关键词: 超燃冲压发动机；热力喉道；总体性能预测

Abstract: Determining the thermal throat in the scramjet combustor is one of the key steps to predict the overall performance of the scramjet engine，and thus accurately locating the thermal throat is of great importance in the scramjet performance evaluation.A new approach to predict the thermal throat is presented. The prediction of the thermal throat starts with the combustor exit，and then proceeds upstream by assuming Mach number as unity at each cross-section.The equations of mass flow conservation，energy conservation and gasdynamic function in terms of pressure are solved simultaneously to obtain all one-dimentional gasdynamic parameters at the cross-section.Besides，the critical gradient of combustion efficiency is computed using an analytic method，and subsequently the judgement condition for the thermal throat is given. Then the thermal throat position can be located. The new approach was applied to the scramjet model in the flight conditions from Ma =3.5 to 6. Comparing with the results of the traditional method，it shows that the new method can quickly calculate the thermal throat with good feasibility and the error between the traditional methods is less than 6%.

Key words: Scramjet；Thermal throat；Overall performance prediction