Aircraft energy management system including engine fan discharge air boosted environmental control system

An aircraft energy management system including a cabin air compressor adapted to be coupled to a source of fan discharge air at a first pressure during an inflight operating mode and adapted to be coupled to a ram intake air during a ground operating mode. The system further including an environmental control system mechanically coupled to a compressor exit of the cabin air compressor. The aircraft energy management system configured to provide a conditioned fluid flow to an aircraft cabin, cockpit or de-icing system.

BACKGROUND

Embodiments disclosed herein relate generally to aircraft energy management systems including environmental control systems and more particularly to methods and apparatus for extracting fan discharge air to boost an aircraft environmental control system.

Turbine-powered aircraft conventionally incorporate environmental control systems (ECS) which control aircraft cabin temperature by the amount and temperature of a bleed air extracted from an engine. Historically, ECS have used engine bleed air that is extracted from a high pressure compressor (HPC) or is generated by means of a compressor that is driven by an auxiliary gas turbine (“APU”), throttled (pressure reduced), and cooled by a heat exchanger (“precooler”) using fan bleed air. Bleed air is also used to provide anti-icing to the aircraft, and must be at high temperature for this purpose—typically about 204° C. (400° F.).

Aircraft weight is a current concern in the current industry, with a decrease in aircraft weight resulting in an efficiency increase. In light of the concern, future aircraft will replace some or all of their metallic structures with composite materials to reduce weight and improve overall efficiency. These structures have limited temperature capability compared to metal alloys. For example, a typical carbon-fiber composite material may have a temperature limit substantially below 93° C. (200° F.). Conventional ECS interfaces, utilizing engine bleed air cannot meet this requirement without significantly increasing the size of an included precooler. Furthermore, composite aircraft will often use electrically powered anti-ice systems and therefore do not require high temperature bleed air.

One way ECS requirements have been met in composite aircraft, is by using electrically driven ECS to pressurize and condition ambient air. While effective to provide low-pressure, low-temperature bleed air, this requires a separate air inlet to efficiently entrain ambient fresh air, an additional air intake for cooling and considerable electrical power to drive the ECS compressors. The electrical power requirements can require an undesirable increase in the size of the engine mounted generators. In addition, the air intakes will produce drag on the aircraft, translating to an increase in fuel burn and therefore cost of operation. These weight and drag penalties of electrically driven ECS are also of concern in smaller aircraft.

Accordingly, there is a need for an improved environmental control system and method for extracting engine discharge air that will reduce aircraft weight and minimize drag air penalties.

BRIEF SUMMARY OF THE INVENTION

These and other shortcomings of the prior art are addressed by the present disclosure, which provides an aircraft energy management system that provides an engine fan discharge air boosted aircraft environmental control system which is effective to extract fan discharge air from a turbine engine and provide airflow to an aircraft environmental control system. The aircraft energy management system is configured to benefit from the fan pressure ratio and reduced ram air drag losses, while minimizing overall aircraft weight.

In accordance with an embodiment, an aircraft energy management system is provided. The aircraft management system including a cabin air compressor and an environmental control system mechanically coupled to a compressor exit of the cabin air compressor. The cabin air compressor is adapted to be coupled to a source of fan discharge air at a first pressure during an inflight operating mode and adapted to be coupled to a ram intake air during a ground operating mode.

In accordance with another embodiment, an aircraft energy management system is provided. The aircraft management system including a gas turbine engine, a cabin air compressor mechanically coupled to the gas turbine engine and an environmental control system mechanically coupled to the cabin air compressor. The gas turbine engine comprising a turbomachinery core including a high pressure compressor, a combustor, and a high pressure turbine in serial flow relationship. The core is operable to produce a first pressurized flow of air and a low pressure turbine disposed downstream of the core and operable to drive a fan to produce a second pressurized flow of air. The cabin air compressor having a compressor inlet coupled to the fan and a fresh air intake. The cabin air compressor is configured to receive the second pressurized flow of air from the fan during an inflight operating mode and a ram air fluid flow at a second pressure during a ground operating mode and discharge a compressed fluid flow at a third pressure substantially higher than the first pressure and the second pressure. The environmental control system is mechanically coupled to the cabin air compressor and having an inlet coupled to a compressor exit of the cabin air compressor to receive the compressed fluid flow and discharge a conditioned fluid flow.

