Engineering topics
Publications and source records attributed to Wagner, Howard A..
This slide presentation reviews the effort of code EA at Johnson Space Center (JSC) to identify and acquire databases and documents from the space shuttle program that are adjudged important for retention after the retirement of the space shuttle.
In order to conduct a thermal analysis of heat transfer to liquid hydrogen near the critical point, an accurate understanding of the thermal transport properties is required. A review of the available literature on hydrogen transport properties identified a lack of useful equations to predict the thermal conductivity and viscosity of liquid hydrogen. The tables published by the National Bureau of Standards were used to perform a series of curve fits to generate the needed correlation equations. These equations give the thermal conductivity and viscosity of hydrogen below 100 K. They agree with the published NBS tables, with less than a 1.5 percent error for temperatures below 100 K and pressures from the triple point to 1000 KPa. These equations also capture the divergence in the thermal conductivity at the critical point
Scalloping reflector surface reduces sensitivity to manufacturing and aiming errors. Contrary to intuition, most effective shape of concentrating reflector for solar heat engine is not perfect paraboloid. According to design studies for Space Station solar concentrator, scalloped, nonimaging approximation to perfect paraboloid offers better overall performance in view of finite apparent size of Sun, imperfections of real equipment, and cost of accommodating these complexities. Scalloped-reflector concept also applied to improve performance while reducing cost of manufacturing and operation of terrestrial solar concentrator.