Multi-index comprehensive evaluation method and system for injection performance of diesel injector
By employing a multi-index comprehensive evaluation method, which integrates nozzle flow capacity, spray geometry, and cavitation damage risk, the problem of a unified standard for diesel engine nozzle evaluation is solved. This enables high-resolution characterization of injection performance and cross-operating condition assessment, and provides a basis for nozzle structure optimization.
Patent Information
- Application Number
- CN202511706136.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-20
- Publication Date
- 2026-02-10
AI Technical Summary
The current evaluation of diesel engine nozzles lacks a unified standard, has a single indicator dimension, makes it difficult to compare across operating conditions, and makes it difficult to achieve high-resolution characterization and reliable judgment of injection performance.
A multi-index comprehensive evaluation method is adopted, which integrates nozzle flow capacity, spray geometry, spray propulsion capacity and cavitation damage risk. Through normalization and adaptive weighting based on operating conditions, a reproducible and traceable comprehensive score and classification judgment are formed.
Within the same framework, improve the discrimination resolution and physical consistency of injection performance, enhance data comparability across platforms and operating conditions, and provide a basis for nozzle structure optimization.
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Figure CN121504274A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of internal combustion engine fuel injection technology, more particularly to a multi-index comprehensive evaluation method and system for the injection performance of a diesel engine injector. BACKGROUND
[0002] The electronically controlled high-pressure common rail fuel injection system has an important influence on the thermal efficiency and emission control of diesel engines. Key factors related to fuel economy and emissions include jet breakup and atomization characteristics, as well as precise control of injection quantity and phase.
[0003] The injector nozzle is a core component that connects the upstream fuel supply and the downstream jet spray. Inside the nozzle, there is a small-scale, high-turbulence, multi-phase transient flow. This flow process is closely related to the flow capacity, spray characteristics, operational reliability and durability of the nozzle, and directly affects the combustion and emission performance of the engine.
[0004] Existing research and engineering practice show that the occurrence and evolution of cavitation flow inside the nozzle is significantly related to the nozzle geometry. Differences in geometry can change the local pressure drop and flow velocity distribution, affecting the cavitation intensity and position distribution, and ultimately changing the spray cone angle, penetration and breakup scale, resulting in differences in the injection performance of the engine injector.
[0005] In engineering practice, the evaluation and optimization of nozzle performance usually rely on two types of information sources: one is the spray test images obtained based on visualization methods such as shadowgraph; the other is the two-phase flow numerical simulation results of internal flow and near-field spray area obtained based on computational fluid dynamics (CFD) simulation software. However, the two types of information sources lack uniformity in terms of index caliber, data quality and processing flow, making it difficult to form a comprehensive evaluation standard and multi-angle parameter system. At the same time, existing evaluation schemes focus on a single geometry or a single flow quantity, lack a system that simultaneously models the nozzle outlet cross-sectional flow capacity, macroscopic spray morphology parameters and cavitation damage risk, and is difficult to achieve high-resolution characterization and reliable discrimination of injection performance under the same dimension.
[0006] Therefore, engineering applications urgently need to establish a unified process and standardized index set that connects "data acquisition-data processing-comprehensive evaluation", to comprehensively quantify the nozzle structure in a reproducible and traceable manner under the same scale, in order to support structure comparison and optimization design across operating conditions and platforms. SUMMARY
[0007] The present application aims at the problems of lack of unified standard, single index dimension and difficulty in cross-working condition comparison for existing nozzles, and proposes a multi-index comprehensive evaluation method and system for injection performance of diesel engine injectors.
