Patent Publication Number: US-2021171212-A1

Title: Hybrid turbine engine with selective electrical module engagement

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to propulsion systems, and more specifically to hybrid propulsions systems including a gas turbine engine and one or more propulsors that may be powered by one or more of the gas turbine engine and a battery. 
     BACKGROUND 
     Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a core including a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Left-over products of the combustion are exhausted out of the turbine and may provide thrust in some applications. 
     The compressor, combustor, and/or turbine of a gas turbine engine may generate heat and noise as a consequence of their normal operation. Heat and noise generated by a gas turbine engine may present a threat to an aircraft powered by the gas turbine engine. For example, anti-aircraft missiles often are configured to train on exhaust heat from a gas turbine engine. Also, noise generated by a gas turbine engine may alert enemy combatants to the presence of an aircraft powered by the gas turbine engine. 
     Further, noise from aircraft powered by a gas turbine engine may disturb persons in the vicinity of airports and other areas where the aircraft might fly at lower altitudes, especially during full power maneuvers such as take-off. 
     Moreover, a gas turbine engine may ingest a large mass of air from atmosphere into the core to support operation of the core. Particles, for example, sand particles, may be entrained in the air and drawn into the core therewith during normal operation, especially in an application where the gas turbine engine is used as a propulsor or power source for a propulsor of an aircraft. Such particles may cause impact damage to elements of the core. Also, such particles may glassify within the core and thereby become adhered to components of the core due to the high temperatures the particles might be exposed to with the core. 
     SUMMARY 
     The present disclosure may comprise one or more of the following features and combinations thereof. 
     A hybrid propulsion system for use with an aircraft may include a gas turbine engine core, an electric power system, at least one propulsor, and a controller. The gas turbine engine core includes a compressor, a combustor, and a turbine. The electric power system may include an energy storage device, a generator connected with the energy storage device, and a motor connected with the energy storage device. The motor is configured to produce rotational energy in response to receiving electric energy from the energy storage device. 
     The at least one propulsor is configured to use energy received from at least one of the gas turbine engine core and the electric power system to generate thrust for propelling the aircraft. The controller is configured to control provision of power from the engine core and the electric power system to the at least one propulsor to cause the at least one propulsor to generate thrust having a force magnitude value and to adjust the provision of power from the engine core and the electric power system in response to the controller receiving a signal so that the at least one propulsor continues to generate thrust having the force magnitude value. 
     In some embodiments, the controller may control the provision of energy by varying at least one of a rotational speed of the engine core and a fuel flow into the engine core while simultaneously varying the provision of power from the electric power system to the at least one propulsor. 
     In some embodiments, the signal may be generated in response to a manual input provided by a user of the hybrid propulsion system. In some embodiments, the signal may be generated in response to the controller detecting a threat to the aircraft. 
     In some embodiments, the system may include a particle sensor connected with the controller and located at an inlet of the gas turbine engine core. The signal may be generated in response to the sensor detecting a number of particles suspended in air entering the inlet being greater than a predetermined threshold value. 
     In some embodiments, the controller may reduce the rotational speed of the gas turbine engine core in response to receiving the signal to cause the number of particles entering the gas turbine engine core to be reduced. In some embodiments, the controller may reduce the fuel flow into the gas turbine engine core in response to receiving the signal to reduce a temperature of gases in the gas turbine engine core to lower the number of particles being glassified in the gas turbine engine core. 
     In some embodiments, the controller may be configured to limit at least one of a rotational speed of the gas turbine engine core and a fuel flow into the gas turbine engine core during take-off of the aircraft. The controller may be configured to increase the at least one of a rotational speed of the gas turbine engine core and fuel flow into the gas turbine engine core during at least one of climb and cruise of the aircraft to reduce a number of particles suspended in airflow entering the gas turbine engine core during take-off. 
     In some embodiments, the signal may be generated in response to a noise level generated by the hybrid propulsion system being above a predetermined noise threshold. In some embodiments, the signal may be generated in response to an altitude of the aircraft being less than a predetermined altitude limit. 
     In some embodiments, the controller may be configured to detect a geographical location of the aircraft. The signal may be generated in response to the geographical location of the aircraft the hybrid propulsion system being within a preset zone. In some embodiments, the preset zone may be associated with a predetermined airport location. 
     In some embodiments, the controller may be configured to reduce a rotational speed of the gas turbine engine core to reduce noise generated by the hybrid propulsion system in response to receiving the signal. In some embodiments, the controller may be configured to reduce fuel flow to the gas turbine engine core to reduce an amount of heat generated by the hybrid propulsion system in response to receiving the signal. 
     In some embodiments, the hybrid propulsion system may include a sensor connected with the controller. The sensor may be configured to detect an exhaust temperature of the gas turbine engine core. The controller may be configured to generate the signal based on data received from the sensor to control a power output of the gas turbine engine core to maintain the exhaust temperature at or below a predetermined level. 
     In some embodiments, the at least one propulsor may include at least one of a turbofan coupled directly with the gas turbine engine core, a fan located remote from the gas turbine engine core, and a propeller. In some embodiments, the electric power system may be coupled with the gas turbine engine core. The electric power system may be configured to rotate the gas turbine engine core to provide power to the at least one propulsor via the gas turbine engine core. 
