Advanced CFD-based Optimization Methods Applied to the Industrial Design Process of Airframe Components at Airbus Helicopters

For a utility helicopter like the EC135 which features a backdoor to enable rear loading, one of the large drag contributing components is found to be the helicopter aft-body area. In the current study, an efficient automatic adjoint-based optimization method for drag reduction has been successfully applied to the design process of fuselage backdoor geometries at Airbus Helicopters Germany. In the first case, the method was applied to a manually preoptimized EC135 backdoor geometry, where the local drag on the backdoor could be further reduced significantly. In the second case, a retrofit geometry was generated with the same method for the serial EC135 backdoor geometry to decrease drag. Since only outboard deformation was allowed during the optimization, the obtained retrofit solution could be provided as an add-on for EC135 helicopters in service to increase their performance. In both cases, the benefits of the optimization study were confirmed by wind tunnel test results.