In accordance with yet another embodiment, a method of extracting fan discharge air from a gas turbine engine in an energy management system is provided. The method including extracting a fan discharge air flow at a first temperature and a first pressure from a fan of the engine; compressing the fan discharge air flow through a cabin air compressor so as to increase its temperature and pressure and discharge a compressed fluid flow at a second temperature and a second pressure; and passing the compressed fluid flow through an environmental control system mechanically coupled to the cabin air compressor and discharging a conditioned fluid flow.

Other objects and advantages of the present disclosure will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.

DETAILED DESCRIPTION

Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,FIG. 1depicts in a simplified block diagram, elements of an exemplary aircraft energy management system10including a gas turbine engine12in fluidic communication with an electrically driven cabin air compressor (CAC)14, a means for providing ground power16and an environmental control system (ECS)18. The engine12having an engine fan20, a high pressure compressor22, a combustor24, a high pressure turbine26, and a low pressure turbine28, all arranged in a serial, axial flow relationship. Collectively the high pressure compressor22, the combustor24, and the high pressure turbine26are referred to as a “core”25. The fan20providing intake air to the high pressure compressor22. The high pressure compressor22provides compressed air that passes into the combustor24where fuel is introduced and burned, generating hot combustion gases. The hot combustion gases are discharged to the high pressure turbine26where they are expanded to extract energy therefrom. The high pressure turbine26drives the compressor22through a shaft30. Pressurized air exiting from the high pressure turbine26is discharged to the low pressure turbine28where it is further expanded to extract energy. The low pressure turbine28drives the fan20through an inner shaft32. The fan20generates a flow of pressurized air, a portion of which supercharges the inlet of the high pressure compressor22, a portion of which is provided as discharge air34to the cabin air compressor14, and another portion of which bypasses the “core” to provide the majority of the thrust developed by the engine10. While not shown inFIG. 1, it will be understood that the engine fan20, the high pressure compressor22, the combustor24, the high pressure turbine26, and the low pressure turbine28are all enclosed in a suitable housing(s) and that the shafts30,32are supported in bearings of a known type to absorb thrust and radial loads.

The engine10is in fluidic communication with the downstream positioned cabin air compressor14. In an embodiment, the cabin air compressor14is electrically powered via power extracted from the engine10during flight mode or via the means for providing ground power16. More particularly, during flight, all electrical power required to power the CAC14is extracted from the main engine10. In an alternate embodiment, the CAC14is configured as a bleed driven or shaft driven compressor. In an embodiment, during ground mode operation, the means for providing ground power16may be comprised of an external auxiliary power unit (APU), wherein power and air requirements are packaged for use when the aircraft is on the ground, thereby minimizing the need to power the aircraft's on-board APU or engine10. The means for ground power16allows for aircraft cockpit and cabin conditioning without the need to operate the main engine10. In a preferred embodiment, the means for providing ground power16is an APU delivering electric power only. Additionally, it is anticipated that the means for ground power16may be provided by any alternate means for providing power known in the art, such as, but not limited to, ground power unit, or the like.

In the illustrated example, the energy management system10further includes a ram air intake63in fluidic communication with the CAC14, and more particularly the CAC compressor (described presently). In accordance with conventional practice, the ram air intake63is selectively opened or closed by an actuator of a known type in response to control signals, to control the intake of ram air to the CAC compressor14while the aircraft is on the ground and when the aircraft is in flight. More specifically, in an embodiment the ram air intake63includes a door (not shown) that is opened when the aircraft is on the ground and closed when the engine12is started and the air intake for the CAC14is switched to the engine fan discharge fluid flow34.

