Jet engine with electromagnetic wave based plasma heating chamber

Abstract

The present invention relates to a combustion-alternative heating structure for an intake-type gas turbine. Specifically, it belongs to the field of jet engine technology that suppresses electromagnetic leakage by including a plasma heating chamber that heats compressed air supplied from a compressor with an electromagnetic-based plasma torch, a dual structure of a metal-based outer casing and a dielectric-based inner liner suitable therefor, an electromagnetic shielding section around the torch port, and grounding of the outer casing. Furthermore, the turbine inlet temperature is maintained within a target range through closed-loop power control based on sensor signals, and in some embodiments, cooling and rotational flow stabilization are achieved by providing a torch regenerative cooling path and a spiral groove in the inner liner.

Description

Technology Field

[0001] The present invention relates to a combustion-alternative heating structure for an intake-type gas turbine. Specifically, it belongs to the field of jet engine technology that suppresses electromagnetic leakage by including a plasma heating chamber that heats compressed air supplied from a compressor with an electromagnetic-based plasma torch, a dual structure of a metal-based outer casing and a dielectric-based inner liner suitable therefor, an electromagnetic shielding section around the torch port, and grounding of the outer casing. Furthermore, the turbine inlet temperature is maintained within a target range through closed-loop power control based on sensor signals, and in some embodiments, cooling and rotational flow stabilization are achieved by providing a torch regenerative cooling path and a spiral groove in the inner liner. Background Technology

[0003] A turbojet engine generally consists of a compressor, combustion chamber, turbine, and nozzle, and generates high-temperature, high-pressure gases by igniting a fuel-air mixture in the combustion chamber. While this chemical combustion method has matured based on accumulated operational technology, it has structural limitations, such as the complexity of fuel storage and injection systems, ignition stability issues, the burden of exhaust gas treatment, and reduced component lifespan due to high temperatures.

[0004] In conventional combustion chamber designs, techniques to stabilize the flame and homogenize the temperature distribution through multi-stage air intake and swirl flow have been widely used. However, since this is based on the premise of a flame, inherent combustion problems such as flame extinction, re-ignition, and combustion instability persist, and even when diluting air is introduced to control the Turbine Inlet Temperature (TIT), it is difficult to completely eliminate rapid thermal fluctuations and thermal fatigue.

[0005] Plasma heating using electromagnetic waves (microwaves or RF) is a technology that ionizes and heats gases by combining electrical energy into electromagnetic waves, and has been applied in areas such as material processing and ignition assistance. To apply this as a primary heating method for intake-type jet engines, integrated thermal management—including plasma stability under high mass flow rates and relatively high pressure environments, electromagnetic coupling efficiency, and turbine inlet temperature control—must be achieved.

[0006] In electromagnetic wave-based heating devices, electromagnetic leakage can cause interference with surrounding electronic devices; therefore, ensuring Electromagnetic Compatibility (EMC) through structural shielding and grounding is essential. To this end, a dual structure is required in which a metal-based outer casing is grounded to operate as a Faraday cage, while a dielectric liner, such as quartz, is placed inside to accommodate and stabilize the plasma. Additionally, leakage reduction structures, such as RF chokes (RFCs) and shielding covers, must be installed around the torch port.

[0007] Furthermore, an approach that directly limits the turbine inlet temperature through sensor feedback-based closed-loop power control, rather than relying on conventional dilution structures, is desirable. For example, a system is required that combines downstream temperature and pressure sensors, measurement of plasma emission light through an optical observation window in the liner, and monitoring of reflected power in the power path to actively regulate the output or frequency of electromagnetic waves, and provides protection through a power cut-off interlock in the event of an abnormality.

[0008] In terms of flow, it is advantageous to position the plasma torch tangentially to the circumference of the inner liner to form rotational flow and promote residence time and mixing. Additionally, it is necessary to stabilize rotation and suppress localized energy concentration or arc generation of the plasma through flow guides, such as helical grooves on the inner surface of the liner. Thermal efficiency and durability can be enhanced by cooling the torch itself with a portion of compressed air through a regenerative cooling channel and then reintroducing it into the heating chamber.

[0009] Meanwhile, RF heating technologies in the field of space electric propulsion, such as helicon waves or Variable Specific Impulse Magnetoplasma Rockets (VASIMR), belong to non-inspiratory rocket propulsion that utilizes radio wave heating and magnetic nozzles in a vacuum environment, and do not include compressors and turbines and do not use atmospheric oxygen. The present invention relates to an inspiratory gas turbine based on atmospheric intake and turbine driving, and is clearly distinguished from electric propulsion rockets in its structure, operating environment, and application.

[0010] In short, there is a need for a jet engine heating structure that adopts electromagnetic plasma as the primary heating means instead of combustion, integrating electromagnetic shielding and grounding based on a dual structure of a metal outer casing and dielectric liner, mixing stabilization through a tangential torch and flow guide, and closed-loop control and interlock protection based on optical / temperature / reflected power sensors. Prior art literature

[0012] Registered Patent No. 10-1458592 (Small microwave plasma generator with improved ease of manufacturing and mechanical structural stability) The problem to be solved

[0013] The present invention aims to solve the following problems in order to solve the aforementioned problems.

