CN115329508A - Method for optimizing passive prechamber of equivalence ratio engine - Google Patents
Method for optimizing passive prechamber of equivalence ratio engine Download PDFInfo
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Abstract
The embodiment of the application discloses a passive prechamber optimization method for an equivalence ratio engine, aiming at the influence degrees of different parameters on scavenging performance and heat release rate and the importance and correlation of the parameters, optimizing and sequencing the parameters to obtain the optimizing sequence of distribution diameter, helical angle, cone angle and aperture, optimizing by adopting the optimizing sequence and combining single parameter, and adopting the result of the last optimized parameter for the next parameter to be optimized, so that the relatively optimal solution applied to engineering design is obtained more easily, the simulation times are reduced, and the optimizing efficiency is improved.
Description
Technical Field
The application relates to the technical field of engines, in particular to a passive prechamber optimization method for an equivalence ratio engine.
Background
The combustion system comprises a precombustion chamber and a main combustion chamber, the combustion conditions of the precombustion chamber and the main combustion chamber are complex, and the CFD method is usually adopted to optimize the parameters of the precombustion chamber. Because the parameters of the precombustion chamber are numerous, if the optimal parameter combination is found by adopting a parameter combination method, a large amount of calculation is needed, so that the optimization of the precombustion chamber is long in time consumption and low in efficiency.
Disclosure of Invention
The application provides a passive prechamber optimization method for an equivalence ratio engine, so that the optimization time of the prechamber is shortened, and the optimization efficiency is improved.
In order to achieve the above object, the present application provides a method for optimizing a passive prechamber of an equivalence ratio engine, comprising:
s110, defining the ratio of the volume of a precombustion chamber to the compression volume of a cylinder, and the ratio of the total area of jet holes of the precombustion chamber to the volume of the precombustion chamber;
s120, simulating the pre-combustion chamber adopting the preset distribution diameter, the preset helical angle, the preset cone angle and the preset aperture, and determining a first optimization direction of the distribution diameter according to a simulation result;
s130, optimizing according to the first optimization direction to obtain a distribution diameter optimization result;
s140, simulating the prechamber adopting the distribution diameter optimization result, the preset helical angle, the preset taper angle and the preset aperture, and determining a second optimization direction of the helical angle according to the simulation result;
s150, optimizing according to the second optimization direction to obtain a spiral angle optimization result;
s160, simulating the pre-combustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the preset taper angle and the preset aperture, and determining a third optimization direction of the taper angle according to the simulation result;
s170, optimizing according to the third optimization direction to obtain a cone angle optimization result;
s180, simulating the precombustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the cone angle optimization result and a preset aperture, and determining a fourth optimization direction of the aperture according to the simulation result;
and S190, optimizing according to the fourth optimization direction to obtain an aperture optimization result.
Preferably, in the above method for optimizing the passive prechamber of the equivalence ratio engine, the optimizing in S130 specifically includes the steps of:
s131, selecting an optimized distribution diameter according to the first optimized direction;
s132, simulating a pre-combustion chamber adopting the optimized distribution diameter, the preset helical angle, the preset cone angle and the preset aperture;
s133, if the scavenging performance reflected by the simulation result meets the expectation, the optimization of the distribution diameter is finished, if the scavenging performance of the simulation result does not meet the expectation, a fifth optimization direction for optimizing the distribution diameter is obtained according to the simulation result, the optimized distribution diameter is selected according to the fifth optimization direction, and the process enters S132.
Preferably, in the above method for optimizing the passive prechamber of the equivalence ratio engine, the optimizing in S150 specifically includes:
s151, selecting an optimized spiral angle according to the second optimization direction;
s152, simulating a pre-combustion chamber adopting the distribution diameter optimization result, the optimized spiral angle, the preset taper angle and the preset aperture;
and S153, if the scavenging performance reflected by the simulation result meets the expectation, ending the optimization of the spiral angle, if the scavenging performance of the simulation result does not meet the expectation, obtaining a sixth optimization direction for optimizing the spiral angle according to the simulation result, selecting the optimized spiral angle according to the sixth optimization direction, and entering S152.
Preferably, in the above method for optimizing the passive prechamber of the equivalence ratio engine, the optimizing in S170 specifically includes:
s171, selecting an optimized cone angle according to a third optimization direction;
s172, simulating a pre-combustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the optimized cone angle and the preset aperture;
and S173, if the scavenging performance and the heat release rate reflected by the simulation result meet the expectation, ending the optimization of the cone angle, if the scavenging performance of the simulation result does not meet the expectation, obtaining a seventh optimization direction for optimizing the cone angle according to the simulation result, selecting the optimized cone angle according to the seventh optimization direction, and entering S172.
