Rolls-Royce Corporation

Ivor J Day

Christopher Freeman

Thomas Scarinci

William B Wright

With highly loaded rotors and stators problems can occur with secondary flows sweeping low momentum fluid across the blades reducing efficiency. By provision of collector slots to collect the secondary air and direct that air to a return slot in a rotor hub it is possible to provide impetus to the collected secondary flow to an outlet slot such that there is dispersal of the secondary flow and therefore reduce the effects upon the overall performance of a gas turbine engine incorporating the arrangement.

Rotor arrangement

A three-stage lean burn combustion chamber () comprises a primary combustion zone (), a secondary combustion zone () and a tertiary combustion zone (). Each of the combustion zones () is supplied with premixed fuel and air by respective fuel and air mixing ducts (). The fuel and air mixing ducts () have a plurality of air injection slots () spaced apart transversely to the direction of flow through the fuel and air mixing ducts (). The air injection slots () extend in the direction of flow through the fuel and air mixing ducts () to the reduce the magnitude of the fluctuations in the fuel to air ratio of the fuel and air mixture supplied into the at least one combustion zone (). This reduces the generation of harmful vibrations in the combustion chamber ().

Combustion chamber

A three-stage lean burn combustion chamber ( ) comprises a primary combustion zone ( ), a secondary combustion zone ( ) and a tertiary combustion zone ( ). Each of the combustion zones ( ) is supplied with premixed fuel and air by respective fuel and air mixing ducts ( ). The fuel and air mixing ducts ( ) have a plurality of air injection slots ( ) spaced apart transversely to the direction of flow through the fuel and air mixing ducts ( ). The air injection slots ( ) extend in the direction of flow through the fuel and air mixing ducts ( ) to the reduce the magnitude of the fluctuations in the fuel to air ratio of the fuel and air mixture supplied into the at least one combustion zone ( ). This reduces the generation of harmful vibrations in the combustion chamber ( ).

A three-stage lean burn combustion chamber ( ) comprises a primary combustion zone ( ), a secondary combustion zone ( ) and a tertiary combustion zone ( ). Each of the combustion zones ( ) is supplied with premixed fuel and air by respective fuel and air mixing ducts ( ). The fuel and air mixing ducts ( ) have a plurality of air injections apertures ( ) spaced apart in the direction of flow through the fuel and air mixing ducts ( ). The apertures ( ) reduce the magnitude of the fluctuations in the fuel to air ratio of the fuel and air mixture supplied into the at least one combustion zone ( ). This reduces the generation of harmful vibrations in the combustion chamber ( ).

Flow control method and means

The invention provides a method of controlling gas flow in an axial flow compressor, in which the flow at least at one chosen station in the direction of flow through the compressor is sensed at a series of circumferentially spaced positions. Flow variations above a predetermined limit are evaluated to give an actuating response if the variations indicate a disturbance above a predetermined acceptable level is present. When such a disturbance is detected, high pressure flow bled from the exit end of the compressor is injected at said station to supplement the main gas flow there. An incipient rotating stall cell will appear as a variation occurring sequentially at the circumferentially spaced positions. By responding to such a condition with a pressure injection flow, it is found possible to suppress both rotating stall and surge conditions in the compressor before the disturbance develops fully.

To control unsteady motion phenomena in turbomachines, it has been proposed to employ an active control system to modify the flow conditions. In the present invention, the modification is effected by devices mounted in a bullet or nose bullet at the entry to a rotor of the turbomachine.

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Cambridge, United Kingdom

Ivor J Day