Hydraulic machinery inevitably encounters cavitation problems during operation.The hazards of the cavitation process are mainly reflected in three aspects: First,cavitation will lead to serious deterioration of hydraulic performance of hydraulic machinery;second,bubbles can cause damage to the surface of the material known as cavitation.At the same time,accompanied by cavitation damage,there are also problems such as vibration and noise;third,cavitation will affect the flow’s unsteady characteristics or dynamic response characteristics.Changes to the dynamic response characteristics can make the flow unstable,and the instability caused by cavitation includes rotational cavitation and cavitation surge.These instabilities can lead to large oscillations in global flow and pressure,resulting in unsteady rotor dynamics and consequently,structural failure of the hydraulic system.At present,the research on unsteady flow instability in hydraulic machinery is in its infancy.The research on flow instability caused by cavitation is a hot and difficult issue in the field of hydraulic machinery.It is almost impossible to completely eliminate the harm caused by cavitation flow instability in the engineering field.Therefore,the research direction of cavitation hazards has been adjusted to reduce and suppress the negative effects of cavitation instability,that is,the control of cavitation.Momentarily,there are measures such as adjusting the pipeline layout,installing asymmetric interference plates,installing circumferential grooves,and air supply for hydro-mechanical cavitation suppression.These methods have a certain inhibitory effect on specific cavitation instability,but the cavitation instability is not completely inhibited,and the mechanism of inhibition is not fully understood.Therefore,exploring and discovering cavitation instability control theory and technology with practical engineering value is significant for improving the anti-cavitation characteristics,and hydro machines green and intelligent operation.The research studies cavitation flow instability in a centrifugal pump based on experiments and numerical simulations.An active control method for cavitation is proposed in which obstacles are arranged on the blade’s working face.The influence of obstacles on centrifugal pump’s steady cavitation characteristics is systematically studied.Through the research of the inverse problem of the obstacle control method,the dimensionless geometric parameters of the obstacle with the best restraining impact on cavitation instability in centrifugal pump are obtained.Main contents and research innovations of research study is given.The research status of cavitation flow instability and control is summarized,cavitation and other phenomena conditions and features.Also,based on the centrifugal pump closed experimental platform,the hydraulic operation,cavitation and pressure pulsation of the centrifugal pump were tested.A high-precision test was performed to study response characteristics of cavitation flow in a centrifugal pump,including external characteristic curve and cavitation characteristic curve.Taking research object as a centrifugal pump with a low specific rotation speed,combined with the k-ω SST turbulence model corrected by viscosities at high Reynolds number and the Zwart Gerber Belamri cavitation model,a three-dimensional unsteady full flow channel numerical simulation was carried out,and the fluid machinery in Gansu Province,Lanzhou University of Technology was studied.The hydraulic performance test experiment was done by centrifugal pump’s closed experimental bench at key laboratory,and the experimental data verified how accurate the computational results were.Intrinsic instability of cavitation flow in centrifugal pump is studied.The computational results represents cavitation shedding on the back of impeller in the centrifugal pump is not dominated by the re-entrant jet,and size of the re-entrant jet is not of same order of magnitude as the main flow in the channel’s flow.The monitoring attack angle of the impeller blade inlet flow shows that the inlet flow on the back of the blade in the centrifugal pump is a separation flow dominated by the reverse pressure gradient,and the reverse jet does not contribute to the cavitation shedding.At the same time,the causes of the asymmetric cavitation in the impeller channel of the asymmetric pressurized water chamber are analyzed.Add obstacles to the low specific speed centrifugal pump blade working surface to control cavitation.Experiments and numerical simulations analyses the effect of obstacles on the cavitation shape flow field structure and turbulent flow characteristics.The results show that when cavitation does not occur,the wake vortex induced by obstacles will increase the energy loss in the centrifugal pump,resulting in a small drop in efficiency.When cavitation occurs,the obstacles can effectively optimize the flow field structure,weaken the vortex strength in the flow channel near the back of the blade,and significantly reduce the growth rate of the cavitation volume in the flow channel,first derivative of the cavitation volume.The main mechanism of the obstacle to achieving the control effect is to optimize the flow field structure,change the flow transition characteristics of the flow in the impeller channel,and induce high-pressure waves to rupture the cavities.The inverse problem of cavitation control with obstacles inside a centrifugal pump has been studied to obtain dimensionless geometric parameters with better suppression effect,such as the crosssectional shape is circular,the height of the obstacle is 1/2 of the width of the impeller outlet,and the position of the obstacle is located in the impeller,at the center of the axial streamline at 45% of the radius.