     According to another aspect of the present disclosure, a method of operating a hybrid propulsion system may comprise a number of steps. The method may include providing a gas turbine engine core including a compressor, a combustor, and a turbine; providing an energy storage device; providing at least one propulsor configured to use energy received from at least one of the gas turbine energy and the energy storage device to generate thrust for propelling an aircraft; and varying a provision of power between the gas turbine engine core and the energy storage device to the propulsion system in response to a signal so that the at least one propulsor achieves a predetermined thrust level. 
     In some embodiments, the step of varying may comprise varying at least one of a rotational speed of the gas turbine engine core and a fuel flow into the gas turbine engine core. In some embodiments, the signal may be provided by a sensor to a controller and the controller may be configured to perform the step of varying. 
     These and other features of the present disclosure will become more apparent from the following description of the illustrative embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a diagrammatic view of a first embodiment of a hybrid propulsion system for use with an aircraft according to the present disclosure, the hybrid propulsion system including a gas turbine engine core; an electric power system having a battery, two motors powering corresponding propulsors, and a generator configured to power the motors and charge the battery; and a controller configured to regulate fuel provided to the gas turbine engine core and electrical energy provided to the motors by the generator and the battery; 
         FIG. 1B  is a physical illustration view of the hybrid propulsion system of  FIG. 1A ; 
         FIG. 2A  is a diagrammatic view of another embodiment of a hybrid propulsion system according to the present disclosure, the hybrid propulsion system including a gas turbine engine core; a propulsor powered by the gas turbine engine core; an electric power system having a battery, a motor-generator configured to use electric energy from the battery to further power the propulsor via a turbine shaft of the gas turbine engine and to charge the battery; and a controller configured to regulate fuel provided to the gas turbine engine core and electrical energy provided to the motor-generator by the battery; 
         FIG. 2B  is a physical illustration view of the hybrid propulsion system of  FIG. 2A ; 
         FIG. 3B  is a diagrammatic view of another embodiment of a hybrid propulsion system according to the present disclosure, the hybrid propulsion system including a gas turbine engine core; a propulsor powered by the gas turbine engine core; an electric power system having a battery, a motor-generator configured to use electric energy from the battery to further power the propulsor via a gear box and to charge the battery; and a controller configured to regulate fuel provided to the gas turbine engine core and electrical energy provided to the motor by the battery; 
         FIG. 3B  is a physical illustration view of the hybrid propulsion system of  FIG. 3A ; 
         FIG. 4A  is a diagrammatic view of another embodiment of a hybrid propulsion system according to the present disclosure, the hybrid propulsion system including a gas turbine engine core; a first propulsor powered by the gas turbine engine core; an electric power system having a battery, two motors powering corresponding second propulsors, a motor-generator configured to use electric energy from the battery to further power the first propulsor via a turbine shaft of the gas turbine engine, to power the motors of the second propulsors, and to charge the battery; and a controller configured to regulate fuel provided to the gas turbine engine core and electrical energy provided to the motor-generator and the motors of the second propulsors; and 
         FIG. 4B  is a physical illustration view of the hybrid propulsion system of  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments illustrated in the drawings and specific language will be used to describe the same. 
       FIGS. 1A and 1B  are, respectively, diagrammatic and physical illustration views of a first embodiment of a hybrid propulsion system  10  for use with an aircraft according to the present disclosure. The hybrid propulsion system  10  includes a gas turbine engine core  12 , an electric power system  14 , and a controller  16 . The gas turbine engine core  12  includes a compressor  18 , a combustor  20 , and a turbine  22 . The combustor  20  is configured to receive fuel F from a fuel source  24 . 
     As shown in  FIGS. 1A and 1B , the electric power system  14  includes a generator  26  operably connected to the gas turbine engine core  12  by an output shaft  28 , an electric motor  30 , a propulsor  32  powered by the motor  30 , and an energy storage device  34  such as a battery  34 . The propulsor  32  may be for example, a fan or a propeller. The generator  26 , motor  30 , and battery  34  are operably connected to each other. The operable connection between the generator  26 , motor  30 , and battery  34  allows the generator  26  to selectively provide power to the motor  30  to drive the motor  30  and to selectively provide power to the battery  34  to charge the battery  34 . The operable connection between the generator  26 , motor  30 , and battery  34  also allows the battery  34  to selectively provide power to the motor  30  to drive the motor  30 , and to selectively receive power from the generator  26  to charge the battery  34 . 
     As shown in  FIG. 1B , the electric power system  14  may further include a second motor  30  and second propulsor  32  powered by the second motor  30 . In other embodiments, the electric power system  14  could include more than two motors  30  and propulsors  32  powered by respective ones of the motors  30 . References herein to the motor  30  and propulsor  32  powered by the motor  30  should be construed to apply similarly to plural motors  30  and propulsors  32  powered by respective ones of the motors  30  in embodiments having plural motors  30  and propulsors  32  powered by respective ones of the motors  30 . 
     The controller  16  is configured to control the relative amounts of power provided to the motor  30  from the generator  26  and the battery  34  so that the motor  30  provides an amount of torque to the propulsor  32  to achieve a thrust having a desired force magnitude value. The controller  16  may cause a first portion of the power to be provided to the motor  30  by the generator  26  and a second portion of the power provided to the motor  30  to be provided by the battery  34 . 
