液力变矩器非定常空化特性及其抑制技术研究

In order to accommodate to the increasing power-density requirement, the fluid velocity in torque converter has been increased, leading to higher risk for cavitation. Cavitation in torque converter may bring about severe performance degradation, noise, vibration or even erosion failure, which deteriorates vehicle performance, durability and driving comfort. Thus research on the transient cavitation behavior in torque converter and cavitation suppression techniques was proposed. A computational fluid dynamics (CFD) model will be built to simulate the cavitating flow. The model fidelity would be increased by modifying the numerical model settings through torque converter characteristics test and pressure measurement. The cavitation type and its revolution process under various operating conditions and charge oil conditions could be investigated by CFD models in conjunction with torque converter tests. The investigation into the cavitation mechanism and inception condition could help to introduce cavitation suppression techniques. Based on torque converter cavitation characteristics, the passive cavitation suppression approach, such as surface modification and secondary flow passage, could be put forward, and the active cavitation control technique, which is mainly based on charge oil condition manipulating, could be proposed to inhibit the development of cavitation in torque converters and enhance torque converter performance. The proposed study is able to improve torque converter design and promote the development of advanced hydrodynamic transmission design theory.

为满足车辆动力传动系统向高功率密度发展要求，液力变矩器内流速越来越高，导致容易产生空化。液力变矩器中空化的产生能导致性能恶化、噪音、振动甚至气蚀失效，严重影响车辆动力性、驾驶舒适性和可靠性，因此本项目提出液力变矩器非定常空化特性及其抑制技术研究。采用液力变矩器宏观特性试验、微观压力点测试以及空化流动数值计算相结合的方法，建立适用于液力变矩器内空化流的计算模型，提高空化预测精度；通过实验和数值计算研究空化在液力变矩器不同工况、补偿油条件下的形态及其演变规律，揭示液力变矩器空化发生机理和流体动力学条件，为空化抑制提供理论指导；针对液力变矩器空化特性，提出基于表面处理、二次流道等技术的被动空化抑制方法，及基于补偿油条件控制的主动空化抑制技术，以抑制空化产生，提高液力变矩器性能。这些问题的深入研究与解决对提高液力变矩器的设计水平、推动液力传动设计理论的发展具有重要意义。

随着车辆动力传动系统向着高速化和高功率密度方向发展，液力变矩器内流速越来越高，导致容易产生空化。空化会导致变矩器性能恶化、噪音、振动甚至气蚀失效，严重影响车辆动力性、驾驶舒适性和可靠性。本项目采用试验研究、数值模拟和理论分析相结合的方法，开展了液力变矩器非定常空化特性及其抑制技术的研究。建立了液力变矩器空化计算流体动力学模型，并结合实验数据对模型进行了修正，实现了变矩器空化的高精度预测，开展了有、无空化液力变矩器的稳态/瞬态数值及实验研究，形成了液力变矩器空化程度评价指标。通过空化对液力性能影响机理的研究，以及不同工况下的液力变矩器空化演变特性分析，确定了空化工况区间及其形成机理，完成了空化与叶轮交互效应影响关系研究。基于液力变矩器的空化形成条件及演变机理，获得了不同叶轮转速、补偿油温及油压等工况条件下液力变矩器空化的特性规律，提出了相应的主/被动空化抑制技术。项目研究成果对提高液力变矩器的设计水平、推动液力传动设计理论的发展具有重要意义。