The Study On Gear Pump's Cavitation Characteristics Under Wide Temperature Range And Variable Velocity Conditions

The gear pump is widely used in the industry because of its simple structure,large output,long service life,reliable technology and wide application conditions.The cavitation of the gear pump is an important cause of gear pump failure.The cavitation of the gear pump is mainly caused by the generation of air bubbles inside the gear pump and the collapse of the bubble to cause shock waves.In practice,the cavitation phenomenon will change correspondingly with the change of working conditions.In this paper,the gear pump system used in this paper is facing the actual situation of wide temperature range and large speed change,and the degree of cavitation will change in the system.Therefore,this paper studies the degree of cavitation change of gear pump under different temperature and speed.Cavitation of gear pump is studied from its generating principle and influencing factors,which provides an important reference for subsequent structural improvement and attenuation of cavitation damage.In this paper,the internal flow field of gear pump is modeled by Pumplinx simulation software,and observation points are established to monitor the pressure,where gas content and density of the internal flow field after the change of temperature and speed.Cavitation analysis of internal flow field of gear pump under different working conditions is carried out,with the help of Pumplinx's unique cavitation damage module for empirical judgment.The simulation results compare the internal flow field characteristics and cavitation damage level under different working conditions,and summarize the rule that the cavitation intensity is affected by oil temperature and gear pump speed.The simulation results show that the level of cavitation energy decreases with the increase of temperature and increases with the increase of rotational speed.The influence of relevant factors the level of cavitation energy is verified by experiments.The main contents of t his paper are as follows.The academic background and significance of studying cavitation damage to gear pump are expounded,the mechanism of cavitation of gear pump is briefly described,and the research status of cavitation damage of pump components at h ome and abroad is summarized.The basic concepts and theoretical basis of gas-liquid two-phase flow are summarized;the commonly used cavitation models and research methods in multi-phase flow are briefly introduced;the description methods of gas-liquid two-phase flow involved in cavitation damage research are elaborated;and Pumplinx pump simulation software is selected to be suitable for the solution object used in this paper.By comparing various research methods in multiphase flow problems,the cavitation research method of the full cavitation model used in this paper is finally determined.The flow field model of gear pump is established,and the observation points are established in the model.The selection of monitoring points is selected in the pressure change region of the flow field in the gear pump.The model considers that the temperature change of hydraulic oil leads to the change of oil viscosity,and then influences the pressure,oil flow velocity,gas content and density.The simulation monitors the inlet and outlet of the pump and the meshing area of the gear,analyses the change of the relevant parameters caused by the temperature change,monitors the pressure,gas content and the energy level of the cavitation damage in the cavitation area,and summarizes the regularity of the change of the cavitation damage caused by the temperature change.The cavitation of gear pump under the condition of variable speed is studied.The influence of gear pump speed on pressure,oil flow velocity,gas conte nt and density is considered in the study.The pressure,gas content and cavitation damage level in the cavitation area under different speed conditions are monitored.The regularity of cavitation damage caused by the change of gear pump speed is summarize d.According to the theory of cavitation induced noise and vibration,the characteristics of noise and vibration are the important criteria for judging cavitation of gear pump.In view of the cavitation phenomenon studied in this paper,the noise and vibration of the existing gear pump are measured.According to the relevant national standards,the noise and vibration of the existing gear pump are measured and preliminarily analyzed.Finally,the rationality of the simulation results is verified.