CN117236212A - Method and device for determining design parameters of piston - Google Patents

Abstract

The application provides a method and a device for determining design parameters of a piston, wherein after a combustion chamber simulation model of a gas engine is constructed and gas combustion simulation is carried out, a pressure change curve of each test point at the top of the piston in the simulation process is obtained; determining a knock evaluation value of the gas engine based on the pressure change curve of the test point; if the knocking evaluation value exceeding the set threshold range exists, adjusting the ignition advance angle of the combustion chamber simulation model, and carrying out gas combustion simulation again; if the knocking evaluation value exceeding the set threshold value range does not exist, obtaining an average turbulence energy ratio value in gas combustion simulation, and obtaining a change chart of an average gas flow speed and a target temperature isosurface in the set range of the spark plug model; the target design parameters of the piston in the gas engine are determined based on the average turbulence ratio, the average gas flow velocity, and a graph of the target temperature isosurface. The scheme of the application can reasonably determine the proper design parameters of the piston.

Description

Method and device for determining design parameters of piston

Technical Field

The application relates to the technical field of computer simulation, in particular to a method and a device for determining design parameters of a piston.

Background

In order to alleviate energy crisis and environmental pollution, natural gas engines capable of reducing gas consumption and emission have been widely used in various vehicles.

Currently, most gas engines essentially follow the structure of diesel engines. The diesel engine is matched with the porous fuel injector and the step combustion chamber, and adopts a vortex air inlet system, but the gas engine is used as a premixed combustion system, and the gas combustion in the cylinder mainly depends on the speed at the spark plug and the turbulence energy in the cylinder, which is the disadvantage of the vortex air inlet system. Moreover, the overall flow intensity of the vortex air inlet system is low, and the circular variation of each cylinder of the gas engine is easy to be large.

In order to improve the gas combustion effect in the gas engine and reduce the cycle variation, the gas engine is started to employ a tumble combustion system, and in this case, components such as a piston and a cylinder head related to a combustion chamber system in the gas engine also need to be adaptively adjusted. The design parameters related to the piston design process in the gas engine are more, but the unreasonable design parameters may affect the gas combustion effect in the gas engine cylinder, so how to more reasonably determine the design parameters of the piston is a technical problem to be solved by those skilled in the art.

Disclosure of Invention

In view of this, the present application provides a method and apparatus for determining design parameters of a piston to achieve a more rational determination of design parameters of a piston in a gas engine.

To achieve the above object, in one aspect, the present application provides a method for determining a design parameter of a piston, including:

based on the mechanical structure and initial design parameters of a piston of the gas engine, constructing a combustion chamber simulation model of the gas engine, wherein the combustion chamber simulation model at least comprises a simulated piston model and a simulated spark plug model;

performing gas combustion simulation by using the combustion chamber simulation model, and obtaining pressure values of all test points in the top of a piston of the piston model at different moments to obtain a pressure change curve of each test point;

determining a knock evaluation value of the gas engine based on the pressure change curve of the test point;

if the knocking evaluation value exceeding the set threshold range exists, adjusting the ignition advance angle corresponding to the combustion chamber simulation model, and returning to execute the operation of performing gas combustion simulation by using the combustion chamber simulation model based on the adjusted ignition advance angle;

If the knocking evaluation value exceeding the set threshold value range does not exist, obtaining an average turbulence energy ratio in the combustion chamber simulation model in the gas combustion simulation process, an average gas flow speed in the spark plug model set range and a change chart of a target temperature equivalent surface in the combustion chamber simulation model, wherein the average turbulence energy ratio is a ratio of average turbulence energy of an air inlet side and average turbulence energy of an air outlet side of the combustion chamber simulation model, and the target temperature equivalent surface is a temperature equivalent surface with a temperature being a target temperature value;

and determining target design parameters of pistons in the gas engine based on the average turbulence energy ratio, the average gas flow speed and a change chart of target temperature isosurface.

In one possible implementation, the determining the target design parameter of the piston in the gas engine based on the average turbulence ratio, the average flow velocity of the gas, and the change map of the target temperature isosurface includes:

outputting a change chart of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface;

if the design parameter adjustment value of the piston input by the user is obtained, adjusting the simulated piston model based on the design parameter adjustment value, and returning to execute the operation of performing gas combustion simulation by using the combustion chamber simulation model;

And if the simulation completion instruction input by the user is obtained, taking the design parameter adopted by the last simulation of the piston model as the target design parameter of the piston in the gas engine.

In yet another possible implementation, the piston includes a combustion chamber pocket, a piston top surface surrounding a circumference of the combustion chamber pocket, and a transition slope connecting the piston top surface and the piston side, wherein the piston top surface is an annular planar surface and the piston top surface is higher than the piston side surface;

the bottom center of the combustion chamber pit is provided with a bottom bulge part extending towards the opening of the combustion chamber pit;

the surface of the combustion chamber pit is a combination of a part of a spherical surface and the surface of the bottom bulge part, and the spherical surface part in the combustion chamber pit is in smooth transition connection with the surface of the bottom bulge part.

In yet another possible implementation, if the average turbulence energy ratio is not greater than a set ratio, the user-entered design parameter adjustment value for the piston includes: the method comprises the steps of adjusting a value corresponding to the radius of the projection of the axis of the bottom bulge part in the combustion chamber pit on a horizontal plane, and adjusting the central line offset of the combustion chamber pit, wherein the central line offset is the offset of the central line of the combustion chamber pit relative to the central line of the piston, and the central line of the combustion chamber pit is not overlapped with the central line of the piston;

If the average flow velocity of the gas is not greater than a set velocity value, the user-entered design parameter adjustment values for the piston include: a depth adjustment value of the maximum depth of the combustion chamber pit and a radius adjustment value of a spherical radius corresponding to the spherical surface in the combustion chamber pit;

if the change graph of the target temperature isosurface shows that flame surface propagation is uneven in a combustion chamber simulation model, the design parameter adjustment value of the piston input by the user comprises: the length adjustment value of the projection line of the intersection line of the transition inclined plane and the plane passing through the center line of the piston in the horizontal plane, and the angle adjustment value of the included angle between the intersection line of the transition inclined plane and the plane passing through the center line of the piston and the projection line.

In yet another possible implementation, the average turbulence energy ratio is not greater than a set ratio, including: the average turbulence energy ratio is not greater than 1.2;

the average flow rate of the gas not greater than a set rate value includes: the average flow velocity of the gas is not more than 20 m/s.

