Development of a coupled 2-D panel / Navier-Stokes solver for numerical analysis of transonic flow

Abstract

Numerical methods for aerodynamics analysis have been popularly researched and now provide an accurate result. However, they still have shortcomings. Euler and Navier-Stokes solver needs large number of grids and high-order scheme to minimize dissipation and diffusion errors. This causes huge computing time and resources. Panel Method is very fast. However, it cannot simulate viscous flow and has difficulty in transonic flow analysis. The purpose of the present research is to examine capability of hybrid method in compressible, transonic, unsteady, vortex, and viscous flow simulation. Additionally, the author aims to develop a coupled Panel/Navier-Stokes solver with small grid domain size, which is fast and accurate. The fundamental idea to the coupling method is that Navier-Stokes solver can calculate the flow accurately even with very small grid if the boundary condition is well-imposed. The boundary value is obtained by using the Panel method. The Panel method was coupled with the Euler/Navier-Stokes solver by providing induced velocity to boundary conditions. Afterwards, the surface potential of the panel is determined by using a Bernoulli equation and pressure information from the Euler/Navier-Stokes solver. Additionally, a linearized potential equation and a transformation method were used to correct compressibility effect to the Panel method. Steady incompressible, subsonic compressible, transonic, unsteady, vortex and viscous flow were simulated respectively, and the coupling method was tested with reduction of grid domain size. The results showed that the idea was correct, and the capability of the coupling method in transonic flow was proved. Also, a moving vortex was also well-simulated by using only induced velocity as boundary condition. The grid domain size could be reduced to 0.1 chord in the incompressible flow, 2.5~5 chord in transonic flow, and 1 chord in viscous flow. Consequently, the computing time was saved to 1/5~1/30 compared with that b...