Numerical simulation method for inlet adjustable guide vane of supercritical carbon dioxide compressor

Abstract

The invention discloses a numerical simulation method for an inlet adjustable guide vane of a supercritical carbon dioxide compressor, and relates to the field of supercritical carbon dioxide turbomachinery, and the method comprises the steps: S1, extracting a blade tip mean camber line of the inlet adjustable guide vane, and determining the gap distribution of the inlet adjustable guide vane; s2, carrying out grid division on a computational domain of the inlet adjustable guide vane to obtain a guide vane grid containing a part of gaps; s3, constructing a supercritical carbon dioxide physical property table through the supercritical carbon dioxide physical property equation, and embedding the table into a solver; and S4, simulation setting is completed for the solver, numerical simulation of the inlet adjustable guide vane of the supercritical carbon dioxide compressor is carried out, and the internal flow characteristic change rule of the inlet adjustable guide vane of the supercritical carbon dioxide compressor is obtained. By the adoption of the method, supercritical carbon dioxide inlet adjustable guide vane numerical simulation better fitting the actual situation can be achieved, and adverse effects caused by gaps are optimized while supercritical carbon dioxide flow characteristic changes caused by the gaps of the inlet guide vanes are considered.

Description

Technical Field

[0001] This invention belongs to the field of turbomachinery simulation, and in particular relates to a numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor. Background Technology

[0002] Supercritical carbon dioxide power systems possess advantages such as high cycle efficiency, wide heat source adaptability, and compact structure, making them suitable for the rapid and deep peak-shaving needs of power grids and a key development direction for future efficient and clean electricity. As a crucial component of this new power system, the supercritical carbon dioxide compressor consumes over 20% of the turbine's power generation efficiency, and its performance and operational stability directly affect the long-term service quality and cycle life of the entire cycle system. Therefore, while fully utilizing the special properties of the working fluid to improve the impeller's mechanical performance, it is necessary to establish a sound and complete control system for the supercritical carbon dioxide compressor unit.

[0003] Current research has clearly demonstrated that the inlet condition of a supercritical carbon dioxide compressor is a crucial factor affecting its operational performance, and adjustable inlet guide vanes have become an effective compressor control solution. On the one hand, they increase the design freedom of the impeller when the inlet is considered to be in a near-critical state of the working fluid; on the other hand, they can effectively regulate the condensation and evaporation rates within the channel, thereby reducing aerodynamic losses. Furthermore, the application of adjustable inlet guide vanes helps the compressor achieve maximum efficiency under different operating conditions. However, existing design methods fail to consider the coupling between the unique properties of supercritical carbon dioxide and the variable clearance of the guide vanes, and no method has been proposed to optimize the configuration of the adjustable inlet guide vane clearance of a supercritical carbon dioxide compressor. A more comprehensive explanation of numerical simulation methods in this area is needed.

[0004] Therefore, the existing numerical simulation methods for adjustable guide vanes at the inlet of supercritical carbon dioxide compressors suffer from low accuracy. Summary of the Invention

[0005] The purpose of this invention is to address the low accuracy problem of existing numerical simulation methods for adjustable guide vanes at the inlet of supercritical carbon dioxide compressors. A numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor is provided, comprising:

[0006] S1: Obtain the geometric model of the supercritical carbon dioxide compressor; extract the mid-arc line of the adjustable guide vane tip and the casing line from the geometric model of the supercritical carbon dioxide compressor inlet.

[0007] The intermediate arc line is rotated to its maximum angle to obtain a rotated intermediate arc line. This rotated intermediate arc line is then compared with the casing line of a supercritical carbon dioxide compressor.

[0008] The adjustable guide vane clearance distribution is obtained;

[0009] The mid-curve is defined as a point on the mid-curve that is equidistant from the suction and pressure surfaces of the blade along the local normal direction. The distance between the suction and pressure surfaces is equal to the blade thickness.

[0010] S2: Based on the inlet adjustable guide vane clearance distribution obtained in S1, the computational domain of the inlet adjustable guide vane is meshed to obtain a computational domain mesh with N pre-rotation angles; and the computational domain mesh with N pre-rotation angles is imported into the solver;

[0011] S3: Construct 14 sets of supercritical carbon dioxide property tables using the supercritical carbon dioxide property equations, and embed the 14 sets of supercritical carbon dioxide property tables into the solver.

[0012] S4: Perform simulation settings in the solver to obtain the configured solver. Then, conduct numerical simulations of the adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor within the configured solver to obtain the variation law of the flow characteristics of the adjustable guide vanes at the inlet of the supercritical carbon dioxide compressor.

[0013] Further, in step S1, a geometric model of a supercritical carbon dioxide compressor is obtained; the mid-arc line of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is extracted from the geometric model; the mid-arc line is rotated at its maximum angle to obtain the rotated mid-arc line; the distribution of the adjustable guide vane clearance is obtained by comparing the rotated mid-arc line with the casing line of the supercritical carbon dioxide compressor; the specific process is as follows:

[0014] S1.1 Obtain the geometric model of the supercritical carbon dioxide compressor; extract the mid-arc line of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor from the geometric model of the supercritical carbon dioxide compressor;

[0015] S1.2: Perform maximum angle rotation on the middle arc to obtain the rotated middle arc;

[0016] S1.3: Based on the comparison between the intermediate arc line after rotation processing and the casing line of a supercritical carbon dioxide compressor, the inlet adjustable guide vane clearance distribution is obtained.

[0017] Furthermore, in step S2, the computational domain of the adjustable guide vane is meshed based on the clearance distribution of the adjustable guide vane obtained in step S1, resulting in a computational domain mesh with N pre-rotation angles; and the computational domain mesh with N pre-rotation angles is imported into the solver; the specific process is as follows:

[0018] S2.1: Import the geometric model of the adjustable guide vane of the supercritical carbon dioxide compressor into NUMECA AutoGrid5 for gap mesh generation of the adjustable guide vane, and obtain the adjustable guide vane after gap mesh generation.