In the embodiment illustrated inFIG. 1, the discharge air34entering the CAC14is obtained from the engine fan20, as engine fan discharge air34via an inlet duct35, or from the ram air intake63, dependent upon mode of operation. During a flight mode of operation, providing discharge air34to the CAC14enables the CAC14to benefit from the pressure rise through the engine fan20and reduced ram air drag losses. The fluid flow36is pressurized air whose pressure is raised by the CAC14. In addition to providing for heating or cooling, it may be used for purposes such as anti-icing or de-icing, pressurization and operating pneumatic equipment. In the described embodiment it may be used for an environmental control system (ECS)18. It is necessary to supply the ECS18with this fan discharge air34as a first compressed fluid flow36via a duct37at specified temperature and pressure conditions, and at a sufficient mass flow rate.

The CAC14described herein is configured to receive fan discharge air34, and provides a low pressure, low temperature interface to the engine12that is compatible with the temperature limitations of carbon-fiber composite wing, weight restrictions and minimization of drag losses of aircraft. The CAC14provides a high pressure and high temperature interface and boosted power to the ECS18through a first compressed air flow36without adversely increasing the size and thus weight of the overall energy management system10.

Referring now toFIGS. 2-7, illustrated are embodiments of the energy management system10including alternate environmental control systems and illustrating operation in cooling, partial cooling and heating modes, both during flight and when the aircraft is on ground. It should be understood that in the illustrated alternative operation modes, specific system elements may be shown in phantom to indicate non-use during that specific mode.

Referring more specifically toFIGS. 2-4, illustrated is an energy management system40, generally similar to energy management system10ofFIG. 1. In the embodiment illustrated inFIGS. 2-4, the energy management system40, and more particularly the ECS18is configured as an air cycle machine (ACM)64. In an embodiment, the ACM64is laid out as a three-wheel system and is powered by the CAC14flow, and more particularly, the first compressed fluid flow36. Depending on air conditioning needs, there are three main operation modes illustrated for the energy management system40to provide conditioned air to the cabin/cockpit: a ground cooling mode (FIG. 2), a flight partial cooling mode (FIG. 3) and a flight heating mode (FIG. 5). It should be understood that heating, partial cooling and cooling modes may be operated during in flight, or on ground, dependent upon configuration and power source (i.e. engine or ground power source). As best illustrated throughoutFIGS. 2-7, the double solid lines indicate refrigerated airflow and the dashed line indicates heated airflow.

Energy management system40includes an engine12, a CAC14, a means for providing ground power16and an ECS18. In addition, illustrated inFIGS. 2-4are an optional liquid cooling loop42, a fuel loop44and an oil and lube system46configured in fluid communication with the ECS18. In an embodiment, the liquid cooling loop42is a propylene glycol/water (PGW) liquid cooling loop and may be included to cool a CAC motor controller. The liquid cooling loop42may include a PGW heat exchanger48, a liquid cooled motor drive50, a PGW pump52and a bypass valve54. Additionally, illustrated inFIGS. 2-4is a source of fuel56, such as a fuel tank57including at least one fuel pump58, in fluidic communication with a fuel heat exchanger59.

Referring more specifically toFIG. 2, during the illustrated ground cooling mode, power is provided by the means for ground power16, which in this particular embodiment is an APU60, as previously described. In the illustrated ground cooling mode, the engine12is in an off mode and thus shown in shadow. A ram air43entering the CAC14is obtained from the ram air intake63via an inlet duct65. The ram air43is input at an atmospheric pressure. The ram air43is directed toward the CAC14and compressed by a compressor62of CAC14, generating the first compressed36at a pressure higher than the ram air43pressure. The first compressed fluid flow36is directed to the ECS18system via the duct37. As previously indicated, in the illustrated embodiment, ECS18is configured as an air cycle machine (ACM)64. During the ground cooling mode, the first compressed fluid flow36enters the ACM64, passing through a primary heat exchanger66, an ACM air compressor68, a secondary heat exchanger70, a turbine72and a condenser74before exiting the ACM64as a cooled compressed fluid flow76. Cooling of the first compressed fluid flow36is provided in the primary and secondary heat exchangers66,70wherein the first compressed fluid flow36is circulatable in heat exchange relationship with a portion of a ram air intake fluid flow80for cooling of the first compressed fluid flow36in the ACM64. The primary ACM heat exchange unit66and the secondary ACM heat exchange unit70function to cool the first compressed fluid flow36in the energy management system40.

