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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Experiments on the ground vortex formed by an impinging jet in cross flow

An inclined jet impinging on the ground creates a wall flow that spreads radially from the point of impingement. If a cross-flow is introduced, the upstream component of the wall flow will separate from the ground and create what has been termed the 'ground vortex.' The ground vortex has been shown to have a significant impact on aircraft aerodynamics and is one of the major contributors to hot gas ingestion. The paper discusses a recent study which included a generic wing-body configuration for assessing the impact of the ground vortex on configuration aerodynamics. Wind tunnel tests using fixed ground boards, moving ground belts, and moving model tests are discussed. The emphasis of the data is macroscopic, i.e. forward location of the vortex, effects of ground height, etc.

Blake, William B.↗
NASA NTRS2005

Introduction of the ASP3D Computer Program for Unsteady Aerodynamic and Aeroelastic Analyses

A new computer program has been developed called ASP3D (Advanced Small Perturbation 3D), which solves the small perturbation potential flow equation in an advanced form including mass-consistent surface and trailing wake boundary conditions, and entropy, vorticity, and viscous effects. The purpose of the program is for unsteady aerodynamic and aeroelastic analyses, especially in the nonlinear transonic flight regime. The program exploits the simplicity of stationary Cartesian meshes with the movement or deformation of the configuration under consideration incorporated into the solution algorithm through a planar surface boundary condition. The new ASP3D code is the result of a decade of developmental work on improvements to the small perturbation formulation, performed while the author was employed as a Senior Research Scientist in the Configuration Aerodynamics Branch at the NASA Langley Research Center. The ASP3D code is a significant improvement to the state-of-the-art for transonic aeroelastic analyses over the CAP-TSD code (Computational Aeroelasticity Program Transonic Small Disturbance), which was developed principally by the author in the mid-1980s. The author is in a unique position as the developer of both computer programs to compare, contrast, and ultimately make conclusions regarding the underlying formulations and utility of each code. The paper describes the salient features of the ASP3D code including the rationale for improvements in comparison with CAP-TSD. Numerous results are presented to demonstrate the ASP3D capability. The general conclusion is that the new ASP3D capability is superior to the older CAP-TSD code because of the myriad improvements developed and incorporated.

Batina, John T.↗
NASA NTRS1996

Simulations of Active Vortex Generators

We are interested in the study, via numerical simulations, of active vortex generators. Vortex generators may be used to modify the inner part of the boundary layer or to control separation thus enhancing the performance and maneuverability of aerodynamic configurations. We consider generators that consist of a surface cavity elongated in the streamwise direction and partially covered with a moving lid that at rest lies flush with the boundary. Streamwise voracity is generated and ejected due to the oscillatory motion of the lid. The present simulations c Implement relevant experimental investigations of active vortex generators that have been conducted at NASA Ames Research Center and Stanford University. Jacobson and Reynolds used a piezoelectric device in water, allowing for small amplitude high frequency oscillations. They placed the lid asymmetrically on the cavity and observed a strong outward velocity at the small gap of the cavity. Saddoughi used a larger mechanically driven device in air to investigate this flow and observed a jet emerging from the wide gap of the configuration, contrary to the findings of Jacobson and Reynolds. More recently, Lachowiez and Wlezien are investigating the flow generated by an electro-mechanically driven lid to be used for assertion control in aerodynamic applications. We are simulating the flows generated by these devices and we are conducting a parametric study that would help us elucidate the physical mechanisms present in the flow. Conventional computational schemes encounter difficulties when simulating flows around complex configurations undergoing arbitrary motions. Here we present a formulation that achieves this task on a purely Lagrangian frame by extending the formulation presented by Koumoutsakos, Leonard and Pepin. The viscous effects are taken into account by modifying the strength of the particles, whereas fast multipole schemes employing hundreds of thousands ol'particle's allow for high resolution simulations. We shall present simulation results of an oscillating plate at various Reynolds numbers and Strouhal frequencies. Estimates of the forces needed to drive the devices will also be presented.