[0008] In order to achieve the above purpose, the present application adopts the following technical solutions: A multi-index comprehensive evaluation method for injection performance of diesel engine injectors, characterized in that it comprises the following steps: S01. Data acquisition: obtain key spray parameters of the nozzle, including nozzle outlet flow coefficient Cd, liquid phase near-field diffusion angle , spray-like penetration distance P E and cavitation risk index E ero ; S02. Data processing: normalize the spray parameters to enable comparison of different dimension indexes in the same latitude; S03. Weight setting: set the weight of each index according to the engine combustion working condition; S04. Comprehensive scoring: construct a comprehensive evaluation function to score the nozzle structure; S05. Comprehensive decision: determine the advantages and disadvantages of the nozzle structure according to the scoring results of the comprehensive scoring.
[0009] Further, the nozzle outlet flow coefficient C d is defined as:
[0010] wherein, Q a is the actual mass flow rate at the nozzle outlet, A out is the outlet cross-sectional area of the nozzle, is the liquid density, which can be considered as a constant in incompressible flow, P in is the fuel injection pressure, P out is the outlet pressure.
[0011] Further, the liquid phase near-field diffusion angle In the experiment, the spray boundary is identified by spray near-field image, and the included angle between the two boundary lines formed by connecting the center of the spray hole outlet is calculated. In the numerical simulation, the liquid phase near-field distribution surface is characterized by the liquid volume fraction α l =0.1 isosurface, which is approximately the spray near-field diffusion angle .
[0012] Further, the class spray penetration distance P E is defined as:
[0013] wherein, AKE is the average axial kinetic energy of the fluid on the outlet cross section of the spray hole, NAKE is the average non-axial kinetic energy, TKE is the turbulent kinetic energy, ATE is the average non-axial kinetic energy of the fluid on the outlet cross section of the spray hole.
[0014] Further, the cavitation risk index E ero Based on the ZGB cavitation model of bubble dynamics, combined with the integral value of the gas phase condensation rate on the wall surface at the near-wall surface of the spray hole, the gas phase condensation rate R c is defined as:
[0015] wherein, F cond is the condensation coefficient, taking a value of 0.01, v is the gas volume fraction, v is the gas density, R B is the initial bubble radius, taking a value of 0.001 mm, P is the local flow field pressure, P v is the saturated vapor pressure of the working medium (diesel oil), l is the liquid density.
[0016] The application discloses a kind of diesel oil injector injection performance multi-index comprehensive evaluation method's evaluation system, comprising: parameter acquisition module, data processing module, weight setting module and comprehensive evaluation module, the parameter acquisition module is used to obtain the liquid phase near-field diffusion angle of nozzle, spray-like penetration distance, flow coefficient and cavitation erosion risk index;The data processing module is used to carry out normalization processing to the spray parameter;The weight setting module is used to set the weight of each index according to engine combustion condition;The comprehensive evaluation module is used to score nozzle structure based on comprehensive evaluation function, and output advantage and disadvantage determination result.
[0017] Further, the parameter acquisition module includes: image acquisition unit and image processing unit, the image acquisition unit is used to obtain nozzle near-field spray image based on shadow method, and the image processing unit is used to extract spray boundary and calculate liquid phase near-field diffusion angle by edge detection and morphological operation.
[0018] Further, the parameter acquisition module further includes: numerical simulation unit and data interface unit, the numerical simulation unit is used to calculate liquid phase volume fraction liquid phase volume fraction α l =0.1 isosurface to obtain spray near-field diffusion angle , axial kinetic energy and total kinetic energy of nozzle outlet cross section to obtain spray-like penetration distance P E And calculate mass flow to obtain flow coefficient C d And cavitation erosion risk index based on ZGB cavitation model E ero ; the data interface unit is used to import original data from external test bench or simulation platform.
[0019] Further, the comprehensive evaluation module includes: scoring engine and decision engine, scoring engine calculates comprehensive score according to normalized index and weight, and decision engine carries out grade division and advantage and disadvantage determination to nozzle structure according to threshold value, and generates key report including basic information, specific data, comprehensive score, nozzle grade and optimization suggestion.
