ELECTRIFIED DUAL PUMP FUEL SYSTEM WITH PARALLELIZATION

Abstract

A fuel delivery system for a gas turbine engine includes a fuel source and a main fuel pump configured to deliver a first fuel flow to a combustor assembly of the gas turbine engine during a first fuel-demanding operating condition of the gas turbine engine. A secondary fuel pump is arranged in fluidly parallel relationship with the main fuel pump. The secondary fuel pump is configured to deliver a second fuel flow to the combustor assembly during a second fuel-demanding operating condition of the gas turbine engine that is different from the first fuel-demanding operating condition.

Description

GENERAL STATE OF THE ART

[0001] Exemplary embodiments relate to the technology of gas turbine engines and in particular to fuel supply systems of gas turbine engines.

[0002] Fuel delivery systems for gas turbine engines utilize a multitude of pumps, often driven by a gearbox that extracts power from the gas turbine engine to drive the pumps. A common configuration is a fuel delivery system that includes two positive displacement pumps, both coupled to a fixed input, whose speed follows the engine speed, specifically the speed of the engine shaft to which the pumps are connected via the gearbox.

[0003] The pumping elements are typically sized to meet the requirements of engine start-up, the condition that places the greatest demand on the fuel delivery system. However, this excess pumping capacity is useless under other operating conditions, such as cruise operations, when the demands on the fuel delivery system are lower. Requirements for commercial fuel delivery systems regarding efficiency, cost, and reliability are constantly increasing. Therefore, a solution to improve the efficiency of the fuel delivery system under all operating conditions would be welcome in the field. SHORT DESCRIPTION

[0004] In an exemplary embodiment, a fuel delivery system for a gas turbine engine includes a fuel source and a main fuel pump configured to deliver a first fuel flow to a combustor assembly of the gas turbine engine during a first fuel-demanding operating condition of the gas turbine engine. A secondary fuel pump is arranged in fluidly parallel relationship with the main fuel pump. The secondary fuel pump is configured to deliver a second fuel flow to the combustor assembly during a second fuel-demanding operating condition of the gas turbine engine that is different from the first fuel-demanding operating condition.

[0005] Additionally or alternatively, in this or other embodiments, the secondary fuel pump is electrically driven.

[0006] Additionally or alternatively, in this or other embodiments, the first operating state is operation at cruise speed of the gas turbine engine.

[0007] Additionally or alternatively, in this or other embodiments, the second operating condition is one of engine start-up or below cruise operation of the gas turbine engine.

[0008] Additionally or alternatively, in this or other embodiments, a flow control device is configured to selectively control the fuel flow from the main fuel pump and the secondary fuel pump.

[0009] Additionally or alternatively, in this or other embodiments, operation of the main fuel pump is stopped when operation of the secondary fuel pump is started.

[0010] Additionally or alternatively, in this or other embodiments, the main fuel pump is mechanically driven via a gearbox of the gas turbine engine.

[0011] In another exemplary embodiment, a gas turbine engine and fuel delivery system includes a gas turbine engine including a turbine and a combustor in which fuel is combusted to drive the turbine via a flow of combustion products. A fuel delivery system is operatively connected to the gas turbine engine and includes a fuel source and a main fuel pump configured to supply a first fuel flow to the combustor during a first fuel-demanding operating condition of the gas turbine engine. A secondary fuel pump is disposed in fluidly parallel relationship with the main fuel pump. The secondary fuel pump is configured to supply a second fuel flow to the combustor during a second fuel-demanding operating condition of the gas turbine engine that is different from the first fuel-demanding operating condition.

[0012] Additionally or alternatively, in this or other embodiments, the secondary fuel pump is electrically driven.

[0013] Additionally or alternatively, in this or other embodiments, the first operating state is operation at cruise speed of the gas turbine engine.

[0014] Additionally or alternatively, in this or other embodiments, the second operating condition is one of engine start-up or below cruise operation of the gas turbine engine.

[0015] Additionally or alternatively, in this or other embodiments, a flow control device is configured to selectively control the fuel flow from the main fuel pump and the secondary fuel pump.

[0016] Additionally or alternatively, in this or other embodiments, operation of the main fuel pump is stopped when operation of the secondary fuel pump is started.

[0017] Additionally or alternatively, in this or other embodiments, the main fuel pump is mechanically driven via a gearbox of the gas turbine engine.

[0018] In another exemplary embodiment, a method for operating a gas turbine engine and fuel delivery system includes operating a gas turbine engine in a first fuel-demanding operating condition, supplying a first fuel flow to a combustion chamber of the gas turbine engine via a main fuel pump, switching operation of the gas turbine engine to a second operating condition different from the first operating condition, and starting operation of a secondary fuel pump arranged in fluidly parallel relationship to the main fuel pump. The secondary fuel pump is configured to supply a second fuel flow to the combustion chamber.

