Patent Application
20220412268
Exemplary embodiments of the present disclosure pertain to the art of gas turbine engines, and to aircraft utilizing such engines.
A traditional gas turbine engine utilizes fuel which is combusted with compressed air to drive a turbine. The turbine, in turn, drives rotation of a compressor which supplies the compressed air to the combustor. Other engines are hybrid electric gas turbine engines, which can be selectably powered by electric power from, for example a battery, or by the fuel. During certain operational stages or under certain conditions, such as taxi or cruise operation, powering the engine via electrical power may be more efficient than power via the fuel, while during other operational stages, such as takeoff or climb, operation of the engine via liquid fuel may be more efficient or practical. In addition, electrical power can be used at the same time as the liquid fuel to help drive rotation of the compressor. This may be advantageous when it is desired to increase engine airflow and power more rapidly than can be achieved with fuel alone.
In one embodiment, a hybrid electric engine of an aircraft includes a compressor, a turbine operably connected to the compressor via a variable gear ratio gearbox and a combustor configured to drive the turbine via a flow of combustion products. An electric motor is operably connected to the variable gear ratio rear box and configured to input rotational energy into the gearbox. The input of rotational energy into the gearbox from the electric motor changes a rotational speed of one of the compressor or the turbine relative to the other of the compressor or the turbine.
Additionally or alternatively, in this or other embodiments the input of rotational energy accelerates the compressor relative to the turbine.
Additionally or alternatively, in this or other embodiments the input of rotational energy decelerates the compressor relative to the turbine.
Additionally or alternatively, in this or other embodiments the gearbox is located at a central longitudinal axis of the engine.
Additionally or alternatively, in this or other embodiments the gearbox is located axially forward of the compressor.
Additionally or alternatively, in this or other embodiments the gearbox is located axially between the compressor and the turbine.
Additionally or alternatively, in this or other embodiments the gearbox is located remotely from the engine central longitudinal axis.
Additionally or alternatively, in this or other embodiments in the gearbox includes a planetary gear arrangement.
Additionally or alternatively, in this or other embodiments the electric motor is a variable speed electric motor.
Additionally or alternatively, in this or other embodiments the engine is a two-spool engine configuration, and the compressor is a high pressure compressor and the turbine is a high pressure turbine.
In another embodiment, a method of operating a hybrid electric engine includes combusting a fuel at a combustor, driving a rotation of a turbine via products of the combustion, and driving rotation of a compressor via rotation of the turbine. The turbine and the compressor are operably connected to a variable ratio gearbox. Rotational energy is input from an electric motor into the gearbox and a rotational speed of one of the compressor or the turbine relative to the other of the compressor or the turbine is changed via the input of rotational energy into the gearbox.
Additionally or alternatively, in this or other embodiments the compressor is accelerated relative to the turbine by the input of rotational energy.
Additionally or alternatively, in this or other embodiments the rotational speed of the compressor is increased by up to about 30%.
Additionally or alternatively, in this or other embodiments the compressor is decelerated relative to the turbine by the input of rotational energy.
Additionally or alternatively, in this or other embodiments a default speed ratio of the compressor to the turbine without input of rotational energy from the electric motor is other than 1:1.
Additionally or alternatively, in this or other embodiments a speed of the electric motor is varied.
Additionally or alternatively, in this or other embodiments the rotational energy is transmitted from the electric motor to the gearbox via a tower shaft.
Additionally or alternatively, in this or other embodiments the gearbox is located axially forward of the compressor.
Additionally or alternatively, in this or other embodiments the gearbox is located axially between the compressor and the turbine.
Additionally or alternatively, in this or other embodiments the gearbox is located remotely from the engine central longitudinal axis.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
The exemplary engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure. The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The high speed spool 32 includes an arrangement that interconnects a high pressure compressor 52 and high pressure turbine 54. A combustor 56 is arranged in exemplary engine 20 between the high pressure compressor 52 and the high pressure turbine 54. In one mode of operation, the core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, then expanded over the high pressure turbine 54 and low pressure turbine 46. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion.
Referring now to
The electric motor 66 may provide acceleration of any suitable speed, but in some embodiments a rotational speed of the high pressure compressor 52 is within about +1-30% of a rotational speed of the high speed turbine 54. In some embodiments, when no electrical power is applied, the gearbox outputs a ratio of 1:1, meaning that without the application of electrical power the rotational speed of the high pressure compressor 52 equals the rotational speed of the high speed turbine 54. In other embodiments, this default gear ratio may be other than 1:1. While in some embodiments, the electric motor 66 is utilized to accelerate the high pressure compressor 52, the electric motor 66 may also be an electric machine that can be utilized as a generator to brake or decelerate the high pressure compressor, for example to reduce aerodynamic loading on the compressor blades and aid in stall prevention or initial stall recovery. In some embodiments, the electric motor 66 is a variable speed motor such that additional variability of the relative speed of the high pressure compressor 52 and the high speed turbine 54 may be achieved by varying the speed of the electric motor 66. In some embodiments, it is desired to actively control a relative speed of the compressor shaft 62 and the turbine shaft 60. As such, a compressor speed sensor 82 may be used to detect a compressor shaft speed, and a turbine speed sensor 84 may be used to detect a turbine shaft speed. The speed sensors 82, 84 are connected to a controller 86, which is also connected to the electric motor 66. The detected compressor shaft speed and turbine shaft speed are compared to a desired compressor shaft speed and turbine speed or compared to a desired speed ratio or the like. If one or more of the measured speeds fall outside of a desired range, the controller 86 directs operation of the electric motor 66 to apply input to the gearbox 64 or stop or change the input of the electric motor 66 to the gearbox 64. Further, the electric motor 66 may include a brake mechanism to prevent unnecessary rotation of the electric motor 66 when its input is not desired or needed at the gearbox 64. Such a brake mechanism may be operated by the controller 86 and prevents overheat of the electric motor 66.
Although the embodiment provided above describes a differential gearbox 64 and electric motor 66 drive on the high speed spool 32 of a gas-turbine engine, the same type of gearbox 64 and electric motor 66 arrangement could advantageously be applied to the low speed spool 30 of a gas-turbine engine, instead of or in addition to the gearbox 64 and electric motor 66 arrangement on the high speed spool 32.
In some embodiments, such as shown in
In some embodiments, such as shown in
While the present disclosure is described in the context of a two-spool engine 10, one skilled in the art will readily appreciate that the configurations disclosed herein may be readily applied to a single spool or other multiple spool engines, such as a three spool engine. The variable gear ratio allows for acceleration of, for example the high pressure compressor 52 relative to the high pressure turbine 54, which improves stall recovery performance. Further, such differential speed operation of the high pressure compressor 52 relative to the high pressure turbine 54 has benefits to the engine 10 in the areas of operability, performance, fuel economy and noise reduction.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular 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 indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or 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 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. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed 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.
