Experimental investigation of Mach 6 optimal hypersonic nozzle performance in shock tunnel

The performance of a Mach 6 Hypersonic nozzle designed to be installed in a reflective shock tunnel has been experimentally investigated in this paper. The purpose of nozzle performance is to create a uniform flow at the outlet and a suitable test time considering the starting flow inside the nozzle. This nozzle is designed using modern optimization methods based on a classic converging-diverging nozzle. Also, the design and construction of a total pressure rake is presented to evaluate the flow quality in the test section. The complexity of investigating hypersonic flows is the sensitivity of the flow to the existence of various types of disturbances and also fluctuations caused by acoustic waves. Therefore, in hypersonic flow, considerations related to the design of the test section as well as the geometry of the pressure rake are very important. In this paper, the dynamics of the reflected shock wave in the shock tube and the starting waves in the test section are investigated. The pressure upstream of the nozzle is in good agreement with the design values with an error of 4%. The Mach number distribution is presented by measuring the pressure distribution at the end of the nozzle. Finally, the Mach number distribution at the nozzle outlet has been compared with the numerical results which shows an error about 3%. The uniformity of the flow at the end of the nozzle, which has been observed numerically and experimentally, shows the effectiveness of the optimal design method of the ultrasonic nozzle.