[0014] The present invention provides a jet engine structure that reduces exhaust emissions and increases ignition stability by heating compressed air using electromagnetic wave-based plasma without using fuel combustion.

[0015] The present invention provides a plasma heating chamber that suppresses electromagnetic leakage and minimizes electromagnetic interference to surrounding devices by including a dual structure comprising a metal-based outer casing and a dielectric-based inner liner, and an electromagnetic shielding portion around the torch port.

[0016] The present invention provides a protection design that ensures electrical continuity and improves electromagnetic compatibility by enabling operation as a Faraday cage through the grounding of the outer casing.

[0017] The present invention provides a structure that controls residence time and mixing and suppresses local energy concentration of plasma or arc generation by arranging a plasma torch in a circumferential tangential direction of an inner liner and stably forming rotational flow using a helical groove on the inner surface of the inner liner.

[0018] The present invention provides a closed-loop power control system that limits the turbine inlet temperature to a target range without a dilution structure by measuring the plasma emission light spectrum through an optical sensor, monitoring the coupling state through a reflected power sensor, and actively adjusting the output or frequency of electromagnetic waves based on the correlation between these sensor signals and the turbine inlet temperature.

[0019] The present invention provides a protection mechanism that enhances driving safety and reliability by including an interlock that cuts off power when an abnormal condition is detected.

[0020] The present invention provides a cooling configuration that improves thermal efficiency and durability by applying a regenerative cooling channel to a plasma torch, cooling the torch with air branched from the compressor, and then recirculating the heated air into the chamber.

[0021] The present invention provides a configuration that selectively heats the base plasma and core region by adopting an electromagnetic coupling structure, such as waveguide coupling or antenna radiation, and a dual-frequency superposition heating method, and secures stable plasma heating performance even under high mass flow rate conditions.

[0022] The present invention provides an engineering platform that adopts a modular coupling structure including a flange coupling and a replaceable dielectric liner to enhance fabrication, maintenance, and testing applicability, and facilitates integration with existing turbocharger-based test devices.

[0023] The problems solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by a person skilled in the art from the description below. means of solving the problem

[0025] According to various embodiments of the present invention, a plasma jet engine is provided, comprising: a compression unit for inhaling and compressing air; a plasma heating chamber for heating compressed air supplied from the compression unit with electromagnetic waves; a turbine driven by the heated gas from the plasma heating chamber; and a nozzle for spraying gas that has passed through the turbine, wherein the plasma heating chamber comprises: (i) a double structure consisting of a metal-based outer casing and a dielectric material-based inner liner coaxially disposed inside the outer casing; (ii) a plasma torch disposed toward the inside of the inner liner, wherein the plasma torch is configured to generate plasma based on electromagnetic waves; (iii) a power control unit for closed-loop control of the electromagnetic output supplied to the plasma torch based on a sensor signal; and (iv) an electromagnetic shielding unit located around the plasma torch, wherein the outer casing is configured to block electromagnetic leakage to suppress interference with an external device. Effects of the invention

[0027] The present invention can provide a jet engine structure that reduces exhaust gases and increases ignition stability by heating compressed air using electromagnetic wave-based plasma without using fuel combustion.

[0028] The present invention can provide a plasma heating chamber that suppresses electromagnetic leakage and minimizes electromagnetic interference to surrounding devices by including a dual structure consisting of a metal-based outer casing and a dielectric-based inner liner, and an electromagnetic shielding portion around the torch port.

[0029] The present invention can provide a protection design that ensures electrical continuity and improves electromagnetic compatibility by enabling operation as a Faraday cage through the grounding of the outer casing.

[0030] The present invention can provide a structure that controls residence time and mixing and suppresses local energy concentration of plasma or arc generation by arranging a plasma torch in the circumferential tangential direction of an inner liner and stably forming rotational flow using a helical groove on the inner surface of the inner liner.

[0031] The present invention can provide a closed-loop power control system that limits the turbine inlet temperature to a target range without a dilution structure by measuring the plasma emission light spectrum through an optical sensor, monitoring the coupling state through a reflected power sensor, and actively adjusting the output or frequency of electromagnetic waves based on the correlation between these sensor signals and the turbine inlet temperature.

[0032] The present invention can provide a protection mechanism that enhances driving safety and reliability by including an interlock that cuts off the power when an abnormal condition is detected.

[0033] The present invention can provide a cooling configuration that improves thermal efficiency and durability by applying a regenerative cooling channel to a plasma torch, cooling the torch with air branched from the compressor, and then recirculating the heated air into the chamber.

[0034] The present invention can provide a configuration that selectively heats the base plasma and core region and secures stable plasma heating performance even under high mass flow rate conditions by adopting an electromagnetic coupling structure, such as waveguide coupling or antenna radiation, and a dual-frequency superposition heating method.