     The first portion of the power may be any value ranging from 0% to 100% of the power required to achieve the desired force magnitude value, and the second portion of the power may be any complementary value ranging from 100% to 0% of the power required to achieve the desired force magnitude value. As such, the sum of the first portion of the power and the second portion of the power equals 100% of the power required to achieve the desired force magnitude value. 
     During operation, the hybrid propulsion system  10  provides a first thrust with a first force magnitude value as achieved through a first power split between the gas turbine engine core  12  and the battery  34 . (For example, 100% power from the gas turbine engine core  12  and generator  26 .) The controller  16  is configured to receive an input to cause the controller  16  to generate instructions to vary the amount of power provided by each of the gas turbine engine core  12  (via generator  26 ) and the battery  34  as described in detail below to achieve the thrust having the desired force magnitude value. (For example, the controller  16  could vary the split from 100% to 50% power from the gas turbine engine core  12  and from 0% to 50% power from the battery  34 .) The desired force magnitude value is greater than the thrust with a force magnitude value that would be achieved if only the power of the gas turbine engine core  12  was reduced, but no additional power from the battery  34  was supplied. 
     In some embodiments, the desired force magnitude value is about equal to the first force magnitude value of the first thrust such that the thrust does not change in response to the power distribution being varied. In another embodiment, the sum of the first portion of the power and the second portion of the power could be less than or greater than 100% of the power required to achieve the first force magnitude value, so that the actual force magnitude value is less than or greater than the first force magnitude value. In any event, the sum of the first portion of the power and the second portion of the power is greater than the first portion of the power. 
     The controller  16  is configured to control the relative amounts of power provided to the motor  30  from the generator  26  and the battery  34  in response to a signal S. Based on the signal S (or lack thereof), the controller  16  may vary the relative amounts of power provided to the motor  30  from the generator  26  and the battery  34 . For example, the controller  16  may increase the first portion of the power provided to the motor  30  by the generator  26  and simultaneously decrease the second portion of the power provided to the motor  30  by the battery  34 . Conversely, the controller  16  may decrease the first portion of the power provided to the motor  30  by the generator  26  and simultaneously increase the second portion of the power provided to the motor  30  by the battery  34 . 
     The controller  16  is configured to vary the flow of fuel F to the combustor  20 , thereby varying the power output of the gas turbine engine core  12 , the power output of the generator  26 , and the amount of power provided to the motor  30  from the generator  26 . For example, the controller  16  may increase the flow of fuel F to the combustor  20 , thereby increasing the power output of the gas turbine engine core  12 , the power output of the generator  26 , and the amount of power that may be provided to the motor  30  from the generator  26 . Conversely, the controller  16  may decrease the flow of fuel F to the combustor  20 , thereby decreasing the power output of the gas turbine engine core  12 , the power output of the generator  26  and the amount of power that may be provided to the motor  30  from the generator  26 . 
     The controller  16  is further configured to vary another flow of fuel to the turbine  22  or an afterburner in some embodiments. Discussions of varying the flow of fuel F to the combustor  20  also apply to the controller being able to vary the flow of fuel to other combustion areas of the gas turbine engine core  12  such as the turbine  22  or afterburner. 
     Alternatively or additionally, the controller  16  is configured to vary the rotational speed of the gas turbine engine core  12 , thereby varying the power output of the gas turbine engine core  12 , the power output of the generator  26 , and the amount of power provided to the motor  30  from the generator  26 . For example, the controller  16  may increase the increase the rotational speed of the gas turbine engine core  12 , thereby increasing the power output of the gas turbine engine core  12 , the power output of the generator  26 , and the amount of power that may be provided to the motor  30  from the generator  26 . Conversely, the controller  16  may decrease the rotational speed of the gas turbine engine core  12 , thereby decreasing the power output of the gas turbine engine core  12 , the power output of the generator  26  and the amount of power that may be provided to the motor  30  from the generator  26 . Varying the rotational speed of the gas turbine engine core  12  may be achieved with or without varying the flow of fuel and the flow of fuel may be varied with or without varying the rotational speed of the gas turbine engine core  12 . 
     Varying the flow of fuel F to the combustor  20  may cause a corresponding variation in the heat generated by the gas turbine engine core  12  and the exhaust temperature of the gas turbine engine core  12 . For example, increasing the flow of fuel F to the combustor  20  may cause the heat generated by the gas turbine engine core  12  and the exhaust temperature of the gas turbine engine core  12  to increase, and decreasing the flow of fuel F to the combustor  20  may cause the heat generated by the gas turbine engine core  12  and the exhaust temperature of the gas turbine engine core  12  to decrease. Varying the flow of fuel F to the combustor  20  may vary the amount of noise generated by the gas turbine engine core  12 . 
     Varying the rotational speed of the gas turbine engine core  12  may cause a variation in the air flow through the gas turbine core  12 . For example, increasing the rotational speed of the gas turbine engine core  12  may cause an increase in the air flow through the gas turbine core  12 , and decreasing the rotational speed of the gas turbine engine core  12  may cause a decrease in the air flow through the gas turbine core  12 . Also, increasing the rotational speed of the gas turbine engine core  12  cause an increase in noise generated by the gas turbine engine core, and decreasing the rotational speed of the gas turbine engine core  12  may cause a decrease in noise generated by the gas turbine core  12 . 
