Micro-mixing single nozzle optimization method and system

Abstract

The invention discloses an optimization method and system for a micro-mixing single nozzle, and belongs to the technical field of combustor design. The method comprises the steps that the value range of design variables of the micro-mixing single nozzle is determined; sampling in the value range of each design variable to obtain parameter groups of a plurality of micro-mixing single nozzles, and constructing a corresponding micro-mixing single nozzle model according to each parameter group; performing finite element analysis on the different gridding micro-mixing single-nozzle three-dimensional models to obtain an optimal gridding micro-mixing single-nozzle three-dimensional model; gridding each micro-mixing single-nozzle model according to the grid parameters of the optimal gridding micro-mixing single-nozzle three-dimensional model, and respectively carrying out finite element analysis to obtain a uniformity index and a nozzle total pressure loss coefficient of each micro-mixing single-nozzle model; according to the method, the aims that the uniformity index is optimal and the total pressure loss coefficient of the nozzle reaches the threshold value are achieved, it can be ensured that the optimized micro-mixing single-nozzle model has the good mixing effect and meets the pressure loss requirement of the design standard, and the problem that the whole combustor is damaged after tempering occurs is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of burner design, and in particular to an optimization method and system for a micro-mixing single nozzle. Background Art

[0002] The micro-mixing single nozzle burner uses micro-tubes instead of the traditional single thick tube to organize combustion. Since the spatial size is significantly reduced, the degree of mixing between fuel and air is generally high. In the traditional design, the fuel and air are premixed at inlets in a single tube. This design often leads to a long premixing distance. In order to overcome this problem, the air pipe and the fuel pipe are coaxially sleeved so that the fuel injection direction is perpendicular to the oxidant flow direction, forming a cross-jet mixing. This method significantly shortens the premixing distance and improves the mixing efficiency. However, this also brings new challenges.

[0003] Since the diameter of the micro-mixing single nozzle is small and the fuel and air mixing area is close to the nozzle outlet, the flame can easily spread rapidly in the micro-tube. This rapid flame propagation not only accelerates the combustion process, but also may cause the micro-tube to be subjected to excessive heat load, thereby causing structural damage. The spread of flames may not only damage the entire micro-tube, but may also further affect the integrity of the nozzle or other key components. Such damage will not only lead to a decline in burner performance, but may also cause serious safety accidents such as fire or explosion.

[0004] The number, size, spacing and distance of air and fuel holes from the nozzle outlet are key factors affecting the uniformity and safety of fuel mixing. The selection of these parameters requires precise calculation and optimization to ensure effective mixing of fuel and air while avoiding premature flame spread in the micro-tube. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides an optimization method and system for a micro-mixing single nozzle, which uses a finite element analysis method to optimize the air holes and fuel holes of the micro-mixing single nozzle, solves the flashback problem of the micro-mixing single nozzle burner, and improves the safety of the entire burner.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for optimizing a micro-mixing single nozzle, comprising:

[0008] Step 1, determine the value range of the micro-mixing single nozzle design variables;

[0009] Step 2: sampling within the value range of each design variable to obtain multiple parameter groups of the micro-mixing single nozzle, and constructing a corresponding micro-mixing single nozzle model according to each parameter group;

[0010] Step 3, using different unstructured polyhedron grids to divide any micro-mixing single nozzle model, obtaining multiple gridded micro-mixing single nozzle three-dimensional models, performing finite element analysis on each gridded micro-mixing single nozzle three-dimensional model, and obtaining the optimal gridded micro-mixing single nozzle three-dimensional model;

[0011] Step 4, meshing each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and performing finite element analysis respectively to obtain the uniformity index and the nozzle total pressure loss coefficient of each micro-mixing single nozzle model;

[0012] Step 5, taking the uniformity index as the best and the nozzle total pressure loss coefficient reaching the threshold as the goal, obtain the optimal micro-mixing single nozzle model.

[0013] Preferably, the design variables of the micro-mixing single nozzle are structural parameters of the air pipe or the fuel pipe.

[0014] Preferably, the structural parameters of the air pipe include the inner diameter of the air pipe, the length, width, number and hole spacing of the air holes;

[0015] The structural parameters of the fuel pipe include the inner diameter of the fuel pipe, the number of fuel injection holes, the hole diameter and the hole spacing.

[0016] Preferably, the step of obtaining the optimal gridded micro-mixing single nozzle three-dimensional model comprises:

[0017] Different unstructured polyhedron grids are used to divide the same micro-mixing single nozzle model, and multiple different gridded micro-mixing single nozzle three-dimensional models are obtained.