[0035] The present invention can provide an engineering platform that adopts a modular coupling structure including a flange coupling and a replaceable dielectric liner to enhance fabrication, maintenance, and testing applicability and facilitate integration with existing turbocharger-based test devices.

[0036] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0038] FIG. 1 illustrates the overall configuration of a jet engine test module including a plasma heating chamber according to one embodiment of the present invention and a conceptual diagram of the heating chamber section. FIG. 2 is a three-dimensional rendering image showing a metal outer casing of a plasma heating chamber that can be applied to a prototype of the present invention. FIG. 3 is a front view, side view, and cross-sectional view of a prototype plasma heating chamber of the present invention, illustrating the double structure of a metal outer casing and a dielectric inner liner, a flange joint, and the arrangement of a plasma torch port. Specific details for implementing the invention

[0039] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0041] FIG. 1 illustrates the overall configuration of a jet engine test module including a plasma heating chamber according to one embodiment of the present invention and a conceptual diagram of the heating chamber section.

[0042] Figure 1 shows the overall configuration of a jet engine test module. The test module includes a compressor, a flow path duct, a plasma heating chamber, a turbine, an exhaust nozzle, a power supply, a control, an electromagnetic shielding, a cooling and grounding configuration, and a support frame. Each component is detachably connected via flange connections, making testing and maintenance easy.

[0043] The compressor draws in external air and compresses it to a predetermined pressure, and is connected to the flange on the front of the heating chamber through an outlet duct. A backflow prevention structure and a flow control valve may be installed in the duct. A vibration isolation mount is placed between the compressor and the heating chamber to reduce structural interference.

[0044] The plasma heating chamber is a dual structure consisting of a metal-based outer casing and a dielectric-based inner liner positioned coaxially within it. The outer casing is grounded to function as a Faraday cage, and its fasteners and contact surfaces are designed to ensure electrical continuity along the outer periphery of the chamber. A quartz tube is preferred for the inner liner, which is responsible for heat resistance and insulation in the region directly contacted by the plasma.

[0045] A port for a plasma torch is provided on the side of the heating chamber. The plasma torch is oriented tangentially to the circumference of the inner liner to generate rotational flow. Structures for electromagnetic shielding are positioned around the torch port, typically utilizing choke grooves, shielding covers, and electromagnetic gaskets. This shielding suppresses electromagnetic leakage to the outside, thereby reducing interference with surrounding devices.

[0046] The torch may include a regenerative cooling path. A portion of the compressed air branched from the compressor outlet passes through the inside of the torch to cool it, and then is heated and introduced into the heating chamber. This configuration increases the durability and thermal efficiency of the torch. The cooling path may include a leak-proof seal and a flow control means.

[0047] Spiral grooves can be formed on the inner surface of the inner liner. These grooves guide the rotation created by the tangentially incoming jet, promote mixing, and suppress localized energy concentration of the plasma or arc generation. The liner is provided with a replaceable structure, allowing for rapid testing of various materials and shapes.

[0048] A turbine is positioned downstream of the heating chamber. A ceramic insulating ring is placed at the junction between the turbine and the heating chamber to block heat conduction, while a metal bellows is installed to absorb differences in thermal expansion and vibrations. This coupling structure simultaneously reduces both thermal and mechanical interference.

[0049] The power supply unit provides electromagnetic energy to the plasma torch. The coupling method can be implemented using one or more of waveguide coupling or antenna radiation methods. Sensors measuring reflected power are placed in the power path to monitor the coupling status. If the reflected power exceeds a threshold, the control unit determines the condition to be abnormal and cuts off the power.

[0050] The control unit collects signals from downstream temperature and pressure sensors, plasma emission spectra measured through the liner's observation window, and reflected power sensors. Based on the correlation between these sensor signals and the turbine inlet temperature, the control unit adjusts the output or frequency of electromagnetic waves. This maintains the turbine inlet temperature within the target range without the need for a dilution structure. If an abnormal condition is detected, a safety interlock is activated to shut off the power and close the valve.

[0051] The support frame is positioned to maintain axial alignment of the compression section, heating chamber, and turbine section, and includes cable trays and piping supports. The power supply and control sections are housed inside a shielded housing to be protected from electromagnetic waves and environmental factors. The housing is equipped with a grounding terminal, an emergency stop switch, and a door interlock.

[0052] The operation procedure proceeds in the order of the purge phase, torch ignition, spectrum and temperature verification, closed-loop control of output or frequency, and the normal operation phase. In the shutdown procedure, power cutoff, residual heat removal, and purge cycling are performed.

[0053] The conceptual diagram of FIG. 1 schematically illustrates the mutual arrangement and signal flow of the above components, and the shapes and quantities of the parts are simplified for clarity of explanation. Various variations performing the same function are permitted within the scope of the spirit of the present invention.

[0055] FIG. 2 is a three-dimensional rendering image showing a metal outer casing of a plasma heating chamber that can be applied to a prototype of the present invention.