     As mentioned above, the controller  16  is configured to control the relative amounts of power provided to the motor  30  from the generator  26  and the battery  34  in response to a signal S. The signal S may be provided manually by a user of the hybrid propulsion system  10 . For example, the user of the hybrid propulsion system  10  may actuate a switch SW or other input device coupled with the controller  16 , thereby providing the signal S to the controller  16 . Alternatively or additionally, the signal S may be provided automatically by one or more sensors SEN. The signal S provided by such a sensor SEN may be indicative of various items of information, as will be discussed further below. 
     The controller  16  is configured to respond to the signal S by reducing the first portion of the power provided to the motor  30  by the generator  26  and simultaneously increasing the second portion of the power provided to the motor  30  by the battery  34 , or vice versa, to achieve thrust provided by the hybrid propulsion system  10  at the desired force magnitude value, as discussed above in some embodiments. For example, the controller  16  may be configured to respond to the signal S by reducing at least one of the flow of fuel F to the gas turbine engine core  12  and the rotational speed of the gas turbine engine core  12 , consequently reducing the first portion of the power provided to the motor  30  by the generator  26  to a level less than that required to achieve the thrust provided by the hybrid propulsion system  10  at the desired force magnitude value. To compensate for the reduction in the first portion of the power provided to the motor  30  by the generator  26 , the controller  16  increases the second portion of the power provided to the motor  30  by the battery  34  to achieve the thrust provided by the hybrid propulsion system  10  at the desired force magnitude value. 
     Similarly, the controller  16  is configured to respond to the absence or clearing of the signal S by increasing at least one of the flow of fuel F to the gas turbine engine core  12  and the rotational speed of the gas turbine engine core  12 , consequently increasing the first portion of the power provided to the motor  30  by the generator  26  to a level sufficient to achieve the thrust provided by the hybrid propulsion system  10  at the desired force magnitude value. To compensate for the increase in the first portion of the power provided to the motor  30  by the generator  26 , the controller decreases the second portion of the power provided to the motor  30  by the battery  34  to achieve the thrust provided by the hybrid propulsion system  10  at the desired force magnitude value. 
     The controller  16  may further be configured to increase the power output of the gas turbine engine core  12  and the generator  26  to a level greater than 100% of the power required by the motor  30  to achieve the thrust provided by the hybrid propulsion system  10  at a desired force magnitude value. Any surplus power so provided may be used to charge the battery  34  or to operate another electrical load. 
     In an embodiment, the signal S provided by the sensor SEN could be indicative of a threat to the aircraft, for example, indicative of an anti-aircraft missile targeting heat generated and exhausted by the gas turbine engine core  12 . The controller  16  may be configured to respond to the signal S by decreasing the flow of fuel F to the combustor  20 , thereby reducing the exhaust temperature of the gas turbine engine core  12 , and thereby mitigating the threat. 
     As discussed above, the reduction in fuel flow may yield a decrease in power output by the gas turbine engine core  12  and a decrease in the power output of the generator  26 . Consequently, the first portion of power provided to the motor  30  by the generator  26  would decrease. In order to achieve the thrust output of the hybrid propulsion system  10  at the desired force magnitude value, the controller  16  would increase the second portion of the power provided to the motor by the battery  34  so that the first portion of the power provided to the motor  30  from the generator  26  plus the second portion of the power provided to the motor  30  from the battery  34  equals 100% of the power required by the motor  30  to achieve the thrust output at the desired force magnitude value. 
     Once the threat has passed, and the signal S indicative of the threat has cleared (or if the energy stored in the battery  34  has been depleted or is nearing depletion), the controller  16  could decrease the second portion of the power and increase the first portion of the power as desired to achieve the desired force magnitude value. For example, the controller  16  could reduce the second portion of the power to as little as 0% of the power needed to achieve the desired force magnitude value and increase the flow of fuel F to the combustor  20 , thereby increasing the power output of the gas turbine engine core  12  sufficiently to enable the generator  26  to provide at least 100% of the power needed by the motor  30  to achieve the thrust of the hybrid propulsion system  10  at the desired force magnitude value. Any power greater than 100% of the power needed by the motor  30  to achieve the thrust of the hybrid propulsion system  10  at the desired force magnitude value could be used to charge the battery  34  or to power another electrical load. 
     In the foregoing embodiment, the controller  16  could be configured to reduce the heat generated by the gas turbine engine core  12  and/or the exhaust temperature of the gas turbine engine core  12  to the greatest extent possible by reducing the first portion of the power provided to the motor  30  by the gas turbine engine core  12  and the generator  26  to the greatest extent possible, while achieving the thrust provided by the hybrid propulsion system at the desired force magnitude value. 
     In an embodiment, the controller  16  could be configured to vary the first portion of the power and the second portion of the power to maintain the exhaust temperature of the gas turbine engine core  12  below a predetermined threshold value as determined by an exhaust temperature sensor (not shown) providing an input to the controller  16 . 
     In an embodiment, the sensor SEN could be a particle sensor configured to generate a signal S indicative of the sensor SEN detecting a number or mass of particles suspended in air entering an inlet of the gas turbine engine core  12  in excess of a first predetermined threshold value. The controller  16  could be configured to respond to the signal S received from the sensor SEN by reducing the rotational speed of the gas turbine engine core  12  and, more specifically, the compressor  18  of the gas turbine engine core  12 , thereby causing the number of mass of particles entering the gas turbine engine core  12  to be reduced. The signal S could be generated by an operator of the aircraft manually inputting the signal due to known high particle conditions such as take off in a sandy or dusty environment. 