[0019] Additionally or alternatively, in this or other embodiments, operation of the main fuel pump is stopped when operation of the secondary fuel pump is started.

[0020] Additionally or alternatively, in this or other embodiments, the secondary fuel pump is electrically driven.

[0021] Additionally or alternatively, in this or other embodiments, the first operating state is operation at cruise speed of the gas turbine engine.

[0022] Additionally or alternatively, in this or other embodiments, the second operating condition is one of engine start-up or below cruise operation of the gas turbine engine.

[0023] Additionally or alternatively, in this or other embodiments, the main fuel pump is mechanically driven via a gearbox of the gas turbine engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following descriptions are not to be interpreted as limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: Fig. 1 is a schematic illustration of one embodiment of a gas turbine engine and fuel delivery system through which fuel is delivered to power the gas turbine engine; and Fig. 2 is a schematic illustration of an embodiment of a fuel delivery system of a gas turbine engine operating in a first mode. Fig. 3 is a schematic illustration of an embodiment of a fuel delivery system of a gas turbine engine operating in a second mode. Fig. 4 is a schematic illustration of an embodiment of a fuel delivery system of a gas turbine engine operating in a third mode. Fig. 5 is a schematic illustration of an embodiment of a fuel delivery system of a gas turbine engine operating in a fourth mode. DETAILED DESCRIPTION

[0025] A detailed description of one or more embodiments of the disclosed apparatus and method is provided herein with reference to the figures for purposes of illustration and not limitation.

[0026] A gas turbine engine system of an aircraft is in Fig. 1 is generally designated 10. The gas turbine engine system 10 includes a compressor section 12 operatively coupled to a turbine section 14 by a shaft 16. A combustor assembly 18 is fluidly connected between the compressor section 12 and the turbine section 14. A fuel delivery system 20 fluidly connects the combustor assembly 14 to a fuel source 24. The fuel delivery system 20 may receive fuel directly from the fuel source 24 or through a compressor stage (not shown) that creates an inlet pressure for the fuel. In addition to the combustor assembly 18, the fuel delivery system 20 may be operatively connected to one or more secondary components, such as a thrust augmentor 26, to deliver a fuel flow thereto. In some embodiments, a gearbox 28 is operatively connected to the gas turbine engine 10, for example, via the shaft 16, to extract power from the gas turbine engine 10.The fuel supply system 20 is operatively coupled to the transmission to supply power to components of the fuel supply system 20.

[0027] With reference to Fig. 2, the fuel delivery system 20 will now be described in more detail. The fuel delivery system 20 includes a main fuel pump 30 that delivers fuel to the combustion chamber assembly 18 via a main fuel path 32, with a combustion chamber fuel controller 34 located along the main fuel path 32 to control the flow of fuel to the combustion chamber assembly 18. Furthermore, in some embodiments, the main fuel pump 30 further delivers fuel via an actuation fuel line 38 to one or more actuators 36 to drive the operation of the actuators 36.

[0028] Fuel is introduced into the fuel supply system 20 from a fuel source 40, such as a fuel tank or the like. The fuel may first be passed through a booster pump 42 before passing through the main fuel pump 30. Both the main fuel pump 30 and the booster pump 42 are operatively connected to the transmission 28 and are mechanically driven by a pump shaft 46 connected to the transmission 28. The main fuel pump 30 is sized and configured to supply fuel to the combustor assembly 18 in the cruise operating condition of the gas turbine engine 10, but is undersized for other operating conditions, such as a takeoff and takeoff condition on hot days.For supplying fuel to the combustion chamber assembly 18 in operating conditions other than the cruise operating condition, the fuel supply system 20 further includes a secondary fuel pump 44 driven by an electric motor 48. The secondary fuel pump 44 is configured to supply fuel to the combustion chamber assembly 18 via a secondary fuel path 50 in operating conditions other than the cruise operating condition. For example, in operating conditions such as the start operating condition, the secondary fuel pump 44 is operated while the main fuel pump 30 is set to a bypass operating mode.In other operating conditions, such as a preceding cruising speed operating condition where greater fuel flow is required, the secondary fuel pump 44 is operated to supplement the operation of the main fuel pump 30 and provide additional fuel flow to the combustion chamber assembly 18 beyond that provided by the main fuel pump 30.

