Investigations on injection-rate oscillations in Common-Rail Injectors for high-pressure injection
In recent studies the possibility of emission reduction through high-pressure fuel injection was shown, 11, 13. By changing the nozzle configuration (number of holes, hole diameter and conicity of the holes) it is possible to reach very low emission levels by using high rail pressures (approx. 3000bar and above). For that investigations different nozzles with different configuration were manufactured and investigated. The huge potential for the reduction of emissions was presented in 6 and 11. However, changing the nozzle design changes the hydraulical behaviour of the injector. With decreasing diameter of the nozzle holes (down to 91 m) certain oscillation effects start to occur which are amplified with increasing rail pressure, 12. These effects can be observed in injection rate measurements and apparently have a positive effect on the combustion process. The description, characterization and the impact of these injection rate oscillations are the main focus of this study. The research focuses on experimental investigations with modern techniques. For that the injection rate of different injectors will be investigated. It can be shown, that for different nozzle configurations the injection rate either show chattering and instability effect or not. The nozzles with distinct oscillations will be investigated in an optical high-pressure vessel. A high-speed camera will be used to observe which impact the changed hydraulic behaviour has on the spray pattern. For this investigation a high-speed Mie Scattering Technique will be used. In order to get the a better understanding of this effect and the impact on the spray pattern additionally a long distance microscope will be used for the investigations of the near nozzle field. With the long distance microscope it is possible to zoom to the nozzle hole outlet and investigate whether needle chattering has an effect on the fuel atomization or not. The study will close with an outlook on on-going research, especially a possibility to calculate the effects with coupled CFD and 1D-hydraulic simulation methods.
Johann A. Wloka Florian Schwarzmueller Georg Wachtmeister
Technische Universitaet Muenchen,Germany
国际会议
上海
英文
1-13
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）