird wing models than to large airplanes, was observed. Experimental results are provided, and an artificial bird wing is described.

Aerodynamic analysis of formula student car

NASA Astrophysics Data System (ADS)

Dharmawan, Mohammad Arief; Ubaidillah, Nugraha, Arga Ahmadi; Wijayanta, Agung Tri; Naufal, Brian Aqif

2018-02-01

Formula Society of Automotive Engineering (FSAE) is a contest between ungraduated students to create a high-performance formula student car that completes the regulation. Body and the other aerodynamic devices are significant because it affects the drag coefficient and the down force of the car. The drag coefficient is a measurement of the resistance of an object in a fluid environment, a lower the drag coefficient means it will have a less drag force. Down force is a force that pushes an object to the ground, in the car more down force means more grip. The objective of the research was to study the aerodynamic comparison between the race vehicle when attached to the wings and without it. These studies were done in three dimensional (3D) computational fluid dynamic (CFD) simulation method using the Autodesk Flow Design software. These simulations were done by conducted in 5 different velocities. The results of those simulations are by attaching wings on race vehicle has drag coefficient 0.728 and without wings has drag coefficient 0.56. Wings attachment will decrease the drag coefficient about 23 % and also the contour pressure and velocity were known at these simulations.

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

NASA Technical Reports Server (NTRS)

Driggers, H. H.; Powers, S. A.; Roush, R. T.

1982-01-01

A conceptual design analysis is performed on a single engine V/STOL supersonic fighter/attack concept powered by a series flow tandem fan propulsion system. Forward and aft mounted fans have independent flow paths for V/STOL operation and series flow in high speed flight. Mission, combat and V/STOL performance is calculated. Detailed aerodynamic estimates are made and aerodynamic uncertainties associated with the configuration and estimation methods identified. A wind tunnel research program is developed to resolve principal uncertainties and establish a data base for the baseline configuration and parametric variations.

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.

Icing flight research: Aerodynamic effects of ice and ice shape documentation with stereo photography

NASA Technical Reports Server (NTRS)

Mikkelsen, K. L.; Mcknight, R. C.; Ranaudo, R. J.; Perkins, P. J., Jr.

1985-01-01

Aircraft icing flight research was performed in natural icing conditions. A data base consisting of icing cloud measurements, ice shapes, and aerodynamic measurements is being developed. During research icing encounters the icing cloud was continuously measured. After the encounter, the ice accretion shapes on the wing were documented with a stereo camera system. The increase in wing section drag was measured with a wake survey probe. The overall aircraft performance loss in terms of lift and drag coefficient changes was obtained by steady level speed/power measurements. Selective deicing of the airframe components was performed to determine their contributions to the total drag increase. Engine out capability in terms of power available was analyzed for the iced aircraft. It was shown that the stereo photography system can be used to document ice shapes in flight and that the wake survey probe can measure increases in wing section drag caused by ice. On one flight, the wing section drag coefficient (c sub d) increased approximately 120 percent over the uniced baseline at an aircraft angle of attack of 6 deg. On another flight, the aircraft darg coefficient (c sub d) increased by 75 percent over the uniced baseline at an aircraft lift coefficient (C sub d) of 0.5.

Icing flight research - Aerodynamic effects of ice and ice shape documentation with stereo photography

NASA Technical Reports Server (NTRS)

Mikkelsen, K. L.; Mcknight, R. C.; Ranaudo, R. J.; Perkins, P. J., Jr.

1985-01-01

Aircraft icing flight research was performed in natural icing conditions. A data base consisting of icing cloud measurements, ice shapes, and aerodynamic measurements is being developed. During research icing encounters the icing cloud was continuously measured. After the encounter, the ice accretion shapes on the wing were documented with a stereo camera system. The increase in wing section drag was measured with a wake survey probe. The overall aircraft performance loss in terms of lift and drag coefficient changes were obtained by steady level speed/power measurements. Selective deicing of the airframe components was performed to determine their contributions to the total drag increase. Engine out capability in terms of power available was analyzed for the iced aircraft. It was shown that the stereo photography system can be used to document ice shapes in flight and that the wake survey probe can measure increases in wing section drag caused by ice. On one flight, the wing section drag coefficient (c sub d) increased approximately 120 percent over the uniced baseline at an aircraft angle of attack of 6 deg. On another flight, the aircraft drag coefficient (c sub d) increased by 75 percent over the uniced baseline at an aircraft lift coefficient (c sub d) of 0.5.

Unsteady Aerodynamic Force Sensing from Strain Data

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi

2017-01-01

A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm.

Modelling Aerodynamically Generated Sound: Recent Advances in Rotor Noise Prediction

NASA Technical Reports Server (NTRS)

Brentner, Kenneth S.

2000-01-01

A great deal of progress has been made in the modeling of aerodynamically generated sound for rotors over the past decade. The Ffowcs Williams-Hawkings (FW-H ) equation has been the foundation for much of the development. Both subsonic and supersonic quadrupole noise formulations have been developed for the prediction of high-speed impulsive noise. In an effort to eliminate the need to compute the quadrupole contribution, the FW-H has also been utilized on permeable surfaces surrounding all physical noise sources. Comparison of the Kirchhoff formulation for moving surfaces with the FW-H equation have shown that the Kirchhoff formulation for moving surfaces can give erroneous results for aeroacoustic problems.

Aerodynamic and Aerothermal TPS Instrumentation Reference Guide

NASA Technical Reports Server (NTRS)

Woollard, Bryce A.; Braun, Robert D.; Bose, Deepack

2016-01-01

The hypersonic regime of planetary entry combines the most severe environments that an entry vehicle will encounter with the greatest amount of uncertainty as to the events unfolding during that time period. This combination generally leads to conservatism in the design of an entry vehicle, specifically that of the thermal protection system (TPS). Each planetary entry provides a valuable aerodynamic and aerothermal testing opportunity; the utilization of this opportunity is paramount in better understanding how a specific entry vehicle responds to the demands of the hypersonic entry environment. Previous efforts have been made to instrument entry vehicles in order to collect data during the entry period and reconstruct the corresponding vehicle response. The purpose of this paper is to cumulatively document past TPS instrumentation designs for applicable planetary missions, as well as to list pertinent results and any explainable shortcomings.

Study on the Influence of the Convoy Rolling over Aerodynamic Resistance

NASA Astrophysics Data System (ADS)

Iozsa, D.; Stan, C.; Ilea, L.

2017-10-01

The aim of the study is to investigate how the aerodynamic resistance is influenced by the convoy rolling and to see how much this is possible by varying the distance between trucks. Then to see how the gains correlate with the position occupied by the truck in the convoy. The study starts from current research on the premises of running in convoy. Aerodynamic analysis was performed using software finite element of Computational Fluid Dynamics (CFD) type, where it was modeled the convoy rolling of a variable number of trucks. The number of trucks and the distance between them was varied in the model in order to acquire an understanding of the flow field around the trucks and how the distance between them can improve the aerodynamic parameters. The results are presented in the form of streamlines of the air, which indicates the air volume travel speed and direction and of the pressure distribution on the surface of the body. The most significant drop in pressure on the front surface was obtained for the second truck of the convoy, whereas for the following ones the reduction was less important. The participation in a convoy of more than two trucks is justified by the reduction of the whirls that appear and by the uniform air flow. The main advantage of running in convoy mode is to decrease aerodynamic resistance, with beneficial consequences on economic and ecological parameters. Continuing work from here on, it could be analyzed the impact of changing the distance between trucks on the aerodynamic coefficient. The results of CFD simulations need to be verified with experimental data, such as wind-tunnel test, to ensure reliability of the results.

Lateral and longitudinal aerodynamic stability and control parameters of the basic vortex flap research aircraft as determined from flight test data

NASA Technical Reports Server (NTRS)

Suit, W. T.; Batterson, J. G.

1986-01-01

The aerodynamics of the basic F-106B were determined at selected points in the flight envelope. The test aircraft and flight procedures were presented. Aircraft instrumentation and the data system were discussed. The parameter extraction procedure was presented along with a discussion of the test flight results. The results were used to predict the aircraft motions for maneuvers that were not used to determine the vehicle aerodynamics. The control inputs used to maneuver the aircraft to get data for the determination of the aerodynamic parameters were discussed in the flight test procedures. The results from the current flight tests were compared with the results from wind tunnel test of the basic F-106B.

The finite element method in low speed aerodynamics

NASA Technical Reports Server (NTRS)

Baker, A. J.; Manhardt, P. D.

1975-01-01

The finite element procedure is shown to be of significant impact in design of the 'computational wind tunnel' for low speed aerodynamics. The uniformity of the mathematical differential equation description, for viscous and/or inviscid, multi-dimensional subsonic flows about practical aerodynamic system configurations, is utilized to establish the general form of the finite element algorithm. Numerical results for inviscid flow analysis, as well as viscous boundary layer, parabolic, and full Navier Stokes flow descriptions verify the capabilities and overall versatility of the fundamental algorithm for aerodynamics. The proven mathematical basis, coupled with the distinct user-orientation features of the computer program embodiment, indicate near-term evolution of a highly useful analytical design tool to support computational configuration studies in low speed aerodynamics.

Space Launch System Ascent Static Aerodynamic Database Development

NASA Technical Reports Server (NTRS)

Pinier, Jeremy T.; Bennett, David W.; Blevins, John A.; Erickson, Gary E.; Favaregh, Noah M.; Houlden, Heather P.; Tomek, William G.

2014-01-01

This paper describes the wind tunnel testing work and data analysis required to characterize the static aerodynamic environment of NASA's Space Launch System (SLS) ascent portion of flight. Scaled models of the SLS have been tested in transonic and supersonic wind tunnels to gather the high fidelity data that is used to build aerodynamic databases. A detailed description of the wind tunnel test that was conducted to produce the latest version of the database is presented, and a representative set of aerodynamic data is shown. The wind tunnel data quality remains very high, however some concerns with wall interference effects through transonic Mach numbers are also discussed. Post-processing and analysis of the wind tunnel dataset are crucial for the development of a formal ascent aerodynamics database.

Application Program Interface for the Orion Aerodynamics Database

NASA Technical Reports Server (NTRS)

Robinson, Philip E.; Thompson, James

2013-01-01

The Application Programming Interface (API) for the Crew Exploration Vehicle (CEV) Aerodynamic Database has been developed to provide the developers of software an easily implemented, fully self-contained method of accessing the CEV Aerodynamic Database for use in their analysis and simulation tools. The API is programmed in C and provides a series of functions to interact with the database, such as initialization, selecting various options, and calculating the aerodynamic data. No special functions (file read/write, table lookup) are required on the host system other than those included with a standard ANSI C installation. It reads one or more files of aero data tables. Previous releases of aerodynamic databases for space vehicles have only included data tables and a document of the algorithm and equations to combine them for the total aerodynamic forces and moments. This process required each software tool to have a unique implementation of the database code. Errors or omissions in the documentation, or errors in the implementation, led to a lengthy and burdensome process of having to debug each instance of the code. Additionally, input file formats differ for each space vehicle simulation tool, requiring the aero database tables to be reformatted to meet the tool s input file structure requirements. Finally, the capabilities for built-in table lookup routines vary for each simulation tool. Implementation of a new database may require an update to and verification of the table lookup routines. This may be required if the number of dimensions of a data table exceeds the capability of the simulation tools built-in lookup routines. A single software solution was created to provide an aerodynamics software model that could be integrated into other simulation and analysis tools. The highly complex Orion aerodynamics model can then be quickly included in a wide variety of tools. The API code is written in ANSI C for ease of portability to a wide variety of systems. The

Optimization of rotor blades for combined structural, dynamic, and aerodynamic properties

NASA Technical Reports Server (NTRS)

He, Cheng-Jian; Peters, David A.

1990-01-01

Optimal helicopter blade design with computer-based mathematical programming has received more and more attention in recent years. Most of the research has focused on optimum dynamic characteristics of rotor blades to reduce vehicle vibration. There is also work on optimization of aerodynamic performance and on composite structural design. This research has greatly increased our understanding of helicopter optimum design in each of these aspects. Helicopter design is an inherently multidisciplinary process involving strong interactions among various disciplines which can appropriately include aerodynamics; dynamics, both flight dynamics and structural dynamics; aeroelasticity: vibrations and stability; and even acoustics. Therefore, the helicopter design process must satisfy manifold requirements related to the aforementioned diverse disciplines. In our present work, we attempt to combine several of these important effects in a unified manner. First, we design a blade with optimum aerodynamic performance by proper layout of blade planform and spanwise twist. Second, the blade is designed to have natural frequencies that are placed away from integer multiples of the rotor speed for a good dynamic characteristics. Third, the structure is made as light as possible with sufficient rotational inertia to allow for autorotational landing, with safe stress margins and flight fatigue life at each cross-section, and with aeroelastical stability and low vibrations. Finally, a unified optimization refines the solution.

Aerodynamic Flight-Test Results for the Adaptive Compliant Trailing Edge

NASA Technical Reports Server (NTRS)

Cumming, Stephen B.; Smith, Mark S.; Ali, Aliyah N.; Bui, Trong T.; Ellsworth, Joel C.; Garcia, Christian A.

2016-01-01

The aerodynamic effects of compliant flaps installed onto a modified Gulfstream III airplane were investigated. Analyses were performed prior to flight to predict the aerodynamic effects of the flap installation. Flight tests were conducted to gather both structural and aerodynamic data. The airplane was instrumented to collect vehicle aerodynamic data and wing pressure data. A leading-edge stagnation detection system was also installed. The data from these flights were analyzed and compared with predictions. The predictive tools compared well with flight data for small flap deflections, but differences between predictions and flight estimates were greater at larger deflections. This paper describes the methods used to examine the aerodynamics data from the flight tests and provides a discussion of the flight-test results in the areas of vehicle aerodynamics, wing sectional pressure coefficient profiles, and air data.