[0029] To enable operation in these various modes and switching between different operating modes, the fuel supply system 20 further includes a plurality of valves that interconnect the main fuel pump 30, the secondary fuel pump 44, the main fuel path 32, and the secondary fuel path 50. These valves include a selector valve 52, a pump sub-valve 54, and a combined windmill bypass valve / high pressure relief valve (WMBV / HPRV) 56. The WMBV / HPRV 56 is selectively switchable between operation as a WMBV or as an HPRV depending on the operating mode of the fuel supply system 20. Furthermore, a main check valve 58 may be located along the main fuel path 32 downstream of the main fuel pump 30, and a secondary check valve 60 may be located along the secondary fuel path 50 downstream of the secondary fuel pump 44.This prevents backflow to the pumps 30, 44 along the respective fuel path 32, 50. In some embodiments, a controller, such as a full authority digital engine control (FADEC), is connected to one or more of the main fuel pump 30, the secondary fuel pump 44, the selector valve 52, the pump sub-valve 54, and the WMBV / HPRV 56 to control their operation.

[0030] With reference to Fig. 2-5, the operation of the fuel supply system 20 in various operating modes will now be described in more detail. Fig. Figure 2 illustrates a pre-start condition. In the pre-start condition, the main fuel pump 30 provides only a low fuel flow due to the low speed of the gas turbine engine 10 driving the main fuel pump 30 and the low volumetric pump efficiency. Thus, the secondary fuel pump 44 is energized and operated to provide the fuel flow required in this operating condition. A problem present in this condition is that the breakaway torque required to start operation of the secondary fuel pump 44 is relatively high.To solve this problem and enable easier starting of the secondary fuel pump 44, the selector valve 52 is energized to transfer fuel from the main fuel pump 30 to a secondary pump inlet 62 of the secondary fuel pump 44, effectively overcoming the breakaway torque by unloading the bearing surfaces of the secondary fuel pump 44. This starting of the secondary fuel pump 44 via current from the main fuel pump 30 allows for a smaller electric motor 48, since 48 does not need to be sized to overcome the breakaway torque of the secondary fuel pump 44.In the pre-start condition, the secondary fuel pump 44 is capable of providing all required fuel flow to the combustion chamber assembly 18, so the pump sub-valve 54 is positioned in a first position to direct fuel from the secondary fuel path 50 toward the combustion chamber assembly 18 while the main fuel path 32 is blocked. Additionally, the WMBV / HPRV 56 is switched to the HPRV mode via the selector valve 52.

[0031] With reference to Fig. 3, power is increased toward cruise operation once the gas turbine engine 10 is started. From start-up operation until a pump switchover point at or near cruise operation, the secondary fuel pump 44 provides all fuel flow to the combustor assembly 18, and the main fuel pump 30 is operated in a bypass mode. To accomplish this, the WMBV / HPRV 56 is set to the WMBV mode, causing the main fuel pump 30 to operate in the bypass mode. The selector valve 52 is de-energized to transfer the main fuel pump 30 to the pump subvalve 54 and connect the boost pump 42 to the secondary pump inlet 62. In this mode, only the fuel from the secondary fuel pump 44 is directed to the combustor assembly 18.

[0032] With reference to Fig. 4, at a pump switchover operating point, which is at or near the cruise operating point, the main fuel pump 30 is used to provide fuel flow to the combustion chamber assembly 18 and the secondary fuel pump 44 is deactivated. To achieve this operation, the selector valve 52 is de-energized, transferring the main fuel pump 30 to the pump sub-valve 54 and connecting the boost pump 42 to the secondary pump inlet 62. The WMBV / HPRV 56 is set to the HPRV mode via the selector valve 52 and the pump sub-valve 54. The pump sub-valve 54 is set to a second position such that fuel flow is directed from the main fuel pump 30 and the main fuel path 32 to the combustion chamber assembly 18. The backflow of fuel to the secondary fuel pump 44 is stopped by the secondary check valve 60.By setting the pump sub-valve 54 to the second position, the pressure of the WMBV / HPRV 56 is further connected to a low pressure sink 66.

[0033] With reference to Fig.6, under operating conditions requiring a higher fuel flow than can be provided by the main fuel pump 30, the secondary fuel pump 44, which is in a fluidly parallel relationship with the main fuel pump 30, is activated to supplement the fuel flow provided by the main fuel pump 30 to the combustion chamber assembly 18. In this operating mode, the selector valve 52 is de-energized, transferring the main fuel pump 30 to the pump sub-valve 54 and connecting the boost pump 42 to the secondary pump inlet 62. The WMBV / HPRV 56 is set to the HPRV mode via the selector valve 52 and the pump sub-valve 54.The pump sub-valve 54 is set to a second position such that fuel flow from the main fuel pump 30 and the main fuel path 32 and fuel flow from the secondary fuel pump 44 are directed along the secondary fuel path 50 to the combustion chamber assembly 18.

