Multi-branch nozzle flow coefficient prediction method, electronic equipment and medium

Abstract

The invention relates to a multi-branch nozzle flow coefficient prediction method, electronic equipment and a medium. The prediction method comprises the steps that flow coefficients of a single nozzle under different pressure conditions are quantified; on the basis of the quantized flow coefficient, flow coefficient correction is conducted on the single nozzle at different angles, so that an angle correction coefficient is calculated; fitting a pressure correction coefficient equation, and correcting the flow coefficient of the single nozzle according to different pressure differences to obtain a pressure correction coefficient; combining the flow coefficient, the pressure correction coefficient and the angle correction coefficient to obtain an improved single-nozzle flow coefficient; establishing a multi-branch nozzle model, and setting the number and arrangement form of nozzles according to actual requirements; and calculating the total flow coefficient of the multi-branch nozzles according to the improved flow coefficient of the single nozzle and the number of the nozzles. By means of the method, flow prediction of a single-nozzle system and a multi-nozzle system under different working conditions is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aviation industry, and in particular to a method for predicting flow coefficient of a multi-branch nozzle, electronic equipment and a medium. Background Art

[0002] The helicopter transmission system is the core component of aviation power transmission, and the reliability of its lubrication system directly affects the service performance of high-speed gears and bearings. Multi-branch oil injection pipelines have become the standard configuration of the main reducer lubrication system due to their advantages such as strong spatial adaptability and uniform lubrication coverage. As the terminal execution unit of the lubrication system, the flow coefficient characteristics of the nozzle directly determine the quality of oil film formation and thermal management efficiency. Traditional theory is based on the assumption of ideal fluid and derives the flow coefficient calculation formula through the Bernoulli equation. However, the flow contraction, viscous dissipation and compressibility effects existing in actual working conditions lead to significant deviations in theoretical predictions.

[0003] Existing research focuses on the influencing mechanism of single nozzle structural parameters. For example, the ASME standard constructs an empirical formula by introducing the Reynolds number Re and the geometric ratio d / D, and the Buckingham π theory establishes a correlation model between l / D and Re. However, these methods have two technical limitations: first, the representation of the pressure effect is too simplified. Especially in the low-pressure range of 0.1-0.5MPa, experimental data show that the flow coefficient and the pressure difference have a nonlinear relationship, while the existing formula still uses a linear assumption; second, there is a lack of research on the coupled flow characteristics of multi-branch nozzles. When the number of nozzles increases, the traditional theory simply superimposes the single nozzle flow without considering the turbulent interference effect caused by the branch arrangement. For example, the turbulent kinetic energy increment generated by the jet collision of the reverse arrangement nozzle can reach 1.8 times that of the circumferential arrangement, resulting in a flow prediction error of more than 12%.

[0004] More importantly, the effect of nozzle angle on flow separation has not been fully quantified. Although the empirical formula attempts to correct the angle effect through a cubic polynomial, it does not establish a coupling relationship with the pressure field. The CFD simulation revealed that the flow separation area increases by 37% when α = 30° compared to α = 0°, while the pressure correction coefficient C p The nonlinear characteristics at Δp < 0.3 MPa further amplify the prediction deviation of the angle effect. In addition, the existing technology lacks a theoretical description of the flow field synergy mechanism of multi-branch special-shaped arrangements (such as circumferential / reverse combinations), resulting in the widespread use of conservative coefficient methods in engineering design, which increases the redundant weight of the lubrication system by about 15%.

[0005] Therefore, it is urgent to develop a flow coefficient prediction method that integrates pressure-angle coupling correction and multi-branch interference effect modeling to improve the design accuracy and lightweight level of helicopter lubrication systems. Summary of the invention

[0006] The present invention provides a method for predicting the flow coefficient of a multi-branch nozzle, an electronic device and a medium, the purpose of which is to solve the problem of insufficient flow prediction accuracy of the existing method under low pressure difference and multi-nozzle layout.

[0007] To achieve the above object, the present invention provides a method for predicting a flow coefficient of a multi-branch nozzle in a first aspect, comprising the following steps:

[0008] Quantify the flow coefficient of a single nozzle under different pressure conditions;

[0009] Based on the quantified flow coefficient, the flow coefficient of a single nozzle at different angles is corrected to calculate the angle correction coefficient;

[0010] Fit the pressure correction coefficient equation, correct the flow coefficient of the single nozzle according to different pressure differences, and obtain the pressure correction coefficient;

[0011] Combining the flow coefficient, pressure correction coefficient and angle correction coefficient, the improved single nozzle flow coefficient is obtained;

[0012] Establish a multi-branch nozzle model and set the number and layout of nozzles according to actual needs;

[0013] According to the improved single nozzle flow coefficient and the number of nozzles, the total flow coefficient of the multi-branch nozzle is calculated.

