GB1102091A - Improvements relating to machines of the cross-flow type for inducing flow of fluid - Google Patents

Abstract

1,102,091. Transverse-flow blowers and pumps. FIRTH CLEVELAND Ltd. Feb.3, 1965 [Feb. 5, 1964], No.4975/64. Heading F1C. A transverse-flow machine for inducing a flow of liquid or gaseous fluid comprises a guide body subtending less than 40‹ at the rotor axis and adjacent which a main vortex forms, and a guide wall extending around the rotor on the side thereof opposite the guide body and defining therewith an outlet from the rotor, the guide wall continuing on the inlet side beyond a region of nearest approach to the rotor to an abrupt termination and forming with the rotor between the region and the termination, a pocket into which a second vortex extends, both vortices interpenetrating the path of the rotor blades in normal operation, and the termination and the guide body defining an inlet and subtending more than about 90‹ at the rotor axis. The blower shown in Fig. 2 comprises a wall 4 having a straight lead-in wall portion 8 which is approximately tangential to the inner envelope 9 of the rotor blades 2 and meets at a rounded nose 7 a guide body including a concave main guide portion 6. The nose 7 has a radius equal to about half the radial depth of the blades 2 and at its closest approach to the rotor is spaced from it by some two thirds of this depth. An angle of some 90‹ is subtended between the main guide portion 6 and an outlet wall portion 10. A guide wall 5 comprises a main guide portion 11 which diverges steadily from the rotor in the direction of rotor rotation and merges into an outlet wall portion 13 which defines with the portion 10 a diverging outlet duct 14. The line 12 of nearest approach of the main guide portion 11 to the rotor is about opposite the nose 7 and is spaced from the rotor by a distance about equal to the radial blade depth. An approximately radial portion 17 of the wall 5 joins the wall portion 11 to a wall portion 16 approximately concentric with the rotor and spaced from it by some three times the radial blade depth (i.e. about one third of the rotor diameter. The portions 16, 17 define a pocket 15 which is open to the inlet I and subtends some 90 degrees at the rotor axis. During normal operation, a main vortex A forms with its core adjacent the main guide portion 6 and its centre within the blades 2, and a second vortex B forms with its core partly within the pocket 15. Both vortices interpenetrate the path of the blades 2. On throttling, as by means of pivoting outlet louvres (T), Fig. 3 (not shown), vortex B expands, entraining more of the lower speed flow and permitting only high velocity flow to reach the outlet duct 14. In a modification, Fig. 1 (not shown), an auxiliary guide body (19) is located in the space between the main guide portion (6) and the rotor to define with the rotor a converging gap and to define with the guide portion (6) a channel leading from the entry of the outlet duct (14) back to the rotor adjacent the nose (7). A flap may be provided in the latter channel to control the vortex (A). In further modifications, Figs.5 and 6 (not shown), the radial wall portion 17 is omitted. In Fig. 5, the main guide portion (6) is made more concave and the space between it and the rotor is provided with a vane (100) to control the vortex A. In Fig. 6, the main guide portion 6 is replaced by a rounded nose (103). The blades 2 may be skewed instead of being parallel to the rotor axis.