Comparison Of Relative Costs Of Thermal Analysis Methods For Hypersonic Vehicle Compartments
In order to design the cooling systems of re-entry vehicles, judgment must b exercised in selecting the appropriate method for determining the transient heat transfer through complex structure into manned and equipment compartments. The accuracy must be consistent with the available calendar time, manpower and dollar cost in making this judgment. The heat flow can be determined analytically by several computing methods and experimentally by several laboratory testing methods.
This report presents the results of a study to examine the relationships between accuracy and cost in manhours, calendar time and dollars, in determining this transient heat flow for two hypothetical re-entry vehicles.
Accuracy and cost information were obtained for analytical methods: hand calculations, digital computers, differential analyzers, and passive element analogues; and for experimental methods: various size panels, half and full size vehicles, and vehicle compartments. Results are presented as curves of accuracy as a function of cost.
For the problems of this study, a general heat transfer digital computer program provides the most accuracy for the least cost. The other computing techniques rank in the following order: differential analyzer, passive element analogue, and hand calculations. The differential analyzer is the best method for parameter studies where a large number of runs is expected.
Experimental methods cannot compete with analytical methods in dollar cost, calendar time, or manhours. However, by obtaining material thermal properties experimentally, confidence can be increased in analytical solutions.
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