[0014] Further, methods for quantifying the flow coefficient of a single nozzle under different pressure conditions include:

[0015] Obtain the geometric parameters and flow parameters of a single nozzle;

[0016] According to the geometric parameters and flow parameters, the theoretical flow coefficient of a single nozzle is calculated using any of the following formulas;

[0017]

[0018] Among them, Q m is the mass flow rate (mass flow rate of the actual fluid); c is a parameter related to the compressibility of the fluid; A 0 is the cross-sectional area of ​​the nozzle or orifice; ρ o is the fluid density at the reference state; p 2 -p 1 It is the pressure difference before and after the nozzle or orifice.

[0019] For compressible fluids, the flow coefficient can be further expressed as:

[0020]

[0021] Where γ is the specific heat capacity; R is the specific fluid constant (unit: J / (kg·K)); T represents the absolute temperature of the fluid at the nozzle inlet (unit: K);

[0022] Based on the Reynolds number, nozzle diameter to pipe diameter ratio, and nozzle length to pipe diameter ratio parameters, the flow coefficient for Reynolds number ranges from 10 to 20,000 and nozzle length to pipe diameter ratio ranges from 2 to 10 is calculated according to the following formula:

[0023]

[0024] Where Re is the Reynolds number, C du is the flow coefficient when the Reynolds number Re≈20000, l is the nozzle length, and d is the nozzle diameter;

[0025] When the Reynolds number Re>20000, the following flow coefficient formula is used for calculation:

[0026]

[0027] Alternatively, when the Reynolds number Re>20000, the following flow coefficient formula is used for calculation:

[0028]

[0029] Where D is the pipe diameter.

[0030] Furthermore, the flow coefficient of a single nozzle is corrected at different angles to calculate the angle correction coefficient. The calculation method includes:

[0031] Assigning each nozzle angle, wherein the angle ranges from 0° to 90°;

[0032] Calculate the angle correction factor using the following formula for nozzles with an angle range of 0° to 90°:

[0033] C α =-0.0000010545α 3 +0.000181563α 2 -0.00762α+0.99976(7)

[0034] Among them, C α is the angle correction coefficient, and α is the nozzle angle.

[0035] Furthermore, the pressure correction coefficient equation is fitted, and the flow coefficient of the single nozzle is corrected according to different pressure differences. The method for obtaining the pressure correction coefficient includes:

[0036] Through numerical simulation or experimental data, the flow coefficient under different pressure difference conditions under the nozzle is obtained;

[0037] Using MATLAB platform, the relationship between pressure difference and flow coefficient is fitted, and the pressure correction coefficient equation is obtained;

[0038] Through fitting, the expression of pressure correction coefficient is obtained:

[0039] C p =1.132Δp 0.1146 (8)

[0040] Among them, C p is the pressure correction coefficient, and Δp is the pressure difference before and after the nozzle.

[0041] Furthermore, by combining the flow coefficient, pressure correction coefficient and angle correction coefficient, the improved single nozzle flow coefficient is obtained using the following calculation formula:

[0042] C d ′=C d C p C α (9)

[0043] Among them, C d ' is the improved flow coefficient, C d is the flow coefficient, C p is the pressure correction factor, C α is the angle correction factor.

[0044] Furthermore, the number of nozzle branches of the multi-branch nozzle model is 2, 3 or 4, and the spacing between each branch is 5.0-30.0 mm.

[0045] Furthermore, the nozzle arrangement in the multi-branch nozzle model is any of the following:

[0046] Each nozzle branch is evenly distributed along the circumference of the pipeline;

[0047] The spraying direction of each nozzle branch is the same;

[0048] The spraying directions of adjacent nozzle branches are opposite.

[0049] Furthermore, the total flow coefficient of the multi-branch nozzle is calculated according to the following formula:

[0050]

[0051] Among them, N m is the number of nozzles.

[0052] To achieve the above-mentioned purpose, the second aspect of the present invention provides an electronic device, including a processor and a memory, wherein the processor is used to implement the steps of the multi-branch nozzle flow coefficient prediction method when executing a computer program stored in the memory.