[0056] Figure 2 is a three-dimensional rendering example showing only the metal outer casing of a plasma heating chamber. The outer casing consists of a cylindrical body, a front flange, and a rear end cap. This casing simultaneously performs the roles of structural support, airtightness, electromagnetic shielding, and grounding.

[0057] A flat flange surface is formed on the front and is joined to the compression section outlet duct in an axially aligned state. Fastening holes are arranged at even intervals along bolt circles on the flange, and an inlet opening is located in the center. A gasket seat or O-ring groove may be machined on the flange surface, and a pilot boss to aid alignment may be included on the back of the flange.

[0058] A port into which a plasma torch is inserted is provided on the side of the cylindrical body. The axis of the port is angled to face the tangential direction of the inner liner, and a structure for electromagnetic shielding is placed around the port. Typically, an electromagnetic choke utilizing an annular groove on the outer surface of the port, a shielding cover, or an electromagnetic shielding gasket can be applied. A cooling channel can be formed in the port adapter to mitigate local overheating around the torch assembly.

[0059] The external casing is designed with conductive paths at welds and fasteners to ensure electrical continuity. Grounding lugs are provided on the outer wall of the casing to ensure a secure connection to the test stand ground. The grounding path is configured to form a continuous metal path extending from the flange to the port adapter and shielding cover.

[0060] The rear end is closed with a curved end cap. The curved shape alleviates thermal stress concentration and increases rigidity against internal pressure fluctuations. If necessary, an exhaust-side sensor port or an inspection port may be added to the end cap, and these ports feature both sealed and shielded structures.

[0061] The outer surface may be coated with a heat-resistant paint and an anti-oxidation treatment. Reinforcement rings are placed around the port and adjacent to the flange to increase mechanical rigidity and leakage resistance. Lifting eyes for transport and installation, brackets that connect to the support frame, and studs for securing cables and piping may be installed in the casing.

[0062] The manufacturing process involves precisely forming the flange surface and port coordinates through machining following cylindrical welding, followed by non-destructive testing and leak testing. To ensure electromagnetic compatibility, leakage electromagnetic measurements, grounding continuity measurements, and mounting torque verification of the port shielding are performed after assembly.

[0063] The rendering image in FIG. 2 is an example for understanding the exterior, so internal elements such as the inner liner, torch body, sensor, and regenerative cooling channel are omitted. However, in the actual prototype, spacers and alignment pins are arranged so that the outer casing and the inner liner are coaxially aligned, and the shielding part and the ground part of the port are assembled as a single unit.

[0065] FIG. 3 is a front view, side view, and cross-sectional view of a prototype plasma heating chamber of the present invention, illustrating the double structure of a metal outer casing and a dielectric inner liner, a flange joint, and the arrangement of a plasma torch port.

[0066] FIG. 3 shows a front view, a side view, and a cross-sectional view of a prototype plasma heating chamber of the present invention. The axes of each drawing coincide with each other.

[0067] The front view shows the front flange of the metal outer casing. The flange features uniformly spaced fastening holes along bolt circles to provide a hermetic connection with the compression outlet duct. An inlet opening is formed in the center, and a gasket seat or O-ring groove may be provided on the flange surface. Pilot bosses may be added to aid alignment if necessary, but they are omitted from the drawing for clarity.

[0068] The side view illustrates the overall external shape of the cylindrical outer casing and the plasma torch port on the side. The torch port penetrates the outer casing and communicates with the inner liner sidewall, and the angle of the torch axis is set so as to point in the direction tangential to the circumference of the inner liner. Structures for electromagnetic shielding may be placed around the port, examples of which include choke grooves, shielding covers, and electromagnetic gaskets. If cooling is required, cooling channels may be formed in the port adapter, but in this drawing, only the opening is shown for simplification.

[0069] The cross-sectional view clearly shows a dual structure in which the outer casing and the dielectric inner liner are arranged coaxially. A quartz tube is preferred for the inner liner, which electrically insulates the plasma region and reduces thermal damage. The outer casing is made of metal and grounded to function as a Faraday cage, designed to ensure electrical continuity between the fasteners and contact surfaces. The inner liner is supported by the outer casing via support spacers, and a gap may be set to absorb the difference in thermal expansion.

[0070] A flange space for connection with the turbine is depicted on the downstream side of the cross-section. At the connection point, a ceramic insulating ring to block heat conduction and a metal bellows for vibration absorption and thermal expansion compensation may be installed. These components contribute to minimizing thermal and mechanical interference between the heating chamber and the turbine.

[0071] A helical groove can be formed on the inner surface of the inner liner to stabilize rotational flow. This groove guides the rotation created by the torch jet flowing in a tangential direction, thereby controlling the residence time and suppressing localized energy concentration of the plasma or arc generation. The specific shape of the helical groove can be modified within the range described in the examples, and a representative shape is schematically shown in the drawings.

