变截面隔离段流场数值分析

Numerical analysis of a variable cross-section isolator

关键词:  内流空气动力学  变截面隔离段+  激波串+  冲压喷气发动机

Key words:  Internal aerodynamics  Variable cross-section isolator+  Shock train+  Ramjet engine

摘要:

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。

Abstract:

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 cross-section 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.