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EGR valve effective flow area calculation method

A flow area, EGR valve technology, applied in the direction of calculation, computer-aided design, design optimization/simulation, etc., can solve the problems of increasing expansion work loss, inaccurate calculation of effective flow area, etc., to reduce the impact of turbulent flow, save money Development time, the effect of improving mesh accuracy

Pending Publication Date: 2021-11-12
DONGFENG CUMMINS ENGINE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The invention provides a method for calculating the effective flow area of ​​an EGR valve. By establishing a fluid domain model, adopting a grid division method, accurately and quickly simulating the flow characteristics of the EGR valve, and calculating the effective flow area of ​​the EGR valve based on the total-total pressure difference, the effective characterization The flow characteristics of the EGR valve on the engine solve the existing technical problems such as increasing the loss of expansion work by using the static-static pressure difference calculation method, which leads to inaccurate calculation of the effective flow area

Method used

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  • EGR valve effective flow area calculation method

Examples

Experimental program
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Embodiment 1

[0053] like figure 1 — image 3 As shown, a method for calculating the effective flow area of ​​an EGR valve specifically includes the following steps:

[0054] S01: Establish the fluid domain model under the maximum effective opening of the EGR valve, and set the opening of the EGR valve to 80% of the maximum nominal opening;

[0055] S02: Perform structural processing on the fluid domain model in step S01, the specific method is: 1) remove the narrow and small structures that do not affect the calculation;

[0056] 2) The extension length L1 of the inlet section of the EGR valve is 2-4 times the equivalent diameter of the valve inlet wet circumference;

[0057] 3) The extension length L2 of the outlet section of the EGR valve is 4-6 times the equivalent diameter of the wet circumference of the valve outlet;

[0058] S03: Preprocessing the fluid domain model in step S02;

[0059] S04: Perform fluid analysis on the fluid domain model in step S03, and calculate flow and pre...

Embodiment 2

[0064] On the basis of Embodiment 1, the preprocessing method of the fluid domain model in the step S02 is:

[0065] 1) Set the inlet and outlet boundary name marks at the inlet and outlet positions of the EGR valve flow channel respectively;

[0066] 2) Divide the fluid domain grid with a grid size of 3-6 mm; the fluid domain grid of the EGR valve body is a mixed grid with a size of 1-2 mm; the first layer grid size of the boundary layer is 0.2-0.4 mm, The number of layers is ≥6, and the growth rate of the boundary layer grid is 1.05-1.08; the number of grids between the valve and the valve seat is ≥6 layers.

[0067] This example figure 2 As shown, the inlet position of the EGR valve flow channel is the EGR valve inlet 3, and the outlet position of the EGR valve flow channel is the EGR valve outlet 5.

[0068] The import and export boundaries are respectively as follows figure 2 The inlet boundary 6 and the outlet boundary 7 are shown.

Embodiment 3

[0070] On the basis of the foregoing embodiments, the fluid analysis method for the fluid domain model in the S03 step is:

[0071] 1) Set the boundary of the fluid domain as the pressure boundary, where the inlet boundary is the total pressure with a size of 6000Pa, the outlet boundary is the static pressure with a size of 0Pa, and the pressures are all relative pressures;

[0072] 2) The fluid is set as a compressible fluid, the initial temperature is 25°C, the Realizableκ-εturbulence model is selected, and the wall function is Scalable Wall;

[0073] 3) The minimum number of calculation steps is 1000, monitor the change of the outlet flow, and the flow oscillation deviation is ≤0.5%; if the flow oscillation deviation is >0.5%, adjust the relaxation factor and recalculate.

[0074] 4) After the calculation is completed, read the total pressure P at the inlet of the EGR valve in_EGR , The total pressure P at the outlet of the EGR valve out_EGR, , EGR valve outlet density ρ_...

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Abstract

The invention discloses an EGR valve effective flow area calculation method. The calculation method comprises the following steps: S01, building a fluid domain model under the maximum effective opening degree of the EGR valve; s02, performing structure processing on the fluid domain model in the step S01; s03, preprocessing the fluid domain model in the step S02; s04, performing fluid analysis on the fluid domain model in the step S03, and obtaining flow and pressure numerical values through calculation; s05, calculating the effective flow area according to the flow and pressure values obtained in the step S04; s06, judging whether the effective circulation area obtained in the step S05 meets the use requirement or not; according to the technical scheme, a total-total pressure difference calculation method is adopted, and the calculation result can be more practical. In practical application, the outlet pressure is not rapidly expanded, so that the effective flow area curve of the EGR valve, which is calculated by considering the influence of the dynamic pressure, can be better applied to performance evaluation. The invention can be applied to the initial stage of engine development, effectively saves the development time, and is higher in accuracy.

Description

technical field [0001] The invention relates to the field of calculation and selection of an EGR valve for a diesel engine, in particular to a calculation method for an effective flow area of ​​an EGR valve. Background technique [0002] At present, diesel engines are facing the consideration of upgrading emission regulations, and the EGR route has been selected to varying degrees in both the National VI for vehicle use and the National IV for non-vehicle use. In the development of EGR system, the reasonable selection of EGR valve is very important. In order to select a suitable EGR valve, it is necessary to calculate the effective flow area of ​​the EGR valve. [0003] In the development of EGR valves, the test method is usually used to evaluate the flow area of ​​the valve, but this method needs to be carried out after the sample design is completed, which usually cannot meet the needs in the development stage, and it takes a lot of time for the layout and sample of the t...

Claims

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Application Information

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IPC IPC(8): G06F30/28G06F113/08G06F119/14
CPCG06F30/28G06F2113/08G06F2119/14
Inventor 程建德龚作伟王勇
Owner DONGFENG CUMMINS ENGINE
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