Active vaned passage casing treatment
AssigneeUnited Technologies Corporation
InventorDavid E. Hobbs
Life of this patent
Estimating the term…
Abstract
The recirculating flow in the vaned passage in the case surrounding the tips of the fan blades of a turbo fan engine or ducted fan propulsor is modified or blocked off during certain engine or aircraft operating modes. In one embodiment an aneroid valve closes off the vaned passage upon attaining a given altitude and fails open to assure that the safe stall margin is retained during take off. The active VPCT serves to increase fan efficiency and engine thrust while maintaining stall margin at the required safety level. The vaned passage in another embodiment is utilized to abate or preclude the stall precursor waves manifested by the rotor blade by modulating the recirculating flow as a function of time.
Claims18
An active vaned passage casing treatment for a rotor supported for rotary motion, a plurality of circumferentially spaced blades supported in said rotor for rotation for flowing air therethrough, each of said blades having a tip a casing surrounding said blades, a passage in said casing adjacent said tip having an inlet and an outlet and flow straightening means disposed therebetween to remove air through said inlet adjacent said tip of each of said blades and return said air through said outlet adjacent said tip, means for rendering said passage inoperative to prevent the flow of air therein at predetermined operations of said rotor when it is rotating.
An active vaned passage casing treatment in combination with a gas turbine engine including a rotor supported for rotary motion, a plurality of circumferentially spaced blades each having a tip supported in said rotor for rotation for flowing air therethrough, a casing surrounding said blades adjacent said tip, a passage in said casing adjacent said tip having an inlet and an outlet and flow straightening means disposed therebetween to remove air through said inlet adjacent said tip of each of said blades and return said air through said outlet adjacent said tip, means for rendering said passage inoperative to prevent the flow of air therein at predetermined operations of said rotor when it is rotating.
An active vaned passage casing treatment for a rotor supported for rotary motion, a plurality of circumferentially spaced blades supported in said rotor for rotation for flowing air therethrough and being subjected to stall precursor static pressure waves, a casing surrounding said blades, each of said blades having a tip, a passage in said casing adjacent said tip having an inlet and an outlet and flow straightening means disposed therebetween to remove air through said inlet adjacent said tip of each of said blades and return said air through said outlet adjacent said tip, means for canceling the stall precursor static pressure waves by controlling the flow of air in said passage and control means responsive to a function of time to control said means for canceling the stall precursor static pressure waves to modulate the flow in said passage.
Dependencies are inferred from the claim text.