POWER WITHDRAWAL FROM A LP BODY AND SYSTEM FOR REMOVING DEBRIS

Abstract

The invention concerns a bypass turbomachine (1) with a primary flow path and a secondary flow path, comprising: —a low-pressure body comprising a low-pressure compressor (120) connected to a low-pressure turbine (122) via a low-pressure shaft (124), —a high-pressure body comprising a high-pressure compressor (130) connected to a high pressure turbine (132), via a high-pressure shaft (134), —a low-pressure power take-off system (220) comprising an electrical generator (226), configured to take power (W12) from the low-pressure body, wherein—the turbomachine comprises a debris removal system (500), located between the two compressors (226, 236), —the low-pressure power take-off system (220) is configured to take power (W12) from the low-pressure shaft (124) using the resistive torque of the electrical generator (226), in order to avoid a risk of surging.

Claims

1. A bypass gas turbine engine comprising: a low-pressure spool comprising a low-pressure compressor connected to a low-pressure turbine via a low-pressure shaft; a high-pressure spool comprising a high-pressure compressor connected to a high-pressure turbine, via a high-pressure shaft, a low-pressure power withdrawal system comprising an electrical generator and, configured to withdraw power from the low-pressure spool, wherein the low-pressure power withdrawal system is configured to withdraw power from the low-pressure shaft using a resistive torque of the electrical generator on a withdrawal command of an electronic control unit to slow down the low-pressure compressor and avoid a risk of a surge between the high-pressure compressor and the low-pressure compressor; and a debris expulsion system, located between the low-pressure compressor and the high-pressure compressor.

2. The gas turbine engine of claim 1, wherein the debris expulsion system is further configured to be activated when hail or water is ingested, on command of an electronic control unit.

3. The gas turbine engine of claim 1, further comprising a debris detection device configured to detect a presence of debris between the low-pressure compressor and the high-pressure compressor, wherein the debris expulsion system is configured to only be activated if the debris detection device detects debris, on command of an electronic control unit.

4. The gas turbine engine of claim 1, wherein the power withdrawal is configured to be controlled as a function of ratings of the low-pressure compressor and of the high-pressure compressor, on command of an electronic control unit.

5. The gas turbine engine of claim 4, wherein the electronic control unit controls the power withdrawal as a function of an instantaneous variations of ratings of the low-pressure compressor and of the high-pressure compressor.

6. The gas turbine engine of claim 1, wherein the debris expulsion system comprises at least one door suitable for being opened in a go no-go arrangement.

7. The gas turbine engine of claim 1, wherein the debris expulsion system is further configured to be controlled in a go no-go arrangement, on command of an electronic control unit.

8. The gas turbine engine of claim 1, further comprising a dedicated electronic control unit, separate from a main electronic control unit of the gas turbine engine, and configured to control the power withdrawal as a function of an instantaneous variations of ratings of the low-pressure compressor and of the high-pressure compressor, on command of the main electronic control unit.

9. The gas turbine engine of claim 1, wherein the debris expulsion system is further configured to be controlled in a go no-go arrangement, on command of an electronic control unit, in the event of a failure to maintain a surge margin through the low-pressure power withdrawal system, to expel an overpressure between the low-pressure compressor and the high-pressure compressor.

10. A propulsion assembly for an aircraft, comprising the gas turbine engine of claim 1 and an on-board electronic control unit able to generate the withdrawal command to slow down the low-pressure compressor.

Description

OVERVIEW OF THE FIGURES

[0034] Other features, aims and advantages of the invention will become apparent from the following description, which is purely illustrative and non-limiting, and which must be read with reference to the appended drawings, wherein:

[0035] FIG. 1 shows a gas turbine engine.

[0036] FIG. 2 shows a functional block diagram of a VBV of the prior art.

[0037] FIG. 3 shows a schematic view of a gas turbine engine according to an embodiment of the invention.

[0038] FIG. 4 shows a functional block diagram of an embodiment of a gas turbine engine according to an embodiment of the invention.

DETAILED DESCRIPTION

[0039] With reference to FIG. 3, a generic primary airflow of a bypass twin-spool fan gas turbine engine 100 can be seen, along with a portion of a secondary airflow.

