Axisymmetric adjustable nozzle adapting to characteristics of rotating detonation helical shock wave

Abstract

The application relates to a rotating detonation engine and relates to an axisymmetric adjustable nozzle suitable for rotating detonation spiral shock characteristics. The nozzle is composed of a fixed section, an air reservoir, a push rod, a connecting ring, a tractor, a contraction plate, an expansion inner plate, an expansion outer plate, a hook connecting piece and a thermoelectric conversion cover. The fixed section is a frame for the transition from a combustion chamber to a nozzle, and a hinged frame is arranged outside the fixed section for supporting the air reservoir. The air reservoir and the push rod adopt a structure similar to that of an injector. The air reservoir is hinged to the fixed section, and the push rod is hinged to the connecting ring. One end of the tractor is hinged to the connecting ring, and the other end of the tractor is hinged to the expansion outer plate, which is used for dragging the expansion outer plate to move. The expansion inner plate is hinged to the contraction plate. The thermoelectric conversion cover is a conical silicon-germanium alloy cover, which is used for absorbing waste heat of the nozzle and converting the waste heat into electric energy to provide energy for the whole adjustable nozzle. The relative airflow angle in front of the shock wave can be controlled within a proper range under various working conditions in a wide speed range, so that the shock wave angle can be controlled, and the oblique shock energy loss in the rotating detonation engine can be reduced.

Description

Technical Field

[0001] This invention relates to a rotary detonation engine, and more particularly to an axisymmetric adjustable nozzle adapted to the characteristics of rotary detonation spiral excitation. Background Technology

[0002] Detonation waves are combustion waves that propagate at supersonic speeds, and their combustion is intense and rapid. The generation of detonation waves is mainly due to the induction of shock waves, and their structure consists of a leading shock wave and a reaction zone. The reaction zone follows the leading shock wave zone, and through the compression of the leading shock wave, the reactants are heated and burned, releasing energy far exceeding that of ordinary combustion. Compared with isobaric combustion, the advantages of detonation combustion are mainly in self-pressurization, high heat release rate, and high thermal cycle efficiency, which can greatly reduce the complexity of the system (Driscoll R, George AS, Gutmark E J. Numerical investigation of injection within an axisymmetric rotating detonation engine[J]. International Journal of Hydrogen Energy,2016,41(3):2052-2063); therefore, detonation engines have become a popular research direction in the field of propulsion.

[0003] Silicon-germanium alloy is a widely used thermoelectric material under high temperature conditions. Its main advantages include high thermal stability, strong oxidation resistance, and high melting point (Cai Xingyu, Wang Zan. Research status of silicon-germanium thermoelectric materials [J]. Henan Science and Technology, 2019, No. 670(08): 140-141). Utilizing the Seebeck effect of semiconductors, that is, the PN junction formed by connecting P-type (hole) semiconductors and N-type (electron) semiconductors, one end is placed near a heat source to form a hot end, and the other end is placed near a cold source to form a cold end. The thermal excitation effect increases the concentration of holes and electrons at the hot end, and the holes and electrons diffuse from the hot end to the cold end, forming a potential difference. When a load is connected, current can be generated (Chen Y, Hou XN, Ma CY, et al. Review of Development Status of Bi2Te3-Based Semiconductor Themoelectric Power Generation [J]. Advances In Materials Science And Engineering, 2018(5): 150-169).

[0004] A thermoelectric conversion shroud made of silicon-germanium alloy can absorb waste heat from the nozzle and convert it into electrical energy under the Seebeck effect. The syringe-type gas storage chamber is a highly efficient water electrolysis device. Utilizing the electrical energy converted from waste heat, it can change the gas volume inside the storage chamber cavity through the reduction reaction of water electrolysis and the oxidation reaction of hydrogen, thereby providing power for the entire adjustable device, reducing energy consumption, and enabling the rotary detonation engine to operate efficiently.

[0005] A rotary detonation engine (RDE) operates on the principle of rotating detonation. Its thrust originates from detonation waves propagating continuously circumferentially within the annular combustion chamber. Energy losses in an RDE primarily include: oblique shock wave energy loss, gas friction loss, and mixing loss due to combustion exhaust entering the atmosphere. The most significant energy loss is oblique shock wave energy loss; therefore, minimizing this loss is crucial for fuel efficiency and can significantly improve engine efficiency.

