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Experimental Investigation of Intake Diesel Aerosol Fuel Homogeneous Charge Compression Ignition (HCCI) Engine Combustion and Emissions

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Energy and Power Engineering 2014年第14期6卷 513-526页

作者： medhat elkelawy Department of Mechanical Power Engineering Tanta University Tanta Egypt

External mixture formation (PFI) of a diesel fuel aerosol has employed to investigate the diesel HCCI engine combustion and emissions characteristics. The key to the external mixture formation with diesel fuel is the proper fuel/air mixture preparation. A proposed intake diesel fuel aerosol system mainly consists of a small chamber, in which the diesel fuel is fully vaporized by means of fuel cavitation inside the diesel injector nozzle. Nozzle cavitation is mainly affected by the injection pressure and the fuel system temperature. Results obtained reveal that the proposed method determines the possibility of producing a complete homogeneous fuel/air mixture, which can be applied to the diesel HCCI engine. With this method, the combustion and emission behavior were entirely optimized and the engine is capable of running in HCCI combustion mode with nearly ideal mixture preparation. In the present investigation, a methodology for the HCCI combustion mode of the diesel aerosol/air mixtures based on the fuel cavitation inside the injector nozzle parameters (such as the injection pressure and the fuel system temperature where fuel premixed ratio, NOx, CO, CO2, and HC emissions) have analyzed. Based on the engine performance and emissions characteristics the fuel injection pressure and the fuel system temperature have optimized to produce a suitable fuel premixed ratio and the perfect fuel/air mixture homogeneity at different engine operating conditions. The optimal injection pressure ranges between 150 - 200 bars, while the fuel system temperature lies within 175℃ - 200℃. Loops of exhaust gas recirculation (EGR) are used to extend the engine load by controlling the combustion phasing.

关键词： HCCI Cavitation External Mixture Formation Diesel Injector Nozzle EGR

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不同燃料的喷嘴内流动与喷雾形态可视化试验

农业机械学报 2014年第5期45卷 22-29页

作者：姜光军张煜盛 medhat elkelawy 肖干华中科技大学能源与动力工程学院武汉430074 坦塔大学工学院坦塔31111

采用高速可控闪光摄影技术搭建了喷油器喷孔内流动及近场喷雾可视化试验装置,针对柴油、汽油、乙醇柴油、生物柴油4种燃料,对实际尺寸的透明喷油器喷孔内的流动及近场喷雾进行了对比试验研究。试验研究结果表明:所有试验燃料喷孔内均呈... 详细信息

采用高速可控闪光摄影技术搭建了喷油器喷孔内流动及近场喷雾可视化试验装置,针对柴油、汽油、乙醇柴油、生物柴油4种燃料,对实际尺寸的透明喷油器喷孔内的流动及近场喷雾进行了对比试验研究。试验研究结果表明:所有试验燃料喷孔内均呈现空穴流动,低运动粘度、高饱和蒸气压的燃料空穴生成时刻更早、空穴强度更强;喷孔空穴强度较大的燃料具有更大的近场喷雾锥角;喷射结束后喷孔内会产生气体倒流现象并形成初始气泡,初始气泡体积随燃料表面张力的减小而增大。同时发现,针阀运动会对压力室和喷孔内的流动产生极大的扰动并影响其流动形态。

关键词：喷孔流动空穴近场喷雾可视化试验

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背压对喷油嘴断油过程中气体倒流现象的影响

农业机械学报 2017年第10期48卷 364-369页

作者：文华王晨亮 medhat elkelawy 姜光军南昌大学机电工程学院南昌330031 坦塔大学工学院坦塔31111

基于流体体积(VOF)模型和动态重叠网格技术对针阀关闭过程的喷油嘴内流场进行了瞬态模拟,分析发现在断油过程中,喷油嘴压力室和喷孔入口两个位置都会发生空化现象,与试验现象一致。计算得到的最大空化体积与倒流气体体积基本相等,说明... 详细信息