Preferably, in the above method for optimizing a passive prechamber of an equivalence ratio engine, the optimizing in S190 specifically includes:
s191, selecting an optimized aperture according to the fourth optimization direction;
s192, simulating a pre-combustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the cone angle optimization result and the optimized aperture;
and S193, if the scavenging performance and the heat release rate reflected by the simulation result meet the expectation, finishing the optimization of the aperture, if the scavenging performance of the simulation result does not meet the expectation, obtaining an eighth optimization direction of the optimized aperture according to the simulation result, selecting the optimized aperture according to the eighth optimization direction, and entering S192.
Preferably, in the above-mentioned equivalence ratio engine passive prechamber optimization method, the method further includes, after S190, S200, determining whether the scavenging performance and heat release rate of the prechamber using the distribution diameter optimization result, the helix angle optimization result, the cone angle optimization result, and the aperture optimization result satisfy expectations, and if so, ending the simulation, and if not, proceeding to step S110.
Preferably, in the above method for optimizing the passive prechamber of the equivalence ratio engine, in S120, the first optimization direction for determining the distribution diameter is specifically:
if the simulation result reflects that the intake air flow is too converged at the center of the precombustion chamber, the first optimization direction is to increase the distribution diameter;
if the simulation result reflects that the air inflow is too close to the wall surface, the first optimization direction is the reduced distribution diameter.
Preferably, in the above method for optimizing a passive prechamber of an equivalence ratio engine, in S140, the determining, according to the simulation result, the second optimization direction of the helix angle specifically includes:
if the simulation result reflects that the air inlet flow is tightly attached to the wall surface of the precombustion chamber, the second optimization direction is a reduced spiral angle;
the second optimized direction is to increase the helix angle if the simulation results reflect an intake air flow that converges at the center of the pre-chamber.
Preferably, in the above method for optimizing a passive prechamber of an equivalence ratio engine, in S160, the third optimization direction of the cone angle determined according to the simulation result is specifically:
if the simulation results reflect that the inlet flow cannot reach the vicinity of the electrode, the third optimization direction is to reduce the taper angle,
simulating the precombustion chamber adopting the reduced taper angle, and if the distribution range of the jet flow in the main combustion chamber is lower than the expected distribution range, adjusting the taper angle back;
if the simulation results reflect that the inlet flow can reach the vicinity of the electrodes, but the distribution range of the jet flow in the primary combustion chamber is lower than expected, a third optimization direction is to increase the cone angle,
and (4) simulating the precombustion chamber with the increased taper angle, and if the simulation result shows that the intake air flow cannot reach the vicinity of the electrode, adjusting the taper angle back.
Preferably, in the above method for optimizing a passive prechamber of an equivalence ratio engine, in S180, the fourth optimization direction of the aperture determined according to the simulation result is specifically:
if the simulation results reflect that the amount of residual exhaust gas near the electrode is less than the first expected amount and the penetration distance is lower than the expected value, the fourth optimization direction is to reduce the aperture,
simulating the precombustion chamber with the reduced aperture, and if the penetration distance is lower than an expected value, adjusting back the aperture;
if the simulation results reflect that the residual exhaust gas near the electrode is more than the second expected amount and the penetration distance is lower than the expected value, the fourth optimization direction is to increase the aperture,
the prechamber with increased aperture is simulated and, if the penetration is below the expected value, the aperture is adjusted back,
wherein the second predetermined amount is greater than the first predetermined amount.
Preferably, in the above method of passive prechamber optimization of an equivalence ratio engine, the ratio of the prechamber volume to the cylinder compression volume is 0.2-1.0%.
Preferably, in the above method for optimizing the passive prechamber of the equivalence ratio engine, the ratio of the total area of the orifices of the prechamber to the volume of the prechamber is 0.003-0.006mm-1.
The method for optimizing the passive prechamber of the equivalence ratio engine provided by the embodiment of the application is used for sequencing optimization sequences of parameters according to the influence degrees of different parameters on scavenging performance and heat release rate and the importance and correlation of the parameters to obtain the optimization sequences of distribution diameter, helical angle, cone angle and aperture.
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In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is obvious that the drawings in the following description are only examples or embodiments of the application, and that for a person skilled in the art, without inventive effort, further drawings can be derived from the presented drawings, and the application can also be applied to other similar scenarios from the presented drawings. Unless otherwise apparent from the context, or otherwise indicated, like reference numbers in the figures refer to the same structure or operation.
FIG. 1 is a schematic diagram of an equivalence ratio engine passive prechamber optimization method of the present application.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant application and are not limiting of the application. The described embodiments are only some embodiments of the present application and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.
It should be noted that, for the convenience of description, only the portions related to the related applications are shown in the drawings. The embodiments and features of the embodiments in the present application may be combined with each other without conflict.
It should be understood that "system", "apparatus", "unit" and/or "module" as used in this application is a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, other words may be substituted by other expressions if they accomplish the same purpose.
As used in this application and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" are intended to cover only the explicitly identified steps or elements as not constituting an exclusive list and that the method or apparatus may comprise further steps or elements. An element defined by the phrase "comprising a component of ' 8230 ' \8230; ' does not exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.
