Internal flow numerical simulation analysis method of dense-phase carbon dioxide centrifugal pump

Abstract

An internal flow numerical simulation analysis method of a dense-phase carbon dioxide centrifugal pump comprises the steps that geometric modeling is conducted on all stages of the dense-phase carbon dioxide centrifugal pump to obtain a geometric model, and a computational grid is generated for the geometric model; a dense-phase carbon dioxide thermophysical property table is established, and CFD models of all stages of the dense-phase carbon dioxide centrifugal pump are established based on the computational grid and the dense-phase carbon dioxide thermophysical property table; carrying out CFD iterative calculation on the dense-phase carbon dioxide centrifugal pump step by step based on the CFD model, and outputting flow field data of each stage of the multi-stage dense-phase carbon dioxide centrifugal pump; extracting average flow parameters and thermal parameters of inlet and outlet sections of each stage from the flow field data of each stage; calculating the performance parameters of each stage of the dense-phase carbon dioxide centrifugal pump according to the average flow parameters and the thermal parameters of the inlet and outlet sections of each stage; and calculating the performance parameters of the whole dense-phase carbon dioxide centrifugal pump based on the energy parameters of all levels.

Description

Technical Field

[0001] The invention relates to the technical field of dense phase carbon dioxide fluid, and in particular to an internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump. Background Art

[0002] Dense phase carbon dioxide (CO 2 ) pump is a core component of carbon capture, utilization and storage (CCUS). Compared with supercritical CO 2 Compression can save nearly half of the compression power consumption. The dense phase carbon dioxide centrifugal pump converts the CO in a dense phase state into 2 Injecting the gas underground after increasing the pressure to tens of MPa is the key to the success of CCUS technology. However, the inlet state of the dense phase CO2 centrifugal pump is close to the critical point, and the compression process deviates from the incompressible state, which poses a challenge to the numerical simulation, performance analysis and design of the internal flow of the pump. 2 Computational fluid dynamics (CFD) analysis was performed using water with similar density as the working fluid. This method can provide a preliminary performance estimate for dense phase CO2 centrifugal pumps. However, due to the neglect of dense phase CO2 2 The actual thermophysical properties and compressibility of the dense phase CO2 are considered, which may cause flow capture distortion and large performance prediction deviation. 2 How to consider the near-critical dense phase CO in numerical flow simulation? 2 The real thermophysical properties and compressibility, and the establishment of corresponding performance analysis methods on this basis, are of great significance to improving the research and development and design level of dense phase carbon dioxide centrifugal pumps.

[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention proposes a method for numerical simulation analysis of the internal flow of a dense phase carbon dioxide centrifugal pump. 2 The influence of the actual thermophysical properties and compressibility of the working fluid is taken into account to improve the prediction accuracy of the numerical simulation, thereby providing reliable data for the design and performance optimization of dense phase carbon dioxide centrifugal pumps. At the same time, in view of the large size of computer memory required for numerical simulation of multi-stage centrifugal pumps, a step-by-step calculation strategy is proposed to greatly reduce computer memory overhead and significantly improve simulation performance.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for numerical simulation analysis of internal flow of a dense phase carbon dioxide centrifugal pump includes:

[0007] Step 1: geometrically modeling each stage of the dense phase carbon dioxide centrifugal pump to obtain a geometric model, wherein the geometric model includes a suction chamber and a plurality of single-stage flow passages, wherein the single-stage flow passages include an impeller and inter-stage stationary components;

[0008] Step 2: Generate a computational grid for the geometric model;

[0009] Step 3: Establish a dense phase carbon dioxide thermophysical property table, which is a data table for interpolating carbon dioxide temperature and static pressure based on the state equation and transmission characteristics;

[0010] Step 4: Establishing a CFD model of each stage of a dense phase carbon dioxide centrifugal pump based on the computational grid and the dense phase carbon dioxide thermophysical property table;

[0011] Step 5: Based on the CFD model, CFD iterative calculation is performed on the dense phase carbon dioxide centrifugal pump stage by stage, and flow field data of each stage of the multi-stage dense phase carbon dioxide centrifugal pump is output;

[0012] Step 6: Change the parameter values ​​of the CFD model outlet boundary conditions and repeat step 5 to obtain the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions;

[0013] Step 7: Extract the average flow parameters and thermal parameters of the inlet and outlet sections of each level from the flow field data of each level;

[0014] Step 8: Calculate the performance parameters of each stage of the dense phase carbon dioxide centrifugal pump based on the average flow parameters and thermodynamic parameters of the inlet and outlet sections of each stage;

[0015] Step 9: Calculate the performance parameters of the dense phase carbon dioxide centrifugal pump based on the energy parameters of each level;

[0016] Step 10: Based on the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions obtained in step 6, steps 7 to 9 are repeated to obtain the overall performance parameters of the dense phase carbon dioxide centrifugal pump under different working conditions.

