Abstract

The presentation presents two empirical methods to bridge the gap between computational fluid dynamics codes and physical optics codes. The two empirical methods that define the turbulence fluctuations and scale sizes are compared to available test data. The complete solution to several stressing Endo Leap design points are presented. The results for both external window film cooling and internal cooling are combined with the thermal gradients in the window to predict the total optical distortion. The method of obtaining optical path differences within the window is applicable to either external or internal cooling. The results of the analyses indicate that an internally cooled window has potentially no aero-optic image degradation. External film cooling causes varying amounts of image degradation, depending on the type of cooling and the flow conditions. These results agree with test data and empirical calculations. The computational fluid dynamics and physical optics codes have been in use for years and are well verified.

© 1992 Optical Society of America