Hybrid electric engine including auxiliary compressor

A hybrid electric gas turbine engine system includes a first compressor and an auxiliary compressor. The first compressor is configured to output first compressed air. The auxiliary compressor is configured to operate in parallel with the first compressor to output second compressed air. A controller is configured to selectively activate the first compressor or the auxiliary compressor based on an operating condition of the hybrid electric gas turbine engine system.

BACKGROUND

Exemplary embodiments pertain to the art of gas turbine engines, and in particular to aircraft hybrid electric engines.

Conventional gas turbine engines are typically operated at an idle thrust level during taxiing from a gate to a runway and can remain at idle thrust for a substantial period of time before takeoff, which consumes a quantity of fuel prior to flight. Hybrid electric aircraft use electricity to provide a portion of the thrust needed for aircraft propulsion by converting electricity into a propulsive force. A hybrid electric aircraft can use an electric drive system (e.g., a battery system and electric motor) to support thrust generation for taxiing operations on a runway and to prevent fuel burn typical of conventional gas turbine engine idling.

BRIEF DESCRIPTION

According to a non-limiting embodiment, a hybrid electric gas turbine engine system includes a first compressor and an auxiliary compressor. The first compressor is configured to output first compressed air. The auxiliary compressor is configured to operate in parallel with the first compressor to output second compressed air. A controller is configured to selectively activate the first compressor or the auxiliary compressor based on an operating condition of the hybrid electric gas turbine engine system.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein in response to detecting a normal operating condition of the hybrid electric gas turbine engine system the controller deactivates the auxiliary compressor and activates the first compressor to output the first compressed air, and wherein in response to detecting an idle operating condition of the hybrid electric gas turbine engine system the controller deactivates the first compressor and activates the auxiliary compressor to output the second compressed air.

According to non-limiting embodiments, the hybrid electric gas turbine engine further comprises a gas-powered turbine configured to generate a first driving force that drives the first compressor to produce the first compressed air; an electric motor configured to generate a second driving force that drives the auxiliary compressor to produce the second compressed air; and a combustor in fluid communication with the first compressor and the auxiliary compressor, the combustor configured to combust one or both of the first compressed air and the second compressed air.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the first compressor includes a low pressure section and a high pressure section, and wherein the at least a portion that is deactivated includes one of the low pressure section or the high pressure section.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the least a portion of the first compressor that is deactivated is prevented from delivering compressed air to the combustor.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the least a portion of the primary compressor that is deactivated is the entire first compressor.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the least a portion of the first compressor that is deactivated is the high pressure section.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the least a portion of the first compressor that is deactivated is the low pressure section.

According to non-limiting embodiments, the hybrid electric gas turbine engine further comprises a clutch configured to selectively engage and disengage the at least a portion of the first compressor from the first driving force, wherein the controller controls the clutch to disengage the at least a portion of the first compressor in response to detecting the idle condition so as to deactivate the least a portion of the first compressor.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the main compressor and the auxiliary compressor operate at the same time, and the contributions of the first compressor and the auxiliary compressor are controlled independently from one another to achieve a targeted fuel consumption during an idle operating condition of the hybrid electric gas turbine engine system.

According to non-limiting embodiments, the hybrid electric gas turbine engine further comprises a first valve including a first inlet in fluid communication with an output of the first compressor and a first outlet in fluid communication with an input of the combustor; and a second valve including a second inlet in fluid communication with an output of the auxiliary compressor and a second outlet in fluid communication with each of the first outlet of the first valve and the input of the combustor, wherein the controller closes the first valve in response to detecting the idle condition so as to block the first compressed air from reaching the combustor.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features wherein the first compressor includes a guide vane configured to selectively operate in an open position and a closed position, and wherein the controller adjusts the guide vane into the closed position in response to detecting the idle condition so as to deactivate the at least a portion of the first compressor.

According to non-limiting embodiments, the hybrid electric gas turbine engine further comprises a battery system configured to deliver power to the electric motor and induces the second driving force.

According to non-limiting embodiments, the hybrid electric gas turbine engine further comprises a generator rotatably coupled to the gas-powered turbine via a shaft assembly to receive the first driving force, and in response to receiving the first driving force generates power that powers to the electric motor and induces the second driving force.

According to non-limiting embodiments, the hybrid electric gas turbine engine system provides additional features, wherein the controller is configured to detect a normal operating condition of the hybrid electric gas turbine engine system, and in response to detecting the normal condition the controller deactivates the auxiliary compressor and activates the first compressor.

According to a non-limiting embodiment, a method of controlling an electric gas turbine engine system is provided. The method comprises operating the electric gas turbine engine system according to a current operating condition among a plurality of different available operating conditions, and selectively controlling, via a controller, a first compressor and an auxiliary compressor configured to operate in parallel with the first controller based on the hybrid electric gas turbine engine system.