[0017] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, in step 1, the various stages of the dense phase carbon dioxide centrifugal pump are geometrically modeled using Soildworks software.

[0018] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, in step 2, ANSYS-ICEM software is used to generate a computational grid for the geometric model.

[0019] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, an unstructured grid is used to spatially discretize the calculation domain of the geometric model.

[0020] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, in the dense phase carbon dioxide thermophysical property table, the static pressure range is set to 6 to 25 MPa, the temperature range is 260 to 310 K, and the interpolation resolution is 100×100.

[0021] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, step 4 includes:

[0022] Step a1: importing the computational grid;

[0023] Step a2: importing the dense phase carbon dioxide thermal property table;

[0024] Step a3: Set the control equation to be solved;

[0025] Step a4: Setting the turbulence model;

[0026] Step a5: Set the numerical format of the convection term and diffusion term of the control equation;

[0027] Step a6: Setting boundary conditions and dynamic and static interface processing methods;

[0028] Step a7: Setting the pressure-velocity solution method;

[0029] Step a8: Setting numerical iteration control parameters and target residual values;

[0030] Step a9: Start iterative calculation until the equation residual reaches the set value.

[0031] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, a computational grid and a dense phase carbon dioxide thermophysical property table are imported into the ANSYS-CFX software pre-processing, the control equation is the Reynolds averaged Navier-Stokes equation, the turbulence model is the SST k-ω to close the equation group, the numerical format of the convection term of the control equation is set to the second-order high-resolution upwind format discretization, the diffusion term is discretized using the second-order center format, the total temperature, total pressure and incoming flow direction of the inlet boundary are set, the mass flow rate of the outlet boundary is set, the solid wall boundary is set to the adiabatic no-slip condition, the discrete pressure-velocity coupling solution method is set, the numerical iteration control parameter Courant number is equal to 50, and the target residual value is 1×10 -4 .

[0032] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, the average flow parameters and thermodynamic parameters include average static pressure, density, absolute velocity and stagnation enthalpy.

[0033] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, the performance parameters include polytropic index, work, head and efficiency.

[0034] In the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, the polynomial index expression is:

[0035]

[0036] Where p and ρ represent static pressure and density respectively; subscript i represents the i-th stage, in and out represent the average state parameters of the inlet and outlet sections of the stage respectively;

[0037] The work expression is:

[0038]

[0039] Where V represents the absolute speed,

[0040] The lift expression is:

[0041]

[0042] In the formula, g represents the acceleration due to gravity,

[0043] The efficiency expression is:

[0044]

[0045] Where W tot Indicates the total power consumption, h st represents the stagnation enthalpy.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] The present invention considers CO 2 The influence of the actual thermophysical properties and compressibility of the working fluid can improve the prediction accuracy of the numerical simulation, thereby providing reliable data for the design and performance optimization of dense phase carbon dioxide centrifugal pumps. At the same time, in view of the large size of computer memory required for numerical simulation of multi-stage centrifugal pumps, a step-by-step calculation strategy is proposed, which can significantly reduce computer memory overhead. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0049] In the attached picture:

[0050] Figure 1 It is a flow chart of a method for numerical simulation analysis of internal flow of a dense phase carbon dioxide centrifugal pump provided by the present invention;

[0051] Figure 2(a) to Figure 2(b) 2 is a schematic diagram of a dense phase carbon dioxide centrifugal pump model, wherein FIG2(a) is a geometric model and FIG2(b) is a single-stage flow channel model;

[0052] Figure 3(a) to Figure 3(b) 3 is a schematic diagram of the whole machine performance curve of an embodiment of the present invention, wherein FIG3(a) is a head curve and FIG3(b) is an efficiency curve.