[0072] The plasma torch can transmit electromagnetic energy into the chamber using one or more of waveguide coupling or antenna radiation methods. Sensors measuring reflected power can be placed in the power path to monitor the coupling status, and an interlock is activated in which the control unit cuts off the power when a threshold is exceeded. Although these controls and sensor placements have been omitted to avoid complexity in the drawings, they function importantly in the implementation of the present invention.

[0073] In the front and side views, grounding lugs for the external casing, cable routing brackets, lifting eyes, etc., can be optionally added. These auxiliary components facilitate manufacturing and maintenance, and contribute to ensuring electromagnetic compatibility and safe operation. The drawings focus on the layout of the main components, with detailed parts omitted.

[0074] Figure 3 shows the basic design of a prototype heating chamber considering electromagnetic shielding, structural support, and an interface with a turbine, focusing on the dual structure of a metal outer casing and a dielectric inner liner, flange joints, and the arrangement of plasma torch ports.

[0076] According to various embodiments of the present invention, a plasma jet engine is provided. The plasma jet engine comprises: a compressor that inhales and compresses air; a plasma heating chamber that heats the compressed air supplied from the compressor with electromagnetic waves; a turbine driven by the heated gas from the plasma heating chamber; and a nozzle that sprays the gas passing through the turbine. The plasma heating chamber comprises: (i) a double structure consisting of a metal-based outer casing and a dielectric material-based inner liner coaxially disposed inside the outer casing; (ii) a plasma torch disposed toward the inner side of the inner liner, wherein the plasma torch is configured to generate plasma based on electromagnetic waves; (iii) a power control unit that controls the electromagnetic output supplied to the plasma torch in a closed loop based on a sensor signal; and (iv) an electromagnetic shielding unit located around the plasma torch. The outer casing is configured to block electromagnetic leakage to suppress interference with external devices.

[0077] This configuration organically combines a dual-structure chamber consisting of a metal outer casing and a dielectric inner liner, an internal plasma torch, closed-loop power control, and an electromagnetic shielding section, thereby simultaneously ensuring stable and efficient plasma heating performance and electromagnetic safety. This allows for the stable maintenance of high-temperature plasma while effectively suppressing electromagnetic interference (EMI) to external electronic devices, significantly enhancing the reliability and practicality of the plasma jet engine.

[0079] According to various embodiments of the present invention, the plasma torch may be positioned in a circumferential tangential direction of the inner liner and oriented to form a rotational flow.

[0080] This configuration forms a strong rotational flow within the chamber by positioning the plasma torch tangentially. This vortex stably confines the plasma to the center of the chamber and promotes mixing with compressed air, thereby improving heating efficiency and uniformity. Additionally, it prevents the high-temperature plasma from coming into direct contact with the inner liner, which increases the durability of the liner and ensures the long-term operational stability of the engine.

[0082] According to various embodiments of the present invention, the power control unit may include an optical sensor that measures a plasma emission spectrum within the plasma heating chamber. The power control unit may be configured to limit the turbine inlet temperature to within a target range by actively adjusting the output or frequency of electromagnetic waves based on the correlation between the intensity or ratio of a specific spectral line measured by the optical sensor and the turbine inlet temperature.

[0083] This configuration precisely controls the turbine inlet temperature non-contactually by analyzing the emission spectrum of the plasma itself. This offers a faster response speed than conventional thermocouple methods and enables accurate measurements even in harsh environments, thereby preventing thermal damage to turbine blades and allowing the engine to be safely utilized up to its limits. Consequently, it effectively improves both engine responsiveness and stability.

[0085] According to various embodiments of the present invention, the plasma torch may include a regenerative cooling type cooling channel configured such that a portion of compressed air branched from the outlet of the compression unit is introduced to cool the torch, and then heated and supplied to the plasma heating chamber.

[0086] This configuration adopts a regenerative cooling method that cools the plasma torch by utilizing a portion of the engine's compressed air. This eliminates the need for a separate cooling system, reducing the engine's weight and complexity, while providing a dual benefit of improving the engine's overall thermal efficiency since the air used for cooling is preheated before being supplied to the chamber.

[0088] According to various embodiments of the present invention, the metal outer casing may be configured to operate as a grounded Faraday cage to have electrical continuity.

[0089] This configuration operates the metal outer casing as a grounded Faraday cage to effectively shield against the powerful electromagnetic waves generated during plasma generation. This effectively blocks electromagnetic interference (EMI) to the aircraft's sophisticated navigation and communication systems, thereby providing critical safety that ensures stable flight in any operating environment.

[0091] According to various embodiments of the present invention, the inner liner may be configured to have a helical groove formed on its inner surface to stably guide the rotational flow formed by the plasma torch and to suppress localized energy concentration of the plasma or arc generation. The inner liner may be a replaceable quartz tube.

[0092] This configuration forms helical grooves in the inner liner to more stably induce and control rotational flow. This structure suppresses plasma instability and prevents arc concentration at specific points, thereby minimizing damage to the inner liner. Furthermore, by manufacturing the liner from a replaceable quartz tube, it offers practical benefits such as improved ease of maintenance and reduced operating costs.

