Investigation of the Performance of a Variable Area Diffuser for Gas Dynamic Lasers.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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An experimental study was performed to determine the performance of a variable area diffuser downstrem of an array of supersonic nozzles, and to determine the Mach number profile between the nozzle exit and the diffuser entrance. The study was conducted on a blowdown wind tunnel and the test section was designed to model a gas dynamic laser with an array of five nozzle blades, a constant area section, and a converging-diverging diffuser. Air at a temperature of 70 degrees F and at total pressures ranging from 100 to 210 psig was expanded through an area ratio of approximately 66. Using various pressure measurements the Mach number was found to decrease from M 6.4 at the nozzle exit to approximately M 4.0 at the diffuser entrance. The rapid decrease was attributed to the irreversible effects of friction, the nozzle blade wakes, and the nozzle throat shocks. The minimum starting area ratio of the diffuser was 0.59, which agrees well with one dimensional theory.
- Lasers and Masers