[0020] The application has the following beneficial effects: 1. In the same evaluation framework, the injection nozzle flow capacity ( C d ), spray geometry ( ), spray propulsion capacity ( P E ) and cavitation erosion damage risk ( E ero ) are jointly described, and the discrimination resolution and physical consistency of injection performance are improved. 2. The present application significantly improves the data comparability and result reproducibility across platforms and operating conditions by normalizing each parameter and introducing weight settings associated with engine operating conditions, realizes multi-dimensional evaluation of the injection performance of the fuel injector, and provides quantitative basis for nozzle structure optimization. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 Flow chart of the multi-index comprehensive evaluation method and system for the injection performance of the diesel engine fuel injector of the present application; Figure 2 Schematic diagram of the test bench used by the image data acquisition unit of the present application; Figure 3 Liquid phase near-field diffusion angle obtained in the test of the present application Schematic diagram of the spray near-field image processing method used by the present application; Figure 4 Liquid phase near-field diffusion angle obtained in the numerical simulation of the present application Schematic diagram of the liquid phase volume fraction αl=0.1 isosurface used by the present application; Figure 5 Schematic diagram of the numerical simulation calculation domain of the nozzle of a certain 9-hole high-speed marine diesel engine fuel injector in Example 2 of the present application; Figure 6 Internal flow field result diagram in the numerical simulation of the nozzle of a certain 9-hole high-speed marine diesel engine fuel injector in Example 2 of the present application; Figure 7 Cavitation flow state and liquid phase near-field distribution result diagram in the numerical simulation of the nozzle of a certain 9-hole high-speed marine diesel engine fuel injector in Example 2 of the present application; Figure 8 Pressure distribution result diagram in the numerical simulation of the nozzle of a certain 9-hole high-speed marine diesel engine fuel injector in Example 2 of the present application; Figure 9 Vapor phase volume fraction (αv) distribution result diagram of the upper and lower wall surfaces of the injection hole in the numerical simulation of the nozzle of a certain 9-hole high-speed marine diesel engine fuel injector in Example 2 of the present application; α v Figure 10 Condensation rate distribution result diagram of the gas phase of the upper and lower wall surfaces of the injection hole in the numerical simulation of the nozzle of a certain 9-hole high-speed marine diesel engine fuel injector in Example 2 of the present application. DETAILED DESCRIPTION
[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.
[0023] This application provides a detailed explanation of the technical solution in conjunction with the accompanying drawings and embodiments to fully reveal the features of technological innovation. It should be noted that the interpretation of technical terms in this specification follows the following unified rules: the directional descriptions (such as "center", "longitudinal", "lateral") and sequence identifiers (such as "first", "second") used in the illustrations are only used to distinguish technical features and do not constitute a limitation on the entity structure. The spatial orientation is adaptably adjusted based on standard mapping coordinates, and the sequence identifier does not indicate the importance or quantity limit of the feature. "Multiple" specifically refers to two or more non-specific sets. Mechanical relationship terms such as "installation" and "connection" should be systematically understood, including but not limited to physical connection methods such as fixed connection, detachable connection or integral molding, as well as the action relationship of direct, indirect or through medium conduction, and covering multi-dimensional energy transfer forms such as mechanical, electrical, and electromagnetic. The "up / down" directional relationship between features includes three dimensions: geometric projection, spatial topology and parameter comparison, corresponding to the technical implementation of positive orientation, oblique orientation and horizontal height difference, respectively. The operational terms such as "fixed" and "set" are implicitly expandable in interpretation unless otherwise specified. Based on a complete understanding of the technical solution, those skilled in the art can derive various alternative implementation schemes that conform to the technical principles of this application.