Physical Insights, Steady Aerodynamic Effects, and a Design Tool for Low-Pressure Turbine Flutter

NASA Astrophysics Data System (ADS)

Waite, Joshua Joseph

The successful, efficient, and safe turbine design requires a thorough understanding of the underlying physical phenomena. This research investigates the physical understanding and parameters highly correlated to flutter, an aeroelastic instability prevalent among low pressure turbine (LPT) blades in both aircraft engines and power turbines. The modern way of determining whether a certain cascade of LPT blades is susceptible to flutter is through time-expensive computational fluid dynamics (CFD) codes. These codes converge to solution satisfying the Eulerian conservation equations subject to the boundary conditions of a nodal domain consisting fluid and solid wall particles. Most detailed CFD codes are accompanied by cryptic turbulence models, meticulous grid constructions, and elegant boundary condition enforcements all with one goal in mind: determine the sign (and therefore stability) of the aerodynamic damping. The main question being asked by the aeroelastician, "is it positive or negative?'' This type of thought-process eventually gives rise to a black-box effect, leaving physical understanding behind. Therefore, the first part of this research aims to understand and reveal the physics behind LPT flutter in addition to several related topics including acoustic resonance effects. A percentage of this initial numerical investigation is completed using an influence coefficient approach to study the variation the work-per-cycle contributions of neighboring cascade blades to a reference airfoil. The second part of this research introduces new discoveries regarding the relationship between steady aerodynamic loading and negative aerodynamic damping. Using validated CFD codes as computational wind tunnels, a multitude of low-pressure turbine flutter parameters, such as reduced frequency, mode shape, and interblade phase angle, will be scrutinized across various airfoil geometries and steady operating conditions to reach new design guidelines regarding the influence

The aerodynamic analysis of the gyroplane rotating-wing system

NASA Technical Reports Server (NTRS)

Wheatley, John B

1934-01-01

An aerodynamic analysis of the gyroplane rotating-wing system is presented herein. This system consists of a freely rotating rotor in which opposite blades are rigidly connected and allowed to rotate or feather freely about their span axis. Equations have been derived for the lift, the lift-drag ratio, the angle of attack, the feathering angles, and the rolling and pitching moments of a gyroplane rotor in terms of its basic parameters. Curves of lift-drag ratio against lift coefficient have been calculated for a typical case, showing the effect of varying the pitch angle, the solidarity, and the average blade-section drag coefficient. The analysis expresses satisfactorily the qualitative relations between the rotor characteristics and the rotor parameters. As disclosed by this investigation, the aerodynamic principles of the gyroplane are sound, and further research on this wing system is justified.

Unsteady Aerodynamic Model Tuning for Precise Flutter Prediction

NASA Technical Reports Server (NTRS)

Pak, Chan-gi

2011-01-01

A simple method for an unsteady aerodynamic model tuning is proposed in this study. This method is based on the direct modification of the aerodynamic influence coefficient matrices. The aerostructures test wing 2 flight-test data is used to demonstrate the proposed model tuning method. The flutter speed margin computed using only the test validated structural dynamic model can be improved using the additional unsteady aerodynamic model tuning, and then the flutter speed margin requirement of 15 percent in military specifications can apply towards the test validated aeroelastic model. In this study, unsteady aerodynamic model tunings are performed at two time invariant flight conditions, at Mach numbers of 0.390 and 0.456. When the Mach number for the unsteady aerodynamic model tuning approaches to the measured fluttering Mach number, 0.502, at the flight altitude of 9,837 ft, the estimated flutter speed is approached to the measured flutter speed at this altitude. The minimum flutter speed difference between the estimated and measured flutter speed is -0.14 percent.

Intermediate Experimental Vehicle, ESA Programme Supersonic Transonic Aerodynamics

NASA Astrophysics Data System (ADS)

Sjors, Karin; Olsson, Jorgen; Maseland, Hans; de Cock, Koen; Dutheil, Sylvain; Bouleuc, Laurent; Cantinaud, Olivier; Tribot, Jean-Pierre; Mareschi, Vincenzo; Ferrarella, Daniella, Rufolo, Giuseppe

2011-05-01

The IXV project objectives are the design, development, manufacture and on ground and in flight verification of an autonomous European lifting and aerodynamically controlled re-entry system, which is highly flexible and manoeuvrable. The IXV vehicle is planned to be recovered in supersonic regime by means of a Descent and Recovery System (DRS). In that context, a specific aerodynamic identification was carried in order to provide data to be used for consolidating the AEDB (AErodynamic Data Base) and as inputs for the DRS sub-system activities. During the phase C2, a wind tunnel campaign was carried out at for the Mach number range M=1.7 to M=0.3 together with computational fluid dynamics simulation. The main objectives were to assess the aerodynamic forces and moments assuming high aileron setting in supersonic regime and to get preliminary aerodynamic data in subsonic regime to be used as input by the DRS team. The logic and the main results of these activities are presented and discussed in this paper.

Aerodynamic Leidenfrost effect

NASA Astrophysics Data System (ADS)

Gauthier, Anaïs; Bird, James C.; Clanet, Christophe; Quéré, David

2016-12-01

When deposited on a plate moving quickly enough, any liquid can levitate as it does when it is volatile on a very hot solid (Leidenfrost effect). In the aerodynamic Leidenfrost situation, air gets inserted between the liquid and the moving solid, a situation that we analyze. We observe two types of entrainment. (i) The thickness of the air gap is found to increase with the plate speed, which is interpreted in the Landau-Levich-Derjaguin frame: Air is dynamically dragged along the surface and its thickness results from a balance between capillary and viscous effects. (ii) Air set in motion by the plate exerts a force on the levitating liquid. We discuss the magnitude of this aerodynamic force and show that it can be exploited to control the liquid and even to drive it against gravity.

Aerodynamic Simulation of Runback Ice Accretion

NASA Technical Reports Server (NTRS)

Broeren, Andy P.; Whalen, Edward A.; Busch, Greg T.; Bragg, Michael B.

2010-01-01

This report presents the results of recent investigations into the aerodynamics of simulated runback ice accretion on airfoils. Aerodynamic tests were performed on a full-scale model using a high-fidelity, ice-casting simulation at near-flight Reynolds (Re) number. The ice-casting simulation was attached to the leading edge of a 72-in. (1828.8-mm ) chord NACA 23012 airfoil model. Aerodynamic performance tests were conducted at the ONERA F1 pressurized wind tunnel over a Reynolds number range of 4.7?10(exp 6) to 16.0?10(exp 6) and a Mach (M) number ran ge of 0.10 to 0.28. For Re = 16.0?10(exp 6) and M = 0.20, the simulated runback ice accretion on the airfoil decreased the maximum lift coe fficient from 1.82 to 1.51 and decreased the stalling angle of attack from 18.1deg to 15.0deg. The pitching-moment slope was also increased and the drag coefficient was increased by more than a factor of two. In general, the performance effects were insensitive to Reynolds numb er and Mach number changes over the range tested. Follow-on, subscale aerodynamic tests were conducted on a quarter-scale NACA 23012 model (18-in. (457.2-mm) chord) at Re = 1.8?10(exp 6) and M = 0.18, using low-fidelity, geometrically scaled simulations of the full-scale castin g. It was found that simple, two-dimensional simulations of the upper- and lower-surface runback ridges provided the best representation of the full-scale, high Reynolds number iced-airfoil aerodynamics, whereas higher-fidelity simulations resulted in larger performance degrada tions. The experimental results were used to define a new subclassification of spanwise ridge ice that distinguishes between short and tall ridges. This subclassification is based upon the flow field and resulting aerodynamic characteristics, regardless of the physical size of the ridge and the ice-accretion mechanism.

Evaluation of aerodynamic derivatives from a magnetic balance system

NASA Technical Reports Server (NTRS)

Raghunath, B. S.; Parker, H. M.

1972-01-01

The dynamic testing of a model in the University of Virginia cold magnetic balance wind-tunnel facility is expected to consist of measurements of the balance forces and moments, and the observation of the essentially six degree of freedom motion of the model. The aerodynamic derivatives of the model are to be evaluated from these observations. The basic feasibility of extracting aerodynamic information from the observation of a model which is executing transient, complex, multi-degree of freedom motion is demonstrated. It is considered significant that, though the problem treated here involves only linear aerodynamics, the methods used are capable of handling a very large class of aerodynamic nonlinearities. The basic considerations include the effect of noise in the data on the accuracy of the extracted information. Relationships between noise level and the accuracy of the evaluated aerodynamic derivatives are presented.

Aerodynamic database development of the ESA intermediate experimental vehicle

NASA Astrophysics Data System (ADS)

Pezzella, Giuseppe; Marino, Giuliano; Rufolo, Giuseppe C.

2014-01-01

This work deals with the aerodynamic database development of the Intermediate Experiment Vehicle. The aerodynamic analysis, carried out for the whole flight scenario, relies on computational fluid dynamics, wind tunnel test, and engineering-based design data generated during the project phases, from rarefied flow conditions, to hypersonic continuum flow up to reach subsonic speeds regime. Therefore, the vehicle aerodynamic database covers the range of Mach number, angle of attack, sideslip and control surface deflections foreseen for the vehicle nominal re-entry. In particular, the databasing activities are developed in the light of build-up approach. This means that all aerodynamic force and moment coefficients are provided by means of a linear summation over certain number of incremental contributions such as, for example, effect of sideslip angle, aerodynamic control surface effectiveness, etc. Each force and moment coefficient is treated separately and appropriate equation is provided, in which all the pertinent contributions for obtaining the total coefficient for any selected flight conditions appear. To this aim, all the available numerical and experimental aerodynamic data are gathered in order to explicit the functional dependencies from each aerodynamic model addend through polynomial expressions obtained with the least squares method. These polynomials are function of the primary variable that drives the phenomenon whereas secondary dependencies are introduced directly into its unknown coefficients which are determined by means of best-fitting algorithms.

Progress in high-lift aerodynamic calculations

NASA Technical Reports Server (NTRS)

Rogers, Stuart E.

1993-01-01

The current work presents progress in the effort to numerically simulate the flow over high-lift aerodynamic components, namely, multi-element airfoils and wings in either a take-off or a landing configuration. The computational approach utilizes an incompressible flow solver and an overlaid chimera grid approach. A detailed grid resolution study is presented for flow over a three-element airfoil. Two turbulence models, a one-equation Baldwin-Barth model and a two equation k-omega model are compared. Excellent agreement with experiment is obtained for the lift coefficient at all angles of attack, including the prediction of maximum lift when using the two-equation model. Results for two other flap riggings are shown. Three-dimensional results are presented for a wing with a square wing-tip as a validation case. Grid generation and topology is discussed for computing the flow over a T-39 Sabreliner wing with flap deployed and the initial calculations for this geometry are presented.

Development of a superconductor magnetic suspension and balance prototype facility for studying the feasibility of applying this technique to large scale aerodynamic testing

NASA Technical Reports Server (NTRS)

Zapata, R. N.; Humphris, R. R.; Henderson, K. C.

1975-01-01

The basic research and development work towards proving the feasibility of operating an all-superconductor magnetic suspension and balance device for aerodynamic testing is presented. The feasibility of applying a quasi-six-degree-of freedom free support technique to dynamic stability research was studied along with the design concepts and parameters for applying magnetic suspension techniques to large-scale aerodynamic facilities. A prototype aerodynamic test facility was implemented. Relevant aspects of the development of the prototype facility are described in three sections: (1) design characteristics; (2) operational characteristics; and (3) scaling to larger facilities.

The research progress on Hodograph Method of aerodynamic design at Tsinghua University

NASA Technical Reports Server (NTRS)

Chen, Zuoyi; Guo, Jingrong

1991-01-01

Progress in the use of the Hodograph method of aerodynamic design is discussed. It was found that there are some restricted conditions in the application of Hodograph design to transonic turbine and compressor cascades. The Hodograph method is suitable not only to the transonic turbine cascade but also to the transonic compressor cascade. The three dimensional Hodograph method will be developed after obtaining the basic equation for the three dimensional Hodograph method. As an example of the Hodograph method, the use of the method to design a transonic turbine and compressor cascade is discussed.

Identification of Aerodynamic Coefficients Using Computational Neural Networks

DTIC Science & Technology

1992-01-09

the Am-. icar , Institete ur Aeronautics and mation model, excellent matches of aerodynamic coef- Astronautics, Inc. All rights reserved. ficient...UL NSN 7540-01-2EO-SSO0 Standard Form 296 (Rev. 2-89) ft"""~e by Ar t4ed. Z39-1 SAIA A_ AIAA 92-0172 Identification of Aerodynamic Coefficients Using...state and control space. While the partitions span the space, these global models are, in general, not contin- Precise, smooth aerodynamic models are

System Identification of a Vortex Lattice Aerodynamic Model

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Kholodar, Denis; Dowell, Earl H.

2001-01-01

The state-space presentation of an aerodynamic vortex model is considered from a classical and system identification perspective. Using an aerodynamic vortex model as a numerical simulator of a wing tunnel experiment, both full state and limited state data or measurements are considered. Two possible approaches for system identification are presented and modal controllability and observability are also considered. The theory then is applied to the system identification of a flow over an aerodynamic delta wing and typical results are presented.

Aerodynamic Lifting Force.

ERIC Educational Resources Information Center

Weltner, Klaus

1990-01-01

Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

High Reynolds number research - 1980

NASA Technical Reports Server (NTRS)

Mckinney, L. W. (Editor); Baals, D. D. (Editor)

1981-01-01

The fundamental aerodynamic questions for which high Reynolds number experimental capability is required were examined. Potential experiments which maximize the research returns from the use of the National Transonic Facility (NTF) were outlined. Calibration plans were reviewed and the following topics were discussed: fluid dynamics; high lit; configuration aerodynamics; aeroelasticity and unsteady aerodynamics; wind tunnel/flight correlation; space vehicles; and theoretical aerodynamics

Group-Effort Applied Research (GEAR): Expanding Opportunities for Undergraduate Research Through Original, Class-Based Research Projects

PubMed Central

Moore, Sean D.; Teter, Ken

2014-01-01

Undergraduate research clearly enriches the educational development of participating students, but these experiences are limited by the inherent inefficiency of the standard one student - one mentor model for undergraduate research. Group-Effort Applied Research (GEAR) was developed as a strategy to provide substantial numbers of undergraduates with meaningful research experiences. The GEAR curriculum delivers concept-driven lecture material and provides hands-on training in the context of an active research project from the instructor's lab. Because GEAR is structured as a class, participating students benefit from intensive, supervised research training that involves a built-in network of peer support and abundant contact with faculty mentors. The class format also ensures a relatively standardized and consistent research experience. Furthermore, meaningful progress toward a research objective can be achieved more readily with GEAR than with the traditional one student - one mentor model of undergraduate research because sporadic mistakes by individuals in the class are overshadowed by the successes of the group as a whole. Three separate GEAR classes involving three distinct research projects have been offered to date. In this paper, we provide an overview of the GEAR format and review some of the recurring themes for GEAR instruction. We propose GEAR can serve as a template to expand student opportunities for life science research without sacrificing the quality of the mentored research experience. PMID:24898007

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.