[0006] The energy loss of oblique shock waves mainly includes two aspects: the energy loss that occurs when the flow field passes through the shock wave and the work done on the flow field during shock wave propagation. The shock wave angle and shock wave intensity are the main factors affecting the energy loss of oblique shock waves. The method adopted in this invention is to reduce the energy loss of oblique shock waves by adjusting the shock wave angle. In the nozzle, the shock wave angle and the relative airflow angle in front of the shock wave (i.e., the relative angle between the airflow and the direction of shock wave motion) show a high positive correlation and a certain causal relationship. Therefore, adjusting the relative airflow angle in front of the shock wave is a feasible way to adjust the shock wave angle. The axial distribution of the Mach number in the nozzle design and the shock wave propagation velocity are the determining factors of the relative airflow angle in front of the shock wave. This guides the design of the nozzle profile in this invention, that is, first study the optimal shock wave structure, calculate the Mach number distribution law in the corresponding nozzle, and then calculate the corresponding nozzle profile. Summary of the Invention

[0007] This invention aims to provide an axisymmetric adjustable nozzle that adapts to the characteristics of rotating detonation spiral shock waves. It can adjust the engine throat and exit area over a wide speed range, recover waste heat through a thermoelectric conversion device to provide electrical energy, and utilize the electrolysis and reduction reaction of water to provide power. This enables adaptive flow regulation of the nozzle, while controlling the relative airflow angle in front of the shock wave to keep it within a reasonable range, reducing energy loss caused by oblique shock waves, increasing thrust and reducing energy consumption, and improving the working efficiency of the rotating detonation engine.

[0008] The axisymmetric adjustable nozzle adapted to the characteristics of rotating detonation spiral shock waves consists of a fixed section, a gas storage chamber, push rods, a connecting ring, a traction device, a contraction plate, an inner expansion plate, an outer expansion plate, a hook plate, and a thermoelectric conversion cover. The fixed section is a frame that transitions from the combustion chamber to the nozzle. Four gas storage chambers are provided outside the fixed section, and four hinges are provided outside the fixed section to support the gas storage chambers. There are 24 contraction plates, and 24 slots are provided inside the fixed section to support the contraction plates and limit their displacement except axially. Four push rods are provided corresponding to the gas storage chambers. The gas storage chambers and push rods adopt a structure similar to an injector. Changes in the gas volume inside the gas storage chamber drive the push rods to move back and forth. The gas storage chamber is hinged to the fixed section. The push rod is hinged to the connecting ring; the connecting ring consists of two semi-circular rings, with a hinge frame on the connecting ring for hinged connection with the push rod and the traction device; one end of the traction device is hinged to the connecting ring, and the other end of the traction device is hinged to the expansion outer plate for traction of the expansion outer plate; there are 12 expansion inner plates, 12 expansion outer plates, and 24 hooking pieces; the expansion inner plate is hinged to the contraction plate, and both ends of the expansion inner plate and the expansion outer plate are provided with protruding cylinders, and the expansion inner plate and the expansion outer plate are connected by hooking pieces that hook the protruding cylinders of the expansion inner plate and the expansion outer plate respectively; the thermoelectric conversion cover is a conical silicon-germanium alloy cover for absorbing the waste heat of the nozzle and converting it into electrical energy to provide energy for the entire adjustable nozzle.

[0009] The expansion inner plate and the contraction plate are hinged together, and the two can rotate relative to each other within a certain angle range.

[0010] A through hole is provided at the connection between the shrink plate and the expansion plate, and the shrink plate and the expansion plate can be connected by a shaft so that they can rotate relative to each other;

[0011] The outer side of the expansion plate has a hinge seat, and the expansion plate is hinged to the traction device through the hinge seat.

[0012] The contraction plate, the inner expansion plate, and the outer expansion plate are metal plates with special profiles. These special profiles are designed based on the characteristics of rotational detonation accompanied by helical shock waves, in order to reduce the energy loss of oblique shock waves.

[0013] The gas storage chamber is in the form of an syringe outer cylinder, and the push rod is in the form of a syringe inner core. The gas storage chamber is a high-efficiency water electrolysis device, in which the electrolysis and reduction of water occur, which can change the volume of the gas in the cavity, thereby moving the push rod and realizing the operation of the adjustable device.