According to non-limiting embodiments, the method further comprises activating, via the controller, the first controller to output first compressed air therefrom in response to detecting the current operating condition is a normal operating condition; and deactivating, via the controller, the auxiliary compressor to block output therefrom of a second compressed air.

According to non-limiting embodiments, the method further comprises delivering the first compressed air to a combustor; and combusting the first compressed air using the combustor.

According to non-limiting embodiments, the method further comprises activating, via the controller, the auxiliary controller to output second compressed air therefrom in response to detecting the current operating condition is an idle operating condition; and deactivating, via the controller, at least a portion of the first compressor to block at least a portion of the first compressed air.

According to non-limiting embodiments, the method further comprises delivering the second compressed air to the combustor; and combusting the second compressed air using the combustor.

DETAILED DESCRIPTION

During aircraft idle conditions such as flight idle and ground idle, for example, engine speed, temperatures, pressures and component efficiencies are much smaller than the values found during high-power operating conditions such as, for example, take-off and climbing events. For example, during idle conditions (e.g., during both ground idle and flight idle), conventional aircraft engine systems realize reduced compressor efficiency requiring an increased amount of fuel to be burned to overcome compression losses. During ground idle conditions in particular, the compressor efficiency is typically about 70%, compared to high-power operations where the compressor operates at an efficiency of about 90%.

Various non-limiting embodiments described herein provide an aircraft hybrid electric gas turbine engine system that improves compressor operating efficiency during idle conditions. The hybrid electric gas turbine engine system described herein implements a main compressor and a smaller auxiliary compressor. The auxiliary compressor is preferably configured to operate primarily during idle conditions. During idle conditions, the main compressor or a section of the main compressor (e.g., a low pressure section or a high pressure section) can be switched off (e.g., disconnected) and an electric motor can be switched on to drive the auxiliary compressor. In some embodiments, the main compressor and the auxiliary compressor can be operating at the same time, and the contributions of primary compressor and the auxiliary compressor are controlled independently from one another to achieve targeted fuel consumption during idle conditions. In either scenario, for example, the auxiliary compressor can then provide air to the engine during idle conditions without needing to expend all the fuel that would normally be used to drive the main compressor, or in some embodiments a lower amount of fuel is needed because only a section of the main compressor is being utilized. The air provided by the auxiliary compressor is then combusted with a smaller amount of fuel such that the main turbine provides power to the aircraft generator while realizing improved compressor efficiency during idle conditions.

While the example ofFIG.1illustrates one example of the gas turbine engine20, it will be understood that any number of spools, inclusion or omission of the gear system48, and/or other elements and subsystems are contemplated. Further, rotor systems described herein can be used in a variety of applications and need not be limited to gas turbine engines for aircraft applications. For example, rotor systems can be included in power generation systems, which may be ground-based as a fixed position or mobile system, and other such applications.

Turning now toFIG.2, a hybrid electric gas turbine engine system100including a hybrid electric gas turbine engine200is illustrated according to a non-limiting embodiment. The hybrid electric gas turbine engine200can be similar to the hybrid electric gas turbine engine20illustrated inFIG.1. Therefore, some details of the hybrid electric gas turbine engine200will not be repeated for the sake of brevity.

The hybrid electric gas turbine engine200includes a primary compressor102, a combustor105, and a turbine108. The primary compressor102and the turbine108are each rotatably coupled to a shaft assembly202. The shaft assembly202is configured to rotate, allowing the turbine108to provide a driving torque to the primary compressor102. The combustor105includes an input that is in fluid communication with the primary compressor102and an output that is in fluid communication with the turbine108.-Pressurized air (e.g., from a bleed air source) is available at the exit of the primary compressor102. The compressed air output from the primary compressor102is mixed and burned with fuel in combustor105, and then expanded over the turbine108.

In one or more non-limited embodiments, the primary compressor102includes one or more inlet guide vanes103that can be selectively opened and closed. When open, the primary compressor102is effectively activated and air can be drawn into the primary compressor102and compressed as described herein. When closed, however, air flow into the primary compressor is substantially blocked, or in some instances blocked completely. Accordingly, the primary compressor102is effectively deactivated, or at least partially deactivated.

The hybrid electric gas turbine engine system100further includes a generator120, an auxiliary compressor130, a controller140, and an electric motor150. The generator120is configured to supply electrical energy for electrical loads122of the aircraft. The electrical loads122may include, but are not limited to, electronics, engine and/or aircraft sensors, climate control systems, electric motors, lighting systems, gas turbine engine100support systems, weapon and/or detection systems (e.g., radar), etc.