[0053] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0054] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0055] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0056] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0057] like Figure 1 to Figure 3(b) As shown, the internal flow numerical simulation analysis method of the dense phase carbon dioxide centrifugal pump includes the following steps:

[0058] Step 1: geometrically modeling each stage of the dense phase carbon dioxide centrifugal pump to obtain a geometric model, wherein the geometric model includes a suction chamber and a plurality of single-stage flow passages, wherein the single-stage flow passages include an impeller and inter-stage stationary components;

[0059] Step 2: Generate a computational grid for the geometric model;

[0060] Step 3: Establish a dense phase carbon dioxide thermophysical property table, which is a data table for interpolating carbon dioxide temperature and static pressure based on the state equation and transmission characteristics;

[0061] Step 4: Establishing a CFD model of each stage of a dense phase carbon dioxide centrifugal pump based on the computational grid and the dense phase carbon dioxide thermophysical property table;

[0062] Step 5: Based on the CFD model, CFD iterative calculation is performed on the dense phase carbon dioxide centrifugal pump stage by stage, and flow field data of each stage of the multi-stage dense phase carbon dioxide centrifugal pump is output;

[0063] Step 6: Change the parameter values ​​of the CFD model outlet boundary conditions and repeat step 5 to obtain the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions;

[0064] Step 7: Extract the average flow parameters and thermal parameters of the inlet and outlet sections of each level from the flow field data of each level;

[0065] Step 8: Calculate the performance parameters of each stage of the dense phase carbon dioxide centrifugal pump based on the average flow parameters and thermodynamic parameters of the inlet and outlet sections of each stage;

[0066] Step 9: Calculate the performance parameters of the dense phase carbon dioxide centrifugal pump based on the energy parameters of each level;

[0067] Step 10: Based on the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions obtained in step 6, steps 7 to 9 are repeated to obtain the overall performance parameters of the dense phase carbon dioxide centrifugal pump under different working conditions.

[0068] In a preferred implementation of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, in step 1, the various stages of the dense phase carbon dioxide centrifugal pump are geometrically modeled using Soildworks software.

[0069] In a preferred implementation of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, in step 2, ANSYS-ICEM software is used to generate a computational grid for the geometric model.

[0070] In a preferred embodiment of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, an unstructured grid is used to spatially discretize the computational domain of the geometric model.

[0071] In a preferred embodiment of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, in the dense phase carbon dioxide thermophysical property table, the static pressure range is set to 6 to 25 MPa, the temperature range is 260 to 310 K, and the interpolation resolution is 100×100.

[0072] In a preferred embodiment of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, step 4 includes:

[0073] Step a1: importing the computational grid;

[0074] Step a2: importing the dense phase carbon dioxide thermal property table;

[0075] Step a3: Set the control equation to be solved;

[0076] Step a4: Setting the turbulence model;

[0077] Step a5: Set the numerical format of the convection term and diffusion term of the control equation;

[0078] Step a6: Setting boundary conditions and dynamic and static interface processing methods;

[0079] Step a7: Setting the pressure-velocity solution method;

[0080] Step a8: Setting numerical iteration control parameters and target residual values;

[0081] Step a9: Start iterative calculation until the equation residual reaches the set value.

[0082] In a preferred embodiment of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, a computational grid and a dense phase carbon dioxide thermophysical property table are imported into the ANSYS-CFX software pre-processing, the control equation is the Reynolds-averaged Navier-Stokes equation, the turbulence model is SST k-ω to close the equation group, the numerical format of the convection term of the control equation is set to the second-order high-resolution upwind format discretization, the diffusion term is discretized using the second-order center format, the total temperature, total pressure and incoming flow direction of the inlet boundary are set, the mass flow rate of the outlet boundary is set, the solid wall boundary is set to the adiabatic no-slip condition, the discrete pressure-velocity coupling solution method is set, the numerical iteration control parameter Courant number is equal to 50, and the target residual value is 1×10-4 .

[0083] In a preferred embodiment of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, the average flow parameters and thermodynamic parameters include average static pressure, density, absolute velocity and stagnation enthalpy.

[0084] In a preferred implementation of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, the performance parameters include polytropic index, work, head and efficiency.

[0085] In a preferred embodiment of the internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump, the polynomial index expression is:

[0086]

[0087] Where p and ρ represent static pressure and density respectively; subscript i represents the i-th stage, in and out represent the average state parameters of the inlet and outlet sections of the stage respectively;

[0088] The work expression is:

[0089]

[0090] Where V represents the absolute speed,

[0091] The lift expression is:

[0092]

[0093] In the formula, g represents the acceleration due to gravity,

[0094] The efficiency expression is:

[0095]

[0096] Where W tot Indicates the total power consumption, h st represents the stagnation enthalpy.