[0019] S2.2: Based on the gap meshing process, the computational domain mesh of N pre-rotation angles is obtained for the inlet adjustable guide vane, where N is a positive integer;

[0020] S2.3: Import the computational domain mesh with N pre-rotation angles into the solver NUMUCA FINE Turbo;

[0021] Further in S3, 14 sets of supercritical carbon dioxide property tables are constructed using the supercritical carbon dioxide property equation, and these 14 sets of supercritical carbon dioxide property tables are embedded into the solver; the specific process is as follows:

[0022] S3.1: Fourteen sets of supercritical carbon dioxide property tables were constructed using the SW-Crossover function equation for supercritical carbon dioxide.

[0023] S3.2: Use a Fortran program to convert the property values ​​of M supercritical carbon dioxide property tables into a coefficient matrix that the solver can recognize.

[0024] S3.3: Embed the 14 sets of supercritical carbon dioxide property tables stored in the form of coefficient matrices into the solver.

[0025] Further details regarding the variation of flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor in S4 include:

[0026] Conserved quantities in the flow field, viscous flux, inviscous flux and source term, phase change process in supercritical carbon dioxide flow, and eddy current characteristics inside supercritical carbon dioxide turbomachinery.

[0027] The simulation is set up in the solver to obtain a pre-configured solver. Numerical simulation of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is then performed within this pre-configured solver to obtain the variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor. The specific process is as follows:

[0028] S4.1: Perform simulation settings in the solver to obtain the configured solver; the specific process is as follows:

[0029] Set the inlet given total temperature and total pressure boundary conditions, set the outlet given static pressure or mass flow rate boundary conditions, and set the inlet adjustable guide vane speed to 0;

[0030] S4.2: Using the well-configured solver, solve the conserved quantities in the flow field using the steady-state Reynolds-averaged Navier-Stokes equations, including viscous flux, inviscous flux, and source terms;

[0031] S4.3: The phase transition process in the supercritical carbon dioxide flow process is simulated using a homogeneous conservation model in the configured solver.

[0032] S4.4: Using the SST model in the configured solver to simulate the internal eddy current characteristics of supercritical carbon dioxide turbomachinery;

[0033] The beneficial effects of this invention are as follows:

[0034] This invention enables a more realistic numerical simulation of adjustable guide vanes for supercritical carbon dioxide inlets. While considering the changes in supercritical carbon dioxide flow characteristics caused by the inlet guide vane clearance, it mitigates the adverse effects of the clearance. First, the invention extracts and rotates the mid-arc line at the tip of the adjustable guide vane. By comparing it with the casing line, the clearance distribution is obtained. Then, the constructed guide vane geometry is meshed, and a partial clearance technique is used to preserve the rotation axis, establishing mesh models of inlet guide vanes with different pre-rotation. Subsequently, the properties of supercritical carbon dioxide are embedded into the solver using bicubic interpolation, and the solver settings are completed, thereby obtaining the variation law of internal flow characteristics of the adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor. This invention provides technical support and guidance for the efficient design and stable operation of supercritical carbon dioxide compressor units and the entire power system under wide operating conditions. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the numerical simulation method for an adjustable guide vane at the inlet of a supercritical carbon dioxide compressor according to the present invention.

[0036] Figure 2 This is a schematic diagram illustrating the calculation of the arc of the adjustable guide vane at the inlet of a supercritical carbon dioxide compressor according to the present invention.

[0037] Figure 3 This is a schematic diagram illustrating the calculation of the adjustable guide vane clearance at the inlet of a supercritical carbon dioxide compressor according to the present invention.

[0038] Figure 4 This is a schematic diagram of an adjustable guide vane grid at the inlet of a supercritical carbon dioxide compressor according to the present invention;

[0039] Figure 5 This is a structural block diagram of a numerical simulation device for an adjustable guide vane at the inlet of a supercritical carbon dioxide compressor according to the present invention.

[0040] Figure 6 This is an internal structural diagram of a computer device according to the present invention;

[0041] Figure 7 This is a streamline diagram of the adjustable guide vane clearance at the inlet of a supercritical carbon dioxide compressor according to the present invention. Detailed Implementation

[0042] Specific implementation method one: Combining Figures 1-7 This invention is described.

[0043] S1: Obtain the geometric model of the supercritical carbon dioxide compressor; extract the mid-arc line of the adjustable guide vane tip and the casing line from the geometric model of the supercritical carbon dioxide compressor inlet.

[0044] The middle arc line is rotated at its maximum angle to obtain the rotated middle arc line. The rotated middle arc line is then compared with the casing line of the supercritical carbon dioxide compressor to obtain the inlet adjustable guide vane clearance distribution.

[0045] The mid-curve is defined as a point on the mid-curve that is equidistant from the suction and pressure surfaces of the blade along the local normal direction. The distance between the suction and pressure surfaces is equal to the blade thickness.

[0046] S2: Based on the inlet adjustable guide vane clearance distribution obtained in S1, the computational domain of the inlet adjustable guide vane is meshed to obtain a computational domain mesh with N pre-rotation angles; and the computational domain mesh with N pre-rotation angles is imported into the solver;

[0047] S3: Construct 14 sets of supercritical carbon dioxide property tables using the supercritical carbon dioxide property equations, and embed the 14 sets of supercritical carbon dioxide property tables into the solver.

[0048] S4: Perform simulation settings in the solver to obtain the set solver. Then, conduct numerical simulation of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor in the set solver to obtain the variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor.