     As discussed above, such a reduction in rotational speed of the gas turbine engine core  12  may reduce the power output of the gas turbine engine core  12  and reduce the power output of the generator  26 . Consequently, the first portion of power provided to the motor  30  by the generator  26  would decrease. In order to achieve the thrust output of the hybrid propulsion system  10  at the desired force magnitude value, the controller  16  would increase the second portion of the power provided to the motor by the battery  34  so that the first portion of the power provided to the motor  30  from the generator  26  plus the second portion of the power provided to the motor  30  from the battery  34  equals 100% of the power required by the motor  30  to achieve the thrust output at the desired force magnitude value. 
     Additionally or alternatively, the controller  16  could be configured to respond to the signal S received from the particle sensor by decreasing the fuel flow to the decreasing the flow of fuel F to the combustor  20 , thereby reducing the temperature of the gas turbine engine core  12 , and thereby potentially lowering the number of particles glassified in the gas turbine engine core  12 . As discussed above, the reduction in fuel flow typically would yield a decrease in power output by the gas turbine engine core  12  and a decrease in the power output of the generator  26 . 
     Consequently, the first portion of power provided to the motor  30  by the generator  26  would decrease. In order to achieve the thrust output of the hybrid propulsion system  10  at the desired force magnitude value, the controller  16  would increase the second portion of the power provided to the motor  30  by the battery  34  so that the first portion of the power provided to the motor  30  from the generator  26  plus the second portion of the power provided to the motor  30  from the battery  34  equals 100% of the power required by the motor  30  to achieve the thrust output at the desired force magnitude value. 
     Once the signal S has cleared, for example, because the number or mass of particles entering the inlet of the gas turbine engine core detected by the sensor SEN has fallen below a second predetermined threshold value (which may be lower than the first predetermined threshold value), the controller  16  may decrease the second portion of the power provided to the motor by the battery  34  and increase the first portion of the power provided to the motor  30  from the generator  26 , as discussed above. 
     In an embodiment, the sensor SEN could be a geographical location sensor, for example, a global position system (GPS) unit configured to provide a signal S indicative of the geographical location of the hybrid propulsion system  10 . The controller  16  could be configured to respond to the signal S by consulting a look up table or other database to determine whether noise restrictions are associated with the geographical location. If so, the controller  16  could further be configured to limit noise generated by the gas turbine engine core  12  to no greater than a predetermined threshold value by limiting at least one of the flow of fuel F to the combustor  20  and the rotational speed of the gas turbine engine, and thereby limiting the power output of the gas turbine engine core  12  and the generator  26 . In the event that the resulting power output of the generator  26  is less than required by the motor  30  to achieve a desired force magnitude value, the controller  16  could respond by providing sufficient additional power from the battery  34  to the motor  30  to achieve the desired force magnitude value. 
     The controller  16  could be configured to receive an actual noise level from another sensor (nor shown) located proximate the hybrid propulsion system  10 , for example, on an aircraft embodying the hybrid propulsion system  10 , or on the ground at or near the geographical location. The geographical location may be a predetermined airport location or a predetermined zone which may include or otherwise be associated with a predetermined airport location. Alternatively, the controller  16  could be configured to calculate a theoretical noise level based on the flow of fuel F into the combustor and/or the rotational speed of the gas turbine engine core  12 . The controller  16  could be configured to vary the flow of fuel F to the combustor and/or the rotational speed of the gas turbine engine core  12  so that the actual or theoretical noise level is no greater than the predetermined threshold value. 
     Once the signal S has cleared because the hybrid propulsion system  10  has exited a geographical location having associated noise restrictions, the controller  16  may decrease the second portion of the power provided to the motor by the battery  34  and increase the first portion of the power provided to the motor  30  from the generator  26 , as discussed above. 
     In an embodiment, the sensor SEN could be a geographical location sensor, for example, a global position system (GPS) unit configured to provide a signal S indicative of the geographical location and altitude of the hybrid propulsion system  10 . The geographical location may be a predetermined airport location or a predetermined zone which may include or otherwise be associated with a predetermined airport location. The controller  16  could be configured to respond to the signal S by reducing or limiting at least one of rotational speed of the gas turbine engine core  12  and flow of fuel F to the combustor  20  when the hybrid propulsion system  10  is at or about the geographical location and below the predetermined elevation to reduce noise emanating from the hybrid propulsion system  10  during taxi, takeoff from, and landing at the geographical location. As discussed above, each of reducing the rotational speed of the gas turbine engine core  12  and reducing the flow of fuel F to the combustor  20  may yield a decrease in power output by the gas turbine engine core  12  and a decrease in the power output of the generator  26 . 
     Consequently, the first portion of power provided to the motor  30  by the generator  26  would decrease. In order to achieve the thrust output of the hybrid propulsion system  10  at the desired force magnitude value, the controller  16  would increase the second portion of the power provided to the motor by the battery  34  so that the first portion of the power provided to the motor  30  from the generator  26  plus the second portion of the power equals 100% provided to the motor  30  from the battery  34  equals 100% of the power required by the motor  30  to achieve the thrust output at the desired force magnitude value. 
