共查询到20条相似文献，搜索用时 15 毫秒
1.
This paper presents a KIVA-3 code based numerical model for three-dimensional transient intake flow in the intake port-valve-cylinder
system of internal combustion engine using body-fitted technique, which can be used in numerical study on internal combustion
engine with vertical and inclined valves, and has higher calculation precision. A numerical simulation (on the intake process
of a two-valve engine with a semi-sphere combustion chamber and a radial intake port) is provided for analysis of the velocity
field and pressure field of different plane at different crank angles. The results revealed the formation of the tumble motion,
the evolution of flow field parameters and the variation of tumble ratios as important information for the design of engine
intake system. 相似文献
2.
利用AMESim软件建立了春风152MI小型单缸内燃机模型,基于发动机原始数据对发动机模型参数进行了设置,并验证了模型的正确性;利用VVT凸轮移相原理改变模型中进气凸轮相位,研究其扭矩及功率的变化。结果表明：随转速的升高,进气迟闭角越大扭矩越大,功率也越大。 相似文献
3.
Bülent 《浙江大学学报(A卷英文版)》2010,11(2):106-114
In this study, an electro-mechanical valve （EMV） system for the intake valve ofa fottr stroke, single cylinder, overhead valve and spark ignition （SI） engine was designed and constructed. An engine with the EMV system and a standard engine were tested to observe the effects of the EMV on engine performance and emissions at different speeds under full load. The EMV engine showed improved engine power, engine torque and break specific fuel consumption （BSFC）. A 66% decrease in CO emissions was also obtained with the EMV system, but hydrocarbons （HC） and NOx emissions increased by 12% and 13% respectively. 相似文献
4.
This work investigates the effects of exhaust gas recirculation (EGR) and operation parameters including engine speed, equivalence ratio, coolant-out temperature, and intake charge temperature on the basic characteristics of a single-cylinder homogeneous charge compression ignition (HCCI) engine powered with reformulated iso-octane fuels. The running range of iso-octane HCCI engine can be expanded to lower temperature and more load by adding di-tertiary butyl peroxide (DTBP) in the fuel. The combustion timing advances with the increase of DTBP concentrations, coolant temperature and equivalence ratio. The effects of EGR on the combustion and emissions are remarkable when the EGR rate is higher than 25%, and the combustion phase is sharply postponed and the UHC and CO emissions deteriorate. The intake charge temperature has a moderate effect on combustion and emissions when it is lower than 35°C; but the combustion timing advances, the combustion duration shortens, and sometimes it leads to knock combustion when the intake charge temperature increases to above 35°C. 相似文献
5.
Virtual design and performance prediction of a silencing air cleaner used in an I.C. engine intake system 总被引：3，自引：0，他引：3
INTRODUCTION The primary function of an intake system is firstly to efficiently channel fresh air to the engine,and secondly to minimize intake noise emissions.There are a number of current approaches for devel-oping a more realistic method to improve intake sys-tem design.The objectives include more effective silencing performance to meet increasingly severe legislative targets for reduced noise on the one hand,with optimized engine performance and fuel economy accompanied by improvements… 相似文献
6.
The transverse injection flow field has an important impact on the flowpath design of scramjet engines. At present a combination of the transverse injection scheme and any other flame holder has been widely employed in hypersonic propulsion systems to promote the mixing process between the fuel and the supersonic freestream; combustion efficiency has been improved thereby, as well as engine thrust. Research on mixing techniques for the transverse injection flow field is summarized from four aspects, namely the jet-to-crossflow pressure ratio, the geometric configuration of the injection port, the number of injection ports, and the injection angle. In conclusion, urgent investigations of mixing techniques of the transverse injection flow field are pro- posed, especiaUy data mining in the quantitative analytical results for transverse injection flow field, based on results from multi-objective design optimization theory. 相似文献
7.