[0018] The finite volume method is used to discretize the mass, momentum, energy and component control equations of the fluid, and the fluid flow model is set to adopt the Realizable k-ε Reynolds average model;

[0019] The total package reaction mechanism is used for simulation, and the pressure-velocity coupling of the fluid is used to determine the uniformity index of cold fuel and air, the velocity field distribution, and the nozzle inlet and outlet pressures;

[0020] The grid independence is verified according to the uniformity index, velocity field distribution and nozzle inlet and outlet pressure of each gridded micro-mixing single nozzle three-dimensional model, and the gridded micro-mixing single nozzle three-dimensional model is determined.

[0021] Preferably, the total package reaction mechanism is a methane / air one-step total package reaction mechanism, and the SIMPLEC algorithm is used to couple the pressure-velocity of the fluid.

[0022] Preferably, the expression of the uniformity index is as follows:

[0023]

[0024] Among them, Φ is the fuel mass fraction, v is the working fluid velocity, A is the area, and ρi is the material density.

[0025] Preferably, the calculation formula of the total pressure loss coefficient is as follows:

[0026]

[0027] Among them, Pin and Pout represent the total pressure at the burner inlet and outlet respectively.

[0028] An optimization system for a micro-mixing single nozzle, comprising:

[0029] A value module, used to determine the value range of the design variables of the micro-mixing single nozzle;

[0030] A model building module is used to sample within the value range of each design variable to obtain parameter groups of multiple micro-mixing single nozzles, and to build a corresponding micro-mixing single nozzle model according to each parameter group;

[0031] A mesh optimization module is used to divide any micro-mixing single nozzle model using different unstructured polyhedron meshes to obtain multiple meshed micro-mixing single nozzle three-dimensional models, perform finite element analysis on each meshed micro-mixing single nozzle three-dimensional model, and obtain the optimal meshed micro-mixing single nozzle three-dimensional model;

[0032] An analysis module is used to mesh each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and perform finite element analysis respectively to obtain the uniformity index and the total pressure loss coefficient of each micro-mixing single nozzle model;

[0033] The optimization module is used to obtain the optimal micro-mixing single nozzle model with the uniformity index being optimal and the total pressure loss coefficient of the nozzle reaching a threshold as the goal.

[0034] An electronic device, comprising:

[0035] Memory for storing computer programs;

[0036] A processor is used to implement the steps of the micro-mixing single nozzle optimization method when executing the computer program.

[0037] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the micro-mixing single nozzle optimization method.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] The present invention provides an optimization method for a micro-mixing single nozzle, which ensures the comprehensiveness and accuracy of the target hole optimization by setting multiple design variables and setting a reasonable value range for them. By sampling and combining these variables, a variety of possible micro-mixing single nozzle models can be constructed, providing a rich data basis for subsequent simulation analysis and optimization. The micro-mixing single nozzle model is divided by unstructured polyhedron grids. By comparing the calculation results under different grid amounts, the method can determine the optimal unstructured polyhedron grid, thereby ensuring the stability and reliability of the simulation results. This step is crucial to improving the accuracy and credibility of the simulation analysis. By introducing quantitative indicators such as uniformity index and total pressure loss coefficient, the method can objectively and accurately evaluate the performance of different micro-mixing single nozzle models. With the uniformity index being optimal and the nozzle total pressure loss coefficient reaching a threshold as the goal, it can be ensured that the optimized micro-mixing single nozzle model has both a good mixing effect and meets the pressure loss requirements of the design standard, avoiding the problem of damaging the entire burner after flashback occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 It is a structural schematic diagram of a micro-mixing single nozzle of the present invention;

[0042] Figure 2 It is the computational domain grid diagram of the micro-mixing single nozzle of the present invention;

[0043] Figure 3 This is a graph showing the change in uniformity index of the micro-mixing single nozzle of the present invention at different air inlet heights;

[0044] Figure 4 This is a graph showing the change in uniformity index of the micro-mixing single nozzle of the present invention at different air inlet widths;

[0045] Figure 5 This is a graph showing the change in uniformity index of the micro-mixing single nozzle of the present invention under different air pipe inner diameters;

[0046] Figure 6 This is a graph showing the change of nozzle pressure loss with the inner diameter of the air pipe for the micro-mixing single nozzle of the present invention;

[0047] Figure 7 is a structural diagram of the fuel pipe of the present invention;

[0048] Figure 8This is a graph showing the change in uniformity index under different numbers of fuel injection holes of the present invention;

[0049] Fig. 9 This is a graph showing the change in nozzle pressure loss with the number of fuel injection holes of the present invention;

