Multi-stage supercharged multi-cylinder diesel engine air inlet pipeline and air inlet system optimization design method based on minimum entropy production analysis

Abstract

The invention provides a multi-stage supercharged multi-cylinder diesel engine air inlet pipeline and air inlet system optimization design method based on minimum entropy production analysis, and belongs to the technical field of diesel engines. The problem that an existing diesel engine air inlet pipeline and air inlet system design method is low in efficiency is solved. According to the method, diesel engine computational fluid mechanics simulation analysis and a thermodynamic entropy increase theory are combined, the influence of pipeline wall surface heat insulation, thermal entropy flow zero and pipe wall heat transfer on steady-state flow entropy change is isolated, energy entropy production of an air inlet steady-state flow pipeline is obtained, and quantitative analysis of entropy production is provided for pipeline flow resistance analysis; the transient flow is replaced by the average flow of the single cylinder of the intake manifold, so that the energy entropy production in the flowing process of the intake manifold flowing into each cylinder can be quantified, and quantifiable entropy production analysis is provided for transient pipeline flowing; the method is applied to optimization design of the air inlet pipeline of the diesel engine.

Description

Technical Field

[0001] The present application relates to the technical field of diesel engines, and in particular to a method for optimizing the design of an intake pipe and an intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis. Background Art

[0002] Multi-cylinder diesel engines use multi-stage turbocharging and intercooling technology to increase intake pressure and reduce air temperature. The intake system piping connecting the multi-stage turbocharger and intercooler is complex in shape and structure, containing numerous flow resistance components such as elbows, reducers, and the intake manifold. Existing fluid mechanics hydraulic loss methods involve both longitudinal and local resistance, and the longitudinal and local resistance coefficients vary with flow conditions, thus exhibiting uncertainty. Currently, the design of multi-stage turbocharged diesel engine intake ducts is largely empirical. Due to design and structural limitations, significant flow energy losses occur within the intake duct, increasing the total flow energy loss of a multi-stage turbocharged and intercooled intake system comprised of multiple pipes.

[0003] However, in terms of intake pipe and intake system design, there is still a lack of systematic and efficient diesel engine intake pipe and system optimization design methods. Summary of the Invention

[0004] In order to solve the above technical problems, the present application proposes a method for optimizing the design of the intake pipe and intake system of a multi-stage turbocharged multi-cylinder diesel engine based on minimum entropy production analysis.

[0005] The technical solution adopted in this application is: a method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis, comprising the following steps:

[0006] Step 1: Given an initial intake pipe system plan for a multi-stage turbocharged multi-cylinder diesel engine, determine the basic geometric parameters of each pipe. The intake pipe system includes every pipe in the intake system, namely, the steady-state intake pipe consisting of each intake pipe branch and the intake manifold, and the transient-state intake manifold.

[0007] Step 2: In any engine performance simulation and analysis software, a one-dimensional diesel engine performance model is constructed, and a one-dimensional fluid domain flow calculation model of the entire diesel engine is established;

[0008] Step 3: Set the pipe wall to be adiabatic in the simulation flow analysis to make the thermal entropy flow zero;

[0009] Step 4, determining the operating condition of the maximum flow resistance of the intake pipe system and the corresponding mass flow rate;

[0010] Step 5: Under the working condition of maximum flow resistance, perform steady-state simulation on each pipeline in the steady-state flow intake pipeline, obtain the inlet parameters and outlet parameters of each pipeline based on the simulation results, calculate the steady-state flow energy entropy change of each pipeline separately, and calculate the total entropy generation of the intake pipeline in the steady state;

[0011] Step 6: Construct an intake manifold model, import the intake manifold model into the same engine performance simulation calculation software, establish a fluid domain flow calculation model of the transient flow intake manifold, perform steady-state flow simulation from the intake manifold inlet to each individual cylinder, set the pipeline wall to be thermally insulated to make the thermal entropy flow zero, and then perform steady-state flow simulation from the intake manifold to each other cylinder separately. Use the average flow calculation method to calculate the flow entropy generation of the intake manifold, calculate the entropy generation of each cylinder separately, and then average the entropy generation of multiple cylinders to obtain the average entropy generation of the multi-cylinder intake manifold flow.

[0012] Step 7, calculating the total entropy production of the intake pipe system;

[0013] Step 8: By changing the basic geometric parameters of each pipeline in the initial intake pipeline system scheme, different intake pipeline system schemes are obtained. Repeat steps 1 to 7 to obtain the entropy production of the changed scheme, compare it with the initial scheme, and take the intake pipeline scheme with the minimum entropy production as the final optimized scheme.

