GENERATOR FOR AN AIRCRAFT

An electrical generator for an aircraft includes a gas turbine engine having an exhaust section defining an exhaust cavity through which combustion exhaust gases are emitted in a direction defining an exhaust vector, and a magnetohydrodynamic generator having a magnetic field generator forming a magnetic field having at least some magnetic field lines perpendicular to the exhaust vector, and at least one electrode pair, comprising at least one positive electrode and at least one negative electrode, arranged relative to the exhaust section wherein movement of charged particles entrained in the exhaust gas along the exhaust vector generates a DC power output at the at least one electrode pair.

BACKGROUND

Turbine engines, and particularly gas turbine engines, also known as combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for airplanes, including helicopters. In aircraft, gas turbine engines are used for propulsion of the aircraft.

Gas turbine engines also usually provide power for a number of different accessories such as generators, starter/generators, permanent magnet alternators (PMA), fuel pumps, and hydraulic pumps, e.g., equipment for functions needed on an aircraft other than propulsion. In aircraft, gas turbine engines typically provide mechanical power which a generator will convert into electrical energy needed to power accessories.

BRIEF DESCRIPTION

An electrical generator for an aircraft includes a gas turbine engine having an exhaust section defining an exhaust cavity through which combustion exhaust gases are emitted in a direction defining an exhaust vector, and a magnetohydrodynamic generator having a magnetic field generator forming a magnetic field having at least some magnetic field lines perpendicular to the exhaust vector, and at least one electrode pair, comprising at least one positive electrode and at least one negative electrode, arranged relative to the exhaust section wherein movement of charged particles entrained in the exhaust gas along the exhaust vector generates a DC power output at the at least one electrode pair.

DETAILED DESCRIPTION

The described embodiments of the present innovation are directed to power extraction from an aircraft engine, and more particularly to an electrical power system architecture which enables production of electrical power from a turbine engine, more particularly, a gas turbine engine. It will be understood, however, that the innovation is not so limited and has general application to electrical power system architectures in non-aircraft applications, such as other mobile applications and non-mobile industrial, commercial, and residential applications.

FIG. 1is a schematic cross-sectional diagram of a gas turbine engine10for an aircraft with a magnetohydrodynamic (MHD) generator38. The engine10includes, in downstream serial flow relationship, a fan section12, a compressor section15, a combustion section20, a turbine section21, and an exhaust section25. The fan section12includes a fan14, and the compressor section15includes a booster or low pressure (LP) compressor16, a high pressure (HP) compressor18. The turbine section21comprises a HP turbine22, and a LP turbine24. The engine10may further include a HP shaft or spool26that drivingly connects the HP turbine22to the HP compressor18and a LP shaft or spool28that drivingly connects the LP turbine24to the LP compressor16and the fan14. The HP turbine22includes an HP turbine rotor30having turbine blades32mounted at a periphery of the rotor30. Blades32extend radially outwardly from blade platforms34to radially outer blade tips36.

The exhaust section25may include an exhaust nozzle40, which may further comprise an inner surface48and an outer surface50, and the MHD generator38. The inner surface48of the exhaust nozzle40defines an exhaust cavity41. The MHD generator includes a magnetic field generating apparatus, for example, at least one energizable solenoid42, electromagnet, or permanent magnet, and at least one positive electrode44and at least one negative electrode46, defining an electrode pair. As shown, the solenoids42may be operably supported by and/or coupled with the outer surface50of the exhaust nozzle40, while the electrodes44,46may be operably supported by and/or coupled with the inner surface48of the nozzle40. The electrodes44,46are configured along the axial length of the exhaust nozzle40, and shown positioned near the downstream rear of the nozzle40. Alternative configurations are envisioned wherein any combination of the solenoids42and/or the electrodes44,46are supported by and/or coupled with either the inner or outer surfaces48,50of the exhaust nozzle40. Other alternative configurations are envisioned; wherein, the solenoid42and/or the electrodes44,46are supported by and/or coupled with alternative structural elements.

