Parallel adjustable nozzle for combined power system and method of controlling the same

Abstract

The application discloses a parallel adjustable nozzle for a combined power system and a control method thereof. The parallel adjustable nozzle comprises an outer shell, a first flow channel, a second flow channel and an adjustable flow channel. The second flow channel is located between the outer shell and the first flow channel. The adjustable flow channel comprises fish scale adjusting pieces arranged in a circumferential direction. The first end of the fish scale adjusting pieces is hinged to the outlet edge of the first flow channel. In the contraction state, the leading edge of the fish scale adjusting pieces is folded towards the axis of the first flow channel, and the outer contour of the fish scale adjusting pieces is located on the inner side of the radial section of the second flow channel outlet, i.e. the second flow channel is completely exposed. In the expansion state, the leading edge of the fish scale adjusting pieces is opened away from the axis of the first flow channel, and the tail end of the fish scale adjusting pieces extends to the inner wall of the outer shell to shield the second flow channel. The application is applied to the technical field of propulsion and solves the engineering problems of the self-adaptation of the nozzle geometry, the exposed aerodynamic resistance of the auxiliary flow channel and the reliability of mode switching of the existing combined power system in the parallel configuration.

Description

Technical Field

[0001] This invention relates to the field of aerospace propulsion technology, specifically to a parallel adjustable nozzle for a combined propulsion system and its control method, and more particularly to an adjustable nozzle with an axisymmetric fish-scale configuration that can simultaneously achieve adjustment of the main flow channel exit area and switching of circumferential flow channel shielding / exposure functions. Background Technology

[0002] A combined propulsion system is a propulsion system that organically combines multiple power sources. It can provide efficient thrust over a wide speed range and is one of the core propulsion solutions for future hypersonic vehicles, two-stage-to-orbit vehicles, and rapid-response space entry systems. The operating mode of a combined propulsion system is usually divided into multiple stages: at low speeds, it relies on auxiliary power to provide thrust, and at high speeds, it relies on the main power to provide thrust.

[0003] Traditional combined propulsion systems typically employ a series configuration where multiple power sources share a common internal flow channel: the auxiliary power source is installed inside the main flow channel, and the two working fluids mix in the common channel before being discharged through a single exhaust nozzle. This configuration offers the advantage of compactness, but it suffers from several insurmountable drawbacks: First, the shared internal flow channel makes parameter matching between the two airflows difficult; when airflows with significantly different total temperatures and pressures mix in the same channel, severe mixing losses occur, resulting in a marked decrease in thrust performance. Second, the high-temperature, high-speed jet from the auxiliary power source strongly interferes with the flow field structure of the main flow channel, easily leading to inability to start the intake or unstable combustion during mode switching, resulting in poor switching reliability. Third, the geometry of the shared flow channel needs to accommodate the design requirements of multiple operating modes, making it impossible for a fixed-geometry nozzle to simultaneously meet the optimal expansion ratio requirements of each mode across a wide velocity range.

[0004] To address these issues, a parallel configuration was proposed, where multiple power sources each have their own independent flow channels, exhaust separately, and do not interfere with each other. However, the parallel configuration faces a new engineering challenge: at low Mach numbers, the auxiliary power source needs to be exposed to provide thrust, while the main nozzle requires a smaller exit area to ensure sufficient airflow expansion; at high Mach numbers, the main power source operates independently, and the auxiliary power source is shut off, but its exposed flow channel outlet generates significant bottom drag and aerodynamic heating under the impact of high-speed airflow. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a parallel adjustable nozzle for a combined power system and its control method, solving the engineering challenges of nozzle geometric adaptation in different working modes, aerodynamic drag of exposed auxiliary flow channels, and reliability of mode switching in existing combined power systems under parallel configuration. While achieving continuous adjustment of the main flow channel outlet area, it also has the mode switching function of circumferential flow channel outlet obstruction / exposure.