[0049] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that...

[0050] In step S1, a geometric model of a supercritical carbon dioxide compressor is obtained. The mid-arc line of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is extracted from the geometric model. This mid-arc line is then rotated at its maximum angle to obtain a rotated mid-arc line. The rotated mid-arc line is then compared with the casing line of the supercritical carbon dioxide compressor to obtain the inlet adjustable guide vane clearance distribution. The specific process is as follows:

[0051] S1.1 Obtain the geometric model of the supercritical carbon dioxide compressor; extract the mid-arc coordinates of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor from the geometric model of the supercritical carbon dioxide compressor;

[0052] The geometric model of the supercritical carbon dioxide compressor can be obtained from the manufacturer or constructed by the experimenters based on the physical object.

[0053] S1.2: Perform maximum angle rotation processing on the mid-arc coordinates to obtain the rotated mid-arc coordinates;

[0054] S1.3: Extract the casing line coordinates of the supercritical carbon dioxide compressor from the geometric model of the supercritical carbon dioxide compressor;

[0055] The distribution of the inlet adjustable guide vane clearance is obtained by comparing the coordinates of the mid-arc line after rotation processing with the casing line coordinates of the supercritical carbon dioxide compressor.

[0056] The other steps and parameters are the same as in Specific Implementation Method 1.

[0057] Specific Implementation Method Three: The difference between this implementation method and Specific Implementation Methods One and Two is that...

[0058] In step S1.1, the mid-arc line of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is extracted from the geometric model of the supercritical carbon dioxide compressor; the specific process is as follows:

[0059] For specific calculation methods of the mid-arc line at the tip of the imported adjustable guide vane, please refer to the appendix. Figure 2 As shown,

[0060] S1.1.1: The initial position coordinates O of the intermediate arc are specified in the geometric model of the supercritical carbon dioxide compressor. n And the initial thickness line segment SS of the blade n -PS n ; among which SS n Indicates the initial coordinates of the suction surface; PS n Indicates the coordinates of the initial point of the pressure surface;

[0061] The initial position O of the middle arc line n and the initial thickness SS of the blade n -PS n ; This is for users in this field to configure themselves;

[0062] S1.1.2: Based on the initial position coordinates O of the middle arc. n And the initial thickness line segment SS of the blade n -PS n Extracting the coordinates of the mid-arc line from the geometric model of a supercritical carbon dioxide compressor; the specific process is as follows:

[0063] S1.1.2.1: Take SS on the suction surface of the blade n A little bit later SS n+1 PS on the pressure surface n A little bit of PS at the end n+1 And take the midpoint O of the line connecting the two points. n+1 The determination of the suction surface and pressure surface of the blade is well known to those skilled in the art;

[0064] S1.1.2.2: Determine line segment On -O n+1 With line segment SS n+1 -PS n+1 Is the included angle α between them equal to 90°?

[0065] If α equals 90°, then determine O. n+1 A point on the mid-arc line corresponds to a blade thickness of SS. n+1 -PS n+1 ,

[0066] If α is not equal to 90°, then continue searching for point PS on the pressure surface. n+1 Continue until the included angle α equals 90°, until a point on the middle arc is obtained.

[0067] S1.1.2.3: Repeat steps S1.1.2.1-S1.1.2.2 until the point on the pressure surface coincides with the point on the suction surface, thus obtaining half of the mid-arc coordinates; extract the other half of the mid-arc coordinates in reverse order, and finally extract the coordinates of the entire mid-arc.

[0068] The other steps and parameters are the same as in one of the specific implementation methods one or two.

[0069] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that...

[0070] In step S1.2, the middle arc is rotated at its maximum angle to obtain the rotated middle arc; the specific process is as follows:

[0071] The intermediate arc of the inlet adjustable guide vane is rotated by the maximum pre-rotation angle, which is 60° in this embodiment, to obtain the rotated intermediate arc. The coordinate transformation expression is:

[0072] x r =x i

[0073] y r =(z i -z0)sinθ+(y i -y0)cosθ+y0

[0074] z r =(z i -z0)cosθ-(y i -y0)sinθ+z0

[0075] Where, x r Let y be the spanwise coordinate of the blade after rotation. r Let z be the circumferential position coordinates of the blade after rotation. r Let x be the axial position coordinate of the blade after rotation. iLet y be the spanwise coordinate of the blade before rotation. i Let z be the circumferential position coordinates of the blade before rotation. i Let y0 and z0 be the axial position coordinates of the blade before rotation, and θ be the maximum pre-rotation angle.

[0076] The coordinates of the rotation axis position are the center coordinates of the middle arc.

[0077] The center coordinates of the arc are obtained from the arc coordinates extracted in S1.1.

[0078] The spanwise height of the mid-arc line, after being rotated at the maximum pre-spin angle, is compared with that of the casing line along the same axis. This ensures that the spanwise height of the casing line along the blade axis is slightly greater than that of the mid-arc line, thus preventing the blade from touching the casing while ensuring sufficient clearance. For details, please refer to the appendix. Figure 3 As shown,

[0079] The other steps and parameters are the same as those in one of the specific implementation methods one to three.

[0080] Specific Implementation Method Five: The difference between this implementation method and Specific Implementation Methods One to Four is that...

[0081] The specific process of obtaining the inlet adjustable guide vane clearance distribution in S1.3 by comparing the coordinates of the rotated arc line with the casing line coordinates of the supercritical carbon dioxide compressor is as follows:

[0082] S1.3.1: Calculate the spanwise height distribution of the rotated inlet adjustable guide vane based on the mid-arc line after rotation processing.

