Vortex System Reconstruction and Cavitation Flow Field Analysis of Hydraulic Torque Converter Stator Under Extreme Operating Conditions

Under extreme working conditions, cavitation is easy to occur near the wall of the hydraulic torque converter stator blade, which will cause the three-dimensional vortex flow field structure inside the flow channel to be unstable and induce fluid energy loss, resulting in reduced working performance. It has important scientific research significance for optimizing the geometric parameters of stator blade and improving the performance of hydraulic torque converter to intensive study the evolution law of cavitation flow field of the hydraulic torque converter stator and its hydrodynamic characteristics of spatial vortex system. In order to accurately identify the cavitation characteristics of the stator and accurately reconstruct its internal three-dimensional vortex structure, the flow field of hydraulic torque converter under stall condition is simulated based on computational fluid dynamics, and the difference between the two calculation results considering cavitation and not considering cavitation model is verified by external characteristic test. Relying on ΩL vortex recognition theory, the threshold value of 0.52 is selected to reconstruct the three-dimensional vortex structure of the stator flow channel using different simulation methods, and the evolution law of cavitation flow field is revealed from the perspective of qualitative and quantitative analysis by combining the intercepted two-dimensional torus flow velocity field, pressure field, turbulent kinetic energy and other calculation results. The results show that: 1. The coupling calculation method of turbulence model and cavitation model has high calculation accuracy, and the prediction error of external characteristic parameters is less than 3%. However, the simulation prediction results without considering cavitation model have large errors. Especially the prediction error of the moment coefficient of pump is more than 20%, and the simulation results are seriously distorted. 2. The three-dimensional vortex structure is reconstructed by ΩL method with high efficiency, and cavitation phenomenon attached to the suction surface of stator blade head under stall condition is obvious, showing a conical distribution situation, and the liquid flow is induced by the phase change of cavitation fluid along the head of stator with large curvature rapid cylindrical flow movement, causing multi-scale vortex collision and fragmentation resulting in instability of the flow field structure, resulting in increased turbulent kinetic energy and local flow energy loss. The research results can provide some technical guidance for the structure optimization and cavitation suppression of hydraulic torque converter.