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《机械设计》2019,(10)
基于一套经改造的汽柴油混合双燃料发动机系统,在柴油发动机进气道安装汽油喷射系统实现缸内均质的混合气制备,通过上止点直喷柴油控制燃烧相位,通过调整汽柴油比例及EGR比例研究双燃料发动机燃烧性能。研究显示:相比原机,汽柴油比例增大,排气温度降低,当汽柴油比例提高到65%时,呈现出低温燃烧效果,同时降低NOx和碳烟的排放,燃烧持续期缩短,最大压力升高率增大,但是整体燃烧效果更优;从EGR特性及其对缸内燃烧过程和发动机燃烧性能的影响来看,此款双燃料发动机在小负荷时宜采用热EGR,在大负荷时宜采用冷EGR;双燃料发动机进气温度提升对燃油消耗率和碳烟并没有明显影响,而对于NOx来说,进气温度会改善发动机燃烧性能提升缸内燃烧温度,进而NOx排放会出现恶化现象。 相似文献
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以157FMI发动机为研究对象,将其发动机进气道喷射原型尝试性地根据双火花塞位置结构实施缸内直喷技术,通过对比不同点火时刻对缸内燃烧过程的影响进行研究,结果表明:发动机转速为2500r/min,喷油量20mg的情况下,喷油器安装角度设定为55°,随着点火时刻提前,缸内平均压力、温度,压力升高率峰值逐渐增大,且平均压力、温度、压力升高率峰值对应的曲轴转角提前,瞬时放热率峰值出现了先增大后减小的趋势,但峰值相位逐渐提前。研究结果为小型摩托车发动机缸内直喷技术的应用提供了理论指导和参考。 相似文献
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针对某型车用高强化柴油机,研究了进气加湿对NOx、碳烟生成的作用机理及油耗的影响,提出采用进气道喷水的方式对进气加湿,运用仿真软件CONVERGE研究了不同油水比对柴油机缸内燃烧及排放的影响,获得了在特定时刻下NOx和当量比在缸内的分布情况,分析比较了不同油水比对缸内温度及压力的影响情况.结果表明:随着油水比的不断下降... 相似文献
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《机械设计与制造》2017,(9)
为深入研究不同比例调合生物柴油对发动机燃烧特性及颗粒物组分的影响,在一台单缸四冲程发动机上进行了调合生物柴油燃烧及颗粒物排放的试验研究。利用燃烧分析仪研究调合生物柴油对发动机燃烧过程的影响,利用热重分析仪(TGA)、气相色谱/质谱联用仪(GC-MS)研究调合生物柴油对颗粒物热重特性、挥发性有机物(VOCs)质量分数及有机可溶成分(SOF)和多环芳香烃(PAHs)组分的影响规律。研究表明:随着生物柴油掺混比的增加,发动机最高爆发压力及压力升高率峰值增加,压力曲线前移,预混放热率峰值随生物柴油掺混比增加而减小。与B0相比,燃用B20调合生物柴油,最高爆发压力增加了5.59%,对应的曲轴转角提前了3°CA。燃用调合生物柴油后VOCs及SOF组分略有增加,燃用B0、B5、B10及B20后颗粒物中VOCs组分的质量分数分别为12.28%、15.09%、23.06%和26.94%,SOF组分的质量分数分别为29.32%、32.08%、34.26%和35.67%,燃用B20后排放颗粒物中总PAHs降低了10.26%。 相似文献
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通过对目前大型立式管道油泵口环所用材料的分析,针对易损零件口环的材料、工艺结构中存在的问题,提出对泵零件加工、装配工艺及口环结构、材料的改进措施。 相似文献
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基于OPTIMUS的通风机进风口集成优化计算 总被引:1,自引:0,他引:1
利用三维数值模拟的方法,对离心式通风机进风口流场进行了计算分析,运用多学科优化平台软件OPTIMUS,集成流体计算软件对通风机进风口进行了优化计算.结果表明,通风机的进风口形状对其性能有明显影响,在改动较小的情况下,可以显著提高通风机性能. 相似文献
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论述了离心通风机叶轮进口相对涡流的产生及其变化规律。分析了相对涡流与流体预旋及叶轮内流的内在联系。初步探讨了影响相对涡流变化规律的重要因素。 相似文献
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可倾瓦推力轴承中进口压力对热动力润滑性能的影响 总被引:2,自引:0,他引:2
从理论上研究了进口压力对推力轴承热动力润滑性能的影响。进口压力的存在,使油膜厚度增大,油膜内粘性能耗散减少,进油流量增大,温升减低,有利于提高润滑性能,轴承转速愈高,进口压力也就愈大。因此,进口压力是分析研究高速轻载可倾瓦推力轴承热动力轴承热动力润滑性能中的一个不可忽略的重要因素。 相似文献
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HYDRAULICCALCULATIONANDMEASUREMENTOFFLOWFIELDWITHININLETPASSAGEOFLARGEPUMPINGSTATIONHYDRAULICCALCULATIONANDMEASUREMENTOFFLOWF... 相似文献
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本文介绍了密封面作用长度的快速检测装置,此装置适用于发动机中进排气门的在线检测。文章阐述了检具的工作原理和结构特点,并对检测结果作了误差分析,分析表明其测量精度完全能满足需要。 相似文献
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In this paper there are presented the results from measurement of a high-powerful racing combustion engine. These results are obtained by means of the system EwaC, which is operating as the data-recording process. That is such measuring equipment, which is sensing and recording information during the engine current operation under the real conditions and real operational loading. A modular approach to the individual measuring consists in a sequential assembly of the individual