     Once the signal S has cleared because the hybrid propulsion system has moved away from the geographical location or outside of the predetermined zone or has climbed above the predetermined elevation, the controller  16  the controller  16  may decrease the second portion of the power provided to the motor by the battery  34  and increase the first portion of the power provided to the motor  30  from the generator  26 , as discussed above. 
       FIGS. 2A and 2B  are, respectively, diagrammatic and physical illustration views of a second embodiment of a hybrid propulsion system  110  for use with an aircraft according to the present disclosure. The hybrid propulsion system  110  includes a gas turbine engine core  112 , an electric power system  114 , and a controller  116 . The gas turbine engine core  112  includes a compressor  118 , a combustor  120 , and a turbine  122 . The combustor  120  is configured to receive fuel F from a fuel source  124 . 
     As shown in  FIGS. 2A and 2B , the electric power system  114  includes a generator  126  operably connected to the gas turbine engine core  112  by an output shaft  128 , an electric motor  130 , a propulsor  133  selectively powered by the gas turbine engine core  112  and the motor  130 , and a battery  134 . The propulsor  133  may be, for example, a turbofan or a propeller. The propulsor  133  may be connected to the gas turbine engine core by a propulsor shaft  136 . The propulsor shaft  136  may be operably connected to the output shaft  128 . In an embodiment, the output shaft  128  and the propulsor shaft  136  may be the same shaft. The generator  126 , motor  130 , and battery  134  are operably connected to each other. 
     The generator  126  and motor  130  may be combined into a single unit. The operable connection between the generator  126 , motor  130 , and battery  134  allows the generator  126  to selectively provide power to the motor  130  to drive the motor  130  and to selectively provide power to the battery  134  to charge the battery  134 . The operable connection between the generator  126 , motor  130 , and battery  134  also allows the battery  134  to selectively provide power to the motor  130  to drive the motor  130 , and to selectively receive power from the generator  126  to charge the battery  134 . 
     The controller  116  of  FIGS. 2A and 2B  may be configured to operate the hybrid propulsion system  110  thereof in a manner similar to the manner in which the controller  16  of  FIGS. 1A and 1B  may be configured to operate the hybrid propulsion system  10  thereof. For example, the controller  116  may be configured to vary at least one of a flow of fuel F to the combustor  120  and a rotational speed of the gas turbine engine core  112 , thereby varying a first portion of power provided by the gas turbine engine core  112  to the propulsor  133  via the propulsor shaft  136 , and also to the output shaft  128 . The controller  116  may be configured to simultaneously vary a second portion of power provided by the motor  130  to the propulsor  133  via the propulsor shaft  136  so that the first portion of the power plus the second portion of the power equal 100% of the power required to achieve thrust output of the hybrid propulsion system  110  at a desired force magnitude value. 
     The controller  116  of  FIGS. 2A and 2B  may respond to one or more signals S as described above in connection with the controller  16  of  FIGS. 1A and 1B  to vary the first portion of the power and the second portion of the power provided to the propulsor  133 . 
       FIGS. 3A and 3B  are, respectively, diagrammatic and physical illustration views of a third embodiment of a hybrid propulsion system  210  for use with an aircraft according to the present disclosure. The system  210  includes a gas turbine engine core  212 , an electric power system  214 , and a controller  216 . The gas turbine engine core  212  includes a compressor  218 , a combustor  220 , and a turbine  222 . The combustor  220  is configured to receive fuel F from a fuel source  224 . 
     As shown in  FIGS. 3A and 3B , the electric power system  214  includes a generator  226 , an electric motor  230 , a propulsor  233  selectively powered by the gas turbine engine core  212  and the motor  230 , and a battery  234 . The propulsor  233  may be, for example, a turbofan or a propeller. The propulsor  233  may be connected to the gas turbine engine core  12  by a propulsor shaft  236  through an intervening gearbox  238 . The propulsor shaft  236  also may be operably connected to an auxiliary shaft  228  via the intervening gearbox  238 . The gearbox  238  may be connected to the propulsor  233 . The generator  226 , motor  230 , and battery  234  are operably connected to each other. The generator  226  and motor  230  may be combined into a single unit. 
     The operable connection between the generator  226 , motor  230 , and battery  234  allows the generator  226  to selectively provide power to the motor  230  to drive the motor  230  and to selectively provide power to the battery  234  to charge the battery  234 . The operable connection between the generator  226 , motor  230 , and battery  234  also allows the battery  234  to selectively provide power to the motor  230  to drive the motor  230 , and to selectively receive power from the generator  226  to charge the battery  234 . 
     The controller  216  of  FIGS. 3A and 3B  may be configured to operate the hybrid propulsion system  210  thereof in a manner similar to the manner in which the controller  116  of  FIGS. 2A and 2B  may be configured to operate the hybrid propulsion system  110  thereof. For example, the controller  216  may be configured to vary at least one of a flow of fuel F to the combustor  220  and a rotational speed of the gas turbine engine core  212 , thereby varying a first portion of power provided by the gas turbine engine core  212  to the propulsor  233  via the propulsor shaft  236 . The controller  216  may be configured to simultaneously vary a second portion of power provided by the motor  230  to the propulsor  233  via the auxiliary shaft  228  and the gearbox  238  so that the first portion of the power plus the second portion of the power equal 100% of the power required to achieve thrust output of the hybrid propulsion system  210  at a desired force magnitude value. 