Wherein in the description of the embodiments of the present application, "/" indicates an inclusive meaning, for example, a/B may indicate a or B; "and/or" herein is merely an association describing an associated object, and means that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality" means two or more than two.
In the following, the terms "first", "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
Flow charts are used herein to illustrate operations performed by systems according to embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in the exact order in which they are performed. Rather, the various steps may be processed in reverse order or simultaneously. Meanwhile, other operations may be added to the processes, or a certain step or several steps of operations may be removed from the processes.
Please refer to fig. 1.
The flow and combustion conditions of gas in the precombustion chamber are complex, the parameters of the precombustion chamber are optimized by adopting a CFD (computational fluid dynamics) method, but the evaluation indexes are not uniform, the evaluation standards are not uniform, the parameters of the precombustion chamber are numerous, the influence degrees of the parameters on the scavenging performance and the heat release rate are different, certain correlation exists among the parameters, and if an optimal solution is found by adopting a parameter combination method, the possibility of missing the optimal solution exists, and a large amount of calculation needs to be carried out.
Some embodiments of the present application disclose a method of passive prechamber optimization for an equivalence ratio engine, comprising:
s110, defining the ratio of the volume of the precombustion chamber to the compression volume of the cylinder, and the ratio of the total area of jet holes of the precombustion chamber to the volume of the precombustion chamber;
s120, simulating the pre-combustion chamber adopting a preset distribution diameter, a preset spiral angle, a preset cone angle and a preset aperture, and determining a first optimization direction of the distribution diameter according to a simulation result;
s130, optimizing according to the first optimization direction to obtain a distribution diameter optimization result;
s140, simulating the prechamber adopting the distribution diameter optimization result, the preset spiral angle, the preset taper angle and the preset aperture, and determining a second optimization direction of the spiral angle according to the simulation result;
s150, optimizing according to the second optimization direction to obtain a spiral angle optimization result;
s160, simulating the precombustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the preset taper angle and the preset aperture, and determining a third optimization direction of the taper angle according to the simulation result;
s170, optimizing according to the third optimization direction to obtain a cone angle optimization result;
s180, simulating the precombustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the cone angle optimization result and the preset aperture, and determining a fourth optimization direction of the aperture according to the simulation result;
and S190, optimizing according to the fourth optimization direction to obtain an aperture optimization result.
S110, preliminarily determining the volume relation between the precombustion chamber and the cylinder according to the ratio of the volume of the precombustion chamber to the compression volume of the cylinder, and preliminarily determining the flame energy feeding capacity of the precombustion chamber to the main combustion chamber according to the ratio of the total area of jet holes of the precombustion chamber to the volume of the precombustion chamber; the method for optimizing the passive prechamber simulation of the equivalence ratio engine is to further optimize the prechamber on the basis of the defined parameters.
S120, simulating the pre-combustion chamber adopting the preset distribution diameter, the preset helical angle, the preset cone angle and the preset aperture, and determining the optimization direction of the distribution diameter according to the simulation result. The simulation results include simulation maps of residual exhaust gas, turbulent kinetic energy, fuel distribution, and heat release rate.
And analyzing the reason of the simulation result according to the simulation result. The distribution diameter affects the distribution of the intake air flow into the prechamber interior, which in turn affects the intake air energy loss. The intake energy loss mainly affects the scavenging performance, i.e., the distribution diameter affects the scavenging performance. And analyzing to obtain a first optimized direction of the distribution diameter according to the intake energy loss. The first optimization direction is the selection direction of the distribution diameter value, namely, the distribution diameter larger than the preset distribution diameter is selected for optimization, or the distribution diameter smaller than the preset distribution diameter is selected for optimization.
The preset distribution diameter is determined by a worker according to experience or relevant literature.
S130, optimizing according to the first optimizing direction to obtain a distribution diameter optimizing result.
S140, simulating the prechamber adopting the distribution diameter optimization result, the preset spiral angle, the preset taper angle and the preset aperture, and determining a second optimization direction of the spiral angle according to the simulation result. The simulation results include simulation maps of residual exhaust gas, turbulent kinetic energy, fuel distribution, and heat release rate.
And analyzing the simulation result according to the simulation result to obtain the reason of the simulation result, wherein the spiral angle influences the convergence condition of the intake flow at the edge and the center of the precombustion chamber. If the intake air flow converges at the edge of the pre-combustion chamber, or the intake air flow converges at the center of the pre-combustion chamber, the spiral angle needs to be adjusted, and if the intake air flow is uniformly distributed at the edge and the center of the pre-combustion chamber, the spiral angle does not need to be adjusted. The second optimization direction is a selection direction of the spiral angle value, i.e. whether a spiral angle larger than a preset spiral angle is selected for optimization or a spiral angle smaller than the preset spiral angle is selected for optimization.
The preset helix angle is also determined by the practitioner based on experience or relevant literature.