[0006] To achieve the above objectives, the present invention provides a parallel adjustable nozzle for a combined power system, comprising an outer shell, a first flow channel, a second flow channel, and an adjustable flow channel; The first flow channel is coaxially disposed inside the outer shell, and the second flow channel is located between the outer shell and the first flow channel, with each of the second flow channels spaced circumferentially around the first flow channel; The outlet of the second flow channel is located downstream of the outlet of the first flow channel. The adjustable flow channel includes a plurality of fish scale adjustment plates arranged circumferentially, and the first end of each fish scale adjustment plate is hinged to the outlet edge of the first flow channel. The adjustable flow channel has a contraction state and an expansion state: In the contracted state, the leading edge of each of the fish scale adjustment plates converges toward the axis of the first flow channel, and the outer contour of the fish scale adjustment plate is located radially inside the outlet section of the second flow channel, that is, the second flow channel is completely exposed. In the expanded state, the leading edge of each of the fish scale adjustment plates opens away from the axis of the first flow channel, and the tail end of each fish scale adjustment plate extends to the inner wall of the outer shell, blocking the second flow channel.

[0007] In one embodiment, the number of fish scale adjustment plates satisfy ,and It is an even number; The axial projection length of each of the fish scale adjustment plates The diameter of the tail end of the outer shell The ratio satisfies Furthermore, the axial distance between the hinge axis of the fish-scale adjusting plate and the outlet section of the first flow channel is not greater than [missing information]. ; The inner wall surface of each of the fish scale adjustment plates forms a continuously adjustable axisymmetric gradually expanding surface between the contracted state and the expanded state, and the circumferential overlap width between two adjacent fish scale adjustment plates in the expanded state is not less than 5% of the circumferential width of the fish scale adjustment plate.

[0008] In one embodiment, the number of the second flow channels satisfy And the M second flow channels are evenly distributed along the circumferential direction at equal angular intervals of 360° / M; The outlet cross-sectional diameter of the second flow channel is The radial distance between the center of the outlet section of the second flow channel and the axis of the first flow channel is... ,satisfy: , , ; The axial distance between the axial position of the second flow channel outlet section and the axial position of the first flow channel outlet section satisfy .

[0009] In one embodiment, the outlet cross-sectional area of ​​the adjustable flow channel in the contracted state is [missing information]. The outlet cross-sectional area of ​​the adjustable flow channel in the expanded state is ,and ; The minimum outlet diameter of the adjustable flow channel in the contracted state satisfy ,in The outlet diameter of the first flow channel.

[0010] In one embodiment, a high-temperature flexible sealing structure is provided on the overlapping surface between two adjacent fish scale adjustment plates, and the high-temperature flexible sealing structure adopts an overlapping labyrinth seal. In the expanded state, a metal O-ring is provided between the tail end of the adjustable flow channel and the inner wall of the outer casing.

[0011] In one embodiment, the parallel adjustable nozzle further includes a drive device comprising a plurality of hydraulically actuated cylinders evenly arranged circumferentially. Each of the hydraulic actuators achieves the synchronous extension and retraction of all the fish scale adjustment plates through a mechanical synchronous linkage mechanism or an electro-hydraulic servo synchronous circuit.

[0012] In one embodiment, an annular heat-insulating baffle is provided between the first flow channel and each of the second flow channels. The annular heat-insulating baffle has a multi-layer structure, including an inner thermal barrier coating, a middle aerogel heat-insulating felt or vacuum interlayer, and an outer heat-resistant alloy support shell.

[0013] To achieve the above objectives, the present invention also provides a control method applied to a parallel adjustable nozzle for a combined propulsion system as described above. The parallel adjustable nozzle is mounted on an aircraft. The combined propulsion system on the aircraft includes a first thrust unit and a plurality of second thrust units corresponding one-to-one with second flow channels. The thrust outlet of the first thrust unit is connected to the inlet of the first flow channel, and the thrust outlet of the second thrust unit is connected to the inlet of the corresponding second flow channel. The control method includes the following steps: Step 1: Obtain the current Mach number of the aircraft. ; Step 2: Based on the current flight Mach number Calculate the target outlet area of ​​the adjustable flow channel according to the preset control law. ; Step 3: Based on the target outlet area of ​​the adjustable flow channel Compared with actual export area The error between them generates a drive control signal, which adjusts the radial position of the fish scale adjustment plate to change the outlet area.

