Pneumatic cooling parameter optimization method for magnetic suspension natural gas differential pressure generator

Abstract

The invention provides a pneumatic cooling parameter optimization method for a magnetic suspension natural gas differential pressure generator, relates to the technical field of natural gas differential pressure power generation equipment, and designs a magnetic suspension natural gas differential pressure generator, in which a centripetal turbine type impeller structure can efficiently convert natural gas differential pressure energy into mechanical energy. Wherein the fairing adopts a sphere-like streamline design and is provided with an annular hole, the air flow is shunted to realize magnetic bearing cooling and magnetic coupling isolation, the air flow is separated and combined to flow through a multi-air-flow-channel design, and the heat dissipation effect is enhanced. Meanwhile, the pneumatic simulation precision is improved through a self-adaptive grid technology and a multi-scale turbulence model; a heuristic dynamic programming algorithm and a utility function are utilized, an empirical playback method is combined to iteratively optimize a control input quantity, namely a structure parameter, and the structure parameter in the magnetic suspension natural gas differential pressure generator can be adjusted based on the optimized control input quantity so as to improve the performance of the magnetic suspension natural gas differential pressure generator.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas pressure differential power generation equipment, in particular to a method for optimizing aerodynamic cooling parameters of a magnetically suspended natural gas pressure differential generator. Background Art

[0002] Current natural gas differential pressure power generation systems commonly use mechanical bearings to support the rotor. The physical contact characteristics of these bearings result in friction losses as high as 0.05-0.15 (ISO 4378 standard), resulting in energy conversion efficiency losses of 8%-12%. Furthermore, the nonlinear characteristics of the mechanical bearing's oil film stiffness can easily induce subsynchronous vibrations, with amplitude amplification factors reaching 5-8 times in the critical speed range. Annual maintenance costs account for 15%-20% of the total equipment cost. While magnetic levitation technology can eliminate friction losses, natural gas differential pressure power generation faces multiple coupling challenges. Under high pressure differential conditions (>6 MPa), the gas-solid thermal coupling effect is significant, making it difficult for traditional magnetic bearings to suppress vortex instability (amplitude >50 μm) caused by flow field pulsations. Furthermore, the interplay between magnetic pole layout and cooling channel design results in insufficient heat dissipation power density (<200 W / cm²). Magnetic saturation effects intensify when coil temperature rises exceed 80 K, limiting the system's long-term stability.

[0003] With the widespread adoption of natural gas energy, natural gas differential pressure power generation technology has attracted significant attention due to its ability to effectively utilize the pressure differential energy captured within gas pipelines. Traditional natural gas differential pressure generators typically utilize mechanical bearings to support the rotor, resulting in significant friction losses, high maintenance costs, and a short lifespan. Furthermore, existing equipment, most of which utilize a separate generator and expander structure, lacks optimal aerodynamic cooling coordination. This makes it difficult to effectively control the temperature rise of the stator windings and stator in high-temperature environments, impacting operational stability and power generation efficiency.

[0004] In terms of aerodynamic design, conventional CFD (computational fluid dynamics) simulation methods often use boundary layer meshing and physical field-controlled meshing, making it difficult to achieve high-precision simulations of high-speed, complex airflow regions and complex boundaries, resulting in large deviations in pressure drop predictions. Furthermore, existing single turbulence models cannot accurately describe both large-scale turbulence and the separation characteristics of the near-wall boundary layer, limiting the scope for optimizing aerodynamic performance. In terms of cooling structure design, traditional solutions often rely on external cooling systems or independent heat dissipation systems, which not only increases structural complexity but also affects the energy efficiency of natural gas. Summary of the Invention

