Method and system for controlling the clearance at the blades tips of a turbine rotor
a turbine rotor and blade tip technology, applied in the direction of machines/engines, liquid fuel engines, transportation and packaging, etc., can solve the problems of limiting the thermal expansion of the engine, performance loss, and the disadvantage of restraining the cooling air stream by complex and bulky valves
Inactive Publication Date: 2013-07-11
SN DETUDE & DE CONSTR DE MOTEURS DAVIATION S N E C M A
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Benefits of technology
The present invention proposes an active control solution for gas turbine engines that is minimalist in terms of mass and cost. It uses a single air tap at the compressor to guarantee a sufficient pressure differential for delivering cool air to the turbine shroud. The air tapped at the compressor is delivered only into the control housing and does not supply any other components of the engine. This reduces the amount of air ducts and air taps in the engine and simplifies the structure and control of the valve, resulting in a low cost control system with low mass.
Problems solved by technology
The cool air delivered to the outer surface of the turbine shroud has the effect of cooling the latter and thus limiting its thermal expansion.
Such a system, however, exhibits numerous disadvantages such as its considerable use of space inside the nacelle of the turbine engine, the strong dependency of its effectiveness on aerothermal conditions existing within the nacelle and performance losses connected with the tapping of air flow from the fan which does not participate in providing thrust.
Though effective, such a system exhibits the disadvantage of resorting to a complex and bulky valve to modulate the cooling air stream.
In particular, in the case of an application to a small sized turbine engine, the use of such a valve is not optimal in terms of mass and cost.
Method used
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Embodiment Construction
[0022]FIG. 1 shows schematically a turbojet 10 of the bypass, twin spool type to which the invention particularly applies. Of course, the invention is not limited to this particular type of gas turbine aero-engine.
[0023]In well-known fashion, the turbojet 10 with longitudinal axis X-X includes in particular a fan 12 which delivers a stream of air into a primary flow passage 14 and into a secondary flow passage 16 coaxial with the primary flow passage. From upstream to downstream in the direction of flow of the gas stream passing through it, the primary flow passage 14 includes a low-pressure compressor 18, a high-pressure compressor 20, a combustion chamber 22, a high-pressure turbine 24 and a low-pressure turbine 26.
[0024]As shown more precisely by FIG. 2, the high-pressure turbine 24 of the turbojet includes a rotor consisting of a disk 28 on which is mounted a plurality of moving blades 30 positioned in the passage of the primary flow 14. The rotor is surrounded by a turbine casi...
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A system and method for controlling clearance between tips of moving blades of an aeroplane gas-turbine engine and a turbine shroud of an outer casing surrounding the blades. The method includes controlling, according to an operating speed of the engine, a valve positioned in an air duct opening at a stage of the compressor of the engine and leading into a control housing positioned around the outer surface of the turbine shroud and supplied with air coming only from the compressor stage. The valve is opened to cool the turbine shroud during a high-speed phase corresponding to takeoff and climb phases of an aeroplane propelled by the engine and during a nominal-speed phase following the high-speed phase and corresponding to a cruise phase of the aeroplane.
Description
BACKGROUND OF THE INVENTION[0001]The present invention relates to the general field of turbomachine turbines for aeroplane gas-turbine engines. It relates more particularly to control of the clearance between, on the one hand, the tips of moving blades of a turbine rotor and, on the other hand, a turbine shroud of an outer casing surrounding the blades.[0002]To increase the performance of a turbine, it is a known practice to minimize to the extent possible the clearance existing between the tip of the turbine blades and the shroud that surrounds them. This blade tip clearance is dependent on the dimensional variations between the rotating portions (disk and blades constituting the turbine rotor) and the fixed portions (outer casing, including the turbine shroud that is part of it). These dimensional variations are both of thermal origin (connected with the variations in temperature of the blades, the disk and the casing) and of mechanical origin (connected in particular with the cen...
Claims
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Login to View More IPC IPC(8): F01D5/02
CPCF01D5/02F01D11/24
Inventor BONNEAU, DAMIENCROIXMARIE, MARCDENECE, FRANCK ROGER, DENISGAULLY, BRUNO ROBERT
Owner SN DETUDE & DE CONSTR DE MOTEURS DAVIATION S N E C M A