Search NASA⌕ Search

SEARCH · Search NASA

Results for “Experiment vehicle”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Nonequilibrium thermal radiation for an aeroassist flight experiment vehicle

The direct-simulation Monte Carlo method incorporating a dissociating and ionizing gas model for air with thermal radiation is used to characterize the hypersonic flow about an axisymmetric representation of an aeroassist flight experiment (AFE) vehicle, whose freestream conditions correspond to selected points along the entry, aerobraking, and exit phases of the trajectory. Calculations for two trajectory conditions indicate that the radiative heating of the AFE forebody is lower than the convective heating, but becomes significant as the maximum convective heating rate condition is approached.

Moss, James N.↗
NASA NTRS1986

Calculation of convective heating on proposed aeroassist flight experiment vehicle

Convective heating calculations of a NASA aeroassist flight experiment (AFE) configuration consisting of a blunted, elliptic cone raked off at the base, and fitted with a skirt-type afterbody with a generous corner radius, are presented. The HALIS inviscid flowfield code is used to supply edge properties to an approximate three-dimensional boundary-layer method to calculate the surface heating. Calculations at Mach number 9.86 and approximate Reynolds number of 500,000, for angles of attack from -10 to 10 degrees, are in general good agreement with Langley 31-inch Mach 10 Tunnel experimental data. The results validate the application of the present overall AFE configuration heating pattern heating contours to aeroassist orbital transfer vehicle heating distribution determinations.

Hamilton, H. H., II↗
NASA NTRS1981

Anatomy of an entry vehicle experiment

The anatomy and evolution of a simple small-scale unmanned entry vehicle is described that is delivered to orbit by the shuttle and entered into the atmosphere from orbit to acquire flight data to improve our knowledge of boundary-layer behavior and evaluate advanced thermal protection systems. The anatomy of the experiment includes the justification for the experiments, instrumentation, configuration, material, and operational needs, and the translation of these needs into a configuration, weight statement, aerodynamics, program cost, and trajectory. Candidates for new instrumentation development are also identified for nonintrusive measurements of the boundary-layer properties.

Eide, D. G.↗
NASA NTRS1990

The Importance of the Measurement of the Unsteady Wake of the Aeroassist Flight Experiment Vehicle: A White Paper

The High Frequency Radiometer (HFR) is the only instrument on the Aeroassist Flight Experiment (AFE) with sufficient temporal resolution to discern the frequency of unsteady wake oscillations. Determining both the frequency and amplitude of wake unsteadiness during AFE atmospheric entry is essential for reliably predicting the geometry and motion of the wake of future Aeroassisted Space Transfer Vehicles (ASTV). These parameters directly affect the location and size of the pay- load and the weight of the required afterbody heat protection. The purpose of the AFE is to validate the technologies required for the design of ASTVs, which will be used to exploit Earth-lunar space. This validation will be conducted at a combination of vehicle size, altitude, and velocity not obtainable in ground-based facilities. The AFE will provide the experimental flight data needed to improve our understanding of hypersonic-wake physics and to validate computational predictions of the aerodynamic and heating loads, including afterbody radiative heating loads, on an ASTV. Reliable prediction of ASTV wake flows will ensure that payloads are located within the shear-layer envelope and will determine the amount of thermal protection the payloads require. Specifically, understanding the temporal nature of the wake unsteadiness is important for two reasons. Most importantly, analysis of ground-based experiments suggests that wake unsteadiness results in a variation of as much as +/- 5 deg in the shear-flow turning angle. This angle must be reliably predicted to avoid shear-layer impingement on the vehicle afterbody, which would result in heating rates of about 10 W/sq cm, of the same order as on the forebody stagnation point. Secondly, the energy associated with wake unsteadiness will reduce the static enthalpy of the wake fluid and cause an error of as much as 30% in the amount of predicted wake radiative heating. Therefore, the HFR flight data, which will quantify the frequency and amplitude of the wake unsteadiness, are required for the verification of computational models of ASTV flowfields. Measurement of wake unsteadiness has been endorsed by the Peer Science Steering Group and the AFE Computational Fluid Dynamics (CFD) Working Group. The Peer Science Steering Group has stressed that a reliable measurement of the wake unsteadiness is fundamental because incorporating unsteadiness represents a substantial challenge to the CFD community, and a reliable measurement will raise confidence in the computer simulation. The AFE CFD Working Group has stated that 44 any data which would prove the existence and effects of unsteady flow would be extremely valuable.

