变截面隔离段流场数值分析

Numerical analysis of a variable cross-section isolator

对一种由矩形转变为圆形的变截面隔离段流场进行了数值模拟,并将其与圆形和矩形等截面隔离段内流场进行了对比。在相同来流条件和不同进出口压比条件下,分析了隔离段内激波串区域流动特性、激波串起始位置、激波串长度、出口处流量平均参数以及隔离段出口流场流动均匀性等隔离段性能。结果表明:相对于矩形截面隔离段,变截面隔离段中的分离区域有变短、变宽的趋势。这不仅能够有效降低激波串长度和内阻,而且产生了主流和壁面之间的横向流动。最后,对变截面隔离段中激波串长度与压比之间的关系公式进行了修正。

The flow characteristics of a variable cross-section isolator were investigated using numerical simulation. The cross-section of the isolator was designed to have linear transformation from rectangular entrance to circular exit and all crosssection areas remained constant axially. The identical incoming flow and different pressure ratios were considered. The numerical results were compared with that of circle and rectangle cross-section isolators by characteristics of shock train region, leading edge of shock train, length of shock train, mass weighted-average parameters at the exit, etc. In contrast to rectangle cross-section isolator, the shorter and wider separation region is achieved in the variable cross-section isolator, which leads to shorter length of shock train, decreased internal drag and lateral flow between mainstream and wall. Based on an analysis of shock train length in this variable cross-section isolator,a modified correlation is proposed.