Investigation of an alternative approach of time accurate polar calculation

Abstract

Currently, the standard method to compute lift and drag polars of 2D profiles, 3D wings, and complete aircraft configurations is to perform a several number of steady simulations at angles of incidence along the polar range.. In general, RANS methods with a one equation or two equation turbulence model were applied. For regular flow topologies with no or only small separation areas this choice is the most efficient and leads to good accordance with experimental data. However, in complex high lift configurations big separation areas can occur even at low angles of attack in the linear polar regions, forcing unsteady effects and limiting the applicability of steady methods. It can be necessary then to apply time-accurate methods to resolve this unsteadiness in order to achieve more reliable results. In the present work a time-accurate polar calculation approach was investigated, in which the URANS method with a Reynolds-Stress-Model is coupled with a motion module to continuously increase or decrease the angle of incidence every physical time step.