新型喷腾旋风炉煤燃烧实验研究

喷腾旋风燃烧是一种基于正交强旋流动原理的新型高效清洁燃煤技术。本文在以前工作的基础上，对炉体结构进行改进，并在改进的模型炉中燃用５ｍｍ以下散煤，进行了燃烧实验研究。用Ｋ型（镍铬－镍铝）铠装热电偶测量了炉内温度分布，用ＣＯＳＡ６０００ＣＤ气体分析仪测量了污染物排放，探讨了底吹风与进煤量，底吹风与１次风、２次风的匹配关系，并进行了效率分析。实验结果表明，改进后的结构更有利于煤的火焰稳定和强化燃烧，可以在小型燃煤炉中实现高效低污染燃烧。研究结果为进一步探讨喷腾旋风燃煤技术的机理并把该技术应用于生产实践提供了技术依据。     

不同入口截面角旋风分离器的分离特性

对常规旋风分离器的进口结构进行了改进:使得旋风分离器的入口具有一定截面角。利用计算流体动力学(CFD)技术对具有不同入口截面角旋风分离器的气相流场进行了数值模拟,比较了不同入口截面角时旋风分离器内部流场结构,并对不同入口截面角旋风分离器的压力损失和分离效率进行了实验研究。结果表明:进口具有一定截面角使得旋风分离器内部流场朝有利于颗粒分离的方向变化,可以有效改善旋风分离器的分离性能。在相同的入口风速下,随着入口截面角的增加,旋风分离器总效率和分级效率增加,而压力损失却减小。综合压力损失和效率随入口截面角的变化趋势,可以看出,在所研究的入口截面角范围,45°应是最佳的选择。     

差异旋风分离器并联的气相流场研究

针对催化裂化三旋中的并联旋风分离器运行中产生的不等压降现象,文章采用FLUENT软件模拟了差异分离器并联后的流场,研究结果表明:差异旋风分离器并联后会出现进气室内气量分配不均,公共灰斗内有明显的窜流返混现象,进而影响并联结构的整体效率。     

循环流化床锅炉旋风分离器的最新发展

分离器是循环流化床锅炉的关键部件之一，其结构形式及布置方式决定了锅炉整体布置的形式和紧凑性。针对大型循环流化床锅炉常用的高温旋风分离器，介绍了国内外循环流化床锅炉旋风分离器的最新发展概况，包括国外的水(汽)冷式旋风分离器、紧凑型方形旋风分离器、内置式旋风分离器以及常规高温旋风分离器结构的最新改进。     

不同排尘结构旋风分离器的分离特性

在欧拉-拉格朗日坐标系中对常规旋风分离器和两个不同直管长度旋风分离器内气固流动特性进行了数值模拟．模拟时气相场采用雷诺应力输运模型,应用随机轨道模型模拟湍流流场中颗粒的运动轨迹,并考虑气固两相之间的双向耦合．给出了不同排尘结构旋风分离器的速度、湍动能分布．对不同排尘结构旋风分离器的分离性能进行了实验研究．结果表明,底部加延长的直管可以使灰斗中气流的速度和湍动能得到较大衰减,能有效防止已分离颗粒的二次扬尘．直管内仍具有一定的分离能力,分级效率实验表明,加直管后旋风分离器分级效率有一定的提高．对于给定的旋风分离器,直管长度应有一最优值．     

旋风分离器自然旋风长的试验研究

采用激光多普勒测速系统(LDV)对φ300mm、升气管直径为De=100、135和180mm的旋风分离器内气相流场进行了测量,主要分析了旋风分离器的自然旋风长。测量结果表明,旋风分离器内的旋转流呈现明显的衰减特性。沿升气管出口轴向向下,切向速度和轴向速度逐渐减小,对于直径100mm升气管,最大切向速度由2.55Vi开始衰减,并且最大切向速度的径向位置由0.28R逐渐向壁面移动,内部的刚性涡逐渐扩大,外部的准自由涡逐渐缩小,最终在轴向5.2D处最大切向速度点接近筒体壁面,准自由涡消失,此位置以下形成完全的刚性涡;对于直径135和180mm升气管,最大切向速度的值和位置也具有相似的变化。在此基础上,提出了旋风分离器自然旋风长的定义,即从升气管下口到准自由涡消失位置的距离为旋风分离器的自然旋风长Lc,依据实验结果给出了计算式(5)的关系式。最后通过分析旋风分离器内旋转流的衰减特性和两涡之间的能量传递过程,进一步说明了旋风分离器自然旋风长的物理意义。     