[0050] Fig.10 This is a graph showing the change in uniformity index under different fuel injection hole diameters of the present invention;

[0051] Fig.11 This is a graph showing the change in nozzle pressure loss with the diameter of the fuel injection hole of the present invention;

[0052] Fig.12 It is a graph showing the variation of the uniformity index with the axial distance under different fuel injection hole spacings of the present invention;

[0053] Fig.13 The figure is a graph showing the variation of the total pressure loss coefficient of the nozzle according to the present invention with the distance between the fuel injection holes;

[0054] Fig.14 This is a graph showing the variation of the uniformity index with the axial distance under different fuel pipe diameters of the present invention;

[0055] Fig.15 The total pressure loss coefficient of the nozzle of the present invention varies with the fuel pipe diameter.

[0056] In the figure, 1, air pipe; 2, fuel pipe; 3, fuel perforation; 4, air hole; 5, annulus. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0058] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0059] See also Figure 1 , a micro-mixing single nozzle, comprising a fuel pipe 2 and an air pipe 1;

[0060] One end of the fuel pipe 2 is a fuel inlet, and the other end is closed. A plurality of fuel perforations 3 are arranged on the side wall, and the axial direction of the fuel perforations is perpendicular to the axis of the fuel pipe 2; an air hole 4 is arranged on the side wall of one end of the air pipe, and the other end is an ignition end; the fuel pipe is coaxially sleeved in the air pipe, the inlet end of the fuel pipe is sealed and connected to the end of the air pipe, and an annulus 5 for mixed gas is formed between the fuel pipes, the air hole is connected to the annulus, the oxidizing gas flows into the air pipe from the air hole and flows axially, the fuel injection direction is perpendicular to the air flow direction, and is mixed in the annulus area in the form of cross jets.

[0061] The micro-mixing single nozzle is composed of a fuel pipe and an air pipe arranged inside and outside, and an annular space for users to mix fuel and air is formed between the fuel pipe and the air pipe. The fuel gas is ejected from the fuel perforations opened downstream, and the air flows into the air pipe from the air holes. The fuel injection direction is perpendicular to the air flow direction, and the two are mixed in the form of cross jets, shortening the premixing distance of the fuel gas and air and improving the mixing uniformity.

[0062] In order to optimize the performance of the micro-mixing single nozzle, the present invention designs an optimization method for the micro-mixing single nozzle, comprising the following steps:

[0063] Step 1, determine the value range of the micro-mixing single nozzle design variables;

[0064] It should be noted that the design variables are the structural parameters of the micro-mixing single nozzle. The mixing uniformity of fuel and air and the total pressure loss coefficient are two important indicators for evaluating the performance of the micro-mixing single nozzle. The influencing factors of these two indicators are the structural parameters of the air pipe and the structural parameters of the fuel pipe. The structural parameters are taken as design variables, and a value range is set for each parameter, that is, the value range of the design variables.

[0065] Step 2: Sampling is performed within the value range of each design variable to obtain parameter groups of multiple micro-mixing single nozzles, and a corresponding micro-mixing single nozzle model is constructed according to each parameter group.

[0066] Step 3: Divide any micro-mixing single nozzle model using different unstructured polyhedron grids to obtain multiple gridded micro-mixing single nozzle three-dimensional models, perform finite element analysis on each gridded micro-mixing single nozzle three-dimensional model, and obtain the optimal gridded micro-mixing single nozzle three-dimensional model.

[0067] In this step, the main purpose is to obtain the optimal meshing parameters. Different unstructured polyhedron meshes are used, that is, different mesh parameters are used to mesh the same micro-hybrid single nozzle three-dimensional model separately, thereby forming multiple micro-hybrid single nozzle three-dimensional models with different mesh parameters. Finite element simulation is then performed on each model, and the optimal mesh parameters are determined based on the simulation results.

[0068] Step 4: mesh each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and perform finite element analysis on each micro-mixing single nozzle model to obtain the uniformity index and nozzle total pressure loss coefficient of each micro-mixing single nozzle model.

[0069] Step 5: With the uniformity index being optimal and the nozzle total pressure loss coefficient reaching a threshold as the goal, the optimal micro-mixing single nozzle model is obtained.

[0070] Example 1

[0071] The following takes the air pipe as an example to explain the above optimization method in detail.

[0072] See also Figure 2-6 , an optimization method for an air pipe of a micro-mixing single nozzle, comprising the following steps:

[0073] Step 1: Set the design variables of the air pipe and set the value range for each variable;

[0074] The design variables are the inner diameter of the air pipe, the length, width, number and hole spacing of the air holes. It should be noted that the outer diameter of the fuel pipe in the present application is a set value. The annular area of ​​the premixing section, that is, the width of the annular space, can be adjusted by changing the inner diameter of the air pipe. The length and width of the air holes determine the air intake flow rate and rate.