[0024] Example 1
[0025] like Figure 1 As shown in the figure, this embodiment discloses a multi-index comprehensive evaluation method for the injection performance of diesel engine injectors, including the following steps: S01. Data Acquisition: To acquire raw data of key nozzle parameters, the test bench used in the image data acquisition unit of this invention is as follows: Figure 2 As shown, in the experiment, fuel from the tank is filtered by the fuel filter, then pressurized by the low-pressure fuel pump and supplied to the high-pressure fuel pump. The high-pressure fuel pump further pressurizes the fuel and supplies it to the common rail for pressure stabilization. Finally, the high-pressure fuel is delivered through fuel lines to the solenoid valve common rail injector. During the experiment, the ECU (Electronic Control Unit) sends an injection signal, and simultaneously, the ECU provides a TTL synchronization signal to trigger the camera to start taking pictures.
[0026] The parameters include the nozzle outlet flow rate coefficient. C d Liquid phase near-field diffusion angle Spray penetration distance P E and cavitation risk index E ero .in: nozzle outlet flow coefficient C d Defined as:
[0027] wherein, Q a is the actual mass flow rate at the exit of the orifice, A out is the exit cross-sectional area of the nozzle, is the liquid density, which can be considered constant in incompressible flow, P in is the fuel injection pressure, P out is the exit pressure.
[0028] Liquid phase near-field spread angle In the visualization experiment, the liquid phase near-field spread angle obtained in the experiment of the present application is The spray near-field image processing method used is as shown in Figure 3 The liquid phase near-field spread angle is calculated by identifying the spray boundary in the spray near-field image and calculating the included angle of the two boundary lines formed by connecting the center of the orifice exit, In the numerical simulation, the liquid phase near-field spread angle obtained in the numerical simulation of the present application is The liquid phase volume fraction αl=0.1 isosurface used is as shown in Figure 4 The liquid phase volume fraction αl=0.1 isosurface is used to represent the liquid phase near-field distribution surface, which is approximately the spray near-field spread angle α l . .
[0029] Pseudo-spray penetration distance P E is defined as:
[0030] wherein, AKE is the average axial kinetic energy of the fluid on the orifice exit cross-section, NAKE is the average non-axial kinetic energy, TKE is the turbulent kinetic energy, ATE is the average non-axial kinetic energy of the fluid on the orifice exit cross-section.
[0031] Cavitation risk index E ero Based on the ZGB cavitation model of bubble dynamics, combined with the integral value of the gas phase condensation rate on the wall surface at the orifice near-wall surface, the gas phase condensation rate R c is defined as:
[0032] wherein, F cond Condensation coefficient, 0.01, v Gas phase volume fraction, v Gas phase density, R B Initial bubble radius, 0.001 mm, P Local flow field pressure, P v Saturation vapor pressure of working fluid (diesel), l Liquid phase density.
[0033] S02. Data processing: To achieve the comparability of different dimensional and directional spray indicators in the same scale, the present application adopts a unified normalization process for { C d , , P E , E ero} To improve the robustness and comparability of different dimensional and directional indicators in the normalization process, the present application calculates the quantile of each indicator before scale mapping and performs extreme value clipping, clips the original value x to the interval of[ P 5, P 95 ] to reduce the influence of abnormal points on subsequent scale mapping.
[0034] In terms of directionality setting, according to the physical meaning of the indicator, C d , and P E are considered as benefit type (the larger the value, the better), and E ero is considered as cost type (the smaller the value, the better). For benefit and cost type indicators, quantile Min-Max normalization is adopted: Benefit type adopts:
[0035] Cost type adopts:
[0036] And the results are clipped to [0, 1]. Replace the global minimum / maximum value with quantile to enhance the robustness to long tail and abnormality. The final output normalized indicator vector is:
[0037] S03. Weight setting: This invention proposes that the comprehensive evaluation of injector nozzle performance should not be based on a single optimal indicator, but rather on the nozzle outlet flow coefficient. C d Liquid phase near-field diffusion angle Spray penetration distance P E and cavitation risk index E ero There are interdependent relationships among these factors, and their relative importance varies depending on the engine combustion conditions and design objectives. Therefore, the comprehensive evaluation module automatically assigns weights to each indicator based on preset operating conditions and constraints. Specifically: For small-bore engines, priority should be given to improving... The weights are adjusted to promote near-field mixing, while... P E Keep it within a moderate range to avoid excessive penetration. C d Meets the requirements for injection volume and response. E ero Keep within the safe limit; For large-bore engines, priority should be given to improving... , P E and C d The weighting is used to ensure that the spray reaches the target area, while also... E ero Keep within the safe limit; For operating conditions where economy and thermal efficiency are prioritized, the four indicators are balanced to achieve stable spray volume, reasonable spray pattern and acceptable risk level. For operating conditions where durability and lifespan are the priorities, E ero Set as a hard constraint, and apply it under the premise of satisfying the constraint. , P E and C d Perform secondary optimizations.