[0053] To achieve the above-mentioned object, the third aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the multi-branch nozzle flow coefficient prediction method are executed.

[0054] Beneficial effects of the present invention:

[0055] Compared with the prior art, the present invention provides a multi-branch nozzle flow coefficient prediction method, electronic equipment and medium, which, based on the computational fluid dynamics (CFD) method, numerically analyzes the flow characteristics under different nozzle angles, pressure differences and multi-nozzle layout conditions, and improves the flow coefficient calculation formula through theoretical modeling. By introducing the angle correction coefficient and the pressure correction coefficient, the flow prediction of the single nozzle and multi-nozzle system under different working conditions is realized, the flow distribution accuracy of the lubrication system is improved, and the lubrication performance of the helicopter main reducer is optimized, and the reliability and service life of the transmission system are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0057] Figure 1 It is a flow chart of a method for predicting flow coefficient of a multi-branch nozzle disclosed in an embodiment of the present invention.

[0058] Figure 2 It is a schematic diagram of a single fuel injector pipeline disclosed in an embodiment of the present invention.

[0059] Figure 3 This is a nozzle model diagram disclosed in an embodiment of the present invention.

[0060] Figure 4 It is a comparison diagram of the mass flow rate and relative error of a single nozzle considering the angle coefficient disclosed in an embodiment of the present invention.

[0061] Figure 5 It is a diagram showing the variation of flow coefficient with nozzle angle and pressure difference disclosed in an embodiment of the present invention.

[0062] Figure 6 It is a diagram of the variation of the pressure coefficient under different pressure differences disclosed in an embodiment of the present invention.

[0063] Figure 7 It is a comparison diagram of single nozzle mass flow rate and relative error considering the pressure correction coefficient disclosed in an embodiment of the present invention.

[0064] Figure 8It is a graph showing the variation of mass flow rates of different nozzles with spacing under different pressure differences disclosed in an embodiment of the present invention.

[0065] Fig. 9 This is a relationship diagram between different pressure differences and oil mass flow rates under a double-branch nozzle disclosed in an embodiment of the present invention.

[0066] Fig.10 The diagram is a relationship diagram between different pressure differences and oil mass flow rate under a three-branch nozzle disclosed in an embodiment of the present invention.

[0067] Fig.11 This is a relationship diagram between different pressure differences and oil mass flow rates under a four-branch nozzle disclosed in an embodiment of the present invention.

[0068] Fig.12 The diagram is a relationship diagram between oil mass flow rate and pressure difference when a double nozzle is arranged anisotropically at a nozzle angle of 30° disclosed in an embodiment of the present invention.

[0069] Fig.13 The diagram is a relationship diagram between oil mass flow rate and pressure difference when a double nozzle is arranged anisotropically at a nozzle angle of 45° disclosed in an embodiment of the present invention.

[0070] Fig.14 The diagram is a relationship diagram between oil mass flow rate and pressure difference when a double nozzle is arranged anisotropically at a nozzle angle of 75° disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0071] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0072] According to an embodiment of the present invention, it should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the following method, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0073] like Figure 1 As shown, the present invention provides a method for predicting the flow coefficient of a multi-branch nozzle, which aims to establish an angle correction coefficient and a pressure correction coefficient based on the flow characteristics of a single nozzle under different pressure conditions, and apply them to the flow prediction of a multi-branch nozzle to improve the accuracy of the flow coefficient calculation. The technical solution of the present invention is described in detail through the following steps. The prediction method includes the following steps:

[0074] Step S100, quantifying the flow coefficient of a single nozzle under different pressure conditions;

[0075] When the fluid passes through the nozzle, the actual flow is affected by factors such as the orifice edge, flow contraction effect, fluid viscosity and compressibility, resulting in the actual mass flow rate being different from the ideal flow rate. To this end, the present invention introduces a flow coefficient based on the Bernoulli equation to characterize the deviation between the actual flow rate and the ideal flow rate, and its expression is as follows:

[0076]

[0077] Among them, Q m is the mass flow rate (mass flow rate of the actual fluid); c is a parameter related to the compressibility of the fluid; A 0 is the cross-sectional area of ​​the nozzle or orifice; ρ o is the fluid density at the reference state; p 2 -p 1 It is the pressure difference before and after the nozzle or orifice.

