NOL Hyperballistics Tunnel No. 4, Results. 5. Experimental and Theoretical Investigation of a Cooled Hypersonic Wedge Nozzle
NAVAL ORDNANCE LAB WHITE OAK MD
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A new water-cooled, wedge-type nozzle has been in operation in the NOL 12- x 12-cm Hypersonic Tunnel No. 4 since January 1952. This report presents results of theoretical and experimental investigations covering the performance of this nozzle. It was found from measurements of pitot and static pressure that the nozzle produced a shock-free, almost isentropic expansion having a test-section Mach number distribution comparable in quality to that obtained in existing conventional nozzles at lower Mach numbers. The cooling system used was adequate to maintain the nozzle block temperatures at constant low values. The temperature distribution in a nozzle block was also measured, and it showed a rise near the throat. This rise agreed qualitatively with theoretical calculations. A comparison of the calculated and measured rate of heat transfer to a nozzle block suggested that boundary-layer transition occurs after the throat. A pressure and temperature survey at the end of a nozzle block where the boundary layer is turbulent showed that the velocity distribution is similar to that found at low speed. This survey was also used to calculate the over-all heat transfer rate to the nozzle block. This result agreed with that obtained from the direct method of determining the heat transfer by measuring the cooling water rate and temperature increase. In conclusion it is found that a hypersonic wedge nozzle produces shock free expansions and acceptable flow in the test section and serves well as a research tool.
- Fluid Mechanics
- Test Facilities, Equipment and Methods