Starting characteristics of the hypersonic wind tunnel with the mach number variation

Abstract

The scramjet engine test facility (SETF) of the Korea Aerospace Research Institute is a blow-down, high enthalpy wind tunnel with a free-jet test cell. The free-jet test sections can reduce choking and test larger models compared with solid wall test sections, but the facility needs an excessive starting pressure ratio and is highly unpredictable because of the free-jet space. An air ejector system was designed to simulate a Mach 3.5 test condition. Quasi one-dimensional and computational analyses of the ejector were performed. The test results of the ejector well agree with the analysis results. The SETF showed a normal-shock efficiency of 58% at the Mach 3.5 condition. The air ejector system was modified to conduct a scramjet intake test with a Mach 6.7 condition. The normal-shock efficiency of the SETF was 40% with the Mach 6.7 condition. There was almost no change in the starting pressure ratio due to blockage.