隔离段尺度效应初探

Preliminary study on scale effect of isolator

随着超燃冲压发动机规模不断扩大,隔离段尺度效应非常突出,利用准一维隔离段分析模型,对3种截面积的矩形截面和圆形截面隔离段的尺度效应进行计算分析。初步结果表明:隔离段入口边界层发展情况是影响压力分布及隔离段长度的重要因素;在给定的压升条件下,相同尺度的圆形截面隔离段比矩形截面隔离段长;隔离段长度不与入口水力直径呈线性关系,即隔离段长度不能几何缩比;隔离段尺度越大,尺度影响越显著。

As the Scramjet engine becoming larger, the scale effect of isolator became remarkable. By using the quasi-one-dimensional model of isolator, the scale effects of the isolator with the rectangular and circular sections including three cross-sectional areas were evaluated numerically.The preliminary results show that the growth of entrance boundary layer significantly affects the pressure distribution and the length of isolator.Under the condtion of given pressure rise, the circular isolator is longer than the rectangular isolator if the scale is same.The isolator length is not linearly related to the entrance hydraulic diameter, which indicats that the isolator length can t be geometrically scaled with the engine size.The larger the isolator scale, the more signicant the scale effect.