[0005] In response to the problems of high structural complexity and the impact on the energy utilization efficiency of natural gas, the present invention aims to propose a method for optimizing the aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator, comprising: Step 1: Construct a three-dimensional model of a magnetically levitated natural gas pressure differential generator, wherein the magnetically levitated natural gas pressure differential generator includes an impeller, a stator, a magnetic bearing mechanism, a fairing, a tubular casing, and multiple gas flow channels. From the outside to the inside, the magnetically levitated natural gas pressure differential generator comprises a tubular casing, a fairing, and a magnetic bearing mechanism. The tubular casing includes an inlet casing, a pressure casing, and an outlet casing. The inlet casing and the pressure casing are fixed by rivets, and the pressure casing and the outlet casing are fixed by rivets. The magnetic bearing mechanism includes a rotor shaft and two bearing sub-mechanisms, with a stator disposed between the two bearing sub-mechanisms. The stator is an annular permanent magnet with a deep groove design and is fixed inside the pressure-bearing casing by embedding. The two bearing sub-mechanisms are provided with fairings on the outside. The fairings are axially protruding spherical streamlined structures. A plurality of circular holes are arranged in a ring around the axial center point of the fairings. The fairings are fixed to the inside of the pressure-bearing casing by rivets. The impeller is a centripetal turbine structure, fixed to the rotor shaft by interlocking, and located in the outlet casing. From the pressure casing to the outlet casing, the outlet casing adopts a gradually narrowing design at the impeller inlet. The multiple gas flow channels include an inner flow channel and an outer flow channel. The inner flow channel is a flow channel that passes through the circular hole of the fairing and passes through the area where the magnetic bearing mechanism is located. The outer flow channel is a flow channel in the area outside the fairing inside the tubular casing. Step 2: Based on the three-dimensional model, CFD simulation is performed on the process of natural gas passing through the magnetic levitation natural gas pressure differential generator to obtain the flow field distribution characteristics and temperature field characteristics of the natural gas flowing inside the magnetic levitation natural gas pressure differential generator, as well as the actual values ​​of the stator electromagnetic performance, the actual values ​​of the rotor electromagnetic performance, the actual values ​​of the stator mechanical strength, and the actual values ​​of the rotor mechanical strength. The flow field distribution characteristics and temperature field characteristics include the Mach number, local temperature gradient, Reynolds number, and velocity vector change in the internal region of the magnetic levitation natural gas pressure differential generator; Step 3: Based on the Mach number, local temperature gradient, Reynolds number, and velocity vector variation of the internal area of ​​the magnetic levitation natural gas pressure differential generator, the target grid is constructed using adaptive meshing technology; Step 4: For each grid area in the target grid, construct a turbulence model based on the Reynolds number obtained in step 2; Step 5: Extract the turbulence model of all grid areas in the target grid to obtain parameter feature vectors, which include the temperature rise of the winding, the temperature rise of the stator, and the pressure drop of the natural gas passing through the magnetic levitation natural gas pressure differential generator; Step 6: Calculate a utility value based on the temperature rise of the windings, the temperature rise of the stator, and the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator. Then, calculate a control input based on the utility value. Determine whether the utility value is less than or equal to a preset threshold. If the utility value is less than or equal to the preset threshold, use the calculated control input as the optimized control input. The optimized control input is used to adjust the structural parameters of the magnetic levitation natural gas pressure differential generator. If the utility value is greater than the preset threshold, return to step 3.

[0006] Optionally, the bearing sub-mechanism includes an axial magnetic levitation bearing, a radial magnetic levitation bearing and a protective bearing. The two bearing sub-mechanisms are installed at both ends of the rotor shaft. The two ends of the rotor shaft are respectively fixed to the inside of the pressure-bearing casing through bearing seats. The rotor shaft is connected to the bearing sub-mechanism through a tightening sleeve. From the center of the rotor shaft to both ends, there are radial magnetic levitation bearings, axial magnetic levitation bearings and protective bearings respectively. The outer ring of the protective bearing, the outer ring of the axial magnetic levitation bearing and the outer ring of the radial magnetic levitation bearing are welded and fixed to the inside of the fairing.