     The controller  216  of  FIGS. 3A and 3B  may respond to one or more signals S as described above in connection with the controller  16  of  FIGS. 1A and 1B  to vary the first portion of the power and the second portion of the power provided to the propulsor  233 . 
       FIGS. 4A and 4B  are, respectively, diagrammatic and physical illustration views of a third embodiment of a hybrid propulsion system  310  for use with an aircraft according to the present disclosure. The system  310  includes a gas turbine engine core  312 , an electric power system  314 , and a controller  316 . 
     As shown in  FIGS. 4A and 4B , the electric power system  314  includes a generator  326  operably connected to the gas turbine engine core  312  by an output shaft  328 , an electric motor  330 , a propulsor  332  powered by the motor  330 , and a battery  334 . The propulsor  332  may be, for example, a fan or a propeller. The generator  326 , motor  330 , and battery  334  are operably connected to each other. 
     The operable connection between the generator  326 , motor  330 , and battery  334  allows the generator  326  to selectively provide power to the motor  330  to drive the motor  330  and to selectively provide power to the battery  334  to charge the battery  334 . The operable connection between the generator  326 , motor  330 , and battery  334  also allows the battery  334  to selectively provide power to the motor  330  to drive the motor  330 , and to selectively receive power from the generator  326  to charge the battery  334 . 
     As shown in  FIG. 4B , the electric power system  314 , the electric power system  314  may further include a second motor  330  and second propulsor  332  powered by the second motor  330 . In other embodiments, the electric power system  314  could include more than two motors  330  and propulsors  332  powered by respective ones of the motors  330 . References herein to the motor  330  and propulsor  332  powered by the motor  330  should be construed to apply similarly to plural motors  330  and propulsors  332  powered by respective ones of the motors  330  in embodiments having plural motors  330  and propulsors  332  powered by respective ones of the motors  330 . 
     The hybrid propulsion system  310  also includes a gas turbine engine-driven propulsor  333  driven exclusively by the gas turbine engine core  312 . The gas turbine engine-driven propulsor  333  is connected to the gas turbine engine core  312  by a propulsor shaft  336 . The gas turbine engine-driven propulsor  333  may be, for example, a turbofan or a propeller. 
     The controller  316  of  FIGS. 4A and 4B  may be configured to operate the hybrid propulsion system  310  thereof in manner similar to that in which the controller  16  of  FIGS. 1A and 1B  may be configured to operate the hybrid propulsion system  10  thereof. For example, the controller  316  may be configured to vary at least one of a flow of fuel F to the combustor  320  and a rotational speed of the gas turbine engine core  312 , thereby varying a first portion of power provided by the gas turbine engine core  312  to the gas turbine engine-driven propulsor  333  via the propulsor shaft  336  and to the generator  326  via the output shaft. The controller  316  may be configured to simultaneously vary a second portion of power provided by the motor  330  to the propulsor  332  so that the first portion of the power plus the second portion of the power equals 100% of the power required to achieve thrust output of the hybrid propulsion system  310  at a desired force magnitude value. 
     The controller  316  of  FIGS. 4A and 4B  may respond to one or more signals S as described above in connection with the controller  16  of  FIGS. 1A and 1B  to vary the first portion of the power provided to the gas turbine engine-driven propulsor  313  and the second portion of the power provided to the propulsor  332  riven by the motor  330 . 
     The present disclosure relates to methods or arrangements that may reduce the size of inlet particle separator (IPS) and/or inlet barrier filter (IBF) systems on an engine. In typical embodiments, IPS or IBF systems may be large, complex, and expensive, and may also adversely affect the performance of the engine. Therefore, there are tradeoffs that may sacrifice engine power, but provide improved particle separation and ingestion prevention (i.e. sand ingestion, ice, volcanic ash, and/or other environmental debris). 
     As such, the present disclosure teaches an electrically augmented engine particle separator system that utilizes a hybrid propulsion system  10 ,  210 .  310  to augment output power of the engine for core mass airfoil reduction. This may allow the size of the IPS and/or IBF hardware to be reduced, eliminated, or altered to meet austere environmental requirements. 
     Energy from a battery system of some sort may drive an electric motor on the engine gearbox or an embedded electronic motor to supply power to a low pressure spool. These arrangements may maintain power output allowing the core to slow down, thus reducing the airflow into the core. Reducing the airflow into the core may reduce the amount of environmental debris pulled through the core of the engine. 
     As a result, erosion on the compressor fan blades and seals as well as sand accretion on the turbine blades may be reduced. The reduction of erosion and sand accretion may improve the life and performance of the engine as well as safety in austere environments. 
     In some embodiments, the engine may remain at high power or thrust setting for takeoff and landing, while at the same time keep the core at low speeds. Similarly, such a configuration may be applicable for aircrafts at high altitude part power conditions. Such configurations may also reduce the ingestion of volcanic ash. 
     The hybrid propulsion system  10 ,  210 ,  310  may be implemented using several different methods. In some embodiments, the pilot of the aircraft may manually input amount of power to be provided to the motor. In other embodiments, the hybrid propulsion system  10 ,  210 ,  310  may be automatic and interface with the aircraft environmental protection systems. In such embodiments, if the pilot or automated system recognizes dangerous or poor environmental conditions, the hybrid propulsion system may activate the programed controls. In this way, the amount of particles ingested into the core of the engine may be reduced and the aircraft and crew may be kept safe. 