电旋风除尘技术研究的发展与探索

综述了电除尘技术尤其是电旋风除尘技术的研究进展，分析了目前具有代表性的电旋风除尘器的除尘机理、电极布置型式、旋流方式、结构优化及供电电源类型，提出了加强和完善电旋风除尘技术的几点建议。     

木屑旋风空气分级气化试验研究

基于生物质空气气化机理,结合气流床气化工艺的优点,参考旋风分离器的设计原理,提出了生物质旋风空气分级气化工艺.对不同的位置加入二次风和改变二次风率进行了试验研究.研究结果表明,分级气化能够改善燃气品质.在还原区加入二次风有利于提高燃气热值和气化效率,在氧化区加入二次风有利于减少燃气中焦油的含量.燃气热值、气体产率、气化效率和碳转化率随着二次风率的增加而增加.     

旋风分离器结构改进的研究现状和发展趋势

对工业上普遍应用的颗粒分离设备--旋风分离器结构改进(包括进口、出口、锥体及排尘结构)的研究现状进行了回顾.在此基础上,提出了旋风分离器结构改进的发展趋势,即:由于进口区域和排尘结构对于颗粒的分离至关重要,因此有必要对这部分结构进行深入研究;为了进一步改善旋风分离器的分离性能,除了利用离心力外还需结合其它的除尘机理;为了降低研究成本可以采用计算流体动力学技术来优化旋风分离器结构.     

煤粉旋风燃烧加热炉的主淫

本文论述了我国第一座成功地采用粉煤液排渣式旋风炉作轧钢加热炉燃烧室的实验研究，文中提出了四面技术经济指标进行全面分析，论述了关键问题和技术对策，立式旋风炉的炉型结构热力参数的确定，捕渣率的率的测定，炉衬材料分析及热平衡测定。     

Experimental study of pseudoplastic fluid flows in a square duct of strong curvature

In this paper, laminar and turbulent flows of pseudoplastic fluids (0.1% and 0.2% by weight aqueous solutions of carboxymethylcellulose) in a square duct of strong curvature were measured using an ultrasonic Doppler velocimetry and microphones. Streamwise velocity in cross-sections of the duct and the fluctuating pressure on walls were measured for different flow rates. The velocity contours and their development along the duct were presented and compared with benchmark experiments by Taylor, Whitelaw and Yianneskis (1982) which were for the laminar and turbulent flows of water. The spectra of fluctuating wall pressures were also presented and analyzed. The objective of this paper was to provide a basis for understanding the pseudoplastic fluid flows in curved ducts. The results were also intended for use in the further development of numerical methods and turbulence models for shear-thinning fluids.     

SIMULATION OF SWIRLING TURBULENT FLOWS AND HEAT TRANSFER IN AN ANNULAR DUCT

The article presents a numerical simulation of swirling turbulent flows and heat transfer in an annular duct. The time-averaged governing equations are solved, which are closed by a new algebraic Reynolds stress model (ASM). The simulation is performed under different flow conditions. The calculated results of gas axial and tangential velocities, turbulent kinetic energy, temperature, and local heat transfer coefficients on the inner and outer walls of the annulus are provided. They illustrate the effect of swirl number, inlet axial velocity, and ratio of inner to outer radius on the mean flow and turbulence properties, as well as on enhancing heat transfer in the annular duct.     

