轴对称收敛-扩散喷管几何参数优化设计

现代航空发动机广泛采用机械可调收敛—扩散喷管,以适应其宽广的工作范围。当发动机工况改变时,要调节排气喷管的出口面积.以获得尽可能高的内特性,此时喷管的其它几何参数也随之改变。喷管各几何参数对内特性的影响可以通过模型试验获得,而可调喷管模型的加工和试验周期长且非常昂贵。因而喷管研制中必须首先对喷管内特性的影响综合考虑,得到最佳的折衷方案,为喷管设计提供依据。喷管的推力系数是衡量喷管内特性的最重要的参数.是喷管设计的主要指标,因而选取推力系数作为优化设计的目标函数。

OPTIMUM DESIGN FOR GEOMETRIC PARAM ETERS OF AXISYMMETRIC CONVERGING DIVERGING NOZZLE

A mathematical model of a axisymmetric converging-diverging nozzle in design conditions is set up by quadratic-regression equation. The thrust force coefficient is taken as objective function. The three geometric parameters (half convergent angle, half-divergent angle, radias ratio of throat curvature to throat) are chosen as design variables. The optimum design is completed py the random-walk method. Then the relationships of the optimum geometric parameters to the designed pressure ratio of the nozzle are obtained. The results provide the basis for designing the axisymmetrie convergent-divergent nozzle of an exhaust system.