GB867849A - Improvements in or relating to axial flow compressors, and their applications - Google Patents

Abstract

867,849. Axial-flow compressors; gas turbine plant. SZYDLOWSKI, J. March 20, 1958 [April 4, 1957], No. 8979/58. Classes 110 (1) and 110 (3). A rotational velocity is imparted to the inlet axial fluid stream of an axial-flow compressor upstream of the impeller blades by injecting an auxiliary fluid into the stream through a number of oblique or radial orifices, the direction and shape of which are respectively so determined that the auxiliary fluid penetrates into the stream and produces tangential deviations of the stream around its axis. In the axial-flow compressor shown in Fig. 1, air is bled from the discharge through holes 5 into.an annular manifold 6 and conveyed through ducts 7 to a further annular manifold 8, from which it is returned to the intake through nozzles 9. The nozzles 9 are inclined to the radial direction to impart whirl to the returned air. The returned air mixes with the main stream of air in the intake and imparts pre-whirl to it. The flow of the returned air is controlled by a valve 10 in each duct 7, the valves being connected by bevel gearing to a common control member 13; the control may be automatic, in accordance with the pressure, output, temperature or speed of the compressor. Additional nozzles 16, inclined oppositely to the nozzles 9 and fed from the manifold 6 through ducts 14 and a manifold 15, may be provided, control valves similar to the valves 10 being provided in the ducts 14. Instead of being provided in the outer wall of the intake, the nozzles may be provided in a stationary central fairing in the intake. Fig. 6 shows an axial-flow compressor in which air is bled from an intermediate stage through holes 36 into an annular manifold 37 and returned to the intake through nozzles 39 which have the shape of a guide-blade cross-section, the returned streams of air acting as virtual guide-blades to impart pre-whirl to the main air stream. The nozzles 39 may be inclined to the radial direction to impart whirl velocity to the returned air. Where the compressor forms part of a jetpropulsion engine, the returned air, being heated by the compression it has undergone, acts as a de-icing agent. Additionally, a deicing fluid may be injected. Instead of being bled from the compressor, the auxiliary air may be derived from a different source, and a fluid other than air may be used.