In the illustrated ACM embodiment, there are two instances of heat exchange (may also be referred to as “intra-cycle” transfers of heat) between the first compressed fluid flow36, at a mid-pressure with an atmospheric stream of the ram air intake fluid flow80and between a further compressed fluid flow, a second compressed fluid flow82, at an outlet of the ACM compressor68. In the first instance, the first compressed fluid flow36is circulated in heat exchange relationship with the ram air intake fluid flow80to cool the first compressed fluid flow36and generate a first cooled compressed fluid flow78. In the second instance, a second compressed fluid flow82discharged from the compressor68, is circulated in heat exchange relationship with the ram air intake fluid flow80to further cool the second compressed fluid flow82and generate a second cooled compressed fluid flow84. This exchange of heat serves to cool or otherwise decrease the enthalpy of the first compressed fluid flow36, so that the second cooled compressed fluid flow84may then undergo an expansion in the ACM turbine72prior to being discharged from the ACM64, having passed through the condenser74, as a conditioned fluid flow76. The conditioned fluid flow76is next provided to a mixing duct86for subsequent flow into the aircraft cabin or cockpit88.

Referring now toFIG. 3, illustrated is operation of the energy management system40in a flight partial cooling mode. It should be understood that the overall architecture of the energy management system40remains the same as previously described with respect toFIG. 2, yet able to operate in a different operating mode dependent upon utilized components. More specifically, during the illustrated flight partial cooling mode, power is provided by the engine12and thus the means for providing ground power16, and more particularly the APU60, is shown in shadow. In contrast to the previous ground mode of operation, a fan bleed flow entering the CAC14is obtained from the engine fan20as fan discharge fluid flow34. The fan discharge fluid flow34is directed toward the CAC14via inlet duct35and compressed by a compressor62of CAC14, generating a compressed fluid flow36that is directed to the ECS18system via duct37.

As illustrated, the inlet duct35is coupled between an inlet of the CAC compressor64and a source of high-pressure, high-temperature engine fan air extracted from the engine fan20. A combined pressure regulating and shut-off valve (PRSOV) (not shown) may be placed in the inlet duct35and operated by an actuator. The shut-off valve is effective to provide the fan discharge fluid flow34to the CAC compressor64at a desired set point pressure, and to shut off the fan discharge fluid flow34completely when desired. Optionally, a combination of separate valve components in series may be used to achieve the same function. Duct37couples the discharge from an exit of the CAC compressor64and the ECS18. As shown inFIG. 3, the duct37is connected to the ECS18by a shut-off valve (SOV)38which is operated by an actuator. In operation, engine fan discharge fluid flow34, at relatively low pressure and temperature, is discharged from the engine fan20and introduced to the CAC compressor64. Work input from the CAC compressor64increases the fan discharge air temperature and pressure. The CAC compressor64discharges the compressed fluid flow36and provides it to the ECS18through the shut-off valve38and duct37.

As previously indicated with respect toFIG. 2, in the illustrated embodiment, ECS18is configured as an air cycle machine (ACM)64. During the flight partial cooling mode, a portion of the compressed fluid flow36enters the ACM64, passing through the primary heat exchanger66, the ACM air compressor68, the secondary heat exchanger70, the turbine72and the condenser74before exiting the ACM64as a conditioned fluid flow76. Similar to ground cooling mode described with respect toFIG. 2, cooling of the compressed fluid flow36is provided in the primary and secondary heat exchangers66,70wherein the compressed fluid flow36is circulatable in heat exchange relationship with a portion of a ram air intake fluid flow80for cooling of the compressed fluid flow36in the ACM64. In addition, a portion of the compressed fluid flow36passes through the ACM64as a high pressure heated fluid flow79where it is mixed with the conditioned fluid flow76in a mixing duct86, prior to delivery to the cabin or cockpit88.