S150, optimizing according to the second optimizing direction to obtain a spiral angle optimizing result.
S160, simulating the precombustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the preset taper angle and the preset aperture, and determining a third optimization direction of the taper angle according to the simulation result. The simulation results include simulation maps of residual exhaust gas, turbulent kinetic energy, fuel distribution, and heat release rate.
And analyzing the reason of the simulation result according to the simulation result. The cone angle affects the scavenging effect near the electrode, as well as the heat release rate of the prechamber and main combustion chamber. And analyzing to obtain a third optimization direction of the cone angle according to the scavenging effect and the heat release rate. The third optimization direction is the selection direction of the cone angle value, namely, the cone angle larger than the preset cone angle is selected for optimization, or the cone angle smaller than the preset cone angle is selected for optimization.
The preset taper angle is also determined by the worker based on experience or relevant literature.
And S170, optimizing according to the third optimization direction to obtain a cone angle optimization result.
S180, simulating the precombustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the cone angle optimization result and the preset aperture, and determining a fourth optimization direction of the aperture according to the simulation result. The simulation results include simulation maps of residual exhaust gas, turbulent kinetic energy, fuel distribution, and heat release rate.
And analyzing the reason of the simulation result according to the simulation result. The pore size mainly affects the purging effect and penetration distance of the exhaust gas near the electrode. And obtaining a fourth optimized direction of the aperture according to the residual exhaust gas near the electrode and the analysis of the heat release rate of the precombustion chamber and the main combustion chamber. The fourth optimization direction is the selection direction of the aperture value, namely, the aperture larger than the preset aperture is selected for optimization, or the aperture smaller than the preset aperture is selected for optimization.
The preset aperture is also determined by the worker based on experience or relevant literature.
S190, optimizing according to the fourth optimization direction to obtain an aperture optimization result
This application optimizes through four parameters to the distribution diameter, helix angle, cone angle and the aperture of precombustion chamber to the precombustion chamber that makes after the optimal design compromises scavenging performance and precombustion chamber and main combustion chamber's heat release rate.
The application discloses an equivalence ratio engine passive prechamber optimization method, which establishes a general principle, a general evaluation index and a general evaluation standard, wherein the general principle is to take the scavenging performance into consideration and match with a main combustion chamber, the general evaluation index comprises the scavenging performance (the scavenging performance comprises residual waste gas, turbulent kinetic energy and fuel distribution) and the heat release rate of the prechamber and the main combustion chamber, and the general evaluation standard comprises that the prechamber is thoroughly scavenged, the residual waste gas at an electrode is less, the fuel distribution is dense, the turbulent kinetic energy is high, the combustion speed of the prechamber is high, the pressure difference between the prechamber and the main combustion chamber is large, and the penetration distance is large.
Establishing evaluation criteria of each parameter: the distribution diameter aims at reducing the loss of intake energy; the helical angle takes the scavenging of the center and the edge of the precombustion chamber into consideration; the cone angle gives consideration to the scavenging performance and the matching of the precombustion chamber and the main combustion chamber; the aperture gives consideration to the scavenging performance and the penetration distance of the jet flow.
The method is based on the research on a passive precombustion chamber system and the analysis and summary of a large number of CFDs, and can realize good scavenging and rapid combustion by guiding the optimization of the spray holes of the passive precombustion chamber according to the optimization method.
In the scheme, the parameters are optimized and sequenced according to the influence degree of different parameters (the parameters refer to distribution diameter, helical angle, cone angle and aperture) on scavenging performance and heat release rate and the importance and relevance of the parameters. Taking the distribution diameter as an example, the distribution diameter has a large influence on the scavenging performance, but has small correlation with other parameters, and the distribution diameter is optimized first and then is subsequently calculated by adopting a distribution diameter optimization result, so that the workload caused by combination of the parameters is reduced.
The method for optimizing the passive prechamber of the equivalence ratio engine is characterized in that optimization is carried out according to the sequence of the distribution diameter, the helical angle, the cone angle and the aperture, single-parameter optimization is adopted, the next parameter to be optimized adopts the result of the last optimized parameter, and compared with multi-parameter optimization, the method is easier to obtain a relatively optimal solution applied to engineering design, reduces simulation times and improves optimization efficiency.
The distribution diameter is the diameter of the circle formed at the intersection of the spray holes distributed in the circumferential direction and the inner wall of the precombustion chamber, and influences the distribution of the intake air flow entering from the spray holes, so that the intake air energy loss is influenced. The intake energy loss is the kinetic energy of the gas, and the energy given to the gas for the piston to push is given to the gas. And obtaining a first optimization direction of the distribution diameter according to the intake energy loss reflected by the simulation result. The two reasons for the intake energy loss are that the first is that the intake flow is too converged at the center of the pre-combustion chamber and collides in the pre-combustion chamber to cause the intake energy loss, and the second is that the intake flow is too close to the wall surface and causes the intake energy loss due to the friction between the intake flow and the wall surface.