[0014] In one embodiment, the target export area The calculation process is as follows: when At that time, the target export area or ,in, The lowest Mach number at which the first thrust unit can operate independently. The outlet cross-sectional area of ​​the adjustable flow channel in the contracted state; when At that time, the target exit area is calculated based on the area-Mach number interpolation curve. : ; in, This refers to the outlet cross-sectional area of ​​the adjustable flow channel in the expansion state. It is a power exponent; when At that time, the target export area or ,in, This is the design point Mach number for the first thrust unit.

[0015] In one embodiment, when the aircraft's flight Mach number exceeds a preset lower threshold and the actual outlet area of ​​the adjustable flow channel exceeds a preset transition threshold, a second thrust unit shutdown transition procedure is initiated, including: Gradually increase the outlet area of ​​the adjustable flow channel, and at the same time gradually reduce the propellant supply flow rate of the second thrust unit according to the attenuation curve. After the adjustable flow channel reaches the expansion state, delay for a preset time, and then shut off the propellant supply of the second thrust unit to complete the mode switch. The attenuation curve is specifically as follows: ; in, , The thrust of the second thrust unit before and after attenuation. This is the decay index.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: 1. This invention expands the function of the adjustable flow channel from a single outlet area adjustment to simultaneously perform two functions: area adjustment of the first flow channel and blocking / exposing mode switching of the second flow channel. The second flow channel is exposed when needed and protected by the adjustable flow channel when not needed, thus avoiding bottom resistance and aerodynamic heating caused by high-speed airflow. 2. The present invention adopts a design of parallel connection of the first flow channel and the second flow channel, which fundamentally solves the problems of large mixing loss and severe mutual interference of the two airflows in the series configuration; 3. This invention achieves a seamless and smooth transition from low-speed mode to high-speed mode through the coordinated design of area-Mach number interpolation curve and thrust decay curve, eliminating the thrust gap and discontinuity problems in the mode switching of traditional combined propulsion systems. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is an isometric view of the parallel adjustable nozzle in the adjustable flow channel contraction state in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the parallel adjustable nozzle in the adjustable flow channel contraction state in an embodiment of the present invention; Figure 3 This is an isometric view of the parallel adjustable nozzle in the adjustable flow channel expansion state in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the parallel adjustable nozzle in the adjustable flow channel expansion state in an embodiment of the present invention; Figure 5 This is a partial structural diagram of the adjustable flow channel in an embodiment of the present invention; Figure 6 This is a schematic diagram of the drive structure of the adjustable flow channel in an embodiment of the present invention.

[0019] Reference numerals: 1. Outer shell; 2. First flow channel; 3. Second flow channel; 4. Adjustable flow channel; 401. Fish scale adjustment plate; 402. Hinge; 5. Hydraulic actuator; 6. Synchronous ring; 7. Linkage mechanism.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0026] Example 1 like Figures 1 to 4 The diagram shows a parallel adjustable nozzle (hereinafter referred to as "parallel adjustable nozzle") for a combined power system disclosed in this embodiment. It mainly includes an outer casing 1, a first flow channel 2, a second flow channel 3, and an adjustable flow channel 4. The outer casing 1, the first flow channel 2, and the second flow channel 3 are all rotating structures. The first flow channel 2 is coaxially disposed inside the outer casing 1. The second flow channels 3 are located between the outer casing 1 and the first flow channel 2, and each second flow channel 3 is circumferentially spaced around the first flow channel 2. The outlet of the second flow channel 3 is located downstream of the outlet of the first flow channel 2, that is, the outlet of the second flow channel 3 is positioned rearward relative to the outlet of the first flow channel 2. (Reference) Figure 5 The adjustable flow channel 4 includes a plurality of fish-scale adjustment plates 401 arranged circumferentially. The first end of each fish-scale adjustment plate 401 is hinged to the outlet edge of the first flow channel 2 by a hinge 402, and the adjustable flow channel 4 has a contracted state and an expanded state. In the contracted state, the leading edges of each fish-scale adjusting plate 401 converge toward the axis of the first flow channel 2, and the outer contour of the fish-scale adjusting plate 401 is located radially inside the outlet section of the second flow channel 3, that is, the second flow channel 3 is completely exposed. Figure 1 , Figure 2 As shown; In the expanded state, the leading edges of each fish-scale adjustment plate 401 open away from the axis of the first flow channel 2, and the tail ends of the fish-scale adjustment plates 401 extend to the inner wall of the outer shell 1, blocking the second flow channel 3, i.e. Figure 3 , Figure 4 As shown.