[0038] In one implementation, the system provides a library of initial weight values for rapid deployment. W 1. Characterizing the nozzle outlet flow coefficient C d Weights, in order to W 2. Characterizing the near-field diffusion angle of the liquid phase Weights, in order to W 3. Characterization of spray penetration distance P E Weights, in order to W 4. Characterization of cavitation risk index E ero The initial value of the weight can be: For small-bore engines: w 1, w 2, w 3, w 4]= [0.20, 0.35, 0.25, 0.20]; For large-bore engines: w 1, w 2, w 3, w 4]= [0.30, 0.25, 0.25, 0.20]; For economy and thermal efficiency priority operating conditions: w 1, w 2, w 3, w 4]= [0.25, 0.25, 0.25, 0.25]; For durability and lifetime priority operating conditions: w 1, w 2, w 3, w 4]= [0.20, 0.25, 0.25, 0.30].
[0039] Final output weight vector:
[0040] S04. Comprehensive evaluation: The comprehensive evaluation module of the present application includes two parts: a scoring engine and a decision engine. The scoring engine is used to calculate the comprehensive score of the nozzle structure / operating condition combination according to the normalized indicators and weights. The decision engine is used to grade and determine the advantages and disadvantages of the comprehensive score and key constraint indicators according to pre-set or adaptive thresholds, and output a report. Specifically: The scoring engine receives the normalized indicator vector output by the data processing module and the weight vector .
[0041] The scoring engine calculates the comprehensive score:
[0042] The decision engine grades and determines the advantages and disadvantages of the comprehensive score S . In one embodiment, the grade threshold is set as: A level (excellent): S T A ; B level (good): T B S T A ; C (Medium) : T C S T B ; D (Poor) : S T D .
[0043] The output report includes injector nozzle basic information, specific data, comprehensive score, nozzle grade, and optimization suggestions.
[0044] To implement the above method, the embodiment further provides a multi-index comprehensive evaluation system for diesel engine injector injection performance, which comprises: a parameter acquisition module, configured to acquire C d , , P E , E ero . The module comprises: an image acquisition unit and an image processing unit, configured to acquire a near-field spray image based on a shadow method, perform edge detection and morphological operation to calculate .
[0045] a numerical simulation unit or a data interface unit, configured to use an ANSYS Fluent built-in VOF model to calculate liquid phase volume fraction of the liquid phase volume fraction α l = 0.1 isosurface to obtain a spray near-field diffusion angle , calculate AKE / NAKE / TKE / ATE to obtain P E , calculate mass flow to obtain C d , and output E ero based on a ZGB cavitation model.
[0046] a data processing module, configured to perform normalization processing on the above parameters.
[0047] a weight setting module, configured to set and update the weight of each index according to the engine combustion working condition.
[0048] The comprehensive evaluation module includes a scoring engine and a decision engine. The scoring engine calculates the comprehensive score based on normalized indicators and weights, while the decision engine classifies levels based on thresholds and generates a report that includes basic information, specific data, comprehensive score, nozzle level, and optimization suggestions.
[0049] Example 2
[0050] like Figures 5-10 As shown in the figure, this embodiment discloses a multi-index comprehensive evaluation method and system for the injection performance of a diesel engine injector, and its application in the numerical simulation of the injection process of a 9-hole marine high-speed diesel engine injector.
