A method for evaluating the combustion efficiency in direct-connect supersonic combustion pulse facilities

A method for analyzing supersonic combustion tests which takes into account the 3-D character of the flow at the combustor exhaust is presented. By this method, the efficiency of hydrogen combustion in a Mach 3, high-enthalpy air flow was evaluated under a variety of operating conditions. The experimental tests were conducted using a direct connect supersonic combustion pulse facility fed with vitiated air at 2 MPa and 2400 K. The combustion efficiency was evaluated on the basis of detailed pressure and Mach number maps on the combustor exhaust area. The Reynolds Analogy was used to model the heat losses at the tunnel walls. A large number of combustion tests were analyzed to evaluate the effectiveness of different flame stabilizers, placed either on the tunnel walls or in the flow core. Increments of the overall equivalence ratio (varied within the range 0.2 - 1) were found to improve the combustion efficiency. Nearly all tests with equivalence ratio above 0.6 gave combustion efficiencies in the range 0.5 - 1.