NOL Hypersonic Tunnel No. 4 Results 2: Diffuser Investigation
NAVAL ORDNANCE LAB WHITE OAK MD
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Results of a diffuser investigation in the continuous 12 x 12 cm on Hypersonic Tunnel No. 4 are presented. A brief introduction describes previous supersonic diffuser work. The diffuser investigated and the experimental techniques are then discussed. The results show first that air condensation has little or no effect on diffuser performance. Data on diffuser throat areas and overall pressure ratios needed to start and maintain hypersonic flow are given for a Mach number range from 5.9 to 9.6. The effect of two different throat locations and different diffuser configurations on tunnel performance is investigated. A peaked throat diffuser with 3 deg wall divergence aft of the throat was selected for a more detailed study. The pressure recovered by this optimum diffuser in the range 5.9 or M or 9.6 varies from 1.8 to 2.3 times the value of the pressure recovered by a pitot tube operated at equal Mach number. The best performance with 2.3 times pitot recovery is achieved at M 7. 2 Spark schlieren photographs taken throughout the test section and diffuser show the shock waves and boundary layers. Also tunnel starting requirements were measured and are discussed.
- Test Facilities, Equipment and Methods
- Fluid Mechanics