JPS6344960B

PURPOSE:To give no excessive prewhirl and obtain a uniform flow in a small suction passage by protruding a part of the suction passage wall into the suction passage so as to change the resistance to the fluid. CONSTITUTION:Side walls 8a, 8b protruding to a suction passage 2 side are provided near the impeller 3 eye section of the impeller side wall face of a suction casing 1, and the side wall adjusts the suction passage width directly before the impeller 3. The height of the wall side is made maximum at the baffle 7 back nearest to a suction port, and the height is gradually decreased toward the flow direction and is made minimum at the widning end of the suction passage 2. Thereby, the wall face 8a acts as the resistance against the flow so as to interrupt the inflow in the vicinity of cross sections F, A where the suction port is nearest and the flow is easy to pass through, and the resistance is reduced to facilitate the inflow at the across sections D, E near the widning end of the suction passage 2, thus no excessive prewhirl is given and the flow directly before the impeller 1 can be kept uniform.