基于流体体积(VOF)模型和动态重叠网格技术对针阀关闭过程的喷油嘴内流场进行了瞬态模拟,分析发现在断油过程中,喷油嘴压力室和喷孔入口两个位置都会发生空化现象,与试验现象一致。计算得到的最大空化体积与倒流气体体积基本相等,说明空化溃灭是造成外部气体倒流的主要原因。压力室内的空化溃灭是引起倒流气体进一步流入压力室的必要条件。进一步从理论推导出新的变量——空化数,用以评估针阀关闭过程喷嘴内空化的程度,得出背压增大,断油过程的空化程度减弱,使倒流的气体体积减少,较好地解释了背压对气体倒流的影响规律。

关键词：气体倒流喷油嘴数值模拟可视化试验背压空化

DME闪急沸腾喷雾特性的试验与数值模拟研究

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内燃机工程 2009年第3期30卷 45-50页

作者：余敬周张煜盛 medhat elkelawy 张辉亚华中科技大学能源与动力工程学院武汉430074

在压力定容室内,利用数字粒子图像速度场仪(DPIV)对二甲醚(DME)闪急沸腾喷雾特性,以及DME和柴油的常规喷雾特性开展了试验研究;建立了适用于DME闪急沸腾喷雾的宏观现象学模型,并将该模型与KIVA程序相耦合,藉此对DME闪急沸腾喷雾特性进... 详细信息

在压力定容室内,利用数字粒子图像速度场仪(DPIV)对二甲醚(DME)闪急沸腾喷雾特性,以及DME和柴油的常规喷雾特性开展了试验研究;建立了适用于DME闪急沸腾喷雾的宏观现象学模型,并将该模型与KIVA程序相耦合,藉此对DME闪急沸腾喷雾特性进行了数值模拟。研究结果表明:与柴油常规喷雾相比,DME闪急沸腾喷雾贯穿距较短,但喷雾锥角较大;喷雾初始段的计算值与试验测量值吻合较好,但喷雾后期的吻合程度稍差。计算研究表明:DME闪急沸腾喷雾体前端两侧存在着明显的涡环结构,喷雾场中DME的气相浓度大幅度高于柴油喷雾的气相浓度,且其索特平均直径(SMD)比柴油小得多。

关键词：内燃机二甲醚闪急沸腾喷雾喷雾特性数值模拟

Investigation of the Flow Pattern inside a Diesel Engine Injection Nozzle to Determine the Relationship between Various Flow Parameters and the Occurrence of Cavitation

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Engineering（科研） 2014年第13期6卷 923-935页

作者： Hagar Alm-Eldin Bastawissi medhat elkelawy Department of Mechanical Power Engineering Tanta University Tanta Egypt

In diesel engines the fuel injection system produces the spray, which directly affects the combustion of the fuel, which in turn determines the production of pollutants. In spite of this, the details of this causal relationship remain unclear. There is, however, a lack of quantitative experimental data for determining and visualizing the cavitation inside real size diesel injector nozzle. The present work is devoted to analyze analytically the flow pattern inside the nozzle of a diesel engine working with hydrocarbon fuel (Diesel fuel) and to predict the relationship between the various flow parameters and occurrence of fuel cavitation in such nozzles. Basic physical parameters affecting this phenomenon are identified and quantified while the effect of nozzle geometry, fuel injection pressure, and engine cylinder temperature upon the flow pattern and occurrence of cavitation in such nozzles are assessed. In this study, a commercial computational fluid dynamics (CFD) package (FLUENT-T grid) is used while a computational grid is generated for the real geometry of diesel injector nozzle using (ANSYS). The suitability of the generated computational grid to give reliable results is examined using the suitable procedures and techniques. The results indicated that, cavitation modeling has reached a stage of maturity and it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions. The qualitative distributions and comparison of cavitation inception and distribution as well as flow parameters at the nozzle exit are also studied.