The spiral angle is an included angle between the axis of the jet hole and a connecting line of the center of the jet hole and the center of the precombustion chamber, the spiral angle enables the intake air flow to generate certain spiral when entering the precombustion chamber, and the central scavenging and the edge scavenging of the precombustion chamber need to be considered. When the spiral angle is too large, the air inflow is tightly attached to the wall surface, the central scavenging effect is poor, and when the spiral angle is too small, the air inflow is in the center of the precombustion chamber, and the edge scavenging effect is poor; the helix angle is moderate, and both precombustion chamber edge and central scavenging can be considered.
The cone angle is an included angle between an umbrella shape formed by the jet holes arranged along the circumferential direction of the precombustion chamber and the central line of the precombustion chamber, so that the air inlet flow has axial component velocity and circumferential component velocity along the precombustion chamber, the axial component velocity is the upward movement velocity of the air inlet flow, whether the air inlet flow can reach the vicinity of the electrode or not is determined, the cone angle simultaneously influences the distribution range of jet flows in the main combustion chamber, and the heat release rate of the precombustion chamber and the main combustion chamber is influenced. The cone angle is too large, the axial partial velocity is insufficient, the air inflow can not reach the vicinity of the electrode, the cone angle is too small, the distribution range of the jet flow in the main combustion chamber is small, the space of the main combustion chamber can not be effectively utilized, and the heat release rate is reduced.
The aperture influences the total area of the jet holes, the total area of the jet holes is the hole number aperture, the influence is exerted on the scavenging performance, and the penetrating distance of jet flow is considered. The aperture is too big, and the orifice total area is big, and scavenging effect is good, but the pressure differential between prechamber and the main combustion chamber is little, and the efflux penetration is apart from for a short time, and the heat release rate descends, and the aperture undersize jets total area for a short time, and scavenging effect is poor, can't establish the pressure differential between sufficient prechamber and the main combustion chamber equally, and the heat release rate descends.
In some embodiments of the present application, the optimizing in S130 specifically includes the steps of:
s131, selecting an optimized distribution diameter according to the first optimization direction;
s132, simulating the precombustion chamber with the optimized distribution diameter, the preset helical angle, the preset taper angle and the preset aperture;
s133, if the scavenging performance reflected by the simulation result meets the expectation, the optimization of the distribution diameter is finished, if the scavenging performance of the simulation result does not meet the expectation, a fifth optimization direction for optimizing the distribution diameter is obtained according to the simulation result, the optimized distribution diameter is selected according to the fifth optimization direction, and the step S132 is entered.
The first optimization direction is an overall optimization direction of the distribution diameter, the fifth optimization direction may be the same as the first optimization direction, or may be opposite to the first optimization direction, and is specifically determined according to a simulation result.
In some embodiments of the present application, the optimizing in S150 specifically includes:
s151, selecting an optimized spiral angle according to the second optimization direction;
s152, simulating the precombustion chamber adopting the distribution diameter optimization result, the optimized spiral angle, the preset taper angle and the preset aperture;
and S153, if the scavenging performance reflected by the simulation result meets the expectation, ending the optimization of the spiral angle, if the scavenging performance of the simulation result does not meet the expectation, obtaining a sixth optimization direction for optimizing the spiral angle according to the simulation result, selecting the optimized spiral angle according to the sixth optimization direction, and entering S152.
The sixth optimization direction may be the same as the second optimization direction, or may be opposite to the second optimization direction, which is determined specifically according to the simulation result.
In some embodiments of the present application, the optimizing in S170 specifically includes:
s171, selecting an optimized cone angle according to a third optimization direction;
s172, simulating the precombustion chamber adopting a distribution diameter optimization result, a spiral angle optimization result, an optimized cone angle and a preset aperture;
and S173, if the scavenging performance and the heat release rate reflected by the simulation result meet the expectation, ending the optimization of the cone angle, if the scavenging performance of the simulation result does not meet the expectation, obtaining a seventh optimization direction for optimizing the cone angle according to the simulation result, selecting the optimized cone angle according to the seventh optimization direction, and entering S172.
The seventh optimization direction may be the same as the third optimization direction, or may be opposite to the third optimization direction, and is determined according to the simulation result.
In some embodiments of the present application, the optimizing in S190 specifically includes:
s191, selecting an optimized aperture according to the fourth optimization direction;
s192, simulating the precombustion chamber adopting a distribution diameter optimization result, a spiral angle optimization result, a cone angle optimization result and an optimized aperture;
and S193, if the scavenging performance and the heat release rate reflected by the simulation result meet the expectation, finishing the optimization of the aperture, if the scavenging performance of the simulation result does not meet the expectation, obtaining an eighth optimization direction of the optimized aperture according to the simulation result, selecting the optimized aperture according to the eighth optimization direction, and entering S192.
