Turbojet comprising a bleeding system for bleeding air in said turbojet

A turbojet comprising a low-pressure compressor, a high-pressure compressor and a bleeding system configured to bleed air in the turbojet and to deliver the air to an air system. The bleeding system comprises a first air intake configured to bleed air at low pressure, a second air intake configured to bleed air at high pressure, a first valve and a second valve having inlets connected to the first air intake, a compressor having an inlet connected to an outlet of the second valve, a high-pressure valve connected to the second air intake, a control valve connected to the air system, and a controller to control opening and closing of the valves depending on a pressure at the first air intake.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 1451234 filed on Feb. 17, 2014, the entire disclosures of which are incorporated herein by way of reference.

BACKGROUND OF THE INVENTION

The present invention relates to an aircraft turbojet comprising a system for bleeding air from said turbojet, an aircraft comprising at least one such turbojet, and a method for controlling such a turbojet.

FIG. 1shows an aircraft bypass turbojet10equipped with a prior art bleeding system100that is intended to bleed air in the turbojet10and to deliver said air to an air system60, such as the conditioned air system60of the aircraft cabin.

The turbojet10comprises:a fan12intended to generate a flow of air in the turbojet10in a direction of displacement50of air in the turbojet, in which case, as is known, the flow of air then moves downstream of the fan in a primary vein of the turbojet10or in a secondary vein thereof,a compressor14that comprises a low-pressure compressor16downstream of the fan12and a high-pressure compressor18arranged downstream of the low-pressure compressor16,a turbine20that comprises a high-pressure turbine22downstream of the high-pressure compressor18and a low-pressure turbine24downstream of the high-pressure turbine22.

The air pushed by the fan and traveling in the primary vein then passes in succession through the low-pressure compressor16, the high-pressure compressor18, the high-pressure turbine22, and the low-pressure turbine24so as to be ejected to the outside.

Between the high-pressure compressor18and the high-pressure turbine22, the air passes through a combustion chamber26.

The high-pressure compressor18comprises a plurality of compression stages in which the pressure rises, from upstream to downstream in the direction of displacement50, from a low pressure at the first stage to a high pressure at the last stage, passing through an intermediate pressure in the vicinity of the middle stage.

The bleeding system100comprises:a first air intake102intended to bleed the air at the intermediate pressure in the high-pressure compressor18,a second air intake104intended to bleed the air at high pressure in the high-pressure compressor18,a check valve106fluidically connected to the first air intake102that prevents the air from moving toward said first air intake102,a high-pressure valve108fluidically connected to the second air intake104and controlled so as to be open or closed alternatively,a control valve110intended to control the pressure of the flow of air passing therethrough, the outlet of the high-pressure valve108and the outlet of the check valve106being fluidically connected to the same inlet of the control valve110,a cooler112intended to cool the air passing therethrough, the outlet of the control valve110being fluidically connected to an inlet of the cooler112and an outlet of the cooler112being fluidically connection to the air system60of the aircraft,a controller114intended to control the high-pressure valve108and the control valve110.

The air necessary for the cooling performed in the cooler112is bled through a system of pipes116arranged downstream of the fan12in the secondary air vein of the turbojet10.

The air pressure at the outlet of the cooler112must be compatible with the air pressure that must be injected in the air system60. In the case of a pressurized cabin, the air pressure typically must be between 137895.14 Pa (20 psia) and 206842.72 Pa (30 psia).

Thus, when the pressure at the first air intake102is above a first threshold, typically 275790.29 Pa (40 psia), the air necessary for operation of the bleeding system100is bled at the first air intake102, and when the pressure in the bleeding system100is below a second threshold, typically 206842.72 Pa (30 psia), the air necessary for operation of the bleeding system100is bled at the second air intake104.

To this end, a pressure sensor measures the value of the pressure at the first air intake102and another pressure sensor111measures the value of the pressure in the bleeding system100. Such a pressure sensor111is installed, for example, downstream of the junction between the outlet of the check valve106and the outlet of the high-pressure valve108.

The bleeding system100then operates as follows:when the pressure at the first air intake102is above a first threshold, the controller114orders the closure of the high-pressure valve108,the air is then bled at the first air intake102, passes through the check valve106and supplies the control valve110,when the pressure in the bleeding system100is below the second threshold, the controller114orders the opening of the high-pressure valve108,the air is then bled at the second air intake104, passes through the high-pressure valve108and supplies the control valve110, and the check valve106prevents the air from returning to the turbojet10,the controller114controls the control valve110in accordance with the air pressure that is to be obtained,the air at the outlet of the control valve110passes through the cooler112, then supplies the air system60.

