GB920188A - Improvements in or relating to centrifugal fans and compressors - Google Patents

Abstract

920,188. Centrifugal fans and compressors. SOC. ANON. DES ETABLISSEMENTS NEU. Nov. 1, 1960 [Jan. 21, 1960], No. 37543/60. Class 110(1). In the two-stage fan or compressor shown in Fig. 1, air enters the first-stage impeller 5 via an inlet casing 32 and, after leaving the first-stage volute 34, passes by way of a duct 53, right-angle bends 54, 56 and a 45 degree bend 58, Figs. 1 and 3, to the inlet casing 33 of the second stage. The air is discharged from the second-stage volute 35 through an outlet 40. Both impellers are as described in Specification 733,533, with blades passages which are constant or decrease slightly in cross-sectional area, the impeller shrouds being radially extended beyond the blades and flared at 23, 24 to form a rotary diffuser. The blades are of aerofoil form or have a cylindrical inlet part followed by a radial or nearly radial part, as described in Specification 733,533. The volutes 34, 35 provide lateral spaces 43, 44, each having a width between one and two times the outlet width of the associated rotary diffuser. The radius of curvature of each surface 46 is about one-tenth the radius of the associated rotary diffuser. The duct 53 is convergent as viewed in Fig. 1, but is divergent as viewed in a plane perpendicular to the axis of the machine to permit the cross-sectional area to remain constant. The bends 54, 56 are also of constant cross-sectional area, while the cross-sectional area of the bend 58 increases slightly. Flow disturbance at entry to each impeller is prevented by curved walls 51.