In still another possible implementation manner, the adjusting the ignition advance angle corresponding to the combustion chamber simulation model if there is a knock evaluation value exceeding a set threshold range includes:

If the knock evaluation value exceeds a set threshold range and is smaller than the minimum boundary value in the set threshold range, increasing the ignition advance angle corresponding to the combustion chamber simulation model by a target angle value;

and if the knock evaluation value exceeds a set threshold range and is larger than the minimum boundary value in the set threshold range, increasing the ignition advance angle corresponding to the combustion chamber simulation model by a target angle value.

In still another possible implementation manner, the determining the knock evaluation value of the gas engine based on the pressure change curve of the test point includes:

performing Fourier transform on the pressure change curve of each test point aiming at each test point to obtain a converted knock trend curve, wherein the knock trend curve comprises knock values at different moments in the gas combustion simulation process;

and determining the maximum knock value in the knock trend curve as a knock evaluation value of the gas engine.

In yet another possible implementation manner, before the gas combustion simulation using the combustion chamber simulation model, the method further includes:

obtaining test result information of a single cylinder engine test corresponding to the gas engine;

calibrating modeling parameters for simulating gas combustion associated with a combustion chamber simulation model of the gas engine based on the test result information;

Performing natural gas combustion simulation of the combustion chamber simulation model based on the modeling parameters to obtain simulation result information;

if the deviation between the simulation result information and the test result information exceeds a set threshold value, adjusting modeling parameters associated with the combustion chamber simulation model, and returning to execute the operation of performing natural gas combustion simulation of the combustion chamber simulation model based on the modeling parameters;

if the deviation between the simulation result information and the test result information does not exceed a set threshold, determining the modeling parameter currently associated with the combustion chamber simulation model as the standard modeling parameter of the combustion chamber simulation model;

the gas combustion simulation by using the combustion chamber simulation model comprises the following steps:

and carrying out gas combustion simulation by using the combustion chamber simulation model based on the standard modeling parameters related to the combustion chamber simulation model.

In yet another aspect, the present application provides an apparatus for determining a design parameter of a piston, comprising:

the model building unit is used for building a combustion chamber simulation model of the gas engine based on the mechanical structure and initial design parameters of a piston of the gas engine, wherein the combustion chamber simulation model at least comprises a simulated piston model and a simulated spark plug model;

The simulation processing unit is used for carrying out gas combustion simulation by using the combustion chamber simulation model, and obtaining pressure values of each test point in the top of the piston model at different moments to obtain a pressure change curve of each test point;

a knock evaluation unit for determining a knock evaluation value of the gas engine based on a pressure change curve of the test point;

an advance angle adjustment unit configured to adjust, if there is a knock evaluation value exceeding a set threshold range, an advance angle of ignition corresponding to the combustion chamber simulation model, and based on the adjusted advance angle of ignition, return to executing the operation of performing gas combustion simulation using the combustion chamber simulation model;

an index obtaining unit, configured to obtain an average turbulence energy ratio in the combustion chamber simulation model in a gas combustion simulation process, an average gas flow velocity in the spark plug model setting range, and a change map of a target temperature isosurface in the combustion chamber simulation model if there is no knock evaluation value exceeding the setting threshold range, where the average turbulence energy ratio is a ratio of average turbulence energy on an intake side to average turbulence energy on an exhaust side of the combustion chamber simulation model, and the target temperature isosurface is a temperature isosurface with a target temperature value;

And the parameter determining unit is used for determining target design parameters of the piston in the gas engine based on the average turbulence energy ratio, the average gas flow speed and the change chart of the target temperature isosurface.

In one possible implementation manner, the parameter determining unit includes:

the index output unit is used for outputting a change chart of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface;

an adjustment value obtaining unit configured to, if a design parameter adjustment value of the piston input by a user is obtained, adjust a simulated piston model based on the design parameter adjustment value, and return to perform an operation of the simulation processing unit;

and the target parameter determining unit is used for taking the design parameter adopted by the last simulation of the piston model as the target design parameter of the piston in the gas engine if the simulation completion instruction input by the user is obtained.

According to the application, in the process of carrying out gas combustion simulation by using the combustion chamber simulation model of the gas engine, the pressure condition of each test point at the top of the piston model in the combustion chamber simulation model can be obtained, and the knocking of the cylinder of the gas engine is related to the pressure of the cylinder, so that the knocking condition of the gas engine can be determined by combining the pressure conditions of different test points at the top of the piston model, and the combustion chamber simulation model can be controlled to control the gas combustion simulation to a reasonable knocking level by reasonably adjusting the ignition advance angle corresponding to the combustion chamber simulation model, so that the combustion chamber simulation model can more truly simulate the gas combustion condition of the combustion chamber of the gas engine. On the basis, the gas combustion effect in the gas engine cylinder is considered to be related to turbulence energy distribution in the combustion chamber, gas flow speed near the spark plug and flame combustion distribution, so that the ratio of average turbulence energy of the air inlet side and the air outlet side in the combustion chamber simulation model in the gas combustion simulation process can be used as a judgment basis for evaluating the combustion condition in the combustion chamber of the gas engine, and a change chart of the equivalent surface of the target temperature and the average flow speed of the gas in the setting range of the spark plug model can be naturally used as a basis for evaluating whether the design parameters of the piston design are reasonable or not, and accordingly the design parameters suitable for the piston can be reasonably determined.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only embodiments of the present application, and other drawings may be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of a method for determining design parameters of a piston according to an embodiment of the present application;

FIG. 2 shows a schematic view of a body flow region and a squish flow region within a cylinder;

FIG. 3 shows a schematic cross-sectional view of a piston provided by an embodiment of the present application;

FIG. 4 shows a schematic cross-sectional view of a piston crown in an embodiment of the application;

FIG. 5 shows a schematic top view of a piston crown in an embodiment of the application;

FIG. 6 shows a schematic view of the centerline of a piston and the centerline and two boundaries of a combustion chamber pocket of the piston in accordance with an embodiment of the present application;

FIG. 7 shows an overall schematic of a cylinder head in an embodiment of the application;

FIG. 8 shows a schematic cross-sectional view of a cylinder head in accordance with an embodiment of the present application;

FIG. 9 illustrates a schematic flow diagram for calibrating a combustor simulation model in an embodiment of the application;

FIG. 10 illustrates design parameters associated with designing a piston in an embodiment of the present application;

fig. 11 is a schematic view showing a constitution of an apparatus for determining design parameters of a piston in the embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without any inventive effort, are intended to be within the scope of the application.