[0014] The thermoelectric conversion cover of this invention uses silicon-germanium alloy. Silicon-germanium alloy has the advantages of high thermal stability, strong oxidation resistance and high melting point. It is a widely used thermoelectric material in high-temperature areas. The silicon-germanium alloy thermoelectric conversion cover of this invention can convert the waste heat of the nozzle into electrical energy, and through a high-efficiency water electrolysis device, convert the electrical energy into the kinetic energy of the air, realizing the adaptive adjustment of the device and saving energy.

[0015] Addressing the primary energy loss factor in rotating detonation engines—the oblique shock wave—this invention, based on research findings on the helical characteristics of oblique shock waves, designs a nozzle profile that effectively reduces oblique shock wave energy loss. This special profile allows for control of the relative airflow angle before the shock wave within a suitable range under various operating conditions across a wide speed range, thereby controlling the shock wave angle and reducing oblique shock wave energy loss in rotating detonation engines. Simultaneously, the nozzle structure is adjustable, allowing for changes in the throat and exit area, enabling thrust adjustment under various operating conditions and improving the operating efficiency of the rotating detonation engine.

[0016] The technical innovations of this invention are as follows:

[0017] 1. The profiles of the contraction plate, expansion plate, and related components are designed based on the characteristics of rotational detonation accompanied by helical shock waves. This enables the nozzle to reduce oblique shock wave losses and achieve energy management, which can adjust the throat and exit area while keeping the engine at a low energy loss.

[0018] 2. The thermoelectric conversion cover installed outside the nozzle is made of high-temperature resistant silicon-germanium alloy, which can absorb most of the waste heat of the nozzle and convert it into electrical energy to achieve adaptive adjustment of the nozzle.

[0019] 3. The gas storage chamber and push rod are in the form of a syringe and are equipped with a highly efficient water electrolysis device. The electrolysis reaction of water and the oxidation reaction of hydrogen are used to change the volume of the gas in the cavity and provide thrust.

[0020] 4. The electrical energy generated by the thermoelectric conversion hood is directly or indirectly supplied to the gas storage chamber to provide energy for the electrolysis reaction of water.

[0021] Compared with traditional adjustable nozzles, the present invention has the following advantages:

[0022] (1) Energy saving: The thermoelectric conversion cover can convert some of the waste heat of the nozzle that cannot provide thrust into electrical energy, and then convert it into power through the water electrolysis device to provide power for the entire adjustable device, so as to realize the adaptive adjustment of the nozzle and save additional energy input; in addition, the special shape can also minimize the loss of oblique shock wave, further reducing energy consumption.

[0023] (2) The design is novel. The special contraction and expansion plate profiles designed based on the motion law of the spiral oblique shock wave can maintain a relatively ideal relative airflow angle in front of the shock wave while adjusting the throat area and outlet area to obtain greater thrust, thereby achieving energy management and reducing the energy loss caused by the oblique shock wave.

[0024] (3) It has a wide working range and can adjust the engine throat and outlet area in a wide speed range to achieve efficient engine operation. Attached Figure Description

[0025] Figure 1This is a schematic diagram of the overall structure of the present invention (with thermoelectric conversion cover);

[0026] Figure 2 This is a schematic diagram of the overall structure of the present invention (without the thermoelectric conversion cover);

[0027] Figure 3 This is a schematic diagram of the shrink plate and expansion inner plate structure of the present invention;

[0028] Figure 4 This is a schematic diagram of the shrink plate and expansion plate structure of the present invention;

[0029] Figure 5 The curves show the variation of the relative airflow angle and shock wave angle at the inner wall of the nozzle.

[0030] Figure 6 This is a schematic diagram of the gas storage chamber and push rod of the present invention.

[0031] Among them, 1 is the fixed section, 2 is the gas storage chamber, 3 is the push rod, 4 is the connecting ring, 5 is the traction device, 6 is the shrink plate, 7 is the expansion inner plate, 8 is the expansion outer plate, 9 is the hook plate, and 10 is the thermoelectric conversion cover. Detailed Implementation

[0032] The preferred embodiments of the present invention will be further described below with reference to the accompanying drawings. The preferred embodiments described herein are for illustration and explanation only, and are not intended to limit the present invention.

[0033] See Figure 1 and 2 This embodiment provides an axisymmetric adjustable nozzle adapted to the characteristics of rotating detonation spiral excitation, including a fixed section 1, four gas storage chambers 2, four push rods 3, a connecting ring 4, a traction device 5, 24 contraction plates 6, 12 expansion inner plates 7, 12 expansion outer plates 8, a hook plate 9, and a thermoelectric conversion outer cover 10.

