OPTIMIZATION OF MICROTURBINE AERODYNAMICS USING CFD, INVERSE DESIGN AND FEM STRUCTURAL ANALYSIS (2ND REPORT: TURBINE DESIGN)

摘要

In this second report, a new aerodynamic design is presented for a radial turbine stage of a microturbine engine. To optimize three-dimensional (3-D) flows, an inverse design method, in which 3-D blade geometry is numerically obtained for specified blade loading distribution, has been applied together with numerical assessment using CFD (Computational Fluid Dynamics) and FEM (Finite Element Method). The runner blade profile along the hub surface was modified to attain nearly radially arranged blade elements especially at the exducer part of the radial turbine in order to achieve required structural strength. Also the blade thickness distribution was optimized to avoid vibration resonance and to meet creep strength requirements. The blade profile along the shroud surface was optimized via 3-D inverse design and CFD. CFD predicted aerodynamic performance of the modified turbine runner was confirmed to be similar, to that of the fully 3-D blade shape, while maintaining structural reliability. The turbine nozzle also has been re-designed by using the inverse design method, with stage performance improvements confirmed by stage calculations using CFD.