[0078] For compressible fluids, the flow coefficient can be further expressed as:

[0079]

[0080] Where γ is the specific heat capacity; R is the specific fluid constant (unit: J / (kg·K)); and T represents the absolute temperature of the fluid at the nozzle inlet (unit: K).

[0081] According to Buckinghamπ theory, the main parameters affecting the flow coefficient are the pressure difference Δp, the ratio of nozzle diameter to pipe diameter, and the ratio of nozzle length to pipe diameter. When the Reynolds number ranges from 10 to 20,000 and the ratio of nozzle length to pipe diameter ranges from 2 to 10, the flow coefficient can be predicted by the following empirical formula:

[0082]

[0083] Where Re is the Reynolds number, C du is the flow coefficient when the Reynolds number Re≈20000, l is the nozzle length, and d is the nozzle diameter (see Figure 2 );

[0084] For steady compressible flow at high Reynolds numbers, the flow coefficient remains essentially constant when Re>20000. Based on the above theory and Reynolds numbers in various ranges, a more general formula for predicting the flow coefficient of a single nozzle is established:

[0085]

[0086] Alternatively, when the Reynolds number Re>20000, the following flow coefficient formula is used for calculation:

[0087]

[0088] Where D is the pipe diameter.

[0089] It is understandable that the geometric parameters and flow parameters of a single nozzle need to be obtained first, wherein the geometric parameters include: nozzle diameter, pipeline diameter, ratio of nozzle length to diameter, etc.; flow parameters include: Reynolds number, inlet pressure, outlet pressure, etc. According to the obtained geometric parameters and flow parameters, according to the above formula (1), (2), (3), (4), (5) or (6), the theoretical flow coefficient of a single nozzle can be calculated, which is used to measure the deviation between the actual flow and the ideal flow; that is, when the above formula (1)-(6) calculates the nozzle flow coefficient, only factors such as nozzle size and pressure difference are considered, but the influence of nozzle angle and pressure effect is ignored. In the subsequent steps, this embodiment introduces correction coefficients for nozzle angle and pressure difference to achieve the purpose of improving the accuracy of flow prediction, so that it can better adapt to complex situations such as different angles and multi-nozzle arrangements.

[0090] Step S200: Based on the quantified flow coefficient, the flow coefficient of the single nozzle at different angles is corrected to calculate the angle correction coefficient;

[0091] The effect of nozzle angle on flow coefficient is determined by multiple factors. Especially when the nozzle angle changes, the injection flow and flow characteristics will change significantly. Figure 4 The flow coefficient and mass flow rate obtained by numerical simulation under different pressure difference (Δp = 0.1 ~ 0.5MPa) and single nozzle angle (0 ° ~ 90 °) conditions are shown. It can be observed that the overall trend of the flow calculated based on the improved theoretical equation is highly consistent with the numerical simulation results, and under the condition of lower pressure difference, the flow coefficient shows different change patterns with the change of nozzle angle.

[0092] In this step, the flow coefficients at different nozzle angles are first obtained through numerical simulation or experiment, and then these flow coefficients are corrected using equations (such as Formula 1, Formula 6, and Formula 7). In order to accurately calculate the angle correction coefficient, a correction empirical formula based on the nozzle angle is proposed:

[0093] C α =-0.0000010545α 3 +0.000181563α 2 -0.00762α+0.99976 (7)

[0094] Among them, C αis the angle correction coefficient, and α is the nozzle angle.

[0095] The formula is obtained by fitting experimental data and can correct the flow coefficient within the nozzle angle variation range of 0°≤a≤90°.

[0096] like Figure 5 As shown, further analysis shows that the flow coefficient presents a nonlinear change trend as the nozzle angle increases, especially when the nozzle angle increases from 0° to 30°, the flow coefficient decreases significantly; when the nozzle angle is between 30° and 90°, the flow coefficient gradually increases.

[0097] Step S300, fitting a pressure correction coefficient equation, correcting the flow coefficient of a single nozzle according to different pressure differences, and obtaining a pressure correction coefficient;

[0098] The core of step S300 is to fit the pressure correction coefficient equation according to different pressure differences, so as to correct the flow coefficient of a single nozzle. Figure 4 It can be seen that there are significant differences in the effect of pressure difference on the flow coefficient, especially under low pressure difference conditions, the flow coefficient increases slightly with the change of inlet pressure, but it does not show a linear relationship, but shows a small change range. This phenomenon shows that the mass flow of a single nozzle is mainly controlled by the pressure difference before and after the nozzle, rather than simply determined by the flow coefficient.