The eighth optimization direction may be the same as the fourth optimization direction, or may be opposite to the fourth optimization direction, and is determined according to the simulation result.
If the simulation result of the precombustion chamber adopting the distribution diameter optimization result, the helical angle optimization result, the cone angle optimization result and the aperture optimization result does not meet the requirement of scavenging performance and heat release rate, the method also comprises the step S200 of judging whether the scavenging performance and the heat release rate of the precombustion chamber adopting the distribution diameter optimization result, the helical angle optimization result, the cone angle optimization result and the aperture optimization result meet the expectation, if so, the simulation is finished, and if not, the method enters the step S110 and is optimized again to obtain the precombustion chamber of which the simulation result meets the expectation.
If the simulation result of the prechamber meets the requirements of scavenging performance and heat release rate, the process can also enter S110, try to increase the volume of the prechamber, optimize again and determine whether the volume of the prechamber has a further increased space.
And if the intake air energy loss reflected by the simulation result exceeds the expected intake air energy loss, judging the reason of the intake air energy loss. The reason for the energy loss of the intake air is two, one is that the scavenging air flow is too converged at the center of the precombustion chamber, the air in the precombustion chamber collides, and the other is that the scavenging air flow is too close to the wall surface, and the energy loss is increased by the friction between the scavenging air flow and the wall surface.
In S120, the first optimization direction for determining the distribution diameter is specifically:
if the simulation result reflects that the air inflow excessively converges at the center of the precombustion chamber, the air inflow converged at the center of the precombustion chamber collides with each other to cause air inflow energy loss, the distribution diameter needs to be increased, at the moment, the first optimization direction is the increased distribution diameter, if the simulation result reflects that the air inflow excessively closes to the wall surface, the air inflow and the wall surface rub to cause air inflow energy loss, the distribution diameter needs to be reduced, and at the moment, the first optimization direction is the reduced distribution diameter.
And if the simulation result reflects that the uniform scavenging airflow and turbulent kinetic energy distribution cannot be realized in the precombustion chamber, judging the reason causing the simulation result. The reason for the simulation result is that the scavenging air flow is tightly attached to the wall surface due to the overlarge spiral angle, or the scavenging air flow is converged at the center of the precombustion chamber due to the overlarge spiral angle.
In S140, the second optimization direction of the spiral angle determined according to the simulation result is specifically:
if the simulation result reflects that the intake air flow is tightly attached to the wall surface of the precombustion chamber, the second optimization direction is to reduce the helical angle,
if the simulation result reflects that the intake air flow is gathered at the center of the precombustion chamber, the second optimization direction is to increase the helical angle;
and if the simulation result reflects that the air inflow can take account of the center and the edge of the precombustion chamber and the scavenging effect is good, the operation goes to S150.
If the simulation result reflects that the air inflow can not reach the vicinity of the electrode, the cone angle is too large, the cone angle needs to be reduced, the axial speed of scavenging air flow needs to be increased, but the distribution of the jet flow in the main combustion chamber is narrowed after the cone angle is reduced, so that whether the heat release rate of the main combustion chamber meets the expectation needs to be further judged, and if the heat release rate of the main combustion chamber is deteriorated, the cone angle needs to be adjusted back; if the simulation result reflects that the scavenging air flow can reach the vicinity of the motor, but the ignition range of the main combustion chamber is narrow, the heat release rate is poor, which indicates that the taper angle is too small, the taper angle needs to be increased, the axial speed of the scavenging air flow is increased by the taper angle and is reduced, so that the scavenging air flow needs to be further judged to reach the vicinity of the electrode, and if the ascending distance of the scavenging air flow is reduced and the scavenging becomes worse, the taper angle needs to be adjusted back; if the spray hole taper angle can give consideration to both the scavenging performance and the heat release rate of the main combustion chamber, the optimization is finished, and the next step is carried out.
In S160, the third optimization direction of the cone angle determined according to the simulation result is specifically:
if the simulation results reflect that the inlet flow cannot reach the vicinity of the electrode, the third optimization direction is to reduce the taper angle, which is the overall adjustment trend of the taper angle,
simulating the precombustion chamber adopting the reduced taper angle, and if the distribution range of the jet flow in the main combustion chamber is lower than the expected distribution range, namely the heat release rate does not meet the expectation, adjusting back the taper angle;
if the simulation results reflect that the intake air flow can reach the vicinity of the electrode, but the distribution range of the jet flow in the main combustion chamber is lower than the expected range, namely the heat release rate does not meet the expectation, the third optimization direction is the increasing cone angle, the direction is the adjustment trend of the cone angle overall,
and simulating the prechamber with the increased taper angle, and if the scavenging ascending distance of the intake air flow is reduced and the scavenging effect at the electrode is deteriorated, adjusting back the taper angle.