The auxiliary compressor130is rotatably coupled to the electric motor150via a motor shaft and is in fluid communication with the combustor105. In one or more non-limited embodiments, the auxiliary compressor130can be sized for smaller airflow than the primary compressor102and can be selectively activated when the hybrid electric gas turbine engine200operates in idle conditions. When, for example, the hybrid electric gas turbine engine200operates in an idle condition, electric power152can be delivered to the electric motor150to induce rotation of motor shaft. The electric power152can be provided by various power sources such as, for example, a battery system154. Accordingly, the rotation of the motor shaft provides a driving force that initiates operation of the auxiliary compressor130allowing compression of air input thereto. It should be appreciated that although a battery system154is described as the power source inFIG.2, a different power source such as a generator, for example, may be utilized to power the electric motor150without departing from the scope of the present disclosure. It should be further appreciated that the auxiliary compressor130can be designed and optimized for less airflow and less pressure rise than the primary compressor102, since the auxiliary compressor is only intended to operate at a low-power or idle condition. As a result, the auxiliary compressor130can be designed and optimized for high compressor efficiency at low power or idle conditions, thus enabling higher engine efficiency and lower fuel burn at idle. For example, the auxiliary compressor130could be designed for a maximum airflow that is less than 50%, or even less than 25%, of the primary compressor102maximum airflow, and the auxiliary compressor130could also be designed for a maximum pressure rise (as measured by pressure ratio) that is less than 50%, or even less than 25%, of the primary compressor102maximum pressure rise (as measured by pressure ratio).

In one or more non-limited embodiments, the auxiliary compressor130includes one or more auxiliary inlet guide vanes132that can be selectively opened and closed. When the auxiliary inlet guide vane(s)132are open, the auxiliary compressor130can be activated such that air can be drawn into the auxiliary compressor130and compressed therein. The output compressed air is mixed and burned with fuel in the combustor105, and then expanded over turbine108. When closed, however, air flow into the primary compressor is substantially blocked, or in some instances is blocked completely. Accordingly, the auxiliary compressor130is effectively deactivated.

In one or more non-limiting embodiments, the hybrid electric gas turbine engine system100further includes one or more valves (sometimes referred to as blocker assemblies) in signal communication with the controller140. A given valve can selectively operate in an open position or a closed position in response to a control signal output from the controller140. As shown inFIG.2, for example, the hybrid electric gas turbine engine system100includes a first valve includes204and a second valve206. The first valve204has an inlet in fluid communication with the output of the primary compressor102and an outlet in fluid communication with the inlet of the combustor105. The second valve206has an inlet in fluid communication with the output of the auxiliary compressor130and an outlet in fluid communication with both the outlet of the first valve204and the input of the combustor105.

When the first valve204is open and the second valve206is closed, compressed air output from the primary compressor102is delivered to the combustor105while being blocked from flowing to the auxiliary compressor130. Accordingly, the primary compressor102is effectively activated or at least partially activated. When the first valve204is closed and the second valve206is open, compressed air output from the primary compressor102is blocked from reaching combustor105and the auxiliary compressor130. Accordingly, the primary compressor102is effectively deactivated. However, compressed air output from the auxiliary compressor130can be delivered to the combustor105via the open second valve206.

In one or more non-limiting embodiments, the hybrid electric gas turbine engine system100can further include a transmission208couple to the shaft assembly202, and located between the primary compressor102and the turbine108. The transmission208can include a clutch configured to selectively engage and disengage the rotation of the primary compressor102with the shaft assembly202. When the primary compressor102is rotatably engaged with the shaft assembly202, it rotates along with the shaft assembly202and is effectively activated. When, however, the primary compressor102is rotatably disengaged with the shaft assembly202, the shaft assembly202is allowed to rotate without rotating the primary compressor102. Accordingly, the primary compressor102is effectively deactivated.

When the gas turbine engine200transitions into an idle condition, for example, the controller140can control and operate various valves, inlet guides, gearboxes/clutches included in the hybrid electric gas turbine engine system100to selectively activate and deactivate the primary compressor102(or sections thereof) and/or the auxiliary compressor130. With reference to the example illustrated inFIG.2, the controller140can control the inlet guide vane(s)103, actuator vane(s)132the first and second valves204,206, the transmission208, or any combination of the aforementioned components to selectively deactivate the primary compressor102as described herein. In addition, the electric power152is generated and powers the electric motor150to induce rotation of the motor shaft, which in turn activates and drives the auxiliary compressor130. The compressed air output by the auxiliary compressor130is delivered to the combustor105, thereby driving the turbine108to provide power to the generator120while the primary compressor102is deactivated. In this manner, overall engine compressor efficiency is improved while the engine200operates in the idle condition due to the reduced fuel consumption realized by deactivating the primary compressor102and using the more efficient auxiliary compressor.