[0099] In order to solve the problem of inaccurate flow coefficient caused by pressure difference, this step proposes an improved theoretical equation to correct the original flow coefficient by pressure correction coefficient. The pressure correction coefficient is defined as a function related to the pressure difference. By analyzing and fitting the flow coefficient data under different pressure differences (0.1MPa to 0.5MPa), the formula of pressure correction coefficient is obtained:

[0100] C p =1.132Δp 0.1146 (8)

[0101] Among them, C p is the pressure correction coefficient, and Δp is the pressure difference before and after the nozzle.

[0102] This formula uses the power function form of pressure difference, which can accurately describe the influence of pressure difference on flow coefficient, especially the nonlinear characteristics under low pressure conditions. Figure 6 The variation of the correction coefficient for different pressure differences at different nozzle angles (0°, 45°, 90°) is shown, and the correction coefficient is obtained by processing the normalized data using the curve fitting method in the MATLAB platform.

[0103] Step S400, combining the flow coefficient, the pressure correction coefficient and the angle correction coefficient to obtain an improved single nozzle flow coefficient;

[0104] The correction coefficients obtained in the previous steps are comprehensively applied to accurately correct and optimize the nozzle flow coefficient to improve the accuracy of flow prediction. In practical applications, the accuracy of the nozzle flow coefficient is directly related to the flow rate and injection effect of the lubricating oil. Therefore, the improved flow coefficient can provide a more reliable theoretical basis for the optimization design of the entire injection system.

[0105] In step S400, the preliminary flow coefficient of a single nozzle under specific pressure difference and angle conditions is first calculated by the flow coefficient (Formula 6). Then, based on the correction coefficients obtained in steps S200 and S300, the angle correction coefficient and the pressure correction coefficient are corrected respectively. Specifically, the angle correction coefficient is used to correct the effect of nozzle angle change on the flow coefficient, while the pressure correction coefficient is used to correct the nonlinear effect of pressure difference on the flow coefficient. After combining the three coefficients, the improved flow coefficient calculation formula is:

[0106] C d ′=C d C p C α (9)

[0107] Among them, C d ' is the improved flow coefficient, C d is the flow coefficient, C p is the pressure correction factor, C α The improved flow coefficient calculation formula can improve the calculation accuracy of the flow coefficient under different conditions (such as different nozzle angles, pressure differences, nozzle arrangements, etc.).

[0108] Figure 6 and Figure 7 The comparison between the improved method and the numerical simulation results under different nozzle angles and pressure differences is shown in Figure 2. Figure 7 As shown, it can be observed that the corrected flow coefficient is highly consistent with the numerical simulation results, especially under low pressure difference and large angle conditions, the improved flow coefficient prediction accuracy is high, and the average relative error is reduced to about 2%. This shows that the proposed improved method effectively makes up for the shortcomings of traditional theory in flow prediction and can provide high-precision flow coefficient prediction under a wider range of working conditions.

[0109] Step S500, establishing a multi-branch nozzle model, and setting the number and layout of the nozzles according to actual needs;

[0110] Step S600: Calculate the total flow coefficient of the multi-branch nozzle according to the improved single nozzle flow coefficient and the number of nozzles.

[0111] In the aviation industry, especially in high-load systems such as helicopter main reducers, multiple nozzles are often used for oil injection and cooling. Therefore, accurate prediction of the flow characteristics of the multi-branch nozzle system is crucial to improve the efficiency and performance of the entire system.

[0112] In this step, the geometric structure of the multi-branch nozzle is designed, and the number of nozzles is set (such as 2, 3, or 4 nozzles). Figure 3 As shown, the nozzle arrangement can be selected according to actual needs (see Figure 3 (c) in-line arrangement, reverse arrangement, circumferential arrangement, etc.), Figure 3 (a) is the layout diagram of a single nozzle. Figure 3 (b) is a structural diagram of multiple nozzles arranged vertically.

[0113] In the modeling of the multi-branch nozzle, it is necessary to calculate the flow coefficient of each nozzle according to the working conditions of each nozzle (such as nozzle angle, nozzle spacing, nozzle diameter, etc.), and combine the flow distribution of each nozzle to obtain the total flow coefficient of the entire injection system. According to the present embodiment, the flow coefficient of the multi-branch nozzle in step S500 will take into account factors such as the number of nozzles, nozzle spacing, and nozzle angle, so as to achieve accurate prediction of the flow characteristics of the entire multi-nozzle system.