[0027] In this embodiment, by setting up a first flow channel 2 and a second flow channel 3 in parallel, which are respectively connected to the first thrust unit and the second thrust unit in the combined power system, the two flow and combustion processes can be completed without interference, fundamentally solving the problems of large mixing losses and severe mutual interference between the two airflows in the series configuration. On this basis, this embodiment expands the function of the adjustable flow channel 4 from a single outlet area adjustment to simultaneously undertake the functions of adjusting the area of ​​the first flow channel 2 and switching the shielding / exposed mode of the second flow channel 3. This allows the second flow channel 3 to operate exposed when needed and shielded and protected by the adjustable flow channel 4 when not needed, avoiding bottom resistance and aerodynamic heating caused by high-speed airflow scouring.

[0028] In this embodiment, the diameter of the tail end of the outer shell 1 is... The axial distance between the outlet of the first flow channel 2 and the tail end of the outer casing 1 is 600 mm. The first flow channel 2 includes a thrust chamber outlet section and an annular convergent-expanding transition section connected in series. In application, the inlet of the thrust chamber outlet section is connected to the first thrust unit, and the outlet of the annular convergent-expanding transition section is connected to the adjustable flow channel 4. The axial length of the thrust chamber outlet section is approximately 250 mm, the inlet diameter is 320 mm, and the outlet diameter is... satisfy ,For example Throat area of ​​the annular convergent-expanding transition segment. With entrance area satisfy For example, the throat diameter of the annular convergence-expansion transition section can be set to 170 mm, i.e. .

[0029] In this embodiment, the number of fish scale adjustment plates 401 satisfy ,and Even number; axial projection length of each fish scale adjustment piece 401 Diameter of the tail end of the outer shell 1 The ratio satisfies Furthermore, the axial distance between the hinge axis of the fish scale adjusting plate 401 and the outlet section of the first flow channel 2 is not greater than [missing information]. The inner wall surface of each fish scale adjustment piece 401 forms a continuously adjustable axisymmetric gradually expanding surface between the contracted state and the expanded state, and the circumferential overlap width between two adjacent fish scale adjustment pieces 401 in the expanded state is not less than 5% of the circumferential width of the fish scale adjustment piece 401.

[0030] For example, adjustable flow channel 4 can be... It consists of fish scale adjustment plates 401, and the axial projection length of each fish scale adjustment plate 401 is... The axial distance between the hinge axis of the fish-scale adjusting plate 401 and the outlet section of the first flow channel 2 is 18mm~22mm. In the expanded state, the trailing edges of the 12 fish-scale adjusting plates 401 open to the inner edge of the outer shell, and at this time, the radial radius of the outer contour of each fish-scale adjusting plate 401 is approximately 248mm (slightly less than 248mm). (With an installation gap), the circumferential overlap width between two adjacent fish-scale adjusting plates 401 is approximately 8% of the circumferential width of the fish-scale adjusting plate 401, ensuring the circumferential airtight continuity of the nozzle exit profile. In the contracted state, the trailing edges of the 12 fish-scale adjusting plates 401 converge towards the axis of the first flow channel 2, with a minimum exit diameter. satisfy ,For example .

[0031] In a preferred embodiment, a high-temperature flexible sealing structure is provided on the overlapping surface between two adjacent fish-scale adjusting plates 401, and the high-temperature flexible sealing structure adopts an overlapping labyrinth seal. For example, a multi-layer (e.g., 3-layer) graphite-based woven flexible sealing strip is connected between two adjacent fish-scale adjusting plates 401. The sealing strip has a temperature resistance of not less than 1200K and is used to continuously compensate for the relative sliding and deformation between the fish-scale adjusting plates 401 throughout the entire stroke, preventing high-temperature gas from leaking from the gaps between the plates.

