Redesign Of Turbomachinery Blade Using A Viscous Inverse Method On S1 Surface

Turbomachines have been widely used in various national economy departments.Their working principle is based on the energy conversion between blades and fluid.This implies that an efficient and fast blade design method is the key point to improve the operation efficiency of turbomachinery.This thesis develops a viscous inverse method based on S1 surface theory and performs inverse deigns for different types of the turbomachinery in order to reduce the aerodynamic loss and thus enhance the efficiency.The flow fields on the S1 surface are solved using the MISES code and by specifying a reasonable distribution of the steamtube thickness of section profiles.Results are compared using three dimensional calculations to validate the precision.Reasons for errors are also analyzed.During the inverse design process,the pressure distribution was modified through the "mixed-inverse" mode.In addition,a temporarily "frozen" boundary layer scheme was employed to enhance the robustness and accelerate the convergence.During the redesign for centrifugal impeller blades,the pressure distribution at 10% and 90% span were modified using fore-loaded,through reducing the slope of pressure change on the blade suction side surface.This is intended to reduce the strength of the shock wave and to enlarge the leading edge load at the same time.Results indicated that the working range of the redesigned blade was shifted to larger mass flow point and the high efficiency region was significantly extended,when compared with that of the original geometry.Meanwhile,the secondary flow at the exit of the impeller was significantly reduced,and the intensity of the shock wave at the blade leading edge near the shroud was apparently decreased.To redesign centrifugal impeller with splitter blade,the pressure on main blade pressure side was modified through weakening the influence of the splitter blade leading edge,and parts of the load for splitters are transferred to the main blades.The low velocity region at the impeller exit is reduced slightly,as well as the relative Mach number at the leading edge of the splitter blade.Later,inverse design is carried out for vaned diffusers.The pressure gradient at the semi-vaneless space of suction side was enlarged using fore-loading,and a smooth pressure gradient at the middle-rear part of the blade was maintained.This narrows the low speed/reverse flow zones at rear region of pressure surface.Then,a three dimensional vaned diffuser design method based on the S1 surface theory was studied.The 3D diffuser blade was modified to match the nonuniformity of impeller exit flow angle.At large mass flow rate,the designed blade improved the compressor performance greatly,while distortions appeared near the blade tip at small mass flow rate.Reasons for the distortion were analyzed through coordinate transformation for the section profiles and some design principles were presented.Finally,the axial turbine rotor blade is optimized using inverse design.The pressure recovery gradient was reduced through eliminating a pressure step on the suction side at the cascade exit.This helps to reduce the shock wave intensity and the loss induced by the shock-wake interaction.The efficiency at low back pressure is improved and high-efficiency range is extended for the studied turbine..The above designs for different kinds of blades validate the feasibility and applicability of the developed inverse method.This is valuable for improving the design system for turbomachinery blades.