[0114] Furthermore, the improved single nozzle flow coefficient (combined with the pressure correction coefficient, angle correction coefficient and flow coefficient) is used to calculate the flow of each branch nozzle to obtain the total flow coefficient of the multi-nozzle system. The total mass flow of the multi-branch nozzle is proportional to the number of nozzles, so the flow coefficient can be predicted by the following formula:

[0115]

[0116] Among them, N m is the number of nozzles.

[0117] Figure 8 and Figure 9-11 The flow characteristics of the multi-nozzle system with different nozzle numbers and arrangements are shown. Figure 8 The results show the changes in the mass flow of multiple nozzles under different pressure differences (0.1MPa to 0.5MPa), different nozzle spacings (5-30mm) and a fixed nozzle angle of 90°. The results show that the flow rate changes less with the increase of the nozzle spacing, which indicates that the total mass flow of the nozzle is mainly affected by the pressure difference, nozzle angle and number of nozzles, while the effect of the spacing is relatively weak.

[0118] Fig. 9 The relationship between different pressure differences and oil mass flow rate under the double-branch nozzle is shown in Figure 2. Fig.10 The relationship between different pressure differences and oil mass flow rate under the three-branch nozzle is shown in Figure 2. Fig.11 This is the relationship between different pressure differences and oil mass flow rate under the four-branch nozzle.

[0119] Figure 9-11 The relationship between the total mass flow rate and different pressure differences of different branch nozzles with a nozzle angle of 90° is further demonstrated, and the numerical simulation results are directly compared with the theoretical results calculated based on formulas (1), (6), (7) and (9). The results show that the improved theoretical method is also applicable to the flow prediction of multi-branch nozzles, and the maximum error does not exceed 10%.

[0120] In addition, in industrial applications, the branch arrangement of nozzles usually has three forms: same direction, opposite direction and circumferential arrangement, such as Figure 12-14 As shown, the oil mass flow rate of numerical simulation is compared with the theoretical results calculated by formula (1), formula (6), formula (7) and formula (9). Fig.12 The relationship between oil mass flow rate and pressure difference when the double nozzles are arranged anisotropically at a nozzle angle of 30°; Fig.13 The relationship between oil mass flow rate and pressure difference when the double nozzles are arranged anisotropically at a nozzle angle of 45°; Fig.14 The relationship between oil mass flow rate and pressure difference when double nozzles are arranged anisotropically at a nozzle angle of 75°.

[0121] From the overall trend, the improved theoretical equation can better predict the mass flow rate changes under different pressure conditions, with a maximum relative error of about 6.3%. Further analysis shows that for double-branch nozzles with different nozzle angles, the layout has a certain influence on the prediction error. For example, when the nozzle angle is 30°, the average error of the same direction layout is 1.5%, the opposite direction layout is 3.4%, and the circumferential layout is 5.4%. When the nozzle angle is 45°, the corresponding average errors are 1.5%, 3.5%, and 3.7%; and when the nozzle angle is 75°, the average errors are 0.9%, 2.1%, and 1.9%, respectively. These results show that the improved formula proposed in this scheme can be well applied to the flow prediction of double-branch nozzles under different branch layouts.

[0122] In addition, from the perspective of the change in total mass flow rate, the nozzles arranged circumferentially show the highest flow rate, followed by those arranged in the same direction, while those arranged in the opposite direction have a relatively low flow rate. This phenomenon can be explained by the change in turbulence intensity. When the branches are arranged circumferentially, the turbulence intensity is the lowest, so the flow resistance is the lowest; the turbulence intensity of the branches arranged in the same direction is slightly higher, and the resistance increases; while the turbulence intensity of the branches arranged in the opposite direction is the highest, and the suppression effect on the flow rate is the most significant.

[0123] By comparing numerical simulation with theoretical calculation, the applicability and prediction accuracy of the proposed improved method under different nozzle configurations can be verified.

[0124] According to another aspect of an embodiment of the present application, there is further provided an electronic device, including a processor and a memory, wherein the processor is configured to implement the steps of the method when executing a computer program stored in the memory.

