特种V型蒸发式火焰稳定器的低压性能试验研究

飞机高空飞行时,加力燃烧室的进口压力降低,导致燃烧性能恶化,为了研究特种V型蒸发式火焰稳定器的低压性能,在主流速度为90m/s时,分别对压力为0.05MPa、0.06MPa、0.08MPa、0.1 MPa的两相混气点火和火焰稳定特性进行了试验,揭示了该稳定器低压火焰稳定性好,贫、富油熄火范围宽的特点,并通过试验现象和对特种V型蒸发式火焰稳定器结构的分析得出该稳定器的火焰稳定机理。     

特种V型蒸发式火焰稳定器的低压性能试验研究

飞机高空飞行时，加力燃烧室的进口压力降低，导致燃烧性能恶化，为了研究特种V型蒸发式火焰稳定器的低压性能，在主流速度为90m／s时，分别对压力为O．05MPa、0．06MPa、O、08MPa、0．1MPa的两相混气点火和火焰稳定特性进行了试验。揭示了该稳定器低压火焰稳定性好，贫、富油熄火范围宽的特点，并通过试验现象和对特种V型蒸发式火焰稳定器结构的分析得出该稳定器的火焰稳定机理。     

特种V型蒸发式火焰稳定器的总压损失试验研究

研究了特种V型蒸发式火焰稳定器的流阻损失,为了能说明问题选用了其它几种蒸发式稳定器与其作对比试验,从而揭示了在冷态下该种稳定器总压损失的特点.     

特种V型蒸发式火焰稳定器的总压损失试验研究

研究了特种V型蒸发式火焰稳定器的流阻损失 ,为了能说明问题选用了其它几种蒸发式稳定器与其作对比试验 ,从而揭示了在冷态下该种稳定器总压损失的特点。     

蒸发型双腔燃烧室和单管燃烧室排气污染性能的比较

为了探讨蒸发型燃烧室的排气污染性能及其生成特点,本文对两种类型的实用燃烧室——蒸发型双腔燃烧室和单管燃烧室进行了排放试验研究。采用常规测试方法,对贫油条件下两燃烧室排气成分中的氮氧化物(NO_x=NO NO_2)和二氧化碳(CO_2)浓度及燃烧室的燃烧效率进行了测量。结果表明:在实验条件下,蒸发型双腔燃烧室的排气污染性能优于单管燃烧室;前者中的NO_x与T_3~*呈非指数关系,即随T_3~*增加,NO_x的上升速率变小,从而有利于抑制较高温度下NO_x的产生。     

热风洞蒸发型燃烧加热器的设计

为某固体冲压发动机燃烧室地面热风洞试验台设计了一种蒸发型煤油燃烧加热器。根据热风洞试验台对加热器的性能要求,设计了加热器的主要部件,采用一元流法,对加热器的空气流量分配及流程参数进行了数值计算,并对加热器进行了燃烧效率特性和出口温度场均匀度的性能试验。结果表明,所设计的加热器在结构方案、主要部件和总体性能方面基本满足设计要求,具有一定的适用性和工程实用价值。     

蒸发式冷凝器空调系统性能实验

对基于蒸发式冷凝器的空调系统进行了性能测试,结果表明即使在相对湿度较大的运行环境下,空调系统性能系数(COP)仍可达到3.5左右,证明即使在夏热冬暖地区,基于蒸发式冷凝器的空调系统仍具有较好的系统效率;空气湿球温度对蒸发式冷凝器的排热性能影响明显,在测试范围内,当其它控制参数不变时,湿球温度每上升1℃,排热量下降5％左右.本研究还对蒸发式冷凝器及空调系统进行了变工况条件下的性能测试,结果表明随着冷负荷的降低,系统COP和冷凝器能效比均有所下降,但采用变风量的运行控制策略可使系统性能系数提高5％以上.     

钻柱稳定器材料性能及尺寸参数分析

常规的、不可变径的钻柱稳定器现在依然是井斜控制井底钻具组合中不可缺少的组件.但是,国内的相关资料贫乏,结构过于单一.通过对国外资料的综合分析,介绍了稳定器材料性能及尺寸参数,并着重介绍了稳定器所用的非磁性钢.同时,列出了三种套装式稳定器(即二件式、三件式、卡箍固定式)的结构和相关的尺寸参数,以及稳定器螺纹接头特点.这些内容有助于对国外稳定器有一个较全面的了解,也可作为稳定器设计、制造和使用的参考.     

