Investigation On 3-D Design And Development Of Hydraulic Model Of Double Channel Sewage Pump Impeller

Research was carried out focusing on Three-Dimensional design methods of Double Channel Sewage Pump' s impeller and developing programs based on redevelopment of Pro/E for parametric design of impeller and CFD computation of impeller and volute,the whole flow passage of Double Channel Sewage Pump.Some achievements as follows were obtained.Some problems of usual drawing manner of the Vane of Double Channel Impeller were found.It is the inconformity between the dimensions of plane-view and pinacoid-view of fluid cross-section.The shape of cross-section is an ellipse folded in half through one symmetry axis.And the axis keeps perpendicular with pinacoid-view.Thus the direction of the cross-section is unrelated with center channel curve in plane-view.Traditionally,it is assumed that the cross-section is perpendicular with center-channel curve.This is not the fact.It is considered the major cause resulted in the disagreement among plane view,dimension of cross-section and actual wood former of double channel impeller.The more reasonable design process suggested is drawing design first,then three-dimension design second,and three-dimension achieved finally can be use to create the drawing so as to secure the agreement of the three.Design experience proves the rationality of the design process.The impeller of Double Channel Sewage pump is deferent from common centrifugal pump,its shape is special.So the method of building 3-D model still needs to be explored further.Research of modeling 3-D shape of the impeller in Pro/E was carried out.3-D passage center-line is generated by projection,and then it is made the original trajectory to produce inner passage by command sweep and blend,with passage cross-sections as sections. Inner passage center-line is extended to the outer diameter of the impeller with its rule formula,the curve resulted is regarded as an original trajectory,and sections is placed in proper position through outer passage profile line.Then the outer passage can be made by command sweep and blend. A failure to form Double-Inner-Channel most possibly is encountered during the procedure to transform 2-D drawing to 3-D model of Double-Channel impeller,and analysis was available for the potential causes,the measures was presented to improve such condition.By practice,the method presented proves correct and efficient.Problem of disagreement between 2-D drawing and actual wood former of Double-Channel impeller of sewage pump most possibly encountered if the design is from traditional 2-D manner.Research was carried out for the method of 3-D design directly in Pro/ENGINEER,so 2-D drawing can be produced by projecting through 3-D impeller designed.The procedure can secure the agreement between 2-D drawing and actual wood former. Additionally,a formula was deuced,which shows the relation between the outlet angle of center line of channel and wrap angle,variant coefficient, if Archimedes spiral is assumed as the curve of center line of plate plane. It is the basis for controlling outlet angle of channel.Another formula was present for the calculation of normal distance from points on the center line to outer diameter and formula of cross-section area is also available.They provide convenience for CAD of Double-Channel impeller.Based on it,a analytic method was developed for finding out the outlet point.Based on the three-dimension design method,program for parametric design of the impeller of Double-Channel Sewage Pump was developed.It was redeveloped in Pro/E with VC++.The program can be use to create passages of the impeller of Double-Channel Sewage Pump directly by inputting some required parameters.Resulted passages of impeller can be a proper base for further CFD computation and NC manufacture.It provides chance to preview the axial profile and plane profile,so user can decide proper plan at first after inputting parameters.Before the outer passage is created, user can check inner passages is successful or not,then decide whether to do something to make them better.The program also provide modules to modify the control curve of inner passage flow area and regulation of outer passage thickness,in order to control the shape of the impeller.And Double Channel Impeller QW950-15-55 was designed by the programme.The internal flow in impeller and volute casing of QW950-15-55 double-channel passage pump was investigated.Based on the Reynolds averaging N-S Equations and standardκ-εtwo equation turbulent model, the simulations of turbulent flow between impellers are performed by using the flow computing software Fluent under 11 differentoperating conditions. Important flow information was obtained.Model machine was manufactured by Shandong Shuanglun Pumps Co.,Ltd,and Characteristics experiment was carried out and the efficiency of design condition reach 85.33%.However,the efficency of current domestic sewage pumps of all types impeller,with outer discharge diameter 300mm,is between 74%～83%.The experiment results comparing with CFD predicted characteristics shows a good identity.So CFD results can provide references for further design.