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.

Unsteady aerodynamic analysis of space shuttle vehicles. Part 4: Effect of control deflections on orbiter unsteady aerodynamics

NASA Technical Reports Server (NTRS)

Reding, J. P.; Ericsson, L. E.

1973-01-01

The unsteady aerodynamics of the 040A orbiter have been explored experimentally. The results substantiate earlier predictions of the unsteady flow boundaries for a 60 deg swept delta wing at zero yaw and with no controls deflected. The test revealed a previously unknown region of discontinuous yaw characteristics at transonic speeds. Oilflow results indicate that this is the result of a coupling between wing and fuselage flows via the separated region forward of the deflected elevon. In fact, the large leeward elevon deflections are shown to produce a multitude of nonlinear stability effects which sometimes involve hysteresis. Predictions of the unsteady flow boundaries are made for the current orbiter. They should carry a good degree of confidence due to the present substantiation of previous predictions for the 040A. It is proposed that the present experiments be extended to the current configuration to define control-induced effects. Every effort should be made to account for Reynolds number, roughness, and possible hot-wall effects on any future experiments.

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.

Supersonic Flight Dynamics Test: Trajectory, Atmosphere, and Aerodynamics Reconstruction

NASA Technical Reports Server (NTRS)

Kutty, Prasad; Karlgaard, Christopher D.; Blood, Eric M.; O'Farrell, Clara; Ginn, Jason M.; Shoenenberger, Mark; Dutta, Soumyo

2015-01-01

The Supersonic Flight Dynamics Test is a full-scale flight test of a Supersonic Inflatable Aerodynamic Decelerator, which is part of the Low Density Supersonic Decelerator technology development project. The purpose of the project is to develop and mature aerodynamic decelerator technologies for landing large mass payloads on the surface of Mars. The technologies include a Supersonic Inflatable Aerodynamic Decelerator and Supersonic Parachutes. The first Supersonic Flight Dynamics Test occurred on June 28th, 2014 at the Pacific Missile Range Facility. This test was used to validate the test architecture for future missions. The flight was a success and, in addition, was able to acquire data on the aerodynamic performance of the supersonic inflatable decelerator. This paper describes the instrumentation, analysis techniques, and acquired flight test data utilized to reconstruct the vehicle trajectory, atmosphere, and aerodynamics. The results of the reconstruction show significantly higher lofting of the trajectory, which can partially be explained by off-nominal booster motor performance. The reconstructed vehicle force and moment coefficients fall well within pre-flight predictions. A parameter identification analysis indicates that the vehicle displayed greater aerodynamic static stability than seen in pre-flight computational predictions and ballistic range tests.

Ares I Aerodynamic Testing at the Boeing Polysonic Wind Tunnel

NASA Technical Reports Server (NTRS)

Pinier, Jeremy T.; Niskey, Charles J.; Hanke, Jeremy L.; Tomek, William G.

2011-01-01

Throughout three full design analysis cycles, the Ares I project within the Constellation program has consistently relied on the Boeing Polysonic Wind Tunnel (PSWT) for aerodynamic testing of the subsonic, transonic and supersonic portions of the atmospheric flight envelope (Mach=0.5 to 4.5). Each design cycle required the development of aerodynamic databases for the 6 degree-of-freedom (DOF) forces and moments, as well as distributed line-loads databases covering the full range of Mach number, total angle-of-attack, and aerodynamic roll angle. The high fidelity data collected in this facility has been consistent with the data collected in NASA Langley s Unitary Plan Wind Tunnel (UPWT) at the overlapping condition ofMach=1.6. Much insight into the aerodynamic behavior of the launch vehicle during all phases of flight was gained through wind tunnel testing. Important knowledge pertaining to slender launch vehicle aerodynamics in particular was accumulated. In conducting these wind tunnel tests and developing experimental aerodynamic databases, some challenges were encountered and are reported as lessons learned in this paper for the benefit of future crew launch vehicle aerodynamic developments.

An Aerodynamic Investigation of a Forward Swept Wing

DTIC Science & Technology

1977-12-01

attached flow at higher angles of attack. 59 -. - . -- ~II The use of winglets should-also be considered to determine their effect on the aerodynamic ...INVSTGAIO OF A" ’/7AI/A/A7D1 ¾~nnt ¾ý’i ~~~)a al -A ApprovedYA~I forSIATO OFli Aees;dsrbuinulmtd AFIT/GAE/AA/77D -4 .1 AN AERODYNAMIC INVESTIGATION OF A...this study was to experimentally and analytically determine certain aerodynamic characteristics of a recently proposed high subsonic, forward swept wing

Analysis and Improvement of Aerodynamic Performance of Straight Bladed Vertical Axis Wind Turbines

NASA Astrophysics Data System (ADS)

Ahmadi-Baloutaki, Mojtaba

Vertical axis wind turbines (VAWTs) with straight blades are attractive for their relatively simple structure and aerodynamic performance. Their commercialization, however, still encounters many challenges. A series of studies were conducted in the current research to improve the VAWTs design and enhance their aerodynamic performance. First, an efficient design methodology built on an existing analytical approach is presented to formulate the design parameters influencing a straight bladed-VAWT (SB-VAWT) aerodynamic performance and determine the optimal range of these parameters for prototype construction. This work was followed by a series of studies to collectively investigate the role of external turbulence on the SB-VAWTs operation. The external free-stream turbulence is known as one of the most important factors influencing VAWTs since this type of turbines is mainly considered for urban applications where the wind turbulence is of great significance. Initially, two sets of wind tunnel testing were conducted to study the variation of aerodynamic performance of a SB-VAWT's blade under turbulent flows, in two major stationary configurations, namely two- and three-dimensional flows. Turbulent flows generated in the wind tunnel were quasi-isotropic having uniform mean flow profiles, free of any wind shear effects. Aerodynamic force measurements demonstrated that the free-stream turbulence improves the blade aerodynamic performance in stall and post-stall regions by delaying the stall and increasing the lift-to-drag ratio. After these studies, a SB-VAWT model was tested in the wind tunnel under the same type of turbulent flows. The turbine power output was substantially increased in the presence of the grid turbulence at the same wind speeds, while the increase in turbine power coefficient due to the effect of grid turbulence was small at the same tip speed ratios. The final section presents an experimental study on the aerodynamic interaction of VAWTs in arrays

High-Fidelity Aerodynamic Shape Optimization for Natural Laminar Flow

NASA Astrophysics Data System (ADS)

Rashad, Ramy

To ensure the long-term sustainability of aviation, serious effort is underway to mitigate the escalating economic, environmental, and social concerns of the industry. Significant improvement to the energy efficiency of air transportation is required through the research and development of advanced and unconventional airframe and engine technologies. In the quest to reduce airframe drag, this thesis is concerned with the development and demonstration of an effective design tool for improving the aerodynamic efficiency of subsonic and transonic airfoils. The objective is to advance the state-of-the-art in high-fidelity aerodynamic shape optimization by incorporating and exploiting the phenomenon of laminar-turbulent transition in an efficient manner. A framework for the design and optimization of Natural Laminar Flow (NLF) airfoils is developed and demonstrated with transition prediction capable of accounting for the effects of Reynolds number, freestream turbulence intensity, Mach number, and pressure gradients. First, a two-dimensional Reynolds-averaged Navier-Stokes (RANS) flow solver has been extended to incorporate an iterative laminar-turbulent transition prediction methodology. The natural transition locations due to Tollmien-Schlichting instabilities are predicted using the simplified eN envelope method of Drela and Giles or, alternatively, the compressible form of the Arnal-Habiballah-Delcourt criterion. The boundary-layer properties are obtained directly from the Navier-Stokes flow solution, and the transition to turbulent flow is modeled using an intermittency function in conjunction with the Spalart-Allmaras turbulence model. The RANS solver is subsequently employed in a gradient-based sequential quadratic programming shape optimization framework. The laminar-turbulent transition criteria are tightly coupled into the objective and gradient evaluations. The gradients are obtained using a new augmented discrete-adjoint formulation for non-local transition

Effects of differential and symmetrical aileron deflection on the aerodynamic characteristics of an NASA supercritical-wing research airplane model

NASA Technical Reports Server (NTRS)

Bartlett, D. W.

1975-01-01

An investigation has been conducted in the Langley 8 foot transonic pressure tunnel to determine the effects of differential and symmetrical aileron deflection on the longitudinal and lateral directional aerodynamic characteristics of an 0.087 scale model of an NASA supercritical wing research airplane (TF-8A). Tests were conducted at Mach numbers from 0.25 to 0.99 in order to determine the effects of differential aileron deflection and at Mach numbers of 0.25 and 0.50 to determine the effects of symmetrical aileron (flap) deflection. The angle of attack range for all tests varied from approximately -12 deg to 20 deg.

Turbine blade unsteady aerodynamic loading and heat transfer

NASA Astrophysics Data System (ADS)

Johnston, David Alan

Stator indexing to minimize the unsteady aerodynamic loading of closely spaced airfoil rows in turbomachinery is a new technique for the passive control of flow-induced vibrations. This technique, along with the effects of steady blade loading, were studied by means of experiments performed in a two-stage low-speed research turbine. With the second vane row fixed, the inlet vane row was indexed to six positions over one vane-pitch cycle for a range of stage loadings. The aerodynamic forcing function to the first-stage rotor was measured in the rotating reference frame, with the resulting rotor blade unsteady aerodynamic response quantified by rotor blades instrumented with dynamic pressure transducers. Reductions in the unsteady lift magnitude were achieved at all turbine operating conditions, with attenuation ranging from 37% to 74% of the maximum unsteady lift. Additionally, in complementary experiments, the effects of stator indexing and steady blade loading on the unsteady heat transfer of the first- and second-stage rotors was studied for the design and highest blade loading conditions using platinum-film heat gages. The attenuation of unsteady heat transfer coefficient was blade-loading dependent and location dependent along the chord and span, ranging 10% to 90% of maximum. Due to the high degree of location dependence of attenuation, stator indexing is therefore best suited to minimize unsteady heat transfer in local hot spots of the blade rather than the blade as a whole.

Aerodynamic shape optimization using control theory

NASA Technical Reports Server (NTRS)

Reuther, James

1996-01-01

Aerodynamic shape design has long persisted as a difficult scientific challenge due its highly nonlinear flow physics and daunting geometric complexity. However, with the emergence of Computational Fluid Dynamics (CFD) it has become possible to make accurate predictions of flows which are not dominated by viscous effects. It is thus worthwhile to explore the extension of CFD methods for flow analysis to the treatment of aerodynamic shape design. Two new aerodynamic shape design methods are developed which combine existing CFD technology, optimal control theory, and numerical optimization techniques. Flow analysis methods for the potential flow equation and the Euler equations form the basis of the two respective design methods. In each case, optimal control theory is used to derive the adjoint differential equations, the solution of which provides the necessary gradient information to a numerical optimization method much more efficiently then by conventional finite differencing. Each technique uses a quasi-Newton numerical optimization algorithm to drive an aerodynamic objective function toward a minimum. An analytic grid perturbation method is developed to modify body fitted meshes to accommodate shape changes during the design process. Both Hicks-Henne perturbation functions and B-spline control points are explored as suitable design variables. The new methods prove to be computationally efficient and robust, and can be used for practical airfoil design including geometric and aerodynamic constraints. Objective functions are chosen to allow both inverse design to a target pressure distribution and wave drag minimization. Several design cases are presented for each method illustrating its practicality and efficiency. These include non-lifting and lifting airfoils operating at both subsonic and transonic conditions.

Identifying research priorities for health care priority setting: a collaborative effort between managers and researchers

PubMed Central

Smith, Neale; Mitton, Craig; Peacock, Stuart; Cornelissen, Evelyn; MacLeod, Stuart

2009-01-01

Background To date there has been relatively little published about how research priorities are set, and even less about methods by which decision-makers can be engaged in defining a relevant and appropriate research agenda. We report on a recent effort in British Columbia to have researchers and decision-makers jointly establish an agenda for future research into questions of resource allocation. Methods The researchers enlisted decision-maker partners from each of British Columbia's six health authorities. Three forums were held, at which researchers and decision-makers from various levels in the health authorities considered possible research areas related to three key focus areas: (1) generation and use of decision criteria and measurement of 'benefit' against such criteria; (2) identification of so-called 'disinvestment' opportunities; and (3) evaluation of the effectiveness of priority setting procedures. Detailed notes were taken from each forum and synthesized into a set of qualitative themes. Results Forum participants suggested that future research into healthcare priority setting would benefit from studies that were longitudinal, comparative, and/or interdisciplinary. As well, participants identified two broad theme areas in which specific research projects were deemed desirable. First, future research might usefully consider how formal priority setting and resource allocation projects are situated within a larger organizational and political context. Second, additional research efforts should be devoted to better understanding and improving the actual implementation of priority setting frameworks, particularly with respect to issues of change management and the resolution of impediments to action on recommendations for resource allocation. Conclusion We were able to validate the importance of initial areas posed to the group and observed emergence of additional concerns and directions of critical importance to these decision-makers at this time. It is

The aerodynamics of running socks: Reality or rhetoric?

PubMed

Ashford, Robert L; White, Peter; Indramohan, Vivek

2011-12-01

The primary objective of this study was to test the aerodynamic properties of a selection of running and general sports socks. Eleven pairs of socks were tested in a specially constructed rig which was inserted into a fully calibrated wind tunnel. Wind test speeds included 3, 4, 5, 6, 12 and 45m/s. There was no significant difference between any of the socks tested for their aerodynamic properties. The drag coefficients calculated for each sock varied proportionally with the Reynolds number. No particular sock was more aerodynamic than any of the socks tested. There is no evidence that a sock that is "aerodynamically designed" will help an athlete go faster. This may be more product rhetoric than reality, and further work is justified if such claims are being made. Copyright © 2011 Elsevier Ltd. All rights reserved.

A Generic Nonlinear Aerodynamic Model for Aircraft

NASA Technical Reports Server (NTRS)

Grauer, Jared A.; Morelli, Eugene A.

