Gas compressor last-stage blade tip clearance dynamic regulation and control device and method based on phase change materials and application of gas compressor last-stage blade tip clearance dynamic regulation and control device and method

Abstract

The invention provides a dynamic regulation and control device and method for a last-stage blade tip clearance of a gas compressor based on a phase-change material and application. Firstly, based on the dynamic change rule of the blade top clearance of the gas compressor under different cold and hot state working conditions, the regulation and control requirements of the last-stage blade top clearance are determined; according to the thermophysical and structural deformation characteristics of the phase change material, a correlation model of different temperature excitation and the deformation scale of the phase change material is constructed. The dynamic blade tip clearance regulating and controlling device based on the phase-change material comprises a displacement control rod, a reset spring, a piston, a piston sealing ring, the phase-change material and an outer shell. When the temperature rises to a critical point or above, thermal excitation causes volume expansion of the phase change material, the piston and the displacement control rod are pushed to move outwards in the radial direction, and the gap is increased; when the temperature is reduced, the phase change material shrinks, the reset spring pushes the piston to return to the original position, and the gap is reduced. And fine regulation and control of the blade tip clearance are realized by screening temperature excitation and phase change material key parameters required by different working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of aero-engine compression systems, relates to the technology of dynamic regulation of compressor tip clearance, and specifically relates to a device, method and application for realizing dynamic regulation of the tip clearance of the last stage of a compact compressor through phase change materials, which are used to accurately control the tip clearance of a compact compressor under different working conditions and solve the problems of efficiency decline and instability caused by dynamic changes in the tip clearance. Background Art

[0002] In order to further expand the flight airspace, modern high-performance turbofan engines have put forward more stringent requirements for fuel economy. The bypass ratio of turbofan engines gradually increases, the structure of the core engine becomes more compact, the size of the axial compressor blades equipped is significantly reduced, and the height of the last stage blades is only 5-10 mm. However, due to the limitations of processing, assembly, and the conversion between cold and hot working conditions, the compressor tip clearance cannot be reduced synchronously, resulting in the increase of the tip clearance at the top of the last stage blades to more than 4% of the relative blade height, forming a so-called "open" clearance. Compared with the conventional clearance (below 3% of the blade height), double leakage occurs at the tip under the open clearance. When the double leakage phenomenon occurs, the vortex-vortex interference causes the leakage vortices in adjacent blade channels to break, which not only accelerates the generation of local turbulent pulsation and reduces the efficiency, but also easily triggers instability and threatens flight safety. Therefore, how to efficiently control the tip clearance of the last stage of a compact compression system has become one of the key factors to ensure the stable operation of turbofan engines.

[0003] Tip clearance control essentially adjusts the deformation response of the disk / casing, the stress response of the rotor blades, or both. Under different working conditions, the thermal expansion amplitude of the disk / casing and the centrifugal force of the rotor show great differences, and the tip clearance shows highly dynamic change characteristics. For the last stage blades, high temperature and high stress lead to more significant amplitude fluctuations in the tip clearance scale, bringing greater challenges to the fine regulation of the clearance.

[0004] Common clearance regulation strategies can be divided into active regulation and passive regulation. According to different regulation principles, they can be further divided into passive / active thermal regulation, active / passive pneumatic regulation, mechanical regulation, etc. Among them, passive thermal regulation mainly adjusts the tip clearance between the rotor and stator according to the operating temperature of the components and the thermophysical properties of the materials. For example, introducing high-temperature gas from the rear high-pressure stage to heat the casing and shrink the clearance; or introducing cooling gas from the front stage to cool the casing and expand the clearance. Compared with active regulation, passive thermal regulation can achieve clearance regulation on the premise of minimizing structural complexity as much as possible, and is the preferred strategy for current tip clearance regulation. Although passive thermal regulation has the advantage of simple structure, it is usually difficult to accurately estimate the deformation size of the disk / casing under heating conditions in advance, and the control accuracy of the tip clearance is limited.