[0014] Furthermore, the steady-state flow intake pipeline includes: the pipeline from the filter to the low-pressure stage compressor, the pipeline from the low-pressure stage compressor to the interstage intercooler, the pipeline between the interstage intercooler and the high-pressure stage compressor, the pipeline between the high-pressure stage compressor and the high-pressure intercooler, and the intake manifold between the high-pressure intercooler and the intake manifold.

[0015] Furthermore, the basic geometric parameters of the pipeline include pipeline material, pipe length, pipe diameter, elbow bending radius and bending angle, bifurcated pipe diameter and bifurcated pipe centerline geometric position dimensions. The basic geometric parameters of the pipeline are determined by first discretizing each pipeline into basic straight pipe sections, curved pipe sections, variable diameter sections, bifurcated pipes and combinations of these.

[0016] Furthermore, the steps for building a one-dimensional diesel engine performance model are as follows:

[0017] The intake pipe is built according to the actual flow sequence and structure to obtain a one-dimensional model of the diesel engine intake system. The basic geometric parameters of the pipe are input to establish a complete one-dimensional diesel engine performance model.

[0018] Furthermore, the operating condition of the maximum flow resistance of the intake pipe is the engine rated power operating condition.

[0019] Furthermore, the inlet and outlet parameters of each pipeline are obtained based on the simulation results, where the inlet parameters include the inlet pressure and inlet temperature , outlet parameters include outlet pressure and outlet temperature .

[0020] Furthermore, the entropy change calculation formula is as follows:

[0021] ;

[0022] Where: is the gas constant, is the constant pressure specific heat constant;

[0023] Steady-state adiabatic pipeline entropy generation ;

[0024] Total entropy generation of the intake pipe in steady-state adiabatic ; i is a different pipeline.

[0025] Furthermore, the steps for calculating the flow entropy production of the intake manifold using the average flow calculation method are as follows: set the steady-state flow of the intake manifold to a certain value, adjust the outlet pressure so that the inlet pressure result is the same as the inlet pressure of the one-dimensional flow simulation result in step 5, and the average flow calculation formula is as follows:

[0026] Single cylinder displacement: ;

[0027] Corresponding quality: ;

[0028] Intake time: ;

[0029] Average mass flow rate: ;

[0030] Where: is the cylinder diameter, For stroke, is the gas constant, is the intake pressure, is the intake air temperature, is the rated speed;

[0031] The inlet and outlet pressures are obtained by adiabatic steady flow simulation calculation of the intake manifold 、 and inlet and outlet temperatures 、 , according to the calculation formula in step 5, the entropy production of a single cylinder is obtained;

[0032] Repeat the above steps for each cylinder of a multi-cylinder diesel engine and calculate the entropy production of each cylinder;

[0033] Flow average entropy generation of multi-cylinder intake manifold , j corresponds to each cylinder.

[0034] Furthermore, the total entropy generation of the intake pipe system .

[0035] Furthermore, when performing steady-state flow simulation from the intake manifold inlet to each individual cylinder, the intake manifold outlets of the cylinders other than the cylinder to be simulated need to be blocked.

[0036] The beneficial effects of this application compared to the prior art are:

[0037] (1) This application combines the computational fluid dynamics simulation analysis of diesel engines with the thermodynamic entropy increase theory, and through the insulation of the pipeline wall, makes the thermal entropy flow zero, isolates the influence of the heat transfer of the pipeline wall on the entropy change of the steady-state flow, and obtains the energy entropy production of the intake steady-state flow pipeline, providing a quantitative analysis from the perspective of entropy production for the pipeline flow resistance analysis.

[0038] (2) This application combines the steady-state flow simulation analysis of the diesel engine intake manifold with the thermodynamic entropy increase theory, isolates the influence of the thermal entropy flow on the flow entropy change by thermally isolating the pipeline wall, and replaces the transient flow with the average flow of a single cylinder of the intake manifold, thereby quantifying the energy entropy generation of the flow process of the intake manifold into each cylinder, and providing a quantifiable entropy generation analysis for the transient pipeline flow.

[0039] (3) This application provides another evaluation metric for evaluating the multi-cylinder consistency of intake manifold design by quantifying the entropy generated by the intake manifold flowing to each cylinder. The multi-cylinder average entropy generation is used to quantify the flow process losses distributed by the intake manifold to each cylinder.