Such a layout is not always satisfactory in terms of energy consumption.

SUMMARY OF THE INVENTION

One object of the present invention is to propose a turbojet comprising a bleeding system that does not demonstrate the disadvantages of the prior art and that in particular allows a reduction of consumption.

To this end, a turbojet comprising a low-pressure compressor, a high-pressure compressor with a number of compression stages in which the pressure rises, from upstream to downstream in a direction of displacement of the air, from a low pressure to a high pressure, and a bleeding system intended to bleed air in the turbojet and to deliver said air to an air system are proposed, the bleeding system comprising a second air intake intended to bleed air at high pressure in the high-pressure compressor,

said bleeding system further comprisinga first air intake intended to bleed air at low pressure,a first valve of which the inlet is fluidically connected to the first air intake,a second valve of which the inlet is fluidically connected to the first air intake,a compressor of which the inlet is fluidically connected to the outlet of the second valve,a check valve of which the inlet is fluidically connected to the outlet of the first valve and to the outlet of the compressor, and which prevents the air from moving toward the compressor and the first valve,a high-pressure valve fluidically connected to the second air intake,a cooler intended to cool the air passing therethrough, the outlet of the high-pressure valve being fluidically connected to an inlet of the cooler,a control valve intended to control the pressure of the flow of air passing therethrough, the outlet of the cooler and the outlet of the check valve being fluidically connected to the same inlet of the control valve, and an outlet of the control valve being fluidically connected to the air system,a controller intended to control the opening and closing of the high-pressure valve, the first valve, the second valve and the control valve, anda pressure sensor intended to measure the value of the pressure at the first air intake and to transmit information concerning this pressure to the controller.

This particular arrangement makes it possible to reduce the consumption of fuel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4shows an aircraft400equipped with a bypass turbojet10.

FIG. 2andFIG. 3show the turbojet10equipped with a bleeding system200,300according to the invention that is intended to bleed air in the turbojet10and to deliver said air to an air system60, such as the conditioned air system60of the aircraft cabin.

The turbojet10comprises the same elements as that inFIG. 1, in particular a low-pressure compressor16and a high-pressure compressor18. These elements bear the same references.

The high-pressure compressor18comprises a number of stages of compression in which the pressure rises, from upstream to downstream in a direction of displacement of the air50in the turbojet, from a low pressure at the first stage to a high pressure at the last stage.

The bleeding system200ofFIG. 2comprises:a first air intake202intended to bleed air at low pressure,a second air intake204intended to bleed air at high pressure in the high-pressure compressor18,a first valve215of which the inlet is fluidically connected to the first air intake202, and controlled so as to be open or closed alternatively,a second valve216of which the inlet is fluidically connected to the first air intake202, and controlled so as to be open or closed alternatively,a compressor218of which the inlet is fluidically connected to the outlet of the second valve216,a check valve206of which the inlet is fluidically connected to the outlet of the first valve215and to the outlet of the compressor218, and which prevents the air from moving toward the compressor218and the first valve215,a high-pressure valve208fluidically connected to the second air intake204and controlled so as to be open or closed alternatively,a cooler212intended to cool the air passing therethrough, the outlet of the high-pressure valve208being fluidically connected to an inlet of the cooler212,a control valve210intended to control the pressure of the flow of air passing therethrough, the outlet of the cooler212and the outlet of the check valve206being fluidically connected to the same inlet of the control valve210, and an outlet of the control valve210being fluidically connected to the air system60of the aircraft, anda controller214intended to control the opening and closing of the high-pressure valve208, the first valve215, the second valve216and the control valve210depending on the pressure at the first air intake202.

The first air intake202is arranged so as to bleed low-pressure air at the low-pressure stages of the high-pressure compressor18or at the low-pressure compressor16.

The air necessary for the cooling performed in the cooler212is bled here by means of a system of pipes116arranged downstream of the fan12in the secondary air vein of the turbojet10.

The air pressure at the outlet of the control valve210must be compatible with the air pressure that must be injected in the air system60. In the case of a pressurized cabin, the air pressure typically must be between 137895.14 Pa (20 psia) and 206842.72 Pa (30 psia). The controller214thus controls the opening of the control valve210in accordance with the pressure to be delivered.