[0034] The fixed section 1 is a frame that transitions from the combustion chamber to the nozzle. The fixed section has 24 slots inside to support the contraction plate 6; the fixed section has 4 hinges at its ends (see reference). Figure 1 (Enlarged view) This supports the gas storage chamber. The gas storage chamber 2 and push rod 3 are similar to those in a syringe. Changes in the gas volume within the gas storage chamber 2 push the push rod 3 back and forth. The bottom of the gas storage chamber 2 is hinged to the end of the fixed section 1, and the push rod 3 is hinged to the connecting ring 4. The connecting ring 4 consists of two semi-circular rings, and a hinge frame is provided on the connecting ring 4 (see reference). Figure 2 (Enlarged view), used for hinged connection with push rod 3 and traction device 5; the traction device 5 has a connecting ring hinged at one end and an expansion outer plate hinged at the other end, used for traction of expansion outer plate movement; the thermoelectric conversion cover 10 is a conical silicon-germanium alloy cover used to absorb the waste heat of the nozzle and convert it into electrical energy to provide energy for the entire adjustable device.

[0035] See Figure 3 The contraction plate 6 and the expansion inner plate 7 are metal plates with special profiles. The Mach number distribution of the nozzle with this profile can minimize the energy loss of the oblique shock wave. The contraction plate 6 and the expansion inner plate 7 are hinged and can rotate relative to each other within a certain angle range (generally about 30° to 60°). The expansion inner plate 7 has protruding cylinders at both ends, which can be connected to the expansion outer plate through hook plates.

[0036] See Figure 4 The contraction plate 6 and the expansion outer plate 8 are metal plates with special profiles, which minimize the oblique shock wave loss of the adjustable nozzle at various Mach numbers. There is a through hole at the connection between the contraction plate 6 and the expansion outer plate 8, which can be connected by a shaft, allowing them to rotate relative to each other. There are protruding cylinders at both ends of the expansion outer plate 8, which can be connected to the expansion inner plate through hook plates. There is a hinge seat on the outer side of the expansion outer plate for hinge connection with the traction device.

[0037] See Figure 5 The curves showing the variation of the relative airflow angle and shock wave angle at the inner wall of the nozzle are shown. The shock wave angle (circumferential section) of the nozzle increases with the increase of the relative airflow angle (the angle of airflow relative to the shock wave motion). Therefore, the relative airflow angle is an important factor in determining the shock wave angle. Based on this principle, the special profiles of the contraction plate 6, the expansion inner plate 7, and the expansion outer plate 8 are designed.

[0038] See Figure 6 The gas storage chamber 2 is in the form of an syringe outer cylinder, and the push rod 3 is in the form of a syringe inner core. The gas storage chamber 2 is actually a high-efficiency water electrolysis device, in which the electrolysis and reduction reactions of water occur, which can change the volume of the air cavity, thereby moving the push rod 3 and realizing the operation of the adjustable device; the electrical energy generated by the thermoelectric conversion cover is used to electrolyze the water in the gas storage chamber.

[0039] The working principle of this invention: The thermoelectric conversion cover 10 is made of silicon-germanium alloy and can convert the waste heat of the nozzle into electrical energy through the thermoelectric conversion effect. The electrical energy is collected and stored in a battery as the driving energy for the adjustable device. The syringe-type gas storage chamber 2 is a high-efficiency water electrolysis device, used to carry out the electrolysis and reduction reaction of water within it. It can change the gas volume in the cavity. As the gas volume changes, the push rod 3 is displaced inward or outward. The push rod 3 drives the connecting ring 4, which drives the traction device 5, pulling the contraction plate 6, the inner expansion plate 7, and the outer expansion plate 8 to achieve adjustment, thereby changing the throat and outlet area. When the water in the gas storage chamber 2 undergoes an electrolysis reaction to generate oxygen and hydrogen, it pushes the push rod 3 outward, and the contraction plate 6 and the inner expansion plate 7 and the outer expansion plate 8 expand outward, increasing the nozzle throat and outlet area. When the hydrogen in the gas storage chamber 2 undergoes an oxidation reaction to generate water, it causes the push rod 3 to move inward, and the contraction plate 6 and the inner expansion plate 7 and the outer expansion plate 8 contract inward, decreasing the nozzle throat and outlet area. The fixed section has slots inside, which can be used to form a contraction plate 6. The expansion inner plate 7 and expansion outer plate 8 are connected by hook pieces 9. The contraction plate 6, the expansion inner plate 7, and the expansion outer plate 8 are all designed to adapt to the characteristics of rotating detonation accompanied by spiral shock waves, effectively reducing the energy loss of the oblique shock wave and the engine energy consumption, thus achieving efficient operation of the rotating detonation engine. The intensity of the oblique shock wave is highly correlated with the relative airflow angle in front of the shock wave, so the intensity of the oblique shock wave can be adjusted by adjusting the relative airflow angle in front of the shock wave, thereby reducing the energy loss it causes. Therefore, this invention achieves wide-range speed range adjustment of the throat and outlet area while rationally managing energy and reducing engine energy consumption.