[0075] Step 2: Sampling is performed within the value range of each design variable to obtain parameter groups of multiple air pipes, and a corresponding micro-mixing single nozzle model is constructed according to each parameter group.

[0076] Step 3: Divide any micro-mixing single nozzle model using different unstructured polyhedron grids to obtain multiple gridded micro-mixing single nozzle three-dimensional models, perform finite element analysis on each gridded micro-mixing single nozzle three-dimensional model, and obtain the optimal gridded micro-mixing single nozzle three-dimensional model.

[0077] It should be noted that, during the optimization process of the air tube, the structural parameters of the combustion tube adopt set parameters.

[0078] The finite element analysis method of the gridded micro-mixing single nozzle three-dimensional model is as follows:

[0079] S3.1, using different unstructured polyhedral grids to divide the same micro-mixing single nozzle model, and obtain multiple different gridded micro-mixing single nozzle three-dimensional models, (see Figure 2 );

[0080] S3.2, import the gridded micro-mixing single nozzle 3D model into ANSYS FLUENT, use the finite volume method to discretize the mass, momentum, energy and component control equations of the fluid, and set the fluid flow model to adopt the Realizable k-ε Reynolds average model;

[0081] S3.3, the methane / air one-step total package reaction mechanism is used for simulation, and the SIMPLEC algorithm is used for the pressure-velocity coupling of the fluid to achieve better convergence. The momentum, energy, and components are all calculated with second-order accuracy to determine the uniformity index of cold fuel and air, the velocity field distribution, and the nozzle inlet and outlet pressures. The total pressure loss coefficient of the nozzle is calculated based on the nozzle inlet and outlet pressures.

[0082] S3.4, the uniformity index, nozzle outlet velocity distribution and centerline velocity distribution of each gridded micro-mixing single nozzle three-dimensional model are verified to be independent of the grid, and the optimal unstructured polyhedron grid is determined by comparing the calculation results under different grid amounts.

[0083] Step 4: mesh each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and perform finite element analysis on each micro-mixing single nozzle model to obtain the uniformity index and nozzle total pressure loss coefficient of each micro-mixing single nozzle model.

[0084] Finite element analysis was performed on each three-dimensional model using the selected unstructured polyhedron mesh parameters to obtain the uniformity index of each model under the optimal mesh and the total pressure loss coefficient of the nozzle.

[0085] The mixing uniformity of fuel and air and the burner pressure loss are two important indicators for evaluating the performance of micro-mixing single nozzles. The uniformity index is one of the standards for quantitatively measuring or evaluating the gas mixing effect, and the expression is as follows:

[0086] The expression of uniformity index is as follows:

[0087]

[0088] Among them, Φ is the fuel mass fraction, v is the working fluid velocity, A is the area, and ρi is the material density.

[0089] The calculation formula of the pressure loss is as follows:

[0090]

[0091] The calculation formula of total pressure loss coefficient is as follows:

[0092]

[0093] Among them, Pin and Pout represent the total pressure at the burner inlet and outlet respectively.

[0094] When the uniformity index is not less than 0.95, the fuel and air are mixed evenly; the design standard of the total pressure loss coefficient is set at less than 5%.

[0095] Step 5: With the uniformity index being optimal and the nozzle total pressure loss coefficient reaching a threshold as the goal, an optimal micro-mixing single nozzle model is obtained, and the structure of the air pipe is optimized according to the optimal micro-mixing single nozzle model, so that efficient mixing can be achieved within a short distance and the nozzle pressure loss meets the design standard.

[0096] The configuration of the air duct is studied by a three-dimensional numerical simulation method, and the micro-mixing single nozzle is optimized. The computational domain grid is as follows: Figure 2 As shown, the minimum grid size is 0.04 mm, the grid is verified to be independent, and the fuel and oxidant are methane and air respectively. In addition, the basic dimensions of the air inlet height, width and air tube inner diameter are 10 mm, 2 mm and 8 mm respectively.

[0097] The variation of uniformity index with axial distance at different air inlet heights is shown in the figure Figure 3 As shown in the figure, there are 3 curves corresponding to the results of air inlet heights of 5mm, 10mm and 15mm. As the axial distance increases, the nonlinear increase trend of the 3 curves is similar. However, compared with the curves of air inlet heights of 5mm and 15mm, the curve corresponding to the height of 10mm is the highest, and the fuel-air mixing effect is best under this condition.