The gas turbine engine10operates such that the rotation of the fan14draws air into the HP compressor18, which compresses the air and delivers the compressed air to the combustion section20. In the combustion section20, the compressed air is mixed with fuel, which for example, may include charged particles, and the air/fuel mixture is ignited, expanding and generating high temperature exhaust gases. The engine exhaust gases, which may still include the charged particles, traverse downstream, passing through the HP and LP turbines22,24, generating the mechanical force for driving the respective HP and LP spools26,28, where the exhaust gases are finally expelled from the rear of the engine10into the exhaust cavity41, in the direction indicated by an exhaust vector52. As shown, the exhaust nozzle40, exhaust cavity41, and exhaust vector52extend along a substantially similar axial direction. In addition, charged particles may alternatively or additionally be introduced into the exhaust cavity41by, alternative components, for example, a spray nozzle or exhaust ring.

FIG. 2illustrates the MHD generator38from an axial perspective along the exhaust nozzle40. As shown, the positive electrode44extends along at least a portion of a first radial segment54of the exhaust nozzle40and the negative electrode46extends along at least a portion of a second radial segment56of the nozzle40. Additionally, while electrodes44,46are shown located on vertically-aligned, opposing sides of each other44,46, relative to the exhaust cavity41, alternative configurations are envisioned wherein the opposing electrodes44,46are aligned or offset from either a vertical or horizontal axis. Embodiments of the innovation are also envisioned wherein the solenoids42are aligned or offset from either a vertical or horizontal axis.

FIG. 3illustrates the operation of the MHD generator38from a perspective view. During operation, the solenoids42are energized to generate a magnetic field58through the exhaust cavity41, which will be substantially perpendicular to the exhaust vector52. As the charged particles entrained in the hot exhaust gases travel along the exhaust vector52, relative to and/or through the magnetic field58, the magnetic field58respectively attracts or repels the particles toward the respective electrodes44,46, and a DC voltage output60is generated across the electrode pair44,46. In the most basic description, the MHD generator38operates by moving a conductor (charged particles of the exhaust) through a magnetic field58, to generate electrical current from the thermal and kinetic energy of the exhaust gases (collectively, the enthalpy from the exhaust gases). As the amount of current generated is mathematically related to the amount of charged particles in the exhaust gases, additives or ionic materials, such as carbon particles or potassium carbonate may be, for instance, included in the fuel or combustion to increase, decrease, and/or target a particular voltage output60for power applications. Additional additives and ionic materials are envisioned. The exhaust gases leaving the exhaust cavity41will have a lower temperature, and consequently, a higher gas density, after generating the voltage output60. The higher gas density results in a higher exhaust gas mass flow rate and, when coupled with the exhaust gas velocity52, results in an increase in engine propulsion efficiency.

The voltage output60may, for instance, provide power to an electrically coupled DC load, the aircraft power system, or may be further coupled with an inverter/converter, which may modify the voltage output60. Examples of modification of the voltage output60may include converting the output60to, for example, 270 VDC, or by inverting the output60to an AC power output, which may be further supplied to an AC load.

Alternative configurations of the electrodes44,46are envisioned, for instance, where the electrodes44,46are positioned more upstream or downstream of the exhaust section25. Additional configurations of the electrodes44,46and solenoids42are also envisioned such that positive and negative electrode44,46positions are reversed, and/or the solenoids42are configured to generate a magnetic field58opposite to that shown.

FIG. 4illustrates an alternative MHD generator138according to a second embodiment of the innovation. The second embodiment is similar to the first embodiment; therefore, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the first embodiment applies to the second embodiment, unless otherwise noted. A difference between the first embodiment and the second embodiment is that the MHD generator138includes a second set of positive and negative electrodes170,172positioned axially along the exhaust nozzle40, such that the second pair of electrodes170,172generate a second voltage output174during operation of the MHD generator138. Alternatively, it is envisioned that each electrode pair44,46,170,172may be axially offset from each other, and/or may be electrically connected in series to generate a larger, single, voltage output. Additionally, it is envisioned that each electrode pair44,46,170,172may have a different physical configuration (e.g. longer, shorter, and/or radial segment) than one or more other electrodes44,46,170,172. Additional electrode pairs may be included to generate any number of different voltage outputs, as needed.