[0083] The spanwise height R of the rotated inlet adjustable guide vane blade This can be expressed as a formula:

[0084]

[0085] The formula for calculating the spanwise height distribution of the imported adjustable guide vanes is equivalent to R. blade With axial position z r The distribution of changes.

[0086] S1.3.2: Obtain the casing profile coordinates from the .geomturbo file of the supercritical carbon dioxide compressor geometric model. Perform fitting processing based on the casing profile coordinates to obtain the casing profile fitting function. Calculate the fitted spanwise height R of the casing based on the casing profile fitting function. shroud This can be expressed as a formula:

[0087] R shroud =f(z)

[0088] In the formula, f() represents the fitted curve, and z represents the axial position coordinates of the blade.

[0089] S1.3.3: Based on the spanwise height distribution of the rotated inlet adjustable guide vanes and the fitted spanwise height R of the casing. shroud The inlet adjustable guide vane clearance distribution was calculated;

[0090] The tip clearance (tip) of the imported adjustable guide vane is calculated using the following formula:

[0091] tip=(R shroud -R blade cosβ

[0092] Where β is the expansion angle of the casing profile;

[0093] β is a given value, and R changes. blade The final result is R that satisfies the clearance requirement. blade Distribution as a function of axial position z.

[0094] A positive tip clearance indicates that there is still room for clearance, while a negative tip clearance indicates that the blade is touching the casing, which can cause the blade to jam and should be avoided. To ensure that the adjustable guide vanes at the inlet of the supercritical carbon dioxide compressor can rotate unimpeded within a specified angle range, the tip clearance is maintained at 0.5 mm along the blade axis at all times to optimize the tip clearance configuration and avoid serious leakage flow losses; other steps and parameters are the same as in one of the specific implementation methods one to four.

[0095] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that...

[0096] In step S2, the computational domain of the adjustable guide vane is meshed based on the clearance distribution of the adjustable guide vane obtained in step S1, resulting in a computational domain mesh with N pre-rotation angles; and the computational domain mesh with N pre-rotation angles is imported into the solver; the specific process is as follows:

[0097] S2.1: Import the geometric model of the adjustable guide vane of the supercritical carbon dioxide compressor into NUMECA AutoGrid5 for gap mesh generation of the adjustable guide vane, and obtain the adjustable guide vane after gap mesh generation.

[0098] S2.2: Based on the gap meshing process, the computational domain mesh of N pre-rotation angles is obtained for the inlet adjustable guide vane, where N is a positive integer;

[0099] S2.3: Import the computational domain mesh with N pre-rotation angles into the solver.

[0100] The solver is the NUMUCA FINE Turbo solver;

[0101] NUMECAFINE Turbo is a highly efficient solver specifically designed for computational fluid dynamics (CFD), primarily used to analyze and optimize the flow characteristics of rotating machinery (such as turbines, compressors, etc.); other steps and parameters are the same as in one of the specific implementation methods one to five.

[0102] Specific Implementation Method Seven: The difference between this implementation method and Specific Implementation Methods One through Six is ​​that...

[0103] In step S2.1, the geometric model of the adjustable guide vane of the supercritical carbon dioxide compressor is imported into NUMECAAutoGrid5 for gap mesh generation processing of the adjustable guide vane, resulting in the adjustable guide vane after gap mesh generation processing.

[0104] The specific process is:

[0105] S2.1.1: Import the geometric model of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor into NUMECA AutoGrid5.

[0106] In NUMECA AutoGrid5 software, the O4H topology function is used to perform structured mesh generation on the blades, resulting in the structured mesh guide vanes.

[0107] S2.1.2: Apply the Partial Gap Properties function to import the inlet adjustable guide vane gap distribution obtained in S1 into the structured meshed guide vane; this yields the inlet adjustable guide vane after gap mesh processing; thus realizing the gap mesh generation of the inlet adjustable guide vane. See Appendix. Figure 4 shown

[0108] In this design, the central axis of the solid domain without gap treatment is used as the rotation axis of the guide vane. The solid domain refers to the physical part of the guide vane, that is, the physical shape of the guide vane, which is known to those skilled in the art.

[0109] The specific process in S2.2 for obtaining the computational domain grid of N pre-rotation angles based on the gap grid division of the inlet adjustable guide vane is as follows:

[0110] Set the pre-rotation starting angle and N rotation angles to obtain N pre-rotation angles; apply the Blade Expansion-Apply a rotation function in NUMECA AutoGrid5 to perform inlet guide vane pre-rotation processing and obtain the computational domain grid of N pre-rotation angles;

[0111] In one embodiment of the present invention, the inlet adjustable guide vane is rotated around the axis at -20°, 0°, 20°, 40° and 60° respectively, starting from 0° pre-rotation. The inlet adjustable guide vane of the supercritical carbon dioxide compressor with different pre-rotation angles is divided into the above grid as described above. The pre-rotation starting angle is 0°; and a computational domain grid of 5 pre-rotation angles is obtained.

[0112] The other steps and parameters are the same as those in any of the specific implementation methods one to six.

[0113] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that...

[0114] In step S3, 14 sets of supercritical carbon dioxide property tables are constructed using the supercritical carbon dioxide property equation, and these 14 sets of supercritical carbon dioxide property tables are embedded into the solver; the specific process is as follows:

[0115] S3.1: Fourteen sets of supercritical carbon dioxide property tables were constructed using the SW-Crossover function equation for supercritical carbon dioxide.

[0116] The specific process of constructing 14 sets of supercritical carbon dioxide property tables using the SW-Crossover function equation for supercritical carbon dioxide is well known to those skilled in the art.

[0117] S3.2: Use the Fortran program to convert the property value matrix in the 14 sets of supercritical carbon dioxide property tables into the coefficient matrix form. The coefficient matrix form is recognizable by the solver.