Strawa, A. W.↗
NASA NTRS1989

Conservation equations and physical models for hypersonic air flows over the aeroassist flight experiment vehicle

The code development and application program for the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA), with emphasis directed toward support of the Aeroassist Flight Experiment (AFE) in the near term and Aeroassisted Space Transfer Vehicle (ASTV) design in the long term is reviewed. LAURA is an upwind-biased, point-implicit relaxation algorithm for obtaining the numerical solution to the governing equations for 3-D, viscous, hypersonic flows in chemical and thermal nonequilibrium. The algorithm is derived using a finite volume formulation in which the inviscid components of flux across cell walls are described with Roe's averaging and Harten's entropy fix with second-order corrections based on Yee's Symmetric Total Variation Diminishing scheme. Because of the point-implicit relaxation strategy, the algorithm remains stable at large Courant numbers without the necessity of solving large, block tri-diagonal systems. A single relaxation step depends only on information from nearest neighbors. Predictions for pressure distributions, surface heating, and aerodynamic coefficients compare well with experimental data for Mach 10 flow over an AFE wind tunnel model. Predictions for the hypersonic flow of air in chemical and thermal nonequilibrium over the full scale AFE configuration obtained on a multi-domain grid are discussed.

Gnoffo, Peter A.↗
NASA NTRS2015

Entry Descent and Landing Workshop Proceedings: Inflatable Reentry Vehicle Experiment-3 (IRVE-3) Project Overview & Instrumentation - Volume 1

Entry mass at Mars is limited by the payload size that can be carried by a rigid capsule that can fit inside the launch vehicle fairing. Landing altitude at Mars is limited by ballistic coefficient (mass per area) of entry body. Inflatable technologies allow payload to use full diameter of launch fairing, and deploy larger aeroshell before atmospheric interface, landing more payload at a higher altitude. Also useful for return of large payloads from Low Earth Orbit (LEO).

Dillman, Robert↗
DOE OSTI2020

Design and out-of-pile testing of a novel irradiation experiment vehicle to support qualification of nuclear thermal propulsion components

Fission power systems have demonstrated higher thermal energy density per unit mass than chemical systems. High mass specific energy density offers advantages in space thermal propulsion applications. In the 1960s, nuclear thermal propulsion (NTP) development included the ROVER/NERVA program, in which full-scale prototype reactors were tested on the ground using hydrogen as the reactor coolant and propellant. NTP systems are being revisited, with expectations of improved performance resulting from improved fuel materials, allowing propellant temperatures near 2,800 K and over 20 thermal propulsion cycles. An apparatus has been developed to test NTP fuel materials in a research reactor at temperature and in a radiation environment typical of the NTP application. Here, this paper presents the design constraints, preliminary scoping thermal analysis, and basic thermal qualification testing for the out-of-pile experiment set apparatus, or OUTSET.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1988

Numerical simulation of hypersonic flow over an aeroassist flight experiment vehicle

Solutions of wind-tunnel and entry-flight flow around the vehicle are obtained from the Navier-Stokes equations coupled with the chemical species continuity equations if needed. The time-iterative method employs several techniques: shock fitting, chemistry-split ADI and an algebraic grid in conformal spherical-polar space. Sensitivities of the results to numerical parameters and to frozen, equilibrium and finite rate reactions are investigated in the forebody computation. Quantitative results are obtained for the shock layer and the near wake for the entire vehicle corresponding to both ground test and flight conditions. Complex flow characteristics are analyzed on the basis of the complete flowfield over the aerobrake and simplified afterbodies. The method is stable and cost effective, and has yielded shock locations and wall pressure distributions which are in good agreement with wind-tunnel data.