[0098] Figure 4 As shown in the figure, the uniformity index changes with axial distance under different air inlet widths. The figure contains 3 curves, corresponding to the results of air inlet widths of 1mm, 2mm and 3mm. As the axial distance increases, the nonlinear increase trend of the three curves is similar. It can be clearly seen that under the condition of fixed axial height, when the air inlet width is 2mm, the uniformity index is significantly greater than the results of 1mm and 3mm, indicating that the fuel-air mixing effect is best under this condition.

[0099] Table 1 lists the total pressure loss coefficient of the nozzle at different air inlet heights and widths. It can be seen that the increase in air inlet height or width causes the nozzle pressure loss to decrease. In addition, when the air inlet height is 5mm or the width is 1mm, the total pressure loss coefficient is greater than 5%, which does not meet the design standards of this project.

[0100] According to the above results, the height and width of the air inlet in the micro-mixing burner of this project are preferably 10 mm and 2 mm respectively.

[0101] Table 1 Nozzle total pressure loss coefficient at different air inlet heights and widths

[0102]

[0103]

[0104] Figure 5 The figure shows the change of uniformity index with axial height under different air pipe diameter conditions. The figure contains 3 curves, corresponding to the results of air pipe diameters of 6mm, 8mm and 10mm. It can be seen that the change trends of the 3 curves are similar, but there is a certain difference in the values. Among them, under the condition of fixed axial height, when the air pipe diameter is 8mm, the uniformity index is the largest, which shows that the fuel-air mixing effect is best under this condition.

[0105] Figure 6 is the change of the total pressure loss coefficient of the nozzle with the air pipe diameter. As the air pipe diameter increases, the total pressure loss coefficient of the nozzle increases nonlinearly, and when the air pipe diameter is 6mm, 8mm and 10mm, the corresponding total pressure loss coefficient is 3.342%, 3.996% and 6.215% respectively.

[0106] In summary, when the air pipe diameter is 10mm, the total pressure loss coefficient is greater than 5%, which does not meet the design standards of this project, so the appropriate pipe diameter is selected between 6mm and 8mm. According to the uniformity index results, the air pipe diameter in the micro-mixing burner of this project is preferably 8mm.

[0107] The air hole optimization method of the present application allows the fuel to be vertically injected into the surrounding air under the optimal structure of the air hole, and the two are quickly and evenly mixed. By studying the influence of the air inlet height, width and air pipe inner diameter on the air flow mixing process and nozzle pressure loss, and optimizing the micro-mixing single nozzle configuration with excellent performance according to the data change law; under this configuration, once backfire occurs, the flame will be transmitted back into the nozzle, and the flame will be extinguished near the downstream injection hole of the fuel pipe, and will not enter the fuel pipe to cause greater damage.

[0108] Example 2

[0109] Figure 7 2 is a structural diagram of a fuel pipe. The above optimization method is described in detail below by taking the fuel pipe as an example.

[0110] See also Figure 8-15 , a method for optimizing a fuel pipe of a micro-mixing single nozzle comprises the following steps:

[0111] Step 1: Set the design variables of the fuel pipe and set the value range for each variable;

[0112] The design variables are the inner diameter of the fuel pipe, the number of fuel injection holes, the hole diameter and the hole spacing.

[0113] It should be noted that the configuration of the air pipe adopts the optimal configuration optimized in Example 1.

[0114] Step 2: Sampling is performed within the value range of each design variable to obtain parameter groups of multiple fuel pipes, and a corresponding micro-mixing single nozzle model is constructed according to each parameter group.

[0115] Step 3: Divide any micro-mixing single nozzle model using different unstructured polyhedron grids to obtain multiple gridded micro-mixing single nozzle three-dimensional models, perform finite element analysis on each gridded micro-mixing single nozzle three-dimensional model, and obtain the optimal gridded micro-mixing single nozzle three-dimensional model.

[0116] The finite element analysis method of the gridded micro-mixing single nozzle three-dimensional model is the same as that in Example 1.

[0117] Step 4: mesh each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and perform finite element analysis on each micro-mixing single nozzle model to obtain the uniformity index and nozzle total pressure loss coefficient of each micro-mixing single nozzle model.

[0118] Finite element analysis was performed on each three-dimensional model using the selected unstructured polyhedron mesh parameters to obtain the uniformity index of each model under the optimal mesh and the total pressure loss coefficient of the nozzle.

