Wind Tunnel Tests of Hypersonic Inlets for Ramjet Modules of Ramjet-scramjet Combined Engine

The preliminary test study is conducted on hypersonic inlets for ramjet module of the ramjet-scramjet combined engine at a Mach number of 6 in a high enthalpy tunnel.The performance and static pressure distributions of the inlet under different back-pressure conditions are obtained.Results indicate:(1)The mass flow ratio of the inlet is greater than 0.98 at a Mach number of 6,at the throat section the total pressure recovery coefficient and the average Mach number are 0.52 and 2.68 respectively.When the back pressure increases to the critical value which is about 267.56 times of the free stream pressure,the total pressure coefficient reaches 0.171 and the average Mach number is lowered to 0.432 at the inlet's exit,which contributes greatly to the efficiency and stability of the ramjet combustion and the cooperation of the ramjet and scramjet.(2)When the mixing duct's exit is fully open,the static pressure fluctuates greatly along the top surface and bottom surface and the value of the former is always higher due to the curved duct.Different from ducts with constant cross section area,the average Mach number at the inlet's exit decreases monotonously and the total pressure recovery coefficient decreases to the minimum and then increases slowly until buzz occurs.In addition,when total pressure of the coming flow increases from 3.0 MPa to 5.5 MPa,there is no obvious change in either the flow pattern or the performance of the inlet.