[0005] In summary, it is difficult for the existing technologies to balance the multiple requirements of the compact compressor tip clearance regulation for dynamic response speed, control accuracy, and structural reliability. Especially under the high-temperature and high-stress conditions at the last stage, the efficiency decline and instability risk caused by the open clearance are particularly prominent. Therefore, it is urgent to explore a tip clearance regulation technology with higher precision and good response performance to meet the requirements of the high-performance turbofan engine for the fine regulation of the tip clearance of the last-stage compressor blades. Summary of the Invention

[0006] (1) Objectives of the Invention When the temperature of a phase change material (such as alkane organic polymers) exceeds the critical point, a phase change process occurs. This process not only absorbs and releases a large amount of thermal energy, but also undergoes a significant change in volume. Based on the thermophysical properties and structural deformation characteristics of the phase change material, the present invention proposes a dynamic regulation device, method, and application for the tip clearance of the last stage of a compact compressor. By strictly deriving the correlation model between different temperature excitations and the deformation scale of the phase change material, a quantitative relationship between the clearance change, external temperature excitation, and key parameters of the phase change material is established. A dynamic regulation device for the tip clearance based on the phase change material is designed to achieve the fine control of the tip clearance of the last-stage compressor blades, providing support for ensuring the stable operation of the compact compression system.

[0007] (2) Technical Solutions To achieve the objectives of the invention and solve its technical problems, the present invention adopts the following technical solutions: The first objective of the present invention is to provide a dynamic regulation device for the tip clearance of the last stage of a compressor based on a phase change material, which at least includes: A flexible casing, facing the tip clearance of the last stage of the compressor, with its axial starting and ending positions located outside the leading edge and trailing edge of the last-stage blade tip respectively, for undergoing radial local deformation under the traction of an external regulation force to dynamically adjust the size of the tip clearance; An external housing, fixedly arranged outside the flexible casing, with its interior forming a sealed space, and an external excitation heat source provided on its outer wall for providing an external excitation temperature to the regulation assembly; A piston, arranged inside the external housing, dividing the internal space of the housing into a lower space and an upper space adjacent to and away from the flexible casing respectively, and capable of linear movement; A phase change material, hermetically filled in the lower space of the housing, having a reversible temperature response characteristic, with its phase change critical point temperature matching the operating conditions of the compressor, and expanding or contracting in volume according to the excitation temperature of the external heat source to push the piston up or down; A return spring, arranged in the upper space of the housing, for applying a pre-tightening force to the piston, pushing the piston to reset when the phase change material contracts, and its stiffness coefficient and initial compression amount are set according to the regulation range of the tip clearance; A displacement control rod, with one end connected to the piston and the other end passing through the outer housing and connected to the flexible casing, is used to transfer the radial linear displacement of the piston to the flexible casing, driving it to generate local structural deformation and realizing the dynamic adjustment of the tip clearance of the last stage of the compressor.

[0008] The second object of the present invention is to provide a compressor, including the above-mentioned dynamic regulation device for the tip clearance of the last stage based on phase change materials.

[0009] The third object of the present invention is to propose a dynamic regulation method for the tip clearance of the last stage of a compact compressor. Based on the above-mentioned dynamic regulation device for the tip clearance of the last stage of the compressor based on phase change materials, the precise control of the tip clearance is realized by using the thermal excitation deformation of the phase change material. The key of this method lies in establishing the correlation model between the temperature excitation and the deformation scale of the phase change material and the design of the dynamic regulation device for the tip clearance based on the phase change material. The main implementation steps of this method are as follows: SS1. Determine the regulation requirements for the tip clearance of the last stage of the compressor: With the help of numerical simulation or experimental measurement, obtain the dynamic response law of the tip clearance of the last stage of the compact compressor under different cold and hot conditions, and clarify the regulation requirements for the tip clearance of the last stage, including the dynamic regulation target values for increasing or decreasing the tip clearance of the last stage; SS2. Establish the correlation model between the temperature excitation and the change of the tip clearance: Based on the thermophysical properties and structural deformation characteristics of the phase change material, establish the radial change amount Δ L of the tip clearance of the last stage of the compressor and the external temperature excitation intensity Δ T The linear correlation model between them quantifies the corresponding relationship between the change of the tip clearance and the external temperature excitation and the key parameters of the phase change material: Among them, d is the inner diameter of the housing, k is the spring stiffness coefficient, L 0 is the initial volume of the phase change material in the outer housing V 0 corresponding initial length, F f is the resultant force of the piston-wall friction force and the tip aerodynamic force; SS3. Configure the structure and control parameters of the tip clearance dynamic regulation device: Combined with the thermal-mechanical-aerodynamic boundary conditions of the target compressor under different conditions and the tip clearance regulation requirements of the last stage, select the phase change material that meets the requirements of the critical phase change temperature, expansion rate and shrinkage rate, and determine the external housing size, the spring stiffness coefficient k of the return spring, the initial compression amount and the initial filling volume V0, and verify the regulation effect through experiments and / or numerical simulations to ensure that the radial change Δ of the tip clearance L is within the desired range and is linearly positively correlated with the external temperature excitation intensity Δ T to achieve rapid response and high-precision control during the regulation process; SS4. Implement dynamic regulation of the tip clearance: Install the regulation device at the last stage of the compact compressor, monitor the temperature field change and clearance change at the tip of the last stage in real time, and control the external temperature excitation intensity in real time to achieve real-time matching of the dynamic adjustment of the tip clearance at the last stage and the operating conditions.