[0097] In one embodiment, the whole machine performance parameters include the whole machine head and the whole machine efficiency.

[0098] The whole machine head expression is:

[0099]

[0100] Wherein, N represents the number of stages of the multi-stage dense phase carbon dioxide centrifugal pump, and the subscript i represents the i-th stage.

[0101] The overall efficiency expression is:

[0102]

[0103] In one embodiment,

[0104] For better understanding, in an embodiment of an 11-stage dense phase carbon dioxide centrifugal pump, a method for analyzing the internal flow numerical simulation of a dense phase carbon dioxide centrifugal pump comprises the following steps:

[0105] Step 1: Use Soildworks software to geometrically model each stage of the dense phase carbon dioxide centrifugal pump. The overall geometry and single-stage geometry models are as follows: Figure 2(a) to Figure 2(b) shown.

[0106] Step 2: Use ANSYS-ICEM software to generate computational meshes for the various levels of geometric models.

[0107] Preferably, an unstructured grid is used to spatially discretize the computational domain of the geometric model.

[0108] Step 3: Establish a dense phase CO based on the National Institute of Standards and Technology (NIST) database 2 Thermal properties table.

[0109] Step 4: Preferably, the single-level grid described in step 2 and the dense phase CO described in step 3 are imported into the ANSYS-CFX software pre-processing. 2 Thermal properties table.

[0110] Step 5: Set the control equation to be solved as the Reynolds-averaged Navier-Stokes (RANS) equation. Preferably, set the turbulence model to SST k-ω to make the equation group closed.

[0111] Step 6: Preferably, the numerical format of the convection term of the control equation is set to a second-order high-resolution upwind discretization format, and the diffusion term is discretized using a second-order central format.

[0112] Step 7: Set the total temperature, total pressure and incoming flow direction of the inlet boundary, set the mass flow rate of the outlet boundary, and set the solid wall boundary to adiabatic no-slip conditions. Preferably, the dynamic and static interface processing method is set to the mixed plane method.

[0113] Step 8: Set the discrete pressure-velocity coupling solution method.

[0114] Step 9: Preferably, set the numerical iteration control parameter Courant number equal to 50.

[0115] Preferably, the target residual value is set to 1×10 -4 .

[0116] Step 10: Start iterative calculation until the equation residual reaches the set value.

[0117] Step 11: Based on the CFD model described in Steps 4 to 10, CFD iterative calculations are performed on the 11-stage dense phase carbon dioxide centrifugal pump stage by stage.

[0118] Step 12: Output the flow field data of each stage of the 11-stage dense phase carbon dioxide centrifugal pump using ANSYS-CFX software.

[0119] Step 13: Change the mass flow value of the outlet boundary of the CFD model, repeat steps 11 and 12, and obtain the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions.

[0120] Step 14: Extract the average static pressure, density, absolute velocity and stagnation enthalpy of each inlet and outlet section from the flow field data of each stage of the 11-stage dense phase carbon dioxide centrifugal pump output in step 12.

[0121] Step 15: Calculate the polytropic index, work, head and efficiency of each stage of the dense phase carbon dioxide centrifugal pump based on the parameters described in step 14.

[0122] Step 16: Calculate the polytropic index, work, head and efficiency of the dense phase carbon dioxide centrifugal pump according to the performance parameters of each level described in step 15.

[0123] Step 17: Based on the flow field data of the dense phase carbon dioxide centrifugal pump at different operating conditions obtained in step 13, repeat steps 14 to 16 to obtain the whole machine polynomial index, work, head and efficiency of the dense phase carbon dioxide centrifugal pump under different operating conditions. Draw a schematic diagram of the whole machine performance curve including head (pressure ratio), efficiency, etc. that varies with flow rate, as shown in Figure 3(a) to Figure 3(b) As shown, Q m，D , H D , η D They represent the design values ​​of mass flow rate, head and efficiency respectively.