[0051] Object and Objective: This embodiment focuses on a comprehensive evaluation of the performance of a 9-hole marine high-speed diesel engine injector. The objective is to consider both nozzle flow capacity and other factors. C d ), spray geometry ( ), spray propulsion capability ( P E ) and the risk of damage caused by cavitation ( E ero This allows for a multi-dimensional evaluation of the injector's injection performance and provides a quantitative basis for nozzle structure optimization.
[0052] Computational domain and geometric parameters; such as Figure 5 As shown, due to the high symmetry of the nozzle computational domain, a 1 / 9 symmetric model is adopted for the fluid domain to reduce computational costs and maintain physical consistency. The main geometric parameters of the nozzle are shown in Table 1.
[0053]
[0054] Table 1
[0055] Physical Model and Solver Settings: In ANSYS Fluent software, the solution is based on the RSM turbulence model within the RANS method, combining the VOF multiphase flow model and the ZGB cavitation model. During the calculation, the implicit finite volume method (FVM) is used to solve the mathematical equations, combined with a spatiotemporal discretization scheme based on a pressure solver. Specifically, the SIMPLEC (Semi-Implicit Method for Pressure Linked Equations-Consistent) algorithm is used to couple the velocity and pressure fields. Second-order upwind schemes are used for density, turbulent transport, and Reynolds stress terms, while the QUICK algorithm is used for discretization of the momentum equation. The compressive algorithm is used for discretization of the vapor phase volume fraction transport equation, and the PRESTO! scheme is used for solving the pressure interpolation term. A bounded second-order implicit scheme is used for discretization of the time term, with a fixed time step of 3 × 10⁻⁶. -8The grid boundary layer is set with 5 layers of fine mesh, with a minimum mesh size of 10 μm. Pressure inlet and pressure outlet boundary conditions are used, and symmetry boundary conditions are used on the symmetry plane. In actual operation, the injection pressure of the high-pressure common rail system of this type of injector is designed to be 180 MPa, and the back pressure is determined according to the exhaust system design. Combining the pressure drop from the actual common rail to the injection pressure boundary of the computational domain, the numerical calculation in this embodiment uses the injection pressure and back pressure under real operating conditions, that is, the injection pressure is 130 MPa and the back pressure is 20 MPa.
[0056] The internal flow field results of a 9-hole marine high-speed diesel engine injector nozzle obtained by numerical simulation are as follows: Figure 6 As shown, cavitation flow state (vapor phase volume fraction) α v =0.1 isosurface), near-field distribution of liquid phase (liquid phase volume fraction) α l =0.1 isosurface) The result is as follows Figure 7 As shown, the pressure distribution results are as follows: Figure 8 As shown, the volume fraction of vapor phase on the upper and lower walls of the nozzle ( α v The distribution results are as follows: Figure 9 As shown, the vapor condensation rate distribution on the upper and lower walls of the nozzle is as follows: Figure 10 As shown, in this invention, this value represents the injector nozzle cavitation risk index. E ero The nozzle outlet flow coefficient obtained from numerical simulation C d Liquid phase near-field diffusion angle Spray penetration distance P E and cavitation risk index E ero The performance indicators of the four injectors are shown in Table 2.
[0057]
[0058] Table 2
[0059] To achieve comparability of spray indices with different dimensions and directions on the same scale, this invention addresses { C d , , P E , E ero A unified normalization process is adopted. Quantiles are calculated for each indicator, and extreme value pinching is performed, converting the original values... x Crop to [ P 5, P 95[ ] interval, in order to reduce the impact of outliers on subsequent scale mapping.