[0007] Optionally, step 3 specifically includes: For the area inside the magnetic levitation natural gas pressure differential generator with a Mach number greater than or equal to 0.6, a first-size grid is used; for the area with a Mach number greater than or equal to 0.3 and less than 0.6, a second-size grid is used; for the area with a Mach number less than 0.3, a third-size grid is used, where the first size is smaller than the second size, and the second size is smaller than the third size. A boundary layer refinement grid corrected by a wall function is used to obtain the initial grid; for the area with a local temperature gradient greater than or equal to 100 K / m in the initial grid, a hexahedral dominant structure grid is used, and 2 or 3 layers are automatically encrypted at the boundary, with the maximum local grid size not exceeding 0.3 mm, thereby obtaining the first grid; for the area in the first grid where the velocity vector change is less than 0.5 m / s, a structured coarse grid is used to replace it, thereby obtaining the target grid.

[0008] Optionally, step 4 specifically includes: For each grid area in the target grid, determine whether the Reynolds number in the grid area is greater than or equal to 10 4 , the Reynolds number in the grid area is greater than or equal to 10 4 In the case of a k-ε turbulence model, the Reynolds number in the grid area is less than 10 4 In the case of , the k-ω turbulence model is constructed in this grid area.

[0009] Optionally, in step 6, the utility value is calculated based on the temperature rise of the winding, the temperature rise of the stator, and the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator, specifically by the following formula: ; in, represents the utility value, Indicates the difference between the winding temperature rise at time t and the preset winding temperature rise, Indicates the difference between the stator temperature rise at time t and the preset stator temperature rise, It represents the difference between the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator at time t and the preset pressure drop. is the deviation between the actual value of the stator electromagnetic performance and the preset target value, is the deviation between the actual value of the rotor electromagnetic performance and the preset target value, Indicates the deviation between the actual value of the stator mechanical strength and the preset target value. Indicates the deviation between the actual value of the rotor mechanical strength and the preset target value. represents the temperature rise weight, represents the pressure drop weight, Represents mechanical weight, represents electromagnetic weight.

[0010] Optionally, calculating the control input based on the utility value in step 6 specifically includes: Step A1: Define state variables , the state quantity Expressed as: ; in, Indicates the deviation between the actual value of the stator mechanical strength and the preset target value. Indicates the deviation between the actual value of the rotor mechanical strength and the preset target value. Indicates the difference between the winding temperature rise at time t and the preset winding temperature rise, Indicates the difference between the stator temperature rise at time t and the preset stator temperature rise, Indicates the difference between the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator at time t and the preset pressure drop; Step A2: Based on utility value and state quantity , combined with the formula to minimize the cost function, the control input is calculated .

[0011] Optionally, the formula for minimizing the cost function is expressed as: ; in, represents the discount factor, represents the cost value at time t, express The cost value at the moment, Indicates a time interval.

[0012] The beneficial effects of adopting the above technical solution are: The present invention designs a magnetically levitated natural gas pressure differential generator. The centripetal turbine impeller structure in the magnetically levitated natural gas pressure differential generator can achieve the purpose of efficiently converting the natural gas pressure differential energy into mechanical energy during the operation of the magnetically levitated natural gas pressure differential generator. The present invention also designs a fairing that adopts a spherical streamlined design and is equipped with annular holes. The split airflow achieves magnetic bearing cooling and magnetic coupling isolation. The multi-gas flow channel design allows the airflow to be separated and combined, enhancing the heat dissipation effect. At the same time, based on the structure of the magnetically levitated natural gas pressure differential generator, the present invention provides an aerodynamic cooling parameter optimization method for the magnetically levitated natural gas pressure differential generator. The method improves the aerodynamic simulation accuracy through adaptive grid technology and multi-scale turbulence models. The method utilizes a heuristic dynamic programming algorithm and a utility function, combined with an experience replay method, to iteratively optimize the control input, i.e., the structural parameters. Based on the optimized control input, the structural parameters in the magnetically levitated natural gas pressure differential generator can be adjusted to improve the performance of the magnetically levitated natural gas pressure differential generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of a flow chart of a method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to an embodiment of the present invention; Figure 2 Schematic diagram of the structure of a magnetically suspended natural gas pressure differential generator in an embodiment of the present invention; Figure 3 is a front view of a fairing in an embodiment of the present invention; In the figure, 1-impeller, 2-stator, 3-magnetic bearing mechanism, 4-fairing, 5-tubular casing, 301-rotor shaft, 302-bearing sub-mechanism, 3021-axial magnetic bearing, 3022-radial magnetic bearing, 3023-protective bearing, 501-inlet casing, 502-pressure casing, 503-outlet casing. DETAILED DESCRIPTION

