Experimental validation of a new type of direct-connect facility for scramjet studies

Abstract

Combustion chamber design has been important to the development of scramjet engines for a long time. Conventional experimental facilities of scramjet could be divided into two types: free-jet and direct-connect facilities. Free-jet facility can provide real incoming conditions to the combustion chamber, especially the real shock wave train structures formed in inlet and isolator. Unfortunately, it is relatively expensive. While direct-connect facility has a distinct advantage in experimental cost and period, so it has been used widely in relevant researches. However, traditional direct-connect facility usually can only provide a uniform incoming flow, which is much different from the distorted flow field in real scramjet, and this is a non-negligible disadvantage to relevant design. An inverse design method based on method of characteristics (MOC) is presented to solve this problem. The facility designed by this new method can produce the pre-assigned distorted flow field without encountering unstart phenomenon. In this paper, experimental investigation of the new direct-connect facility, which is designed to reproduce a specific distorted flow field with Mach number more than 2, is further presented. Test data of particle image velocimetry (PIV), flow visualization experiments and corresponding numerical simulation results are used to verify the reliability and accuracy of this new facility. Qualitative flow visualization and quantitative measurement results further prove that this new type of direct-connect facility can generate the target distorted flow field as pre-defined.