大断面矩形有压短管进口段优化壁面拟合依据

Coinciding Basis for the Optimum Walls of the Inlet of A Large Cross-Section Rectangular Pressuring Conduit

Considering some problems presently existing in the design of pressure rectangular conduit, this paper discusses about the optimum basis that the walls of the inlet section of a large cross-section rectangular pressuring conduit coincide the nappe of the relative sharp-edged rectangular orifice.If us- ing the deciding method based on spillwav curve to have design walls slightly insert into the relative nappe outline of jet flowing form a sharp-edged orifice,the optimum design should decide the inserting degree to ensure that the designed conduit has the maximum discharge coefficient under the given head and,at the same time,should be free from negative pressure.Therefore,the concepts that the conduit walls are inserted in the nappe contour flowing from the relative sharp-edged rectangular orifice ac- cording to the relationships of their active cross-section areas and between the diffusing shides of the nappe and the sides of the rectangular conduit are introduced.The formulas of inserting degree pa- rameters and the formula for finding optimum coinciding cross-section are established finally.