Advanced detached-eddy simulation of the MD 30P-30N three-element airfoil

Abstract

An experimental version in the Detached-Eddy Simulation (DES) family (called Advanced DES or ADES) is introduced and tested on a geometry that is fairly complex but two-dimensional. The essential change in ADES is that the user is given control of the regions treated with full turbulence modelling (RANS) and those treated with Large-Eddy Simulation (LES). This zonal character makes the approach more powerful, but less practical, so that in its current state it is not ready for industrial CFD. The grid requirements of the two regions are very different, and multi-block grid structure is natural. Another key feature is a Volumetric Synthetic Turbulence Generator (VSTG), installed to feed the LES region with viable resolved turbulence, so that the resolved Reynolds stresses rapidly substitute for the modelled Reynolds stresses present in the RANS region. The VSTG operates in a volume, rather than on a surface and can be active in attached boundary layers, at a trailing edge, or after separation. The well-known McDonnell-Douglas 30P-30N airfoil is simulated with periodic lateral boundary conditions. The VSTG is successful, and the desired nature of simulation is obtained in each region. ADES involves zonal decisions, but appears robust. An inertial range is clearly indicated in frequency spectra. A grid-refinement study is included, as well as variations in lateral domain size and STG positions; this led to a matrix of 11 simulations. Cases are shown at four angles of attack and with three RANS models in addition to ADES. Pressure and friction distributions and velocity and shear stress profiles are compared in detail. The prospects for an evolution of ADES into a practical routine approach in the long term are discussed.