Study On Cavitation Performance Of New Channel Type Sewage Pump

New channel type sewage pump was designed by some pump enterprise to meet market demand,which adopt a new kind of impeller structure,so its hydraulic and cavitation performance are unknown.Main work and achievements of this paper are as follows:1.Cavitation tank,pump section,piping system and other test required components are designed based on existing impeller and volute's structure and size,electric motor,torque meter,vacuum pump,flowmeter,pressure sensor and other instruments are selected and purchased,finally,a closed cavitation test bench of new channel type sewage pump which meet national standards was built.2.Pump's property test was conducted on the built closed cavitation bench,and bench's reliability was verified by repeated test,pump's maximum efficiency point parameter meet the design requirements,which is Q=260m3/h,H=5.5m,P=5.8Kw,?=70.9%.The cavitation test was completed by vacuum extraction methods to reduce the pump inlet pressure,H-NPSHacurves of each flow and pump's cavitation performance curve were drew,the critical NPSH of rated flow is 8.41 m.3.External characteristic numerical calculation and cavitation performance simulation of new channel type sewage pump were conducted,the calculation results is consistent with test results,three low-pressure area of impeller surface were found by analyzing the pressure contour,joint between working face of blade inlet and front cover,middle back face of blade inlet and near the back face of blade outlet respectively.The vapor distribution of impeller surface verified the validity of pressure contour.4.Pressure fluctuation signal of different cavitation degree was collected by setting up four monitoring points.It can be found that with the continuous decrease of NPSH,the amplitude of rotating frequency show an increasing trend overall,but there exists a falling inflection point at critical NPSH,and the increasing rate of amplitude at outlet is highest,which reflect diagnosing cavitation of new channel type sewage pump by monitoring amplitude increasing rate at outlet's rotating frequency is more reliable.When this value run up to 50.79%,it can be concluded that new channel sewage pump produces cavitation.