Investigation of in-cylinder flow patterns in 4 valve S. I. Engine by using single-frame particle tracking velocimetry

The in-cylinder flow field of gasoline engine comprises unsteady compressible turbulent flows caused by the intake port, combustion chamber geometry. Thus, the quantitative analysis of the in-cylinder flow characteristics plays an important role in the improvement of engine performances and the reduction of exhaust emission. In order to obtain the quantitative analysis of the in-cylinder gas flows for a gasoline engine, the single-frame particle tracking velocimetry was developed, which is designed to measure 2-dimensional gas flow field. In this paper, influences of the swirl and tumble intensifying valves on the in-cylinder flow characteristics under the various intake flow conditions were investigated by using this PTV method. Based on the results of experiment, the generation process of swirl and tumble flow in a cylinder during intake stroke was clarified. Its effect on the tumble ratio at the end of compression stroke was also investigated.     

喷射装置导管对大缸径气体燃料发动机缸内混合效果的影响

在喷射装置出口加装导管,将燃气分别导向大缸径多点电喷气体燃料发动机的螺旋进气道和切向进气道,建立了联合喷射装置内部流动区域的发动机瞬态CFD计算模型,分析了导管位置对缸内掺混过程的影响。研究结果表明：对于该切向气道、螺旋气道的组合进气道,进气冲程在缸内靠近缸盖截面上产生了干涉涡流,对于螺旋气道喷射方案,燃气向气缸中心靠近,压缩末了时刻燃气集中在缸盖附近;而对于切向气道喷射方案,燃气冲向活塞顶,压缩末了时刻燃气集中在活塞顶附近。点火时刻的混合效果从优到劣依次为螺旋气道喷射方案、无导管喷射方案、切向气道喷射方案。     

基于FPGA的高压共轨柴油机快速判缸的研究

基于NI公司的软硬件平台，利用LabVIEW FPGA模块，对RIO设备进行配置，直接在硬件上开发了多传感器同步多速率信号采集模块及曲轴和凸轮轴脉冲周期测量模块；并根据凸轮轴信号片段特点，结合曲轴的缺齿信号，设计出一种可在任意相位下进行判缸的算法。验证表明，该任意相位下的判缸策略，提高了现有的判缸速度和精度，开发的功能模块运行可靠，移植性好。     

3102柴油机气缸盖设计

气缸盖是发动机中最复杂的部件之一。根据柴油机的性能指标选择了柴油机主要的性能参数,重点论述了3102柴油机气缸盖的设计依据与设计过程。同时,对气缸盖材料的选择、冷却水道的布置、进排气道布置以及缸盖螺栓的布置等问题也进行了讨论。     

A study on in-cylinder flow field of a 125cc motorcycle engine at low engine speeds

