Supersonic cooling film flow evolution on a curved wall under hypersonic flow

Abstract

Curvature plays a crucial role in evolving supersonic cooling film flow-field structures. Flow-field structural images were captured using nanotracer-based planar laser scattering,, and wall pressure values were obtained using experimentally validated numerical simulations. A supersonic cooling film is tangentially injected at the Mach number of Maj = 2.3 into a laminar boundary layer at a mainstream of Ma = 6. The supersonic cooling film inhibits mixing-layer instability on the convex curved wall (CV) and promotes it on the concave curved wall (CC). After increasing the total incoming pressure, the reduction ratio of static pressure (RSP) between the supersonic cooling film and the mainstream flow causes a delay in the position of the mixing-layer instability, smaller-scale vortex structures, and decreased flow velocity of the typical vortex structures on the CC and CV. The wall pressure increases for the CV and decreases for the CC, indicating that the supersonic cooling film suppresses the changes in wall pressure due to curvature. The supersonic cooling film suppresses the decrease in the impulses for bulk dilatation (Ip) due to convex curvature and the increase in Ip due to concave curvature. The growth rate of Ip on the CC increases from −15% to −8% and decreases on the CV from 31% to 12% in the bending impulse (IΦ) range of |IΦ| = 1.337–3.624 for a total inlet pressure of 0.5 MPa. Increasing the RSP could control the Ip values on curved surfaces more effectively. The results of this study can be applied to cooling the infrared optics window on hypersonic vehicles.

Flow evolution of mixed layer on convex curvature wall under hypersonic conditions

“…NPLS的结果可以很好地反映流场的时空演 化规律, 但对流场结果得到定量分析, 一般采用分 形分析 [3,27] 来研究流场结构的演化规律, 以分形维 数作为分形度量的一种重要参数. 本文采用计盒维 数方法, 首先采用Canny边缘检测 [3] 滤波算和当 地阈值法对数字图像进行处理得到流场精细结构 的边缘检测结果, 边缘检测结果如图5所示.…”