2014-01-01

A generic model of the aerodynamic coefficients was developed using wind tunnel databases for eight different aircraft and multivariate orthogonal functions. For each database and each coefficient, models were determined using polynomials expanded about the state and control variables, and an othgonalization procedure. A predicted squared-error criterion was used to automatically select the model terms. Modeling terms picked in at least half of the analyses, which totalled 45 terms, were retained to form the generic nonlinear aerodynamic (GNA) model. Least squares was then used to estimate the model parameters and associated uncertainty that best fit the GNA model to each database. Nonlinear flight simulations were used to demonstrate that the GNA model produces accurate trim solutions, local behavior (modal frequencies and damping ratios), and global dynamic behavior (91% accurate state histories and 80% accurate aerodynamic coefficient histories) under large-amplitude excitation. This compact aerodynamics model can be used to decrease on-board memory storage requirements, quickly change conceptual aircraft models, provide smooth analytical functions for control and optimization applications, and facilitate real-time parametric system identification.

Efficient Global Aerodynamic Modeling from Flight Data

NASA Technical Reports Server (NTRS)

Morelli, Eugene A.

2012-01-01

A method for identifying global aerodynamic models from flight data in an efficient manner is explained and demonstrated. A novel experiment design technique was used to obtain dynamic flight data over a range of flight conditions with a single flight maneuver. Multivariate polynomials and polynomial splines were used with orthogonalization techniques and statistical modeling metrics to synthesize global nonlinear aerodynamic models directly and completely from flight data alone. Simulation data and flight data from a subscale twin-engine jet transport aircraft were used to demonstrate the techniques. Results showed that global multivariate nonlinear aerodynamic dependencies could be accurately identified using flight data from a single maneuver. Flight-derived global aerodynamic model structures, model parameter estimates, and associated uncertainties were provided for all six nondimensional force and moment coefficients for the test aircraft. These models were combined with a propulsion model identified from engine ground test data to produce a high-fidelity nonlinear flight simulation very efficiently. Prediction testing using a multi-axis maneuver showed that the identified global model accurately predicted aircraft responses.

Basis Function Approximation of Transonic Aerodynamic Influence Coefficient Matrix

NASA Technical Reports Server (NTRS)

Li, Wesley W.; Pak, Chan-gi

2011-01-01

A technique for approximating the modal aerodynamic influence coefficients matrices by using basis functions has been developed and validated. An application of the resulting approximated modal aerodynamic influence coefficients matrix for a flutter analysis in transonic speed regime has been demonstrated. This methodology can be applied to the unsteady subsonic, transonic, and supersonic aerodynamics. The method requires the unsteady aerodynamics in frequency-domain. The flutter solution can be found by the classic methods, such as rational function approximation, k, p-k, p, root-locus et cetera. The unsteady aeroelastic analysis for design optimization using unsteady transonic aerodynamic approximation is being demonstrated using the ZAERO flutter solver (ZONA Technology Incorporated, Scottsdale, Arizona). The technique presented has been shown to offer consistent flutter speed prediction on an aerostructures test wing 2 configuration with negligible loss in precision in transonic speed regime. These results may have practical significance in the analysis of aircraft aeroelastic calculation and could lead to a more efficient design optimization cycle.

Australian Aerodynamic Design Codes for Aerial Tow Bodies.

DTIC Science & Technology

1987-08-27

HTP -1, which deals with aerial targets, it was recognised that there was a need for a complete and well docL mented approach for their aerodynamic and...circular cables cannot be assessed with the programs in their present form. 10. none of the programs are well documented and user’s manuals are not...National Leader ANL TTCP HTP -1 Weapons Systems Research Laboratory Director Superintendent - Weapons Division - Combat Systems Division Navy Office Navy

The influence of flight style on the aerodynamic properties of avian wings as fixed lifting surfaces

PubMed Central

Dimitriadis, Grigorios; Nudds, Robert L.

2016-01-01

The diversity of wing morphologies in birds reflects their variety of flight styles and the associated aerodynamic and inertial requirements. Although the aerodynamics underlying wing morphology can be informed by aeronautical research, important differences exist between planes and birds. In particular, birds operate at lower, transitional Reynolds numbers than do most aircraft. To date, few quantitative studies have investigated the aerodynamic performance of avian wings as fixed lifting surfaces and none have focused upon the differences between wings from different flight style groups. Dried wings from 10 bird species representing three distinct flight style groups were mounted on a force/torque sensor within a wind tunnel in order to test the hypothesis that wing morphologies associated with different flight styles exhibit different aerodynamic properties. Morphological differences manifested primarily as differences in drag rather than lift. Maximum lift coefficients did not differ between groups, whereas minimum drag coefficients were lowest in undulating flyers (Corvids). The lift to drag ratios were lower than in conventional aerofoils and data from free-flying soaring species; particularly in high frequency, flapping flyers (Anseriformes), which do not rely heavily on glide performance. The results illustrate important aerodynamic differences between the wings of different flight style groups that cannot be explained solely by simple wing-shape measures. Taken at face value, the results also suggest that wing-shape is linked principally to changes in aerodynamic drag, but, of course, it is aerodynamics during flapping and not gliding that is likely to be the primary driver. PMID:27781155

Aerodynamics and Optimal Design of Biplane Wind Turbine Blades

NASA Astrophysics Data System (ADS)

Chiu, Phillip

In order to improve energy capture and reduce the cost of wind energy, in the past few decades wind turbines have grown significantly larger. As their blades get longer, the design of the inboard region (near the blade root) becomes a trade-off between competing structural and aerodynamic requirements. State-of-the-art blades require thick airfoils near the root to efficiently support large loads inboard, but those thick airfoils have inherently poor aerodynamic performance. New designs are required to circumvent this design compromise. One such design is the "biplane blade", in which the thick airfoils in the inboard region are replaced with thinner airfoils in a biplane configuration. This design was shown previously to have significantly increased structural performance over conventional blades. In addition, the biplane airfoils can provide increased lift and aerodynamic efficiency compared to thick monoplane inboard airfoils, indicating a potential for increased power extraction. This work investigates the fundamental aerodynamic aspects, aerodynamic design and performance, and optimal structural design of the biplane blade. First, the two-dimensional aerodynamics of biplanes with relatively thick airfoils are investigated, showing unique phenomena which arise as a result of airfoil thickness. Next, the aerodynamic design of the full biplane blade is considered. Two biplane blades are designed for optimal aerodynamic loading, and their aerodynamic performance quantified. Considering blades with practical chord distributions and including the drag of the mid-blade joint, it is shown that biplane blades have comparable power output to conventional monoplane designs. The results of this analysis also show that the biplane blades can be designed with significantly less chord than conventional designs, a characteristic which enables larger blade designs. The aerodynamic loads on the biplane blades are shown to be increased in gust conditions and decreased under

A New Compendium of Unsteady Aerodynamic Test Cases for CFD: Summary of AVT WG-003 Activities

NASA Technical Reports Server (NTRS)

Ruiz-Calavera, Luis P.; Bennett, Robert; Fox, John H.; Galbraith, Robert W.; Geurts, Evert; Henshaw, Micahel J. deC.; Huang, XingZhong; Kaynes, Ian W.; Loeser, Thomas; Naudin, Pierre;

Ground/Flight Correlation of Aerodynamic Loads with Structural Response

NASA Technical Reports Server (NTRS)

Mangalam, Arun S.; Davis, Mark C.

2009-01-01

Ground and flight tests provide a basis and methodology for in-flight characterization of the aerodynamic and structural performance through the monitoring of the fluid-structure interaction. The NF-15B flight tests of the Intelligent Flight Control System program provided a unique opportunity to test the correlation of aerodynamic loads with points of flow attaching and detaching from the surface, which are also known as flow bifurcation points, as observed in a previous wind tunnel test performed at the U.S. Air Force Academy (Colorado Springs, Colorado). Moreover, flight tests, along with the subsequent unsteady aerodynamic tests in the NASA Transonic Dynamics Tunnel (TDT), provide a basis using surface flow sensors as means of assessing the aeroelastic performance of flight vehicles. For the flight tests, the NF-15B tail was instrumented with hot-film sensors and strain gages for measuring root-bending strains. This data were gathered via selected sideslip maneuvers performed at level flight and subsonic speeds. The aerodynamic loads generated by the sideslip maneuver resulted in a structural response, which were then compared with the hot-film sensor signals. The hot-film sensor signals near the stagnation region were found to be highly correlated with the root-bending strains. For the TDT tests, a flexible wing section developed under the U.S. Air Force Research Lab SensorCraft program was instrumented with strain gages, accelerometers, and hot-film sensors at two span stations. The TDT tests confirmed the correlation between flow bifurcation points and the wing structural response to tunnel-generated gusts. Furthermore, as the wings structural modes were excited by the gusts, a gradual phase change between the flow bifurcation point and the structural mode occurred during a resonant condition.

The Aerodynamics of Deforming Wings at Low Reynolds Number

NASA Astrophysics Data System (ADS)

Medina, Albert

Flapping flight has gained much attention in the past decade driven by the desire to understand capabilities observed in nature and the desire to develop agile small-scale aerial vehicles. Advancing our current understanding of unsteady aerodynamics is an essential component in the development of micro-air vehicles (MAV) intended to utilize flight mechanics akin to insect flight. Thus the efforts undertaken that of bio-mimicry. The complexities of insect wing motion are dissected and simplified to more tractable problems to elucidate the fundamentals of unsteady aerodynamics in biologically inspired kinematics. The MAV's fruition would satisfy long established needs in both the military and civilian sectors. Although recent studies have provided great insight into the lift generating mechanisms of flapping wings the deflection response of such wings remains poorly understood. This dissertation numerically and experimentally investigates the aerodynamic performance of passively and actively deflected wings in hover and rotary kinematics. Flexibility is distilled to discrete lines of flexion which acknowledging major flexion lines in insect wings to be the primary avenue for deformation. Of primary concern is the development of the leading-edge vortex (LEV), a high circulation region of low pressure above the wing to which much of the wing's lift generation is attributed. Two-dimensional simulations of wings with chord-wise flexibility in a freestream reveal a lift generating mechanism unavailable to rigid wings with origins in vortical symmetry breaking. The inclusion of flexibility in translating wings accelerated from rest revealed the formation time of the initial LEV was very weakly dependent on the flexible stiffness of the wing, maintaining a universal time scale of four to five chords of travel before shedding. The frequency of oscillatory shedding of the leading and trailing-edge vortices that develops after the initial vortex shedding was shown to be

Forced response analysis of an aerodynamically detuned supersonic turbomachine rotor

NASA Technical Reports Server (NTRS)

Hoyniak, D.; Fleeter, S.

1985-01-01

High performance aircraft-engine fan and compressor blades are vulnerable to aerodynamically forced vibrations generated by inlet flow distortions due to wakes from upstream blade and vane rows, atmospheric gusts, and maldistributions in inlet ducts. In this report, an analysis is developed to predict the flow-induced forced response of an aerodynamically detuned rotor operating in a supersonic flow with a subsonic axial component. The aerodynamic detuning is achieved by alternating the circumferential spacing of adjacent rotor blades. The total unsteady aerodynamic loading acting on the blading, as a result of the convection of the transverse gust past the airfoil cascade and the resulting motion of the cascade, is developed in terms of influence coefficients. This analysis is used to investigate the effect of aerodynamic detuning on the forced response of a 12-blade rotor, with Verdon's Cascade B flow geometry as a uniformly spaced baseline configuration. The results of this study indicate that, for forward traveling wave gust excitations, aerodynamic detuning is very beneficial, resulting in significantly decreased maximum-amplitude blade responses for many interblade phase angles.

Numerical study on aerodynamic damping of floating vertical axis wind turbines

NASA Astrophysics Data System (ADS)

Cheng, Zhengshun; Aagaard Madsen, Helge; Gao, Zhen; Moan, Torgeir

2016-09-01

Harvesting offshore wind energy resources using floating vertical axis wind turbines (VAWTs) has attracted an increasing interest in recent years. Due to its potential impact on fatigue damage, the aerodynamic damping should be considered in the preliminary design of a floating VAWT based on the frequency domain method. However, currently the study on aerodynamic damping of floating VAWTs is very limited. Due to the essential difference in aerodynamic load characteristics, the aerodynamic damping of a floating VAWT could be different from that of a floating horizontal axis wind turbine (HAWT). In this study, the aerodynamic damping of floating VAWTs was studied in a fully coupled manner, and its influential factors and its effects on the motions, especially the pitch motion, were demonstrated. Three straight-bladed floating VAWTs with identical solidity and with a blade number varying from two to four were considered. The aerodynamic damping under steady and turbulent wind conditions were estimated using fully coupled aero-hydro-servo-elastic time domain simulations. It is found that the aerodynamic damping ratio of the considered floating VAWTs ranges from 1.8% to 5.3%. Moreover, the aerodynamic damping is almost independent of the rotor azimuth angle, and is to some extent sensitive to the blade number.

Analysis of Aerodynamic Load of LSU-03 (LAPAN Surveillance UAV-03) Propeller

NASA Astrophysics Data System (ADS)

Rahmadi Nuranto, Awang; Jamaludin Fitroh, Ahmad; Syamsudin, Hendri

2018-04-01

The existing propeller of the LSU-03 aircraft is made of wood. To improve structural strength and obtain better mechanical properties, the propeller will be redesigned usingcomposite materials. It is necessary to simulate and analyze the design load. This research paper explainsthe simulation and analysis of aerodynamic load prior to structural design phase of composite propeller. Aerodynamic load calculations are performed using both the Blade Element Theory(BET) and the Computational Fluid Dynamic (CFD)simulation. The result of both methods show a close agreement, the different thrust forces is only 1.2 and 4.1% for two type mesh. Thus the distribution of aerodynamic loads along the surface of the propeller blades of the 3-D CFD simulation results are considered valid and ready to design the composite structure. TheCFD results is directly imported to the structure model using the Direct Import CFD / One-Way Fluid Structure Interaction (FSI) method. Design load of propeller is chosen at the flight condition at speed of 20 km/h at 7000 rpm.

Enthalpy By Energy Balance for Aerodynamic Heating Facility at NASA Ames Research Center Arc Jet Complex

NASA Technical Reports Server (NTRS)

Hightower, T. Mark; MacDonald, Christine L.; Martinez, Edward R.; Balboni, John A.; Anderson, Karl F.; Arnold, Jim O. (Technical Monitor)

2002-01-01

The NASA Ames Research Center (ARC) Arc Jet Facilities' Aerodynamic Heating Facility (AHF) has been instrumented for the Enthalpy By Energy Balance (EB2) method. Diagnostic EB2 data is routinely taken for all AHF runs. This paper provides an overview of the EB2 method implemented in the AHF. The chief advantage of the AHF implementation over earlier versions is the non-intrusiveness of the instruments used. For example, to measure the change in cooling water temperature, thin film 1000 ohm Resistance Temperature Detectors (RTDs) are used with an Anderson Current Loop (ACL) as the signal conditioner. The ACL with 1000 ohm RTDs allows for very sensitive measurement of the increase in temperature (Delta T) of the cooling water to the arc heater, which is a critical element of the EB2 method. Cooling water flow rates are measured with non-intrusive ultrasonic flow meters.