[0125] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0126] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0127] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0128] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0129] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for predicting the flow coefficient of a multi-branch nozzle, characterized in that: The steps include: Quantify the flow coefficient of a single nozzle under different pressure conditions; Based on the quantified flow coefficient, the flow coefficient of a single nozzle at different angles is corrected to calculate the angle correction coefficient; Fit the pressure correction coefficient equation, correct the flow coefficient of the single nozzle according to different pressure differences, and obtain the pressure correction coefficient; Combining the flow coefficient, pressure correction coefficient and angle correction coefficient, the improved single nozzle flow coefficient is obtained; Establish a multi-branch nozzle model and set the number and layout of nozzles according to actual needs; According to the improved single nozzle flow coefficient and the number of nozzles, the total flow coefficient of the multi-branch nozzle is calculated.

2. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1, characterized in that: Methods for quantifying the flow coefficient of a single nozzle at different pressure conditions include: Obtain the geometric parameters and flow parameters of a single nozzle; According to the geometric parameters and flow parameters, the theoretical flow coefficient of a single nozzle is calculated using any of the following formulas; Among them, Q m is the mass flow rate (mass flow rate of the actual fluid); c is a parameter related to the compressibility of the fluid; A0 is the cross-sectional area of ​​the nozzle or orifice; ρ o is the fluid density at the reference state; p2-p1 is the pressure difference before and after the nozzle or orifice. For compressible fluids, the flow coefficient can be further expressed as: Where γ is the specific heat capacity; R is the specific fluid constant (unit: J / (kg·K)); T represents the absolute temperature of the fluid at the nozzle inlet (unit: K); Based on the Reynolds number, nozzle diameter to pipe diameter ratio, and nozzle length to pipe diameter ratio parameters, the flow coefficient for Reynolds number ranges from 10 to 20,000 and nozzle length to pipe diameter ratio ranges from 2 to 10 is calculated according to the following formula: Where Re is the Reynolds number, C du is the flow coefficient when the Reynolds number Re≈20000, l is the nozzle length, and d is the nozzle diameter; When the Reynolds number Re>20000, the following flow coefficient formula is used for calculation: Alternatively, when the Reynolds number Re>20000, the following flow coefficient formula is used for calculation: Where D is the pipe diameter.

3. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1, characterized in that: The method for calculating the angle correction coefficient by correcting the flow coefficient of a single nozzle at different angles includes: Assigning each nozzle angle, wherein the angle ranges from 0° to 90°; Calculate the angle correction factor using the following formula for nozzles with an angle range of 0° to 90°: C α ＝-0.0000010545α 3 +0.000181563α 2 -0.00762α+0.99976(7) Among them, C α is the angle correction coefficient, and α is the nozzle angle.

4. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1, characterized in that: Fitting the pressure correction coefficient equation, correcting the flow coefficient of a single nozzle according to different pressure differences, and obtaining the pressure correction coefficient include: Through numerical simulation or experimental data, the flow coefficient under different pressure difference conditions under the nozzle is obtained; Using MATLAB platform, the relationship between pressure difference and flow coefficient is fitted, and the pressure correction coefficient equation is obtained; Through fitting, the expression of pressure correction coefficient is obtained: C p =1.132Δp 0.1146 (8) Among them, C p is the pressure correction coefficient, and Δp is the pressure difference before and after the nozzle.

5. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1, characterized in that: Combining the flow coefficient, pressure correction coefficient and angle correction coefficient, the improved single nozzle flow coefficient is obtained using the following calculation formula: C d ′=C d C p C α (9) Among them, C d ' is the improved flow coefficient, C d is the flow coefficient, C p is the pressure correction factor, C α is the angle correction factor.

6. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1, characterized in that: The number of nozzle branches of the multi-branch nozzle model is 2, 3 or 4, and the distance between each branch is 5.0-30.0 mm.

7. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1 or 6, characterized in that: The nozzle arrangement in the multi-branch nozzle model is any of the following: Each nozzle branch is evenly distributed along the circumference of the pipeline; The spraying direction of each nozzle branch is the same; The spraying directions of adjacent nozzle branches are opposite.

8. The method for predicting the flow coefficient of a multi-branch nozzle according to claim 1, characterized in that: The total flow coefficient of the multi-branch nozzle is calculated according to the following formula: Among them, N m is the number of nozzles.

9. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the processor is used to implement the steps of the multi-branch nozzle flow coefficient prediction method as claimed in any one of claims 1 to 8 when executing the computer program stored in the memory.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the multi-branch nozzle flow coefficient prediction method according to any one of claims 1 to 8 are executed.

Images