Experimental investigation of nozzle cavitating flow characteristics for diesel and biodiesel fuels

This study was performed to clarify criteria for cavitation inception and the relationship between flow conditions and cavitation flow patterns of diesel and biodiesel fuels. The goal was to analyze the effects of injection conditions and fuel properties on cavitating flow and disintegration phenomena of flow after fuel injection. To accomplish this goal, it was utilized a test nozzle with a cylindrical cross-sectional orifice and a flow visualization system composed of a fuel supply system and an image acquisition system. In order to analyze the rate of flow and injection pressure of the fuel, a flow rate meter and pressure gauge were installed at the entrance of the nozzle. A long distance microscope device equipped with a digital camera and a high resolution ICCD camera were used to acquire flow images of diesel and biodiesel, respectively. The effects of nozzle geometry on the cavitating flow were also investigated. Lastly, a detailed comparison of the nozzle cavitation characteristics of both fuel types was conducted under a variety of fuel injection parameters. The results of this analysis revealed that nozzle cavitation flow could be divided into four regimes: turbulent flow, beginning of cavitation, growth of cavitation, and hydraulic flip. The velocity coefficient of diesel fuel was greatly altered following an increase in flow rate, although for biodiesel, the variation of the velocity coefficient relative to the rate of flow was mostly constant. The cavitation number decreased gradually with an increase in the Reynolds number and Weber number, and the discharge coefficient was nearly equal to one, regardless of cavitation number. Lastly, it could not observe cavitation growth in the tapered nozzle despite an increase in fuel injection pressure.     

近年来微型计算机主板的简介

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铁路列车到发信息管理系统的研发

列车到发信息管理系统是针对行车指挥发展的新形势研发的.对行车告知板操作进行了统一和规范.介绍该系统研发过程及功能.     

完善我国独立董事制度的思考

公司治理改革已成为当今社会热点.为了防止内部人控制和保护中小投资者的利益,我们引进了独立董事制度,这使得公司治理更加科学、合理.本文通过对当前我国上市公司的独立董事制度现状的分析,就如何既充分又有效地发挥独立董事制度的积极作用提出了可行的建议.     

客滚桥桥体长度确定及过渡板改造设计

客滚桥是连接客滚船与岸壁的重要设施,与广大旅客生命及财产息息相关。本着经济适用、简单安全可靠、维修方便等原则,确定客滚桥桥体长度和过渡板改造设计。     

公交电子站牌系统分析

结合传统公交电子站牌系统模式,建立一种新型的公交电子站牌系统。它利用短程通信技术——Zigbee,实现车辆与站牌之间的连结,使传统开路的通信方式封闭起来,同时也使公交站牌成为一个路边信标,车辆定位更加准确;其次,它使用一种新型的电子站牌类型——立方电子站牌,使电子站牌占用土地资源更少,显示的信息量更大,合理的布局使其实用性更高;同时,它拥有一套合适的运行方案,此方案使系统的可靠性、容错性、实用性得到增强。     

自密实混凝土工艺在佳木斯大桥加固中的应用

从分析自密实混凝土的主要成份及特点入手,介绍了该工艺在佳木斯松花江公路大桥加固中的试验、应用效果以及为解决大桥加固技术难题起到的作用,阐述了自密实混凝土工艺在解决大桥加固中的重要作用,对工程实践有一定指导作用。     

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卧倒小门止水座板具有隔离闸首与船厢水体的作用,其密封程度将直接影响三峡升船机的安全运行。使用《铁路桥涵设计基本规范》中船舶对墩台撞击力公式计算出一般工况下船舶正面撞击卧倒小门止水座板的等效撞击力,利用Solidworks和ANSYS Workbench软件分别对卧倒小门止水座板进行建模和应变分析,并提出小板封闭和整板封闭两种优化改造方案,并对改造方案的施工工艺难度和结构强度进行对比。结果表明,整板封闭方案为优选方案,适用于现场一般工况。     

高桩码头施工新工艺应用

以某高桩码头为例，针对在恶劣海况条件下海上梁板安装施工效率低、海上搅拌船浇筑混凝土施工成本高等问题，进行了工艺创新，采用架桥机安装预制梁板、泵车上船浇筑混凝土、预制梁采用大理石底胎等新工艺及方法，很好地避免了恶劣海况对预制梁板安装的影响并控制了施工成本。     

汽车空调冷凝器边板与集液管焊接新工艺

针对现有汽车空调冷凝器芯体边板与集液管焊接方式的缺陷,介绍2种改进方案。