[0118] S3.3: Embed the 14 sets of supercritical carbon dioxide property tables stored in the form of coefficient matrices into the solver.

[0119] The other steps and parameters are the same as those in any of the specific implementation methods one to seven.

[0120] Specific Implementation Method Nine: The difference between this implementation method and Specific Implementation Methods One through Eight is that...

[0121] The 14 sets of supercritical carbon dioxide property tables in S3.1 include: (density-internal energy-dryness fraction) table, (density-internal energy-isobaric specific heat capacity) table, (density-internal energy-velocity of sound) table, (density-internal energy-thermal conductivity) table, (density-internal energy-dynamic viscosity) table, (density-internal energy-pressure) table, (density-internal energy-temperature) table, (temperature-pressure-density) table, (temperature-pressure-internal energy) table, (pressure-enthalpy-density) table, (pressure-enthalpy-entropy) table, (pressure-enthalpy-temperature) table, (pressure-entropy-enthalpy) table, and saturation line table.

[0122] Each of the 14 sets of supercritical carbon dioxide property tables includes M property value matrices; M is a positive integer.

[0123] Each set of tables contains many property value matrices, but the 14 sets of supercritical carbon dioxide property tables have the same number of property value matrices. It is necessary to implement the conversion between coefficient matrices and property value matrices one by one; to convert a table full of property value matrices into a table full of coefficient matrices.

[0124] In each set of tables, the first quantity in parentheses is the first independent variable, the second quantity is the second independent variable, and the third quantity is the dependent variable. Therefore, by inputting the independent variables into the functional equation to obtain the corresponding dependent variables, the property tables for supercritical carbon dioxide can be constructed. A property table is a data table used to record and display the changes in the physical properties (physical properties) of a substance with conditions such as temperature and pressure. Such tables are commonly used in engineering, scientific research, and industrial applications to help users quickly find and use the physical parameters of a substance under different conditions.

[0125] In section S3.2, the property value matrix in the 14 sets of supercritical carbon dioxide property tables is converted into a coefficient matrix using a Fortran program. The specific process is as follows:

[0126] S3.2.1: Using a bicubic table interpolation algorithm, the physical property matrix in the following tables is sequentially converted into a coefficient matrix form recognizable by the solver: (density-internal energy-dryness fraction), (density-internal energy-isobaric specific heat capacity), (density-internal energy-velocity of sound), (density-internal energy-thermal conductivity), (density-internal energy-dynamic viscosity), (density-internal energy-pressure), (density-internal energy-temperature), (temperature-pressure-density), (temperature-pressure-internal energy), (pressure-enthalpy-density), (pressure-enthalpy-entropy), (pressure-enthalpy-temperature), and (pressure-entropy-enthalpy). This matrix is ​​then written to the corresponding .atab format file and stored in the computer system. Each coefficient matrix contains 4×4 elements.

[0127] Convert a property value matrix in the j-th set of tables into a coefficient matrix format, expressed by the formula:

[0128]

[0129] in, j a Matrix Let P be the coefficient matrix in the j-th set of tables after transformation. Matrix For the parameter matrix, j A Matrix Let be a matrix of physical property values ​​in the j-th set of tables, and its expression is:

[0130]

[0131] in,j A( j x0, j y0), ... j A( j x3, j y3) is the property value of a reference node in a property value matrix in the j-th supercritical carbon dioxide property table; the reference node is a point in the table that is set manually; the setting method during the experiment can be determined by arranging the range and interval of the independent variables and uniformly distributing them. j x0, j x1, j x2, j x3∈ j x; j y0, j y1, j y2, j y3∈ j y; j x represents the property value of the first independent variable in a property value matrix in the j-th supercritical carbon dioxide property table; j y represents the property value of the second independent variable in a property value matrix of the j-th supercritical carbon dioxide property table;

[0132] Using the above formula, only 16 values ​​need to be selected for an independent variable to be calculated.

[0133] S3.2.2: Convert a property value matrix in the saturation line table into a coefficient matrix that the solver can recognize, expressed by the formula:

[0134]

[0135] Where, a′ Matrix This represents the coefficient matrix of the transformed saturation line table. Since the coefficient matrix after the transformation of the saturation line table is in one-dimensional format, each coefficient matrix contains 4 elements: A′(x′0), A′(x1′), ..., A′(x3′), which are the physical property values ​​of a reference node in a certain physical property value matrix in the saturation line table; the reference node is a point in the table that is manually set.

[0136] The other steps and parameters are the same as those in one of the specific implementation methods one to eight.

[0137] Specific Implementation Method Ten: The difference between this implementation method and Specific Implementation Methods One through Nine is that...

[0138] The variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor in S4 includes:

[0139] Conserved quantities in the flow field, viscous flux, inviscous flux and source term, phase change process in supercritical carbon dioxide flow, and eddy current characteristics inside supercritical carbon dioxide turbomachinery.

[0140] The simulation is set up in the solver to obtain a pre-configured solver. Numerical simulation of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is then performed within this pre-configured solver to obtain the variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor. The specific process is as follows:

[0141] S4.1: Perform simulation settings in the solver to obtain the configured solver; the specific process is as follows:

[0142] Set the inlet given total temperature and total pressure boundary conditions, set the outlet given static pressure or mass flow rate boundary conditions, and set the inlet adjustable guide vane speed to 0;

[0143] S4.2: Using the well-configured solver, solve for the conserved quantities in the flow field using the steady-state Reynolds-averaged Navier-Stokes equations, including viscous flux, inviscous flux, and source terms; the specific process is as follows:

[0144] Specifically, the Reynolds-averaged Navier-Stokes equations are:

[0145]

[0146] Where t is time, Ω is volume, S is area, and U is a conserved quantity. For inviscid vector flux, For viscous vector flux, S T For source terms.