[0040] In summary, this invention can adjust the throat and outlet area of ​​a rotating detonation engine over a wide speed range, thereby regulating the engine flow rate. It can also maintain the relative airflow angle in front of the shock wave within a suitable range, reducing energy loss caused by oblique shock waves, increasing thrust, and reducing energy consumption. At the same time, the silicon-germanium alloy thermoelectric conversion device can convert nozzle waste heat into electrical energy, increasing the power of the entire device and further reducing energy consumption, thereby improving the performance of the rotating detonation engine.

Claims

1. An axisymmetric adjustable nozzle adapted to the characteristics of rotating detonation spiral shock waves, characterized in that... It consists of a fixed section, a gas storage chamber, push rods, a connecting ring, a traction device, a contraction plate, an inner expansion plate, an outer expansion plate, a hook plate, and a thermoelectric conversion cover. The fixed section is a frame that transitions from the combustion chamber to the nozzle. Four gas storage chambers are provided outside the fixed section, and four hinges are provided on the outside of the fixed section to support the gas storage chambers. There are 24 contraction plates, and 24 slots are provided inside the fixed section to support the contraction plates and restrict their displacement except axially. Four push rods are provided corresponding to the gas storage chambers. The gas storage chambers and push rods adopt a structure similar to an injector. Changes in the gas volume inside the gas storage chamber push the push rods to move back and forth. The gas storage chamber is hinged to the fixed section, and the push rods are hinged to the connecting ring. The connecting ring consists of two semi-circular rings with a hinge for hinged connection to the push rod and the traction device. One end of the traction device is hinged to the connecting ring, and the other end is hinged to the expansion outer plate for moving the expansion outer plate. There are 12 expansion inner plates, 12 expansion outer plates, and 24 hooking pieces. The expansion inner plate is hinged to the contraction plate. Both ends of the expansion inner plate and the expansion outer plate have protruding cylinders. The expansion inner plate and the expansion outer plate are connected by hooking pieces that hook the protruding cylinders of the expansion inner plate and the expansion outer plate at their respective ends. The thermoelectric conversion cover is a conical silicon-germanium alloy cover for absorbing waste heat from the nozzle and converting it into electrical energy to provide power for the entire adjustable nozzle. The inner expansion plate and the outer expansion plate are hinged together, and the two can rotate relative to each other within an angle range of 30 to 60 degrees. The outer expansion plate, the inner expansion plate, and the outer expansion plate are metal plates with special profiles. The special profiles are designed based on the characteristics of rotational detonation accompanied by helical shock waves in order to reduce the energy loss of oblique shock waves.

2. The axisymmetric adjustable nozzle adapted to the characteristics of rotating detonation spiral shock waves as described in claim 1, characterized in that... The connection between the shrink plate and the expansion plate is provided with a through hole, and the shrink plate and the expansion plate can be connected by a shaft so that they can rotate relative to each other.

3. The axisymmetric adjustable nozzle adapted to the characteristics of rotating detonation spiral shock waves as described in claim 1, characterized in that... The outer side of the expansion plate has a hinge seat, and the expansion plate is hinged to the traction device through the hinge seat.

4. The axisymmetric adjustable nozzle adapted to the characteristics of rotating detonation spiral shock waves as described in claim 1, characterized in that... The gas storage chamber is in the form of an syringe outer cylinder, and the push rod is in the form of a syringe inner core. The gas storage chamber is a high-efficiency water electrolysis device, which is used to carry out the electrolysis and reduction reaction of water inside, change the volume of the gas in the cavity, thereby moving the push rod and realizing the operation of the adjustable device.

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