Progress in Weak Fluid-Structure-Coupling for Multibladed Rotors in High-Speed forward Flight

Progress in coupling the DLR rotor simulation code S4 and the DLR Navier-Stokes solver FLOWer following a weak coupling approach is reported. The method allows to produce trimmed CFD solutions for rotors in high-speed forward flight with inclusion of elastic blade deformations and viscous effects. The weak coupling procedure is applied to high-speed forward flight test cases of the 7A and the 7AD rotor. Isolated blade computations are carried out for both rotors while the full 4-bladed rotor is simulated only in the 7A case using the chimera approach. The weak coupling which includes the transfer of normal forces, tangential forces and pitching moments from the CFD code to the rotor simulation code improved the agreement with the existing experimental data compared to the uncoupled computations considerably. The performance difference between the 7A and the 7AD rotor in high-speed forward flight is well predicted.

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