关键词： Diesel Injector Nozzle Computational Fluid Dynamic (CFD) Cavitation

Numerical Study on the Hydrogen Fueled SI Engine Combustion Optimization through a Combined Operation of DI and PFI Strategies

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Energy and Power Engineering 2013年第8期5卷 513-522页

作者： medhat elkelawy Hagar Alm-Eldin Bastawissi Department of Mechanical Power Engineering Tanta University Tanta Egypt

As the practicability of a hydrogen-fueled economy emerges, intermediate technologies would be necessary for the transition between hydrocarbon fueled internal combustion engines and hydrogen powered fuel cells. In the present study, the hydrogen engine efficiency and the load control are the two main parameters that will be improved by using the combined operation of in-cylinder direct fuel injection (DI) and port fuel injection (PFI) strategies to obtain maximum engine power outputs with acceptable efficiency equivalent to gasoline engines. Wide open throttle (WOT) operation has been used to take advantage of the associated increase in engine efficiency, in which the loads have been regulated with mixture richness (qualitative control) instead of volumetric efficiency (quantitative control). The capabilities of a 3D-CFD code have been developed and employed to simulate the whole engine physicochemical process which includes the hydrogen injection through the intake manifold (PFI) and/or the hydrogen DI in the engine compression stroke. Conditions with simulated PFI, PFI + DI and DI have been analyzed to study the effects of mixture preparation behaviors on the hydrogen ignition and its flame propagation inside the engine combustion chamber. Numerically, the CFD code has been intensively validated against experimental engine data which provided remarkable agreement in terms of in-cylinder pressure history evaluation.

关键词： Hydrogen Fuel SI Engine Port Fuel Injection Direct Injection Wide Open Throttle Kiva-3vr2

Solid Particles Injection in Gas Turbulent Channel Flow

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Energy and Power Engineering 2016年第12期8卷 367-388页

作者： Abd Elnaby Kabeel medhat elkelawy Hagar Alm-Eldin Bastawissi Ahmed Mohammed Elbanna Mechanical Power Engineering Department Faculty of Engineering Tanta University Tanta Egypt

This paper represents a review of the recent researches that investigate the behavior of the gas turbulent flow laden with solid particles. The significant parameters that influence the interactions between the both phases, such as particle size, loading ratio and the gas velocity, have been extensively reviewed. Those parameters are presented in dimensionless numbers in which the applicability of studying its effect in terms of all circumstances of the gas turbulent channel flow at different condition is possible. The represented results show that the turbulence degree is proportional to the particle size. It was found that at the most flow conditions even at low mass ratio, the particle shape, density and size significantly alter the turbulence characteristics. However, the results demonstrate that the particle Reynolds number is a vital sign: the turbulence field becomes weaker if particle Reynolds number is lower than the critical limit and vies verse. The gas velocity has a strong effect on the particles settling along the channel flow and as a result, the pressure drop will be affected.

关键词： Two-Phase Flow Particle-Laden Flow Gas-Solid Channel Flow Particle Size Effect

柴油乳化液喷雾闪急沸腾与微爆现象的激光阴影试验研究(英文)

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内燃机学报 2009年第4期27卷 306-313页

作者： medhat elkelawy 张煜盛 Alm El-Din Hagar 余敬周 El Zahaby A M El Shenawy E A Khalil A 华中科技大学能源与动力工程学院湖北武汉430074 Faculty of Engineering Department of Mechanical Engineering Tanta University Egypt

在常压定容室内,应用ND:YAG激光阴影法、高分辨率CCD照相机和粒径分析软件,对不同含水量的柴油乳化液雾油滴的闪急沸腾与微爆现象以及油滴粒径分布进行了试验测量与变参数对比分析,探讨了在130℃温度条件下,乳化油含水量对乳化油喷雾液... 详细信息

在常压定容室内,应用ND:YAG激光阴影法、高分辨率CCD照相机和粒径分析软件,对不同含水量的柴油乳化液雾油滴的闪急沸腾与微爆现象以及油滴粒径分布进行了试验测量与变参数对比分析,探讨了在130℃温度条件下,乳化油含水量对乳化油喷雾液滴闪急沸腾和微爆的影响,揭示了微爆效应在喷雾雾化和液滴碎化中的作用机理。试验结果表明,包覆于油中的水相颗粒受热闪急沸腾所形成的高压蒸气团冲破无水边界层是导致油滴发生微爆和进一步破碎分裂的首要原因;微爆现象随乳化油含水量的增高而趋强;喷雾索特平均直径(SMD)的细化率随乳化油含水量和喷雾贯穿距的增加而增大,且乳化油含水量对喷雾SMD细化率的影响程度也随喷雾贯穿距的增加更加显著。

关键词：微爆闪急沸腾柴油乳化液滴径测量阴影照相