[0060] In terms of directional setting, the physical meaning of the indicator will be used as a basis for... C d , and P E Consider it as a benefit-oriented (the higher the value, the better), and E ero Considered cost-based (lower values are better). Quantile Min-Max normalization is used for both benefit-based and cost-based indicators. Benefit-oriented approach:
[0061] Cost-based approach:
[0062] Taking the statistics of this batch of sample database as an example: C d : P 5 = 0.5 P 95 =0.99; : P 5 = 1° P 95 =60°; P E : P 5 = 1 P 95 =10; E ero : P 5 = 1 × 10 -4 , P 95 = 0.1.
[0063] The benefit-type indicators are as follows: = 0.3984; = 0.0556; = 0.6667.
[0064] Cost-related indicators are: = 0.9221.
[0065] The data processing module outputs a normalized index vector:
[0066] This invention relates to a 9-hole marine high-speed diesel engine injector. Actual cylinder bore and speed parameters indicate that this engine belongs to the small / medium bore high-speed engine category. In actual operation, this 9-hole marine high-speed diesel engine injector operates on ocean-going vessels, where cruising loads are high, fuel costs are sensitive, and thermal efficiency targets are high. Therefore, this embodiment defines the operating conditions as prioritizing economy and thermal efficiency. (Injector outlet flow coefficient) C d Liquid phase near-field diffusion angle Weight, spray penetration distance P E Weighting and cavitation risk index E ero The weighting selection is based on the combination of weighting parameters under the condition of prioritizing economy and thermal efficiency: [ w 1, w 2, w 3, w 4] = [0.25, 0.25, 0.25, 0.25].
[0067] The weight setting module outputs a weight vector:
[0068] The comprehensive evaluation module's scoring engine receives the normalized index vector output by the data processing module. and weight vector .
[0069] The scoring engine calculates the overall score:
[0070] The comprehensive evaluation module's decision engine bases decisions on the overall score. S The system is graded and its quality determined. In an implementation of a 9-hole marine high-speed diesel engine injector, the grading threshold is set as follows: Grade A (Excellent): S 80; Grade B (Good): 65 S 80; Grade C (Medium): 50 S 65; Grade D (Poor): S 50.
[0071] Based on the example classification, this embodiment is judged to be at level C (medium).
[0072] The comprehensive evaluation module's decision engine output report includes: Basic information: Sample number, engine model, fuel injector model, numerical simulation conditions and time; Specific data: Input indicator value { C d , , P E , E ero} = {0.6952, 4.28°, 7.786×10 -3 , 7}, Normalized index vector Weight vector ; Overall Score: S = 51.07; Nozzle rating: Class C (Medium); Optimization suggestion: When geometrically induced cavitation exists on the upper wall, it is recommended to increase the inlet fillet radius. r Or increase the nozzle taper K To weaken the geometric cavitation intensity of the upper wall, it is expected that... C d ↑、 E ero ↓; While ensuring penetration, appropriately increase the nozzle height. H h Alternatively, optimizing the nozzle length-to-diameter ratio could improve the axial kinetic energy / total kinetic energy ratio and enhance the near-field diffusion angle, which is expected to... θ ↑、 P E Stable or slightly increased; fine-tune needle valve lift within permissible response range. NL Increase the effective flow cross section to improve C d ,expected C d ↑.
[0073] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.
Claims
1. A multi-index comprehensive evaluation method for the injection performance of diesel engine injectors, characterized in that, Includes the following steps: S01. Data Acquisition: Obtain key spray parameters from the nozzle, including the nozzle outlet flow coefficient. C d Liquid phase near-field diffusion angle Spray penetration distance P E and cavitation risk index E ero ; S02. Data processing: Normalize the spray parameters so that indicators of different dimensions can be compared at the same latitude; S03. Weighting: Set the weights of each indicator according to the engine combustion conditions; S04. Comprehensive Scoring: Construct a comprehensive evaluation function to score the nozzle structure; S05. Comprehensive Decision: Determine the quality of the nozzle structure based on the comprehensive scoring results.