Referring to fig. 1, which is a schematic flow chart of a method for determining a design parameter of a piston according to an embodiment of the present application, the method of the present embodiment may include:

s101, constructing a combustion chamber simulation model of the gas engine based on the mechanical structure and initial design parameters of a piston of the gas engine.

Because the main purpose of the application is to reasonably determine the design parameters of the piston, the construction of the simulation model of the combustion chamber at least needs the mechanical structure and the initial design parameters of the piston, and correspondingly, the simulation model of the combustion chamber necessarily comprises the simulated piston model.

It will be appreciated that the cylinder of a gas engine may include components such as a cylinder head, a piston, and a spark plug, while the space for combustion gas formed by the piston crown, cylinder head wall, etc. is the combustion chamber. The combustion chamber simulation model is a simulation system model constructed for simulating combustion of the combustion chamber in the gas engine. Based on this, the combustion chamber simulation model may include a simulated cylinder head model, a spark plug model, and other related models in addition to the piston model, which will not be described in detail. The simulated piston model, cylinder cover model, spark plug model and the like and the combustion chamber enclosed by the models are taken as a combustion chamber simulation model as a whole.

Correspondingly, the construction of the simulation model of the combustion chamber also needs to refer to the mechanical structure and design parameters of a cylinder cover, a spark plug and the like. Of course, if the simulation structures of the cylinder head and the spark plug can also be constructed and configured in advance, the combustion chamber simulation model can be simulated only by inputting the mechanical structure and design parameters of the piston.

S102, performing gas combustion simulation by using a combustion chamber simulation model, and obtaining pressure values of all test points in the top of a piston of the piston model at different moments to obtain a pressure change curve of each test point.

The gas combustion simulation by using the combustion chamber simulation model is to simulate the combustion process of gas in the combustion chamber.

It will be appreciated that as the gas combustion simulation proceeds, the pressure at the piston top of the piston model in the combustion chamber simulation model also varies. In order to accurately obtain the pressure condition of the piston top, the application can set a plurality of test points on the piston top of the piston model in advance, and the plurality of test points can be uniformly distributed on the piston top plane of the piston model so as to more accurately reflect the pressure condition on the piston top plane.

And for each test point at the top of the piston model, generating a curve of the pressure change of the test point along with time based on the pressure values of the test point at different moments in the gas combustion simulation process, and obtaining a pressure change curve.

S103, determining a knock evaluation value of the gas engine based on the pressure change curve of the test point.

It will be appreciated that the piston crown of the piston is directed into the combustion chamber and that the pressure change at the piston crown test point may reflect the pressure in the combustion chamber. And the pressure conditions in the combustion chamber, i.e. in the cylinder, may reflect the knocking conditions of the gas engine. Based on this, the present application can determine the knock evaluation value for reflecting the knock condition of the gas engine in combination with the pressure change condition of the test point.

For example, in one possible implementation, for each test point, a fourier transform may be performed on the pressure change curve for that test point to obtain a transformed knock trend curve. The knock trend curve may represent knock values at different times during the gas combustion simulation. On the basis of this, the maximum knock value corresponding to the knock trend curve may be determined as the knock evaluation value of the gas engine.

S104, if the knock evaluation value exceeding the set threshold range exists, adjusting the ignition advance angle corresponding to the combustion chamber simulation model, and returning to execute the operation of the step S102 based on the adjusted ignition advance angle.

It will be appreciated that knock in a gas engine is too small and may be detrimental to gas combustion in the gas engine; however, if knocking in the gas engine is too large, the safety of the gas engine may be affected, and therefore, in order to secure both the gas combustion effect in the gas engine and the safety of the gas engine, it is necessary to control the knocking of the gas engine within a certain threshold range.

Accordingly, in the combustion simulation control, in order to be able to better reduce the combustion situation in the combustion chamber of the real gas engine, it is also necessary to ensure that knocking in the simulated combustion chamber simulation model is within a certain threshold range. Based on this, if it is determined that the knock evaluation value exceeds the set threshold range based on the pressure change curve of a certain test point, that is, only the knock evaluation value corresponding to one test point exceeds the set threshold range, it is necessary to control the ignition advance angle so as to control the knock within a reasonable range.

The set threshold range can be set according to actual needs. For example, the set threshold range is [ 0.145,0.155 ].

The ignition advance angle refers to an angle through which the crankshaft rotates from the ignition timing to the time when the piston reaches compression top dead center.

There are many possibilities for the specific implementation of adjusting the igniter advance angle in the combustion chamber simulation model in the present application.

In one possible implementation, if there is a knock evaluation value that exceeds a set threshold range and is smaller than a minimum boundary value in the set threshold range, increasing the ignition advance angle corresponding to the combustion chamber simulation model by a target angle value; if there is a knock evaluation value exceeding a set threshold range and being greater than a minimum boundary value in the set threshold range, increasing the ignition advance angle corresponding to the combustion chamber simulation model by a target angle value.

For example, taking the set threshold range [ 0.145,0.155 ], the minimum boundary value is 0.145.

The target angle value may be set as required, for example, the target angle value may be 0.5 degrees.

S105, if no knocking evaluation value exceeding the set threshold range exists, obtaining a change chart of an average turbulence energy ratio in a combustion chamber simulation model, an average gas flow speed in a spark plug model set range and a target temperature isosurface in the combustion chamber simulation model in the gas combustion simulation process.

The average turbulence energy ratio is the ratio of the average turbulence energy of the air inlet side to the average turbulence energy of the air outlet side of the combustion chamber simulation model. The air inlet side may be a spatial region in a first distance range near the air inlet end in the combustion chamber of the combustion chamber simulation model, the air outlet side is a spatial region in a second distance range near the air outlet end in the combustion chamber of the combustion chamber simulation model, and the first distance range and the second distance range may be set as required.

For example, the combustion chamber in the simulation model of the combustion chamber is divided into two partial space regions by the plane where the center line of the piston model is located, one partial space region of the two partial space regions is close to the air inlet end, the other partial space region is close to the air outlet end, then the space region close to the air inlet end can be determined to be the air inlet side, and the space region close to the air outlet end is determined to be the air outlet side, so that the average turbulence energy of each of the air inlet side and the air outlet side in the gas simulation combustion process is calculated through simulation software, and the average turbulence energy of each of the air inlet side and the air outlet side is obtained.