[0040] (4) This application obtains the total flow loss of the intake system by summing the entropy generation of the intake pipe and the average entropy generation of the intake manifold. This loss is defined by the total entropy generation. The smaller the entropy generation, the less flow energy loss, the smaller the resistance, and the higher the efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present application will be further described below with reference to the accompanying drawings:

[0042] Figure 1 This is a flow chart of the design method of the intake pipe and intake system of a multi-stage turbocharged multi-cylinder diesel engine based on minimum entropy production analysis.

[0043] Figure 2 This is a one-dimensional diesel engine performance model diagram provided in an embodiment of the present application.

[0044] Figure 3 This is a one-dimensional steady-state flow CFD model diagram of the left cylinder intake manifold provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] like Figures 1 to 3 As shown, the embodiment of the present application provides a method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis, comprising the following steps:

[0046] Step 1: Consider an intake piping system solution, including each pipe in the intake system—the steady-state intake pipe and the transient intake manifold. Specifically, the pipe from the filter to the low-pressure compressor, the pipe from the low-pressure compressor to the interstage intercooler, the pipe from the interstage intercooler to the high-pressure compressor, the pipe from the high-pressure compressor to the high-pressure intercooler, the intake manifold from the high-pressure intercooler to the intake manifold, and the intake manifold. Each pipe is discretized into basic straight sections, curved sections, variable diameter sections, bifurcated sections, and combinations of these. The basic geometric parameters of each pipe section are then determined, including pipe material, length, diameter, bend radius and angle, bifurcated pipe diameter, and bifurcated pipe centerline geometry.

[0047] Step 2: Build the intake pipe according to the actual flow sequence and structure to obtain a one-dimensional model of the diesel engine intake system, and input the above pipe parameters to establish a complete one-dimensional diesel engine performance model.

[0048] Step 3: Due to the existence of temperature difference, any actual pipeline will have heat transfer. The only effect of wall heat transfer on the open system is temperature, and pressure is not affected by temperature. In order to isolate the influence of heat transfer thermal entropy flow on energy dissipation entropy change, only through simulation flow analysis can the pipeline wall be set to be adiabatic to make the thermal entropy flow zero, so that the pipeline flow only has entropy production caused by flow energy dissipation.

[0049] Step 4: Determine the operating condition of the maximum flow resistance of the intake pipe system and the corresponding mass flow rate, which is generally the rated power condition of the engine, and perform one-dimensional flow calculation of the engine.

[0050] Step 5: For each pipeline before the intake manifold, when the flow in the pipeline is in a high Reynolds number turbulent stable flow state under rated working conditions, the inlet parameters of each pipeline (including inlet pressure and inlet temperature ) and outlet parameters (including outlet pressure and outlet temperature ), calculate the steady-state flow energy entropy change of each pipeline separately.

[0051] In the flow of diesel engine intake pipe, air is regarded as an ideal gas, and the process adiabatic index is , is the constant pressure specific heat constant, and the entropy change calculation formula is as follows:

[0052] ;

[0053] Where: The gas constant is 287 J / (kg·K).

[0054] Steady-state adiabatic pipeline entropy generation . is the entropy of the export, is the entropy at the inlet. Since the entropy generation of an adiabatic pipeline can only be greater than zero and be positive, the pipeline with the smallest entropy generation represents the least flow energy loss.

[0055] Total entropy generation of a steady-state piping system ; i is a different intake pipe.

[0056] Step 6: Analyze the flow resistance and entropy generation of the intake manifold. Since each cylinder only has intake flow entering the cylinder during the intake stroke, the intake manifold distributes the steady-state flow pulsation of the intake manifold to each cylinder. The calculation of entropy generation is only applicable to steady-state flow and not to transient flow calculations. Therefore, the average flow calculation method is used to calculate the flow entropy generation of the intake manifold. For the intake manifold, a flow analysis model is also established. The wall is adiabatically isolates the thermal entropy flow. The steady-state flow analysis separately enters each cylinder and the corresponding entropy generation. Import the intake manifold model into any CFD calculation software, such as FLUENT, CFX, FIRE, CONVERGE or GT-SUITE, establish a fluid domain flow calculation model, and perform steady-state flow simulation from the intake manifold inlet to each individual cylinder. The manifold inlet diameter of each cylinder of the diesel engine is equal to the connecting pipe in front. This can reduce the boundary entropy generation of the two pipes. The manifold outlet is equal to the intake duct on the cylinder head to avoid boundary entropy generation. The pipe wall is set to be insulated to make the thermal entropy flow zero. The steady-state flow of the intake manifold is set to a certain value, and the outlet pressure is adjusted so that the inlet pressure result is the same as the inlet pressure of the one-dimensional flow simulation result in step 5. The average flow calculation formula is as follows:

