高马赫数层流摩阻数值计算精度

飞行器在高空高速飞行时黏性效应显著，摩阻预示精度对飞行器的关键气动性能意义重大。目前，摩阻预示主要依赖数值计算，但高马赫数层流摩擦阻力计算与试验测量结果仍存在差距。以具有高速飞行器典型部件特征的球锥、三角翼为对象，结合风洞试验摩阻测量结果，使用国家数值风洞（NNW）数值计算软件和自研CFD程序研究了数值计算中影响摩阻计算精度的格式数值耗散及壁面温度边界条件等重要因素。研究结果表明：数值耗散越小，表面摩阻的计算精度越高；在速度较低的边界层近壁区内关闭熵修正，将有助于提高表面摩阻的预示精度。此外，在高马赫数流动问题的数值模拟中，壁面温度条件对表面摩阻计算同样具有重要影响。最后，基于分析结果和工程需要提出了对高精度摩阻数值预示的研究需求。

Friction numerical calculation precision in high Mach number laminar flow

The prominent viscous effect of vehicles flying at a high speed and altitude leads to the necessity of precise skin friction prediction for the key aerodynamic performance of the vehicles. However, the skin friction obtained from numerical calculation, currently the main approach to skin friction prediction, has a large gap from that of the tunnel test in the high Mach number laminar flow. The key factors influencing friction numerical prediction precision such as numerical dissipation of the space scheme and wall temperature boundary conditions were studied. With typical characteristics of high speed vehicles, a cone with a sharp nose and a delta wing were investigated considering the tunnel test results in the study. The results showed that less numerical dissipation results in more accurate skin friction calculation, and that closing the entropy fix in regions near the wall in the boundary layer helps to improve the calculation precision of skin friction. Additionally, the wall temperature boundary conditions also have an important effect on the skin friction calculation in the high Mach number flow. Finally, the requirements for high-precision skin friction numerical prediction are proposed based on the analysis results and engineering demands.