components belonging to the engine inlet and exhaust system. An investigation of the individual configuration influences of the both systems is performed by means of the sequential experimental measuring. The measurement of the exhaust pipe was based on the application of tuned racing exhaust system. In order to perform experiments oriented to the inlet system it was developed a new system of the thrust-ejector suction, which enables to solve problems connected with an insufficient feeding of cylinder with a fresh mixture. The pressure of air, which is sucked into the engine, is changed from the atmospheric value to the overpressure level. This phenomenon causes an increasing of the engine power output and torque. According to the gained results was investigated a relation between the newly developed inlet pipe and increasing of the engine torque. Furthermore, the experimentally obtained results are well corresponding with the analytical relations described in the relevant literature. These results can be presented for a wide spectrum of the high-powerful engines because the air inlet system is independent on the engine design and arrangement. The analysed system was successful in the motorbike applications. Thus, taking into consideration the positive results there was registered in the last year as well as the patent application concerning this new design arrangement. 相似文献
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Kristian Tnder 《Tribology International》2001,34(12):987
The new class of bearings recently described by the author has some interesting properties. These bearings generate pressure by an effective wedge or inlet step formed by the local roughness instead of the standard inlet geometries. This means that the micro- rather than macro-geometry in the inlet zone ensures that the flow into the bearing meets less resistance than it does out of the bearing. The first paper presented a simple model, consisting of flat pads of infinite width sliding over a smooth counterface. The roughnesses were in the form of transverse or longitudinal grooves. Load capacity, friction and coefficient of friction were calculated. In the present paper the model is studied further and the normal stiffness and damping coefficients as well as the flow are calculated and compared with values for similar smooth standard shapes. It is seen that the coefficients of the new class of devices may be considerably higher and the flow lower than for similar conventional bearings when the film thicknesses are small. It is concluded that they should find useful applications in many practical devices when a certain film is needed for lubrication purposes, but when leakage should be kept a minimum. Piston rings, high precision bearings and possibly hard disks may be envisaged. 相似文献
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确定旋流器操作参数与结构参数的关系对改善其分离性能是重要的。操作参数主要有进口欧拉准数、进口雷诺准数、压力降以及底流分率。进口欧拉准数能全面体现旋流器的操作特性。通过准确的实验数据在较大尺寸范围内,考察了各种结构尺寸及其他操作参数对进口欧拉准数的影响。拟合确立了进口欧拉准数的最终数学模型。给旋流器的设计、数值模拟提供了准确而可靠的实验依据。 相似文献