[0057] Single cylinder displacement: ;

[0058] Corresponding quality: ;

[0059] Intake time: ;

[0060] Average mass flow rate: ;

[0061] Where: is the cylinder diameter, For stroke, The gas constant is 287 J / (kg·K), is the intake pressure, is the intake air temperature, is the rated speed; the inlet and outlet pressures are obtained by adiabatic steady flow simulation calculation of the intake manifold 、 and inlet and outlet temperatures 、 , according to the calculation formula in step 5, the entropy production of a single cylinder is obtained.

[0062] Repeat the above steps for each cylinder of the multi-cylinder diesel engine and calculate the entropy production of each cylinder.

[0063] Flow average entropy generation of multi-cylinder intake manifold , j corresponds to each cylinder.

[0064] Step 7: The total entropy generation of the intake pipe system .

[0065] Step 8: Change to a different intake pipe system solution. Modify various pipe parameters, such as pipe diameter, turning radius, and bifurcated pipe angles, and repeat steps 1 through 7. First, calculate the entropy generation of the steady-state intake pipe. Then calculate the entropy generation from the intake manifold to each cylinder, and then calculate the average entropy generation from the intake manifold to each cylinder. Finally, add these together to obtain the entropy generation of this intake pipe system solution. Compared with the entropy generation of solution 1, the intake pipe solution with the lowest entropy generation has the lowest flow energy loss, lowest flow resistance, and lowest degree of irreversibility.

[0066] The embodiment of the present application implements an optimized design method for an intake pipe and an intake system according to two specific pipe design schemes, including the following steps:

[0067] Step 1, determine the intake pipe system scheme 1, including each pipe in the intake system, including the pipe from the filter to the front of the low-pressure stage compressor, the pipe from the low-pressure stage compressor to the interstage intercooler, the pipe between the interstage intercooler and the high-pressure stage compressor, the pipe between the high-pressure stage compressor and the high-pressure intercooler, the intake main pipe between the high-pressure intercooler and the intake manifold, and the intake manifold.

[0068] The intake pipe positions and related basic geometric parameters corresponding to the existing scheme 1 are shown in Table 1. The basic geometric parameters of each pipe include pipe material, pipe length, pipe diameter, elbow radius and bending angle, bifurcated pipe diameter, and bifurcated pipe centerline geometric dimensions.

[0069]

[0070] Table 1 Piping parameters of Scheme 1.

[0071] Step 2: Build a one-dimensional model of the diesel engine intake system according to the actual flow sequence and structure of the intake pipe, and establish a complete one-dimensional diesel engine performance model; this implementation uses GT-SUITE software to build the model, and the built one-dimensional model of the diesel engine intake system is as follows: Figure 2 As shown in the figure, the yellow areas with different labels represent different pipeline positions in step 1.

[0072] Step 3: Set all intake pipe walls in the model to be adiabatic so that the thermal entropy flow is zero, so that only entropy is generated during the pipe flow process.

[0073] Step 4: Determine the operating condition of the maximum flow resistance of the intake pipe system and the corresponding mass flow rate, which is generally the rated power condition of the engine, and perform one-dimensional flow calculation of the engine;

[0074] Assume that the rated operating speed of the engine is 3200r / min and the flow rate is 1.248kg / s.

[0075] Step 5: For each steady-state flow intake pipe (steady flow pipe) before the intake manifold, the flow in the pipe is in a high Reynolds number turbulent stable flow state under rated working conditions. According to the simulation results, the inlet parameters of each pipe (including inlet pressure and inlet temperature ) and outlet parameters (including outlet pressure and outlet temperature ), calculate the entropy generation of each steady flow pipeline separately, and the entropy generation of the steady flow pipeline The calculation process and results are shown in Table 2.

[0076]

[0077] Table 2 Calculation process of steady-state pipeline entropy production for Scheme 1.

[0078] Pipeline 6 is a bifurcated main pipe before the intake manifold, supplying air to the left and right banks of cylinders respectively. It also has a stable flow, with an average entropy production of 0.0515 J / K.

[0079] Total entropy generation of the intake duct in steady-state flow =0.8369J / K.

