【作者】

Simon Matlok

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC大会上发表，论文的版权归CIMAC所有。The fuel nozzle of a Diesel engine can be seen as the interface between the injection system and the combustion chamber and it plays a pivotal role in achieving a fuel-effective combustion with low emissions. The injector is responsible for delivering and distributing the fuel into the combustion chamber, and to achieve good air-fuel mixing. To improve the design of injectors for 2-stroke Diesel engines both experimental and numerical development work has been performed to better understand the role of cavitation inside the fuel nozzles for large two-stroke Diesel engines. A number of experimental rigs have been used to investigate different aspects of the flow and cavitation properties in the fuel injector. A rig utilizing a full size injection system injecting into a standard atmosphere vessel has been used to evaluate the momentum flux produced by individual nozzle holes. This rig can be used to assess to what extent upstream geometrical features in the injector influence the momentum flux of the spray using force measurements. Furthermore an optically accessible rig mimicking the fully open injection valve has been used to measure the fuel velocity field inside the injector together with visualizations of the in-nozzle cavitation, using advanced optical measurement techniques. These techniques encompass microscopic Particle Imaging Velocimetry (PIV) using fluorescing seeding particles as well as Shadowgraph techniques using high spatial resolution with a pulsed laser and high temporal resolution with high speed imaging with frame rates as high as 400.000 frames per second. The rigs have shown to be useful in producing results suitable for the evaluation of Computational Fluid Dynamics models. The computed time averaged in-nozzle velocity fields as well as the prediction of the location of cavitation shows good agreement with the experiments. Furthermore, the predicted loss coefficients of the individual nozzle holes show excellent agreement with experimental results. Finally, visualizations of the near nozzle fuel spray inside a full size two-stoke low-speed test engine have been performed using high speed shadowgraphy with frame rates up to approx. 70.000 frames per second to assess the spray characteristics at engine conditions. The results obtained can be used to increase the understanding of the flow inside injectors and the cavitation produced.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

2

返回