Study On Flow Characteristics Of High Speed Centrifugal Pump Based On Solid-liquid Two-phase Flow

High speed centrifugal pump has the advantages of small flow,high head and no need for multipolarization,so it is widely used in high-rise building fire,chemical,aerospace and water conservancy and other fields.Due to the reasons of water quality in the process of conveying pump often accompanied by sediment and other solid particles,when the high-speed pump solid-liquid two phase medium,because of the liquid phase and solid phase interaction,mutual influence of two kinds of medium,make the mechanical internal flow is extremely complex,flow components wear and vibration seriously affects the performance of the pump and longevity.Based on a specific speed 67 high-speed pump,based on the Mixture multiphase flow model,analyzed the different flow rate,particle size and different speed,different particle volume fraction,the influence factors such as speed of impeller with solid phase volume fraction,streamline distribution,and in the impeller passage,key location Settings such as isolation,the volute tongue export monitoring to analyze its performance under different impact factors of influence,the change law of pressure pulsation and radial force of high-speed pump under the solid liquid two phase operation to provide some practical reference value.The main research results are as follows:(1)When the volume fraction of impeller inlet particles is the same,the optimal efficiency point shifts to the low-flow condition at low rotating speed,and to the large-flow condition at high rotating speed;The overall pressure distribution in the impeller is increasing from the impeller inlet to the impeller outlet,and the impeller inlet,the leading edge and the back of the blade are the most serious parts of wear and damage.(2)The high-speed pump runs under different particle diameters,and the main position of the vortex is in the impeller passage,while only part of the vortex appears at the outlet of the volute.Under the condition of the same particle volume fraction,the velocity streamline distribution is more uniform and stable at the condition of large flow rate and high speed,and the uniformity of the streamline increases with the increase of inlet flow rate.When the impeller inlet flow is the same,the particle volume fraction of 0.65% is the critical value for the high speed pump to operate efficiently in solid-liquid two-phase.(3)The critical value of the pressure fluctuation speed at the monitoring point of the impeller passage is near the particle volume fraction of 0.65%;The main frequency of pressure pulsation at each monitoring point occurs at blade frequency and low frequency multiplier.Under different particle size conditions,D=0.1mm is the boundary value of the increase and decrease speed of pressure pulsation at the monitoring point.The tongue is the main cause of pressure pulsation.At the same particle volume fraction under the same working condition,the pressure pulsation value of each monitoring point increases continuously with the increase of rotational speed.(4)When the inlet flow is 0.8Qd and the particle volume fraction is 0.65%,the radial force on the impeller of the high-speed centrifugal pump is small;The diameter of the solid particle is 0.1mm,which is the boundary value of the increase and decrease speed of the impeller’s radial force.Under the conditions of different particle volume fraction and impeller speed,the radial force on the impeller is the least when the particle volume fraction is 0.65%and the rotational speed is n=11000r/min.