[0010] (III) Technical effects Compared with the prior art, the dynamic regulation device, method and application of the tip clearance at the last stage of the compact compressor of the present invention have the following beneficial and remarkable technical effects: (1) Simple structure and easy to implement. Aiming at the problem that there are significant differences in the deformation responses of the disk / casing and the stress responses of the rotor blades under different operating conditions, which lead to highly dynamic changes in the tip clearance, the present invention proposes an idea of using the thermophysical properties and structural deformation of phase change materials to control the tip clearance. The regulation device of the present invention only needs to arrange core components such as phase change materials, pistons, return springs and displacement control rods, without complex driving devices or control systems. Compared with active / passive pneumatic regulation and mechanical regulation, etc., this scheme greatly reduces the structural complexity of the clearance regulation device.

[0011] (2) High regulation accuracy, easy to adjust and control. Starting from the thermophysical properties and structural deformation characteristics of phase change materials, the present invention strictly derives the correlation model between different temperature excitations and the deformation scale of phase change materials, and quantifies the corresponding relationship between the dynamic change of the tip clearance and the key parameters of the regulation mechanism. Based on the above-mentioned tip clearance dynamic regulation device with phase change materials as the core, by optimizing the critical temperature, expansion rate, shrinkage rate of the phase change materials and the structural parameters of the regulation mechanism, fine control of the tip clearance under different operating conditions is achieved, providing a fundamental support for the stable and efficient operation of the last-stage compressor.

[0012] (3) The present invention has high adaptability and reliability and can be widely applied to different models of compact compressors. The key parameters of the phase change materials and the regulation mechanism can be optimized and adjusted according to specific application scenarios to ensure its stable operation under different temperature, pressure and speed conditions. In addition, the reversible phase change characteristics of the phase change materials make it have high durability and reliability during long-term use, and can meet the requirements of aeroengines for high reliability and long life. Description of the drawings

[0013] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. Hereinafter, the embodiments of the present invention will be described in detail in conjunction with the accompanying drawings, wherein: Figure 1 It is a schematic diagram of the dynamic regulation device for the tip clearance of the last stage of the compressor based on phase change material of the present invention; Figure 2 It is a schematic diagram of the force analysis during the phase change process of the phase change material in the present invention; Figure 3 It is a corresponding relationship diagram between the radial change amount of the tip clearance and the excitation temperature under different regulation conditions; Figure 4 It is a flow chart of the dynamic regulation method for the tip clearance of the last stage of the compact compressor of the present invention.

[0014] Explanation of reference numerals: 1 - External housing, 2 - Piston, 3 - Phase change material, 4 - Return spring, 5 - Displacement control rod, 6 - Piston seal ring, 7 - Flexible casing, 100 - Rotor blade, 101 - Rotor tip clearance, 102 - Stator blade, 103 - Stator clearance, 104 - Casing, 105 - Hub. Detailed implementation manners

[0015] The present invention aims to propose a dynamic regulation device, method and application for the tip clearance of the last stage of a compact compressor. To make the purpose, technical solution and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, not all of the embodiments, and the described embodiments are exemplary and are intended to explain the present invention and should not be construed as a limitation of the present invention.

