Flow control arrangement

Abstract

A flow control arrangement ( 30; 50; 70 ) is described in which an inlet slot 35, 55, 85 is positioned prior to a stationary structure ( 33; 43; 53; 73; 83 ) such as a stator or pylon in order that air flow is bled or removed from a main flow 31, 51, 81 . The removed air passes through a passage duct 36, 56 and is re-injected through an outlet nozzle 37, 57, 87 with an askew angle consistent with rotor blades 32, 52, 72, 82 of a turbine. In such circumstances, distortion in the flow due to the stationary structure 33, 43, 53, 83 is relieved such that there is less instability downstream from that structure 33, 43, 53, 83.

1 . A flow control arrangement for turbine engines, the arrangement comprising a turbine to force fluid flow directed towards a stationary structure through a conduit whereby that fluid flow is susceptible to distortion instability downstream from the stationary structure, the arrangement characterised in that a slot in the conduit prior to the stationary structure is provided in order to remove in use fluid from that fluid flow and an outlet provided prior to the turbine through which the removed fluid is released.  
     
     
         2 . An arrangement as claimed in  claim 1  wherein the slot is substantially aligned with the stationary structure.  
     
     
         3 . An arrangement as claimed in  claim 1  wherein the fluid is air.  
     
     
         4 . An arrangement as claimed in  claim 1  wherein the outlet is aligned with the stationary structure with a pre-determined angular offset.  
     
     
         5 . An arrangement as claimed in  claim 1  wherein the stationary structure is a pylon or guide vane or drooped inlet or non-axisymmetric intake.  
     
     
         6 . An arrangement as claimed in  claim 1  wherein the outlet has a trenched end.  
     
     
         7 . An arrangement as claimed in  claim 1  wherein the slot presented width to the stationary structure is determined for flow removal in order to provide flow stability downstream of that stationary structure.  
     
     
         8 . An arrangement as claimed in  claim 1  wherein the position of the slot relative to the structure is chosen to provide flow stabilisation.  
     
     
         9 . An arrangement as claimed in  claim 1  wherein removed fluid passes along a passage from the slot to the outlet.  
     
     
         10 . An arrangement as claimed in  claim 9  wherein the removed fluid utilises the pressure of the rotor outlet in order to drive removed fluid movement along the passage.  
     
     
         11 . An arrangement as claimed in  claim 1  wherein the slot includes diffuser vanes.  
     
     
         12 . An arrangement as claimed in  claim 11  wherein the diffuser vanes de-swirl the removed fluid flow to facilitate movement through the passage.  
     
     
         13 . An arrangement as claimed in  claim 1  wherein the outlet includes guide vanes to guide removed fluid release toward the turbine.  
     
     
         14 . An arrangement as claimed in  claim 13  wherein the guide vanes direct released flow for consistency with blades of the rotor and in particular the angle of those blades.  
     
     
         15 . An arrangement as claimed in  claim 9  wherein the passage is shaped to facilitate at least one of: removal of fluid flow by the slot; and presentation of the removed fluid to the outlet for appropriate release prior to the turbine.  
     
     
         16 . An arrangement as claimed in  claim 15  wherein the passage narrows or constricts from the slot to the outlet.  
     
     
         17 . A turbine engine incorporating an arrangement as claimed in  claim 1.