共查询到19条相似文献,搜索用时 78 毫秒
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采用三维贴体坐标结构化网格,对复杂曲面形状的新型旋流燃烧器(花瓣燃烧器)进行了三维的流场数值实验.模拟了旋流的衰减过程,分析了花瓣燃烧器的流场特点;首次给出了旋流燃烧器回流区的立体形状图,直观地反映了回流区的特性;分析了普通旋流燃烧器和花瓣燃烧器的流场参数,并对掺混系数进行了对比;通过花瓣燃烧器流场特性的研究得出,花瓣燃烧器的回流区是由径向回流区和中心回流区融合构成,端部呈花瓣状,所形成的特殊流场能够使煤粉颗粒从燃烧器喷入炉内后,不是首先向外扩散,而是迅速地进入回流区,与高温烟气迅速混合,形成稳定热源,为煤粉着火燃烧提供了前提条件,具有良好的稳燃性能. 相似文献
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以一台200 MW旋流式煤粉炉为研究对象,以数值模拟软件FLUENT6.0为计算平台,研究了适合于旋流燃烧方式煤粉炉内流动的数值模拟方法.结果表明,在采用燃烧器和炉膛分别进行网格划分和模拟的基础上,炉膛燃烧器区域为结构化网格模拟的结果伪扩散现象比较小,而且燃烧器区域的空气流场与理论上旋流燃烧器的射流特性相一致,与实验结果相比较,回流区相对长而短些,这主要是由于二次风量的增加以及缺少钝体的作用所引起的,而在定性上,模拟得出的速度场的分布和回流区的趋势符合实验得出的数据结论,由此可见,在模拟过程中所采用的模拟方法适合于旋流燃烧方式锅炉. 相似文献
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钝体形状对旋流燃烧器出口流场影响的数值研究 总被引:3,自引:0,他引:3
借助CFD软件,对配置中心钝体的双通道旋流燃烧器出口流场进行了冷态数值模拟,分别获得了锥型、楔型和抛物线型三种钝体后的流场分布、速度分布、中心回流区尺寸和中心回流量大小等结果.经对比分析发现:在其他条件相同的情况下,非流线形的锥型钝体和楔型钝体与接近流线形的抛物线型钝体相比,中心回流区的长度分别增加了24%和17%;中心最大回流量分别增加了18.3%和6.5%.在将抛物线型钝体燃烧器的旋流二次风量加大50%时,其中心回流区长度虽有所增加,但仍不能达到锥型钝体和楔型钝体的相当程度.研究结果表明:非流线型钝体比流线型钝体具有更大的中心回流区尺寸和回流量;钝体形状是影响出口流场特性的关键因素;与楔型钝体和抛物线型钝体相比,锥型钝体具有更好的稳燃效果.图7表1参7 相似文献
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IntroductionPipelines with non-circular section have beenwidely used in the industrial fields. The inner fiowsbecome more complex compared with those ofcircular section due to production of secondary flows.On the other hand, flows, which pass throughmulhple bends and discharge from fluid machinerysuch as an axial fan and blower and a water turbine,are usually accompanied by a directional swirling.When such swiriing flows discharge into the pipeline,it oscillates and happens to be broken becaus… 相似文献
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基于生物乙醇燃料的贫燃预混、预蒸发燃烧技术(Lean Premixed Pervaporation,LPP),采用数值模拟方法,研究了预混室内生物乙醇雾化蒸发流场,分析了预热空气温度为500、600和1 000 K以及旋流数为0.47、0.8和1.41时的生物乙醇蒸发和气体混合特性的规律。研究表明:在LPP预混室旋流流场中,中心回流区宽度随预混室距离的增加先增大后减小,并且会受喷雾射流的影响拉伸变长,中心回流区随旋流强度的增大更贴近喷雾出口,角回流区的长度随旋流强度增大而缩短直至消失,旋流强度对液雾整体蒸发速率影响不大,但会影响液雾分布;进气温度增加会增大进气速度,提高液滴蒸发速率,缩短液雾炬长度;液滴蒸发过程存在一定程度上的压力振荡,会对LPP不稳定燃烧过程产生一定影响。 相似文献
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《Energy Conversion and Management》2005,46(9-10):1495-1512
In this paper, batch drying of wheat grains in a fluidized bed dryer, which had a swirling flow field in its drying medium, was experimentally investigated. In the experiments, a laboratory scaled fluidized bed type dryer was used. The effects of the swirling flow field on the drying performance were investigated by using an axial guide vane type swirl generator. The effects of the mass flow rate and temperature of the air on the drying performance were also investigated. The goal of this work is to present the experimental results on the drying process of wheat and the effects of the swirling flow field on the drying performance. 相似文献
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This paper presents the results of experiments and numerical simulation of the turbulent swirling flow and heattransfer in a duct.The calculated results are in good agreement with data obtained by measurements.It isfound that the swirling flow promotes heat transfer to the wall of the duct;the swirl numbers are dependentupon the vane exit angles of the swirler,distance from the swirler and the duct Reynolds number.But the decayof swirling flow in streamwise direction is related to local Reynolds numbers and is independent of the swirlerexit angle.The swirl flow characteristics presented in this paper may be used for engineering purposes. 相似文献
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A numerical simulation of swirling turbulent flows of coaxial jets in a combustor is presented in this paper. The new algebraic Reynolds stress model (ASM) is employed for the closure of the time-averaged governing equations for swirling turbulent flows. Two cases of the swirling flow, i.e., a coswirl jet flow and a counterswirl jet flow, are simulated. The calculated results of the axial and tangential velocities, static pressure, and turbulent fluctuating velocity are compared with the measured data for both cases. The results illustrate that the predictions by the new ASM are closer to the measurements than those obtained by the k-epsilon model. 相似文献