[0080] Step 6: Analyze the flow resistance and entropy generation of the intake manifold.

[0081] Since the diesel engine of this embodiment is a V-type 8-cylinder engine, it has two left and right cylinder banks, and each cylinder bank has a corresponding independent intake manifold.

[0082] Under steady-state flow from the left cylinder intake manifold inlet to each individual cylinder, the single-cylinder average flow calculation formula is as follows:

[0083] Single cylinder displacement: ;

[0084] Corresponding quality: ;

[0085] Intake time: ;

[0086] Average mass flow rate per cylinder: .

[0087] Then, for the intake manifold of the left cylinder bank, a GT steady-state flow analysis model is established to simulate the steady-state flow from the inlet of the left cylinder bank intake manifold to each individual cylinder. Figure 3 When calculating the entropy production of the steady flow of cylinder 1, the intake manifold outlets of cylinders 2, 3, and 4 are sealed with end caps, and the wall insulation is set to isolate the heat entropy flow. The steady-state flow analysis is carried out to analyze the flow resistance and corresponding entropy production of each cylinder separately. The steady-state flow rate of the left cylinder intake manifold inlet is set to When the manifold outlet pressure is adjusted to 5.487 bar, the manifold inlet pressure is 5.589 bar, which is the same as the one-dimensional flow simulation result in step 5. Then calculate the steady-state entropy production of cylinders 2, 3, and 4 respectively, and adjust the static pressure of each manifold outlet leading to the cylinder so that the steady-state flow rate is equal to the average flow rate of this cylinder. The calculated pressure and temperature are shown in Tables 3 and 4 below.

[0088]

[0089] Table 3. Single-cylinder steady-flow entropy generation of the left-bank intake manifold and average entropy generation of the left-bank intake manifold for Scheme 1.

[0090]

[0091] Table 4. Single-cylinder steady-flow entropy generation of the right-bank intake manifold and average entropy generation of the left-bank intake manifold for Scheme 1.

[0092] It can be seen from the above two tables that the structural parameters of the left and right cylinder intake manifolds are symmetrical and the same. Under the same steady-state flow rate, the resulting resistance entropy production is also the same, and the average entropy production of the intake manifold is also the same.

[0093] Step 7: The total entropy generation of the intake pipe system =0.8369+3.3630=4.1999 J / K.

[0094] Step 8: Adjust parameters to compare the entropy production of different schemes. Design Scheme 2, an intake pipe system with different structural parameters. Its structural parameters are shown in Table 5. Scheme 2 differs from Scheme 1 in that the diameter of the pipe in front of the low-pressure compressor is increased, the diameter of the main bifurcation pipe in the high-pressure intercooler -> main bifurcation pipe section is reduced, and the inlet diameter of the main bifurcation pipe is reduced.

[0095]

[0096] Table 5 Piping parameters of Scheme 2.

[0097] The calculation process table of the steady-state pipeline entropy production of Scheme 2 is shown in Table 6 below, and the table of the single-cylinder steady flow entropy production of the left cylinder intake manifold and the average entropy production of the left cylinder intake manifold of Scheme 2 is shown in Table 7 below.

[0098]

[0099] Table 6 Calculation process of entropy generation in steady-state pipeline of Scheme 2;

[0100]

[0101] Table 7 Single-cylinder steady-flow entropy production of the left-bank intake manifold and average entropy production of the left-bank intake manifold for Scheme 2.

[0102] The total entropy generation of the intake system in Scheme 2 =0.7495+2.9033=3.6528 J / K.