吸气式高超声速技术研究进展

系统总结了中国空气动力研究与发展中心在吸气式高超声速技术研究方面取得的主要进展,包括：试验设备、超燃冲压发动机、数值模拟以及机体／推进一体化飞行器。CARDC经过十多年的努力,建成和改造了三种类型的高焓设备：脉冲式燃烧加热风洞、连续式燃烧加热风洞和电弧风洞。开展了多种尺度的超燃冲压发动机的直连式和自由射流式试验,获得了发动机的基本性能及其随油气比、喷孔位置等的变化规律。通过连续式和脉冲式风洞试验结果对比,表明工作时间大于100ms的脉冲式燃烧设备是开展发动机基本性能研究的经济、高效试验手段。成功研制了三维大规模并行数值模拟软件平台AHL3D并广泛应用于发动机研究。在伽．6m风洞中,完成了1．5m带动力飞行器试验,获得了发动机工作和不工作状态下的飞行器推阻及升力特性。同时提出了地面试验、CFD和飞行试验三者综合研究分析的重要性。     

蒸发式冷凝的应用分析

通过分析对比制冷工艺中几种冷凝方式，指出发展蒸发式冷凝技术对制冷系统节能的重要意义．同时通过分析蒸发式冷凝的换热机理，从试验和实践的基础上提出影响蒸发式冷凝器性能的几个重要因素．     

臭氧对甲烷/空气层流火焰传播速度影响规律

为提高气体机稀薄燃烧时的燃烧性能,解决天然气发动机在稀薄燃烧情况下点火能量高以及火焰传播速度慢的问题,利用强氧化性的臭氧对燃料进行改质,进而提高天然气燃烧性能。通过Chemkin软件研究臭氧添加对甲烷层流火焰传播速度的影响,并对臭氧助燃的化学机理进行数值分析。试验结果表明:添加臭氧后,层流火焰传播速度增加,在稀薄混合气条件下增加量更明显。在不同温度及压力条件下,掺加臭氧均能增加层流火焰传播速度,最大可增加36%。分析表明:掺加臭氧能明显提升自由基及中间产物的生成量,进而提高甲烷层流火焰传播速度。     

燃烧室形状对天然气发动机缸内流动和燃烧过程的影响

结合4102低排放天然气发动机的开发,应用FIRE软件对4102发动机原燃烧室和2种新的燃烧室设计方案(楔形和弧形燃烧室)进行了建模和仿真计算,对比分析了燃烧室形状对缸内流动和燃烧过程的影响。结果表明,弧形燃烧室效果最好,与原燃烧室相比,在点火时火花塞附近气流速度低,初期火焰核心稳定,火焰传播速度快,燃烧持续期短,缸内最高压力比原始燃烧室提高12.7%,有利于提高天然气发动机性能。     

甲烷/空气预混合气在定容燃烧室内的燃烧试验

为研究进气温度、进气压力、当量燃烧比、射流引燃、压燃(自燃)等对甲烷燃烧的影响,以提高点燃式天然气发动机的性能,在定容燃烧室(CVCC)内进行甲烷/空气预混合气的燃烧试验,通过火焰高速摄影和气体压力测量等手段,获取试验结果并进行分析.试验发现,在燃烧室内安装带通孔的横隔板后,有利于加快火焰传播速度、提高燃烧峰值压力和燃烧的稳定性,在某些试验条件下,下燃烧室会出现混合气压燃(自燃)现象.     

Combustion Characteristics of a Single Cylinder Spark Ignition Engine Fueled with Coal Mine Methane

An experimental investigation was conducted on combustion characteristics of a single cylinder spark ignition engine fueled with coal-mine methane (CMM). The CMM was simulated by the compressed nature gas (CNG)/nitrogen blend fuels. The cylinder pressure was measured. The maximum heat release ratio, the flame development duration and the main combustion duration were analyzed with the nitrogen volume fraction in the blends changing from 0% to 35%. The results indicate that the maximum cylinder pressure, the maximum rate of pressure, the flame development duration and the main combustion duration increase and the maximum rate of heat release decreases with increasing nitrogen fraction. When the level of nitrogen volume fraction in coal-mine methane is lower than 20%, the combustion process of engine is stable. But with the level of nitrogen volume fraction over 30%, the cycle to cycle combustion variation is large, especially under low load condition.     

汽油混氢内燃机稀燃性能的仿真研究

在进气混氢体积分数为0、1%、3%和6%的条件下进行了汽油混氢发动机在低速、低负荷以及稀燃时的内燃机台架试验.根据试验得到的不同工况下发动机的缸压、进气流量及平均有效压力等数据对基于AVL Boost软件所建立的汽油混氢内燃机仿真模型进行了标定.利用该模型对相同进气压力、不同混氢体积分数和不同过量空气系数的条件下汽油混氢内燃机的稀燃性能进行了仿真.结果表明,混氢对稀燃时发动机低速、低负荷工况的燃烧过程改善效果较为明显,随着混氢体积分数的增加,稀燃时发动机指示热效率和做功能力均有所提高.相同混氢体积分数下,随着过量空气系数的增大,缸压峰值降低,缸压峰值所对应曲轴转角位置推迟.稀燃时,混氢后发动机火焰发展期和传播期明显缩短,缸压峰值升高且缸压峰值所对应的曲轴转角也有所提前.     