The in-cylinder flow characteristics of a four-stroke, four-valve, pent-roof small engine of motorcycle at engine speeds from 2000 rpm to 4000 rpm were studied using computational fluid dynamics (CFD). The aim of this study was to investigate the in-cylinder flow characteristics of small engines, including tumble, swirl, turbulent kinetic energy (TKE), angular momentum, in-cylinder air mass, turbulent velocity, turbulent length scale, and air flow pattern (in both intake and compression strokes) under motoring conditions. The engine geometry was created using SolidWorks, then was exported and analyzed using CONVERGE, a commercial CFD method. Grid independence analysis was carried out for this small engine and the turbulence model was observed using the renormalized group (RNG) k-ɛ model. The pressure boundary conditions were used to define the fluid pressure at the intake and exhaust of the port. The results showed that the increase in the engine speed caused the swirl flow in the small engine to be irregularly shaped. The swirl flow had a tendency to be stable and almost constant in the beginning of the compression stroke and increased at the end of compression stroke. However, the increase of in engine speed had no significant effect on the increase in tumble ratio, especially during the intake stroke. There was an increase in tumble ratio due to the increase in engine speed at the end of compression stroke, but only a marginal increase. The increase in engine speed had no significant effect on the increase in angular momentum, TKE, or turbulent velocity from the early intake stroke until the middle of the intake stroke. However, the angular momentum increased due to the increase in engine speed from the middle of the intake stroke to the end of compression stroke, and the angular momentum achieved the biggest increase when the engine speed rose from 3000 to 4000 rpm by 10 % at the end of the intake stroke. The increase in engine speed caused an increase of TKE and turbulent velocity from the middle of intake stroke until the end of compression stroke. Moreover, the biggest increase of TKE and turbulent velocity occurred when the engine speed rose from 3000 to 4000 rpm at the middle of intake stroke around 50 % and 25 %, respectively. Turbulent length scales appeared to be insensitive to increasing engine speed, especially in the intake stroke until 490 °CA. From that point, the value of the turbulent length scale increased as engine speed increased. The biggest increase in the turbulent length scales occurred when the intake valve was almost closed (around 20 %) and the engine speed was within two specific ranges (2000 to 3000 rpm and 3000 to 4000 rpm). Regarding the effect of engine speed, there were no significant effects upon the accumulated air mass in the small engine. The increase in engine speed caused an increase of turbulence in the combustion chamber during the late stages of the compression stroke. The increase in turbulence enhanced the mixing of air and fuel and made the mixture more homogeneous. Moreover, the increase in turbulence directly increased the flame propagation speed. Further research is recommended using a new design with several types of intake ports as well as combinations of different intake ports and some type of piston face, so that changes in air flow characteristics in small engines can be analyzed. Finally, this study is expected to help decrease the number of experiments necessary to obtain optimized systems in small engines.

     

直喷汽油机可变滚流进气系统实验研究

建立了可变滚流四气门直喷汽油机光学可视化气道实验台,利用粒子图像测速（PIV）系统对不同进气门开度、不同滚流调节阀工作状态下的缸内气流运动规律进行了实验测试研究。实验结果表明,缸内主要是绕气缸轴线垂直方向旋转的滚流运动;滚流阀开启时,缸内左右两侧分别形成逆时针和顺时针方向的两个大尺度滚流;滚流阀关闭时,进气门侧的气流减弱,排气门侧的流速明显增强,缸内出现了较强的单一顺时针方向滚流运动趋势;进气门开度较小时,改变滚流阀状态对缸内进气流动的影响很微弱。      

A study on the characteristics of in-cylinder intake flow in spark ignition engine using the PIV

In this study, to investigate m-cyhnder tumble or swirl intake flow of a gasoline engine, the flow characteristics were examined with opening control valve (OCV) and several swirl control valves (SCV) which intensify intake flow through steady flow experiment, and also turbulent characteristics of m-cyhnder flow field were investigated by 2-frame cross-correlation particle image velocimetry (PIV) method In the investigation of intake turbulent characteristics using PIV method, the different flow characteristics were showed according to OCV or SCV figures The OCV or SCV installed engine had higher vorticity and turbulent kinetic energy than a baseline engine, especially around the wall and lower part of the cylinder Above all, SCV B type was superior to the others About energy dissipation and reynolds shear stress distribution, a baseline engine had larger loss than OCV or SCV installed one because flow impinged on the cylinder wall It should be concluded, from what has been said above, as swirl component was added to existing tumble flow adequately, it was confirmed that turbulent intenstty was enlarged, flow energy was conserved effectively through the experiment In other words, there is a suggestion that flow characteristics as these affected to m-cyhnder combustion positively     

Introductory measurements of in-cylinder flow past intake valve ports with a film split-fiber probe

