【作者】

Beat von Rotz

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC世界大会上发表，论文的版权归CIMAC所有。 The further development and optimization of the combustion systems of large marine diesel engines is a key element to meet the up-coming emission targets imposed by legislation as well as the increase in efficiency to attend the demands of the seaborne freight transportation market. In this context, the in-depth knowledge of the in-cylinder processes has to be seen as a prerequisite to the technology development work. Therefore, a unique optical accessible experimental test setup – the so-called Spray Combustion Chamber (SCC) – for investigating the spray and combustion behaviour under conditions relevant for large marine diesel en-gines has been developed. This facility re-sembles the sheer physical dimensions of large two-stroke engines, the operational characteristics with respect to thermo- and fluid dynamic conditions (including swirl) at start of injection. Moreover, a wide range of fuel quali-ties can be applied via an engine like injection systems. To gain information about the influence of the fuel on the spray characteristics during injection, the evaporation behaviour and the subsequent ignition/combustion, investigations under engine-like conditions have been performed, using adequate and specific measurement techniques. The macroscopic observations of the spray evolution are conducted by means of an advanced “shadow-imaging” (diffused back-illumination technique) for varying fuel qualities, i.e. light fuel oil (LFO) vs. heavy fuel oil (HFO). In particular, the difference in the evaporation behaviour as well as the propaga-tion/interaction of the spray with the swirl flow observed with experiments at inert conditions will be presented and discussed. Next, the ignition (and combustion) char-acteristics are analysed by measuring the flame illumination and OH* - chemiluminescene signals including a simultaneous capturing of shadow-imaging recordings. Hence, yielding to information about ignition delay as well as ignition (and lift-off) location at a chamber condition (pressure, temperature) representative for large 2-stroke marine diesel engines. For comparison reasons, these data are put into relation with the conditions found in the fuel ignition analyser (FIA). For an in-depth investigation of the subsequent combustion, the heat release rate has been assessed by using an appropriate calculation based on the in-cylinder pressure trace analysis. Here, a variation of three different fuel qualities (on LFO and two qualities of HFO) at different temperature and pressure conditions were studied. These investigations will provide a better in-sight into the special characteristics of the spray formation and combustion behaviour imposed by the peripheral injection into a swirling flow inside the combustion chamber. Moreover, due to the fuel flexible operation of such engines, an emphasis on the fuel quality (varying thermophysical properties) influences with regard to the injection/fuel spray evolution as well as the ignition/combustion behaviour shall extend knowledge on the involved injection and combustion processes. Finally, allowing the optimization of en-gine performance related needs and technologies as well as the development and validation of suitable calculation and simulation methodologies.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

3

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