Aerodynamic Analysis of the Truss-Braced Wing Aircraft Using Vortex-Lattice Superposition Approach

NASA Technical Reports Server (NTRS)

Ting, Eric Bi-Wen; Reynolds, Kevin Wayne; Nguyen, Nhan T.; Totah, Joseph J.

2014-01-01

The SUGAR Truss-BracedWing (TBW) aircraft concept is a Boeing-developed N+3 aircraft configuration funded by NASA ARMD FixedWing Project. This future generation transport aircraft concept is designed to be aerodynamically efficient by employing a high aspect ratio wing design. The aspect ratio of the TBW is on the order of 14 which is significantly greater than those of current generation transport aircraft. This paper presents a recent aerodynamic analysis of the TBW aircraft using a conceptual vortex-lattice aerodynamic tool VORLAX and an aerodynamic superposition approach. Based on the underlying linear potential flow theory, the principle of aerodynamic superposition is leveraged to deal with the complex aerodynamic configuration of the TBW. By decomposing the full configuration of the TBW into individual aerodynamic lifting components, the total aerodynamic characteristics of the full configuration can be estimated from the contributions of the individual components. The aerodynamic superposition approach shows excellent agreement with CFD results computed by FUN3D, USM3D, and STAR-CCM+.

Aerodynamic Reconstruction Applied to Parachute Test Vehicle Flight Data Analysis

NASA Technical Reports Server (NTRS)

Cassady, Leonard D.; Ray, Eric S.; Truong, Tuan H.

2013-01-01

The aerodynamics, both static and dynamic, of a test vehicle are critical to determining the performance of the parachute cluster in a drop test and for conducting a successful test. The Capsule Parachute Assembly System (CPAS) project is conducting tests of NASA's Orion Multi-Purpose Crew Vehicle (MPCV) parachutes at the Army Yuma Proving Ground utilizing the Parachute Test Vehicle (PTV). The PTV shape is based on the MPCV, but the height has been reduced in order to fit within the C-17 aircraft for extraction. Therefore, the aerodynamics of the PTV are similar, but not the same as, the MPCV. A small series of wind tunnel tests and computational fluid dynamics cases were run to modify the MPCV aerodynamic database for the PTV, but aerodynamic reconstruction of the flights has proven an effective source for further improvements to the database. The acceleration and rotational rates measured during free flight, before parachute inflation but during deployment, were used to con rm vehicle static aerodynamics. A multibody simulation is utilized to reconstruct the parachute portions of the flight. Aerodynamic or parachute parameters are adjusted in the simulation until the prediction reasonably matches the flight trajectory. Knowledge of the static aerodynamics is critical in the CPAS project because the parachute riser load measurements are scaled based on forebody drag. PTV dynamic damping is critical because the vehicle has no reaction control system to maintain attitude - the vehicle dynamics must be understood and modeled correctly before flight. It will be shown here that aerodynamic reconstruction has successfully contributed to the CPAS project.

GLOBAL CHANGE RESEARCH NEWS #10: MULTIAGENCY, MULTINATIONAL GLOBAL CHANGE RESEARCH EFFORT IN THE UPPER SAN PEDRO BASIN

EPA Science Inventory

This edition reports on a multiagency, multinational global-change research effort that seeks to evaluate the consequences of natural and human-induced changes in semi-arid environments. The Semi-Arid Land-Surface-Atmosphere Program ("SALSA") is focused on the environmentally sen...

Current status of computational methods for transonic unsteady aerodynamics and aeroelastic applications

NASA Technical Reports Server (NTRS)

Edwards, John W.; Malone, John B.

1992-01-01

The current status of computational methods for unsteady aerodynamics and aeroelasticity is reviewed. The key features of challenging aeroelastic applications are discussed in terms of the flowfield state: low-angle high speed flows and high-angle vortex-dominated flows. The critical role played by viscous effects in determining aeroelastic stability for conditions of incipient flow separation is stressed. The need for a variety of flow modeling tools, from linear formulations to implementations of the Navier-Stokes equations, is emphasized. Estimates of computer run times for flutter calculations using several computational methods are given. Applications of these methods for unsteady aerodynamic and transonic flutter calculations for airfoils, wings, and configurations are summarized. Finally, recommendations are made concerning future research directions.

The Oxford Probe: an open access five-hole probe for aerodynamic measurements

NASA Astrophysics Data System (ADS)

Hall, B. F.; Povey, T.

2017-03-01

The Oxford Probe is an open access five-hole probe designed for experimental aerodynamic measurements. The open access probe can be manufactured by the end user via additive manufacturing (metal or plastic). The probe geometry, drawings, calibration maps, and software are available under a creative commons license. The purpose is to widen access to aerodynamic measurement techniques in education and research environments. There are many situations in which the open access probe will allow results of comparable accuracy to a well-calibrated commercial probe. We discuss the applications and limitations of the probe, and compare the calibration maps for 16 probes manufactured in different materials and at different scales, but with the same geometrical design.

Physics of badminton shuttlecocks. Part 1 : aerodynamics

NASA Astrophysics Data System (ADS)

Cohen, Caroline; Darbois Texier, Baptiste; Quéré, David; Clanet, Christophe

2011-11-01

We study experimentally shuttlecocks dynamics. In this part we show that shuttlecock trajectory is highly different from classical parabola. When one takes into account the aerodynamic drag, the flight of the shuttlecock quickly curves downwards and almost reaches a vertical asymptote. We solve the equation of motion with gravity and drag at high Reynolds number and find an analytical expression of the reach. At high velocity, this reach does not depend on velocity anymore. Even if you develop your muscles you will not manage to launch the shuttlecock very far because of the ``aerodynamic wall.'' As a consequence you can predict the length of the field. We then discuss the extend of the aerodynamic wall to other projectiles like sports balls and its importance.

CFD based aerodynamic modeling to study flight dynamics of a flapping wing micro air vehicle

NASA Astrophysics Data System (ADS)

Rege, Alok Ashok

The demand for small unmanned air vehicles, commonly termed micro air vehicles or MAV's, is rapidly increasing. Driven by applications ranging from civil search-and-rescue missions to military surveillance missions, there is a rising level of interest and investment in better vehicle designs, and miniaturized components are enabling many rapid advances. The need to better understand fundamental aspects of flight for small vehicles has spawned a surge in high quality research in the area of micro air vehicles. These aircraft have a set of constraints which are, in many ways, considerably different from that of traditional aircraft and are often best addressed by a multidisciplinary approach. Fast-response non-linear controls, nano-structures, integrated propulsion and lift mechanisms, highly flexible structures, and low Reynolds aerodynamics are just a few of the important considerations which may be combined in the execution of MAV research. The main objective of this thesis is to derive a consistent nonlinear dynamic model to study the flight dynamics of micro air vehicles with a reasonably accurate representation of aerodynamic forces and moments. The research is divided into two sections. In the first section, derivation of the nonlinear dynamics of flapping wing micro air vehicles is presented. The flapping wing micro air vehicle (MAV) used in this research is modeled as a system of three rigid bodies: a body and two wings. The design is based on an insect called Drosophila Melanogaster, commonly known as fruit-fly. The mass and inertial effects of the wing on the body are neglected for the present work. The nonlinear dynamics is simulated with the aerodynamic data published in the open literature. The flapping frequency is used as the control input. Simulations are run for different cases of wing positions and the chosen parameters are studied for boundedness. Results show a qualitative inconsistency in boundedness for some cases, and demand a better

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.

Influence of Different Diffuser Angle on Sedan's Aerodynamic Characteristics

NASA Astrophysics Data System (ADS)

Hu, Xingjun; Zhang, Rui; Ye, Jian; Yan, Xu; Zhao, Zhiming

The aerodynamic characteristics have a great influence on the fuel economics and the steering stability of a high speed vehicle. The underbody rear diffuser is one of important aerodynamic add-on devices. The parameters of the diffuser, including the diffuser angle, the number and the shape of separators, the shape of the end plate and etc, will affect the underbody flow and the wake. Here, just the influence of the diffuser angle was investigated without separator and the end plate. The method of Computational Fluid Dynamics was adopted to study the aerodynamic characteristics of a simplified sedan with a different diffuser angle respectively. The diffuser angle was set to 0°, 3°, 6°, 9.8° and 12° respectively. The diffuser angle of the original model is 9.8°. The conclusions were drawn that when the diffuser angle increases, the underbody flow and especially the wake change greatly and the pressure change correspondingly; as a result, the total aerodynamic drag coefficients of car first decrease and then increases, while the total aerodynamic lift coefficients decrease.

Future fundamental combustion research for aeropropulsion systems

NASA Technical Reports Server (NTRS)

Mularz, E. J.

1985-01-01

Physical fluid mechanics, heat transfer, and chemical kinetic processes which occur in the combustion chamber of aeropropulsion systems were investigated. With the component requirements becoming more severe for future engines, the current design methodology needs the new tools to obtain the optimum configuration in a reasonable design and development cycle. Research efforts in the last few years were encouraging but to achieve these benefits research is required into the fundamental aerothermodynamic processes of combustion. It is recommended that research continues in the areas of flame stabilization, combustor aerodynamics, heat transfer, multiphase flow and atomization, turbulent reacting flows, and chemical kinetics. Associated with each of these engineering sciences is the need for research into computational methods to accurately describe and predict these complex physical processes. Research needs in each of these areas are highlighted.

A Basic Experiment on the Aerodynamics of Sniffing

NASA Astrophysics Data System (ADS)

Settles, Gary S.; Kester, Douglas A.

1999-11-01

Our previous work (APS/DFD97:Ii1 and 98:FA10) used flow visualization to observe canine olfaction. The results raised some basic questions about the aerodynamics of sniffing, e.g. what flow rate is required, as a function of distance from a scent source, to acquire a detectable scent? Commercial sampler technology does not address such questions. A basic experiment was thus designed to investigate the aerodynamic phenomena and performance of sniffing. A stable thermal layer on a horizontal plane was used as a "scent" source per Reynolds Analogy. The detector was a thermocouple inside a sniffer tube. Flow patterns were observed by schlieren. Results show the importance of sniffer proximity to localize a scent source. A transient scent spike occurs at the sniff onset, followed by signal decline due to source depletion. Sniffing shows extreme sensitivity to disruptive air currents. Unstably-stratified scent sources (thermal plumes) are also considered. These results help us understand evolved sniffing behavior, and they suggest sampler design criteria for electronic-nose devices. (Research supported by DARPA.)

Full-envelope aerodynamic modeling of the Harrier aircraft

NASA Technical Reports Server (NTRS)

Mcnally, B. David

1986-01-01

A project to identify a full-envelope model of the YAV-8B Harrier using flight-test and parameter identification techniques is described. As part of the research in advanced control and display concepts for V/STOL aircraft, a full-envelope aerodynamic model of the Harrier is identified, using mathematical model structures and parameter identification methods. A global-polynomial model structure is also used as a basis for the identification of the YAV-8B aerodynamic model. State estimation methods are used to ensure flight data consistency prior to parameter identification.Equation-error methods are used to identify model parameters. A fixed-base simulator is used extensively to develop flight test procedures and to validate parameter identification software. Using simple flight maneuvers, a simulated data set was created covering the YAV-8B flight envelope from about 0.3 to 0.7 Mach and about -5 to 15 deg angle of attack. A singular value decomposition implementation of the equation-error approach produced good parameter estimates based on this simulated data set.

Shuttle ascent and shock impingement aerodynamic heating studies

NASA Technical Reports Server (NTRS)

Lanning, W. D.; Hung, F. T.

1971-01-01

The collection and analysis of aerodynamic heating data obtained from shock impingement experimental investigation were completed. The data were categorized into four interference areas; fin leading edge, wing/fuselage fin/plate corners, and space shuttle configurations. The effects of shock impingement were found to increase the heating rates 10 to 40 times the undisturbed values. A test program was completed at NASA/Langley Research Center to investigate the magnitudes and surface patterns of the mated shock interference flowfield. A 0.0065 scale thin-skin model of the MDAC 256-20 space shuttle booster mated with a Stycast model of the MDAC Internal tank orbiter was tested in the 20-inch M=6 tunnel, the 31-inch M=10 tunnel, and the 48-inch Unitary Plan Tunnel. The gap region of the ascent configuration was the principal area of interest where both thermocouple and phase-change paint data were obtained. Pressure and heat transfer distributions data on the leeward surface of a 75-degree sweep slab delta wing are presented. The effects of surface roughness on boundary layer transition and aerodynamic heating were investigated.

Aerodynamic analysis of an isolated vehicle wheel

NASA Astrophysics Data System (ADS)

Leśniewicz, P.; Kulak, M.; Karczewski, M.

2014-08-01

Increasing fuel prices force the manufacturers to look into all aspects of car aerodynamics including wheels, tyres and rims in order to minimize their drag. By diminishing the aerodynamic drag of vehicle the fuel consumption will decrease, while driving safety and comfort will improve. In order to properly illustrate the impact of a rotating wheel aerodynamics on the car body, precise analysis of an isolated wheel should be performed beforehand. In order to represent wheel rotation in contact with the ground, presented CFD simulations included Moving Wall boundary as well as Multiple Reference Frame should be performed. Sliding mesh approach is favoured but too costly at the moment. Global and local flow quantities obtained during simulations were compared to an experiment in order to assess the validity of the numerical model. Results of investigation illustrates dependency between type of simulation and coefficients (drag and lift). MRF approach proved to be a better solution giving result closer to experiment. Investigation of the model with contact area between the wheel and the ground helps to illustrate the impact of rotating wheel aerodynamics on the car body.

Unsteady Aerodynamic Model Tuning for Precise Flutter Prediction

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi

2011-01-01

A simple method for an unsteady aerodynamic model tuning is proposed in this study. This method is based on the direct modification of the aerodynamic influence coefficient matrices. The aerostructures test wing 2 flight-test data is used to demonstrate the proposed model tuning method. The flutter speed margin computed using only the test validated structural dynamic model can be improved using the additional unsteady aerodynamic model tuning, and then the flutter speed margin requirement of 15 % in military specifications can apply towards the test validated aeroelastic model. In this study, unsteady aerodynamic model tunings are performed at two time invariant flight conditions, at Mach numbers of 0.390 and 0.456. When the Mach number for the unsteady model tuning approaches to the measured fluttering Mach number, 0.502, at the flight altitude of 9,837 ft, the estimated flutter speed is approached to the measured flutter speed at this altitude. The minimum flutter speed difference between the estimated and measured flutter speed is -.14 %.

