Study On Performance Optimization And Internal Flow Characteristics Of The Side Channel Pump With Convex Blade

The side channel pump is an ultra-low specific speed radial vane pump,which has the capability to self-prime and develops high pressure heads at comparatively low specific speeds.Due to its unique flow advantages,it has found its applications in many fields,especially in the transportation of low-viscous and clean fluids at high head with small flows and two-phase flow delivery under extreme conditions.Compared to other vaned hydraulic pumps,the efficiency of the side channel pump is low due to the large numbers of vortices impeding the flow operation of side channel pumps.Therefore,this thesis proposes a novel optimization design method by introducing a convex blade.Through the combination of numerical simulations and experiments,the energy conversion characteristics and internal flow physics of the side channel pump with convex blades are deeply studied.This thesis provides a relevant basis for widening the application range of side channel pumps and supplementing the unsteady flow theory.The main findings of the present thesis are as follows:?1?The hydraulic performance and internal flow physics of the side channel pump with a convex blade are analyzed by numerical simulations,and the position of the convex blade is further investigated.The research proposes that the addition of the convex blade can widen the high-efficiency zone of side channel pumps,and the performance improvement is highest when the convex blade is close to the inner radius of the impeller.From the internal flow field,when the convex blade is close to the inner radius,the fluid path line is more stable and the turbulent energy dissipation is relatively small.Furthermore,the lengthways vortex is characterized by a relatively high velocity between the impeller and the side channel.This significantly strengthens the momentum exchange between the impeller and side channel.?2?Using the Q,?₂ and?vortex identification methods,it was found that the vortex structures captured by the?method was more accurate and reasonable than the traditional methods.The results show that the vortices in the side channel pump with a convex blade are mainly distributed in the impeller and the side channel,especially near the inlet and outlet areas.The distribution of vortex in the impeller changes periodically with a variation in the blade number.Due to the changes in fluid flow conditions,the vortices at the inner radius of the impeller are mostly dominated on the pressure side.On the other hand,the vortices on the outer radius are mostly on found on the suction side.In the side channel,distribution of vortex has no obvious change with impeller rotation.Additionally,there are a large number of axial vortices at the inner and outer radiuses of the impeller and near the inlet area of the pump.These axial vortices impede the lengthways vortices and cause flow losses.?3?It is found that the intensity of pressure fluctuations at the inlet and outlet is significantly higher than that in other areas due to the change of the fluid flow pattern at these areas.The pressure of the monitoring points in the impeller and side channel fluctuate many times in one revolution,and the number of fluctuations is related to the number of flow exchange movements between the impeller and side channel.The monitoring points produce two peaks of maximum values of fluctuating pressure near the inlet and outlet areas respectively in a fluctuation period.Meanwhile,the pressure fluctuation peaks of all monitoring points appear at the blade frequency and its multiples.The peak values gradually decrease as the frequency increases.Moreover,it is found that the position of the convex blade has minimal effect on the frequency characteristics of the pressure pulsation intensity of side channel pumps.?4?A hydraulic performance test bench is established for the side channel pump to ensure the accuracy and reliability of the numerical simulation results.It is found that the numerical simulation calculation results are consistent with the overall trends of the experimental test results,and the error of each operating point is within 3%.This proves that the numerical simulation methods and results in this paper are accurate and reliable.