斜激波入射内凹半圆柱面湍流边界层数值模拟

Numerical Simulation of Incident Oblique Shock Wave Turbulent Boundary Layer Interactions on a Concave Cylinder

关键词:  斜激波  内凹柱面  激波/边界层干扰  流动分离  流向涡对  低能流

Key words:  Oblique shock wave  Concave cylinder  Shock wave/boundary-layer interactions  Flow separation  Streamwise counter-rotating vortex pair  Low-momentum fluid

摘要:

针对三维内转式进气道中的激波/边界层干扰问题，提出了斜激波入射内凹半圆柱面的简化模型，在来流马赫数为6的条件下，采用数值模拟研究了气流偏转角θ=6°~14°的斜激波与内凹半圆柱面边界层的相互作用。结果表明，从上游至下游，斜激波与内凹半圆柱面干扰产生了以扫掠、入射及反射为主要特征的流动结构。斜激波扫掠内凹半圆柱面边界层诱发流动分离，分离激波与入射激波的干扰类型均从马赫反射转变为规则反射，不满足经典扫掠流场的准锥形特征。扫掠过程中产生的不断增厚的低能流向对称面汇聚，并进入由斜激波入射产生的分离区内，使得分离区长度增加。随着θ的增大，分离区的流谱呈现不同的形态，当θ≥10°时，低能流在对称面撞击后形成流向涡对，当θ=14°时，流谱中的旋风涡消失。当入射激波反射后，低能流集中在对称面处，其高度沿流向持续增加。随着θ的增大，内凹半圆柱面出口截面的总压恢复系数减小，而低能流区的总压恢复系数略有增大。

Abstract:

Shock wave/boundary-layer interactions are commonly encountered in the three-dimensional inward-turning inlet. To better understand the flow physics of the interactions， a simplified model called the oblique shock wave impinging a concave cylinder was employed. Numerical simulations were conducted at a freestream Mach number of 6 with a series of θ （i.e.， the deflection angles） ranging from 6° to 14° to investigate the shock wave/boundary-layer interactions on a concave cylinder. The results show that the oblique shock wave/concave cylinder interactions can be characterized by sweeping， impinging and reflection from upstream to downstream. The flow separation occurs since the oblique shock sweeps the concave cylinder. The classical quasi-conical symmetry is lost， since the shock interaction type between the incident shock and the separation shock is transited from Mach reflection to regular reflection. Then the thickening low-momentum fluid converges to the symmetry plane， and enters the separation zone caused by the oblique shock impinging the concave cylinder， which increases the length of the separation zone. With the increase of θ， the separation patterns evolve into different types. When θ≥10°， a streamwise counter-rotating vortex pair forms by the collision of the low-momentum fluid on the symmetry plane. When θ=14°， the tornado-like vortex in the separation pattern disappears. After the shock reflection， the low-momentum fluid converges to the symmetry plane， and its height continually increases along the streamwise direction. With the increase of θ， the total pressure recovery coefficient of the exit of the concave cylinder decreases， while the total pressure recovery coefficient of the non-mainstream increases slightly.