A new steady flow test bench test facility has been designed and fabricated for exploration of complex three-dimensional flowfields inside a cylinder of an internal combustion engine. An engine cylinder head of a currently produced car engine with four head valves is utilized as an inlet section of the newly built test bench test. No piston is located in the cylinder and the intake valves are not periodically operated. They remain open during the test periods. An extensive set of initial experimental data has been acquired for both open intake valves and for the location of the probes at two different axial stations in the engine cylinder. The experimental technique of thermo-anemometer split-fiber probes is employed in this research work, which is a novelty never applied before to this class of flows. The probe properties are explained in the paper with emphasis on the probe directional characteristics. The verification tests proved the operational readiness of the new test bench to acquire reliable experimental data at a range of flow conditions simulating real engine settings. The acquired data set base will be used for validations of improved CFD engine design codes. An analysis of the initial set of experimental data clearly indicates that two vortices, or more likely down-flowing spiral flow structures. are present side by side in the cylinder. Mutual interaction of these two flow structures and the ability to generate faithful numerical simulation of this flow pattern for additional planes of measurement and various valve openings will be reported separately.     

基于数值模拟优化分析的某型汽油机发动机燃烧系统正向开发

文中主要基于喷雾标定的结果进行发动机缸内燃烧系统的正向开发和优化.在喷雾试验数据的基础上建立了喷雾模型,并利用喷雾模型和发动机相关数据进行了缸内燃烧计算,分析了缸内流场和油气混合情况.分析表明:缸内流场方面,在压缩冲程中不同工况下均形成了非常明显的滚流流场,同时滚流比大小的变化存在明显的"双峰"现象,不同工况下均有燃油...     

Measuring the tribological performance of all the tappets in a production engine using magnetometer sensors and the effect of lubricant rheology

Tappet rotation is one of the key tribological parameters that play an important role in component wear. Lack of available techniques has discouraged researchers from performing such studies on real production engines. In this research work, a novel experimental technique has been developed that allows the measurement of tappet rotation speed on any engine having direct acting tappets. This unique method does not require any changes or modifications to the components or engine itself. Using this innovative technique, for the first time, all the tappets of a single camshaft have been instrumented, and tappet speed was measured at different operating conditions verifying that not all the tappets behave in the same way. Experimental results clearly showed that all tappets do not respond to the change in lubricant viscosity and the direction of tappet rotation may be one of the factors influencing the performance. Copyright © 2014 John Wiley & Sons, Ltd.     

铸造工艺在发动机核心零部件的应用——以奔驰和沃尔沃发动机国产化为例

以正在国产的新型直列4缸汽油发动机奔驰M274/270和沃尔沃VEP4之曲轴、凸轮轴、缸体和缸盖为研究对象,分析铸造工艺在发动机核心零部件的应用。壳模铸造球墨铸铁曲轴性能达到锻造曲轴水平,可大力推行以铸代锻;壳模铸造激冷低合金铸铁空心凸轮轴量产条件成熟并仍将占具较大市场份额;高压铸造铝合金缸体和重力铸造铝合金缸盖是主流成熟技术,具备大力推行条件。     

Steady-flow characteristics and its influence on spray for direct injection diesel engine

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of Dl (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70ΰ and 90ΰ. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.     

非接触式缸盖平面度误差检测方法与测量系统研究*

为解决发动机缸盖生产铸造过程中缸盖底面平整度误差检测问题,设计一种激光非接触式发动机缸盖底面平整度在线检测系统,提出一种基于对角中线的平面度误差检测算法。根据现场平面度检测需求,设计利用激光臂纵轴和缸盖横轴传送的交互运动的发动机缸盖表面平面度误差检测系统;通过发动机缸盖表面检测四个顶角特征点对角线中线建立发动机缸盖平面度检测的数学模型,利用回归方程确定最小二乘法平面为理想平面,求出平面度误差;并对激光位移传感器进行精度标定,给出传感器误差标定回归方程,并应用该检测系统完成对不同型号的发动机缸盖检测。结果表明：该系统最大检测面积为400 mm×2 000 mm,测量范围为160~450 mm,测量精度为0.03 mm,而且结构简单,检测速度快,完全能够达到在线检测要求。     