[0016] Embodiment 1: Dynamic regulation device for tip clearance As a specific embodiment, Figure 1 A schematic diagram of the dynamic regulation device for the tip clearance of the last stage of the compressor based on phase change material of the present invention is given. As the pressure ratio and the air flow density increase along the flow direction, the compressor flow passage gradually narrows, and the heights of the rotor blade 100 and the stator blade 102 decrease. A radial stator clearance 103 is formed between the root of the stator blade 102 and the hub 105, and a radial rotor tip clearance 101 is formed between the rotor tip and the casing 104. The low-energy fluid near the end wall flows from the pressure surface through the clearance into the adjacent blade passage, forming a clearance leakage flow, which has a significant impact on the efficiency and stability of the last stage of the compressor.

[0017] Taking the regulation of the rotor tip clearance as an example, the dynamic regulation device for the tip clearance of the last stage compressor of the present invention includes a flexible casing 7, a displacement control rod 5, a return spring 4, a piston 2, a piston seal ring 6, a phase change material 3, an external casing 1, etc. Among them, the phase change material 3 plays a major role in the clearance control. In the present invention, the phase change material 3 can be selected from alkane organic polymers, and the phase change process is accompanied by a large amount of heat absorption and release. In addition, the alkane phase change material also has the advantages of low cost and easy preparation. When the external heat source excitation temperature exceeds the phase change critical point, the volume of the phase change material 4 inside the cylindrical external casing 1 expands, pushing the piston 2 to compress the return spring 4 and driving the displacement control rod 5 to move upward. At this time, the flexible casing 7 is recessed upward under the traction of the displacement control rod 5, and the rotor tip clearance 101 increases. When the external heat source excitation temperature is lower than the phase change critical point, the material volume shrinks. Under the action of the return spring 4, the displacement control rod 5 pushes the piston 2 to move downward, the flexible casing 7 bulges downward, and the rotor tip clearance 101 decreases. Therefore, the change of the rotor tip clearance 101 (corresponding to the control accuracy of the regulation device) directly depends on the external temperature excitation and the key parameters of the phase change material.

[0018] Specifically, as Figure 1 shown, in the dynamic regulation device for the tip clearance of the last stage compressor of the present invention, the flexible casing 7 is arranged opposite to the rotor tip clearance 101 of the last stage compressor. Its axial starting and ending positions are respectively located outside the leading edge and trailing edge of the tip of the last stage blade, and it is used to generate radial local deformation under the traction of the external regulation force to dynamically adjust the size of the tip clearance 101. The external casing 1 is fixedly arranged outside the flexible casing 7, and its interior forms a closed space. The outer wall is provided with an external excitation heat source for providing an external excitation temperature to the regulation component. The piston 2 is radially movably arranged inside the external casing 1 and divides the internal space of the casing 1 into a lower space and an upper space adjacent to and away from the flexible casing 7. The phase change material 3 is hermetically filled in the lower space of the casing 1 and has a reversible temperature response characteristic. Its phase change critical point temperature matches the operating conditions of the compressor, and it expands or contracts in volume according to the excitation temperature of the external heat source to push the piston 2 to move upward or downward. The return spring 4 is arranged in the upper space of the casing 1 and is used to apply a pre-tightening force to the piston 2. When the phase change material 3 shrinks, it pushes the piston 2 to reset. Its stiffness coefficient and initial compression amount are set according to the regulation range of the tip clearance 101. One end of the displacement control rod 5 is connected to the piston 2, and the other end passes through the external casing 1 and is connected to the flexible casing 7, and is used to transfer the radial linear displacement of the piston 2 to the flexible casing 7 to drive the local structure thereof to deform and realize the dynamic regulation of the tip clearance 101 of the last stage compressor.