[0093] The inner liner is preferably made of quartz, but is not limited thereto, and can also be formed from high heat-resistant ceramic materials such as aluminum nitride (AlN) or boron nitride (BN).

[0095] According to various embodiments of the present invention, electromagnetic energy generated from the plasma torch may be transmitted to the plasma heating chamber through a dedicated passage and amplified, or may be directly radiated into the interior of the plasma heating chamber through an antenna. Specifically, regarding the amplification after transmission of electromagnetic energy through a dedicated passage, the electromagnetic field strength may be configured to increase through resonance or coupling.

[0096] This configuration enables the delivery of high-output electromagnetic energy to compressed air with minimal loss by implementing a waveguide-resonator coupling or antenna radiation method for transferring electromagnetic energy to the chamber. This is a key component for efficiently generating high-density, high-temperature plasma, which consequently improves the thrust performance of the engine.

[0098] According to various embodiments of the present invention, the plasma jet engine may include a power sensor that measures the reflected power of electromagnetic waves reflected from the plasma heating chamber. If the reflected power measured by the power sensor exceeds a set threshold, it is identified as an abnormal state, and the plasma heating chamber may be configured to have its power cut off.

[0099] This configuration detects reflected power that changes immediately in real time when abnormal conditions, such as plasma extinction or instability, occur. This enables the detection of critical system errors much faster than temperature or pressure sensors, thereby enabling the implementation of a highly reliable safety system that protects expensive power supply units from overload and prevents abnormal engine operation.

[0101] According to various embodiments of the present invention, the coupling portion between the plasma heating chamber and the turbine may be configured to minimize thermal or mechanical interference between the plasma heating chamber and the turbine by including a ceramic thermal break ring for blocking heat conduction and metal bellows for absorbing vibration and compensating for differences in thermal expansion.

[0102] This configuration resolves connection issues between an ultra-high temperature plasma chamber and a precision turbine through a functional joint comprising a ceramic insulating ring and a metal bellows. This joint blocks the conduction of extreme heat from the chamber to the turbine and effectively absorbs vibrations and thermal expansion during operation, thereby significantly improving the structural stability and durability of the turbine.

[0103] In addition to ceramic insulating rings and metal bellows, high-temperature composite gaskets or wire mesh dampers may be used at the joint to block vibration and heat transfer.

[0105] According to various embodiments of the present invention, the plasma torch may use a dual-frequency superposition method to generate a base plasma of a large volume with electromagnetic waves of a first frequency and simultaneously superimpose electromagnetic waves of a second frequency onto the central region of the base plasma to intensively heat the core region.

[0106] This configuration independently optimizes plasma generation and heating by using a method that superimposes two frequencies with different characteristics. By creating a broad and stable base plasma with the first frequency and concentrating the heating of its center with the second frequency, it is possible to secure high energy efficiency and a wide operating range that are difficult to achieve with a single-frequency method. This results in a dramatic improvement in the engine's thrust and fuel efficiency performance.

[0108] According to various embodiments of the present invention, a plurality of plasma torches may be further included spaced apart along the circumferential direction of the plasma heating chamber. The power control unit may be configured to individually control the phase and output of electromagnetic waves supplied to each of the plurality of plasma torches so that a predetermined temperature distribution is formed in the radial and axial directions of the inner liner.

[0109] The present configuration is characterized by including a plurality of plasma torches spaced apart along the circumferential direction of a plasma heating chamber, and a power control unit that individually controls the phase and output of electromagnetic waves supplied to each plasma torch. The present configuration is a multi-point heating control structure that is distinguished from a simple heating structure based on a single torch in that it is designed to form a desired temperature distribution in the radial and axial directions of an inner liner. The present configuration is significant in that it provides an advanced thermal management means capable of spatially and finely adjusting the temperature field within the plasma heating chamber.

[0110] This configuration has the effect of reducing localized overheating caused by heat concentration and thermal fatigue of materials by uniformly distributing the temperature inside the plasma heating chamber or intentionally forming a gradient through phase and output control of multiple plasma torches. This configuration contributes to alleviating the thermal load on turbine blades and stabilizing efficiency by reducing the temperature deviation of the gas entering the turbine inlet. Furthermore, this configuration can dynamically adjust the amount of heating in specific areas according to operating conditions, which is advantageous for optimizing thrust and efficiency in various operating modes.

[0112] According to various embodiments of the present invention, the power control unit may apply electromagnetic waves having different phase differences to the plurality of plasma torches to form an electromagnetic wave pattern that rotates within the plasma heating chamber. The rotating electromagnetic wave pattern may be configured to increase the residence time of the flow within the plasma heating chamber.

[0113] The present configuration is a structure in which a power control unit applies electromagnetic waves having different phase differences to a plurality of plasma torches to form a rotating electromagnetic wave pattern inside a plasma heating chamber. By utilizing the phase difference of the electromagnetic waves, the present configuration is designed so that the electromagnetic energy distribution rotates in a circumferential direction over time, thereby providing a moving heating pattern rather than a fixed local heating point. The present configuration is significant in that it implements a dynamic heating mechanism that disperses energy more evenly throughout the flow through this rotating electromagnetic wave pattern.

