【作者】

Christian Disch,Philipp Huegel

【摘要】

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。Large-bore natural gas engines are a promising technology to meet future demands for ervironment-friendly cogeneration and industrial applications. The challenge to develop ultra-lean mixture combustion processes with the highest thermal efficiency and power output, under terms of lowest level of raw emissions is strongly affected by the capability for a stable and reliable ignition process. The ignition in the main combustion chamber is usualy initiated by flame jets of a gas-scavenged prechamber spark-ignition system. To examine the potential of an increased equivalence ratio level in the main combustion chamber,a detailed knowledge and understanding of the prechamber jet propagation process is essential. An exclusive thermodynamic investigation is not able to show spatial and temporal details of lean mixture combustion processes. For a comprehensive study, the thermodynamic investigations have to be combined with optical measurement techniques. The results presented in this technical paper were carried out using an MAN 32/40 multi-cylinder research gas engine, equipped with a prechamber spark-ignition system. The integration of the endoscopic optics was realized so that design changes were maintained at the lowest possible level. This ensured that the engine could be operated during these optical investiga-tions very much like a corresponding series production variant. The optical access was prepared as a kink-angle arrangement which enables observation of the prechamber jets, beginning with the initial penetration and continuing with the ignition of the lean mixture in the main combustion chamber. An improvement of the lean mixture combustion process requires the detailed observation of the prechamber jet characteristics. This was realized with an endoscopic high-speed camera system in combination with a UV-intensifier, visualizing the chemiluminescence intensity of the flame front propagation. The camera framing rate was set to 9kHz. The measurement setup was used to analyse the characteristics of three different prechamber de-signs.A precise observation of the orifice diameter's influences was arranged in a way so that an individual prechamber jet wasoptically isolated' in the field of view. This arrangement offers a selective detection of an individual prechamber jet. Three different orifice pattern designs with various diameters have been tested. The total cross section area of the orifices was kept constant for all prechamber designs. The tests, performed at various operating points, reveal theprechamber characteristics in the context of jet propagation area, spatial and temporal formation, penetration length, and chemiluminescence signal intensity. In addition, the measurement setup was used to identify and evaluate irregular combustion phenomena occurring before and even during the prechamber jet propa-gation. The results, presented in this technical paper, show exemplarily the potential of high-speed imaging investigations to enhance understanding of prechamber jet ignition characteristics and to be an effective method to help meet the challenge to improve future lean mixture large-bore natural gas engines.

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

返回