[0019] The dynamic regulation device for the tip clearance of the last stage of the compressor of the present invention focuses on establishing a correlation model between different temperature excitations and the deformation scale of the phase change material. By quantifying the correspondence among the temperature excitation, the key parameters of the phase change material, and the change in the tip clearance, fine control of the tip clearance of the last stage of the compact compressor is achieved. For the phase change material, when the temperature is higher / lower than the critical point, volume expansion / contraction occurs during the phase change process. The volume expansion rate α and the shrinkage rate β are respectively defined as follows: (1) In the above formula, V, P, T respectively represent the volume, pressure, and temperature of the phase change material inside the cylindrical shell. When the phase change process occurs, the following relationship is satisfied: (2) The initial and end states of the phase change process are respectively marked as "0" and "1", and then by integration, we can obtain: (3) That is: (4) Among them: are respectively the change amounts of the material volume, pressure, and temperature before and after the phase change, V 0 is the initial volume of the phase change material filled inside the cylindrical shell.

[0020] During the entire phase change process, when the volume change d of the phase change material inside the cylindrical shell (with a diameter of ), the return spring is compressed , and the following relationship exists: (5) Perform a force analysis on the control volumes of the return spring 4 and the phase change material 3, as shown below Figure 2 ( F f is the resultant force of the friction between the piston 2 and the wall surface, the tip aerodynamic force, etc.) It can be seen that: (6) Combining (4), (5), and (6), it can be known that: (7) It can be seen from formula (7) that the radial change amount Δ L of the tip clearance and the external temperature excitation intensity ΔT maintain a strict linear relationship. Based on the parameters of the tip clearance dynamic regulation device of the phase change material 3 ( α , β , d , L 0 andk etc.), the dynamic change Δ of the tip clearance can be clearly determined L The required temperature excitation intensity ΔT so as to achieve rapid and precise control of the tip clearance.

[0021] Taking a certain set of regulation parameters as an example, Figure 3 The radial change Δ of the tip clearance under different regulation conditions was compared L with the corresponding relationship of temperature. The critical temperature of the phase change material is 40 °C. When the external temperature exceeds this value, the phase change process causes the material to deform and the tip clearance to change. Within the phase change interval, the dynamic change Δ of the tip clearance L is linearly and positively correlated with the temperature excitation intensity Δ T Moreover, the diameter of the outer shell of the regulation device d has a significant impact on the change of the tip clearance, d the larger the value, the more obvious its regulation effect.

[0022] Preferably, the phase change material 3 is selected as an alkane-based organic polymer material with thermophysical stability and reversible volume deformation ability, and its phase change critical point temperature T c , volume expansion rate α and shrinkage rate β are modulated and set to match the temperature change range under different operating states of the compressor to ensure that the dynamic regulation of the tip clearance can achieve rapid response and high-precision adjustment under different flight conditions. The stiffness coefficient k and initial compression amount of the return spring 4 are matched and set according to the volume expansion characteristics of the phase change material, the friction between the piston and the wall surface, and the required tip clearance regulation range. The inner diameter d of the outer shell 1 is designed in combination with the piston displacement Δ L , the volume change amount Δ of the phase change material V and the flexible casing regulation sensitivity are comprehensively determined to maximize the volume utilization efficiency of the regulation structure.

[0023] Preferably, the external excitation heat source is a temperature-controllable electric heating device or a thermal fluid circulation system, and is connected to the feedback control system through a gap sensor and a temperature sensor arranged in the area near the inner wall of the flexible casing 7, and the change of the tip clearance and the temperature field change in the last stage area of the compressor are monitored in real time and the excitation temperature is adjusted in real time to achieve closed-loop feedback control of the excitation temperature of the phase change material and ensure the real-time matching of the dynamic adjustment of the tip clearance and the operating conditions of the compressor.

[0024] Preferably, a piston seal ring 6 is provided between the piston 2 and the wall surface of the external housing 1, which is preferably made of a corrugated flexible structure or a graphite-reinforced composite material to prevent the phase change material 3 from leaking into the upper space of the housing 1, and at the same time reduce the frictional resistance and lateral disturbance during the movement of the piston 2; a sliding guiding mechanism and a sealing structure are preferably provided at the penetration of the displacement control rod 5 and the external housing 1 to ensure that the movement direction of the displacement control rod is consistent with the radial displacement direction of the piston and prevent the phase change material from leaking to the outside of the housing.

