Dimensional Ns Equations Numerically Solved And The Sa Turbulence Model Applied Research

There is an urgent requirement for accurate, efficient and easy-used aerodynamic data and flow-fields analysis tools. However, the Euler codes are not satisfied all the demand for simulating the complex flow-fields. More powerful method of solving Navier-Stokes (N-S) equations are required for simulating viscous effect to get more accurate and detailed information about flow-fields. In addition, most flows in nature and practice of science engineering are turbulence, so our work on the simulation of complex-flows will have to be related to turbulence.The N-S equations are solved based on the central finite volume method and explicit four stages Runge-Kutta time stepping scheme, and the one-equation Spalart-Allmaras turbulence model is solved decoupled from N-S equations. The present work is mainly focused on the following aspects:1. Solving the elliptic grid generation together with an algebraic method marching along the normal-to-wall direction, viscous grids around complex geometries are generated. The inner-layer grid generated with the algebraic method is orthogonal and easy to control the distance to the wall. According to the Hilgenstock's method, the source items are calculated to control the orthogonality and spacing of the grid lines on boundaries.2. The modified central difference method with artificial viscosity by Jameson is studied in spatial discrete about the convection terms of the N-S equations. In order to apply the central scheme to higher Mach number flows, the sensor about pressure is modified with some TVD-like properties, as a result, it decrease the untruth numerical vibration effectively, and broaden the application extent of the centered difference format. An explicit four stages modified Runge-Kutta time stepping scheme is used to solve 3-dimensional compressible N-S equations. The explicit method is widely used for its simpleness and little memory consumed. With local time step andimplicit residual smooth method, the convergence procedure is accelerated.3. The one-equation Spalart-Allmaras model is applied to simulate turbulent flows. In order to solve the equation of S-A turbulence model with finite volume method, the conservative form of S-A equation is derived from it's original form. The S-A model can predict the attached and separated flows, and no higher resolution near-wall grid is needed, so the code of solver can be programmed easily.4. Many test cases are calculated to verify the above study. Such as 2-dimensional airfoils (NACA0012 and RAE2822), ONERA M6 wing, NASA TN D-712 wing-body standard model, DLR-F4 wing-body model are simulated for low speed, subsonic and transonic turbulent flows. The S-A computed results are compared with Algebraic B-L model and show good ability of separated flows simulating.