Quasi-steady state aerodynamics of the cheetah tail

PubMed Central

Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily

2016-01-01

ABSTRACT During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities. PMID:27412267

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.

Phonatory aerodynamics in connected speech.

PubMed

Gartner-Schmidt, Jackie L; Hirai, Ryoji; Dastolfo, Christina; Rosen, Clark A; Yu, Lan; Gillespie, Amanda I

2015-12-01

1) Present phonatory aerodynamic data for healthy controls (HCs) in connected speech; 2) contrast these findings between HCs and patients with nontreated unilateral vocal fold paralysis (UVFP); 3) present pre- and post-vocal fold augmentation outcomes for patients with UVFP; 4) contrast data from patients with post-operative laryngeal augmentation to HCs. Retrospective, single-blinded. For phase I, 20 HC participants were recruited. For phase II, 20 patients with UVFP were age- and gender-matched to the 20 HC participants used in phase I. For phase III, 20 patients with UVFP represented a pre- and posttreatment cohort. For phase IV, 20 of the HC participants from phase I and 20 of the postoperative UVFP patients from phase III were used for direct comparison. Aerodynamic measures captured from a sample of the Rainbow Passage included: number of breaths, mean phonatory airflow rate, total duration of passage, inspiratory airflow duration, and expiratory airflow duration. The VHI-10 was also obtained pre- and postoperative laryngeal augmentation. All phonatory aerodynamic measures were significantly increased in patients with preoperative UVFP than the HC group. Patients with laryngeal augmentation took significantly less breaths, had less mean phonatory airflow rate during voicing, and had shorter inspiratory airflow duration than the preoperative UVFP group. None of the postoperative measures returned to HC values. Significant improvement in the Voice Handicap Index-10 scores postlaryngeal augmentation was also found. Methodology described in this study improves upon existing aerodynamic voice assessment by capturing characteristics germane to UVFP patient complaints and measuring change before and after laryngeal augmentation in connected speech. 4. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Aerodynamic Design Study of Advanced Multistage Axial Compressor

NASA Technical Reports Server (NTRS)

Larosiliere, Louis M.; Wood, Jerry R.; Hathaway, Michael D.; Medd, Adam J.; Dang, Thong Q.

2002-01-01

As a direct response to the need for further performance gains from current multistage axial compressors, an investigation of advanced aerodynamic design concepts that will lead to compact, high-efficiency, and wide-operability configurations is being pursued. Part I of this report describes the projected level of technical advancement relative to the state of the art and quantifies it in terms of basic aerodynamic technology elements of current design systems. A rational enhancement of these elements is shown to lead to a substantial expansion of the design and operability space. Aerodynamic design considerations for a four-stage core compressor intended to serve as a vehicle to develop, integrate, and demonstrate aerotechnology advancements are discussed. This design is biased toward high efficiency at high loading. Three-dimensional blading and spanwise tailoring of vector diagrams guided by computational fluid dynamics (CFD) are used to manage the aerodynamics of the high-loaded endwall regions. Certain deleterious flow features, such as leakage-vortex-dominated endwall flow and strong shock-boundary-layer interactions, were identified and targeted for improvement. However, the preliminary results were encouraging and the front two stages were extracted for further aerodynamic trimming using a three-dimensional inverse design method described in part II of this report. The benefits of the inverse design method are illustrated by developing an appropriate pressure-loading strategy for transonic blading and applying it to reblade the rotors in the front two stages of the four-stage configuration. Multistage CFD simulations based on the average passage formulation indicated an overall efficiency potential far exceeding current practice for the front two stages. Results of the CFD simulation at the aerodynamic design point are interrogated to identify areas requiring additional development. In spite of the significantly higher aerodynamic loadings, advanced CFD

Active Aerodynamic Load Reduction on a Rotorcraft Fuselage With Rotor Effects: A CFD Validation Effort

NASA Technical Reports Server (NTRS)

Allan, Brian G.; Schaeffler, Norman W.; Jenkins, Luther N.; Yao, Chung-Sheng; Wong, Oliver D.; Tanner, Philip E.

2015-01-01

A rotorcraft fuselage is typically designed with an emphasis on operational functionality with aerodynamic efficiency being of secondary importance. This results in a significant amount of drag during high-speed forward flight that can be a limiting factor for future high-speed rotorcraft designs. To enable higher speed flight, while maintaining a functional fuselage design (i.e., a large rear cargo ramp door), the NASA Rotary Wing Project has conducted both experimental and computational investigations to assess active flow control as an enabling technology for fuselage drag reduction. This paper will evaluate numerical simulations of a flow control system on a generic rotorcraft fuselage with a rotor in forward flight using OVERFLOW, a structured mesh Reynolds-averaged Navier-Stokes flow solver developed at NASA. The results are compared to fuselage forces, surface pressures, and PN flow field data obtained in a wind tunnel experiment conducted at the NASA Langley 14-by 22-Foot Subsonic Tunnel where significant drag and download reductions were demonstrated using flow control. This comparison showed that the Reynolds-averaged Navier-Stokes flow solver was unable to predict the fuselage forces and pressure measurements on the ramp for the baseline and flow control cases. While the CFD was able to capture the flow features, it was unable to accurately predict the performance of the flow control.

Announcing a Community Effort to Create an Information Model for Research Software Archives

NASA Astrophysics Data System (ADS)

Million, C.; Brazier, A.; King, T.; Hayes, A.

2018-04-01

An effort has started to create recommendations and standards for the archiving of planetary science research software. The primary goal is to define an information model that is consistent with OAIS standards.

New Horizons Launch Contingency Effort

NASA Astrophysics Data System (ADS)

Chang, Yale; Lear, Matthew H.; McGrath, Brian E.; Heyler, Gene A.; Takashima, Naruhisa; Owings, W. Donald

2007-01-01

On 19 January 2006 at 2:00 PM EST, the NASA New Horizons spacecraft (SC) was launched from the Cape Canaveral Air Force Station (CCAFS), FL, onboard an Atlas V 551/Centaur/STAR™ 48B launch vehicle (LV) on a mission to explore the Pluto Charon planetary system and possibly other Kuiper Belt Objects. It carried a single Radioisotope Thermoelectric Generator (RTG). As part of the joint NASA/US Department of Energy (DOE) safety effort, contingency plans were prepared to address the unlikely events of launch accidents leading to a near-pad impact, a suborbital reentry, an orbital reentry, or a heliocentric orbit. As the implementing organization. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) had expanded roles in the New Horizons launch contingency effort over those for the Cassini mission and Mars Exploration Rovers missions. The expanded tasks included participation in the Radiological Control Center (RADCC) at the Kennedy Space Center (KSC), preparation of contingency plans, coordination of space tracking assets, improved aerodynamics characterization of the RTG's 18 General Purpose Heat Source (GPHS) modules, and development of spacecraft and RTG reentry breakup analysis tools. Other JHU/APL tasks were prediction of the Earth impact footprints (ElFs) for the GPHS modules released during the atmospheric reentry (for purposes of notification and recovery), prediction of the time of SC reentry from a potential orbital decay, pre-launch dissemination of ballistic coefficients of various possible reentry configurations, and launch support of an Emergency Operations Center (EOC) on the JHU/APL campus. For the New Horizons launch, JHU/APL personnel at the RADCC and at the EOC were ready to implement any real-time launch contingency activities. A successful New Horizons launch and interplanetary injection precluded any further contingency actions. The New Horizons launch contingency was an interagency effort by several organizations. This paper

The Nozzle Acoustic Test Rig: an Acoustic and Aerodynamic Free-jet Facility

NASA Technical Reports Server (NTRS)

Castner, Raymond S.

1994-01-01

The nozzle acoustic test rig (NATR) was built at NASA Lewis Research Center to support the High Speed Research Program. The facility is capable of measuring the acoustic and aerodynamic performance of aircraft engine nozzle concepts. Trade-off studies are conducted to compare performance and noise during simulated low-speed flight and takeoff. Located inside an acoustically treated dome with a 62-ft radius, the NATR is a free-jet that has a 53-in. diameter and is driven by an air ejector. This ejector is operated with 125 lb/s of compressed air, at 125 psig, to achieve 375 lb/s at Mach 0.3. Acoustic and aerodynamic data are collected from test nozzles mounted in the free-jet flow. The dome serves to protect the surrounding community from high noise levels generated by the nozzles, and to provide an anechoic environment for acoustic measurements. Information presented in this report summarizes free-jet performance, fluid support systems, and data acquisition capabilities of the NATR.

Quasi steady-state aerodynamic model development for race vehicle simulations

NASA Astrophysics Data System (ADS)

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

2016-01-01

Presented in this paper is a procedure to develop a high fidelity quasi steady-state aerodynamic model for use in race car vehicle dynamic simulations. Developed to fit quasi steady-state wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady-state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This same procedure can be extended to the other five aerodynamic degrees of freedom to develop a complete six degree of freedom quasi steady-state aerodynamic model for any vehicle.

On the formulation of the aerodynamic characteristics in aircraft dynamics

NASA Technical Reports Server (NTRS)

Tobak, M.; Schiff, L. B.

1976-01-01

The theory of functionals is used to reformulate the notions of aerodynamic indicial functions and superposition. Integral forms for the aerodynamic response to arbitrary motions are derived that are free of dependence on a linearity assumption. Simplifications of the integral forms lead to practicable nonlinear generalizations of the linear superpositions and stability derivative formulations. Applied to arbitrary nonplanar motions, the generalization yields a form for the aerodynamic response that can be compounded of the contributions from a limited number of well-defined characteristic motions, in principle reproducible in the wind tunnel. Further generalizations that would enable the consideration of random fluctuations and multivalued aerodynamic responses are indicated.

Mathematical modeling of the aerodynamics of high-angle-of-attack maneuvers

NASA Technical Reports Server (NTRS)

Schiff, L. B.; Tobak, M.; Malcolm, G. N.

1980-01-01

This paper is a review of the current state of aerodynamic mathematical modeling for aircraft motions at high angles of attack. The mathematical model serves to define a set of characteristic motions from whose known aerodynamic responses the aerodynamic response to an arbitrary high angle-of-attack flight maneuver can be predicted. Means are explored of obtaining stability parameter information in terms of the characteristic motions, whether by wind-tunnel experiments, computational methods, or by parameter-identification methods applied to flight-test data. A rationale is presented for selecting and verifying the aerodynamic mathematical model at the lowest necessary level of complexity. Experimental results describing the wing-rock phenomenon are shown to be accommodated within the most recent mathematical model by admitting the existence of aerodynamic hysteresis in the steady-state variation of the rolling moment with roll angle. Interpretation of the experimental results in terms of bifurcation theory reveals the general conditions under which aerodynamic hysteresis must exist.

Adjoint-Based Aerodynamic Design of Complex Aerospace Configurations

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.

2016-01-01

An overview of twenty years of adjoint-based aerodynamic design research at NASA Langley Research Center is presented. Adjoint-based algorithms provide a powerful tool for efficient sensitivity analysis of complex large-scale computational fluid dynamics (CFD) simulations. Unlike alternative approaches for which computational expense generally scales with the number of design parameters, adjoint techniques yield sensitivity derivatives of a simulation output with respect to all input parameters at the cost of a single additional simulation. With modern large-scale CFD applications often requiring millions of compute hours for a single analysis, the efficiency afforded by adjoint methods is critical in realizing a computationally tractable design optimization capability for such applications.

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

PubMed Central

Nakata, Toshiyuki; Liu, Hao

2012-01-01

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. PMID:21831896

Aerodynamic Shape Sensitivity Analysis and Design Optimization of Complex Configurations Using Unstructured Grids

NASA Technical Reports Server (NTRS)

Taylor, Arthur C., III; Newman, James C., III; Barnwell, Richard W.

1997-01-01

A three-dimensional unstructured grid approach to aerodynamic shape sensitivity analysis and design optimization has been developed and is extended to model geometrically complex configurations. The advantage of unstructured grids (when compared with a structured-grid approach) is their inherent ability to discretize irregularly shaped domains with greater efficiency and less effort. Hence, this approach is ideally suited for geometrically complex configurations of practical interest. In this work the nonlinear Euler equations are solved using an upwind, cell-centered, finite-volume scheme. The discrete, linearized systems which result from this scheme are solved iteratively by a preconditioned conjugate-gradient-like algorithm known as GMRES for the two-dimensional geometry and a Gauss-Seidel algorithm for the three-dimensional; similar procedures are used to solve the accompanying linear aerodynamic sensitivity equations in incremental iterative form. As shown, this particular form of the sensitivity equation makes large-scale gradient-based aerodynamic optimization possible by taking advantage of memory efficient methods to construct exact Jacobian matrix-vector products. Simple parameterization techniques are utilized for demonstrative purposes. Once the surface has been deformed, the unstructured grid is adapted by considering the mesh as a system of interconnected springs. Grid sensitivities are obtained by differentiating the surface parameterization and the grid adaptation algorithms with ADIFOR (which is an advanced automatic-differentiation software tool). To demonstrate the ability of this procedure to analyze and design complex configurations of practical interest, the sensitivity analysis and shape optimization has been performed for a two-dimensional high-lift multielement airfoil and for a three-dimensional Boeing 747-200 aircraft.

Integrated Aerodynamic/Structural/Dynamic Analyses of Aircraft with Large Shape Changes

NASA Technical Reports Server (NTRS)

Samareh, Jamshid A.; Chwalowski, Pawel; Horta, Lucas G.; Piatak, David J.; McGowan, Anna-Maria R.

2007-01-01

The conceptual and preliminary design processes for aircraft with large shape changes are generally difficult and time-consuming, and the processes are often customized for a specific shape change concept to streamline the vehicle design effort. Accordingly, several existing reports show excellent results of assessing a particular shape change concept or perturbations of a concept. The goal of the current effort was to develop a multidisciplinary analysis tool and process that would enable an aircraft designer to assess several very different morphing concepts early in the design phase and yet obtain second-order performance results so that design decisions can be made with better confidence. The approach uses an efficient parametric model formulation that allows automatic model generation for systems undergoing radical shape changes as a function of aerodynamic parameters, geometry parameters, and shape change parameters. In contrast to other more self-contained approaches, the approach utilizes off-the-shelf analysis modules to reduce development time and to make it accessible to many users. Because the analysis is loosely coupled, discipline modules like a multibody code can be easily swapped for other modules with similar capabilities. One of the advantages of this loosely coupled system is the ability to use the medium-to high-fidelity tools early in the design stages when the information can significantly influence and improve overall vehicle design. Data transfer among the analysis modules are based on an accurate and automated general purpose data transfer tool. In general, setup time for the integrated system presented in this paper is 2-4 days for simple shape change concepts and 1-2 weeks for more mechanically complicated concepts. Some of the key elements briefly described in the paper include parametric model development, aerodynamic database generation, multibody analysis, and the required software modules as well as examples for a telescoping wing, a

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.