[0025] Embodiment 2: Dynamic regulation method Based on the dynamic regulation device for the tip clearance of the last stage of the compressor based on the phase change material shown in the above Embodiment 1, this Embodiment 2 focuses on introducing the dynamic regulation method for the tip clearance of the last stage of the compact compressor based on this regulation device. This method realizes the rapid and precise control of the tip clearance by establishing a correlation model between the temperature excitation and the deformation scale of the phase change material, and quantifying the corresponding relationship between the tip clearance change, the external temperature excitation and the key parameters of the phase change material. The specific regulation method includes the following steps: SS1. Determine the regulation requirements for the tip clearance of the last stage of the compressor: With the help of numerical simulation or experimental measurement, obtain the dynamic response law of the tip clearance of the last stage of the compact compressor under different cold and hot conditions, and clarify the regulation requirements for the tip clearance of the last stage, including the dynamic regulation target values for increasing or decreasing the tip clearance of the last stage. Specifically, the thermal-mechanical response data of the casing and the compressor rotor under typical conditions such as startup, acceleration, cruise, and deceleration should be combined to analyze the thermal expansion amplitude of the disk / casing, the change of the rotor centrifugal force, the dynamic change trajectory of the tip clearance, the maximum fluctuation amplitude and its influence on the aerodynamic performance, etc., so as to determine the response interval and regulation accuracy range required by the regulation mechanism, and provide boundary conditions and design basis for the subsequent device parameter configuration and model establishment.

[0026] SS2. Establish a correlation model between the temperature excitation and the tip clearance change: Based on the thermophysical properties and structural deformation characteristics of the phase change material, establish a linear correlation model between the radial change amount Δ L of the tip clearance of the last stage of the compressor and the external temperature excitation intensity Δ T to quantify the corresponding relationship between the tip clearance change, the external temperature excitation and the key parameters of the phase change material: Among them, d is the inner diameter of the housing, k is the spring stiffness coefficient, L 0 is the initial volume of the phase change material in the external housing V 0 is the initial length, F f is the resultant force of the frictional force between the piston and the wall surface and the aerodynamic force at the tip.

[0027] Through this model, the maximum gap adjustment amount that the regulation device can provide under different temperature excitation conditions can be predicted, providing a theoretical basis for the parameter optimization of the regulation device and the formulation of the closed-loop control strategy.

[0028] SS3. Configure the structure and control parameters of the tip clearance dynamic regulation device: Combined with the thermal-fluid-aerodynamic boundary conditions of the target compressor under different operating conditions and the tip clearance regulation requirements of the last stage, select phase change materials that meet the critical phase change temperature requirements, have a high volume expansion rate, and a fast reaction rate, and determine the external shell size, the stiffness coefficient of the return spring k and the initial compression amount, as well as the initial filling volume of the phase change material V 0, and verify the regulation effect through experiments and / or numerical simulations to ensure that the radial change amount Δ of the tip clearance L is within the expected range and shows a linear positive correlation with the external temperature excitation intensity Δ T to achieve fast response and high-precision control during the regulation process. For example, select alkane organic polymers with a phase change critical temperature of 40°C to 80°C to ensure that they can quickly respond to temperature changes under typical operating conditions of the compressor; at the same time, optimize the stiffness coefficient of the return spring k to ensure that it can quickly push the piston back to its original position when the phase change material shrinks, achieving precise adjustment of the gap. In addition, according to the structural integration space, aerodynamic disturbance tolerance, and heat load limitation, optimize the installation position and arrangement method of the regulation device on the casing to ensure the stability of the dynamic response and the safety margin of the local structural strength.

[0029] SS4. Implement the dynamic regulation of the tip clearance: Install the regulation device at the last stage of the compact compressor, monitor the gap change at the tip of the last stage and the temperature field change in the last stage region of the compressor in real time, and control the external temperature excitation intensity in real time to achieve dynamic adjustment of the tip clearance and real-time matching with the operating conditions of the compressor. Specifically, the system can dynamically adjust the output power of the heat source based on the data collected by the gap sensor and the temperature sensor, using the preset feedback control logic to keep the phase change material always in the high-response interval, ensuring that the regulation rate meets the requirements of short-time variable operating conditions during flight, and further improving the aerodynamic stability and energy efficiency index of the last-stage compressor. For example, when the temperature rises above the critical point, the thermal excitation causes the phase change material to expand in volume, pushing the piston and the displacement control rod to move radially outward, increasing the gap; when the excitation temperature decreases, the phase change material shrinks, and the return spring pushes the piston back to its original position, reducing the gap.