If the simulation result reflects that the scavenging of the precombustion chamber is good, but the pressure difference between the precombustion chamber and the main combustion chamber is small, and the penetration distance of a jet flow is short, the pore diameter is overlarge, the pore diameter needs to be reduced to increase the pressure difference between the precombustion chamber and the main combustion chamber and the penetration distance of the jet flow, but the scavenging performance is deteriorated after the pore diameter is reduced, so that whether the penetration distance is reduced needs to be further judged, and if the penetration distance is reduced, the pore diameter needs to be adjusted back; if the simulation result reflects that the scavenging performance of the precombustion chamber is poor, so that the pressure difference between the precombustion chamber and the main combustion chamber is small, and the jet flow penetration distance is short, the aperture is small, the aperture needs to be increased to increase the amount of mixed gas entering the precombustion chamber from the main combustion chamber and improve the scavenging performance, but the throttling effect is weakened after the aperture is increased, whether the jet flow penetration distance is reduced needs to be further judged, and if the jet flow penetration distance is reduced, the aperture needs to be adjusted back; if the aperture can take the scavenging performance and the jet penetration distance into account, the optimization is finished.
In S180, determining the fourth optimization direction of the aperture according to the simulation result specifically includes:
if the simulation result reflects that the residual exhaust gas amount near the electrode is less than the first expected amount and the penetration distance is lower than the expected value, the fourth optimized direction is to reduce the aperture, which is the adjustment trend of the aperture as a whole,
simulating the precombustion chamber with the reduced aperture, and if the simulation result reflects that the penetration distance is reduced, adjusting back the aperture;
if the simulation results reflect that the residual exhaust gas near the electrode is more than the second expected amount and the penetration distance is lower than the expected value, the fourth optimization direction is to increase the aperture,
and (4) simulating the precombustion chamber with the increased aperture, and if the simulation result reflects that the penetration distance is reduced, adjusting back the aperture.
Wherein the second predetermined amount is greater than the first predetermined amount.
The ratio V0/Vc of the volume of the precombustion chamber to the compression volume of the cylinder is 0.2-1.0%, the initial value is 0.5% of the median, and the volume of the precombustion chamber is increased in the optimized direction; the ratio S0/V0 of the total area of the jet holes of the precombustion chamber to the volume of the precombustion chamber is 0.003-0.006mm < -1 >, and the initial value is 0.004mm < -1 >. The total area of the jet holes and the number of the holes are initially determined according to the initial values of V0/Vc and S0/V0.
The range of the spiral angle is 0-20 degrees, 0 degree corresponds to the radial hole, and the other spiral holes correspond to the spiral holes; the range of cone angles is defined by an initial value of 130 deg. with reference to the drop point of the jet in the main combustion chamber.
The foregoing description is only illustrative of the preferred embodiments of the present application and the principles of the technology employed and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. The scope of the application referred to in the present application is not limited to the specific combinations of the above-mentioned features, and it is intended to cover other embodiments in which the above-mentioned features or their equivalents are arbitrarily combined without departing from the spirit of the application. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Claims (12)
1. A method of passive prechamber optimization for an equivalence ratio engine, comprising:
s110, defining the ratio of the volume of a precombustion chamber to the compression volume of a cylinder, and the ratio of the total area of jet holes of the precombustion chamber to the volume of the precombustion chamber;
s120, simulating the pre-combustion chamber adopting a preset distribution diameter, a preset spiral angle, a preset cone angle and a preset aperture, and determining a first optimization direction of the distribution diameter according to a simulation result;
s130, optimizing according to the first optimization direction to obtain a distribution diameter optimization result;
s140, simulating the prechamber adopting the distribution diameter optimization result, the preset helical angle, the preset taper angle and the preset aperture, and determining a second optimization direction of the helical angle according to the simulation result;
s150, optimizing according to the second optimization direction to obtain a spiral angle optimization result;
s160, simulating the precombustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the preset taper angle and the preset aperture, and determining a third optimization direction of the taper angle according to the simulation result;
s170, optimizing according to the third optimization direction to obtain a cone angle optimization result;
s180, simulating the pre-combustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the cone angle optimization result and a preset aperture, and determining a fourth optimization direction of the aperture according to the simulation result;
and S190, optimizing according to the fourth optimization direction to obtain an aperture optimization result.
2. The equivalence ratio engine passive prechamber optimization method of claim 1, wherein the optimizing in S130 specifically comprises the steps of:
s131, selecting an optimized distribution diameter according to the first optimization direction;
s132, simulating a pre-combustion chamber adopting the optimized distribution diameter, the preset helical angle, the preset taper angle and the preset aperture;
and S133, if the scavenging performance reflected by the simulation result meets the expectation, finishing the optimization of the distribution diameter, if the scavenging performance of the simulation result does not meet the expectation, obtaining a fifth optimization direction for optimizing the distribution diameter according to the simulation result, selecting the optimized distribution diameter according to the fifth optimization direction, and entering S132.
