Regression study of scramjet nozzle performance on contour parameters

In order to study the influence rules of contour parameters on the performance of cubic curve shaped scramjet nozzle, contour parametric study was conducted by introducing methods of uniform design and regression analysis, and the regression model of scramjet nozzle performance with contour parameter was obtained. The results show that most contour parameters have interactive influence on nozzle performance, but the influence of lower wall height on nozzle lift characteristic could be neglected. Meanwhile, the thrust performance could be improved with the increase of the lower and upper wall exit height. Upper wall length has positive influence on lift performance, contrary to upper wall exit height and angle. The upper wall exit height's correlation with pitch moment performance is similar to lift. The upper wall inlet angle has positive correlation with pitch moment performance while outlet angle has negative correlation in most situations. And within certain range of lower wall's curtailment, it has no significant effect on upper wall pressure distribution.