Mansour, N. N.↗
NASA NTRS1995

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

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

Phillips, W. P.↗
NASA NTRS2000

Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program

The NASA Langley Configuration Aerodynamics Branch has conducted an experimental investigation to study the static performance of innovative thrust reverser concepts applicable to high-bypass-ratio turbofan engines. Testing was conducted on a conventional separate-flow exhaust system configuration, a conventional cascade thrust reverser configuration, and six innovative thrust reverser configurations. The innovative thrust reverser configurations consisted of a cascade thrust reverser with porous fan-duct blocker, a blockerless thrust reverser, two core-mounted target thrust reversers, a multi-door crocodile thrust reverser, and a wing-mounted thrust reverser. Each of the innovative thrust reverser concepts offer potential weight savings and/or design simplifications over a conventional cascade thrust reverser design. Testing was conducted in the Jet-Exit Test Facility at NASA Langley Research Center using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0. All tests were conducted with no external flow and cold, high-pressure air was used to simulate core and fan exhaust flows. Results show that the innovative thrust reverser concepts achieved thrust reverser performance levels which, when taking into account the potential for system simplification and reduced weight, may make them competitive with, or potentially more cost effective than current state-of-the-art thrust reverser systems.

Asbury, Scott C.↗
NASA NTRS2000

Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program

The NASA Langley Configuration Aerodynamics Branch has conducted an experimental investigation to study the static performance of innovative thrust reverser concepts applicable to high-bypass-ratio turbofan engines. Testing was conducted on a conventional separate-flow exhaust system configuration, a conventional cascade thrust reverser configuration, and six innovative thrust reverser configurations. The innovative thrust reverser configurations consisted of a cascade thrust reverser with porous fan-duct blocker, a blockerless thrust reverser, two core-mounted target thrust reversers, a multi-door crocodile thrust reverser, and a wing-mounted thrust reverser. Each of the innovative thrust reverser concepts offer potential weight savings and/or design simplifications over a conventional cascade thrust reverser design. Testing was conducted in the Jet-Exit Test Facility at NASA Langley Research Center using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0. All tests were conducted with no external flow and cold, high-pressure air was used to simulate core and fan exhaust flows. Results show that the innovative thrust reverser concepts achieved thrust reverser performance levels which, when taking into account the potential for system simplification and reduced weight, may make them competitive with, or potentially more cost effective than current state-of-the-art thrust reverser systems. All data gathered in this investigation are contained in the CD-ROM.

Asbury, Scott C.↗
NASA NTRS1988

Knowledge-based zonal grid generation for computational fluid dynamics

Automation of flow field zoning in two dimensions is an important step towards reducing the difficulty of three-dimensional grid generation in computational fluid dynamics. Using a knowledge-based approach makes sense, but problems arise which are caused by aspects of zoning involving perception, lack of expert consensus, and design processes. These obstacles are overcome by means of a simple shape and configuration language, a tunable zoning archetype, and a method of assembling plans from selected, predefined subplans. A demonstration system for knowledge-based two-dimensional flow field zoning has been successfully implemented and tested on representative aerodynamic configurations. The results show that this approach can produce flow field zonings that are acceptable to experts with differing evaluation criteria.

Andrews, Alison E.↗
NASA NTRS1975

An investigation in the NASA MSFC 14-inch trisonic wind tunnel to determine the pressure distribution over the components of a 0.004 scale version of the Rockwell MCR 0074 baseline shuttle ascent configuration (IA32F), volume 1

Data were obtained for Mach numbers from 0.6 to 3.48, angles of attack from -10 to 10 degrees, and angles of sideslip from -10 to 10 degrees at zero angle of attack. Also, -4 and 4 degrees sideslip were run for an angle of attack of -5 and 5 degrees. Aerodynamic configurations of the solid rocket motors, external tank, and orbiter are shown. Graphs of plotted pressure data (pressure coefficients) for the external tank and solid rocket motors are given. A description of the test facility is included.

Ramsey, P. E.↗
NASA NTRSDate not supplied

CDISC Remote Design Method to Simulate Aircraft Interference Effects for the CATNLF Flight Test

The Crossflow Attenuated Natural Laminar Flow (CATNLF)flight test is an experimental evaluation of a laminar flow design approach that will be conducted on a small transonic wing-like model suspended from the Centerline Instrumented Pylon (CLIP) underneath an F-15 vehicle. The upcoming flight testis anticipated to provide experimental data that may be useful for transition prediction code calibrations or laminar flow computational studies. For the computational results to be reliable, relevant aerodynamics must be included in the simulations. It has been shown that the F-15 vehicle produces a notable aerodynamic influence on the CATNLF test article, and that removing the F-15 vehicle from the simulation significantly alters the laminar flow behavior. Because the F-15 vehicle is not a publicly-releasable geometry, if the CATNLF flight test dataset is to be widely used by the community, an alternative method to ensure that the CATNLF test article flight configuration aerodynamics is properly modeled is required. The objective of this research is to use the CDISC aerodynamic design tool to perform a remote design of a surface that would replicate the aerodynamic influence on the CATNLF test article. This new design approach, referred to as the Equivalent Loading via Interference Surface Effects (ELISE), is presented in this paper, including the details on the design setup and results. The ELISE design successfully reproduced theF-15 influence on the CATNLF test article, with predicted transition location within an average of 4% chord of the full flight configuration. An off-design assessment is included for small perturbations in Mach and sideslip angle that suggest the ELISE design can cover a reasonable range of expected flight conditions with the same geometry. This paper is intended to explain the design approach, as well as show results that can be expected when utilizing the ELISE design method.