[0119] Step 5: With the uniformity index being optimal and the nozzle total pressure loss coefficient reaching a threshold as the goal, an optimal micro-mixing single nozzle model is obtained, and the structure of the fuel pipe is optimized according to the optimal micro-mixing single nozzle model, so that efficient mixing can be achieved within a short distance and the nozzle pressure loss meets the design standard.

[0120] A three-dimensional numerical simulation method is used to study the influence of the number and diameter of the fuel injection holes and the inner diameter of the fuel nozzle, and the micro-mixing single nozzle burner is optimized. The computational domain grid is as follows: Figure 2 As shown, the minimum grid size is 0.04mm, the grid is verified to be independent, and the fuel and oxidant are methane and air respectively. In addition, the basic dimensions of the number of fuel injection holes, hole diameter, hole spacing and the inner diameter of the fuel nozzle are 8, 0.8mm, 5mm and 2mm respectively. When the uniformity index is not less than 0.95, the fuel and air are mixed evenly; in addition, the design standard of the total pressure loss coefficient is set to less than 5% in this project.

[0121] Number of fuel injection holes

[0122] The nozzle pressure loss of a burner with good performance generally does not exceed 5%, and the uniformity index is generally greater than 0.95.

[0123] Figure 8The figure shows the variation of uniformity index with axial distance under different numbers of fuel injection holes. The figure contains 5 curves, corresponding to the number of holes of 4, 8, 12, 16 and 24. It can be seen from the figure that the uniformity index increases nonlinearly with the increase of axial distance under different numbers of holes, and the numerical difference is not large, indicating that the number of holes has little effect on the fuel-air mixing process.

[0124] The total pressure loss coefficient of the nozzle under different numbers of fuel injection holes is as follows Fig. 9 As shown, it can be seen that as the number of holes increases, the total pressure loss coefficient decreases nonlinearly, and when the number of holes is greater than 8, the decline rate decreases significantly. It can be seen from the figure that when the number of holes is 4, the corresponding nozzle total pressure loss coefficient is 6.217%, which exceeds the burner design standard of this project (<5%); when the number of holes increases to 8, the total pressure loss coefficient decreases to 4.456%, which is close to the design standard; when the number of holes is increased to 12, the total pressure loss coefficient decreases to 3.996%. On this basis, the total pressure loss coefficient decreases to 3.663% when the number of holes is increased to 24, which is not much different.

[0125] In summary, since the number of fuel injection holes has little effect on mixing uniformity, the optimal number of fuel injection holes for the micro-mixing burner in this project is 12 based on the total pressure loss coefficient of the nozzle.

[0126] Fuel injection hole diameter

[0127] Fig.10 The figure shows the change of uniformity index along axial distance under different fuel injection hole diameter conditions. The figure contains five kinds of apertures, namely 0.4mm, 0.6mm, 0.8mm, 1.0mm and 1.2mm. It can be seen that the change trend of uniformity index with axial distance under different apertures is basically the same, but there is a certain difference in value. As the axial height increases, the difference between the curves in the figure gradually decreases. When the axial height is greater than 120mm, the five curves converge together, and the corresponding uniformity index is greater than 0.95. In addition, it can be clearly seen from the figure that under a fixed axial height, when the aperture is 0.8mm, the uniformity index is the largest, and when the axial height is 80mm, the uniformity index is greater than 0.95, and the fuel-air mixing is best under this aperture.

[0128] The change of the total pressure loss coefficient of the nozzle under different fuel injection hole diameters is as follows Fig.11 As shown in the figure, the total pressure loss coefficient shows a nonlinear downward trend with the increase of the aperture, and when the aperture is greater than 0.6mm, the rate of decline decreases significantly, and the total pressure loss coefficient decreases from 4.6% at 0.6mm to about 3.8% at 1.2mm. Based on the above results, the uniformity index and the total pressure loss coefficient are comprehensively evaluated, and the preferred aperture of the fuel injection hole in the micro-mixed burner of this project is 0.8mm.

[0129] Effect of fuel injection hole spacing

[0130] The fuel injection hole spacing refers to the distance between the centers of two adjacent circular holes in the axial direction. Fig.12 The variation of uniformity index along axial distance under the conditions of fuel injection hole spacing of 2mm, 5mm, 7mm and 10mm is given. It can be seen that the uniformity index under different hole spacings increases nonlinearly with the increase of axial height. It can be clearly seen from the figure that compared with the results of hole spacing of 2mm, 7mm and 10mm, the uniformity index corresponding to the hole spacing of 5mm is the largest at any axial height, and when the axial height is 80mm, the uniformity index is greater than 0.95.

