Visual Investigation On Cavitation Phenomenon Of Oil At Different Temperature In V-shaped Hydraulic Valve Orifices

As an important part of modern industry,hydraulic technology plays an indispensable role in promoting China's economic development and technological progress.In the actual use of hydraulic technology,cavitation is easy to occur at the throttle valve,slide valve and other valve ports,especially in the case of small opening,which seriously affects the control accur-acy of the hydraulic system,accompanied by strong vibration and noise.At present,the resea-rch of cavitation phenomenon is mostly focused on the water medium,and the influence of oil temperature on cavitation is not considered in the research of cavitation with hydraulic oil as medium.There are essential differences in physical mechanism between water cavitation and oil cavitation.Water cavitation is vaporous cavitation of phase change,oil medium is gaseous cavitation.In this paper,the characteristics of gaseous cavitation flow in hydraulic valve port are studied,which can improve the cavitation theory with hydraulic oil as medium.In view of the cavitation phenomenon of hydraulic valve port and the inconvenience of three-dimensional experimental model for cavitation research,this paper designs a two-dimensional experimental model with side light injection,and studies the influence of pressure difference and oil temperature on the cavitation of valve port by using the visual experimental method.Experimental found that at the hydraulic valve port,with the increase of the oil temperature,the pressure difference at the inlet and outlet of the initial cavitation decreases gradually,and the variation of the pressure difference also decreases as a whole.The oil temperature and pressure difference of the same incipient cavitation phenomenon are recorded by experiment,the curve fitting data point was used to obtain the Bunsen solubility of 46#hydraulic oil at 298.2k equal to 0.101.There are attached cavitation,cloud cavitation and atomized cavitation in the valve port.Attached cavitation exist periodic oscillations caused by the reentrant jet and intermittent oscillations related to the discontinuity propagation mechanisms,which are uncertain.When the pressure difference is constant,the cavitation volume increases with the increase of hydraulic oil temperature.Oil temperature changes is in the range of 23 ? to 60 ?,the relationship between oil temperature and cavitation volume is approximately linear.When the oil temperature is constant,the cavitation volume increases with the increase of the pressure difference,when the pressure difference changes is in the range of 1.5MPa to 4.5MPa,the cavitation volume and the pressure difference are approximately linearly distributed.The cavitation phenomenon of valve port will appear saturation state,and the pressure difference of cavitation saturation state will decrease with the increase of oil temperature.When the oil temperature is 23 ? and the pressure difference is within 4.5MPa,the saturation state does not appear.When the oil temperature is 30 ?,40 ?,50 ? and 60 ?,the pressure difference at the saturation state is about 4.5MPa,4.0MPa,3.5MPa and 3.0MPa.When the pressure difference is 3.5MPa and the oil temperature changes from 30 ? to 50 ?,the increase of the cavitation volume is dominated by the air released from the oil.When the temperature changes from 50 ? to 60 ?,the mechanism of air release was weakened,and the gas expansion mechanism was enhanced.