The setting range of the spark plug model may be set as desired, and may be, for example, within a space range of 0.5 mm in the vicinity of the spark plug model. Similarly, the average gas flow rate in the set range of the spark plug model can be obtained by collecting the gas flow rate in the set range of the spark plug model during the gas combustion simulation and calculating the average value, and the specific process is not limited.

The target temperature isosurface is a temperature isosurface with the temperature in the combustion chamber of the combustion chamber simulation model as a target temperature value. The target temperature isosurface in the combustion chamber can reflect the propagation condition of the flame surface in the combustion chamber, such as whether the flame surface is uniform, whether pits exist or the propagation speed is slower, and the like. The target temperature value can be set according to the needs, for example, in order to accurately reflect the propagation condition of the flame surface in the combustion chamber, a temperature equivalent surface with the target temperature value of 1500-1800K can be generally selected.

S106, determining target design parameters of the piston in the gas engine based on the average turbulence energy ratio, the average gas flow speed and the change chart of the target temperature isosurface.

For example, the change graph of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface is used as an evaluation index for determining the design parameters of the piston in the gas engine, so that the evaluation indexes are output to provide basis for determining the target design parameters of the piston.

In one possible implementation, a map of changes in average turbulence energy values, average gas flow rates, and target temperature isosurfaces may be output for viewing by a user. On this basis, if the design parameter adjustment value of the piston input by the user is obtained, the simulated piston model is adjusted based on the design parameter adjustment value, and the operation of step S102 is performed back. And if the simulation completion instruction input by the user is obtained, taking the design parameter adopted by the last simulation of the piston model as the target design parameter of the piston in the gas engine.

The target design parameters are a set of target design parameters, which may include design parameters of different indexes in the piston, such as a set of design parameters may include depth values of combustion chamber pits in the piston, radii of the combustion chamber pits, and the like.

It will be appreciated that in practical applications, based on the average turbulence energy ratio, the average flow velocity of the gas, and the change map of the target temperature isosurface, the user may provide one or more design parameter adjustment schemes each time, where each design parameter adjustment scheme includes at least one index design parameter adjustment value in the piston, so that for each design parameter adjustment scheme, it is necessary to return to step S102 again, and there may be multiple sets of target design parameters that eventually meet the combustion requirement, and thus, the final determination may be at least one set of target setting parameters.

Furthermore, after the application obtains at least one set of target setting parameters of the piston, the application can also produce a test piece of the single-cylinder gas engine aiming at each set of target setting parameters, and perform a single-cylinder engine test based on the test piece so as to select a set of target design parameters corresponding to the condition of the best gas combustion effect, and the specific process is not limited.

It will be appreciated that the simulation model and simulation process may be implemented using any general purpose simulation software in the present application, and this is not a limitation. For example, the application can realize the construction of the simulation model of the combustion chamber, the gas combustion simulation and the calculation and the acquisition of related parameters by means of fluid dynamics (Computational Fluid Dynamics, CFD) simulation.

According to the application, in the process of carrying out gas combustion simulation by using the combustion chamber simulation model of the gas engine, the pressure condition of each test point at the top of the piston model in the combustion chamber simulation model can be obtained, and the knocking of the cylinder of the gas engine is related to the pressure of the cylinder, so that the knocking condition of the gas engine can be determined by combining the pressure conditions of different test points at the top of the piston model, and the combustion chamber simulation model can be controlled to control the gas combustion simulation to a reasonable knocking level by reasonably adjusting the ignition advance angle corresponding to the combustion chamber simulation model, so that the combustion chamber simulation model can more truly simulate the gas combustion condition of the combustion chamber of the gas engine. On the basis, the gas combustion effect in the gas engine cylinder is considered to be related to turbulence energy distribution in the combustion chamber, gas flow speed near the spark plug and flame combustion distribution, so that the ratio of average turbulence energy of the air inlet side and the air outlet side in the combustion chamber simulation model in the gas combustion simulation process can be used as a judgment basis for evaluating other combustion conditions in the combustion chamber of the gas engine, and a change chart of the equivalent surface of the target temperature and the average flow speed of gas in the setting range of the spark plug model can be naturally used as a basis for evaluating whether design parameters of the piston design are reasonable or not, and accordingly, the proper design parameters of the piston can be reasonably determined.

It will be appreciated that the solution of the application can be applied to pistons of any mechanical structure in current gas engines, without limitation.

Considering that combustion chambers in many gas engines are developed aiming at vortex air intake forms, large extrusion flows are mainly adopted to improve the flow intensity in a cylinder, but the large-intensity extrusion flows are unfavorable to the organization of rolling flows in the cylinder, and the upward travel extrusion flows and the rolling flows are obvious in a flushing manner, as shown in fig. 2. The squeeze flow impingement affects the in-cylinder tumble flow tissue and creates a flow dead zone that impedes flame propagation. In addition, the extrusion flow affects the main flow, so that the main flow rolling flow strength is reduced, the axial deviation turbulence energy is reduced, the high turbulence energy area is far away from the spark plug, and finally, the flame propagation is slow, the oil consumption is poor, and the air flow dead zone is extremely easy to knock. Therefore, a practical and effective combustion chamber scheme is lacking at present, and the cylinder internal flow is organized by matching with a tumble air inlet mode, so that the air consumption is further reduced.

Based on the above, the application can improve the gas flow in the cylinder of the gas engine, reduce and improve the overall turbulence energy level and accelerate the gas combustion in the cylinder by adjusting the mechanical structures of the piston and the cylinder cover related to the combustion chamber.

In one possible implementation, the piston includes: the combustion chamber comprises a combustion chamber pit, a piston top surface surrounding the circumference of the combustion chamber pit and a transition inclined surface connecting the piston top surface and the piston side edge. Wherein the piston top surface is an annular plane and is higher than the piston side surface.

Wherein, the bottom center of the combustion chamber pit is provided with a bottom bulge part extending to the opening of the combustion chamber pit. That is, the bottom bulge portion extends from the bottom of the combustion chamber pit toward the opening of the combustion chamber pit to form a bulge.

The surface of the combustion chamber pit is a combination of a part of a spherical surface and the surface of the bottom bulge part, and the spherical surface part of the combustion chamber pit is in smooth transition connection with the surface of the bottom bulge part.

