多孔介质发动机详细反应动力学模型

应用Chemkin化学动力学软件包中的Senkin模块模拟了正庚烷在多孔介质发动机中的燃烧过程．通过修改Senkin程序,结合了Woschni传热模型和多孔介质换热模型,并在正庚烷详细氧化机理中加入氮氧化物的生成机理,将此程序纳入发动机燃烧的零维单区模型．对多种工况参数进行计算,讨论了运行参数对发动机性能的影响．当进气温度、压缩比增大,或过量空气系数降低时,多孔介质发动机着火时刻会明显提前．结果表明：多孔介质对混合气具有预热作用可强化发动机的点火燃烧,多孔介质的初始温度是决定压燃点火的决定性因素．     

Experimental study on premix combustion at isosceles triangle type rate of heat release for squish type combustion chamber

This paper presents a theory on premix fuel combustion at near isoceles triangle type rate of heat release, describes the measures taken for the combustion system, points out its many theoretical advantages, and that it can solve effectively the problems of rough running, fuel consumption and exhaust emission. Two squish lip type combustion chambers are designed to match separately with multiple holes injector and conical spray type injector in order to achieve premix combustion at near isosceles triangle type rate of heat release. Experimental studies on two single cylinder diesel engines showed that premix combustion at isosceles triangle type rate of heat release resulted in longer ignition delay period, larger amount of fuel injected into cylinder during the ignition delay period, lower maximum pressure, better fuel economy, and better exhaust emission.     

EXPERIMENTAL STUDY ON PREMIX COMBUSTION AT ISOSCELES TRIANGLE TYPE RATE OF HEAT RELEASE FOR SQUISH TYPE COMBUSTION CHAMBER

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Mixture preparation and combustion of CNG low-pressure compound direct injection spark-ignited engines

A set of compressed natural gas (CNG) multi-point direct injection system of spark-ignited engines and the corresponding measurement and data acquisition systems were developed in this paper. Based on different injection modes, the mixture formation and combustion of CNG low-pressure direct injection (LPDI) engines were studied under varying factors such as air/ fuel ratio, injection timing. Meanwhile, three-dimensional simulations were adopted to explain the mixture formation mechanisms of CNG low-pressure compound direct injection (LPCDI) mode. On the basis of test results and simulation of the mixture homogeneous degree, the conception of injection window was proposed, and the LPCDI mode was proved to be more beneficial to the mixture concentration stratification formation in cylinder under lean-burning conditions, which resulted in effective combustion and stability.     

明渠分层湍流的动力学亚格子模型大涡模拟研究

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Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine

In order to predict and improve the performance of natural gas/diesel dual fuel engine (DFE), a combustion rate model based on forward neural network was built to study the combustion process of the DFE. The effect of the operating parameters on combustion rate was also studied by means of this model. The study showed that the predicted results were good agreement with the experimental data. It was proved that the developed combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine. Project supported by National Lab. for Automotive Engine and Safety, Tsinghua University, China     

Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine

ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｔｈｅｗｏｒｌｄｆａｃｉｎｇｓｅｒｉｏｕｓｐｏｌｌｕｔｉｏｎｏｆｅｎ ｖｉｒｏｎｍｅｎｔａｎｄｉｎｅｖｉｔａｂｌｅｄｅｃｌｉｎｉｎｇｒｅｓｏｕｒｃｅｓｏｆｅｎｅｒｇｙ,ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｌｏｗｅｒｐｏｌｌｕｔｉｏｎａｎｄｌｏｗｅｒｅｎｅｒｇｙｃｏｎｓｕｍｐｔｉｏｎａｕｔｏｍｏｂｉｌｅｈａｓｂｅ ｃｏｍｅａｍａｊｏｒｒｅｓｅａｒｃｈｔａｒｇｅｔ.Ｔｈｅｈｉｇｈｅｆｆｉｃｉｅｎ ｃｙａｎｄｌｏｗｐｏｌｌｕｔｉｏｎｎａｔｕｒａｌｇａｓ ｄｉｅｓｅｌｄｕａｌｆｕｅ…     

Evaporate prediction and compensation of intake port wall-wetting fuel film for spark ignition engines fueled with ethanol-gasoline blends

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.     

柴油机高压电控燃油共轨系统研究

目前汽车广泛使用的电控柴油机高压共轨系统由燃油泵总成和共轨管总成构成,柴油机高压电控燃油共轨技术改善了现代柴油机的许多功能。     

Dynamic Wave Pressures on Deeply Embedded Large Cylindrical Structures due to Random Waves

The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil asnd structure.In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves,and accordingly to offer valuable findings for engineering ,the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different cembedment depths in response to two wave spectra ,The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain,By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder,experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory ,and detailed comparisons were also carried out between the single and continuous cylinders ,Some new findings and the corresponding analysis are reported in present paoer,The investigation on continuous cylinders will be used in particular for reference in engineering applications becaus information is scarce on studying such kind of problem both analytically and experimentally.     