CDISC↗
NASA NTRSDate not supplied

CDISC Remote Design Method to Simulate Aircraft Interference Effects for the CATNLF Flight Test

The Crossflow Attenuated Natural Laminar Flow (CATNLF) flight test is an experimental evaluation of a laminar flow design approach that will be conducted on a small transonic wing-like model suspended from the Centerline Instrumented Pylon (CLIP) underneath an F-15 vehicle. The upcoming flight test is anticipated to provide experimental data that may be useful for transition prediction code calibrations or laminar flow computational studies. For the computational results to be reliable, relevant aerodynamics must be included in the simulations. It has been shown that the F-15 vehicle produces a notable aerodynamic influence on the CATNLF test article, and that removing the F-15 vehicle from the simulation significantly alters the laminar flow behavior. Because the F-15 vehicle is not a publicly-releasable geometry, if the CATNLF flight test dataset is to be widely used by the community, an alternative method to ensure that the CATNLF test article flight configuration aerodynamics is properly modeled is required. The objective of this research is to use the CDISC aerodynamic design tool to perform a remote design of a surface that would replicate the aerodynamic influence on the CATNLF test article. This new design approach, referred to as the Equivalent Loading via Interference Surface Effects (ELISE), is presented in this paper, including the details on the design setup and results. The ELISE design successfully reproduced the F-15 influence on the CATNLF test article, with predicted transition location within an average of 4% chord of the full flight configuration. An off-design assessment is included for small perturbations in Mach and sideslip angle that suggest the ELISE design can cover a reasonable range of expected flight conditions with the same geometry. This paper is intended to explain the design approach, as well as show results that can be expected when utilizing the ELISE design method.

CDISC↗
NASA NTRS1981

High Reynolds number research - 1980

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

Mckinney, L. W.↗
NASA NTRS1984

Shock capturing finite difference algorithms for supersonic flow past fighter and missile type configurations

The construction of a reliable, shock capturing finite difference method to solve the Euler equations for inviscid, supersonic flow past fighter and missile type configurations is highly desirable. The numerical method must have a firm theoretical foundation and must be robust and efficient. It should be able to treat subsonic pockets in a predominantly supersonic flow. The method must also be easily applicable to the complex topologies of the aerodynamic configuration under consideration. The ongoing approach to this task is described and for steady supersonic flows is presented. This scheme is the basic numerical method. Results of work obtained during previous years are presented.

Osher, S.↗
NASA NTRS1998

Shuttle Liquid Fly Back Booster Configuration Options

This paper surveys the basic configuration options available to a Liquid Fly Back Booster (LFBB), integrated with the Space Shuttle system. The background of the development of the LFBB concept is given. The influence of the main booster engine (BME) installations and the Fly Back Engine (FBE) installation on the aerodynamic configurations are also discussed. Limits on the LFBB configuration design space imposed by the existing Shuttle flight and ground elements are also described. The objective of the paper is to put the constrains and design space for an LFBB in perspective. The object of the work is to define LFBB configurations that significantly improve safety, operability, reliability and performance of the Shuttle system and dramatically lower operations costs.

Healy, T. J., Jr.↗
NASA NTRS1998

Shuttle Liquid Fly Back Booster Configuration Options

This paper surveys the basic configuration options available to a Liquid Fly Back Booster (LFBB), integrated with the Space Shuttle system. The background of the development of the LFBB concept is given. The influence of the main booster engine (BME) installations and the fly back engine (FBE) installation on the aerodynamic configurations are also discussed. Limits on the LFBB configuration design space imposed by the existing Shuttle flight and ground elements are also described. The objective of the paper is to put the constrains and design space for an LFBB in perspective. The object of the work is to define LFBB configurations that significantly improve safety, operability, reliability and performance of the Shuttle system and dramatically lower operations costs.

Healy, Thomas J., Jr.↗