In this paper,a new pressure reducing valve(PRV) with an orifice plate is proposed.The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV.A numerical simulation method was used to investigate the PRV internal flow field and to analyze the throttling effects of the orifice plate and the transform of thermal parameters as outlet pressure,outlet temperature,velocity,and superheat.A structure improvement method for the valve body and orifice plate is put forward to reduce energy loss.The governing equations for internal flow numerical simulation are composed of the continuity,momentum,energy and k-ε transport equations,based on isotropic eddy viscosity theory.Different valve plug displacement models were built to describe the double throttling process.Our analysis shows that the steam pressure drops twice and the degree of superheat increases.There are also lots of eddies which clog the flow channel and disturb the steam flow in the valve cavity after the valve plug and the outlet cavity.After modifying the structure,the numerical results show a better performance of steam flow. 相似文献
8.
INTRODUCTION The use of dimethyl ether (DME) as an alterna-tive fuel appears to be a promising approach for si-multaneously minimizing NOx and soot emissionfrom conventional diesel engines. The lowself-ignition temperature of 508 K and the high oxy-gen content of 34.8 percent (mass fraction) are twomajor factors characterizing low soot and unburnedtotal hydrocarbon (THC) emissions. Since the firstintroduction of the concept by Sorenson and Mik-kelsen (19… 相似文献
9.
设计了一种应用于传统非可变配气正时的发动机进气系统的固定式单向阀.将该阀安装于发动机气缸体与化油器之间,在中低转速下可阻止已进入发动机气缸内的混合气发生倒流现象,从而能有效地降低传统发动机的燃油消耗率.介绍了单向阀簧片的3种运动形式和对应的影响因素,分析了簧片的设计要求,重点研究了簧片的运动规律,建立了所设计的单向阀簧片的运动微分方程式,并运用Matlab编程求解出簧片的理论固有频率,为单向阀的簧片的形状和限位板高度等的设计提供参考和依据. 相似文献
10.
The fuel dynamic transfer process, including fuel injection, fuel film deposition and evaporation in the intake port, was analyzed for spark ignition (SI) engines with port fuel injection (PFI). The influence of wall-wetting fuel film, especially its evaporation rate, upon the air-fuel ratio of in-cylinder mixtures was also discussed. According to the similarity principle, Fick??s law, the ideal gas equation and the Gilliland correlation, an evaporate prediction model of wall-wetting fuel film was set up and an evaporate prediction based dynamic fuel film compensator was designed. Through engine cold start tests, the wall-wetting temperature, which is the key input of the fuel film evaporate prediction model, was also modeled and predicted. Combined with the experimental data of the evaporation characteristics of ethanol-gasoline blends and engine calibration tests, all the parameters of the wall-wetting fuel film evaporate prediction model used in the fuel film compensator were identified. Square-wave disturbance tests of fuel injection showed that with the help of the fuel film compensator the response of the in-cylinder air-fuel ratio was significantly improved and the real air-fuel ratio always closely matched the expected ratio. The fuel film compensator was then integrated into the final air-fuel ratio controller, and the engine tests showed that the air-fuel ratio control error was less than 2% in steady-state conditions, and less than 4% in transient conditions. The fuel film compensator also showed good adaptability to different ethanol-gasoline blends. 相似文献
11.
The power of hydraulic piston engines is much affected by the on-off valves which control the fuel injection of the piston assembly. Therefore, the opening time of the seat valve used as the on-off valve is optimized by minimizing the axial flow forces on the spool. A damping sleeve with orifices is proposed to change the valve internal geometry. Experimental and numerical investigations of the flow forces acting on the spool with and without the proposed damping sleeve are carried out to identify the differences in the flow field and to minimize the forces’ effect. The simulated results fit the experimental results well. Both results show that the proposed damping sleeve affects the pressure distribution along the spool cone surface and the jet stream direction significantly. The effects of the orifice’s width, height, and relative sleeve installation positions on the flow field and cavitation are assessed using simulation methods. As a result of the flow field changing, the damping sleeve can reduce the flow forces significantly and even reverse the forces’ direction at the cost of a little flow loss. The opening time of the seat valve can be reduced by 31% to 0.67 ms by using the proposed damping sleeve. 相似文献
12.