     In some embodiments, as power output or thrust increases, mass flow through the core of the engine also increases. This increase in core flow allows external environmental particles to be pulled into the flow stream thereby reducing the effectiveness or performance of the engine. By adding a conventional IPS and/or IBF system, the likelihood or engine failure in austere conditions is reduced. By further implementing the hybrid propulsion system  10 ,  210 ,  310 , corrosion may be further reduced and part lifting due to erosion may be improved, while still maintaining a high power demand output. 
     The present disclosure also relates to methods or arrangements that may reduce the size of infrared suppression (IRS) systems. In typical embodiments. IRS systems may be large, complex, and expensive, and may also adversely affect the performance of the engine. Therefore, there are tradeoffs that may sacrifice engine power, but provide reduced infrared signature. In some embodiments, improved infrared signature capabilities may be desired, forcing more adverse power available trade-offs to be made. 
     As such, the present disclosure teaches the hybrid propulsion system  10 ,  210 ,  310  to augment output power of the engine for exhaust temperature heat reduction. This may allow the size of the IRS system hardware to be reduced, eliminated, or altered to meet even more stringent signature standards. 
     Energy from the battery system may drive an electric motor on the engine gearbox or an embedded electronic motor to supply power to the IRS system thereby reducing the amount of fuel burned by the engine. As a result, the engine exit temperatures may be reduced. In some embodiments, the engine may sit at idle power, while the electric system provides the power. Such arrangements may all but eliminate the heat signature form the aircraft. 
     In some embodiments, the pilot of the aircraft may manually input amount of power to be provided to the motor. In other embodiments, the hybrid propulsion system  10 ,  210 ,  310  may be automatic and interface with the aircraft defensive weapons systems. In such embodiments, if the pilot or automated system recognizes danger, the hybrid propulsion system may activate the programed controls. In this way, the heat signature of the aircraft ay be reduced and the aircraft and crew may be kept safe. 
     In some embodiments, as power output increases, exhaust gas temperatures also increase. As a result, a local “hot-spot” is created that may be used as a target by infrared weapons systems. By adding a conventional IRS system, the infrared targeting capabilities of a weapons system is reduced since the heat signature of the aircraft is minimized. By further implementing the hybrid propulsion system  10 ,  210 ,  310 , the exhaust gas temperatures may be reduced even further, while still maintaining a high power demand output. 
     The present disclosure also relates to methods or arrangements that may reduce aircraft noise. Noise abatement is a compliance guideline in accordance with civil Federal Aviation Administration guidelines. Noise abatement may also be important for military specifications and operations. As such, some aircrafts may employ methods that may restrict high noise movements of the aircraft in areas of high population. Large noise levels may also telegraph the location of an aircraft, which permits quick targeting and engagement of the aircraft by others. 
     In some embodiments, aircrafts may sacrifice engine performance by implementing hardware either internally to the engine or externally to the airframe that may help reduce the overall noise signature of the engine. In some embodiments, noise from the engine may come from many different components, i.e. the fan, the compressor, the combustor, the turbine, the case. The noise from the engine may also come from jet velocity or interaction of the engine components with other various components of the engine. 
     As such, the present disclosure teaches an electrically adaptive noise abatement system that utilizes the hybrid propulsion system  10 ,  210 ,  310  to augment output power of the engine to reduce the core speed of the engine. Reducing the core speed of the engine may in turn reduce the noise form the compressor and may reduce the fuel to the combustor. As a result, other aspects of the engine noise signature may be reduced, allowing the aircraft to reduce the 65 decibel day-night average sound level contour area per Federal Aviation Administration guidelines for noise abatement. This may also allow military operations to be conducted at a reduced low noise level, minimizing possibility of detection. 
     Energy from a battery system of some sort may drive an electric motor on the engine gearbox or an embedded electronic motor to supply power to a low pressure spool. These arrangements may maintain power output allowing the core to slow down, thus reducing the airflow into the core. Reducing the airflow into the core may reduce the noise generated by the core as well as externally transmitted noise into the external and internal environment. In some embodiments, the engine may remain at high power or thrust settings for various stages of flight, i.e. takeoff, landing, approach, climb, loiter, and/or cruise. 
     In some embodiments, the pilot of the aircraft may manually input amount of power to be provided to the motor. In other embodiments, the hybrid propulsion system  10 ,  210 ,  310  may be automatic based on GPS location and/or interfaced with the aircraft defensive weapons systems. In such embodiments, if the pilot or automated system recognizes danger or noise restricted regulations, the hybrid propulsion system may activate the programed controls. In this way, the noise signature of the engine may be reduced. This noise reduction may help maintain safety of the aircraft and/or crew in military applications, or in other embodiments, mitigate exposure in noise-sensitive areas according to Federal Aviation Administration guidelines. 
     In some embodiments, as power output or thrust increases, mass flow through the core of the engine also increases. This increase in core flow may increase combustion, which may result in increased noise generated. By employing an electrically adaptive noise abatement system with the hybrid propulsion system  10 ,  110 ,  210 ,  310 , thrust levels and power levels may remain, but at reduced noise levels. As a result, the possibility of detection is minimized. Such embodiments may also allow reduction of parts/components for reducing noise that may drive engine design. Further, the hybrid propulsion system may also reduce engine noise in more restrictive areas, such as densely populated areas. 
     While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.