[0114] This configuration causes specific streamlines of the flow within the plasma heating chamber to repeatedly pass through the heating region due to a rotating electromagnetic wave pattern, thereby substantially increasing the residence time and energy absorption of the gas. As a result, this configuration can increase the total enthalpy rise of the exit gas even under the same inlet conditions, contributing to the improvement of thrust density in plasma jet engines. Furthermore, due to the rotational pattern, the temperature and electromagnetic field distributions are averaged over time, providing a stabilization effect that reduces the possibility of localized thermal peaks and wall damage.

[0116] According to various embodiments of the present invention, the inner liner may include a first dielectric layer disposed on the inner circumferential side of the plasma heating chamber and a second dielectric layer disposed on the outer side of the first dielectric layer. The first dielectric layer and the second dielectric layer may be selected to have different dielectric constants to optimize the resonant frequency band and electromagnetic wave absorption efficiency of the plasma heating chamber.

[0117] The present configuration is a multilayer dielectric structure in which an inner liner comprises a first dielectric layer disposed on the inner surface of a plasma heating chamber and a second dielectric layer disposed on the outer side thereof, wherein the two dielectric layers are selected to have different dielectric constants. The present configuration allows for the design of electromagnetic characteristics such that the plasma heating chamber has high electromagnetic energy storage and absorption characteristics in a specific resonant frequency band through the combination of dielectric constants, and provides a greater degree of freedom in resonance characteristics compared to a single dielectric layer structure. The present configuration is significant in that it enables functional division, in which the first dielectric layer is responsible for heat resistance and electromagnetic transmission characteristics in the region directly exposed to the plasma, and the second dielectric layer performs the role of correcting resonance characteristics and impedance matching on the outer side.

[0118] This configuration utilizes a multilayer dielectric structure with different dielectric constants, which allows for more efficient absorption of electromagnetic waves and a reduction in reflected power within the plasma heating chamber. By adjusting the resonant frequency band to meet design objectives and optimally matching it with the frequency of the electromagnetic source used, this configuration improves the efficiency of converting electromagnetic energy into plasma energy. Furthermore, by leveraging the electromagnetic dispersion characteristics between dielectric layers, this configuration mitigates wall-side electric field distribution and reduces localized electric field concentration, thereby enhancing the lifespan and reliability of the liner.

[0120] According to various embodiments of the present invention, the plasma jet engine may further include a wall surface temperature sensor attached to the outer surface of the outer casing or the inner liner and a rotational speed sensor for detecting the rotational speed of the turbine. The power control unit may be configured to increase or limit the electromagnetic output by considering the sensor signals from the wall surface temperature sensor and the rotational speed sensor together, so as not to exceed the allowable temperature of the inner liner while satisfying the required thrust level.

[0121] This configuration includes a wall temperature sensor attached to the outer surface of the outer casing or inner liner of a plasma jet engine and a rotational speed sensor that detects the rotational speed of the turbine, and is structured such that a power control unit considers these sensor signals together to increase or limit the electromagnetic output. This configuration is characterized by the fact that the wall temperature sensor monitors the thermal state of the plasma heating chamber and the inner liner in real time, and the rotational speed sensor provides feedback information that indirectly indicates the load and thrust status of the turbine. This configuration is significant in that it implements an advanced control architecture that controls the electromagnetic output through a dual feedback path that simultaneously reflects thermal safety limits and performance requirements.

[0122] This configuration controls electromagnetic output by considering both wall temperature and rotational speed, thereby maintaining the required thrust while ensuring that the allowable temperature of the inner liner is not exceeded. This configuration enables balanced control that allows for an increase in output when the rotational speed decreases due to increased turbine load, but automatically limits the output when the wall temperature approaches a reference value to prevent structural damage. As a result, this configuration can simultaneously ensure the performance and durability of the plasma jet engine and has the effect of reducing abnormal shutdowns or shortened lifespan caused by overheating.

[0124] According to various embodiments of the present invention, the nozzle may include a variable nozzle mechanism for changing the effective cross-sectional area and exhaust angle of the nozzle neck. The power control unit may be configured to drive the variable nozzle mechanism based on sensor signals from a pressure sensor that detects pressure within the plasma heating chamber and a temperature sensor that detects the turbine inlet temperature, so that the cross-sectional area and exhaust angle of the nozzle neck are automatically adjusted according to the plasma heating state, thereby optimizing thrust and fuel efficiency.

[0125] The present configuration includes a variable nozzle mechanism for changing the effective cross-sectional area and exhaust angle of the nozzle neck, and a power control unit drives the variable nozzle mechanism based on sensor signals from a pressure sensor in the plasma heating chamber and a turbine inlet temperature sensor. The present configuration is characterized by the ability to automatically adjust the cross-sectional area and exhaust angle of the nozzle neck according to the plasma heating state, thereby enabling the real-time implementation of optimized exhaust characteristics for each operating condition, unlike a single-shape nozzle. The present configuration is significant in that it provides a closed-loop thrust control structure that controls the nozzle geometry by directly reflecting thermal fluid state quantities such as pressure and temperature.

