船用超长二冲程柴油机单向扫气的经验模型

IF 1.3 4区 工程技术 Q3 ENGINEERING, CIVIL
Yingyuan Wang, J. Gu, Mingyang Yang, K. Deng, Lei Cui, Yuehua Qian
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引用次数: 0

摘要

低速二冲程柴油机由于其燃油经济性和可靠性的优点,在船舶工业中被广泛应用,尤其是在油箱中。然而,随着超长冲程趋势的出现,现有的基于短冲程气缸配置的扫气模型不再适用。在这项研究中,我们使用粒子图像测速和计算流体动力学(CFD)模拟来研究气缸中的流场和残余废气分布。结果表明,清除剂流上游有一个强大的Burgers涡结构,并随着清除剂向下游移动而逐渐消散。此外,根据详细的CFD分析,扫气过程包括三个过程:置换、混合扫气和短路。受研究结果的启发,提出了一个由三个子模型组成的超长行程单流扫气经验模型。具体地,提出了浓度水平和扫气输送比之间的对数关系来描述混合扫气过程。最后,根据CFD结果对模型进行了验证。结果表明,该模型与CFD预测的扫气效率曲线的差异小于1%,从而证明了模型的可靠性。船用低速发动机具有功率范围大、热效率高、油耗低、可靠性好等优点,被广泛用于为民用船舶提供动力(Heywood 1999)。低速发动机市场广阔,通过研究提高低速发动机的性能具有重大的经济和环境意义(Woodyard 2004)。为了满足船东对降低燃料消耗的要求和国际海事组织将新建船舶温室气体排放量减半的规定,低速发动机的超长冲程已成为一种趋势(Lamas&Vidal,2012年)。超长冲程,劣质燃油的燃烧速度较慢,超长冲程气缸可以延长膨胀过程,改善燃烧过程,降低油耗率(风华2014)。超长冲程柴油发动机在原有低油耗的基础上进一步节省了3.5-7%的燃油。以前,由于材料和制造工艺的限制,无法实现超长冲程。然而,近年来,随着材料和工艺的进步,超长笔划已被广泛采用,因为它们显示出优越的竞争力。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Empirical Model of Uniflow Scavenging for Ultra-Long-Two-Stroke Marine Diesel Engines
Low-speed two-stroke diesel engines are widely employed in the marine industry, especially in tanks, owing to their advantages of fuel economy and reliability. However, with the emerging ultra-long-stroke trend, existing scavenging models, which are based on the configuration of cylinders with short strokes, are no longer applicable. In this study, we investigate the flow field and residual exhaust gas distribution in a cylinder using particle image velocimetry and computational fluid dynamics (CFD) simulations. The result shows a strong Burgers vortex structure upstream of the scavenger flow and dissipates gradually as it moves downstream. Furthermore, the scavenging process comprises three processes according to the detailed CFD analysis: displacement, mixing scavenging, and short circuit. Inspired by the results, a tailored empirical model of ultra-long-stroke uniflow scavenging comprising three sub-models is proposed. Specifically, a logarithmic relationship between the concentration level and scavenging deliver ratio is proposed to describe the mixing scavenging process. Finally, the model was validated against CFD results. The results demonstrate that the discrepancy in the scavenging efficiency curve predicted by this model and CFD is less than 1%, thereby demonstrating model reliability. Owing to the advantages of a large power range, high thermal efficiency, low fuel consumption rate, and good reliability, marine low-speed engines are widely used to provide power to civil ships (Heywood 1999). The market for low-speed engines is vast and is improving the performance of low-speed engines through research has great economic and environmental significance (Woodyard 2004). To meet the requirements of ship owners for lower fuel consumption and the IMO’s regulation of halving the greenhouse gas emissions of newly built ships, the ultra-long stroke of low-speed engines has become a trend (Lamas & Vidal 2012). With an ultralong stroke, the combustion speed of low-quality fuel oil is slow, and an ultra-long-stroke cylinder can prolong the expansion process, improve the combustion process, and reduce the fuel consumption rate (Fenghua 2014). The ultra-long-stroke diesel engine further creates fuel savings of 3.5–7% based on the original low fuel consumption. Previously, ultra-long strokes could not be achieved, limited by materials and manufacturing processes. However, in recent years, with the advancement of materials and processes, ultra-long strokes have been widely adopted as they have demonstrated superior competitiveness.
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来源期刊
Journal of Ship Research
Journal of Ship Research 工程技术-工程:海洋
CiteScore
2.80
自引率
0.00%
发文量
12
审稿时长
6 months
期刊介绍: Original and Timely technical papers addressing problems of shipyard techniques and production of merchant and naval ships appear in this quarterly publication. Since its inception, the Journal of Ship Production and Design (formerly the Journal of Ship Production) has been a forum for peer-reviewed, professionally edited papers from academic and industry sources. As such, it has influenced the worldwide development of ship production engineering as a fully qualified professional discipline. The expanded scope seeks papers in additional areas, specifically ship design, including design for production, plus other marine technology topics, such as ship operations, shipping economic, and safety. Each issue contains a well-rounded selection of technical papers relevant to marine professionals.
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