[0032] In this embodiment, in the expanded state, there is a radial gap of no more than 1 mm between the tail end of the adjustable flow channel 4 and the inner wall of the outer casing 1. A metal O-ring is installed in this radial gap to prevent residual combustion gas blocked after the second thrust unit is shut down from flowing back into the interior. The metal O-ring can be made of Inconel 718 material, and its wall thickness can be designed to be 0.3 mm. In application, the metal O-ring can be directly fixed on the inner wall of the outer casing 1, and the adjustable flow channel 4 is in contact with the inner ring face of the metal O-ring in the expanded state.

[0033] In this embodiment, the number of second flow channels 3 satisfy Furthermore, the M second flow channels 3 are uniformly distributed along the circumference at equal angular intervals of 360° / M; the outlet cross-sectional diameter of the second flow channel 3 is... The radial distance between the center of the outlet section of the second flow channel 3 and the axis of the first flow channel 2 is... ,satisfy: , , The axial distance between the axial position of the outlet section of the second flow channel 3 and the outlet section of the first flow channel 2. satisfy .

[0034] For example, evenly arranged around the first flow channel 2 circumferentially There is one second flow channel 3, and the circumferential angular spacing between adjacent second flow channels 3 is 60°. The outlet diameter of the second flow channel 3 is... The radial distance between the center of the outlet section of the second flow channel 3 and the axis of the first flow channel 2 That is, the second flow channel 3 is located in the outer ring region of the tail section of the outer shell 1. The circumferential occupancy ratio of the six rocket nozzle outlets is... The axial distance between the axial position of the outlet section of the second flow channel 3 and the outlet section of the first flow channel 2 .

[0035] In this embodiment, the outlet cross-sectional area of ​​the adjustable flow channel 4 in the contracted state is: The outlet cross-sectional area of ​​the adjustable flow channel 4 in the expansion state is ,and For example, it can be designed as , , The minimum outlet diameter of adjustable flow channel 4 in the contracted state. satisfy That is, the outlet diameter of the adjustable flow channel 4 in the contracted state is basically the same as the outlet diameter of the first flow channel 2, so that the gas in the first flow channel 2 flows out of the adjustable flow channel 4 with an approximately equal cross section, avoiding backflow caused by excessive contraction.

[0036] The parallel adjustable nozzle in this embodiment also includes a driving device, which includes a plurality of hydraulic actuators 5 evenly arranged in the circumferential direction; each hydraulic actuator 5 realizes the synchronous extension and retraction of all fish scale adjustment plates 401 through a mechanical synchronous linkage mechanism or an electro-hydraulic servo synchronous circuit.

[0037] Figure 6The hydraulic actuators 5 shown are synchronized in retraction and extension of all fish-scale adjusting plates 401 via a mechanical synchronous linkage mechanism. This mechanism includes a synchronous ring 6 and corresponding linkage mechanisms 7. The synchronous ring 6 is located between the first flow channel 2 and the second flow channel 3, with its first end connected to the extension / retraction end of each hydraulic actuator 5. The first end of each linkage mechanism 7 is hinged to the second end of the synchronous ring 6, and the second end of each linkage mechanism 7 is hinged to the outer wall of the corresponding fish-scale adjusting plate 401. All hydraulic actuators 5 have their supply and return oil lines connected in parallel to the same hydraulic oil source with a supply pressure of 21 MPa. An electro-hydraulic servo valve is used for independent closed-loop control of the flow rate of each hydraulic actuator 5. The radial synchronous displacement of all fish-scale adjusting plates 401 is achieved through the servo valve's flow synchronization control loop, maintaining a radial displacement difference of less than 0.5 mm between any two fish-scale adjusting plates 401. The hydraulic actuator 5 has a stroke of approximately 120 mm, a maximum thrust of 8 kN per cylinder, and the adjustable flow channel 4 takes approximately 0.72 s to complete its full stroke from the contracted state to the expanded state. Preferably, each fish-scale adjustment plate 401 is equipped with an LVDT (Linear Variable Differential Transformer) displacement sensor with a resolution of 0.02 mm and a radial position control accuracy of ±0.2 mm.