The description is made in connection with fig. 3 to 5:

fig. 3 is a cross-sectional view of the piston taken along the plane of the piston centerline, and fig. 4 is a top view of the piston crown. And figure 5 can be seen in a cross-sectional view of the piston crown portion shown in figure 4 along the plane of the piston centerline.

The X-X line indicated in FIG. 4 may be a line parallel to the centerline of the piston top surface. For example, the direction of the X-X line is parallel to the tumble direction in the combustion chamber, and the X-X line intersects the center line of the piston, and the schematic diagram of fig. 3 can be obtained by cross-sectioning the piston along the plane passing through the center line of the piston and in the direction of the X-X line.

Wherein the organized air swirling flow around the axis perpendicular to the cylinder axis formed during the intake of the gas engine is called tumble flow. And the flow direction of the tumble flow is the tumble flow direction.

As seen in fig. 3, the piston includes a combustion chamber pocket 301, a piston top surface 302, and a transition chamfer 303.

As can be seen in connection with fig. 3, 4 and 5, the piston combustion chamber pocket 301 is located at the top of the piston, while fig. 4 shows that the piston top surface 302 is an annular flat surface surrounding the axial direction of the combustion chamber pocket 301.

As can be seen in connection with fig. 3, the piston top surface 302 is higher than the piston side edges 304 and the piston top surface is connected to the piston side edges by transition slopes 303, whereas it can also be seen from fig. 3 and 4 that the transition slopes 303 gradually slope downwards in a radial direction along the centre to the outer edge of the combustion chamber pocket.

As is evident from a combination of fig. 3, the piston of the present application is no longer in the form of a flat top, the piston top surface portion protruding into the combustion chamber due to the presence of the transition bevel, such that the piston has a convex top surface. The transition inclined plane at the top of the piston can influence the actual extrusion flow of the combustion chamber, and the influence of edge change extrusion flow on the central large-scale tumble is changed, so that the flame diffusion condition in the cylinder is changed.

Specifically, the extrusion flow size of the combustion chamber and the influence degree of extrusion flow on the central large-scale tumble flow can be controlled by reasonably designing the included angle between the transition inclined plane of the horizontal plane and the width of the transition inclined plane, so that the flame diffusion condition in the cylinder is changed.

In the application, the bottom center of the combustion chamber pit is provided with the bottom bulge part extending from the bottom of the combustion chamber pit to the opening direction of the combustion chamber pit, and the bulge of the bottom bulge part can change the center of large-scale flow in the cylinder, thereby achieving the purposes of improving turbulent energy distribution and improving flame propagation speed.

As shown in fig. 3-5, the bottom intermediate region of the combustion chamber pocket has a bottom raised portion 305.

As can be seen in fig. 4, the surface of the combustion chamber pocket 301 of the piston comprises a portion of a spherically curved surface and a surface of the bottom raised portion 305, and the spherically curved surface is smoothly connected to the bottom raised portion of the combustion chamber pocket bottom.

In the present application, the bottom convex portion is a curved surface protruding toward the opening direction of the combustion chamber pit. In one alternative, the surface of the bottom raised portion is a portion of an ellipsoidal curved surface or a portion of a spherical curved surface that projects toward the opening of the combustion chamber pocket. When the surface of the bottom convex portion is also a part of the spherically curved surface, the surface other than the bottom convex portion in the combustion chamber may be referred to as a part of the first spherically-shaped surface, and the spherically-curved surface corresponding to the bottom convex portion may be referred to as a second spherically-shaped surface for convenience of distinction.

As is apparent from a combination of fig. 3 and 5, the intersection line of the combustion chamber pit and the plane passing through the center line of the piston is a pit-shaped line, and the pit-shaped line includes three sections of smooth curves sequentially connected in a smooth transition manner, wherein the three sections of smooth curves are sequentially the first intersection line of the first spherical surface of the combustion chamber pit and the plane passing through the center line of the piston, the intersection line of the elliptical spherical surface curved surface corresponding to the convex part at the bottom, or the second spherical surface curved with the plane passing through the center line of the piston, and the second intersection line of the first spherical surface and the plane passing through the center line of the piston.

It will be appreciated that the spherical surface of the combustion chamber pit outside the convex portion of the bottom has a corresponding spherical radius, and that the space size of the combustion chamber pit may be different, which may also have an effect on the flow of gas and the turbulence energy distribution in the combustion chamber.

Further, in order to be able to more effectively change the centre of large-scale flow in a gas engine cylinder, in the present application the centre line of the combustion chamber pit of the piston is not coincident with the piston centre line of the piston, i.e. there is a deviation of the centre line of the combustion chamber pit from the piston centre line.

As shown in fig. 6, there is a distance between the piston centerline 61 and the centerline 62 of the combustion chamber pocket that does not coincide. Vertical lines 63 in fig. 6 represent the boundaries of the combustion chamber pockets.

On the basis of the above, the indexes of pit depth of the combustion chamber pit, maximum protrusion height of the protrusion part, deviation of the center line of the combustion chamber pit from the center line of the piston, inclination angle of the transition inclined plane, width and the like can influence the tumble or squeeze flow in the air inlet process of the combustion chamber, so that the design parameters of the design piston in the application can comprise parameter values for setting the indexes.

In the present application, the cylinder head with which the piston is associated may also be modified. In particular, the head top surface of the head may no longer be planar, but instead protrude outwardly in a direction extending from the combustion chamber to the outside of the combustion chamber, such that the head top surface is inclined upwardly relative to the horizontal plane.

As described with reference to fig. 7 and 8, fig. 7 is a schematic view of the overall structure of the cylinder head, and fig. 8 is a sectional view of the cylinder head obtained by dividing the cylinder head of fig. 7 by a vertical plane passing through the line X-X in fig. 7.

The X-X line and the direction thereof in FIG. 7 are the same as the previous meaning and are not described herein, and the Y-Y line is perpendicular to the X-X line and passes through the center of the cylinder head.

As can be seen in connection with fig. 7 and 8, the top surface of the cylinder head is inclined upwards with respect to the horizontal plane (i.e. in the direction away from the combustion chamber), the top surface of the cylinder head is inclined upwards with respect to the horizontal plane by an angle θ3 as in fig. 8, and the valve in the cylinder head is inclined upwards with respect to the horizontal plane by an angle θ5 as in fig. 8, the maximum vertical distance of the center of the cylinder head from the horizontal plane being l6. The minimum distance l7 from the edge of the top surface of the cylinder cover to the valve boundary.