Referring now toFIG. 4, illustrated is operation of the energy management system40in a flight heating mode. It should again be understood that the overall architecture of the energy management system40remains the same as previously described with respect toFIGS. 2 and 3, yet able to operate in a different operating mode dependent upon utilized components. More specifically, during the illustrated flight heating mode, power is provided by the engine12and thus the means for providing ground power16, and more particularly the APU60, is shown in shadow. Similar to the previously described modes of operation, a fan bleed flow entering the CAC14is obtained from the engine fan20as fan discharge fluid flow34. The fan discharge fluid flow34is directed toward the CAC14via duct35and compressed by a compressor62of CAC14, generating a compressed fluid flow36that is directed to the ECS18system via duct37. As previously indicated, in the illustrated embodiment, ECS18is configured as an air cycle machine (ACM)64. During the flight heating mode, the compressed fluid flow36enters the ACM64and passes directly therethrough, bypassing the primary heat exchanger66, the ACM air compressor68, the secondary heat exchanger70, the turbine72and the condenser74, exiting the ACM64as a heated fluid flow79. The heated fluid flow79is thereafter directed to the aircraft cabin or cockpit88.

Referring now toFIGS. 5-7, illustrated is an energy management system100, generally similar to energy management system10ofFIG. 1. In the embodiment illustrated inFIGS. 5-7, the energy management system100, and more particularly an ECS118is configured as an electric vapor cycle system (VCS)102. In an embodiment, the VCS102is powered by a CAC114flow, and more particularly, a compressed fluid flow136via duct137. Depending on air conditioning needs, there are three main operation modes illustrated for the energy management system100to provide conditioned air to the cabin/cockpit188: a ground cooling mode (FIG. 5), a flight cooling mode (FIG. 6), and a flight heating mode (FIG. 7). As with the embodiment described with respect toFIGS. 2-4, it should be understood that heating, partial cooling and cooling modes may be operated during in flight, or on ground, dependent upon configuration and power source (i.e. engine or ground power source). As previously indicated, throughout the drawings, the double solid lines indicate refrigerated airflow and the dashed line indicates heated airflow.

The energy management system100illustrated inFIGS. 5-7includes an engine112, a CAC114, a means for providing ground power116and an ECS118. In addition, illustrated are an optional liquid cooling loop142, a fuel loop144and an oil and lube system146configured in fluid communication with the ECS118. In an embodiment, the liquid cooling loop142is a propylene glycol/water (PGW) liquid cooling loop and may be included to cool a CAC motor controller. The liquid cooling loop142may include a PGW heat exchanger148, a liquid cooled motor drive150, a PGW pump152and a bypass valve154. Additionally, illustrated is a source of fuel156, such as a fuel tank157including at least one fuel pump158, in fluidic communication with a fuel heat exchanger159.

During a ground cooling mode as best illustrated inFIG. 5, power is provided by the means for ground power116, which in this particular embodiment is an APU160, as previously described with respect toFIGS. 1-4. In the illustrated ground cooling mode, the engine112is in an off mode and thus shown in shadow. A ram air165entering the CAC114is obtained from the ram air intake163via an inlet duct165. The ram air165is directed toward the CAC114and compressed by a compressor162of CAC114, generating a compressed fluid flow136to the ECS118system via duct137. As previously indicated, in the illustrated embodiment ECS18is configured as an electric vapor cycle system (VCS)102. During the ground cooling mode, the compressed fluid flow136enters the VCS102, passing through a heat exchanger166and a first evaporator168before exiting the VCS102as a conditioned fluid flow176. Cooling of the compressed fluid flow136is provided in the primary heat exchanger166wherein the compressed fluid flow136is circulatable in heat exchange relationship with a portion of a ram air intake fluid flow180for cooling of the compressed fluid flow136in the VCS102. The heat exchange unit166functions to cool the fan discharge air134in the energy management system100. The conditioned fluid flow176is next provided to a mixing duct186for subsequent flow into the aircraft cabin or cockpit188.

