Development and Application of a Low Cost Gas Dynamic Laser Test Facility.

摘要

This report describes the design, instrumentation and operation of two intermittent facilities for Gas Dynamic Laser research. Intermittent facilities have the attractive characteristics of very low cost, configuration flexibility, and ease of conducting tests with a large dynamic range of initial conditions. The kinetics of vibrational freezing in gas dynamic laser nozzles was studied. Small signal gain, static temperature, pressure and Mach number were measured downstream of the nozzle exit. Results for different mixtures, total temperatures, and area ratio changes are presented. Results of a research program to study the effects of contraction ratio, length, and wedge angle on the performance of a vane diffuser are presented. The effects of promoting early boundary layer transition are shown to be important in vane diffusers. A separate study was performed to determine the effects of impulsive starting vane diffusers compared with quasi-steady starting. The results conclusively show no change of start or unstart performance due to impulsive operation.