[0040] It conventionally comprises, from upstream to downstream in the direction of flow of the gas, a fan 110, a low-pressure compressor 120, a high-pressure compressor 130, a combustion chamber 140, a high-pressure turbine 132, a low-pressure turbine 122 and a primary exhaust nozzle 140. The LP compressor (or booster) 120 and the LP turbine 122 are connected by a low-pressure shaft 124 and together form a low-pressure LP spool. The HP compressor 130 and the turbine 132 are connected by a high-pressure shaft 134 and together form, with the combustion chamber 140, a high-pressure HP spool.

[0041] The fan 110, which is driven, either directly, or by way of a reduction gear, by the LP shaft 124, compresses the air coming from the air intake scoop. This air is divided downstream of the fan between a secondary air flow FS which is directed directly toward a secondary nozzle through which it is ejected to participate in the thrust provided by the engine, and a so-called primary flux FP which enters into the gas generator, formed of the HP and LP bodies, then is ejected into the primary nozzle 140. The invention also covers the case where the two flows, primary and secondary are mixed before ejection.

[0042] Mechanical power is withdrawn from the shafts 124, 134, by example by direct drive or through power drives or via a reduction gear if the engine has one.

[0043] Where the LP spool is concerned, a power W12 is withdrawn, i.e. recovered, by an LP power withdrawal system 220, through a power drive 222 (or direct drive), either at the level of the LP compressor 120, the LP turbine 122, or at any other place on the LP shaft 124.

[0044] This power drive 222 can open onto a reduction gear 224 which is itself connected to an electrical generator 226 which converts the received power W12 into electrical power.

[0045] This can, as shown in FIG. 2, be stored in an electrical power storage means 300 or else sent directly, via an electrical motor for power injection, to one of the gas turbine engine shafts.

[0046] The electrical power storage means 300 can conventionally be a battery, for example of lithium-ion type, or for example a supercapacitor. Power electronics will generally interface between the generator and the power storage means 300.

[0047] In the same way, a power W13 can be withdrawn from the HP spool, by an HP power withdrawal system 230, either at the level of the turbine or at any other place on the HP shaft 20. Here again, it is extracted by an HP power drive 232 (or by direct drive). This power drive 232 can also generally open into a reduction gear 234 which is itself connected to an electrical generator 236 which converts the received power W13 into electrical power.

[0048] As previously, the reduction gear 234 is connected to an electrical generator 236 which converts the received energy W13 into electrical power.

[0049] This can, as is shown in FIG. 3, be stored in the electrical power storage means 300, which can be the same as for the energy W12.

[0050] In an embodiment, the generators 226, 236 are separate, and preferably housed in axially and/or circumferentially different places in the gas turbine engine. However, it is possible, by way of residual current devices or coupling, to use a single generator which can withdraw from the LP spool or the HP spool.

[0051] The gas turbine engine 100 further comprises an electronic control unit 400 configured to receive sensor data, pilot instructions, setpoints etc. to process them and to issue commands, information, etc. The electronic control unit 400 is generally an on-board main electronic control unit, of FADEC (Full Authority Digital Engine Control) type which acts as the interface between the cockpit of the aircraft and the gas turbine engine 100. The main electronic control unit of FADEC type is integrated into the propulsion assembly which comprises the gas turbine engine. It is for example installed in a compartment of a nacelle surrounding the gas turbine engine, but it can also be outside the perimeter of the gas turbine engine, such as in the mast or the fuselage of the aircraft. It comprises one or more processors and memory needed to process the data. Alternatively, the electronic control unit 400 can be separate from the main electronic control unit of FADEC type. Alternatively, several electronic control units, including a FADEC on-board electronic control unit, are provided, and share the actions.

[0052] The power withdrawal can be activated or deactivated on command of the electronic control unit 400. To do this, it is assumed that the power withdrawal systems 220 and 230 dispose of appropriate technical means, known to those skilled in the art and not detailed here. These means may consist in clutches, couplings, free wheels etc., or else have a generator constantly driving the power electronics that drive the power withdrawal. The power withdrawal can also be activated at different levels: the power withdrawal system 220, 230 disposes of suitable power electronics, known to those skilled in the art.