Gasoline-diesel dual fuel intelligent charge compression ignition (ICCI) combustion: Conceptual model and comparison with other advanced combustion modes

The internal combustion engines can remain the advantage over competitor technologies for automotive driven, especially the engine efficiency, exceeded 50% while maintaining ultra-low emissions. In this paper, a novel combustion mode characterized by dual high-pressure common-rail direct injection systems, denoted as intelligent charge compression ignition(ICCI) combustion, is proposed to realize high efficiency and clean combustion in wide engine operating ranges. Specifically, commercial gasoline and diesel, which are considered to be complementary in physical and chemical properties, are directly injected into the cylinder by the two independent injection systems, respectively. Through this unique design, the in-cylinder air-fuel mixtures can be flexibly adjusted by regulating injection timing and duration of different fuels, consequently obtaining suitable combustion phase and heat release rate. The ICCI mode can widely run from indicated mean effective pressure 2 bar to 16 bar with an utterly controllable cylinder pressure rising rate, around 50% indicated thermal efficiency and low NOxemissions. A series of experiments were carried out to compare the combustion and emissions of ICCI with other combustion modes(including conventional diesel combustion, reactivity-controlled compression ignition, partially premixed combustion, and gasoline compression ignition). The results show that at the medium engine loads, ICCI mode can reach much high indicated thermal efficiency, especially up to 52% along with extremely low NOxemissions. Prospectively, ICCI mode can realize real-time adjustments of in-cylinder mixture stratification and instantaneous combustion mode switch in one cycle at any operating conditions, and has an excellent commercial application prospect for energy conservation and environmental improvement.     

柴油机湍流扩散燃烧火焰面分形特性的研究

利用分形几何学的基本原理对柴油机湍流扩散燃烧火焰的表现特性进行了研究,对火焰前锋轮廓线进行了测量和分析,所得结果表明：柴油机中的湍流扩散燃烧火焰面也具有分形特性,从而实现了对扩散燃烧火焰面的定量描述     

缸内燃烧光电测量的可视化技术

利用光纤传感器对内燃机缸内燃烧进行了探测 ,并与以往常规压力传感器的测量结果进行了比较 ,探索了将光纤传感技术应用于燃烧测量的可行性。利用光强信号可实现同步探测燃烧过程的燃烧时刻、爆震燃烧、循环稳定性、火焰传播及成分分析等多项燃烧特征。图像光纤传感器是未来普及与实现燃烧深层次研究的有效手段。燃烧可视化对燃烧过程测量具有重要意义。     

二甲醚发动机低压共轨燃料喷射系统的设计及试验

针对二甲醚燃料低粘性、高蒸汽压以及容易与空气形成混合气的特性,设计了一种可控预混合燃烧的二甲醚发动机低压共轨电控燃油喷射系统.在此基础上,以柴油代替二甲醚进行试验,分析了在喷射持续期,共轨压力、针阀升程和转速对燃油喷射过程的影响,得出了低压共轨燃料系统的燃料喷射特性,对二甲醚低压共轨系统的实用化起到了促进作用.     

Numerical investigations on HCCI engine with increased induction induced swirl and engine speed

Homogeneous charge compression ignition(HCCI) mode of combustion is popularly known for achieving simultaneous reduction of NOx as well as soot emissions as it combines the compression ignition(CI) and spark ignition(SI) engine features. In this work, a CI engine was simulated to work in HCCI mode and was analyzed to study the effect of induction induced swirl under varying speeds using three-zone extended coherent flame combustion model(ECFM-3Z, compression ignition) of STAR-CD. The analysis was done considering speed ranging from 800 to 1600 r/min and swirl ratios from 1 to 4. The present study reveals that ECFM-3Z model has well predicted the performance and emissions of CI engine in HCCI mode. The simulation predicts reduced in-cylinder pressures, temperatures, wall heat transfer losses, and piston work with increase in swirl ratio irrespective of engine speed. Also, simultaneous reduction in CO2 and NOx emissions is realized with higher engine speeds and swirl ratios. Low speeds and swirl ratios are favorable for low CO2 emissions. It is observed that increase in engine speed causes a marginal reduction in in-cylinder pressures and temperatures. Also, higher turbulent energy and velocity magnitude levels are obtained with increase in swirl ratio, indicating efficient combustion necessitating no modifications in combustion chamber design. The investigations reveal a total decrease of 38.68% in CO2 emissions and 12.93% in NOx emissions when the engine speed increases from 800 to 1600 r/min at swirl ratio of 4. Also an increase of 14.16% in net work done is obtained with engine speed increasing from 800 to 1600 r/min at swirl ratio of 1. The simulation indicates that there is a tradeoff observed between the emissions and piston work. It is finally concluded that the HCCI combustion can be regarded as low temperature combustion as there is significant decrease in in-cylinder temperatures and pressures at higher speeds and higher swirl ratios.