The inclined angle of the top surface of the cylinder cover relative to the horizontal surface can influence the extrusion flow angle, and after the inclined angle is increased, the angle between the extrusion flow surface and the lower bottom plane of the air valve is smaller, and the trend that the extrusion flow is smoothly separated from the wall surface for flow is smaller when the transition is smoother; and the larger the volume of the extrusion flow area, the lower the extrusion flow speed, and the smaller the influence on the main flow gas. In addition, since the rolling flow direction of the main body in the cylinder is X-X direction, the extrusion flow in Y-Y direction is perpendicular to the rolling flow direction, and the rolling flow extrusion and even the direction change can be caused, so that the extrusion flow is thoroughly canceled.

Based on the piston structure, the application can output the change graph of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface for a user to check, and further input the total parameter adjustment value according to the specific conditions of the several indexes.

For example, in one possible scenario, if the average turbulence energy ratio is not greater than the set ratio, the user entered design parameter adjustment values for the piston include: the adjustment value of the radius of the projection of the axis of the bottom bulge part in the combustion chamber pit on the horizontal plane and the adjustment value of the central line deviation of the combustion chamber pit, wherein the central line deviation is the deviation of the central line of the combustion chamber pit relative to the central line of the piston.

As shown in fig. 9, the projected radius maximum protrusion height of the axis of the bottom protrusion portion in the combustion chamber pit on the horizontal plane may be as shown in fig. 9 l 4.

The centerline offset of the combustion chamber pocket can be seen as l5 in fig. 9.

As can be seen from the foregoing description, the offset of the bottom raised portion of the combustion chamber pit and the centerline of the combustion chamber pit from the centerline of the piston can affect the large-scale flow center in the cylinder and change the turbulence energy distribution, so that the turbulence energy distribution can be improved and the flame propagation speed can be increased by adjusting the values of the two design parameters in the piston.

If the average flow velocity of the gas is not greater than the set velocity value, the design parameter adjustment values of the piston input by the user include: a depth adjustment value of the maximum depth of the combustion chamber pocket, and a radius adjustment value of a spherical radius corresponding to a spherical surface (a first spherical surface or a spherical surface other than the bottom convex portion) in the combustion chamber pocket.

The maximum depth of the combustion chamber pocket may be as shown by l2 in fig. 9. The distance of the outer edge of the combustion chamber pocket from the centerline of the combustion chamber pocket is shown as l3 in fig. 9.

It has been found that the depth of the combustion chamber pocket and the radius of the sphere corresponding to the spherical surface outside the raised bottom portion of the combustion chamber pocket can affect the tumble flow strength during the combustion chamber intake process, thereby changing the gas flow rate near the spark plug. Based on this, by adjusting these two parameters, the tumble flow strength can be enhanced, and the gas flow speed near the spark plug can be improved, thereby improving the misfire phenomenon.

If the change graph of the target temperature isosurface shows that the flame surface in the simulation model of the combustion chamber is not uniformly spread, the design parameter adjustment values of the piston input by a user comprise: the length adjustment value of the projection line of the intersection line of the transition inclined plane and the plane passing through the center line of the piston in the horizontal plane, and the angle adjustment value of the included angle between the intersection line of the transition inclined plane and the plane passing through the center line of the piston and the projection line.

Wherein the projection line of the intersection line of the transition slope and the plane passing through the center line of the piston on the horizontal plane is shown as l1 in fig. 9.

The angle between the intersection of the transition bevel and a plane passing through the piston centerline and the projection line is shown as θ1 in fig. 9.

It will be appreciated from the foregoing that the angle of inclination (i.e. the angle between the intersection of the transition bevel and the plane passing through the centre line of the piston and the projection line) and the length (which is related to the length of the projection line of the intersection of the transition bevel and the plane passing through the centre line of the piston in the horizontal plane) of the transition bevel can change the actual squish flow of the combustion chamber and the influence of squish flow on the central large-scale tumble flow. Based on the method, the actual extrusion flow size can be reasonably controlled by adjusting the two parameters, and the influence of the extrusion flow on the central large-scale tumble is changed, so that the flame diffusion condition in the cylinder is changed.

In an alternative implementation, the average turbulence energy ratio not greater than the set ratio may be: the average turbulence energy ratio is not more than 1.2;

the average flow rate of the gas not greater than a set rate value includes: the average flow velocity of the gas is not more than 20 m/s.

Of course, in practical application, other possibilities of setting the ratio and the set speed according to the actual needs are also possible, which is not limited by the present application.

It can be understood that in the application, in order to enable the combustion chamber simulation model to more accurately reflect the combustion effect of the combustion chamber in the gas engine in the real environment, after the combustion chamber simulation model is constructed, the calibration of modeling parameters of the combustion chamber simulation model is also required.

Referring to FIG. 10, which illustrates a schematic flow diagram of a simulation model of a combustion chamber in an embodiment of the application, the flow of the embodiment may include:

s1001, test result information of a single cylinder engine test corresponding to the gas engine is obtained.

The single-cylinder engine test of the gas engine is to construct a single-cylinder gas engine for testing. The structure of the piston and the cylinder cover in the single-cylinder engine constructed in the application can be referred to the previous description, and will not be repeated here.

In order to simplify the single cylinder test, the gas engine inner piston may not have an inner cooling gallery in the single cylinder test in this step.

The test result information can comprise parameters reflecting the combustion state of the gas in the single cylinder engine test process. For example, the test result information may include parameter values of parameters such as intake air pressure, intake air temperature, cylinder pressure, ignition advance angle, wall temperature, and the like.

S1002, calibrating modeling parameters for simulating gas combustion, which are associated with a combustion chamber simulation model of the gas engine, based on test result information.

Wherein the modeling parameters may be related parameters affecting other combustion simulations of the combustor simulation model. For example, the modeling parameters may include: the chemical reaction rate coefficient and other gas combustion related coefficients are not limited thereto.

S1003, performing natural gas combustion simulation of a combustion chamber simulation model based on the modeling parameters to obtain simulation result information.

The simulation result information may include parameter values such as intake pressure and intake temperature, cylinder pressure and wall temperature, etc. corresponding to the relevant parameters in the test result information, without limitation.

S1004, if the deviation between the simulation result information and the test result information exceeds the set threshold, adjusting the modeling parameters associated with the combustor simulation model, and returning to the operation of executing step S1003.

If the deviation between the values of a certain parameter item exceeds the threshold corresponding to the parameter item, the deviation between the simulation result information and the test result information is considered to exceed the set threshold.