[0038] In the specific implementation process, an annular heat insulation baffle is provided between the first flow channel 2 and each of the second flow channels 3. The annular heat insulation baffle has a multi-layer structure with a thickness of 3mm to 8mm, including an inner thermal barrier coating (e.g., a ceramic coating, 0.4mm thick), a middle aerogel heat insulation felt or vacuum interlayer (e.g., aerogel heat insulation felt, 5mm thick, thermal conductivity 0.038W / (m·K)), and an outer heat-resistant alloy support shell (e.g., a GH4169 support shell, 2.5mm thick). The annular heat insulation baffle effectively isolates the high temperature (up to 2000K to 2800K) on the side of the first flow channel 2 from the relatively low temperature (approximately 800K to 1200K) on the side of the second flow channel 3, preventing the hot backflow of the combustion gas in the first flow channel 2 from damaging the second flow channel 3 and the second thrust unit, while also preventing the exhaust flame of the second thrust unit from adversely interfering with the flow field inside the adjustable flow channel 4 during operation.

[0039] In this embodiment, the substrate material of the fish-scale regulating plate 401 is GH4169 (Inconel 718) nickel-based high-temperature alloy plate with a thickness of 3.5 mm. The inner wall surface of the gas-side is coated with a double-layer thermal barrier coating (TBC) using atmospheric plasma spraying (APS) process: the bonding layer is NiCoCrAlY (nickel-cobalt-chromium-aluminum-yttrium alloy, thickness 0.12 mm), the ceramic layer is 8YSZ (8% yttrium oxide-stabilized zirconium oxide, thickness 0.40 mm), the total TBC thickness is 0.52 mm, and the bonding strength is ≥28 MPa. The back side (non-gas-fuel side) of the fish-scale regulating plate 401 is processed with parallel radiative heat dissipation fins with a height of 3 mm and a spacing of 5 mm. Under the maximum heat load condition (Ma=4.5, total gas temperature approximately 1800 K), through the combined effect of TBC insulation and back-side radiative heat dissipation, the temperature of the substrate metal is maintained below 1050 K. The hinge pin of the fish-scale adjusting plate 401 uses a GH4169 substrate with a TiAlN (titanium aluminum nitride) coating. Its surface friction coefficient is approximately 0.12, and its designed fatigue life is 5 × 10⁻⁶ days. 4 The cycle of receiving and releasing continues.

[0040] Example 2 Based on the parallel adjustable nozzle in Embodiment 1, this embodiment discloses a corresponding control method. In application, the parallel adjustable nozzle is installed on an aircraft. The combined propulsion system on the aircraft includes a first thrust unit (e.g., a ramjet engine) and several second thrust units (e.g., rocket engines) corresponding one-to-one with the second flow channels. The thrust outlet of the first thrust unit is connected to the inlet of the first flow channel, and the thrust outlet of the second thrust unit is connected to the inlet of the corresponding second flow channel.

[0041] The control method in this embodiment mainly includes the following steps: Step 1: Obtain the current Mach number of the aircraft. For example, obtaining the aircraft's flight Mach number through the Airborne Air Data System (FADS). The data is transmitted to the FADEC control unit in real time at a refresh rate of 100Hz; Step 2: Based on the current flight Mach number Calculate the target outlet area of ​​the adjustable flow channel according to the preset control law. , specifically: when At this time, it enters the second thrust unit dominant mode, that is, the second flow channel is exposed, and the second thrust provides all or most of the thrust. At this time, the target exit area is... or (For example and The absolute value of the difference is less than a set threshold, where, The lowest Mach number at which the first thrust unit can operate independently, typically Ma1.5 to Ma2.5; when When entering transition mode, the adjustable flow channel outlet area changes accordingly. The area increases monotonically with the increase of the area-Mach number interpolation curve. The target exit area is then calculated based on this curve. ,in This is the design point Mach number for the first thrust unit, typically ranging from Ma3.0 to Ma5.0.