Experimental Studies on Swirling Gas—Particle Flows in a Spouting —Cyclone Combustor

The gas and particle time-averaged velocity rand RMS fluctuation velocity of swirling gas-particle flows in a spouting-cyclone combustor were measured by a hot-ball probe and a conventional LDV system. The results show large velocity slip between the two phases both in tangential and axial directions and high nonisotropic turbulence of the two phases were also observed which is favorable to coal combustion. The particle RMS fluctuation velocity is higher than the gas RMS fluctuation velocity only in some regions of the flow field.     

入流条件对同轴射流旋流燃烧室内湍流流动模拟的影响

应用一种新的代数Reynolds应力模型对同轴射流旋流燃烧室内两股射流为同向旋转和反向旋转条件下的湍流旋流流动进行了数值模拟。为得到合理的流场分布结果，研究了入流条件对同轴射流旋流燃烧室内湍流流动模拟结果的影响。计算中对旋流燃烧室进口处两股旋转射流的轴向与切向速度采用了均匀分布和实验测量分布两种方式来给定。将两种进口速度分布条件下得到的燃烧室内气体轴向与切向速度分布计算结果与实验数据进行了比较。     

加湿湍流燃烧火焰稳定的速度场特性分析

1引言目前,湿空气透平循环(HAT循环)等先进热力循环成为人们研究的重点。此类循环在提高效率和减少NOX排放量的同时,燃烧火焰的温度降低了,火焰将愈加不稳定,所以对加湿湍流燃烧火焰稳定的速度场等特性进行研究是非常有必要的。目前燃烧实验研究大多是基于激光诊断测量技术基础     

Vortex Simulation of Axisymmetrical Flows in Cylindrical Geometries．PartII：Application to Pipes Incorporating an Orifice Plate

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格子Boltzmann方法模拟湍流流动

概述了国内外利用分子动力学研究流动的方法，主要介绍一种新的数值计算方法——格子Boltzmann方法。对此法的原理、模拟的模型及其在湍流流动中的应用进行了综述。分析这种方法在模拟湍流时存在的问题。为湍流流动研究指出了一条新的途径——用分子动力学理论研究湍流流动。     

Thermal Taylor dispersion in an insulated circular cylinder—II. Applications

The thermal dispersion theory derived in Part I is here applied to convective heat transfer in an externally insulated tube possessing a finite wall thickness. Expressions are derived for the mean axial thermal propagation velocity and thermal dispersivity of the composite system for both laminar and turbulent flows. For each, the effect of the nonzero wall thickness is such that is always less than the average fluid velocity . In a laminar flow system, can either be larger or smaller than the fluid diffusivity _f, depending upon the thermal properties of the fluid and wall, as well as upon the magnitude of the Peclet number. For turbulent flows, can be either larger or smaller than both _f and the zero wall thickness effective thermal dispersivity, , although now it further depends upon the Prandtl number.     

Modelling of heat transfer and fluid flow for decaying swirl flow in a circular pipe

In the present study, a propeller type swirl generator was developed, and its effects on heat transfer and fluid flow were investigated numerically and experimentally for air flow in a pipe. In the numerical study, for axisymetrically, incompressible turbulent swirl flows, the Navier-Stokes equations were solved using the k-ε turbulent model. So that a computer program in Fortran was constructed using the SIMPLEC Algorithm. In experimental work, axial and tangential velocity distributions behind the swirl generator were measured by using hot-wire anemometry. Experimental and numerical axial and tangential velocity distributions along the pipe were compared, and good agreement was found. Axial velocity profile showed a decrement in the central portion of the pipe and an increased axial velocity was seen in near the wall. Tangential velocity profiles had a maximum value and its location moved in radially with distance. The effects of swirl flow on the heat transfer and pressure drop were also investigated experimentally.     

轴向切向进风强旋气粒流动的PDPA研究

本文用相位多普勒测速仪ＰＤＰＡ研究了轴向和切向同时进气、轴向供粉的旋流数为１．５的突扩强旋气粒湍流两相流动，给出了气相和颗粒相的轴向和切向时均速度场，湍流脉动场、颗粒浓度场、揭示了强旋气粒湍流两相流动的各向异性，并表明两相速度及湍流脉动间关系不同于类似流型的Ｓ＝０．４的弱旋情况。