Tools for 3D scientific visualization in computational aerodynamics

NASA Technical Reports Server (NTRS)

Bancroft, Gordon; Plessel, Todd; Merritt, Fergus; Watson, Val

1989-01-01

The purpose is to describe the tools and techniques in use at the NASA Ames Research Center for performing visualization of computational aerodynamics, for example visualization of flow fields from computer simulations of fluid dynamics about vehicles such as the Space Shuttle. The hardware used for visualization is a high-performance graphics workstation connected to a super computer with a high speed channel. At present, the workstation is a Silicon Graphics IRIS 3130, the supercomputer is a CRAY2, and the high speed channel is a hyperchannel. The three techniques used for visualization are post-processing, tracking, and steering. Post-processing analysis is done after the simulation. Tracking analysis is done during a simulation but is not interactive, whereas steering analysis involves modifying the simulation interactively during the simulation. Using post-processing methods, a flow simulation is executed on a supercomputer and, after the simulation is complete, the results of the simulation are processed for viewing. The software in use and under development at NASA Ames Research Center for performing these types of tasks in computational aerodynamics is described. Workstation performance issues, benchmarking, and high-performance networks for this purpose are also discussed as well as descriptions of other hardware for digital video and film recording.

Predictions of Aerodynamic Heating on Tactical Missile Domes

DTIC Science & Technology

1979-04-25

A . Martellucci W. Daskin J. D. Cresswell J. B. Arnaiz L. A . Marshall J. Cassanto R. Hobbs C. Harris F. George P.O. Box 8555 Philadelphia, PA J9101... A LEVELs NSWC TR 79-21 i PREDICTIONS OF AERODYNAMIC HEATING ON TACTICAL MISSILE DOMES A wo BY T. F. ZIEN W. C. RAGSDALE RESEARCH TECHNOLOGY...DOMES SAUTHOR( a ) 8. CONTRACT OR GRANT NUMBER() T. F. ZiendW.C jRagsale 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT. TASK

Viscous-Inviscid Methods in Unsteady Aerodynamic Analysis of Bio-Inspired Morphing Wings

NASA Astrophysics Data System (ADS)

Dhruv, Akash V.

Flight has been one of the greatest realizations of human imagination, revolutionizing communication and transportation over the years. This has greatly influenced the growth of technology itself, enabling researchers to communicate and share their ideas more effectively, extending the human potential to create more sophisticated systems. While the end product of a sophisticated technology makes our lives easier, its development process presents an array of challenges in itself. In last decade, scientists and engineers have turned towards bio-inspiration to design more efficient and robust aerodynamic systems to enhance the ability of Unmanned Aerial Vehicles (UAVs) to be operated in cluttered environments, where tight maneuverability and controllability are necessary. Effective use of UAVs in domestic airspace will mark the beginning of a new age in communication and transportation. The design of such complex systems necessitates the need for faster and more effective tools to perform preliminary investigations in design, thereby streamlining the design process. This thesis explores the implementation of numerical panel methods for aerodynamic analysis of bio-inspired morphing wings. Numerical panel methods have been one of the earliest forms of computational methods for aerodynamic analysis to be developed. Although the early editions of this method performed only inviscid analysis, the algorithm has matured over the years as a result of contributions made by prominent aerodynamicists. The method discussed in this thesis is influenced by recent advancements in panel methods and incorporates both viscous and inviscid analysis of multi-flap wings. The surface calculation of aerodynamic coefficients makes this method less computationally expensive than traditional Computational Fluid Dynamics (CFD) solvers available, and thus is effective when both speed and accuracy are desired. The morphing wing design, which consists of sequential feather-like flaps installed

Design of control laws for flutter suppression based on the aerodynamic energy concept and comparisons with other design methods

NASA Technical Reports Server (NTRS)

Nissim, Eli

1990-01-01

The aerodynamic energy method is used to synthesize control laws for NASA's drone for aerodynamic and structural testing-aerodynamic research wing 1 (DAST-ARW1) mathematical model. The performance of these control laws in terms of closed-loop flutter dynamic pressure, control surface activity, and robustness is compared with other control laws that relate to the same model. A control law synthesis technique that makes use of the return difference singular values is developed. It is based on the aerodynamic energy approach and is shown to yield results that are superior to those results given in the literature and are based on optimal control theory. Nyquist plots are presented, together with a short discussion regarding the relative merits of the minimum singular value as a measure of robustness as compared with the more traditional measure involving phase and gain margins.

Influence of yaw on propeller aerodynamic characteristics

NASA Astrophysics Data System (ADS)

Nguyen, Van Bang; Rozehnal, Dalibor; Hnidka, Jakub; Pham, Vu Uy

2018-06-01

Between the propeller axis and free stream direction, it can still be a non-zero yaw angle. This paper introduces some propeller experiments, in which the propeller aerodynamic characteristics have been determined in various yaw angle and different rotational speeds. The experimental aerodynamic characteristics are acquired dynamic values, from which the influence of yaw conditions on the frequency and the amplitude of propeller thrust and torque can be obtained.

Aeroservoelastic and Structural Dynamics Research on Smart Structures Conducted at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

McGowan, Anna-Maria Rivas; Wilkie, W. Keats; Moses, Robert W.; Lake, Renee C.; Florance, Jennifer Pinkerton; Wieseman, Carol D.; Reaves, Mercedes C.; Taleghani, Barmac K.; Mirick, Paul H.; Wilbur, Mathew L.

1997-01-01

An overview of smart structures research currently underway at the NASA Langley Research Center in the areas of aeroservoelasticity and structural dynamics is presented. Analytical and experimental results, plans, potential technology pay-offs, and challenges are discussed. The goal of this research is to develop the enabling technologies to actively and passively control aircraft and rotorcraft vibration and loads using smart devices. These enabling technologies and related research efforts include developing experimentally-validated finite element and aeroservoelastic modeling techniques; conducting bench experimental tests to assess feasibility and understand system trade-offs; and conducting large-scale wind tunnel tests to demonstrate system performance. The key aeroservoelastic applications of this research include: active twist control of rotor blades using interdigitated electrode piezoelectric composites and active control of flutter, and gust and buffeting responses using discrete piezoelectric patches. In addition, NASA Langley is an active participant in the DARPA/Air Force Research Laboratory/NASA/Northrop Grumman Smart Wing program which is assessing aerodynamic performance benefits using smart materials.

Overview of Supersonic Aerodynamics Measurement Techniques in the NASA Langley Unitary Plan Wind Tunnel

NASA Technical Reports Server (NTRS)

Erickson, Gary E.

2007-01-01

An overview is given of selected measurement techniques used in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) to determine the aerodynamic characteristics of aerospace vehicles operating at supersonic speeds. A broad definition of a measurement technique is adopted in this paper and is any qualitative or quantitative experimental approach that provides information leading to the improved understanding of the supersonic aerodynamic characteristics. On-surface and off-surface measurement techniques used to obtain discrete (point) and global (field) measurements and planar and global flow visualizations are described, and examples of all methods are included. The discussion is limited to recent experiences in the UPWT and is, therefore, not an exhaustive review of existing experimental techniques. The diversity and high quality of the measurement techniques and the resultant data illustrate the capabilities of a ground-based experimental facility and the key role that it plays in the advancement of our understanding, prediction, and control of supersonic aerodynamics.

Exploring the Aerodynamic Drag of a Moving Cyclist

ERIC Educational Resources Information Center

Theilmann, Florian; Reinhard, Christopher

2016-01-01

Although the physics of cycling itself is a complex mixture of aerodynamics, physiology, mechanics, and heuristics, using cycling as a context for teaching physics has a tradition of certainly more than 30 years. Here, a possible feature is the discussion of the noticeable resistant forces such as aerodynamic drag and the associated power…

An Investigation of the Aerodynamics and Cooling of a Horizontally-Opposed Engine Installation

NASA Technical Reports Server (NTRS)

Miley, S. J.

1977-01-01

A research program to investigate the aerodynamics of reciprocating aircraft engine cooling installations is discussed. Current results from a flight test program are presented concerning installation flow measurement methods. The influence of different inlet designs on installation cooling effectiveness and efficiency are described.

The interference aerodynamics caused by the wing elasticity during store separation

NASA Astrophysics Data System (ADS)

Lei, Yang; Zheng-yin, Ye

2016-04-01

Air-launch-to-orbit is the technology that has stores carried aloft and launched the store from the plane to the orbit. The separation between the aircraft and store is one of the most important and difficult phases in air-launch-to-orbit technology. There exists strong aerodynamic interference between the aircraft and the store in store separation. When the aspect ratio of the aircraft is large, the elastic deformations of the wing must be considered. The main purpose of this article is to study the influence of the interference aerodynamics caused by the elastic deformations of the wing to the unsteady aerodynamics of the store. By solving the coupled functions of unsteady Navier-Stokes equations, six degrees of freedom dynamic equations and structural dynamic equations simultaneously, the store separation with the elastic deformation of the aircraft considered is simulated numerically. And the interactive aerodynamic forces are analyzed. The study shows that the interference aerodynamics is obvious at earlier time during the separation, and the dominant frequency of the elastic wing determines the aerodynamic forces frequencies of the store. Because of the effect of the interference aerodynamics, the roll angle response and pitch angle response increase. When the store is mounted under the wingtip, the additional aerodynamics caused by the wingtip vortex is obvious, which accelerate the divergence of the lateral force and the lateral-directional attitude angle of the store. This study supports some beneficial conclusions to the engineering application of the air-launch-to-orbit.

Survey of research on unsteady aerodynamic loading of delta wings

NASA Technical Reports Server (NTRS)

Ashley, H.; Vaneck, T.; Katz, J.; Jarrah, M. A.

1991-01-01

For aeronautical applications, there has been recent interest in accurately determining the aerodynamic forces and moments experienced by low-aspect-ratio wings performing transient maneuvers which go to angles of attack as high as 90 deg. Focusing on the delta planform with sharp leading edges, the paper surveys experimental and theoretical investigations dealing with the associated unsteady flow phenomena. For maximum angles above a value between 30 and 40 deg, flow details and airloads are dominated by hysteresis in the 'bursting' instability of intense vortices which emanate from the leading edge. As examples of relevant test results, force and moment histories are presented for a model series with aspect ratios 1, 1.5 and 2. Influences of key parameters are discussed, notably those which measure unsteadiness. Comparisons are given with two theories: a paneling approximation that cannot capture bursting but clarifies other unsteady influences, and a simplified estimation scheme which uses measured bursting data.

The shouted voice: A pilot study of laryngeal physiology under extreme aerodynamic pressure.

PubMed

Lagier, Aude; Legou, Thierry; Galant, Camille; Amy de La Bretèque, Benoit; Meynadier, Yohann; Giovanni, Antoine

2017-12-01

The objective was to study the behavior of the larynx during shouted voice production, when the larynx is exposed to extremely high subglottic pressure. The study involved electroglottographic, acoustic, and aerodynamic analyses of shouts produced at maximum effort by three male participants. Under a normal speaking voice, the voice sound pressure level (SPL) is proportional to the subglottic pressure. However, when the subglottic pressure reached high levels, the voice SPL reached a maximum value and then decreased as subglottic pressure increased further. Furthermore, the electroglottographic signal sometimes lost its periodicity during the shout, suggesting irregular vocal fold vibration.

Bibliography of Supersonic Cruise Aircraft Research (SCAR) Program from 1972 to Mid-1977

NASA Technical Reports Server (NTRS)

Hoffman, S.

1977-01-01

This bibliography documents publications of the supersonic cruise aircraft research (SCAR) program that were generated during the first 5 years of effort. The reports are arranged according to systems studies and five SCAR disciplines: propulsion, stratospheric emissions impact, structures and materials, aerodynamic performance, and stability and control. The specific objectives of each discipline are summarized. Annotation is included for all NASA inhouse and low-number contractor reports. There are 444 papers and articles included.

System Identification and POD Method Applied to Unsteady Aerodynamics

NASA Technical Reports Server (NTRS)

Tang, Deman; Kholodar, Denis; Juang, Jer-Nan; Dowell, Earl H.

2001-01-01

The representation of unsteady aerodynamic flow fields in terms of global aerodynamic modes has proven to be a useful method for reducing the size of the aerodynamic model over those representations that use local variables at discrete grid points in the flow field. Eigenmodes and Proper Orthogonal Decomposition (POD) modes have been used for this purpose with good effect. This suggests that system identification models may also be used to represent the aerodynamic flow field. Implicit in the use of a systems identification technique is the notion that a relative small state space model can be useful in describing a dynamical system. The POD model is first used to show that indeed a reduced order model can be obtained from a much larger numerical aerodynamical model (the vortex lattice method is used for illustrative purposes) and the results from the POD and the system identification methods are then compared. For the example considered, the two methods are shown to give comparable results in terms of accuracy and reduced model size. The advantages and limitations of each approach are briefly discussed. Both appear promising and complementary in their characteristics.

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.

Aerodynamic Effects and Modeling of Damage to Transport Aircraft

NASA Technical Reports Server (NTRS)

Shah, Gautam H.

2008-01-01

A wind tunnel investigation was conducted to measure the aerodynamic effects of damage to lifting and stability/control surfaces of a commercial transport aircraft configuration. The modeling of such effects is necessary for the development of flight control systems to recover aircraft from adverse, damage-related loss-of-control events, as well as for the estimation of aerodynamic characteristics from flight data under such conditions. Damage in the form of partial or total loss of area was applied to the wing, horizontal tail, and vertical tail. Aerodynamic stability and control implications of damage to each surface are presented, to aid in the identification of potential boundaries in recoverable stability or control degradation. The aerodynamic modeling issues raised by the wind tunnel results are discussed, particularly the additional modeling requirements necessitated by asymmetries due to damage, and the potential benefits of such expanded modeling.