[0014] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0015] In view of the problems existing in the prior art, the present invention provides a method for optimizing the aerodynamic cooling parameters of a magnetically suspended natural gas pressure differential generator. Figure 1 , which may include the following steps: Step 1: Construct a 3D model of the magnetically levitated natural gas pressure differential generator, combining Figure 2The magnetic levitation natural gas pressure differential generator includes an impeller 1, a stator 2, a magnetic levitation bearing mechanism 3, a fairing 4, a tubular casing 5, and multiple gas flow channels. From the outside to the inside, the magnetic levitation natural gas pressure differential generator is composed of a tubular casing 5, a fairing 4, and a magnetic levitation bearing mechanism 3. The tubular casing 5 includes an inlet casing 501, a pressure casing 502, and an outlet casing 503. The inlet casing 501 and the pressure casing 502 are fixed by rivets, and the pressure casing 502 and the outlet casing 503 are fixed by rivets. The magnetic bearing mechanism 3 includes a rotor shaft 301 and two bearing sub-mechanisms 302. A stator 2 is disposed between the two bearing sub-mechanisms 302. The stator 2 is an annular permanent magnet with a deep groove design. The stator 2 is fixed to the inside of the pressure-bearing casing 502 by embedding. The bearing sub-mechanism 302 includes an axial magnetic suspension bearing 3021, a radial magnetic suspension bearing 3022 and a protective bearing 3023. The two bearing sub-mechanisms 302 are installed at both ends of the rotor shaft 301. The two ends of the rotor shaft 301 are fixed to the inside of the pressure-bearing casing 502 through bearing seats. The rotor shaft 301 is connected to the bearing sub-mechanism 302 through a tightening sleeve and drives the power generation. From the center of the rotor shaft 301 to the two ends are the radial magnetic suspension bearing 3022, the axial magnetic suspension bearing 3021 and the protective bearing 3023. The outer ring of the protective bearing 3023, the outer ring of the axial magnetic suspension bearing 3021 and the outer ring of the radial magnetic suspension bearing 3022 are welded and fixed to the inside of the fairing 4.

[0016] The two bearing sub-mechanisms 302 are provided with fairings 4 on the outside. The fairings 4 are axially protruding spherical streamlined structures. Figure 3 A plurality of circular holes are arranged in an annular manner at the axial center point of the fairing 4. The diameter of the circular holes can be 4 mm, which are used to guide the airflow through the interior of the magnetic bearing mechanism 3 to achieve heat dissipation and effectively reduce the magnetic coupling between the magnetic bearing and the stator 2. The fairing 4 is fixed to the interior of the pressure casing 502 by rivets; The impeller 1 is a centripetal turbine structure, fixed to the rotor shaft 301 by interlocking means. The impeller 1 is located in the outlet casing 503. From the pressure casing 502 to the outlet casing 503, the outlet casing 503 adopts a gradually narrowing design at the inlet of the impeller 1. The impeller 1 is used to efficiently convert the pressure difference energy of the natural gas into the mechanical energy of the rotor shaft 301. The multi-gas flow channel includes an inner flow channel and an outer flow channel, combined with Figure 2 , Figure 2The arrows in the figure indicate the direction of gas flow. The inner flow channel is the flow channel that passes through the circular hole of the fairing 4 and the area where the magnetic bearing mechanism 3 is located. The outer flow channel is the flow channel in the area outside the fairing 4 inside the tubular housing 5. Through the above design, the heat dissipation effect of the airflow inside the unit is enhanced and the energy conversion efficiency is improved.