[0131] The total pressure loss coefficient of the nozzle under the above different hole spacings is given in Fig.13 It can be seen that as the hole spacing increases, the total pressure loss coefficient shows a slow downward trend, and the value changes slightly. When the hole spacing is 2mm, the total pressure loss coefficient is 4.129%, when the hole spacing increases to 5mm, the total pressure loss coefficient decreases to 3.996%, when the hole spacing is increased to 7mm, the total pressure loss coefficient increases slightly to 4.037%, and when the hole spacing is further increased to 10mm, the total pressure loss coefficient decreases to 3.869%.

[0132] In summary, since the fuel injection hole spacing has little effect on the total pressure loss coefficient of the nozzle, the fuel injection hole spacing in the micro-mixing burner of this project is preferably 5mm according to the uniformity index.

[0133] Effect of fuel nozzle inner diameter

[0134] Fig.14 The variation of uniformity index along axial distance under the conditions of fuel pipe diameters of 1.5mm, 2.0mm, 2.5mm and 3.0mm is given. It can be seen from the figure that the nonlinear increase trend of uniformity index with increasing axial height under different fuel pipe diameters is similar, but there are certain differences in values. Under the condition of fixed axial height, it is found that the uniformity index corresponding to the fuel pipe diameter of 2.0mm is the largest, and when the axial height is 80mm, the uniformity index is greater than 0.95.

[0135] Fig.15 The figure shows the change of the total pressure loss coefficient of the nozzle with the fuel pipe diameter. It can be seen that when the fuel pipe diameter increases from 1.5mm to 3.0mm, the total pressure loss coefficient decreases nonlinearly. When the fuel pipe diameter is greater than 2.0mm, the decrease rate decreases significantly, and the total pressure loss coefficient is less than 5%.

[0136] Taking into account the uniformity index and total pressure loss coefficient, the fuel pipe diameter in the micro-mixing burner of this project is preferably 2.0mm.

[0137] Correspondingly, the present application also provides an optimization system for a micro-mixing single nozzle, comprising:

[0138] A value module, used to determine the value range of the design variables of the micro-mixing single nozzle;

[0139] A model building module is used to sample within the value range of each design variable to obtain parameter groups of multiple micro-mixing single nozzles, and to build a corresponding micro-mixing single nozzle model according to each parameter group;

[0140] A mesh optimization module is used to divide any micro-mixing single nozzle model using different unstructured polyhedron meshes to obtain multiple meshed micro-mixing single nozzle three-dimensional models, perform finite element analysis on each meshed micro-mixing single nozzle three-dimensional model, and obtain the optimal meshed micro-mixing single nozzle three-dimensional model;

[0141] An analysis module is used to mesh each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and perform finite element analysis respectively to obtain the uniformity index and the total pressure loss coefficient of each micro-mixing single nozzle model;

[0142] The optimization module is used to obtain the optimal micro-mixing single nozzle model with the uniformity index being optimal and the total pressure loss coefficient of the nozzle reaching a threshold as the goal.

[0143] It should be noted that in the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of each module is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules can be combined or integrated into another device, or some features can be ignored or not executed. The module described as a separate component may or may not be physically separated. The component displayed as a module may be a physical unit or multiple physical units, that is, it may be located in one place, or it may be distributed in multiple different places. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment.

[0144] In addition, each module in each embodiment of the present invention may be integrated into a processing unit, each module may exist physically separately, or two or more modules may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0145] An electronic device provided in an embodiment of the present application includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the steps of a method for optimizing a micro-mixing single nozzle as described in any of the above embodiments are implemented.

[0146] Another electronic device provided in the embodiment of the present application may also include: an input port connected to the processor, used to transmit multimodal data collected by an external acquisition device to the processor; and a display unit connected to the processor, used to display the processing results of the processor to the outside world; a communication module connected to the processor, used to realize communication between the electronic device and the outside world. The display unit can be a display panel, a laser scanning display, etc.; the communication mode adopted by the communication module includes but is not limited to mobile high-definition link technology (HML), universal serial bus (USB), high-definition multimedia interface (HDMI), wireless connection (including wireless fidelity technology (WiFi), Bluetooth communication technology, low-power Bluetooth communication technology, and communication technology based on IEEE802.11s).

[0147] An embodiment of the present application provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the steps of a method for optimizing a micro-mixing single nozzle as described in any of the above embodiments are implemented.

[0148] The computer-readable storage medium involved in the present application includes random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the technical field.

[0149] For the description of the relevant parts of the air hole optimization system, electronic device and computer-readable storage medium of a micro-mixing single nozzle provided in the embodiment of the present application, please refer to the detailed description of the corresponding parts in the optimization method of a micro-mixing single nozzle provided in the embodiment of the present application, which will not be repeated here. In addition, the parts of the above technical solutions provided in the embodiment of the present application that are consistent with the implementation principles of the corresponding technical solutions in the prior art are not described in detail to avoid excessive elaboration.