Computational Aerodynamic Analysis of Offshore Upwind and Downwind Turbines

DOE PAGES

Zhao, Qiuying; Sheng, Chunhua; Afjeh, Abdollah

2014-01-01

Aerodynamic interactions of the model NREL 5 MW offshore horizontal axis wind turbines (HAWT) are investigated using a high-fidelity computational fluid dynamics (CFD) analysis. Four wind turbine configurations are considered; three-bladed upwind and downwind and two-bladed upwind and downwind configurations, which operate at two different rotor speeds of 12.1 and 16 RPM. In the present study, both steady and unsteady aerodynamic loads, such as the rotor torque, blade hub bending moment, and base the tower bending moment of the tower, are evaluated in detail to provide overall assessment of different wind turbine configurations. Aerodynamic interactions between the rotor and tower are analyzed,more » including the rotor wake development downstream. The computational analysis provides insight into aerodynamic performance of the upwind and downwind, two- and three-bladed horizontal axis wind turbines.« less

Wind turbine design codes: A preliminary comparison of the aerodynamics

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

Buhl, M.L. Jr.; Wright, A.D.; Tangler, J.L.

1997-12-01

The National Wind Technology Center of the National Renewable Energy Laboratory is comparing several computer codes used to design and analyze wind turbines. The first part of this comparison is to determine how well the programs predict the aerodynamic behavior of turbines with no structural degrees of freedom. Without general agreement on the aerodynamics, it is futile to try to compare the structural response due to the aerodynamic input. In this paper, the authors compare the aerodynamic loads for three programs: Garrad Hassan`s BLADED, their own WT-PERF, and the University of Utah`s YawDyn. This report documents a work in progressmore » and compares only two-bladed, downwind turbines.« less

Identification of aerodynamic models for maneuvering aircraft

NASA Technical Reports Server (NTRS)

Chin, Suei; Lan, C. Edward

1990-01-01

Due to the requirement of increased performance and maneuverability, the flight envelope of a modern fighter is frequently extended to the high angle-of-attack regime. Vehicles maneuvering in this regime are subjected to nonlinear aerodynamic loads. The nonlinearities are due mainly to three-dimensional separated flow and concentrated vortex flow that occur at large angles of attack. Accurate prediction of these nonlinear airloads is of great importance in the analysis of a vehicle's flight motion and in the design of its flight control system. A satisfactory evaluation of the performance envelope of the aircraft may require a large number of coupled computations, one for each change in initial conditions. To avoid the disadvantage of solving the coupled flow-field equations and aircraft's motion equations, an alternate approach is to use a mathematical modeling to describe the steady and unsteady aerodynamics for the aircraft equations of motion. Aerodynamic forces and moments acting on a rapidly maneuvering aircraft are, in general, nonlinear functions of motion variables, their time rate of change, and the history of maneuvering. A numerical method was developed to analyze the nonlinear and time-dependent aerodynamic response to establish the generalized indicial function in terms of motion variables and their time rates of change.

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.

Identification of aerodynamic models for maneuvering aircraft

NASA Technical Reports Server (NTRS)

Lan, C. Edward; Hu, C. C.

1992-01-01

A Fourier analysis method was developed to analyze harmonic forced-oscillation data at high angles of attack as functions of the angle of attack and its time rate of change. The resulting aerodynamic responses at different frequencies are used to build up the aerodynamic models involving time integrals of the indicial type. An efficient numerical method was also developed to evaluate these time integrals for arbitrary motions based on a concept of equivalent harmonic motion. The method was verified by first using results from two-dimensional and three-dimensional linear theories. The developed models for C sub L, C sub D, and C sub M based on high-alpha data for a 70 deg delta wing in harmonic motions showed accurate results in reproducing hysteresis. The aerodynamic models are further verified by comparing with test data using ramp-type motions.

Quasi-steady state aerodynamics of the cheetah tail.

PubMed

Patel, Amir; Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily

2016-08-15

During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities. © 2016. Published by The Company of Biologists Ltd.

Application of Approximate Unsteady Aerodynamics for Flutter Analysis

NASA Technical Reports Server (NTRS)

Pak, Chan-gi; Li, Wesley W.

2010-01-01

A technique for approximating the modal aerodynamic influence coefficient (AIC) matrices by using basis functions has been developed. A process for using the resulting approximated modal AIC matrix in aeroelastic analysis has also been developed. The method requires the unsteady aerodynamics in frequency domain, and this methodology can be applied to the unsteady subsonic, transonic, and supersonic aerodynamics. The flutter solution can be found by the classic methods, such as rational function approximation, k, p-k, p, root locus et cetera. The unsteady aeroelastic analysis using unsteady subsonic aerodynamic approximation is demonstrated herein. The technique presented is shown to offer consistent flutter speed prediction on an aerostructures test wing (ATW) 2 and a hybrid wing body (HWB) type of vehicle configuration with negligible loss in precision. This method computes AICs that are functions of the changing parameters being studied and are generated within minutes of CPU time instead of hours. These results may have practical application in parametric flutter analyses as well as more efficient multidisciplinary design and optimization studies.

Modeling the Launch Abort Vehicle's Subsonic Aerodynamics from Free Flight Testing

NASA Technical Reports Server (NTRS)

Hartman, Christopher L.

2010-01-01

An investigation into the aerodynamics of the Launch Abort Vehicle for NASA's Constellation Crew Launch Vehicle in the subsonic, incompressible flow regime was conducted in the NASA Langley 20-ft Vertical Spin Tunnel. Time histories of center of mass position and Euler Angles are captured using photogrammetry. Time histories of the wind tunnel's airspeed and dynamic pressure are recorded as well. The primary objective of the investigation is to determine models for the aerodynamic yaw and pitch moments that provide insight into the static and dynamic stability of the vehicle. System IDentification Programs for AirCraft (SIDPAC) is used to determine the aerodynamic model structure and estimate model parameters. Aerodynamic models for the aerodynamic body Y and Z force coefficients, and the pitching and yawing moment coefficients were identified.

NASA/Army Rotorcraft Technology. Volume 1: Aerodynamics, and Dynamics and Aeroelasticity

NASA Technical Reports Server (NTRS)

1988-01-01

The Conference Proceedings is a compilation of over 30 technical papers presented at this milestone event which reported on the advances in rotorcraft technical knowledge resulting from NASA, Army, and industry rotorcraft research programs over the last 5 to 10 years. The Conference brought together over 230 government, industry, and allied nation conferees to exchange technical information and hear invited technical papers by prominent NASA, Army, and industry researchers covering technology topics which included: aerodynamics, dynamics and elasticity, propulsion and drive systems, flight dynamics and control, acoustics, systems integration, and research aircraft.

Aerodynamic characteristics of some lifting reentry concepts applicable to transatmospheric vehicle design studies

NASA Technical Reports Server (NTRS)

Spearman, M. L.

1984-01-01

The aerodynamic characteristics of some lifting reentry concepts are examined with a view to the applicability of such concepts to the design of possible transatmospheric vehicles (TAV). A considerable amount of research has been done in past years with vehicle concepts suitable for manned atmospheric-entry, atmospheric flight, and landing. Some of the features of these concepts that permit flight in or out of the atmosphere with maneuver capability should be useful in the mission requirements of TAV's. The concepts illustrated include some hypersonic-body shapes with and without variable geometry surfaces, and a blunt lifting-body configuration. The merits of these concepts relative to the aerodynamic behavior of a TAV are discussed.

A Reduced-Complexity Investigation of Blunt Leading-Edge Separation Motivated by UCAV Aerodynamics

NASA Technical Reports Server (NTRS)

Luckring, James M.; Boelens, Okko J.

2015-01-01

A reduced complexity investigation for blunt-leading-edge vortical separation has been undertaken. The overall approach is to design the fundamental work in such a way so that it relates to the aerodynamics of a more complex Uninhabited Combat Air Vehicle (UCAV) concept known as SACCON. Some of the challenges associated with both the vehicle-class aerodynamics and the fundamental vortical flows are reviewed, and principles from a hierarchical complexity approach are used to relate flow fundamentals to system-level interests. The work is part of roughly 6-year research program on blunt-leading-edge separation pertinent to UCAVs, and was conducted under the NATO Science and Technology Organization, Applied Vehicle Technology panel.

Multidisciplinary Computational Aerodynamics

DTIC Science & Technology

2013-10-01

flat plate. These wings exhibit large aspect ratio and a highly corrugated structure. Several wind tunnel studies have shown possible advantages...Advances in Turbines Aero-thermo-mechanical Design and Analysis”, IGT Institute, Vancouver, June 2011 Rizzetta: Invited Seminar, University of...pressure turbines for high- altitude aircraft, distributed-roughness transition, flapping wing aerodynamics and laser turrets. Flow Structure and Unsteady

Aerodynamics of the pseudo-glottis.

PubMed

Kotby, M N; Hegazi, M A; Kamal, I; Gamal El Dien, N; Nassar, J

2009-01-01

The aim of this work is to study the hitherto unclear aerodynamic parameters of the pseudo-glottis following total laryngectomy. These parameters include airflow rate, sub-pseudo-glottic pressure (SubPsG), efficiency and resistance, as well as sound pressure level (SPL). Eighteen male patients who have undergone total laryngectomy, with an age range from 54 to 72 years, were investigated in this study. All tested patients were fluent esophageal 'voice' speakers utilizing tracheo-esophageal prosthesis. The airflow rate, SubPsG and SPL were measured. The results showed that the mean value of the airflow rate was 53 ml/s, the SubPsG pressure was 13 cm H(2)O, while the SPL was 66 dB. The normative data obtained from the true glottis in healthy age-matched subjects are 89 ml/s, 7.9 cm H(2)O and 70 dB, respectively. Other aerodynamic indices were calculated and compared to the data obtained from the true glottis. Such a comparison of the pseudo-glottic aerodynamic data to the data of the true glottis gives an insight into the mechanism of action of the pseudo-glottis. The data obtained suggests possible clinical applications in pseudo-voice training. Copyright 2009 S. Karger AG, Basel.

Application of CAD/CAE class systems to aerodynamic analysis of electric race cars

NASA Astrophysics Data System (ADS)

Grabowski, L.; Baier, A.; Buchacz, A.; Majzner, M.; Sobek, M.

2015-11-01

Aerodynamics is one of the most important factors which influence on every aspect of a design of a car and car driving parameters. The biggest influence aerodynamics has on design of a shape of a race car body, especially when the main objective of the race is the longest distance driven in period of time, which can not be achieved without low energy consumption and low drag of a car. Designing shape of the vehicle body that must generate the lowest possible drag force, without compromising the other parameters of the drive. In the article entitled „Application of CAD/CAE class systems to aerodynamic analysis of electric race cars” are being presented problems solved by computer analysis of cars aerodynamics and free form modelling. Analysis have been subjected to existing race car of a Silesian Greenpower Race Team. On a basis of results of analysis of existence of Kammback aerodynamic effect innovative car body were modeled. Afterwards aerodynamic analysis were performed to verify existence of aerodynamic effect for innovative shape and to recognize aerodynamics parameters of the shape. Analysis results in the values of coefficients and aerodynamic drag forces. The resulting drag forces Fx, drag coefficients Cx(Cd) and aerodynamic factors Cx*A allowed to compare all of the shapes to each other. Pressure distribution, air velocities and streams courses were useful in determining aerodynamic features of analyzed shape. For aerodynamic tests was used Ansys Fluent CFD software. In a paper the ways of surface modeling with usage of Realize Shape module and classic surface modeling were presented. For shapes modeling Siemens NX 9.0 software was used. Obtained results were used to estimation of existing shapes and to make appropriate conclusions.

Engineering Aerodynamics

DTIC Science & Technology

1986-12-01

effective Reynolds Number5 to include the effet Of turbulence, which was supported in a convincing manner by the same ratio of 2.4 betwveen the Reynolds...iLIFT DEVICIS 143 methods incorl)orating various forms of flas) are shown on Figure 59. The other two methods, Boundary Layer Control and the Magnus ...Class Airship Hlull with Varying Lengths of Cylindric Midships," N.A.CA. Technical Report No. 138 (1922). 276 ENGINEERING AERODYNAMICS [Ch. 9 -- - - 2.0

Laser Technology in Aerodynamic Measurements.

DTIC Science & Technology

holography; Laser beam probing for aerodynamic flow field analysis; The laser in high speed photography; Laser metrology; Application of duel scatter laser doppler velocimeters for wind tunnel measurements.

Flow-Visualization Techniques Used at High Speed by Configuration Aerodynamics Wind-Tunnel-Test Team

NASA Technical Reports Server (NTRS)

Lamar, John E. (Editor)

2001-01-01

This paper summarizes a variety of optically based flow-visualization techniques used for high-speed research by the Configuration Aerodynamics Wind-Tunnel Test Team of the High-Speed Research Program during its tenure. The work of other national experts is included for completeness. Details of each technique with applications and status in various national wind tunnels are given.

Design of control laws for flutter suppression based on the aerodynamic energy concept and comparisons with other design methods

NASA Technical Reports Server (NTRS)

Nissim, E.

1989-01-01

The aerodynamic energy method is used in this paper to synthesize control laws for NASA's Drone for Aerodynamic and Structural Testing-Aerodynamic Research Wing 1 (DAST-ARW1) mathematical model. The performance of these control laws in terms of closed-loop flutter dynamic pressure, control surface activity, and robustness is compared against other control laws that appear in the literature and relate to the same model. A control law synthesis technique that makes use of the return difference singular values is developed in this paper. it is based on the aerodynamic energy approach and is shown to yield results superior to those given in the literature and based on optimal control theory. Nyquist plots are presented together with a short discussion regarding the relative merits of the minimum singular value as a measure of robustness, compared with the more traditional measure of robustness involving phase and gain margins.

Three-dimensional aerodynamic shape optimization of supersonic delta wings

NASA Technical Reports Server (NTRS)

Burgreen, Greg W.; Baysal, Oktay

1994-01-01

A recently developed three-dimensional aerodynamic shape optimization procedure AeSOP(sub 3D) is described. This procedure incorporates some of the most promising concepts from the area of computational aerodynamic analysis and design, specifically, discrete sensitivity analysis, a fully implicit 3D Computational Fluid Dynamics (CFD) methodology, and 3D Bezier-Bernstein surface parameterizations. The new procedure is demonstrated in the preliminary design of supersonic delta wings. Starting from a symmetric clipped delta wing geometry, a Mach 1.62 asymmetric delta wing and two Mach 1. 5 cranked delta wings were designed subject to various aerodynamic and geometric constraints.