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首页> 外文期刊>International journal of engine research >Measurements of fuel adhesion on cylinder walls and fuel wall-flow behavior with post diesel fuel injections
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Measurements of fuel adhesion on cylinder walls and fuel wall-flow behavior with post diesel fuel injections

机译:圆柱墙上的燃料粘附的测量和柴油燃料喷射后燃料壁流动行为

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摘要

Post fuel injection in the expansion stroke is used for diesel particulate filter regeneration; however, fuel spray impinges on the cylinder liner due to the low temperature and pressure conditions. Fuel adhesion and fuel flowing down across the cylinder liner, the so-called "wall-flow," was observed by high-speed video images, and this adhesion is a cause of diesel engine lubricant oil dilution and the deterioration of fuel consumption in diesel engines. In this article, the fuel adhesion and the wall-flow of post diesel fuel injections were investigated with a high pressure-temperature constant volume optical chamber. The in-cylinder temperatures and pressures at 30, 60, and 90 degrees CA ATDCs, conditions commonly employed in post fuel injection timings, were measured by an actual engine, and similar conditions were created in the constant volume chamber by the combustion of a pre-mixed gas of ethylene, oxygen, and nitrogen. Fuel masses of 0.6, 1.1, and 1.7 mg per hole were injected at each ATDC setting. The weight of the adhered fuel on the wall and the fuel in the piston-cylinder crevice were measured by precision balance, and the liquid-vapor phases in the spray were observed by Mie scattering and shadowgraph methods. To measure the thickness of the adhered fuel on the cylinder wall, the laser-induced fluorescence method was employed. The results show that the fuel spray penetration and adhesion on the cylinder wall were different in the test conditions investigated here. With the early post injection, most of the injected fuel vaporizes without penetrating to the cylinder liner and gaseous diesel fuel is condensed on the cylinder wall. A thin and widely spread out fuel film is formed on the cylinder wall; however, no wall-flow could be confirmed by the high-speed video images. With late post fuel injections, the strong penetration of liquid fuel reaches the cylinder wall, and a thick and widely spread out fuel film was formed on the cylinder wall and the wall-flow phenomenon was observed here. However, the quantity of fuel involved in the wall-flow was smaller than that of the fuel adhering to the cylinder wall. The effects of in-cylinder pressure and temperature on the fuel adhesion on the cylinder wall were investigated. With the increase in pressure and temperature, the quantity of adhering fuel was reduced, suggesting that the boost pressure increase by turbo charging and a higher engine load is effective to reduce fuel adhesion. Furthermore, the effects of multiple post fuel injections on fuel adhesion to the cylinder wall were investigated, maintaining the total fuel injection amounts. With increases in the number of fuel injections, the total percentage of adhering post fuel on the cylinder wall was reduced. In the multiple fuel injections, it was observed that fuel motion takes place during the spray pass after the first and second fuel injections and that the penetration length of the second and third fuel sprays increases.
机译:膨胀行程中的后燃料喷射用于柴油颗粒过滤器再生;然而,由于低温和压力条件,燃料喷雾撞击气缸衬里。通过高速视频图像观察到圆柱衬垫横跨气缸衬套流动的燃料粘附和燃料,这种粘附性是柴油发动机润滑油稀释和柴油燃料消耗劣化的原因引擎。在本文中,利用高压 - 温度恒定体积光学室研究了燃料粘附和后柴油燃料喷射的壁流。 30,60和90度CA ATDC的缸内温度和压力,通常用于后燃料喷射定时的条件,通过实际发动机测量,并且通过预先燃烧在恒定体积室中产生类似的条件 - 乙烯,氧气和氮气的混合气体。每孔0.6,1.1和1.7mg的燃料质量被注入每个ATDC设置。通过精确的平衡测量壁上的粘附燃料和活塞 - 缸缝隙中的燃料的重量,并通过MIE散射和影子图方法观察喷雾中的液态蒸气相。为了测量汽缸壁上的粘附燃料的厚度,采用激光诱导的荧光法。结果表明,在此研究的试验条件下,汽缸壁上的燃料喷射渗透和粘附性不同。利用早期后注射,大部分注入的燃料蒸发而不渗透到汽缸衬里,气体柴油燃料冷凝在汽缸壁上。在气缸壁上形成薄而广泛的燃料膜;然而,高速视频图像可以确认壁流。随着后期燃料喷射,液体燃料的强渗透到汽缸壁,并且在气缸壁上形成厚而广泛的燃料薄膜,这里观察到壁流现象。然而,壁流中涉及的燃料量小于粘附到汽缸壁的燃料的量。研究了气缸压力和温度对汽缸壁上燃料粘附的影响。随着压力和温度的增加,粘附燃料的量减少,表明通过涡轮增压和更高发动机负荷的增压增加是有效降低燃料粘附的有效。此外,研究了多个燃料喷射对汽缸壁的燃料粘附的影响,维持总燃料喷射量。随着燃料喷射的数量的增加,减少了圆柱壁上粘附燃料的总百分比。在多种燃料喷射中,观察到在第一和第二燃料喷射之后在喷雾剂期间发生燃料运动,并且第二和第三燃料喷雾的穿透长度增加。

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