Engineering topics

Amundsen, Ruth M.

Publications and source records attributed to Amundsen, Ruth M..

26 records · Page 2

NASA NTRS2000

Thermal Analysis Methods for an Earth Entry Vehicle

Thermal analysis of a vehicle designed to return samples from another planet, such as the Earth Entry vehicle for the Mars Sample Return mission, presents several unique challenges. The Earth Entry Vehicle (EEV) must contain Martian material samples after they have been collected and protect them from the high heating rates of entry into the Earth's atmosphere. This requirement necessitates inclusion of detailed thermal analysis early in the design of the vehicle. This paper will describe the challenges and solutions for a preliminary thermal analysis of an Earth Entry Vehicle. The aeroheatina on the vehicle during entry would be the main driver for the thermal behavior. and is a complex function of time, spatial position on the vehicle, vehicle temperature, and trajectory parameters. Thus. the thermal analysis must be closely tied to the aeroheating analysis in order to make accurate predictions. Also, the thermal analysis must account for the material response of the ablative thermal protection system TPS. For the exo-atmospheric portion of the mission, the thermal analysis must include the orbital radiation fluxes on the surfaces. The thermal behavior must also be used to predict the structural response of the vehicle (the thermal stress and strains) and whether they remain within the capability of the materials. Thus, the thermal analysis requires ties to the three-dimensional geometry, the aeroheating analysis, the material response analysis, the orbital analysis. and the structural analysis. The goal of this paper is to describe to what degree that has been achieved.

Amundsen, Ruth M.↗

NASA NTRS2000

Thermal Analysis Methods For Earth Entry Vehicle

Thermal analysis of a vehicle designed to return samples from another planet, such as the Earth Entry vehicle for the Mars Sample Return mission, presents several unique challenges. The Earth Entry Vehicle (EEV) must contain Martian material samples after they have been collected and protect them from the high heating rates of entry into the Earth's atmosphere. This requirement necessitates inclusion of detailed thermal analysis early in the design of the vehicle. This paper will describe the challenges and solutions for a preliminary thermal analysis of an Earth Entry Vehicle. The aeroheating on the vehicle during entry would be the main driver for the thermal behavior, and is a complex function of time, spatial position on the vehicle, vehicle temperature, and trajectory parameters. Thus, the thermal analysis must be closely tied to the aeroheating analysis in order to make accurate predictions. Also, the thermal analysis must account for the material response of the ablative thermal protection system (TPS). For the exo-atmospheric portion of the mission, the thermal analysis must include the orbital radiation fluxes on the surfaces. The thermal behavior must also be used to predict the structural response of the vehicle (the thermal stress and strains) and whether they remain within the capability of the materials. Thus, the thermal analysis requires ties to the three-dimensional geometry, the aeroheating analysis, the material response analysis, the orbital analysis, and the structural analysis. The goal of this paper is to describe to what degree that has been achieved.

Amundsen, Ruth M.↗

NASA NTRS1999

Comparison of Integrated Analysis Methods for Two Model Scenarios

Integrated analysis methods have the potential to substantially decrease the time required for analysis modeling. Integration with computer aided design (CAD) software can also allow a model to be more accurate by facilitating import of exact design geometry. However, the integrated method utilized must sometimes be tailored to the specific modeling situation, in order to make the process most efficient. Two cases are presented here that illustrate different processes used for thermal analysis on two different models. These examples are used to illustrate how the requirements, available input, expected output, and tools available all affect the process selected by the analyst for the most efficient and effective analysis.

Amundsen, Ruth M.↗

NASA NTRS1998

Hydrostar Thermal and Structural Deformation Analyses of Antenna Array Concept

The proposed Hydrostar mission used a large orbiting antenna array to demonstrate synthetic aperture technology in space while obtaining global soil moisture data. In order to produce accurate data, the array was required to remain as close as possible to its perfectly aligned placement while undergoing the mechanical and thermal stresses induced by orbital changes. Thermal and structural analyses for a design concept of this antenna array were performed. The thermal analysis included orbital radiation calculations, as well as parametric studies of orbit altitude, material properties and coating types. The thermal results included predicted thermal distributions over the array for several cases. The structural analysis provided thermally-driven deflections based on these cases, as well as based on a 1-g inertial load. In order to minimize the deflections of the array in orbit, the use of XN70, a carbon-reinforced polycyanate composite, was recommended.