[0150] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for optimizing a micro-mixing single nozzle, characterized in that: include: Step 1, determine the value range of the micro-mixing single nozzle design variables; Step 2: sampling within the value range of each design variable to obtain parameter groups of multiple micro-mixing single nozzles, and constructing a corresponding micro-mixing single nozzle model according to each parameter group; Step 3, using different unstructured polyhedron grids to divide any micro-mixing single nozzle model, obtaining multiple gridded micro-mixing single nozzle three-dimensional models, performing finite element analysis on each gridded micro-mixing single nozzle three-dimensional model, and obtaining the optimal gridded micro-mixing single nozzle three-dimensional model; Step 4, meshing each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and performing finite element analysis respectively to obtain the uniformity index and the nozzle total pressure loss coefficient of each micro-mixing single nozzle model; Step 5, taking the uniformity index as the best and the nozzle total pressure loss coefficient reaching the threshold as the goal, obtain the optimal micro-mixing single nozzle model.

2. The optimization method of a micro-mixing single nozzle according to claim 1, characterized in that: The design variables of the micro-mixing single nozzle are structural parameters of the air pipe or the fuel pipe.

3. The optimization method of a micro-mixing single nozzle according to claim 2, characterized in that: The structural parameters of the air pipe include the inner diameter of the air pipe, the length, width, number and hole spacing of the air holes; The structural parameters of the fuel pipe include the inner diameter of the fuel pipe, the number of fuel injection holes, the hole diameter and the hole spacing.

4. The optimization method of a micro-mixing single nozzle according to claim 1, characterized in that: The obtaining of the optimal gridded micro-mixing single nozzle three-dimensional model comprises: Different unstructured polyhedron grids are used to divide the same micro-mixing single nozzle model, and multiple different gridded micro-mixing single nozzle three-dimensional models are obtained. The finite volume method is used to discretize the mass, momentum, energy and component control equations of the fluid, and the fluid flow model is set to adopt the Realizable k-ε Reynolds average model; The total package reaction mechanism is used for simulation, and the pressure-velocity coupling of the fluid is used to determine the uniformity index of cold fuel and air, the velocity field distribution, and the nozzle inlet and outlet pressures; The grid independence is verified according to the uniformity index, velocity field distribution and nozzle inlet and outlet pressure of each gridded micro-mixing single nozzle three-dimensional model, and the gridded micro-mixing single nozzle three-dimensional model is determined.

5. The optimization method of a micro-mixing single nozzle according to claim 1, characterized in that: The overall reaction mechanism is a one-step overall reaction mechanism of methane / air, and the SIMPLEC algorithm is used to couple the pressure-velocity of the fluid.

6. The optimization method of a micro-mixing single nozzle according to claim 1, characterized in that: The expression of the uniformity index is as follows: Among them, Φ is the fuel mass fraction, v is the working fluid velocity, A is the area, and ρi is the material density.

7. The optimization method of a micro-mixing single nozzle according to claim 1, characterized in that: The calculation formula of the total pressure loss coefficient is as follows: Among them, Pin and Pout represent the total pressure at the burner inlet and outlet respectively.

8. An optimization system for a micro-mixing single nozzle, characterized in that: include: A value module, used to determine the value range of the design variables of the micro-mixing single nozzle; A model building module is used to sample within the value range of each design variable to obtain parameter groups of multiple micro-mixing single nozzles, and to build a corresponding micro-mixing single nozzle model according to each parameter group; A mesh optimization module is used to divide any micro-mixing single nozzle model using different unstructured polyhedron meshes to obtain multiple meshed micro-mixing single nozzle three-dimensional models, perform finite element analysis on each meshed micro-mixing single nozzle three-dimensional model, and obtain the optimal meshed micro-mixing single nozzle three-dimensional model; An analysis module is used to mesh each micro-mixing single nozzle model according to the mesh parameters of the optimal meshed micro-mixing single nozzle three-dimensional model, and perform finite element analysis respectively to obtain the uniformity index and the total pressure loss coefficient of each micro-mixing single nozzle model; The optimization module is used to obtain the optimal micro-mixing single nozzle model with the uniformity index being optimal and the total pressure loss coefficient of the nozzle reaching a threshold as the goal.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the micro-mixing single nozzle optimization method as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the optimization method of the micro-mixing single nozzle as described in any one of claims 1 to 7 are implemented.

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