[0017] Step 2: Based on the three-dimensional model, CFD simulation is performed on the process of natural gas passing through the magnetic levitation natural gas pressure differential generator to obtain the flow field distribution characteristics and temperature field characteristics of the natural gas flowing inside the magnetic levitation natural gas pressure differential generator, as well as the actual values ​​of the stator electromagnetic performance, the actual values ​​of the rotor electromagnetic performance, the actual values ​​of the stator mechanical strength, and the actual values ​​of the rotor mechanical strength. The flow field distribution characteristics and temperature field characteristics include the Mach number, local temperature gradient, Reynolds number, and velocity vector change in the internal region of the magnetic levitation natural gas pressure differential generator; Step 3: Based on the Mach number, local temperature gradient, Reynolds number, and velocity vector variation of the internal area of ​​the magnetic levitation natural gas pressure differential generator, the target grid is constructed using adaptive meshing technology; For regions within the magnetically levitated natural gas pressure differential generator with Mach numbers greater than or equal to 0.6, which primarily occur at the impeller front and high-speed airflow contraction channel, a first-size mesh is used. For regions with Mach numbers greater than or equal to 0.3 and less than 0.6, including the stator channel inlet and near the fairing annular hole, a second-size mesh is used. For regions with Mach numbers less than 0.3, including the structural cavity and low-speed recirculation area, a third-size mesh is used. The first size is smaller than the second size, which in turn is smaller than the third size. A boundary layer refinement mesh modified with a wall function (y+ controlled within 30) is used, with a first layer thickness of no more than 0.05 mm to ensure the accuracy of the temperature gradient distribution simulation. This initial mesh is obtained. In specific implementations, the first size can be in the range of 0.2 mm to 0.4 mm to capture shock waves and strong turbulence effects. The second size can be in the range of 0.5 mm to 1.0 mm, and the third size can be in the range of 1.5 mm to 2.5 mm. For areas in the initial grid where the local temperature gradient is greater than or equal to 100 K / m, namely heating areas such as windings, stators, and magnetic bearings, a hexahedron-dominated structural grid is used, and 2 or 3 layers are automatically encrypted at the boundaries. The maximum local grid size does not exceed 0.3 mm, thus obtaining the first grid; for areas in the first grid where the velocity vector change is less than 0.5 m / s, a structured coarse grid is used to replace it to reduce the number of simulation units and improve the overall simulation efficiency; mesh type and quality control: mainly adopt a multi-region partitioning adaptive partitioning strategy, mixed with structured hexahedron and unstructured tetrahedron / prism grids to ensure that the grid orthogonality is better than 0.7 and the minimum twist angle is greater than 20° to avoid numerical dissipation, thus obtaining the target grid.

[0018] Step 4: For each grid area in the target grid, construct a turbulence model based on the Reynolds number obtained in step 2; For each grid area in the target grid, determine whether the Reynolds number in the grid area is greater than or equal to 10 4 , the Reynolds number in the grid area is greater than or equal to 10 4 In the case of a k-ε turbulence model, the Reynolds number in the grid area is less than 10 4 In the case of , the k-ω turbulence model is constructed in this grid area.

[0019] Step 5: Extract the turbulence model of all grid areas in the target grid to obtain parameter feature vectors. The parameter feature vectors include the temperature rise of the winding, the temperature rise of the stator, and the pressure drop of natural gas through the magnetic levitation natural gas pressure differential generator. The parameter feature vectors can also include the local Reynolds number, vorticity distribution, pressure gradient change trend, heat flux density, and velocity vector distribution.

[0020] In a specific implementation process, the present invention compresses the dimension of the parameter feature vector using a dimensionality reduction technique to form a state input vector for subsequent heuristic dynamic optimization.