Referring now toFIG. 6, illustrated is operation of the energy management system100in a flight cooling mode. It should be understood that the overall architecture of the energy management system100remains the same as previously described with respect toFIG. 5, yet able to operate in a different operating mode dependent upon utilized components. More specifically, during the illustrated flight cooling mode, power is provided by the engine112and thus the means for providing ground power116, and more particularly an APU160, is shown in shadow. Similar to the previously described mode of operation, a ram air165entering the CAC114is obtained from the ram air intake163via an inlet duct165. The ram air165is directed toward the CAC114and compressed by a compressor162of CAC114, generating a compressed fluid flow136to the ECS118system. As previously indicated, in the illustrated embodiment, ECS118is configured as a VCS102. During the flight cooling mode, the compressed fluid flow136enters the VCS102, passing through a heat exchanger166and a first evaporator168before exiting the VCS102as a conditioned fluid flow176. Cooling of the compressed fluid flow136is provided in the primary heat exchanger166wherein the compressed fluid flow136is circulatable in heat exchange relationship with a portion of a ram air intake fluid flow180for cooling of the compressed fluid flow136in the VCS102. The heat exchange unit166functions to cool the fan discharge air134in the energy management system100. The conditioned fluid flow176is next provided to a mixing duct186for subsequent flow into the aircraft cabin or cockpit188.

Referring now toFIG. 7, illustrated is operation of the energy management system100in a flight heating mode. It should again be understood that the overall architecture of the energy management system100remains the same as previously described with respect toFIGS. 5 and 6, yet able to operate in a different operating mode dependent upon utilized components. More specifically, during the illustrated flight heating mode, power is provided by the engine112and thus the means for providing ground power116, and more particularly the APU160, is shown in shadow. In contrast to the previously described modes of operation and in light of engine operation in flight, a fan bleed flow entering the CAC114is obtained from the engine fan120as fan discharge fluid flow134. The fan discharge fluid flow134is directed toward the CAC114and compressed by a compressor162of CAC114, generating a compressed fluid flow136to the ECS118system. As previously indicated, in the illustrated embodiment, ECS118is configured as a VCS102. During the flight heating mode, the compressed fluid flow136enters the VCS102, and passes directly therethrough, bypassing the heat exchanger166and exiting the VCS102as a conditioned fluid flow179. In an embodiment, a heating element172may be provided to provide additional heat to compressed fluid flow136when indicated. The heated compressed air flow179is next provided to a mixing duct184for subsequent flow into the aircraft cabin or cockpit186.

FIG. 8is a schematic block diagram of a method200of extracting fan discharge air from a gas turbine engine in an energy management system. Generally, the method involves extracting a fan discharge air flow at a first temperature and a first pressure from a fan of the engine, at a step202. Next in step204, the fan discharge air flow is compressed through a cabin air compressor so as to increase its temperature and pressure and discharge a compressed fluid flow at a second temperature and a second pressure. In step206, the compressed fluid flow is passed through an environmental control system mechanically coupled to the cabin air compressor and discharging a conditioned fluid flow. As previously described, the environmental control system is one of a air cycle machine (ACM) or a vapor cycle system (VCS). The system is configured to operate in one of an inflight heating mode, an inflight cooling mode, an inflight partial cooling mode, a ground heating mode, a ground cooling mode and a ground partial cooling mode.

Accordingly, disclosed is an energy management system including a cabin air compressor and an environmental control system configured to intake a fluid flow from an engine fan discharge and cooling air from a variable geometry ram air inlet, resulting in a decrease in overall aircraft weight and reduction in drag. The utilization of the engine fan discharge fluid flow enables a new energy management system that may provide a potential benefit with respect to fuel savings in aircraft employing the system. It will be understood that the previous modes of operation described herein are merely examples of proposed operating conditions. What is significant is the system provides for fresh air intake during a ground mode of operation, and an engine fan discharge air intake during an inflight mode of operation, thereby providing for a low pressure, low temperature interface to an aircraft ECS that is compatible with the temperature limitations and weight limitations of an aircraft, while minimizing the typical drag inefficiencies.

The foregoing has described an energy management system for a gas turbine engine. While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. While the present disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the 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. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the disclosure. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.