Vitiation is one of the major sources of uncertainty in testing combustors. In fact, in real flight conditions, there is no water in the air entering the combustion chamber, whereas the air entering the test model contains water and radicals. This makes extrapolation to flight difficult. As the total pressure required for engine testing is high, typically 10 MPa for Mach 8 flight conditions, a vitiation air heater burning fuels is required to increase the air enthalpy. Since the arc heaters become unstable under high pressure operations, they are not suitable for heating air for supersonic engine wind tunnels. In spite of such limitations, these vitiation air heaters are the only options available for driving engine wind tunnels. In this work, the chemical inhibition effect on flame temperature and ignition due to OH and H2O has been numerically investigated by means of the 2D RANS of the LAPCAT 2 European MR2 scramjet. Finally, theoretically laws have been proposed for the ground to flight data extrapolation.
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