FIG. 5illustrates an alternative MHD generator238according to a third embodiment of the innovation. The third embodiment is similar to the first and second embodiments; therefore, like parts will be identified with like numerals increased by 200, with it being understood that the description of the like parts of the first and second embodiments applies to the third embodiment, unless otherwise noted. A difference of the third embodiment is that the positive electrodes244,270of the MHD generator238each extend along a larger ring-like portion of a first radial segment254of the exhaust nozzle40than in the first embodiment, and the negative electrodes246,272each extends along a larger ring-like portion of a second radial segment256of the nozzle40than in the first embodiment. Additionally, each of the electrodes272,270,246,244are electrically connected in series by conductors280, which may extend along the inner surface48, outer surface50, or integrated with the exhaust nozzle40, such that the MHD generator238generates a single voltage output260. It is envisioned that each electrode244,246,270,272may have a different physical configuration (e.g. longer, shorter, and/or radial segment254,256) than one or more other electrodes244,246,270,272.

FIG. 6illustrates an alternative MHD generator338according to a fourth embodiment of the innovation. The fourth embodiment is similar to the first, second, and third embodiments; therefore, like parts will be identified with like numerals increased by 300, with it being understood that the description of the like parts of the first, second, and third embodiments applies to the fourth embodiment, unless otherwise noted. A difference of the fourth embodiment is that the first set of series-connected electrodes272,270,246,244are interweaved with a second set of similar series-connected electrodes386,384,390,388, connected by a second conductor382, such that the first set of series-connected electrodes272,270,246,244and the second set of series-connected electrodes386,384,390,388generate a respective first voltage output260and a second voltage output374.

FIG. 7illustrates an alternative MHD generator438according to a fifth embodiment of the innovation. The fifth embodiment is similar to the first, second, third, and fourth embodiments; therefore, like parts will be identified with like numerals increased by 400, with it being understood that the description of the like parts of the first, second, third, and fourth embodiments applies to the fifth embodiment, unless otherwise noted. A difference of the fifth embodiment is the alternative series connection of the first set of electrodes472,470,490,488, coupled via the first conductor480and generating a first voltage output460, and the series connection of the second set of electrodes486,484,446,444, coupled via the second conductor482and generating a second voltage output474. Another difference of the fifth embodiment is that the second set of electrodes486,484,446,444are flanked on either axial end by an electrode pair of the first set of electrodes472,470,490,488.

Many other possible embodiments and configurations in addition to that shown in the above figures are contemplated by the present disclosure. For example, additional permutations of electrode configurations are envisioned. In another example, one or more of the electrodes, electrode pairs, or electrode rings may be diagonally offset relative to the exhaust vector, or perpendicular to the exhaust vector. Additionally, the design and placement of the various components may be rearranged such that a number of different in-line configurations could be realized.

The embodiments disclosed herein provide a MHD generator integrated with a gas turbine engine. One advantage that may be realized in the above embodiments is that the above described embodiments are capable of generating and/or converting exhaust gas enthalpy into electricity for power electronics. This increases the efficiency of the overall electrical generating efficiency of the turbine engine. Additionally, the increase in electrical generation efficiency may allow for a reduction in weight and size over conventional type aircraft generators. Alternatively, the electricity generation of the MHD generator may provide for redundant electrical power for the aircraft, improving the aircraft power system reliability.

Another advantage that may be realized in the above embodiments is that the conversion of the exhaust gas enthalpy into electricity lowers the exhaust gas temperature, which increases the exhaust gas density. The increase gas density results in an increase in momentum, and thus, an increase in the propulsion efficiency of the gas turbine engine. An increase in the propulsion efficiency may result in improved operating or fuel efficiency for the aircraft.

When designing aircraft components, important factors to address are size, weight, and reliability. The above described MHD generators will be able to provide regulated AC or DC outputs with minimal power conversion equipment, making the complete system inherently more reliable. This results in a lower weight, smaller sized, increased performance, and increased reliability system. Reduced weight and size correlate to competitive advantages during flight.

To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments is not meant to be construed that it may not be, but is done for brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure. The primary differences among the exemplary embodiments relate to the configuration of the electrode pairs, and these features may be combined in any suitable manner to modify the above described embodiments and create other embodiments.

This written description uses examples to disclose the innovation, including the best mode, and also to enable any person skilled in the art to practice the innovation, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the innovation is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.