3. The equivalence ratio engine passive prechamber optimization method of claim 1, wherein the optimizing in S150 specifically comprises:
s151, selecting an optimized spiral angle according to the second optimization direction;
s152, simulating a pre-combustion chamber adopting the distribution diameter optimization result, the optimized spiral angle, the preset taper angle and the preset aperture;
and S153, if the scavenging performance reflected by the simulation result meets the expectation, ending the optimization of the spiral angle, if the scavenging performance of the simulation result does not meet the expectation, obtaining a sixth optimization direction for optimizing the spiral angle according to the simulation result, selecting the optimized spiral angle according to the sixth optimization direction, and entering S152.
4. The equivalence ratio engine passive prechamber optimization method of claim 1, wherein the optimizing in S170 specifically comprises:
s171, selecting an optimized cone angle according to a third optimization direction;
s172, simulating a pre-combustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the optimized cone angle and the preset aperture;
and S173, if the scavenging performance and the heat release rate reflected by the simulation result meet the expectation, ending the optimization of the cone angle, if the scavenging performance of the simulation result does not meet the expectation, obtaining a seventh optimization direction for optimizing the cone angle according to the simulation result, selecting the optimized cone angle according to the seventh optimization direction, and entering S172.
5. The equivalence ratio engine passive prechamber optimization method of claim 1, wherein the optimizing in S190 specifically comprises:
s191, selecting an optimized aperture according to the fourth optimization direction;
s192, simulating a pre-combustion chamber adopting the distribution diameter optimization result, the spiral angle optimization result, the cone angle optimization result and the optimized aperture;
and S193, if the scavenging performance and the heat release rate reflected by the simulation result meet the expectation, finishing the optimization of the aperture, if the scavenging performance of the simulation result does not meet the expectation, obtaining an eighth optimization direction for optimizing the aperture according to the simulation result, selecting the optimized aperture according to the eighth optimization direction, and entering S192.
6. The equivalence ratio engine passive prechamber optimization method according to claim 1, further comprising, after S190, S200, judging whether the scavenging performance and heat release rate of the prechamber using the distribution diameter optimization result, the helix angle optimization result, the cone angle optimization result, and the aperture optimization result satisfy expectations, and if so, ending the simulation, and if not, proceeding to step S110.
7. The equivalence ratio engine passive prechamber optimization method according to claim 1, wherein in S120, the first optimization direction for determining the distribution diameter is specifically:
if the simulation result reflects that the intake air flow is too converged at the center of the precombustion chamber, the first optimization direction is to increase the distribution diameter;
and if the simulation result reflects that the inlet air flows too close to the wall surface, the first optimization direction is to reduce the distribution diameter.
8. The method for optimizing the equivalence ratio engine as claimed in claim 1, wherein in S140, the determining the second optimization direction of the helix angle according to the simulation result specifically comprises:
if the simulation result reflects that the air inlet flow is tightly attached to the wall surface of the precombustion chamber, the second optimization direction is a reduced spiral angle;
the second optimized direction is increasing the pitch angle if the simulation results reflect that the intake air flow is concentrated in the center of the prechamber.
9. The method for optimizing a passive prechamber for an equivalence ratio engine as claimed in claim 1, wherein in S160, the third optimization direction of the cone angle is determined from simulation results, specifically:
if the simulation results reflect that the inlet flow cannot reach the vicinity of the electrode, the third optimization direction is to reduce the taper angle,
simulating the precombustion chamber with the reduced taper angle, and if the distribution range of the jet flow in the main combustion chamber is lower than the expected distribution range, adjusting the taper angle back;
if the simulation results reflect that the inlet flow can reach the vicinity of the electrodes, but the distribution range of the jet flow in the primary combustion chamber is lower than the expected range, a third optimization direction is to increase the cone angle,
and (4) simulating the precombustion chamber with the increased taper angle, and if the simulation result shows that the intake air flow cannot reach the vicinity of the electrode, adjusting the taper angle back.
10. The equivalence ratio engine passive prechamber optimization method according to claim 1, wherein in S180, the fourth optimization direction for determining the aperture according to the simulation result is specifically:
if the simulation results reflect that the amount of residual exhaust gas near the electrode is less than the first expected amount and the penetration distance is lower than the expected value, the fourth optimized direction is to reduce the aperture,
simulating the precombustion chamber with the reduced aperture, and if the penetration distance is lower than an expected value, adjusting back the aperture;
if the simulation results reflect more residual exhaust gas near the electrode than the second expected amount and a penetration distance below the expected value, the fourth optimized direction is to increase the aperture,
the prechamber with increased aperture is simulated and, if the penetration is below the expected value, the aperture is adjusted back,
wherein the second predetermined amount is greater than the first predetermined amount.
11. The method of claim 1, wherein the ratio of prechamber volume to cylinder compression volume is 0.2-1.0%.
12. The method of claim 1, wherein the ratio of the total area of the orifices in the prechamber to the prechamber volume is 0.003-0.006mm "1.
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