[0021] Step 6: Calculate a utility value based on the temperature rise of the windings, the temperature rise of the stator, and the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator. Then, calculate a control input based on the utility value. Determine whether the utility value is less than or equal to a preset threshold. If the utility value is less than or equal to the preset threshold, use the calculated control input as the optimized control input. The optimized control input is used to adjust the structural parameters of the magnetic levitation natural gas pressure differential generator. If the utility value is greater than the preset threshold, return to step 3.

[0022] The utility value is calculated based on the temperature rise of the winding, the temperature rise of the stator, and the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator, which is specifically achieved through the following formula: ; in, represents the utility value, Indicates the difference between the winding temperature rise at time t and the preset winding temperature rise, Indicates the difference between the stator temperature rise at time t and the preset stator temperature rise, It represents the difference between the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator at time t and the preset pressure drop. is the deviation between the actual value of the stator electromagnetic performance and the preset target value, is the deviation between the actual value of the rotor electromagnetic performance and the preset target value, Indicates the deviation between the actual value of the stator mechanical strength and the preset target value. Indicates the deviation between the actual value of the rotor mechanical strength and the preset target value. represents the temperature rise weight, represents the pressure drop weight, Represents mechanical weight, represents electromagnetic weight.

[0023] The calculation of control input based on utility value specifically includes: Step A1: Define state variables , the state quantity Expressed as: ; in, Indicates the deviation between the actual value of the stator mechanical strength and the preset target value. Indicates the deviation between the actual value of the rotor mechanical strength and the preset target value. Indicates the difference between the winding temperature rise at time t and the preset winding temperature rise, Indicates the difference between the stator temperature rise at time t and the preset stator temperature rise, Indicates the difference between the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator at time t and the preset pressure drop; Step A2: Based on utility value and state quantity , combined with the formula to minimize the cost function, the control input is calculated .

[0024] The formula for minimizing the cost function is expressed as: ; in, represents the discount factor, represents the cost value at time t, express The cost value at the moment, Indicates a time interval.

[0025] Furthermore, the present invention adopts the experience playback method to store the state changes after the motor structure parameters are adjusted, the control input and the corresponding utility value as a tuple , stored in the ER database G; the sampling probability is determined based on the change in utility value or the degree of proximity to the target value. If a set of structural parameters is adjusted to significantly improve the cooling efficiency, the priority of the corresponding tuple is increased; the sampling probability of the kth tuple is: ; ; in, represents the probability that the kth tuple is sampled, represents the weight of the k-th tuple, represents the rank of the k-th tuple, Determined by the formula for calculating the utility value, L represents the number of iterations, α is a hyperparameter, express to the power of α.

[0026] The key technical points of the present invention are: 1. Design a centripetal turbine impeller structure to convert the natural gas pressure differential into mechanical energy. Use ANSYS software to model the motor structure. Adaptive mesh technology and multi-scale turbulence models are used to improve aerodynamic simulation accuracy and achieve optimal aerodynamic performance. 2. The airflow path inside the pressure differential generator has been designed. The fairing adopts a spherical streamlined design and is equipped with annular holes to divert the airflow to achieve magnetic bearing cooling. The multi-gas flow channel design allows the airflow to be separated and combined to enhance the heat dissipation effect. 3. A sealing gasket is used at the rear end of the pressure difference generator to change the airflow path, concentrating the gas on the low-pressure side to the force-bearing side of the turbine impeller, thereby further improving the pressure difference energy conversion rate.

[0027] Compared with the prior art, the advantages of the present invention are: 1. The centripetal turbine impeller structure proposed in the present invention can achieve the purpose of efficiently converting the pressure difference energy of natural gas into mechanical energy during the operation of the magnetic levitation pressure difference generator; 2. The air flow path inside the pressure difference generator and the spherical streamlined fairing structure proposed in the present invention can optimize the gas pressure drop and motor temperature rise, reduce the degree of magnetic coupling, and improve the heat dissipation efficiency and energy conversion efficiency.