[0053] The LP power withdrawal system 200 has the function of slowing down the N1 rating, i.e. the low-pressure spool and more specifically the low-pressure compressor 120 to avoid the risk of surges. To do this, the LP power withdrawal system 200 receives a withdrawal command CP from the electronic control unit 400 which has been generated taking into account the N1 rating of the low-pressure compressor 120 and the N2 rating of the high-pressure compressor 130, giving CP=f(N1, N2, t) where f represents a function and t time. The withdrawal command CP also takes into account the Mach number and pressure, giving CP=f(N1, N2, t, Mach number, Pressure). This law is called LS in FIG. 4.

[0054] Moreover, it is still possible to take into account the OK and OD information described in the introduction.

[0055] The data N1 and N2 may be obtained from computation or estimation.

[0056] More specifically, the withdrawal command CP depends on the variations of the N1 and N2 ratings. This gives CP=f(dN1/dt, dN2/dt, t, Mach number, Pressure) where f represents a function.

[0057] In a particular embodiment, the withdrawal command CP is generated, for a given pressure and Mach number, as soon as a difference between dN1/dt and dN2/dt is greater than a certain threshold. This results in a slowdown of the LP shaft substantially adapted to that of the HP shaft.

[0058] The data dN1/dt and dN2/dt may be computed by the electronic control unit 400 or, for more responsiveness, by a dedicated electronic control unit (not shown) at the level of the generator or generators.

[0059] Thus, the resistive torque of the generator 226 is used to slow down the LP compressor 120. The electricity produced by the generator 226 can be used in different ways (storage or reinjection into another shaft). The document WO2016/020618 describes different solutions.

[0060] Use of the VBV system to satisfy the operability requirements of the gas turbine engine is no longer necessary. Use of the VBV system does however remain necessary to expel debris.

[0061] However, the management of debris expulsion is no longer provided. To do this, the gas turbine engine 100 comprises a debris expulsion system 500 comprising a door 502 opening between the two LP 120 and HP 130 compressors, an expulsion airflow 504 and an outlet 506 opening into the secondary airflow. There is a plurality of doors 502 and outlets 506 circumferentially around the shaft of the gas turbine engine. The debris expulsion system 500 can be housed in an intermediate casing.

[0062] The debris expulsion system can be structurally similar to VBVs. However, it is not activated in the same phases.

[0063] These different phases are illustrated in FIG. 4, by comparison with FIG. 2 of the prior art.

[0064] The debris expulsion system 500 is driven on an electronic control unit command 400.

[0065] Provision is also made for a debris detection device 510. The detection can where applicable be direct, for example on the basis of an optoelectronic system for detecting objects from a certain height and above, entering the LP compressor and/or building up at the inlet of the HP compressor. This detection device 510 may also react to a risk of debris being present, for example by taking into account the pressure prevailing between the two HP or LP compressors, or else other parameters which are modified in the presence of debris. For example, it can detect conditions favorable to the appearance of a surge which might be caused by the overall dimensions of the inlet of the HP compressor. The debris detection device 510 generates a signal SD which is sent to the electronic control unit 400 when debris is detected (or suspected).

[0066] Owing to an implemented ingestion law LI, the electronic control unit 400 generates an activation command CA to activate the debris expulsion system only when the debris detection system detects debris. This means that the debris expulsion system 500 is relatively little-used by comparison with a conventional VBV system. Stress is lower, as is wear.

[0067] It may occur that the command CP is not enough to sufficiently slow down the LP compressor, or that the slowdown of the LP compressor is not enough to move away from the surge region. To palliate this, a protection law LPB of the LP compressor is implemented: it generates an activation command CA of the debris expulsion system to expel overpressure. In an embodiment, the criterion is a latency time between 2s and 5s if the application of a resistive torque does not have the desired effect on the surge margin.

[0068] The debris expulsion system 500 can be of a more simple design than VBVs. One example that can be mentioned is the doors 502 which can be designed to be in two states only: open or shut (go no-go). Similarly, the commands generated by the electronic control unit 400 can be binary and thus correspond either to an open door or to a shut door.

[0069] In a particular embodiment, the invention can be implemented on the basis of an existing gas turbine engine comprising an LP withdrawal system and a VBV system.

[0070] The invention can also be described as a method comprising a step in which the VBV system is activated under the aforementioned conditions for the debris expulsion system 500. The VBV system is therefore generally no longer activated to improve the surge margin, since this function is fulfilled by the activation of the power withdrawal system under the aforementioned conditions.