The actuation boundary condition for flow control in the DLR TAU Code

Kurzfassung

This report is dedicated to the implementation and the testing of a new boundary condition in the DLR TAU code for the simulation of synthetic jets for active flow control. The work was performed in the joint DLR-ONERA project SIMCOS (Advanced Simulation and Control of Dynamic Stall). A detailed mathematical description of the different versions of the actuation boundary condition and details of the implementation are given. The actuation boundary condition provides a method for prescribing constant-in-time and time-dependent synthetic jets in the incompressible and in the compressible flow regime. The turbulence quantities of the jet can be prescribed based on findings from experimental investigations. The synthetic jet boundary condition allows actuation via blowing, via suction and via zero net mass flux jets. The time-dependent actuation behaviour can be pulsed or harmonic. The issue of geometry modelling and mesh design is also discussed. The results show that the actuation slot should be taken into account in the CAD model. The use of hybrid universal wall functions is proposed as an approach to simplify the grid generation and to save mesh point in the region of the actuation slot. Finally the method is applied to the OA209 helicopter rotor blade at a static incidence angle beyond stall and to a harmonic pitching motion at deep stall conditions.