If the simulation result information and the test result information show that the modeling parameters related to the simulation model of the combustion chamber are unreasonable, the combustion simulation process and the test have large difference, so that the modeling parameters need to be adjusted.

S1005, if the deviation between the simulation result information and the test result information does not exceed the set threshold, determining the modeling parameter currently associated with the combustion chamber simulation model as the standard modeling parameter of the combustion chamber simulation model.

It will be appreciated that after the standard modeling parameters associated with the combustor simulation model are obtained, the gas combustion simulation may be performed using the combustor simulation model based on the standard modeling parameters associated with the combustor simulation model. Accordingly, the gas combustion simulation mentioned in the previous embodiment can be regarded as a gas combustion simulation using the combustion chamber simulation model after calibration of the standard modeling parameters.

Referring to fig. 11, which is a schematic view of a composition structure of an apparatus for determining design parameters of a piston according to an embodiment of the present application, the apparatus of the present embodiment may include:

a model construction unit 1101, configured to construct a combustion chamber simulation model of the gas engine based on a mechanical structure and initial design parameters of a piston of the gas engine, where the combustion chamber simulation model includes at least a simulated piston model and a simulated spark plug model;

the simulation processing unit 1102 is configured to perform gas combustion simulation by using the combustion chamber simulation model, and obtain pressure values of each test point in the piston top of the piston model at different moments, so as to obtain a pressure change curve of each test point;

a knock evaluation unit 1103 for determining a knock evaluation value of the gas engine based on a pressure change curve of the test point;

An advance angle adjustment unit 1104 for adjusting an advance angle of ignition corresponding to the combustion chamber simulation model if there is a knock evaluation value exceeding a set threshold range, and returning to perform the operation of performing gas combustion simulation using the combustion chamber simulation model based on the adjusted advance angle of ignition;

an index obtaining unit 1105, configured to obtain, if there is no knock evaluation value exceeding a set threshold range, an average turbulence energy ratio in the combustion chamber simulation model in a gas combustion simulation process, an average gas flow speed in the spark plug model set range, and a change map of a target temperature isosurface in the combustion chamber simulation model, where the average turbulence energy ratio is a ratio of average turbulence energy on an intake side to average turbulence energy on an exhaust side of the combustion chamber simulation model, and the target temperature isosurface is a temperature isosurface with a temperature being a target temperature value;

a parameter determination unit 1106 is configured to determine a target design parameter of a piston in the gas engine based on the average turbulence ratio value, the average flow velocity of the gas, and a variation map of a target temperature isosurface.

In one possible implementation, the parameter determining unit includes:

The index output unit is used for outputting a change chart of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface;

an adjustment value obtaining unit configured to, if a design parameter adjustment value of the piston input by a user is obtained, adjust a simulated piston model based on the design parameter adjustment value, and return to performing an operation of a simulation processing unit;

and the target parameter determining unit is used for taking the design parameter adopted by the last simulation of the piston model as the target design parameter of the piston in the gas engine if the simulation completion instruction input by the user is obtained.

In yet another possible implementation, the apparatus further includes: further comprises:

the test result obtaining unit is used for obtaining test result information of a single cylinder engine test corresponding to the gas engine before the simulation processing unit utilizes the combustion chamber simulation model to simulate gas combustion;

the parameter calibration unit is used for calibrating modeling parameters which are associated with a combustion chamber simulation model of the gas engine and used for simulating gas combustion based on the test result information;

the modeling simulation unit is used for carrying out natural gas combustion simulation of the combustion chamber simulation model based on the modeling parameters to obtain simulation result information;

The simulation adjustment unit is used for adjusting modeling parameters related to the combustion chamber simulation model and returning to execute the operation of the modeling simulation unit if the deviation between the simulation result information and the test result information exceeds a set threshold value;

the parameter determining unit is used for determining the modeling parameter currently associated with the combustion chamber simulation model as the standard modeling parameter of the combustion chamber simulation model if the deviation between the simulation result information and the test result information does not exceed a set threshold value;

the simulation processing unit is specifically used for performing gas combustion simulation by using the combustion chamber simulation model based on standard modeling parameters associated with the combustion chamber simulation model when performing gas combustion simulation by using the combustion chamber simulation model.

It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other. Meanwhile, the features described in the embodiments in the present specification may be replaced with or combined with each other to enable those skilled in the art to make or use the present application. For the apparatus class embodiments, the description is relatively simple as it is substantially similar to the method embodiments, and reference is made to the description of the method embodiments for relevant points.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The foregoing is merely a preferred embodiment of the present application and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present application, which are intended to be comprehended within the scope of the present application.

Claims (10)

1. A method of determining a piston design parameter, comprising:

based on the mechanical structure and initial design parameters of a piston of the gas engine, constructing a combustion chamber simulation model of the gas engine, wherein the combustion chamber simulation model at least comprises a simulated piston model and a simulated spark plug model;

performing gas combustion simulation by using the combustion chamber simulation model, and obtaining pressure values of all test points in the top of a piston of the piston model at different moments to obtain a pressure change curve of each test point;

determining a knock evaluation value of the gas engine based on the pressure change curve of the test point;

if the knocking evaluation value exceeding the set threshold range exists, adjusting the ignition advance angle corresponding to the combustion chamber simulation model, and returning to execute the operation of performing gas combustion simulation by using the combustion chamber simulation model based on the adjusted ignition advance angle;

If the knocking evaluation value exceeding the set threshold value range does not exist, obtaining an average turbulence energy ratio in the combustion chamber simulation model in the gas combustion simulation process, an average gas flow speed in the spark plug model set range and a change chart of a target temperature equivalent surface in the combustion chamber simulation model, wherein the average turbulence energy ratio is a ratio of average turbulence energy of an air inlet side and average turbulence energy of an air outlet side of the combustion chamber simulation model, and the target temperature equivalent surface is a temperature equivalent surface with a temperature being a target temperature value;

and determining target design parameters of pistons in the gas engine based on the average turbulence energy ratio, the average gas flow speed and a change chart of target temperature isosurface.

2. The method of claim 1, wherein the determining the target design parameters for the piston in the gas engine based on the average turbulence ratio value, the average gas flow velocity, and the plot of change in target temperature isosurface comprises:

outputting a change chart of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface;

if the design parameter adjustment value of the piston input by the user is obtained, adjusting the simulated piston model based on the design parameter adjustment value, and returning to execute the operation of performing gas combustion simulation by using the combustion chamber simulation model;

And if the simulation completion instruction input by the user is obtained, taking the design parameter adopted by the last simulation of the piston model as the target design parameter of the piston in the gas engine.

