Design and analysis of a 11:1 centrifugal compressor for a small turbofan engine

Centrifugal compressors, used extensively in turbofan engines of high range missiles, provide advantages like shorter length, capacity to operate over a wide range of mass flows at a particular rotational speed and handling small volume flows. Fundamental theory for centrifugal compressor design is used for preliminary 1D-design with a goal to achieve pressure ratio of 11:1 and inlet mass flow of 6kg/s using a single stage. MATLAB code has been developed for the optimization of compressor design using evolutionary algorithms with different design variables. The design variables are selected from the control points for Bezier curves. Half of the variables are used for the passage optimization whereas half of them enhance the performance of impeller blades. Once the impeller geometry is optimized, results are used to draw the flow passage, hub and shroud radiuses, axial length of the impeller, and blade height in 2D plane. Thus, theoretical results are verified using the optimization algorithm and aerodynamic analysis using CFD tools in ANSYS workbench. Since blade thickness is critical to the structural loads due to high rpm of the impeller, structural analysis (fluid structure interaction) is performed for the CFD loads being applied on the impeller in order to verify the feasibility of design for the working environment.