Research On Mechanism Of Drag Reduction And Efficiency Improvement Of Hydrodynamic Torque Converter With Various Biological Characteristics

Research on Mechanism of Drag Reduction and Efficiency Improvement of Hydrodynamic Torque Converter with Various Biological CharacteristicsAs a new interdisciplinary subject, bionic coupling technology combined with experimental fluid mechanics and computational fluid dynamics method has played an important role in the design, optimization and development in the field of fluid machinery. However, because of the friction loss, shock loss and flow loss etc., the efficiency of the torque converter is relatively low. This paper presents an idea that realizes drag reduction and performance improvement through controlling the flow condition in hydrodynamic torque converter by multiple biological characteristics. The duo-turbine hydrodynamic torque converter widely used in engineering machinery would be taken as the research object, and the research would be carried out in three aspects:bionic non-smooth surface, the dolphin shape bionic blade, fish bionic blade, the specific research works and conclusions are the follows:(1) Comparative analysis among the capabilities of the RANS, DES, and LES models to predict flow and turbulence distribution was conducted to come up with guidelines for hydrodynamic torque converter transient simulation. The DES model has been proved be a feasible method for accurately and efficiently simulating3D unsteady turbulent flow in complex passages. Then, the size and arrangement of non-smooth unit were designed on the shell of pump in the light with the boundary layer structure in turbulent flow of hydrodynamic torque converter, the original model and bionic non-smooth surface model was meshed respectively to meet the requirements of the boundary layer. Under the same magnitude of the grid, two models were simulated by Computational Fluid Dynamics (CFD) codes, the results indicate that the bionic non-smooth surface could largely reduce the wall shear stress, turbulent viscosity, vorticity and velocity, improve current efficiency of hydrodynamic torque converter by1to2percentage points.(2) The traditional stator and first turbine blade in the duo-turbine torque converter were substituted by a dolphin shaped blades. The results show that after the application of dauphin bionic blade, the flow cross-sectional area is gentler, the curvature of the surface smoother, and the transverse pressure gradient decreases, the intensity of second flow weakens, the shock loss would be reduced, and the current efficiency of hydrodynamic torque converter would be improved by1to2percentage points.(3) Spanish mackerel, herring, tiger shark, carp, yellow croaker, scavenger were taken as the scanning object, through the processing of reverse engineering,3D data parameters of fish body and some of its detailed features were established as the mathematics model. According to the structural characteristics of hydrodynamic torque converter of each blade, the corresponding new polynomial distribution scheme was presented respectively, the thickness function expressions were also established. Torque converter blades were generated through a compiled MATLAB code without changing the internal and external ring shape, the position of inlet and outlet, blade angles and other parameters. Then, the performance characteristics of the bionic blades were concluded. After that, the bionic blade group which composed of the second turbine blades made by Spanish mackerel, stator blades made by shark, first turbine blades made by scavenger, pump blade made by carp were simulated, the results show the efficiency performance may be increased by1to2percentage points, Rothalpy was used to evaluate the hydraulic loss and the mechanism of drag reduction was analyzed. Finally, the fish morphology, the dolphin shape and non-smooth bionic surface were integrated in this paper to form the hydrodynamic torque converter with multiple biological characteristics, the performance of the existing hydrodynamic torque converter was effectively improved by3to4percentage points.