[0103] Compared with Scheme 1, the entropy generation of Scheme 2 is less than that of Scheme 1, so Scheme 2 has smaller flow resistance and lower flow energy dissipation, and is a better intake pipe and system solution.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis, characterized by: The following steps are involved: Step 1: Given an initial intake pipe system plan for a multi-stage turbocharged multi-cylinder diesel engine, determine the basic geometric parameters of each pipe. The intake pipe system includes every pipe in the intake system, namely, the steady-state intake pipe consisting of each intake pipe branch and the intake manifold, and the transient-state intake manifold. Step 2: In any engine performance simulation and analysis software, a one-dimensional diesel engine performance model is constructed, and a one-dimensional fluid domain flow calculation model of the entire diesel engine is established; Step 3: Set the pipe wall to be adiabatic in the simulation flow analysis to make the thermal entropy flow zero; Step 4, determining the operating condition of the maximum flow resistance of the intake pipe system and the corresponding mass flow rate; Step 5: Under the working condition of maximum flow resistance, perform steady-state simulation on each pipeline in the steady-state flow intake pipeline, obtain the inlet parameters and outlet parameters of each pipeline based on the simulation results, calculate the steady-state flow energy entropy change of each pipeline separately, and calculate the total entropy generation of the intake pipeline in the steady state; Step 6: Construct an intake manifold model, import the intake manifold model into the same engine performance simulation calculation software, establish a fluid domain flow calculation model of the transient flow intake manifold, perform steady-state flow simulation from the intake manifold inlet to each individual cylinder, set the pipeline wall to be thermally insulated to make the thermal entropy flow zero, and then perform steady-state flow simulation from the intake manifold to each other cylinder separately. Use the average flow calculation method to calculate the flow entropy generation of the intake manifold, calculate the entropy generation of each cylinder separately, and then average the entropy generation of multiple cylinders to obtain the average entropy generation of the multi-cylinder intake manifold flow. Step 7, calculating the total entropy production of the intake pipe system; Step 8: By changing the basic geometric parameters of each pipeline in the initial intake pipeline system scheme, different intake pipeline system schemes are obtained. Repeat steps 1 to 7 to obtain the entropy production of the changed scheme, compare it with the initial scheme, and take the intake pipeline scheme with the minimum entropy production as the final optimized scheme.

2. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 1, characterized in that: The steady-state flow intake pipe includes: the pipe from the filter to the low-pressure stage compressor, the pipe from the low-pressure stage compressor to the interstage intercooler, the pipe between the interstage intercooler and the high-pressure stage compressor, the pipe between the high-pressure stage compressor and the high-pressure intercooler, and the intake manifold between the high-pressure intercooler and the intake manifold.

3. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 1, characterized in that: The basic geometric parameters of the pipeline include pipe material, pipe length, pipe diameter, elbow bending radius and bending angle, bifurcated pipe diameter and bifurcated pipe centerline geometric position dimensions. The basic geometric parameters of the pipeline are determined by first discretizing each pipeline into basic straight pipe sections, curved pipe sections, variable diameter sections, bifurcated pipes and combinations of these.

4. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 1, characterized in that: The steps to build a one-dimensional diesel engine performance model are as follows: The intake pipe is built according to the actual flow sequence and structure to obtain a one-dimensional model of the diesel engine intake system. The basic geometric parameters of the pipe are input to establish a complete one-dimensional diesel engine performance model.

5. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 1, characterized in that: The operating condition of the maximum flow resistance of the intake pipe is the engine rated power condition.

6. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 1, characterized in that: According to the simulation results, the inlet parameters and outlet parameters of each pipeline are obtained, where the inlet parameters include the inlet pressure and inlet temperature , outlet parameters include outlet pressure and outlet temperature .

7. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 6, characterized in that: The entropy change calculation formula is as follows: ； Where: is the gas constant, is the constant pressure specific heat constant; Steady-state adiabatic pipeline entropy generation ; Total entropy generation of the intake pipe in steady-state adiabatic ; i is a different pipeline.

8. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 7, characterized in that: The steps for calculating the flow entropy production of the intake manifold using the average flow calculation method are as follows: set the steady-state flow of the intake manifold to a certain value, adjust the outlet pressure so that the inlet pressure result is the same as the inlet pressure of the one-dimensional flow simulation result in step 5, and the average flow calculation formula is as follows: Single cylinder displacement: ; Corresponding quality: ; Intake time: ; Average mass flow rate: ; Where: is the cylinder diameter, For stroke, is the gas constant, is the intake pressure, is the intake air temperature, is the rated speed; The inlet and outlet pressures are obtained by adiabatic steady flow simulation calculation of the intake manifold 、 and inlet and outlet temperatures 、 , according to the calculation formula in step 5, the entropy production of a single cylinder is obtained; Repeat the above steps for each cylinder of a multi-cylinder diesel engine and calculate the entropy production of each cylinder; Flow average entropy generation of multi-cylinder intake manifold , j corresponds to each cylinder.

9. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 8, characterized in that: Total entropy generation of the intake manifold system .

10. The method for optimizing the design of the intake pipe and intake system of a multi-stage supercharged multi-cylinder diesel engine based on minimum entropy production analysis according to claim 1, characterized in that: When performing steady-state flow simulation from the intake manifold inlet to each individual cylinder, the intake manifold outlets of the cylinders other than the cylinder to be simulated need to be blocked.

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