A new method for the generation of orthogonal body-fitted grids is presented in this paper. The positions of boundary points
in the physical domain are adjusted to obtain orthogonal curvilinear grids without changing the value of ξ and η during the
numerical process. The densities of ξ and η are given in advance. Good results were achieved in the application of this method
on the cooling system of an internal combustion engine and a trail duct. 相似文献
13.
本文介绍了汽油机燃烧过程仿真模拟的类型,建立了汽油机燃烧的准维模型。编制了基于VisualBasic的数值模拟程序,并利用该程序计算了某汽油机的燃烧过程。 相似文献
14.
为优化内燃机构造与原理课程的课堂教学效果,结合教学实践经验,从教学内容和教学方法两个方面提出改革思路,改变传统的“教师讲,学生听”的填鸭式教学模式,从而充分调动学生学习的主动性和积极性,使学生在有限的时间内更好地掌握和理解内燃机的相关知识, 相似文献
15.
The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NO, , emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder. 相似文献
16.
The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NOx emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder. 相似文献
17.
Auto-ignition and heat release correlations for controlled auto-ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range.Furthermore,a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments.The heat release correlation was described in two parts,one is for the first slower heat release process at low temperature,and the other is for the second faster heat release process at high temperature.Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program.The results show that the predicted loads and ignition timings match closely with the measurements. 相似文献
18.
Jun-yi LIANG Jian-long ZHANG Xi ZHANG Shi-fei YUAN Cheng-liang YIN 《浙江大学学报(A卷英文版)》2013,14(8):535-553
To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultra- capacitors （UCs） could be a solution. The high power density feature of UCs can improve the performance of battery/UC hybrid energy storage systems （HESSs）. This paper presents a parallel hybrid electric vehicle （HEV） equipped with an internal combus- tion engine and an HESS. An advanced energy management strategy （EMS）, mainly based on fuzzy logic, is proposed to improve the fuel economy of the HEV and the endurance of the HESS. The EMS is capable of determining the ideal distribution of output power among the internal combustion engine, battery, and UC according to the propelling power or regenerative braking power of the vehicle. To validate the effectiveness of the EMS, numerical simulation and experimental validations are carried out. The results indicate that EMS can effectively control the power sources to work within their respective efficient areas. The battery load can be mitigated and prolonged battery life can be expected. The electrical energy consumption in the HESS is reduced by 3.91% compared with that in the battery only system. Fuel consumption of the HEV is reduced by 24.3% compared with that of the same class conventional vehicles under Economic Commission of Europe driving cycle. 相似文献
19.
Three-dimensional transient numerical simulation for gas exchange process in a four-stroke motorcycle engine 总被引：3，自引：0，他引：3
INTRODUCTION In-cylinder flow characteristics during fuel in-jection and subsequent interactions with fuel sprays and combustion are important effect on engine per-formance and exhaust emissions of an engine(Floch et al.,1998;Kim et al.,1999).Four key parameters control the flow field in an engine:the mean flow components,the stability of the mean flow,the tem-poral turbulence evolution during the intake and compression strokes,and the mean velocity near the spark gap at the time of ignit… 相似文献
20.
The flame structure of gasoline engine is complicated and has the characteristic of fractal geometry. A fractal combustion model was used to simulate the engine working cycle. Based on this model, the fractal dimension and laminar flame surface area of turbulent premixed flames were studied under different working conditions. The experimental system mainly includes an optical engine and a set of photography equipment used to shoot the images of turbulent flame of spark-ignition engine. The difference box-counting method was used to process 2D combustion images. In contrast to the experimental results, the computational results show that the fractal combustion model is an effective method of simulating the engine combustion process. The study provides a better understanding for flame structure and its propagation. 相似文献