Duct Design in Subsonic and Supersonic Flow Regims with and without Normal Shock Wave using Flexible String Algorithm
Abstract. In this investigation, the Flexible String Algorithm (FSA), used before for inverse design of 2D subsonic ducts, is developed and applied for inverse design of subsonic and supersonic ducts with and without normal shock wave. In this method, the duct wall shape is changed under a novel algorithm based on deformation of a virtual flexible string in a flow. The deformation of the string due to the local flow conditions resulting from changes in wall geometry is performed until the target shape satisfying the prescribed walls pressure distribution is achieved. The flow field at each shape modification step is analyzed using Euler equation solution by the AUSM method. Some validation test cases and design examples in subsonic and supersonic regimes are presented here which show the robustness and flexibility of the method in handling the complex geometries in various flow regimes. In the case of unsymmetrical ducts with two unknown walls, the FSA is modified to increase the convergence rate significantly. Also, the effect of duct inlet and outlet boundary conditions on the convergence of the FSA is investigated. The FSA is a physical and quick converging approach and can efficiently utilize flow analysis codes as a black box.