Calculations of Multibladed Rotors in Hover using 3D Euler Methods of DLR and ONERA

Kurzfassung

Two different Euler codes for hovering rotor calculations, developed by DLR and ONERA, are compared and assessed using common computational grids. The test cases are based on the Caradonna- Tung data base and on the new HELISHAPE tests with 4-bladed 7A rotor,scheduled for end of 1995. For all test cases the predicted pressure distributions of both codesare in good agreement. Considering that Euler calculation do not account for viscous effects the predicted surface data also compare well with experiments. A detailed comparison of the wake and tip vortex representation by both Euler methods shows some differences. The strong effects of numerical diffusion on wake resolution are demontrated. It is found that a detailed wake and vortex representation hinders the con- vergence to steady state of the Euler methods, particularly the integrated flow quantities oscillate with iteration.