大型柴油机关键孔加工技术的研究与应用

介绍了在无专用机床设备的条件下,通过利用传统设备以及自主设计制造专用刀具,实现大型柴油气缸盖凸轮轴孔的加工,解决凸轮轴孔的同轴度问题,同时将该加工方法推广应用到大型气缸体主轴孔加工领域中。     

某柴油机进气道数值模拟及试验研究

采用基于AVL Fire软件的模拟分析方法和基于涡流动量计的试验方法,对某型柴油机进气道的性能进行研究,得到5个工况点下气道的流量系数和涡流比。结果表明:模拟分析可以得到准确的流量系数和平均流量系数、涡流比和平均涡流比。在气道的开发过程中,模拟分析可以替代气道试验。     

A study on the deposit formation in the cylinder and intake valve of a S. I. Engine

A spark ignition engine with port fuel injection (P.F.I.) system was used to accumulate cylinder head deposit (C.H.D.), intake valve deposit (I.V.D.), and piston top deposit (P.T.D.) on an engine dynamometer. In this study, the effect of base gasoline on I.V.D. was examined. The deposit forming tendency and the influence of the fuel component for decreasing deposits have been experimentally examined. The amount of I.V.D. has been observed to increase linearly with the engine operating time. It is also observed that the amount of valve deposit with newly blended gasoline is less than that with base gasoline.     

基于实车状态的发动机均值模型研究

基于实车状态下发动机的测试运行参数，提出了一种改进发动机均值模型仿真精度的方法。首先基于五电机台架对实车搭载环境下的一款自然吸气发动机进行了性能测试，分别获得发动机水温、发动机转速、发动机缸内压力、进气道压力和温度、进气歧管压力和温度、燃油体积流量、发动机飞轮端扭矩、排气歧管压力和温度、排气歧管过量空气系数、三元催化后排气压力和温度等参数；然后运用Amesim/MATLAB软件联合仿真对发动机进行了基于实车搭载环境边界下的数值建模和模型标定。研究结果表明，标定后的发动机均值模型预测结果与实际测试结果最大差值可以控制在8%以内。     

球轴承对凸轮轴摩擦力的影响研究

在可预见的将来,内燃机仍然是主要的汽车驱动力来源。随着油耗法规的不断严苛,持续提升内燃机热效率十分必要,发动机减摩是降低油耗提高热效率的主要途径之一,其中,凸轮轴采用球轴承替代滑动轴承是发动机减摩的重要研究方向。本文以我司1.5T直列4缸发动机为研究对象,通过改变凸轮轴头端轴承类型来研究球轴承对凸轮轴转动摩擦力的影响,实验结果表明,加装球轴承后,凸轮轴的转动扭矩在低速工况下有一定的改善,中高速工况滑动轴承摩擦力更小。     

Experimental study on axial stratification process and its effects (I)-Stratification in Engine-

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an SI engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swirl and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.     

Seal-Inlet Disturbance Boundary Condition Correlations for Rotordynamics Models,Part 1: Correlation Development

Systematic parametric studies were performed to better understand seal-inlet rotordynamics. A CFD-perturbation model was employed to compute the seal-inlet flow disturbance quantities. Seal inlet disturbance boundary condition correlations were proposed from the computed seal-inlet quantities using the important parameters. It was found that the cosine component of the seal-inlet swirl velocity disturbance W _1C has a substantial impact on cross-coupled stiffness, and that the correlations for W _1C and W _1S should be used to replace the historical guess that seal inlet W _1C = 0 and W _1S = 0. Also, an extremely precise relationship was found between the cross-coupled stiffness and the seal-inlet swirl velocity (ω R _sh ?[Wbar] ₀ ). Thus, the number of experiments or computer runs needed to determine the effect of spin speed, shaft radius, and/or inlet swirl velocity on cross-coupled stiffness could be greatly reduced by plotting the simplified relationship of the cross-coupled stiffness against the swirl slip velocity. In addition, the upstream chamber size and shape were found to have a substantial influence on the seal-inlet swirl disturbance velocity W _1S which plays a significant role in determining the direct stiffness.