[0126] This configuration effectively optimizes both thrust and fuel efficiency simultaneously by reducing or expanding the cross-sectional area of ​​the nozzle throat and adjusting the exhaust angle when chamber pressure and turbine inlet temperature change due to plasma heating. Under high-temperature and high-pressure conditions, this configuration enables dynamic response by adjusting the nozzle toward the expansion side to efficiently induce supersonic expansion, while adjusting it toward the contraction side to reduce thrust loss under low-load or low-temperature conditions. As a result, this configuration expands the performance map of the plasma jet engine across various flight conditions and operating modes, while improving overall propulsion efficiency and responsiveness.

[0128] The embodiments described above are combinations of the components and features of the present invention in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of the present invention by combining some components and / or features. The order of operations described in the embodiments of the invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that embodiments may be constructed by combining claims that do not have an explicit citation relationship in the claims, or that they may be included as new claims through amendments made after filing.

[0129] It will be apparent to those skilled in the art that the present invention may be embodied in other forms without departing from the technical spirit and essential features of the present invention. Accordingly, the above embodiments should be considered in all illustrative aspects rather than as a limiting one. The scope of the present invention shall be determined by a reasonable interpretation of the appended claims and all possible variations within the equivalent scope of the present invention.

Claims

Claim 1 A jet engine equipped with an electromagnetic wave-based plasma heating chamber, comprising: a compressor that inhales and compresses air; a plasma heating chamber that heats the compressed air supplied from the compressor by electromagnetic waves; and a turbine driven by the heated gas from the plasma heating chamber. The apparatus includes a nozzle for spraying gas that has passed through the turbine, and the plasma heating chamber comprises: (i) a double structure consisting of a metal-based outer casing and a dielectric-based inner liner coaxially arranged inside the outer casing, wherein the outer casing is configured to function as a Faraday cage by grounding and is configured to maintain electrical continuity in a path including the flange of the outer casing, a torch port adapter, and a shielding cover; (ii) a plasma torch, wherein the plasma torch is arranged in a circumferential tangential direction of the inner liner to form a rotational flow inside the inner liner; (iii) the inner liner is configured to include a quartz tube and be replaceable, and a spiral groove is formed on the inner surface of the inner liner to stabilize the rotational flow and suppress local energy concentration of the plasma or arc generation; (iv) an RF choke groove is formed around the torch port into which the plasma torch is inserted or coupled, and the torch port adapter and shielding cover are coupled through an electromagnetic shielding gasket to suppress electromagnetic leakage through the torch port; (v) A plasma jet engine comprising an optical sensor for measuring plasma emission light and a reflected power sensor for monitoring reflected power, and a power control unit configured to maintain the turbine inlet temperature within a target range by adjusting the output or frequency of electromagnetic waves based on the correlation between the sensor signals of the optical sensor and the reflected power sensor and the turbine inlet temperature, (vi) and a coupling portion between the plasma heating chamber and the turbine comprising a ceramic-based insulating ring and a metal bellows configured to absorb vibration or thermal expansion while reducing heat transfer. Claim 2 A plasma jet engine according to claim 1, wherein a backflow prevention structure and a flow control valve are disposed in the outlet duct of the compression section. Claim 3 A plasma jet engine according to claim 1, wherein a vibration isolation mount is disposed between the compression section and the plasma heating chamber. Claim 4 A plasma jet engine according to claim 1, wherein the plasma torch comprises a regenerative cooling type cooling channel configured such that a portion of compressed air branched from the outlet of the compression section passes through the interior of the plasma torch to cool the plasma torch and then is heated and introduced into the plasma heating chamber. Claim 5 A plasma jet engine according to claim 4, wherein the cooling channel further comprises a leak-prevention seal and a flow control means. Claim 6 A plasma jet engine according to claim 1, wherein the inner liner is formed of quartz or a high-heat-resistant ceramic material including aluminum nitride or boron nitride. Claim 7 A plasma jet engine according to claim 1, wherein electromagnetic energy generated from the plasma torch is transferred to the plasma heating chamber through a dedicated passage and then amplified to increase the electromagnetic field strength by resonance or coupling. Claim 8 A plasma jet engine according to claim 7, wherein the electromagnetic energy is transmitted to the plasma heating chamber in a combined manner of a waveguide and a resonator, or is radiated directly into the plasma heating chamber through an antenna. Claim 9 A plasma jet engine according to claim 1, configured to detect abnormal conditions including plasma extinction or instability in real time based on changes in reflected power measured by the reflected power sensor. Claim 10 A plasma jet engine according to claim 1, wherein the outer casing is further provided with at least one of a grounding lug, a cable routing bracket, or a lifting eye.

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