[0042] when At that time, it enters the first thrust unit dominant mode, with a target exit area. or (For example and When the absolute value of the difference is less than the set threshold, the adjustable flow channel maintains the expansion state, the second flow channel is completely blocked, and the first thrust unit independently provides all the thrust. Step 3: Based on the target outlet area of ​​the adjustable flow channel Compared with actual export area The error between them generates a drive control signal to adjust the radial position of the fish scale adjustment plate to change the outlet area, specifically: The FADEC control unit will target the export area. Converted to the corresponding radial target displacement of the fish scale adjustment plate The actual radial displacement fed back by the LVDT sensor Compare; The position PID controller outputs the control current of the electro-hydraulic servo valve to drive the hydraulic actuator cylinder to move. During the adjustment process, the FADEC control unit continuously monitors the radial displacement deviation of all fish scale adjustment plates. If the deviation exceeds 0.8mm, synchronous correction is triggered: that is, the command to be sent to the hydraulic actuator other than the hydraulic actuator corresponding to the deviation exceeds the standard is suspended until the deviation is restored to within 0.5mm and then synchronous adjustment is resumed.

[0043] In this embodiment, the area-Mach number interpolation curve is specifically as follows: ; in, It is a power exponent, and its value range is... When m < 1, the area adjustment is faster in the early stage (low speed stage) and slower in the later stage (high speed stage). The area adjustment is slower in the initial stage and faster in the later stage; in specific applications... The specific values ​​are determined through ground-based direct-connection tests based on the area-Mach number interpolation curve, so as to ensure the outlet pressure of the first flow channel at different flight Mach numbers. static pressure with environment The ratio satisfies .

[0044] In this embodiment, when the aircraft's flight Mach number exceeds a preset lower threshold (e.g.) (When), and the actual outlet area of ​​the adjustable flow channel exceeds the preset transition threshold. At that time, the FADEC control unit initiates the second thrust unit shutdown transition procedure, in which... .

[0045] In the specific implementation process, the shutdown transition procedure for the second thrust unit includes: The outlet area of ​​the adjustable flow channel is gradually increased, while the propellant supply flow rate of the second thrust unit is gradually reduced according to the attenuation curve. After the adjustable flow channel reaches the expansion state, a preset time delay (e.g., 0.5s~2.0s) is maintained before the propellant supply of the second thrust unit is shut off, completing the mode switch. The attenuation curve is specifically as follows: ; in, , The thrust of the second thrust unit before and after attenuation. It is the decay exponent, and .

[0046] It is worth noting that during the monotonically increasing process of the adjustable flow channel outlet area, the increment of the outlet area is a continuous value, and the gradient of the area change does not exceed [a certain value]. 5% per 0.1 Ma. In addition, during mode switching, if the thrust decay rate of the second thrust unit exceeds the preset safety threshold, the thrust descent rate will be automatically limited to prevent the aircraft from experiencing attitude disturbances due to sudden thrust changes; when the hydraulic system pressure is detected to be lower than the safety threshold of 12 MPa, the fault protection mode is triggered, the adjustable flow channel is automatically locked at the current position, the second thrust unit maintains the current thrust level unchanged, and reports the fault status to the flight control system.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A parallel adjustable nozzle for a combined power system, characterized in that, Includes an outer casing, a first flow channel, a second flow channel, and an adjustable flow channel; The first flow channel is coaxially disposed inside the outer shell, and the second flow channel is located between the outer shell and the first flow channel, with each of the second flow channels spaced circumferentially around the first flow channel; The outlet of the second flow channel is located downstream of the outlet of the first flow channel. The adjustable flow channel includes a plurality of fish scale adjustment plates arranged circumferentially, and the first end of each fish scale adjustment plate is hinged to the outlet edge of the first flow channel. The adjustable flow channel has a contraction state and an expansion state: In the contracted state, the leading edge of each of the fish scale adjustment plates converges toward the axis of the first flow channel, and the outer contour of the fish scale adjustment plate is located radially inside the outlet section of the second flow channel, that is, the second flow channel is completely exposed. In the expanded state, the leading edge of each of the fish scale adjustment plates opens away from the axis of the first flow channel, and the tail end of each fish scale adjustment plate extends to the inner wall of the outer shell, blocking the second flow channel. The number of fish scale adjustment plates satisfy ,and The number is even; the axial projection length of each of the fish scale adjustment plates is... The diameter of the tail end of the outer shell The ratio satisfies Furthermore, the axial distance between the hinge axis of the fish scale adjusting plate and the outlet section of the first flow channel is not greater than [missing information]. The inner wall surface of each of the fish scale adjustment plates forms a continuously adjustable axisymmetric gradually expanding surface between the contracted and expanded states, and the circumferential overlap width between two adjacent fish scale adjustment plates in the expanded state is not less than 5% of the circumferential width of the fish scale adjustment plate; Number of second flow channels satisfy The M second flow channels are evenly distributed along the circumference at equal angular intervals of 360° / M; the outlet cross-sectional diameter of the second flow channel is... The radial distance between the center of the outlet section of the second flow channel and the axis of the first flow channel is... ,satisfy: , , The axial distance between the axial position of the second flow channel outlet section and the axial position of the first flow channel outlet section. satisfy .