[0030] Through the above steps, the dynamic regulation method for the tip clearance of the last stage of the compressor of the present invention realizes the rapid and precise adjustment of the tip clearance by establishing a correlation model between the temperature excitation and the deformation scale of the phase change material, optimizing the structure and control parameters of the regulation device, and implementing closed-loop control. This method can effectively cope with the dynamic changes of the clearance under different working conditions, reduce the double leakage phenomenon at the tip, improve the efficiency and stability of the compressor, and provide reliable technical support for the compact compression system of high-performance turbofan engines.

[0031] Through the above embodiments, the object of the present invention is completely and effectively achieved. Those skilled in the art can understand that the present invention includes but is not limited to the content described in the drawings and the above specific embodiments. Although the present invention has been described with reference to the currently considered most practical and preferred embodiments, it should be understood that the present invention is not limited to the disclosed embodiments, and any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A dynamic regulation device for the tip clearance of the last stage of a compressor based on phase change materials, characterized in that, Comprising: A flexible casing, which is arranged opposite to the tip clearance of the last stage of the compressor, and its axial starting and ending positions are respectively located outside the leading edge and trailing edge of the tip of the last stage blade; An outer casing, which is fixedly arranged outside the flexible casing, and the interior thereof forms a sealed space, and the outer wall is provided with an external excitation heat source; A piston, which is arranged inside the outer casing, divides the internal space of the casing into a lower space and an upper space adjacent to and away from the flexible casing, and can move linearly; A phase change material, which is hermetically filled in the lower space of the casing, has a reversible temperature response characteristic, and its phase change critical point temperature matches the operating conditions of the compressor, and expands or contracts in volume under the excitation of the external heat source to push the piston to move upward or downward; A return spring, which is arranged in the upper space of the casing, is used to apply a pre-tightening force to the piston, and pushes the piston to reset when the phase change material contracts, and its stiffness coefficient and initial compression amount are set according to the regulation range of the tip clearance; A displacement control rod, one end of which is connected to the piston, and the other end passes through the outer casing and is connected to the flexible casing, and is used to transfer the linear displacement of the piston to the flexible casing, drive it to generate local structural deformation, and realize the dynamic adjustment of the tip clearance of the last stage of the compressor.

2. The compressor last-stage tip clearance dynamic regulation device based on phase change material according to claim 1, characterized in that: The phase change material is selected as an alkane organic polymer material with thermophysical stability and reversible volume deformation ability, and its phase change critical point temperature T c , volume expansion rate α and shrinkage rate β are modulated and set to match the temperature change range under different operating states of the compressor.

3. The compressor last-stage tip clearance dynamic regulation device based on phase change material according to claim 2, wherein: During the phase change process of the phase change material, its volume change Δ V and the temperature change Δ T , the pressure change Δ p satisfy . The temperature change Δ T of the phase change material is consistent with the external temperature excitation intensity, where α , β , V 0 are the volume expansion rate, shrinkage rate and initial volume of the phase change material respectively, and , V , p , T are the volume, pressure and temperature of the phase change material respectively.

4. The compressor last-stage tip clearance dynamic regulation device based on phase change material according to claim 3, characterized in that: The external housing is of a cylindrical structure, and the inner diameter of the housing d is comprehensively determined by combining the piston displacement Δ L , the volume change Δ V of the phase change material, and the regulation sensitivity of the flexible casing, and satisfies the relational expression , where the piston displacement Δ L is consistent with the compression amount of the return spring, the displacement amount of the displacement control rod, and the change amount of the tip clearance.

