利用渗透边界模型分析三维内转式进气道启动性能

Investigation of Starting Performance of a 3D Inward Turning Inlet through Fixed-Exit Bleed Model

进气道抽吸区域一般包含大量抽吸孔,这些抽吸孔的网格前处理异常繁复、离散求解及CFD仿真困难。为避免这些问题,利用集成了渗透边界模型的数值仿真软件AHL3D模拟小孔抽吸,获得了小孔抽吸对三维内转式进气道Ma4~6内的启动性能的影响。结果表明:同等条件下,渗透边界与抽吸孔仿真的机体侧壁面压力曲线基本重合,且进气道喉部参数最大差别小于1.5%,说明利用渗透边界模型研究抽吸对进气道启动性能的影响具有可行性;边界层抽吸位于分离泡最高压力点附近时,可实现进气道宽马赫数范围(Ma4~5.5)的启动;Ma5条件下,开孔率在0.1左右,进气道实现启动,且启动后流量抽吸率低于1%;抽吸背压为6.5倍来流静压时,进气道实现启动,启动后流量损失几乎为0,压力分布规律与远场初始化得到的启动流场完全一致。

Inlet＇s porous bleed system always contains a lot of holes, these holes＇ grid preparation is ex- tremely complicated, it＇ s hard to resolve each discrete hole and simulate through Computational Fluid Dynamics （CFD）. In order to avoid these problems, CFD software AHL3D which integrated the fixed-exit bleed model （FEBM） was used to simulate porous bleed system. An inward turning inlet＇ s starting performance at a range of Ma4 - 6 was achieved using bleed holes. The results indicate that, under the same condition, the pressure ratio distribution of inlet＇ s body-side derived from FEBM is the same with porous bleed system. The maximum differ- ence of flow parameter at throat is below 1.5%, which demonstrated that it＇ s practical to use FEBM to evaluate the influence of porous bleed system to inlet＇ s starting performance. When the bleed region located near the peak pressure point of separation bubble , the inlet could be started at a wide Maeh number range from 4 to 5.5. When Mach number is 5, the plate porosity is about 0.1, the inlet could be started and the minimal mass flux bleed ra- tio is below 1%. While the porous bleed system plenum pressure is 6.5 times the far-field pressure, the inlet is started and the minimal mass flux bleed ratio is almost 0, the pressure ratio distribution agrees well with the re- sult from flow-field derived from far-field initial method.