[0124] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A method for numerical simulation analysis of the internal flow of a dense phase carbon dioxide centrifugal pump, characterized in that: The steps include: Step 1: geometrically modeling each stage of the dense phase carbon dioxide centrifugal pump to obtain a geometric model, wherein the geometric model includes a suction chamber and a plurality of single-stage flow passages, wherein the single-stage flow passages include an impeller and inter-stage stationary components; Step 2: Generate a computational grid for the geometric model; Step 3: Establish a dense phase carbon dioxide thermophysical property table, which is a data table for interpolating carbon dioxide temperature and static pressure based on the state equation and transmission characteristics; Step 4: Establishing a CFD model of each stage of a dense phase carbon dioxide centrifugal pump based on the computational grid and the dense phase carbon dioxide thermophysical property table; Step 5: Based on the CFD model, CFD iterative calculation is performed on the dense phase carbon dioxide centrifugal pump stage by stage, and flow field data of each stage of the multi-stage dense phase carbon dioxide centrifugal pump is output; Step 6: Change the parameter values ​​of the CFD model outlet boundary conditions and repeat step 5 to obtain the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions; Step 7: Extract the average flow parameters and thermal parameters of the inlet and outlet sections of each level from the flow field data of each level; Step 8: Calculate the performance parameters of each stage of the dense phase carbon dioxide centrifugal pump based on the average flow parameters and thermodynamic parameters of the inlet and outlet sections of each stage; Step 9: Calculate the performance parameters of the dense phase carbon dioxide centrifugal pump based on the energy parameters of each level; Step 10: Based on the flow field data of each stage of the dense phase carbon dioxide centrifugal pump under different working conditions obtained in step 6, steps 7 to 9 are repeated to obtain the overall performance parameters of the dense phase carbon dioxide centrifugal pump under different working conditions.

2. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 1 is characterized in that: Preferably, in step 1, Soildworks software is used to perform geometric modeling on each stage of the dense phase carbon dioxide centrifugal pump.

3. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 2 is characterized in that: In step 2, a computational mesh is generated for the geometric model using ANSYS-ICEM software.

4. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 3 is characterized in that: The computational domain of the geometric model is spatially discretized using an unstructured grid.

5. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 1, characterized in that: In the thermophysical properties table of dense phase carbon dioxide, the static pressure range is set to 6 to 25 MPa, the temperature range is 260 to 310 K, and the interpolation resolution is 100×100.

6. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 1, characterized in that: Step 4 includes, Step a1: importing the computational grid; Step a2: importing the dense phase carbon dioxide thermal property table; Step a3: Set the control equation to be solved; Step a4: Setting the turbulence model; Step a5: Set the numerical format of the convection term and diffusion term of the control equation; Step a6: Setting boundary conditions and dynamic and static interface processing methods; Step a7: Setting the pressure-velocity solution method; Step a8: Setting numerical iteration control parameters and target residual values; Step a9: Start iterative calculation until the equation residual reaches the set value.

7. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 6, characterized in that: The computational grid and the thermophysical property table of dense phase carbon dioxide were imported into the ANSYS-CFX software pre-processing. The control equation was the Reynolds-averaged Navier-Stokes equation. The turbulence model was SST k-ω to close the equation group. The numerical format of the convection term of the control equation was set to the second-order high-resolution upwind format discretization. The diffusion term was discretized using the second-order central format. The total temperature, total pressure and flow direction of the inlet boundary were set. The mass flow rate of the outlet boundary was set. The solid wall boundary was set to the adiabatic no-slip condition. The discrete pressure-velocity coupling solution method was set. The numerical iteration control parameter Courant number was equal to 50, and the target residual value was 1×10 -4 .

8. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 1, characterized in that: The mean flow parameters and thermodynamic parameters include mean static pressure, density, absolute velocity and stagnation enthalpy.

9. The method for numerical simulation analysis of internal flow of a dense phase carbon dioxide centrifugal pump according to claim 1, characterized in that: Performance parameters include polynomial index, power, head and efficiency.

10. The internal flow numerical simulation analysis method of a dense phase carbon dioxide centrifugal pump according to claim 9, characterized in that: The polynomial index expression is: Where p and ρ represent static pressure and density respectively; subscript i represents the i-th stage, in and out represent the average state parameters of the inlet and outlet sections of the stage respectively; The work expression is: Where V represents the absolute speed, The lift expression is: In the formula, g represents the acceleration due to gravity, The efficiency expression is: Where W tot Indicates the total power consumption, h st represents the stagnation enthalpy.

Images