5. The compressor last-stage tip clearance dynamic regulation device based on phase change material according to claim 4, characterized in that: The stiffness coefficient of the reset spring k and the initial compression amount are matched and set according to the volume expansion characteristics of the phase change material, the friction force between the piston and the wall surface, and the required regulation range of the tip clearance, so as to satisfy the force balance relationship , where Δ p is the pressure change during the phase change of the phase change material, F f is the resultant force of the friction force between the piston and the wall surface and the tip aerodynamic force.

6. The compressor last-stage tip clearance dynamic regulation device based on a phase change material according to claim 5, wherein: The change amount Δ of the tip clearance L and the external temperature excitation intensity Δ T satisfy a linear relationship , where k is the stiffness coefficient of the return spring, L 0 is the initial volume of the phase change material in the outer housing V and the corresponding initial length. By selecting and setting the phase change material parameters α , β , V 0, the inner diameter of the housing d and the spring stiffness coefficient k , the dynamic control response speed and sensitivity of the tip clearance are adjusted to meet the clearance regulation requirements under different working conditions.

7. The compressor last-stage tip clearance dynamic regulation device based on phase change material according to claim 1, characterized in that: The external excitation heat source is a temperature-controllable electric heating device or a hot fluid circulation system, and is communicatively connected with a feedback control system through a clearance sensor and a temperature sensor arranged near the inner wall of the flexible casing, and the changes of the tip clearance and the temperature field in the last stage area of the compressor are monitored in real time and the excitation temperature is adjusted in real time, so as to realize the closed-loop feedback control of the excitation temperature of the phase change material and ensure the real-time matching of the dynamic adjustment of the tip clearance and the operating conditions of the compressor.

8. The compressor last-stage tip clearance dynamic regulation device based on phase change material according to claim 1, wherein: A piston seal ring is arranged between the piston and the wall surface of the outer casing, which is made of a corrugated flexible structure or a graphite-reinforced composite material, so as to prevent the phase change material from leaking into the upper space of the casing, and at the same time reduce the frictional resistance and lateral disturbance during the movement of the piston; a sliding guiding mechanism and a sealing structure are arranged at the penetration of the displacement control rod and the outer casing, so as to ensure that the movement direction of the displacement control rod is consistent with the radial displacement direction of the piston, and prevent the phase change material from leaking to the outside of the casing.

9. A compressor, characterized in that, Comprising the dynamic regulation device for the tip clearance of the last stage of the compressor based on the phase change material according to any one of the above claims 1 to 8.

10. A dynamic regulation method for the tip clearance of the last stage of a compressor, based on the dynamic regulation device for the tip clearance of the last stage of a compressor based on phase change material according to any one of the above claims 1 to 8, characterized in that, Comprising: SS1. By means of numerical simulation or experimental measurement, obtain the dynamic response law of the tip clearance of the last stage under different cold and hot state conditions, and clarify the regulation requirements of the tip clearance of the last stage; SS2. Based on the thermophysical properties and structural deformation characteristics of the phase change material, establish a linear correlation model between the radial change Δ L of the tip clearance at the last stage of the compressor and the external temperature excitation intensity Δ T : Among them, d is the inner diameter of the housing, k is the spring stiffness coefficient, L 0 is the initial volume of the phase change material in the outer housing V and the corresponding initial length, F f is the resultant force of the piston-wall friction and the tip aerodynamic force, α and β are the volume expansion rate and the volume shrinkage rate of the phase change material, respectively; SS3. Combine the thermal - mechanical - aerodynamic boundary conditions of the target compressor under different operating conditions and the requirements for regulating the tip clearance of the last stage, select the phase - change material that meets the requirements of the critical phase - change temperature, expansion rate, and contraction rate, and determine the external shell size, the stiffness coefficient of the return spring k , the initial compression amount, and the initial filling volume of the phase - change material V 0, and verify the regulation effect through experiments and / or numerical simulations to ensure that the change amount of the tip clearance Δ L is within the expected range and shows a linear positive correlation with the external temperature excitation intensity Δ T ; SS4. Install the regulation device at the last stage of the compact compressor, monitor the temperature field change and clearance change of the tip of the last stage in real time, and control the external temperature excitation intensity in real time, so as to realize the real-time matching of the dynamic adjustment of the tip clearance of the last stage and the operating conditions.

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