3. The method of claim 2, wherein the piston comprises a combustion chamber pocket, a piston top surface surrounding a circumference of the combustion chamber pocket, and a transition slope connecting the piston top surface and the piston side, wherein the piston top surface is an annular planar surface and the piston top surface is higher than the piston side surface;

the bottom center of the combustion chamber pit is provided with a bottom bulge part extending towards the opening of the combustion chamber pit;

the surface of the combustion chamber pit is a combination of a part of a spherical surface and the surface of the bottom bulge part, and the spherical surface part in the combustion chamber pit is in smooth transition connection with the surface of the bottom bulge part.

4. The method of claim 3, wherein if the average turbulence energy ratio is not greater than a set ratio, the user entered design parameter adjustment value for the piston comprises: the method comprises the steps of adjusting a value corresponding to the radius of the projection of the axis of the bottom bulge part in the combustion chamber pit on a horizontal plane, and adjusting the central line offset of the combustion chamber pit, wherein the central line offset is the offset of the central line of the combustion chamber pit relative to the central line of the piston, and the central line of the combustion chamber pit is not overlapped with the central line of the piston;

If the average flow velocity of the gas is not greater than a set velocity value, the user-entered design parameter adjustment values for the piston include: a depth adjustment value of the maximum depth of the combustion chamber pit and a radius adjustment value of a spherical radius corresponding to the spherical surface in the combustion chamber pit;

if the change graph of the target temperature isosurface shows that flame surface propagation is uneven in a combustion chamber simulation model, the design parameter adjustment value of the piston input by the user comprises: the length adjustment value of the projection line of the intersection line of the transition inclined plane and the plane passing through the center line of the piston in the horizontal plane, and the angle adjustment value of the included angle between the intersection line of the transition inclined plane and the plane passing through the center line of the piston and the projection line.

5. The method of claim 4, wherein the average turbulence energy ratio is not greater than a set ratio, comprising: the average turbulence energy ratio is not greater than 1.2;

the average flow rate of the gas not greater than a set rate value includes: the average flow velocity of the gas is not more than 20 m/s.

6. The method according to claim 1, wherein adjusting the ignition advance angle corresponding to the combustion chamber simulation model if there is a knock evaluation value exceeding a set threshold range, comprises:

If the knock evaluation value exceeds a set threshold range and is smaller than the minimum boundary value in the set threshold range, increasing the ignition advance angle corresponding to the combustion chamber simulation model by a target angle value;

and if the knock evaluation value exceeds a set threshold range and is larger than the minimum boundary value in the set threshold range, increasing the ignition advance angle corresponding to the combustion chamber simulation model by a target angle value.

7. The method of claim 1, wherein the determining a knock evaluation value of the gas engine based on the pressure change curve of the test point comprises:

performing Fourier transform on the pressure change curve of each test point aiming at each test point to obtain a converted knock trend curve, wherein the knock trend curve comprises knock values at different moments in the gas combustion simulation process;

and determining the maximum knock value in the knock trend curve as a knock evaluation value of the gas engine.

8. The method of claim 1, further comprising, prior to performing a gas combustion simulation using the combustion chamber simulation model:

obtaining test result information of a single cylinder engine test corresponding to the gas engine;

Calibrating modeling parameters for simulating gas combustion associated with a combustion chamber simulation model of the gas engine based on the test result information;

performing natural gas combustion simulation of the combustion chamber simulation model based on the modeling parameters to obtain simulation result information;

if the deviation between the simulation result information and the test result information exceeds a set threshold value, adjusting modeling parameters associated with the combustion chamber simulation model, and returning to execute the operation of performing natural gas combustion simulation of the combustion chamber simulation model based on the modeling parameters;

if the deviation between the simulation result information and the test result information does not exceed a set threshold, determining the modeling parameter currently associated with the combustion chamber simulation model as the standard modeling parameter of the combustion chamber simulation model;

the gas combustion simulation by using the combustion chamber simulation model comprises the following steps:

and carrying out gas combustion simulation by using the combustion chamber simulation model based on the standard modeling parameters related to the combustion chamber simulation model.

9. An apparatus for determining a piston design parameter, comprising:

the model building unit is used for building a combustion chamber simulation model of the gas engine based on the mechanical structure and initial design parameters of a piston of the gas engine, wherein the combustion chamber simulation model at least comprises a simulated piston model and a simulated spark plug model;

The simulation processing unit is used for carrying out gas combustion simulation by using the combustion chamber simulation model, and obtaining pressure values of each test point in the top of the piston model at different moments to obtain a pressure change curve of each test point;

a knock evaluation unit for determining a knock evaluation value of the gas engine based on a pressure change curve of the test point;

an advance angle adjustment unit configured to adjust, if there is a knock evaluation value exceeding a set threshold range, an advance angle of ignition corresponding to the combustion chamber simulation model, and based on the adjusted advance angle of ignition, return to executing the operation of performing gas combustion simulation using the combustion chamber simulation model;

an index obtaining unit, configured to obtain an average turbulence energy ratio in the combustion chamber simulation model in a gas combustion simulation process, an average gas flow velocity in the spark plug model setting range, and a change map of a target temperature isosurface in the combustion chamber simulation model if there is no knock evaluation value exceeding the setting threshold range, where the average turbulence energy ratio is a ratio of average turbulence energy on an intake side to average turbulence energy on an exhaust side of the combustion chamber simulation model, and the target temperature isosurface is a temperature isosurface with a target temperature value;

And the parameter determining unit is used for determining target design parameters of the piston in the gas engine based on the average turbulence energy ratio, the average gas flow speed and the change chart of the target temperature isosurface.

10. The apparatus according to claim 9, wherein the parameter determination unit includes:

the index output unit is used for outputting a change chart of the average turbulence energy ratio, the average gas flow speed and the target temperature isosurface;

an adjustment value obtaining unit configured to, if a design parameter adjustment value of the piston input by a user is obtained, adjust a simulated piston model based on the design parameter adjustment value, and return to perform an operation of the simulation processing unit;

and the target parameter determining unit is used for taking the design parameter adopted by the last simulation of the piston model as the target design parameter of the piston in the gas engine if the simulation completion instruction input by the user is obtained.