[0028] The above description is merely an illustration of the preferred embodiments of the present disclosure and the technical principles employed. Those skilled in the art should understand that the scope of the invention encompassed by the embodiments of the present disclosure is not limited to technical solutions formed by specific combinations of the aforementioned technical features. It also encompasses other technical solutions formed by any combination of the aforementioned technical features or their equivalents, without departing from the aforementioned inventive concept. For example, a technical solution formed by replacing the aforementioned features with (but not limited to) technical features having similar functions disclosed in the embodiments of the present disclosure.

Claims

1. A method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator, characterized in that: include: Step 1: Construct a three-dimensional model of a magnetically levitated natural gas pressure differential generator, wherein the magnetically levitated natural gas pressure differential generator includes an impeller, a stator, a magnetic bearing mechanism, a fairing, a tubular casing, and multiple gas flow channels. From the outside to the inside, the magnetically levitated natural gas pressure differential generator comprises a tubular casing, a fairing, and a magnetic bearing mechanism. The tubular casing includes an inlet casing, a pressure casing, and an outlet casing. The inlet casing and the pressure casing are fixed by rivets, and the pressure casing and the outlet casing are fixed by rivets. The magnetic bearing mechanism includes a rotor shaft and two bearing sub-mechanisms, with a stator disposed between the two bearing sub-mechanisms. The stator is an annular permanent magnet with a deep groove design and is fixed inside the pressure-bearing casing by embedding. The two bearing sub-mechanisms are provided with fairings on the outside. The fairings are axially protruding spherical streamlined structures. A plurality of circular holes are arranged in a ring around the axial center point of the fairings. The fairings are fixed to the inside of the pressure-bearing casing by rivets. The impeller is a centripetal turbine structure, fixed to the rotor shaft by interlocking, and located in the outlet casing. From the pressure casing to the outlet casing, the outlet casing adopts a gradually narrowing design at the impeller inlet. The multiple gas flow channels include an inner flow channel and an outer flow channel. The inner flow channel is a flow channel that passes through the circular hole of the fairing and passes through the area where the magnetic bearing mechanism is located. The outer flow channel is a flow channel in the area outside the fairing inside the tubular casing. Step 2: Based on the three-dimensional model, CFD simulation is performed on the process of natural gas passing through the magnetic levitation natural gas pressure differential generator to obtain the flow field distribution characteristics and temperature field characteristics of the natural gas flowing inside the magnetic levitation natural gas pressure differential generator, as well as the actual values ​​of the stator electromagnetic performance, the actual values ​​of the rotor electromagnetic performance, the actual values ​​of the stator mechanical strength, and the actual values ​​of the rotor mechanical strength. The flow field distribution characteristics and temperature field characteristics include the Mach number, local temperature gradient, Reynolds number, and velocity vector change in the internal region of the magnetic levitation natural gas pressure differential generator; Step 3: Based on the Mach number, local temperature gradient, Reynolds number, and velocity vector variation of the internal area of ​​the magnetic levitation natural gas pressure differential generator, the target grid is constructed using adaptive meshing technology; Step 4: For each grid area in the target grid, construct a turbulence model based on the Reynolds number obtained in step 2; Step 5: Extract the turbulence model of all grid areas in the target grid to obtain parameter feature vectors, which include the temperature rise of the winding, the temperature rise of the stator, and the pressure drop of the natural gas passing through the magnetic levitation natural gas pressure differential generator; Step 6: Calculate a utility value based on the temperature rise of the windings, the temperature rise of the stator, and the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator. Then, calculate a control input based on the utility value. Determine whether the utility value is less than or equal to a preset threshold. If the utility value is less than or equal to the preset threshold, use the calculated control input as the optimized control input. The optimized control input is used to adjust the structural parameters of the magnetic levitation natural gas pressure differential generator. If the utility value is greater than the preset threshold, return to step 3.