[0034] It should be noted that the operating modes described herein are merely exemplary, and that arranging the main fuel pump 30 and the secondary fuel pump 44 in a fluidly parallel relationship, controlled through the use of the pump split valve 54 and the WMBV / HPRV 56, enables switching between the operation of the main fuel pump 30 and the secondary fuel pump 44, as well as supplementing the operation of the main fuel pump 30 with the operation of the secondary fuel pump 44. This allows the main fuel pump 30 to be sizing and configuring for the fuel flow requirements of cruise speed operation, while utilizing the operation of the secondary fuel pump 44 for other operating conditions. Sizing the main fuel pump 30 for cruise speed operation provides unique pump sizing and pump efficiency benefits to the fuel delivery system 20.

[0035] The term “approximately” is intended to include the degree of error associated with measuring the specific quantity based on the equipment available at the time of filing the application.

[0036] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It is further understood that the terms "comprises" and / or "comprising," when used in this specification, indicate the presence of stated features, integers, steps, acts, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, acts, elements, components, and / or groups thereof.

[0037] Although the present disclosure has been described with reference to an embodiment or embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. It is therefore intended that the present disclosure not be limited to the particular disclosed embodiment as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

[1] A fuel supply system for a gas turbine engine, comprising: a fuel source; a main fuel pump configured to supply a first fuel flow to a combustor assembly of the gas turbine engine in a first fuel-demanding operating condition of the gas turbine engine; and a secondary fuel pump arranged in fluidly parallel relationship to the main fuel pump, the secondary fuel pump configured to supply a second fuel flow to the combustor assembly during a second fuel demand operating condition of the gas turbine engine that is different from the first fuel demand operating condition. [2] The fuel supply system of claim 1, wherein the secondary fuel pump is electrically driven. [3] The fuel supply system of claim 1, wherein the first operating condition is operation at cruise speed of the gas turbine engine. [4] The fuel supply system of claim 1, wherein the second operating condition is one of engine start-up operation or below cruise speed of the gas turbine engine. [5] The fuel delivery system of claim 1, further comprising a flow control device configured to selectively control the flow of fuel from the main fuel pump and the secondary fuel pump. [6] A fuel supply system according to claim 1, wherein the operation of the main fuel pump is stopped when the operation of the secondary fuel pump is started. [7] A fuel supply system according to claim 1, wherein the main fuel pump is mechanically driven via a transmission of the gas turbine engine. [8] Gas turbine engine and fuel supply system comprising: a gas turbine engine comprising: a turbine; and a combustion chamber in which fuel is burned to drive the turbine via a stream of combustion products; and a fuel supply system operatively connected to the gas turbine engine, comprising: a fuel source; a main fuel pump configured to supply a first fuel flow to the combustion chamber in a first fuel-demanding operating condition of the gas turbine engine; and a secondary fuel pump arranged in fluidly parallel relationship to the main fuel pump, the secondary fuel pump configured to supply a second fuel flow to the combustion chamber during a second fuel demand operating condition of the gas turbine engine that is different from the first fuel demand operating condition. [9] A gas turbine engine and fuel delivery system according to claim 8, wherein the secondary fuel pump is electrically driven. [10] The gas turbine engine and fuel delivery system of claim 8, wherein the first operating condition is operation at cruise speed of the gas turbine engine. [11] A gas turbine engine and fuel delivery system according to claim 8, wherein the second operating condition is one of engine start-up or below cruise operation of the gas turbine engine. [12] The gas turbine engine and fuel delivery system of claim 8, further comprising a flow control device configured to selectively control fuel flow from the main fuel pump and the secondary fuel pump. [13] A gas turbine engine and fuel supply system according to claim 8, wherein the operation of the main fuel pump is stopped when the operation of the secondary fuel pump is started. [14] A gas turbine engine and fuel supply system according to claim 8, wherein the main fuel pump is mechanically driven via a transmission of the gas turbine engine. [15] A method of operating a gas turbine engine and fuel supply system, comprising: Operating a gas turbine engine in a first operating mode with fuel demand; Supplying a first fuel stream to a combustion chamber of the gas turbine engine via a main fuel pump; switching the operation of the gas turbine engine to a second operating state that is different from the first operating state; and Starting operation of a secondary fuel pump arranged in fluidly parallel relationship to the main fuel pump, the secondary fuel pump configured to supply a second fuel stream to the combustion chamber. [16] The method of claim 15, further comprising stopping operation of the main fuel pump when operation of the secondary fuel pump is started. [17] The method of claim 15, wherein the secondary fuel pump is electrically driven. [18] The method of claim 15, wherein the first operating condition is operation at cruise speed of the gas turbine engine. [19] The method of claim 15, wherein the second operating condition is one of engine start-up operation or below cruise speed of the gas turbine engine. [20] The method of claim 15, wherein the main fuel pump is mechanically driven via a transmission of the gas turbine engine.

Images