2. The parallel adjustable nozzle for a combined power system according to claim 1, characterized in that, The outlet cross-sectional area of ​​the adjustable flow channel in the contracted state is: The outlet cross-sectional area of ​​the adjustable flow channel in the expanded state is ,and ; The minimum outlet diameter of the adjustable flow channel in the contracted state satisfy ,in The outlet diameter of the first flow channel.

3. The parallel adjustable nozzle for a combined power system according to claim 1 or 2, characterized in that, A high-temperature flexible sealing structure is provided on the overlapping surface between two adjacent fish scale adjustment plates, and the high-temperature flexible sealing structure adopts an overlapping labyrinth seal. In the expanded state, a metal O-ring is provided between the tail end of the adjustable flow channel and the inner wall of the outer casing.

4. The parallel adjustable nozzle for a combined power system according to claim 1 or 2, characterized in that, It also includes a drive device, which comprises a plurality of hydraulic actuators evenly arranged circumferentially; Each of the hydraulic actuators achieves the synchronous extension and retraction of all the fish scale adjustment plates through a mechanical synchronous linkage mechanism or an electro-hydraulic servo synchronous circuit.

5. The parallel adjustable nozzle for a combined power system according to claim 1 or 2, characterized in that, An annular heat-insulating baffle is provided between the first flow channel and each of the second flow channels. The annular heat-insulating baffle has a multi-layer structure, including an inner thermal barrier coating, a middle aerogel heat-insulating felt or vacuum interlayer, and an outer heat-resistant alloy support shell.

6. A control method applied to a parallel adjustable nozzle for a combined power system as described in any one of claims 1 to 5, characterized in that, The parallel adjustable nozzle is installed on the aircraft. The combined power system on the aircraft includes a first thrust unit and several second thrust units that correspond one-to-one with the second flow channels. The thrust outlet of the first thrust unit is connected to the inlet of the first flow channel, and the thrust outlet of the second thrust unit is connected to the inlet of the corresponding second flow channel. The control method includes the following steps: Step 1: Obtain the current Mach number of the aircraft. ; Step 2: Based on the current flight Mach number Calculate the target outlet area of ​​the adjustable flow channel according to the preset control law. ; Step 3: Based on the target outlet area of ​​the adjustable flow channel Compared with actual export area The error between them generates a drive control signal, which adjusts the radial position of the fish scale adjustment plate to change the outlet area.

7. The control method according to claim 6, characterized in that, The target export area The calculation process is as follows: when At that time, the target export area or ,in, The lowest Mach number at which the first thrust unit can operate independently. The outlet cross-sectional area of ​​the adjustable flow channel in the contracted state; when At that time, the target exit area is calculated based on the area-Mach number interpolation curve. : in, This refers to the outlet cross-sectional area of ​​the adjustable flow channel in the expansion state. It is a power exponent; when At that time, the target export area or ,in, This is the design point Mach number for the first thrust unit.

8. The control method according to claim 7, characterized in that, When the aircraft's flight Mach number exceeds a preset lower threshold and the actual outlet area of ​​the adjustable flow channel exceeds a preset transition threshold, the second thrust unit shutdown transition procedure is initiated, including: Gradually increase the outlet area of ​​the adjustable flow channel, and at the same time gradually reduce the propellant supply flow rate of the second thrust unit according to the attenuation curve. After the adjustable flow channel reaches the expansion state, delay for a preset time, and then shut off the propellant supply of the second thrust unit to complete the mode switch. The attenuation curve is specifically as follows: in, , The thrust of the second thrust unit before and after attenuation. This is the decay index.

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