[0147] S4.3: The homogeneous conservation model is used in the configured solver to simulate the phase transition process in the flow of supercritical carbon dioxide. Based on the thermodynamic equilibrium theory, the homogeneous conservation model assumes that the condensation phase transition occurs immediately, therefore the two phases are always in phase equilibrium. The thermophysical properties of supercritical carbon dioxide are related to the dryness fraction χ of the mixing term, expressed as:

[0148]

[0149] Where, ρ m ρ is the density of the mixed phase. l To correspond to the density of the saturated liquid phase, ρ g This corresponds to the density of the saturated gas phase.

[0150] The mixed-phase thermophysical parameters are calculated as follows:

[0151] A m =χA g +(1-χ)A l

[0152]

[0153] Among them, A m For mixed-phase thermophysical properties other than sound velocity (such as thermal conductivity, isobaric specific heat capacity, etc.), c m The velocity of sound is the mixed phase, p is the pressure, and c is the velocity of sound. g To correspond to the saturated gas phase sound velocity, c l This corresponds to the sound velocity in a saturated liquid phase.

[0154] S4.4: Using the SST model in the configured solver to simulate the internal eddy current characteristics of supercritical carbon dioxide turbomachinery;

[0155] Specifically, the SST extended wall function turbulence model is adopted to ensure that the numerical simulation results y+ meet engineering requirements. Furthermore, during the solver setup, total temperature and total pressure boundary conditions are given at the inlet, and static pressure or mass flow rate boundary conditions are given at the outlet. The rotational speed is specified as 0 for the adjustable guide vane at the inlet. The numerical simulation is considered convergent when the computational residual decreases by three orders of magnitude or less, the inlet and outlet flow rate deviation is less than 0.5%, and all physical quantities remain basically stable.

[0156] The other steps and parameters are the same as those in any of the specific implementation methods one to nine.

[0157] For detailed implementation method eleven, please refer to the appendix. Figure 5 As shown, a numerical simulation device for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor is provided, comprising: a gap processing module, a mesh generation module, a property processing module, and a simulation calculation module, wherein:

[0158] The gap processing module is used to extract the mid-arc line of the tip of the adjustable guide vane, perform maximum angle rotation processing on the mid-arc line, and determine the gap distribution of the adjustable guide vane by comparing it with the casing line.

[0159] The mesh generation module is used to mesh the computational domain of the inlet adjustable guide vane, obtain the guide vane mesh containing partial gaps, and import the mesh into the solver;

[0160] The property processing module is used to construct a supercritical carbon dioxide property table based on the supercritical carbon dioxide property equation and embed the table into the solver.

[0161] The simulation calculation module is used to complete the simulation settings of the solver, carry out numerical simulation of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor, and obtain the variation law of its internal flow characteristics.

[0162] Specific limitations regarding the numerical simulation device for the adjustable guide vane at the inlet of a supercritical carbon dioxide compressor can be found in the limitations of the numerical simulation method for the adjustable guide vane at the inlet of a supercritical carbon dioxide compressor mentioned above, and will not be repeated here. Each module in the aforementioned numerical simulation device for the adjustable guide vane at the inlet of a supercritical carbon dioxide compressor can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0163] Specific implementation twelve provides a computer device, which may be a server; its internal structure is shown in the appendix. Figure 6 As shown, the computer device includes a processor, memory, database, and network interface connected via a bus. The processor provides computational and control capabilities, while the memory includes non-volatile storage media and internal memory. The non-volatile storage media contains the operating system, computer programs, and the database. The internal memory provides the environment for the operation of the operating system and computer programs in the non-volatile storage media. The database stores numerical simulation data of the adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor. The network interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a numerical simulation method for the adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor.

[0164] See appendix Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the computer device to which the present invention is applied. A specific computer device may include more or fewer components, or combine certain components, or have different component arrangements.

[0165] Specific embodiment thirteen provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor, as described in any of the above embodiments.

[0166] The specific process of applying the method provided in the embodiments of the present invention is as follows:

[0167] The tip arc of the adjustable guide vane at the inlet of a supercritical carbon dioxide compressor was extracted. By rotating to the maximum pre-spin angle and comparing it with the casing line, the optimal tip clearance structure was determined. The processed geometry of the adjustable guide vane was then meshed. Partial tip clearance and blade rotation functions were used to achieve guide vane meshing under different pre-spin angles. The adjustable guide vane mesh and supercritical carbon dioxide properties were imported into the solver. The supercritical carbon dioxide properties were interpolated using bicubic interpolation. After solving the solver settings, numerical simulations were conducted to obtain the variation law of internal flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor.

[0168] Simulation analysis based on specific implementation methods one through ten

[0169] The flow characteristics within the adjustable guide vane clearance at the inlet of a supercritical carbon dioxide compressor can be found in the attached document. Figure 7 As shown, the inlet total temperature and total pressure are given as 307.1 K and 7.64 MPa, respectively, and the outlet flow rate boundary condition is given as 8.5 kg / s. As the tip clearance first contracts and then expands along the flow channel, supercritical carbon dioxide also exhibits flow changes such as local acceleration, diversion, and local deceleration during the flow process, which better matches the actual flow characteristics inside the adjustable guide vane at the inlet.

