Mach 8 Testing of a Scramjet Engine with Ramp Compression

To improve combustion efficiency and the inlet started condition, a scramjet model having a ramp combined with a single strut was tested under Mach 8 flight conditions at the Ramjet Engine Test Facility of the National Aerospace Laboratory, Japan. The attached ramp shielded some of the fuel injectors. The fuel flow rate from the open injectors to the flow path was designated as the effective fuel flow rate. In the tests, a combustion efficiency of 90% was attained with vertical injection of hydrogen fuel. The thrust increase was 590 N at the effective equivalence ratio of 1.3. However, because the engine geometry was not optimized, a sufficient increase of the thrust was not attained. High temperature and high pressure necessary for ignition and combustion were achieved by the ramp. When the pressure in the isolator was 160 times as high as that of the freestream air due to combustion, the inlet was in the started condition despite the high pressure. This improved started condition was attained by using the ramp to increase the pressure in the inlet.