关键词: 液压油液, 有效体积弹性模量, 初始含气量, 空气分离压, 升压时间

Abstract: In order to predict the effective bulk modulus of air-liquid mixtures of hydraulic oil below the saturation pressure accurately,based on the definition of the bulk modulus and law of mass conservation,according to the air release and cavitation processes, a theoretical model for effective bulk modulus of air-liquid mixtures of hydraulic oil below the saturation pressure was proposed.The numerical calculation results show that the B-p curve of the theoretical model for effective bulk modulus of air-liquid mixtures of hydraulic oil shows good agreement with the B-p curves of published literature's theoretical model and fitted experimental data,verifing the accuracy of the theoretical model,especially the extreme low pressure region below the atmospheric pressure. The effective bulk modulus of air-liquid mixtures of hydraulic oil is more consistent to practical conditions. Furthermore, the effects of initial air content,pressure and pressure rising time on effective bulk modulus were analyzed. The results show that below the saturation pressure area,the effective bulk modulus deceases with the increasing of initial air content， and the effective bulk modulus increases in a narrow range with the increasing of the pressure rising time.

Key words: hydraulic oil, effective bulk modulus, initial air content, saturation pressure, pressure rising time