Li, C. P.↗
NASA NTRS1987

Simulation of real-gas effects on pressure distributions for a proposed Aeroassist Flight Experiment vehicle and comparison to prediction

Pressure distributions measured on a 60-deg elliptic cone, raked off at a 73-deg angle and having an ellipsoid nose (ellipticity equal to 2.0), are presented for a range of angle of attack from -10 to 15 deg. The high normal shock density ratio aspect of a real gas was simulated by testing in Mach-6 air (normal shock density ratio equal to 5.25) and Mach 6 CF4 (normal shock density ratio equal to 12.0). The effects of Reynolds number, angle of attack, and normal shock density ratio on these measurements are examined, and comparisons are made to an inviscid flowfield computer code known as HALIS. A significant effect of density ratio on pressure distributions on the cone section of the configuration was observed; the magnitude of this effect decreased with increased angle of attack. The effect of Reynolds number on pressures was negligible for forebody pressure distributions, but a measurable effect was noted on base pressures. In general, the HALIS code accurately predicted the measured pressure distributions in air and CF4.

Micol, John R.↗
NASA NTRS1989

Aerodynamic stability and heating analyses for the aeroassist flight experiment vehicle

Since ground based flow simulations are presently unable to model flight conditions expected for AOTVs (Aeroassist Orbital Transfer Vehicle) and other hypersonic space vehicles, computer codes are being developed to provide design parameters necessary for structure, guidance, and control aspects. Over the past four years, VRFLO (Viscous Reactive Flow) has been written to model finite-rate chemistry and viscous effects for a variety of aerobrake bodies. VRFLO includes a number of unique features that are summarized as follows: (1) Grid generation is an integral part of the code for several aerobrake configurations which includes the wake flow region; (2) The formulation is valid for three air chemical models; (3) An ADI central difference technique is used to solve the Navier-Stokes and species continuity equations in split groups; and (4) Grid density and numerical damping are minimized by shock-fitting and conformal mapping of body points.

Mcgary, J.↗
NASA NTRS1992

Simulation of real-gas effects on pressure distributions for aeroassist flight experiment vehicle and comparison with prediction

Pressure distributions measured on a 60 degree half-angle elliptic cone, raked off at an angle of 73 degrees from the cone centerline and having an ellipsoid nose (ellipticity equal to 2.0 in the symmetry plane) are presented for angles of attack from -10 degrees to 10 degrees. The high normal shock density ratio aspect of a real gas was simulated by testing in Mach 6 air and CF sub 4 (density ratio equal to 5.25 and 12.0, respectively). The effects of Reynolds number, angle of attack, and normal shock density ratio on these measurements are examined, and comparisons with a three dimensional Euler code known as HALIS are made. A significant effect of density ratio on pressure distributions on the cone section of the configuration was observed; the magnitude of this effect decreased with increasing angle of attack. The effect of Reynolds number on pressure distributions was negligible for forebody pressure distributions, but a measurable effect was noted on base pressures. In general, the HALIS code accurately predicted the measured pressure distributions in air and CF sub 4.

Micol, John R.↗
NASA NTRS1992

A hypersonic shock tunnel test of the Aeroassist Flight Experiment (AFE) vehicle at high altitude test conditions

The Aeroassist Flight Experiment (AFE) vehicle is a 4.26 m-diameter raked and blunted elliptic cone that is intended to obtain aerodynamic and aerothermodynamic data on blunt bodies at velocities near 10 km/s and altitudes above 75 km. Previous wind tunnel tests of this configuration have been at Mach numbers of 10 or lower. The present test program consisted of five test conditions at Mach numbers between 15 and 20 and simulated altitudes from 75 km to 97 km. Static longitudinal aerodynamic coefficients, the lift-to-drag ratio, and the trim angle-of-attack were obtained for angles-of-attack between 7 deg and 27 deg. The effects of angle-of-attack and shock Reynolds number, Re2, have been studied. These results indicate the AFE configuration is longitudinally stable. The variation of normal force slope, CNalpha and lift-to-drag slope, (L/D)alpha as well as the trim angle-of-attack with Re2 are documented. The trim angle-of-attack increases with decreasing values of shock Reynolds number (increasing altitude) while the lift-to-drag ratio at the trimmed conditions is relatively constant.

Wittliff, C. E.↗