GB692188A - Improvements in or relating to compressors - Google Patents

Abstract

692,188. Axial-How compressors. STALKER, E. A. June 9, 1949 [June 21, 1948], No. 15388/49. Class 110(i) An axial-flow compressor comprises rotor passages each having an exit larger in cross-sectional area and radial depth than the inlet to the passage. In a multi-stage compressor each rotor passage 19, Figs. 1 and 2, expands downstream with increasing radial height, the divergence being given to both the inner wall 23 and the outer wall 25, as shown, or to the outer wall only. Successive passages 19 may decrease in axial length, as shown. The rotor blades 21 are straight and parallel. The stator passages 29 expand over the substantially straight portions from B to C and then contract over the curved portions from C to D so as to provide an acceleration which avoids separation of the boundary layer. at the convex side of the stator blades 27. Alternatively, each stator passage may decrease in radial height from inlet to exit. The ratio of hub diameter to, tip diameter is preferably not less than 0.85 but may be made smaller, say 0.7, by curving at least a part of each rotor blade. The trailing edges of the rotor blades may be twisted so that less whirl velocity is imparted at the tip than at the root. The trailing edges of the stator blades may be twisted to permit the rotors to perform equal work at the root and tip. To reduce the overall diameter, the rotor diffusion may be less in the earlier stages than in the later stages, e.g., the ratio of exit area to inlet area may be 1.25 for the first rotor, increasing progressively to 3 for the last rotor. The blades may have faired leading portions, as shown in Fig. 5.