用干扰剪切流理论改进高Re数内外绕流计算方法及新一代PNS软件研发

The core contents of using interacting shear flow(ISF) theory and interacting shear perturbed flow(ISPF) theory presented by the applicant to improve the method of computing high Re number flow over bodies: using ISF equations to solve of the inner/outer flow over bodies and using ISPF equations to solve laminar perturbed flow and predicting transition location by coupling with experimental data; ISF/ISPF equations system is complete and self-consistent, the improved method is original. The improved method avoids some unreasonable treatments including in computational methods in common use: the RANS, RANS/LES equation method and the traditional PNS, method that forms the basis of an industry-standard aerodynamic computations, these unreasonable treatments are mainly using boundary layer stability theory to compute perturbed flow of the inner/outer flow over bodies and to predict transition location by coupling with experimental data and suppose that the earliest transition occurs always in the classical boundary layer. The ISF theory that has been applied proves that the laminar flow of the inner/outer flow over bodies is a complicated ISF. The earliest transition occurs always in this complicated ISF . The ISF- and ISPF- equations are respectively the same kind equations of the well-known PNS- and PSE- equations. Numerous numerical results of using PNS to compute ISF are good consistent with those NS equations and that the numerical results of using PSE to compute boundary layer stability are good consistent with those of DNS of boundary layer show that using ISF/ISPF equations to compute the laminar flow and its perturbed flow of the inner/outer flow over bodies is reasonable and feasible and can give approximately the results of DNS of the laminar flow. The equation theory that using these equations to compute the laminar flow of the inner/outer flow over bodies under coarse grids can give approximately the result of DNS of the laminar flow has initiate meaning. This project is aimed at supersonic and hypersonic high Re number inner/outer flow over bodies and develops and examines two improved RANS method and PNS methods and develops new PNS- code that not only is more reasonable, but also useful.

利用申请人提出的干扰剪切流（ISF）和扰动流（ISPF）理论改进高Re数内外绕流计算方法的核心内容是：用ISF方程计算绕流层流基本流，用ISPF方程计算层流扰动流并预测转捩，该方程体系完备自洽，为原创方法。改进方法避免了绕流计算常用RANS/LES等方法和工业标准气动计算PNS方法中用边界层稳定性理论计算层流扰动流并预测转捩且假定转捩最早发生在边界层中等不合理处理。ISF理论证实绕流层流为一复杂ISF，转捩最早发生在该ISF中，ISF和ISPF方程分别与PNS和PSE为同类方程；PNS解与NS解一致和PSE计算边界层稳定性给出与边界层直接数值模拟（DNS）结果一致的众多计算证实：ISF/ISPF方程计算绕流层流可行，且可给出与层流DNS结果一致的结果，近似层流DNS结果的方程理论具有开创性。本项目针对典型的高速内外绕流问题，发展和验证改进的RANS和PNS方法计算，并研发新一代PNS软件。

高雷诺(Re)数流动在自然界和许多工程技术领域中普遍存在。对它的研究也因此具有实际工程需要和科学意义。当高Re数流动存在近似主流方向时, 在主流方向上扩散与对流效应相比很小,可近似加以忽略, 即对主流方向坐标变量求偏导的粘性诸项可以从方程组中略去,于是得到扩散抛物化(DP) 方程组。在此工作基础上，项目提出了计算高Re数层流-转捩-湍流全程流动的新一代PNS方法，即在层流区计算ISF（即PNS）方程，同时计算ISPF（即PSE）方程并结合试验资料计算出转捩位置，之后计算湍流ISTF（即PRANS）方程。DPNS方程组可采用空间推进方法求解，即在主流方向扫描一次或几次。这样，相对于时间迭代法而言，计算速度可提高1-2个量级，存储量也大大降低，从而可提高 CFD解决实际工程问题的效率。根据这些算法，项目还发展了ISF（PNS）/ISPF（PSE）/PRANS 空间推进计算软件，对超声速和高超声速高 Re 数内外绕流进行验算和确认，开展 ISPF（即 PSE）方程计算 ISF 稳定性，并与相应实验结果作比较研究。这些研究有利于层流-转捩-湍流流动机理的探索, 为前沿科学研究和工程需求提供科学计算基础。