2. The method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to claim 1, characterized in that: The bearing sub-mechanism includes an axial magnetic levitation bearing, a radial magnetic levitation bearing and a protective bearing. The two bearing sub-mechanisms are installed at both ends of the rotor shaft. The two ends of the rotor shaft are respectively fixed to the inside of the pressure-bearing casing through bearing seats. The rotor shaft is connected to the bearing sub-mechanism through a tightening sleeve. From the center of the rotor shaft to the two ends, there are radial magnetic levitation bearings, axial magnetic levitation bearings and protective bearings respectively. The outer ring of the protective bearing, the outer ring of the axial magnetic levitation bearing and the outer ring of the radial magnetic levitation bearing are welded and fixed to the inside of the fairing.

3. The method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to claim 1, characterized in that: Step 3 specifically includes: For the area inside the magnetic levitation natural gas pressure differential generator with a Mach number greater than or equal to 0.6, a first-size grid is used; for the area with a Mach number greater than or equal to 0.3 and less than 0.6, a second-size grid is used; for the area with a Mach number less than 0.3, a third-size grid is used, where the first size is smaller than the second size, and the second size is smaller than the third size. A boundary layer refinement grid corrected by a wall function is used to obtain the initial grid; for the area with a local temperature gradient greater than or equal to 100 K / m in the initial grid, a hexahedral dominant structure grid is used, and 2 or 3 layers are automatically encrypted at the boundary, with the maximum local grid size not exceeding 0.3 mm, thereby obtaining the first grid; for the area in the first grid where the velocity vector change is less than 0.5 m / s, a structured coarse grid is used to replace it, thereby obtaining the target grid.

4. The method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to claim 1, characterized in that: Step 4 specifically includes: For each grid area in the target grid, determine whether the Reynolds number in the grid area is greater than or equal to 10 4 , the Reynolds number in the grid area is greater than or equal to 10 4 In the case of a k-ε turbulence model, the Reynolds number in the grid area is less than 10 4 In the case of , the k-ω turbulence model is constructed in this grid area.

5. The method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to claim 1, characterized in that: In step 6, the utility value is calculated based on the temperature rise of the winding, the temperature rise of the stator, and the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator, which is specifically achieved through the following formula: ； in, represents the utility value, Indicates the difference between the winding temperature rise at time t and the preset winding temperature rise, Indicates the difference between the stator temperature rise at time t and the preset stator temperature rise, It represents the difference between the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator at time t and the preset pressure drop. is the deviation between the actual value of the stator electromagnetic performance and the preset target value, is the deviation between the actual value of the rotor electromagnetic performance and the preset target value, Indicates the deviation between the actual value of the stator mechanical strength and the preset target value. Indicates the deviation between the actual value of the rotor mechanical strength and the preset target value. represents the temperature rise weight, represents the pressure drop weight, Represents mechanical weight, represents electromagnetic weight.

6. The method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to claim 1, characterized in that: The calculation of the control input based on the utility value in step 6 specifically includes: Step A1: Define state variables , the state quantity Expressed as: ； in, Indicates the deviation between the actual value of the stator mechanical strength and the preset target value. Indicates the deviation between the actual value of the rotor mechanical strength and the preset target value. Indicates the difference between the winding temperature rise at time t and the preset winding temperature rise, Indicates the difference between the stator temperature rise at time t and the preset stator temperature rise, Indicates the difference between the pressure drop of natural gas passing through the magnetic levitation natural gas pressure differential generator at time t and the preset pressure drop; Step A2: Based on utility value and state quantity , combined with the formula to minimize the cost function, the control input is calculated .

7. The method for optimizing aerodynamic cooling parameters of a magnetically levitated natural gas pressure differential generator according to claim 6, characterized in that: The formula for minimizing the cost function is expressed as: ； in, represents the discount factor, represents the cost value at time t, express The cost value at the moment, Indicates a time interval.

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