Amundsen, Ruth M.↗

NASA NTRS1993

Some useful innovations with TRASYS and SINDA-85

Several innovative methods were used to allow more efficient and accurate thermal analysis using SINDA-85 and TRASYS, including model integration and reduction, planetary surface calculations, and model animation. Integration with other modeling and analysis codes allows an analyst to import a geometry from a solid modeling or computer-aided design (CAD) software package, rather than building the geometry 'by hand.' This is more efficient as well as potentially more accurate. However, the use of solid modeling software often generates large analytical models. The problem of reducing large models was elegantly solved using the response of the transient derivative to a forcing step function. The thermal analysis of a lunar rover implemented two unusual features of the TRASYS/SINDA system. A little-known TRASYS routine SURFP calculates the solar heating of a rover on the lunar surface for several different rover positions and orientations. This is used not only to determine the rover temperatures, but also to automatically determine the power generated by the solar arrays. The animation of transient thermal results is an effective tool, especially in a vivid case such as the 14-day progress of the sun over the lunar rover. An animated color map on the solid model displays the progression of temperatures.

Amundsen, Ruth M.↗

NASA NTRS1993

Integration of Design, Thermal, Structural, and Optical Analysis, Including Thermal Animation

In many industries there has recently been a concerted movement toward 'quality management' and the issue of how to accomplish work more efficiently. Part of this effort is focused on concurrent engineering; the idea of integrating the design and analysis processes so that they are not separate, sequential processes (often involving design rework due to analytical findings) but instead form an integrated system with smooth transfers of information. Presented herein are several specific examples of concurrent engineering methods being carried out at Langley Research Center (LaRC): integration of thermal, structural and optical analyses to predict changes in optical performance based on thermal and structural effects; integration of the CAD design process with thermal and structural analyses; and integration of analysis and presentation by animating the thermal response of a system as an active color map -- a highly effective visual indication of heat flow.

Amundsen, Ruth M.↗

NASA NTRS1993

Some Useful Innovations with Trasys and Sinda-85

Several innovative methods have been used to allow more efficient and accurate thermal analysis using SINDA-85 and TRASYS, including model integration and reduction, planetary surface calculations, and model animation. Integration with other modeling and analysis codes allows an analyst to import a geometry from a solid modeling or computer-aided design (CAD) software package, rather than building the geometry "by hand." This is more efficient as well as potentially more accurate. However, the use of solid modeling software often generates large analytical models. The problem of reducing large models has been elegantly solved using the response of the transient derivative to a forcing step function. The thermal analysis of a lunar rover implemented two unusual features of the TRASYS/SINDA system. A little-known TRASYS routine SURFP calculates the solar heating of a rover on the lunar surface for several different rover positions and orientations. This is used not only to determine the rover temperatures, but also to automatically determine the power generated by the solar arrays. The animation of transient thermal results is an effective tool, especially in a vivid case such as the 14-day progress of the sun over the lunar rover. An animated color map on the solid model displays the progression of temperatures.

Amundsen, Ruth M.↗

NASA NTRS1991

Thermal design and test results for SUNLITE ultra-stable reference cavity

SUNLITE (Stanford University-NASA Laser In-Space Technology Experiment) is a space-based experiment which uses a reference cavity to provide a stable frequency reference for a terahertz laser oscillator. Thermal stability of the cavity is a key factor in attaining a stable narrow-linewidth laser beam. The mount which is used to support and align the cavity will provide thermal isolation from the environment. The baseline requirement for thermal stability of the cavity is 0.025 C/min, but the design is directed toward achieving stability well beyond this requirement to improve the science data gained. A prototype of the cavity mount was fabricated and tested to characterize the thermal performance. The thermal vacuum test involved stable high-resolution temperature measurements and stable baseplate temperature control over long durations. Based on test data, the cavity mount design satisfies the severe requirement for the cavity thermal stability.

Amundsen, Ruth M.↗