AUTOMATIC TRANSMISSIONS: ON THE RELATIONSHIP BETWEEN THE CAVITATION MODES OF THE TORQUE CONVERTER AND HIGH-FREQUENCY RESONANT TORSIONAL OSCILLATIONS OF MECHANICAL COMPONENTS

Abstract

Based on the analysis of foreign publications, a number of new scientific results are presented in the field of hydrodynamics of working fluid flows in torque converters (TC) of automatic hydromechanical transmissions (AHMT), including cavitation in TC, which were obtained using the new CFD (Computational Fluid Dynamics) technology as part of research to reduce the vibroacoustic loading of AHMT. CFD modelling methods have shown that cavitation in a TC, along with the creation of noise and vibration, significantly degrades its characteristics (in the example given, the transformation coefficient is by 18.1 %, efficiency is by 5.8 %, turbine torque is by 20.3 %), and also creates high-frequency oscillations in a wide range that can resonate with the natural frequencies of the AHMT components. The influence of structural and operational factors on cavitation is investigated. The greatest cavitation occurs on the blades of the TC stator in stop mode when the car accelerates from a standstill. The results of CFD modelling are in good agreement with experimental data. CFD technology has become an effective tool for optimizing the design of an automotive TC, its blade system, flow part, visualization of internal flows, study of the mechanism of occurrence and impact of cavitation. The analysis of methods of attenuation of cavitation is carried out, including the selection and maintenance of the value of the TC recharge pressure. The presented provisions in Russian are published for the first time.