[0170] The above description is merely of preferred embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention, and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor, characterized in that, include: S1: Obtain the geometric model of the supercritical carbon dioxide compressor; extract the mid-arc line of the adjustable guide vane tip and the casing line from the geometric model of the supercritical carbon dioxide compressor inlet. The middle arc line is rotated at its maximum angle to obtain the rotated middle arc line. The rotated middle arc line is then compared with the casing line of the supercritical carbon dioxide compressor to obtain the inlet adjustable guide vane clearance distribution. S2: Based on the inlet adjustable guide vane clearance distribution obtained in S1, the computational domain of the inlet adjustable guide vane is meshed to obtain a computational domain mesh with N pre-rotation angles; and the computational domain mesh with N pre-rotation angles is imported into the solver; N is a positive integer; S3: Construct 14 sets of supercritical carbon dioxide property tables using the supercritical carbon dioxide property equation, and then embed the 14 sets of supercritical carbon dioxide property tables into the solver. S4: Perform simulation settings in the solver to obtain the set solver. Then, conduct numerical simulation of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor in the set solver to obtain the variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor.

2. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 1, characterized in that, In step S1, a geometric model of a supercritical carbon dioxide compressor is obtained. Within this model, the mid-arc line of the adjustable guide vane tip and the casing line are extracted. The mid-arc line is then rotated at its maximum angle to obtain a rotated mid-arc line. This rotated mid-arc line is then compared with the casing line of the supercritical carbon dioxide compressor to obtain the distribution of the adjustable guide vane clearance. The specific process is as follows: S1.1 Obtain the geometric model of the supercritical carbon dioxide compressor; extract the mid-arc coordinates of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor from the geometric model of the supercritical carbon dioxide compressor; S1.2: Perform maximum angle rotation processing on the mid-arc coordinates to obtain the rotated mid-arc coordinates; S1.3: Extract the casing line coordinates of the supercritical carbon dioxide compressor from the geometric model of the supercritical carbon dioxide compressor; The distribution of the inlet adjustable guide vane clearance is obtained by comparing the coordinates of the mid-arc line after rotation processing with the coordinates of the casing line of the supercritical carbon dioxide compressor.

3. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 2, characterized in that, In step S1.1, the mid-arc line of the tip of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is extracted from the geometric model of the supercritical carbon dioxide compressor; the specific process is as follows: S1.1.1: The initial position coordinates O of the intermediate arc are specified in the geometric model of the supercritical carbon dioxide compressor. n And the initial thickness line segment SS of the blade n -PS n ; among which SS n Indicates the initial coordinates of the suction surface; PS n Indicates the coordinates of the initial point of the pressure surface; S1.1.2: Based on the initial position coordinates O of the middle arc. n And the initial thickness line segment SS of the blade n -PS n The coordinates of the mid-arc line are extracted from the geometric model of the supercritical carbon dioxide compressor.

4. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 3, characterized in that, In step S1.2, the middle arc is rotated at its maximum angle to obtain the rotated middle arc; the specific process is as follows: The intermediate arc of the inlet adjustable guide vane is rotated by the maximum pre-rotation angle to obtain the rotated intermediate arc. The coordinate transformation expression for the rotation process is: x r =x i y r =(z i -z0)sinθ+(y i -y0)cosθ+y0 z r =(z i -z0)cosθ-(y i -y0)sinθ+z0 Where, x r Let y be the spanwise coordinate of the blade after rotation. r Let z be the circumferential position coordinates of the blade after rotation. r Let x be the axial position coordinate of the blade after rotation. i Let y be the spanwise coordinate of the blade before rotation. i Let z be the circumferential position coordinates of the blade before rotation. i Let y0 and z0 be the axial position coordinates of the blade before rotation, and θ be the maximum pre-rotation angle. The coordinates of the rotation axis position are the center coordinates of the middle arc. The center coordinates of the middle arc are obtained from the middle arc coordinates extracted in S1.

1.

5. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 4, characterized in that, The specific process of obtaining the inlet adjustable guide vane clearance distribution in S1.3 by comparing the coordinates of the rotated arc line with the casing line coordinates of the supercritical carbon dioxide compressor is as follows: S1.3.1: Calculate the spanwise height distribution of the rotated inlet adjustable guide vane based on the mid-arc line after rotation processing. The spanwise height R of the rotated inlet adjustable guide vane blade This can be expressed as a formula: S1.3.2: Obtain the casing profile coordinates from the geometric model of the supercritical carbon dioxide compressor. Perform fitting processing on the casing profile coordinates to obtain the casing profile fitting function. Calculate the fitted spanwise height R of the casing based on the casing profile fitting function. shroud This can be expressed as a formula: R shroud =f(z) In the formula, f() represents the fitted curve, and z represents the axial position coordinates of the blade. S1.3.3: Based on the spanwise height distribution of the rotated inlet adjustable guide vanes and the fitted spanwise height R of the casing. shroud The inlet adjustable guide vane clearance distribution was calculated; The tip clearance (tip) of the imported adjustable guide vane is calculated using the following formula: tip=(R shroud -R blade )cosβ Where β is the expansion angle of the casing profile.

6. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 5, characterized in that, In step S2, the computational domain of the adjustable guide vane is meshed based on the clearance distribution of the adjustable guide vane obtained in step S1, resulting in a computational domain mesh with N pre-rotation angles; and the computational domain mesh with N pre-rotation angles is imported into the solver; the specific process is as follows: S2.1: Import the geometric model of the adjustable guide vane of the supercritical carbon dioxide compressor into NUMECA AutoGrid5 for gap mesh generation of the adjustable guide vane, and obtain the adjustable guide vane after gap mesh generation. S2.2: Based on the gap meshing process, the computational domain mesh of N pre-rotation angles is obtained for the inlet adjustable guide vane, where N is a positive integer; S2.3: Import the computational domain mesh with N pre-rotation angles into the solver. The solver is the NUMUCA FINE Turbo solver.

7. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 6, characterized in that, In step S2.1, the geometric model of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is imported into NUMECAAutoGrid5 for gap mesh generation processing of the adjustable guide vane, resulting in the adjustable guide vane after gap mesh generation; the specific process is as follows: S2.1.1: Import the geometric model of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor into NUMECA AutoGrid5. In NUMECA AutoGrid5 software, the O4H topology function is used to perform structured mesh generation on the blades, resulting in guide vanes with structured mesh generation. S2.1.2: Apply the Partial Gap Properties function to import the inlet adjustable guide vane gap distribution obtained in S1 into the guide vane after structured mesh generation; obtain the inlet adjustable guide vane after gap mesh generation processing; In step S2.2, the computational domain grid with N pre-rotation angles is obtained from the inlet adjustable guide vane after the gap grid is processed. The specific process is as follows: Set the pre-rotation starting angle and N rotation angles to obtain N pre-rotation angles; apply the Blade Expansion-Apply a rotation function in NUMECA AutoGrid5 to perform inlet guide vane pre-rotation processing and obtain the computational domain grid of N pre-rotation angles.

8. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 7, characterized in that, In step S3, 14 sets of supercritical carbon dioxide property tables are constructed using the supercritical carbon dioxide property equation, and these 14 sets of supercritical carbon dioxide property tables are embedded into the solver; the specific process is as follows: S3.1: Fourteen sets of supercritical carbon dioxide property tables were constructed using the SW-Crossover function equation for supercritical carbon dioxide. S3.2: Use the Fortran program to convert the property value matrix in 14 sets of supercritical carbon dioxide property tables into coefficient matrix format. S3.3: Embed the 14 sets of supercritical carbon dioxide property tables stored in the form of coefficient matrices into the solver.

9. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 8, characterized in that, The 14 sets of supercritical carbon dioxide property tables in S3.1 include: (density-internal energy-dryness fraction) table, (density-internal energy-isobaric specific heat capacity) table, (density-internal energy-velocity of sound) table, (density-internal energy-thermal conductivity) table, (density-internal energy-dynamic viscosity) table, (density-internal energy-pressure) table, (density-internal energy-temperature) table, (temperature-pressure-density) table, (temperature-pressure-internal energy) table, (pressure-enthalpy-density) table, (pressure-enthalpy-entropy) table, (pressure-enthalpy-temperature) table, (pressure-entropy-enthalpy) table, and saturation line table. Each of the 14 sets of supercritical carbon dioxide property tables includes M property value matrices; M is a positive integer. In each set of tables, the first quantity in parentheses is the first independent variable, the second quantity is the second independent variable, and the third quantity is the dependent variable; In section S3.2, the property value matrix in the 14 sets of supercritical carbon dioxide property tables is converted into a coefficient matrix using a Fortran program. The specific process is as follows: S3.2.1: Using a bicubic table interpolation algorithm, the property matrix in the following tables is sequentially converted into a coefficient matrix form recognizable by the solver: (density-internal energy-dryness fraction), (density-internal energy-isobaric specific heat capacity), (density-internal energy-velocity of sound), (density-internal energy-thermal conductivity), (density-internal energy-dynamic viscosity), (density-internal energy-pressure), (density-internal energy-temperature), (temperature-pressure-density), (temperature-pressure-internal energy), (pressure-enthalpy-density), (pressure-enthalpy-entropy), (pressure-enthalpy-temperature), and (pressure-entropy-enthalpy). Specifically, the property matrix in the j-th set of tables is converted into a coefficient matrix form, expressed by the formula: in, j a Matrix Let P be the coefficient matrix in the j-th set of tables after transformation. Matrix For parameter matrices, j A Matrix Let be a matrix of physical property values ​​in the j-th set of tables, and its expression is: in, j A( j x0, j y0), ... j A( j x3, j y3) is the property value of a reference node in a property value matrix of the j-th supercritical carbon dioxide property table; the reference node is a point in the table that is set manually. j x0, j x1, j x2, j x3∈ j x; j y0, j y1, j y2, j y3∈ j y; j x represents the property value of the first independent variable in a property value matrix in the j-th supercritical carbon dioxide property table; j y represents the property value of the second independent variable in a property value matrix of the j-th supercritical carbon dioxide property table; S3.2.2: Convert a property value matrix in the saturation line table into a coefficient matrix that the solver can recognize, expressed by the formula: Where, a′ Matrix The coefficient matrix represents the transformed saturation line table. A′(x′0), A′(x1′), ... A′(x3′) are the property values ​​of a reference node in a property value matrix of a certain property value in the saturation line table; the reference node is a point in the table that is set manually.

10. The numerical simulation method for adjustable guide vanes at the inlet of a supercritical carbon dioxide compressor according to claim 9, characterized in that, The variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor in S4 includes: Conserved quantities in the flow field, viscous flux, inviscous flux and source term, phase change process in supercritical carbon dioxide flow, and eddy current characteristics inside supercritical carbon dioxide turbomachinery. The simulation is set up in the solver to obtain a pre-configured solver. Numerical simulation of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor is then performed within this pre-configured solver to obtain the variation law of the flow characteristics of the adjustable guide vane at the inlet of the supercritical carbon dioxide compressor. The specific process is as follows: S4.1: Perform simulation settings in the solver to obtain the configured solver; the specific process is as follows: Set the inlet given total temperature and total pressure boundary conditions, and the outlet given static pressure or mass flow rate boundary conditions in the solver. Set the inlet adjustable guide vane speed to 0; the solver is then set up. S4.2: Using the well-configured solver, solve the conserved quantities in the flow field using the steady-state Reynolds-averaged Navier-Stokes equations, including viscous flux, inviscous flux, and source terms; S4.3: The phase transition process in the supercritical carbon dioxide flow process is simulated using a homogeneous conservation model in the configured solver. S4.4: Using the SST model in the configured solver to simulate the internal vortex characteristics of supercritical carbon dioxide turbomachinery.

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