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横向流速度对旋流式喷嘴雾化影响的数值分析 总被引:2,自引:0,他引:2
为了研究横向流速度对旋流式喷嘴雾化的影响,通过对旋流式喷嘴在横向流场中的雾化场进行数值模拟;模拟结果给出了喷雾流场随横向流速度变化的规律,并得到了不同横向流速度下喷雾液滴的索特平均直径(SMD),进一步分析了喷嘴出口下游截面雾化粒径的分布情况。 相似文献
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文章详细介绍了燃油燃烧器高压雾化型喷嘴的基本原理和运行规律,着重分析了燃油的性质和运行工况参数对喷嘴性能的影响。文章同时给出了选择喷嘴的具体建议,具有一定的指导意义。 相似文献
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建立了旋流喷嘴雾化的数值计算模型,将计算结果与静止大气环境下液滴粒径的试验数据进行了对比,证明该数值计算模型的准确性.利用数值计算方法,研究了旋流喷嘴在不同安装角下,喷雾进入横向气流场后液滴Sauter直径(SMD)的变化规律,给出了喷嘴出口下游矩形管道中不同截面上雾化液滴粒径的分布情况.结果表明:对于压力旋流喷嘴,安装角与液滴统计粒径呈多值关系;随着喷嘴安装角的增大,液滴粒径的分布变宽. 相似文献
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在300MW汽轮机喷嘴优化设计中,采用了子午面外轮廓线沿汽道收缩和叶片沿叶高朝转子旋转方向凸出弯曲的两项新技术,并给出了子午面收缩及叶片弯曲的规律。在用全三元势函数程序(文献[1])对西屋喷嘴设计及哈汽厂喷嘴优化设计系统分析后,提出了进一步优化的设想。 相似文献
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张鹏 《小型内燃机与摩托车》2014,(6):26-33
采用高速摄像技术在常温常压状态下对二甲醚闪急沸腾喷雾过程进行了观察,研究了启喷压力和喷孔直径对喷雾形态发展过程、喷雾贯穿距和喷雾锥角的影响。实验结果表明,喷嘴启喷压力越大,涡环形成时间越晚,喷雾锥角越小,喷雾贯穿距越大;喷孔直径越小,涡环形成时间越晚,喷雾锥角越小。喷孔直径对喷雾贯穿距的影响则比较复杂,在喷雾前期,喷孔直径越小,喷雾贯穿距越大,但在喷雾后期,情况正好相反。 相似文献
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油束撞击法形成混合气在涡流室式柴油机上的应用 总被引:3,自引:0,他引:3
介绍了一种头部带挡块的轴针式喷油嘴在涡流室式柴油机上的应用。该喷嘴的特点是喷孔喷出的燃油直接撞击在挡块上,油束经挡块撞击在改变了方向的同时也产生油滴的二次雾化,从而达到既加大喷束与空气的接触面积,同时又限制了燃油喷进燃烧室中心的目的。发动机的台架试验表明,采用这种喷油嘴后,可以显著地改善原机的经济性和排放品质。在柴油机的标定工况下,比油耗和排气烟度分别降低4%和30%。这种混合气形成方法为进一步提高柴油机的性能提供一个新的途径。 相似文献
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燃油碰撞形成混合气在直喷式柴油机上的应用 总被引:2,自引:1,他引:1
介绍一种新型直喷式柴油机燃烧系统。在普通轴针式喷油嘴头部加装一挡块,燃油束经其撞击后,部分燃油向垂直于轴针方向四周扩展,增大燃油与空气的接触面积,加快燃油与空气的混合速率,实现了在较低涡流比条件下用单孔轴针式喷油嘴进行直喷式燃烧。实验在一台卧式单缸柴油机上进行。结果表明,该燃烧系统可行,对燃油品质要求不高、工作可靠、起动性好。 相似文献
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In the steel making industry, high heat fluxes are obtained using effective cooling techniques such as spray impingement cooling. Spray impingement technique involve factors like droplet size, spray height and spray angle, impingement density, and nozzle geometry rendering it very difficult to measure the effects of individual parameters. In the present study, the cooling rate of the plate was experimentally investigated using distilled water as coolant in 3 pressurized nozzles for spray over the surface of the steel plate at elevated temperatures and the behavior of plate temperature with time was tabulated. Cooling curves were generated for different and varying spray parameters like water pressures, nozzle tip to surface distance, and impingement density. It was observed that the cooling rate at the stagnation zone was strongly dependent on the water pressures and nozzle tip to surface distances with maximum cooling rates reaching within 1–2 seconds after the impingement. The average impingement density increased with increase in water pressure and the cooling rate reduces at higher pressures and nozzle tip to surface distances. 相似文献
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A pressure-based procedure to solve problems ranging from incompressible to highly compressible flows is described. The method adopts the fully conservative finite-volume approach, for which the meshes can be of any topology. To handle the sharp change of the gradient in the regions near the shock or the solid wall, the convective flux is limited using high-resolution schemes such as the total variation diminishing (TVD) or the normalized variable diagram (NVD) scheme. The flux limiters are determined from the characteristic variables instead of the commonly used primitive or conservative variables. To enhance solution accuracy, the gradient is calculated using a linear reconstruction approach. The method is assessed and validated via testing on a number of flow problems, including inviscid flows through a convergent-divergent nozzle, inviscid and viscous flows past an airfoil, and viscous flows through a double-throat nozzle. 相似文献
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IntroductionFundamental stUdies of losses in tUrbomachinery in-dicate that, besides giving rise to losses of work, leakageflows contribute to the overall creation of entropy andkinetic encrgy losses. Some entropy is created in thelabyrinth seals and in passages between the fixed androtating pats of turbomachinery. CFD computations inlabyrinth seal geometries enable the evaluation of theentropy ereation PrOCesses there. CFD-based analysis canm1nindze the mass fiow rates of the tip leakage a… 相似文献