Turning now toFIG.3, the hybrid electric gas turbine engine system200is illustrated according to another non-limiting embodiment. In this example, the primary compressor102is implemented as a split compressor102, while the turbine108is implemented as a split turbine108. The primary compressor102includes a low pressure compressor section104and a high pressure compressor section106. Similarly, the turbine108includes a low pressure turbine section110and a high pressure compressor section112. The split architecture of the primary compressor102allows pressurized air to exit from the low pressure compressor section104and be delivered to the auxiliary compressor130, while the pressurized air bypasses the high pressure compressor section106.

In the example illustrated inFIG.3, the auxiliary compressor130is still driven by an electric motor150, which can be powered by various power sources including, but not limited to, a battery or a generator. Accordingly, the split architecture of the primary compressor102illustrated inFIG.3may utilize only a portion (e.g., the low pressure section104) of the primary compressor102, thereby reducing fuel consumption. In this manner, overall engine compressor efficiency is improved during idle conditions.

With reference toFIG.4, the hybrid electric gas turbine engine system200is illustrated according to yet another non-limiting embodiment. The hybrid electric gas turbine engine system200illustrated inFIG.4has a similar architecture to the hybrid electric gas turbine engine system200illustrated inFIG.3. Therefore, some details of the hybrid electric gas turbine engine200will not be repeated for the sake of brevity. In this example, however, the electric motor150is powered by a electric power152output from the generator120. The architectures illustrated inFIGS.2,3, and4allow for controlling the speed of the auxiliary compressor130independently of the speed of the high speed spool32without requiring a variable transmission. Powering the auxiliary compressor130using the generator120, as shown inFIG.4, allows this independent speed control without requiring an external power source such as a battery (with its associated weight and cost) since all compressor drive power can come from the turbine via the generator.

Turning toFIG.5, the hybrid electric gas turbine engine system200is illustrated according to still another non-limiting embodiment. The hybrid electric gas turbine engine system200illustrated inFIG.5also has a similar architecture to the hybrid electric gas turbine engine system200illustrated inFIG.3. In this example, however, the low pressure section104of the primary compressor102is bypassed, while the high pressure section106receives air from the auxiliary compressor130and provides further compression prior to combustion.

According to a non-limiting embodiment, the hybrid electric gas turbine engine system200includes a transmission500and a valve502. The transmission500includes a clutch that As described herein, the controller140can determine whether the hybrid electric gas turbine engine200is operating in above-idle conditions or idle conditions and control the transmission500and/or the valve502accordingly.

The transmission500is located between the low pressure section104and the high pressure section106, and includes a clutch that is configured to selectively engage and disengage the rotation of the low pressure section104with the shaft assembly202. When the low pressure section104is rotatably engaged with the shaft assembly202(e.g. during normal operating conditions), it rotates along with the shaft assembly202and is effectively activated. Accordingly, airflow input to the low-pressure section104undergoes a first compression and the compressed output air is delivered to the high pressure section106to undergo increased compression before being delivered to the combustor105.

When engine idle conditions are detected, the controller140commands the transmission500to disengage the low pressure section104from the shaft assembly202via the clutch. Accordingly, the shaft assembly202is allowed to rotate and drive the high pressure section without rotating the low pressure section104. In this manner, the low pressure section104is effectively deactivated while the high-pressure section106remains activated.

The valve502is located between the output of the auxiliary compressor130and the input of the high pressure compressor106, and is configured to selectively operate in an open position and a closed position. During normal engine operating conditions, the valve502can be closed to block the air flow path between the auxiliary compressor130and the high pressure section106.

When engine idle conditions are detected, however, the valve502can be opened to facilitate air flow between the auxiliary compressor130and the high pressure section106. In addition, when engine idle conditions are detected the electric power152can be delivered to the electric motor150to induce rotation of motor shaft. As described herein, the electric power152can be provided by various power sources including, but not limited to, a battery and a generator (e.g., generator120). The rotation of the motor shaft initiates operation of the auxiliary compressor130. Accordingly, air input to the auxiliary compressor is compressed and the compressed output air is delivered to the high pressure section106, where the air compression is increased before being output to the combustor105. Accordingly, only the high pressure section106of the primary compressor102may be utilized. In this manner, fuel consumption is reduced and overall engine compressor efficiency is improved during idle conditions.

In one or more non-limiting embodiments, the high pressure section106can include one or more high pressure vanes504. When the hybrid electric gas turbine engine200operates during an idle condition, the controller140can close the high pressure vane(s)504. In this manner, the compressed air provided by the auxiliary compressor130is prevented from exiting the inlet of the high pressure section106, thereby improving the compression efficiency of the high pressure section106.