塞式喷管底部压强模型

为了工程计算的需要，首先分析了已有的底部压强计算模型，找出了影响底部压强的主要因素，即塞锥出口截面的压强、马赫数，塞锥出口倾角和底部二次流流率；然后根据数值计算得到的底部压强和冷流实验测出的底部压强，分别拟合底部压强与塞锥出口压强和马赫数的关系式，底部压强与塞锥倾角的关系式，底部压强与底部二次流流率的关系式，最后把这些关系式几何平均得到了所有这些因素与底部压强的关系式。与实验数据比较，该拟合公式不但很好地反映了底部压强的变化规律，而且能够满足工程估算的需要。

Base pressure model of plug nozzle

Base pressure models were analyzed and main factors influencing base pressure were found, i.e. pressure and Mach number at plug exit, plug exit angle and secondary mass flow rate. Then according to results of numerical computation and cold flow test data, three equations were summarized, which were the correlation among base pressure, pressure and Mach number at plug exit, the correlation between base pressure and plug exit angle, and the correlation between base pressure and secondary mass flow rate. At last, final equation was obtained, which was the geometric mean for three equations. It shows that the final equation can predict base pressure roughly as well as imply the way of base pressure variations with these factors.