Knock prediction for dual fuel engines by using a simplified combustion model

INTRODUCTIONDuetodwindlingfueloilreservesandthedesireforreducedpollutantemissions,naturalgas,whichisdominantlycomposedofmethane,hasbeennowwidelyusedasanalternativefuelininternalcombustionengines .Aconventionaldieselenginecanbeconvertedwithoutexcessiveincr…     

一种面光源的获得方法及其均匀性研究

建立了以圆柱反射取得面光源的模型,并对其均匀性作了详尽的分析,证明了点光源发出的光经柱面反射到达另一端口时,近似形成一个光强分布均匀的面光源．其均匀性与圆柱各参数有关．     

Knock prediction for dual fuel engines by using a simplified combustion model

The present work used a methane-air mixture chemical kinetics scheme consisting of 119 elementary reaction steps and 41 chemical species to develop a simplified combustion model for prediction of the knock in dual fuel engines. Calculated values by the model for natural gas operation showed good agreement with corresponding experimental values over a broad range of operating conditions. Project (No. 50106014) supported by the National Natural Science Foundation of China     

汽油机电控系统原理实物演示装置开发

采用量产电控汽油机上的传感器、控制器和执行器，开发了一套用于演示汽油机电控系统工作原理和过程的实验教学装置。该装置可模拟并演示电控汽油机的喷油、点火、加速、减速、怠速、碳罐等控制过程，简洁、直观、可操作性强，对学生掌握汽油机电控系统的组成和功能起到了积极作用。     

基于Matlab的摩托车发动机单向阀设计

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.     

液化石油气发动机燃料供给系统的设计方案与性能比较研究

液化石油气(LPG)发动机燃料供给系统已经历了三个发展阶段,国外已开发出第三代产品。将三代LPG发动机燃料供给系统的设计方案作了简要介绍,并对其性能作了比较分析,从中可了解国外LPG发动机燃料供给系统的发展历程以及各阶段的技术关键,供国内同行参考。     

Solar Village—Educational Initiative for Kids

Energy use in a human community increases to a great extent where these are of a natural population increase. On another hand, technology advances very fast and fuel has an important role in the technological society. Air pollution during burning fuel to create energy forces the human community to look for a new source of energy. The new source must not be finite and must not make air pollution. This source is solar energy. In this educational initiative a model of a solar village, which uses only solar energy, is built. This project turns the school into an agreeable place and makes pupils like to come to it.     

多台室外空冷冷凝器间的气流扰动研究

为了达到高效的制冷与制热效果,通过建立以多孔介质渗流力学为基础的计算流体动力学模型（CFD）来研究室外机与环境空气的换热过程,以获得室外机的合理布置方式;同时在实验室建立等尺度的室外机物理模型进行测试,获得了比较吻合的速度和温度分布结果,验证了CFD模拟方法的准确性.然后应用数值模拟方法分析不同布置方案下室外机的进风温度,优化了实际工程中3台室外机成直线布置时的合理间距：相邻2台机组之间的最小距离须大于0.2m,机组主要进风侧面与其周围高于机组的竖直墙面的极限间距为0.8m;风机动力相差较大的室外机相邻布置时,其中风机压差较大的室外机不会影响其他机组的进风量和换热量.     

Independent volume-in and volume-out control of an open circuit pump-controlled asymmetric cylinder system

To avoid the flow asymmetry of a closed circuit pump-controlled asymmetric cylinder system, an efficient open circuit pump-controlled asymmetric cylinder system (OPACS) with an independent displacement volume-in and volume-out (VIVO) control method is proposed. The energy transmission path of the OPACS was analyzed, and an energy calculation model was built. A position-pressure combined control method was adopted to validate the proposed OPACS. Based on a 0.6-MN open circuit pump-controlled forging press system, a series of experiments with different return cylinder pressures were conducted. The experimental results confirmed that the proposed OPACS with the position-pressure combined control method was able to recover energy to reduce the installment power without sensitivity to the return cylinder’s pressure variation and that the position accuracy and rapidity could be improved by increasing the pressure in the return cylinder.     

天然气/柴油双燃料发动机电控技术研究

天然气作为燃料具有低排放、低消耗的优点,天然气/柴油双燃料发动机通过应用电控喷气技术,可以实现较高的发动机综合性能.本文系统介绍双燃料发动机电控系统的结构及特性等.