Systematic LIF fuel wall film investigation
Systematic LIF fuel wall film investigation
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DOI：
10.1016/j.fuel.2016.01.017
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发表时间：
2016-05
期刊：
影响因子：
7.4
通讯作者：
F. Schulz;W. Samenfink;J. Schmidt;F. Beyrau
中科院分区：
文献类型：
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作者：
F. Schulz;W. Samenfink;J. Schmidt;F. Beyrau
汽油在现代均质操作的DISI发动机中的燃烧可导致烟灰颗粒和未燃烧的碳氢化合物。这些污染物的一个主要来源是由于燃料喷雾撞击到气缸壁或活塞上而导致的燃料壁膜的延迟蒸发，特别是在壁尚未达到操作温度时的预热期间以及在活塞仍然接近喷射器时的早期喷射正时。为了减少废气排放和燃油消耗，必须了解燃油膜的特性。本文提供了不同边界条件对壁膜质量影响的新发现。为了提供恒定和定义的边界条件，在压力容器内进行了测量。为了反映在均匀充气发动机内喷射期间的宽范围的操作条件，改变容器压力、容器温度、轨道压力和喷嘴与壁之间的距离。壁膜图案和质量使用非侵入性的激光诱导荧光法测量。喷雾由标准高压六孔喷嘴产生。异辛烷被用作不发荧光的替代燃料，3-戊酮被添加作为良好表征的荧光示踪剂。结果表明，随着环境温度的升高和喷嘴与壁面距离的增大，壁面油膜质量减小。与一般的假设相反，较高的气缸压力，例如由于涡轮增压，被发现增加燃料沉积。较高的轨压在低气缸压力下没有积极的影响，但在涡轮增压条件下，可以通过增加轨压来减少壁膜质量。
The combustion of gasoline in modern homogeneously operated DISI engines can result in soot particles and unburned hydrocarbons. One major source for these pollutants is the delayed evaporation of fuel wall films resulting from the impingement of the fuel spray onto cylinder walls or the piston, especially during warm-up when the walls have not yet reached operating temperatures and for early injection timings when the piston is still close to the injector. To reduce exhaust emissions and fuel consumption the behaviour of fuel films must be understood. This paper provides new findings of the influence of different boundary conditions on the wall film mass.In order to provide constant and defined boundary conditions, measurements were performed inside a pressure vessel. To reflect the wide range of operating conditions during the injection within an homogeneously charged engine, the vessel pressure, vessel temperature, rail pressure and distance between nozzle and wall were varied. The wall film patterns and masses were measured using the non-invasive method of laser-induced fluorescence. The spray was generated by a standard high-pressure, six-hole nozzle. Iso-octane was used as non-fluorescing surrogate fuel with 3-pentanone added as a well-characterised fluorescence tracer. It was found that with increasing surrounding temperature and increasing distance between nozzle and wall, the wall film mass decreases. Contrary to general assumptions, higher cylinder pressure, e.g. due to turbocharging, was found to increase fuel deposits. Higher rail pressures do not have a positive effect at low cylinder pressures but under turbocharged conditions the wall film mass can be reduced by increasing the rail pressure.