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

摘要： 为了研究超燃冲压发动机总体性能一维计算方法，采用一种新的热力喉道计算方法，由燃烧室出口开始沿上游依次进行声速截面假设，利用流量方程、能量方程及总静压方程计算出该截面所有一维参数，再利用解析方法，计算该假设截面的临界燃烧效率梯度，并由此给出热力喉道判断条件，求出热力喉道的位置。用该方法分别对马赫数3.5~6飞行条件下的发动机模型进行了计算，并与传统方法的计算结果进行对比，结果表明:该方法能够快速计算热力学喉道，具有良好的可行性，与传统方法之间的误差均在6%以内。

关键词: 超燃冲压发动机；热力喉道；总体性能预测