Typically, in a turbojet10in takeoff mode, the pressure of the air at the first air intake202, that is to say the low pressure, is approximately 206842.72 Pa (30 psia), and during idling the pressure of the air at the second air intake204, that is to say the high pressure, is approximately 137895.14 Pa (20 psia).

Thus, when the pressure at the first air intake202is above a first threshold, typically approximately 137895.14 Pa (20 psia), the air necessary for operation of the bleeding system200is bled at the first air intake202, when the pressure at the first air intake202is below the first threshold and above a second threshold, typically approximately 103421.36 Pa (15 psia), the air necessary for operation of the bleeding system200is bled at the first air intake202and compressed by the compressor218, and when the pressure at the first air intake202is below the second threshold, the air necessary for operation of the bleeding system200is bled at the second air intake204.

For this purpose, a pressure sensor203measures the value of the pressure at the first air intake202and transmits the information concerning this pressure to the controller214so that said controller controls the opening and closing of the appropriate valves.

Thus, when the pressure at the first air intake202is above the first threshold, the controller214orders the opening of the first valve215, the closing of the second valve216, and the closing of the high-pressure valve208.

The air coming from the first air intake202then passes in succession through the first valve215, the check valve206and the control valve210and is guided to the air system60.

Thus, when the pressure at the first air intake202is below the first threshold and above the second threshold, the controller214orders the closing of the first valve215, the opening of the second valve216, and the closing of the high-pressure valve208.

The air coming from the first air intake202then passes in succession though the second valve216, the compressor218, the check valve206and the control valve210and is guided to the air system60.

Thus, when the pressure at the first air intake202is below the second threshold, the controller214orders the closing of the first valve215, the closing of the second valve216, and the opening of the high-pressure valve208.

The air coming from the second air intake204then passes in succession through the high-pressure valve208, the cooler212and the control valve210and is guided to the air system60. The check valve206then prevents the air coming from the cooler212from returning toward the first air intake202.

A method for controlling the turbojet10thus comprises:a first control step during which the controller214orders the opening of the first valve215, the closing of the second valve216, and the closing of the high-pressure valve208when the pressure at the first air intake202is above the first threshold,a second control step during which the controller214orders the closing of the first valve215, the opening of the second valve216, and the closing of the high-pressure valve208when the pressure at the first air intake202is below the first threshold and above the second threshold, anda third control step during which the controller214orders the closing of the first valve215, the closing of the second valve216, and the opening of the high-pressure valve208when the pressure at the first air intake202is below the second threshold.

These three steps are alternative and the controller214performs one or the other after having compared the value of the pressure measured by the pressure sensor203in relation to the first threshold and the second threshold.

The displacement of the air intake from intermediate pressure to low pressure makes it possible to save fuel during the take-off, ascent and cruising. Depending on the structure of the turbojet10, the saving can be from 0.7% to 1.7%.

In the embodiment of the invention inFIG. 2, the compressor218is driven by an electric power source of the aircraft.

FIG. 3shows a bleeding system300in which the compressor218is driven with the aid of a bleed of air performed within said bleeding system300.

The bleeding system300thus also comprises:a compression valve302of which the inlet is fluidically connected to the outlet of the second valve216, anda turbine304of which the inlet is fluidically connected to the outlet of the compression valve302and which is intended to drive the compressor218.

The controller214is then also provided in order to control the opening and closing of the compression valve302.

The operation of the bleeding system300is thus identical to that of the first embodiment when the pressure at the first air intake202is above the first threshold and when the pressure at the first air intake202is below the second threshold. The controller214thus orders the closing of the compression valve302.

By contrast, when the pressure at the first air intake202is below the first threshold and above the second threshold, the controller214orders the closing of the first valve215, the opening of the second valve216, the closing of the high-pressure valve208and the opening of the compression valve302.

During the second control step, the controller214also orders the opening of the compression valve302.

The air coming from the first air intake202then passes in succession through the second valve216, the compressor218, the check valve206and the control valve210and is guided to the air system60, whereas some of the air is bled at the outlet of the second valve216in order to pass through the compression valve302and then supply the turbine304.

The controller214orders the opening of the compression valve302in order to distribute the air between the compressor218and the turbine304. In accordance with one particular embodiment, 66% of the air coming from the second valve216passes through the compressor218and 33% passes through the turbine304.