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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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10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Description of an aeronautical geometry conversion package: Wave-drag to Langley Wireframe Geometry Standard (LaWGS) to Supersonic Implicit Marching Potential (SIMP)

Documented is an aeronautical geometry conversion package which translates wave-drag geometry into the Langley Wireframe Geometry Standard (LaWGS) format and then into a format which is used by the Supersonic Implicit Marching Potential (SIMP) program. The programs described were developed by Computer Sciences Corporation for the Advanced Vehicles Division/Advanced Concepts Branch at NASA Langley Research Center. Included also are the input and output from a benchmark test case.

Wiese, Michael R.↗
NASA NTRS2011

Plasma Sheet Velocity Measurement Techniques for the Pulsed Plasma Thruster SIMP-LEX

The velocity of the first plasma sheet was determined between the electrodes of a pulsed plasma thruster using three measurement techniques: time of flight probe, high speed camera and magnetic field probe. Further, for time of flight probe and magnetic field probe, it was possible to determine the velocity distribution along the electrodes, as the plasma sheet is accelerated. The results from all three techniques are shown, and are compared for one thruster geometry.

Nawaz, Anuscheh↗
NASA NTRS1987

Supersonic flow computations over aerospace configurations using an Euler marching solver

For fully supersonic flows, an efficient strategy for obtaining numerical solutions is to employ space marching techniques. A full potential marching technique, known as the SIMP code and capable of handling such embedded subsonic regions, has achieved some success analyzing low supersonic Mach number flows. The extension of the full potential approach to the Euler equation which model the exact nonlinear inviscid gas dynamic flow processes is presented. Within the assumption of an inviscid flow, such an Euler marching solver can be applied to a wide class of shocked flows including the hypersonic range. The intent is to maintain some of the basic features of the full potential SIMP code within the Euler solver in dealing with geometry input, gridding techniques, and input/output routines including post processing of results. An Euler marching code known as EMTAC was developed. Results obtained for a variety of configurations involving canard, wing, horizontal tail, flow-through inlet, and fuselage using both the EMTAC and SIMP codes are reported. For shocked cases satisfying the isentropic assumption, the EMTAC and SIMP codes produced practically the same results. In terms of execution time, the EMTAC code is slower.

Szema, Kuo-Yen↗
NASA NTRS1986

Nonlinear Supersonic Full Potential Analysis

Supersonic Implicit Marching Program (SIMP) applies numerical method, based on conservative form of full potential equation, to problem of threedimensional supersonic flows with embedded subsonic regions. Conservative formulation of problem provides ability to capture shocks and to assess accurately impact of sweep, thickness, and lift for conditions where linear theory unsatisfactory. Technique uses characteristic signal-propagation theory to control density biasing for treatment of shocks (including embedded shocks) and mixed elliptic/hyperbolic crossflow. SIMP written in FORTRAN 77.

Shankar, V.↗
NASA NTRS1996

Software Aids Visualization Of Mars Pathfinder Mission

Report describes Simulator for Imager for Mars Pathfinder (SIMP) computer program. SIMP generates "virtual reality" display of view through video camera on Mars lander spacecraft of Mars Pathfinder mission, along with display of pertinent textual and graphical data, for use by scientific investigators in planning sequences of activities for mission.

Weidner, Richard J.↗
NASA NTRS1992

Supersonic full-potential methods for missile body analysis

Accounts are presented of representative applications to missile bodies of arbitrary shape of methods based on the steady form of the full potential equation. The NCOREL and SIMP full-potential codes are compared, and their results are evaluated for the cases of an arrow wing and a wing-body configuration. Attention is given to the effect of cross-sectional and longitudinal geometries. Comparisons of surface pressure and longitudinal force and moment data for circular and elliptic bodies have shown that the full-potential methods yielded excellent results in attached-flow conditions. Results are presented for a conical star body, waveriders, the Shuttle Orbiter, and a highly swept wing-body cruising at Mach 4.

Pittman, James L.↗
NASA NTRS2002

IRAS Low Resolution Spectra of Asteroids

Optical/near-infrared studies of asteroids are based on reflected sunlight and surface albedo variations create broad spectral features, suggestive of families of materials. There is a significant literature on these features, but there is very little work in the thermal infrared that directly probes the materials emitting on the surfaces of asteroids. We have searched for and extracted 534 thermal spectra of 245 asteroids from the original Dutch (Groningen) archive of spectra observed by the IRAS Low Resolution Spectrometer (LRS). We find that, in general, the observed shapes of the spectral continua are inconsistent with that predicted by the standard thermal model used by IRAS. Thermal models such as proposed by Harris (1998) and Harris et al.(1998) for the near-earth asteroids with the "beaming parameter" in the range of 1.0 to 1.2 best represent the observed spectral shapes. This implies that the IRAS Minor Planet Survey (IMPS, Tedesco, 1992) and the Supplementary IMPS (SIMPS, Tedesco, et al., 2002) derived asteroid diameters are systematically underestimated, and the albedos are overestimated. We have tentatively identified several spectral features that appear to be diagnostic of at least families of materials. The variation of spectral features with taxonomic class hints that thermal infrared spectra can be a valuable tool for taxonomic classification of asteroids.

Cohen, Martin↗
NASA NTRSDate not supplied

Design of a Wind Tunnel Balance using Topology Optimization Considering Multifunctional Stress Performance

This paper proposes a new topology optimization formulation for multi-functional performance of a compliant sensor structure–a wind tunnel balance. Compliant mechanism design is one of the main applications of topology optimization and plenty of successful design studies have been reported. However, design practicability is still questionable when stress concentration is critical due to complex/combined loads, especially at compliant hinge joints. In this paper, we formulate a new topology optimization formulation considering multiple loading scenarios in a compliant sensor structure design. Two separate constraints,one related to sensor performance and the other focused on structural safety in terms of maximum von Mises stress, are included in the design formulation. This formulation is to achieve excellent sensitivity of an applied axial load while maintaining structure safety with a combined general load applied which is one order higher than the axial load. This challenging problem is solved using a well-known SIMP approach with the relaxation and projection methods.

Myung Kyun Sung↗