2. The multi-index comprehensive evaluation method for the injection performance of a diesel engine injector according to claim 1, characterized in that, The nozzle outlet flow coefficient C d Defined as: in, Q a This represents the actual mass flow rate at the nozzle exit. A out Where is the nozzle's outlet cross-sectional area. For liquid density, in incompressible flow, it can be considered as... It is a constant. P in This refers to fuel injection pressure. P out This is due to export pressure.
3. The multi-index comprehensive evaluation method for the injection performance of a diesel engine injector according to claim 1, characterized in that, The near-field diffusion angle of the liquid phase In the experiment, the spray boundary was identified by near-field images of the spray, and the angle between the two boundary lines formed by connecting the spray and the center of the nozzle outlet was calculated.
4. The multi-index comprehensive evaluation method for the injection performance of a diesel engine injector according to claim 1, characterized in that, The penetration distance of the spray-like phenomenon P E Defined as: in, AKE Let be the average axial kinetic energy of the fluid at the nozzle exit section. NAKE The average nonaxial kinetic energy, TKE For turbulent kinetic energy, ATE This represents the average nonaxial kinetic energy of the fluid at the nozzle exit section.
5. The multi-index comprehensive evaluation method for the injection performance of a diesel engine injector according to claim 1, characterized in that, The cavitation risk index E ero Based on the ZGB cavitation model of bubble dynamics, and combined with the integral value of the gas phase condensation rate near the nozzle wall at the wall surface, the gas phase condensation rate is calculated. R c Defined as: in, F cond The condensation coefficient is 0.
01. v This refers to the gas phase volume fraction. v The density is the gas phase density. R B The initial bubble radius is set to 0.001 mm. P For local flow field pressure, P v The saturated vapor pressure of the working medium (diesel). l ρ is the density of the liquid phase.
6. An evaluation system for implementing a multi-index comprehensive evaluation method for the injection performance of a diesel engine injector according to any one of claims 1-5, characterized in that, include: The system comprises a parameter acquisition module, a data processing module, a weight setting module, and a comprehensive evaluation module. The parameter acquisition module is used to acquire the near-field diffusion angle of the liquid phase, the spray-like penetration distance, the flow coefficient, and the cavitation risk index of the nozzle. The data processing module is used to normalize the spray parameters. The weight setting module is used to set the weights of each index according to the engine combustion conditions. The comprehensive evaluation module is used to score the nozzle structure based on a comprehensive evaluation function and output the results of the quality judgment.
7. The evaluation system for a multi-index comprehensive evaluation method of diesel engine injector injection performance according to claim 6, characterized in that, The parameter acquisition module includes an image acquisition unit and an image processing unit. The image acquisition unit is used to acquire near-field spray images of the nozzle based on the shadow method. The image processing unit is used to extract the spray boundary and calculate the near-field diffusion angle of the liquid phase through edge detection and morphological operations.
8. The evaluation system for a multi-index comprehensive evaluation method of diesel engine injector injection performance according to claim 6, characterized in that, The parameter acquisition module further includes a numerical simulation unit and a data interface unit. The numerical simulation unit is used to calculate the liquid volume fraction in the nozzle outlet back pressure chamber based on the built-in VOF model in ANSYS Fluent software. α l =0.1 isosurface to obtain the near-field diffusion angle of the spray. The axial kinetic energy and total kinetic energy of the nozzle exit cross section are used to obtain the spray-like penetration distance. P E And calculate the mass flow rate to obtain the flow coefficient. C d Cavitation risk index obtained based on ZGB cavitation model E ero The data interface unit is used to import raw data from an external test bench or simulation platform.
9. The evaluation system for a multi-index comprehensive evaluation method of diesel engine injector injection performance according to claim 6, characterized in that, The comprehensive evaluation module includes a scoring engine and a decision engine. The scoring engine calculates the comprehensive score based on normalized indicators and weights, while the decision engine classifies and judges the quality of the nozzle structure based on thresholds and generates a report that includes basic information, specific data, comprehensive score, nozzle level, and optimization suggestions.