旋风分离器进口回转通道气尘分离模型

针对短路流携尘降低除尘效率的问题,在进口结构采用了回转通道,以此降低进入旋风器空间的向心浓度梯度．对等截面和变截面两种通道形式的分离模型进行了分析,给出了分级效率计算公式及算例     

自然通风冷却塔进风口流场模型的建立及计算

冷却塔的运行状况对电厂的经济性和安全性有较大影响.环境侧风严重影响冷却塔的冷却性能.以逆流湿式自然通风冷却塔为研究对象,建立了冷却塔进风口附近空气流动的数学模型和冷却塔内传热传质的物理模型.采用有限体积法进行了数值计算.得到了冷却塔进风口附近空气动力场的分布规律,同时进行了实型塔的现场测量,与模拟结果对比.该方法可定量评价冷却塔的运行状况,为冷却塔通风量和进风阻力的计算,以及冷却塔全面优化设计和改善冷却塔的冷却性能提供了理论依据.     

On‐line biodegradation monitoring of nitrogen‐containing compounds by membrane inlet mass spectrometry

Membrane inlet mass spectrometry (MIMS) has been developed for the on‐line monitoring of compounds in a continuous stirred tank bioreactor (CSTB) used to simulate a wastewater treatment plant (WWTP). A mixture of four industrially relevant nitrogen‐containing volatile and semi‐volatile compounds was fed to a 3 dm³ CSTB with a hydraulic retention time (HRT) of 24 h. In‐membrane preconcentration/thermal desorption was used for the on‐line monitoring of semi‐volatile compounds (n‐methylpyrrolidinone and tetramethylethylenediamine), while volatile organic compounds (3‐bromopyridine and 2‐chloro‐5‐trifluoromethylaniline) were determined by continuous infusion through the membrane. Quantification of the four compounds was achieved by MS. The CSTB was run for 160 h and, after reaching steady state, n‐methylpyrrolidinone showed removal to levels below the limit of detection, while there was partial biodegradation of 2‐chloro‐5‐trifluoromethylaniline and 3‐bromopyridine. There was no evidence of significant biodegradation for tetramethylethylenediamine. Intermediates in the metabolite pathways of 2‐chloro‐5‐trifluoromethylaniline and 3‐bromopyridine were identified by MIMS, gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). COD was measured off line, and results agreed well with MIMS, although COD data did not provide information on the removal of the individual compounds. Copyright © 2003 Society of Chemical Industry     

10000t/d水泥生产线高浓度、高负压窑尾收尘系统的设计

10 000t/d水泥生产线窑尾采用先进的窑尾 立磨除尘工艺,使窑尾收尘具有高效耐高压等特点;设计中着重解决气流均布、粒子荷电、气流旁路、锁风及壳体耐压等难题。     

一种泄流式进气道堵盖方案技术研究

针对一种适用于整体式固体火箭冲压发动机的泄流式进气道堵盖方案,作了详细方案设计,对工作原理和设计要点作了阐述。采用简化模型,考虑进气道堵盖泄流板前气流参数、泄流板长度及其抬升高度等关键参数,进行了流场数值仿真,得到了泄流板在不同工作状态下的载荷分布情况,仿真结果表明该堵盖具备实现自动开启的可行性,且表明在助推阶段该方案与不安装进气道堵盖方案相比可有效减阻50%。最后,开展了泄流式堵盖方案地面吹试实验,作动装置启动后,进气道堵盖在气流作用下顺利开启,进一步验证了该方案的有效性和可行性。     

PG9351FA型燃气轮机进口可转导叶的控制

为使燃气轮机在启动时防止喘振和在联合循环运行时提高机组整体效率,在燃气轮机的压气机中设置了进口可转导叶(IGV);介绍了PG9351FA型燃气轮机IGV的工作原理,论述设置IGV的作用I、GV的控制过程及故障诊断,揭示IGV在机组不同运行工况中的运行规律,以便于分析IGV的运行状况,提高机组运行的安全性及经济性。     

操作参数对液-液旋流器内部流场及分离性能的影响分析

为了进一步研究液-液旋流器操作参数对其内部流场及分离性能的影响,用FLUENT流体分析软件,采用雷洛应力模型(RSM),对不同的进口流量及底流口压力分别进行了仿真研究,得到不同操作参数下的内部流场情况,并据此分析其对液-液旋流器内部流场及分离性能的影响。     

Simulation of CI engine flow processes for prediction of performance and emissions with different fuels

Diesel-fuelled direct injection compression ignition engines yield high fuel conversion efficiency due to the use of high compression ratios and thus find their place in varied applications. However, tail pipe emissions of conventional diesel engines are a major source of high levels of oxides of nitrogen (NO_x) and particulate matter. Owing to stringent emission legislation, manufactures and researchers are facing tough competition to make them eco-friendly. The present paper deals with a simulation of extensive numerical experiments carried out on a single-cylinder diesel engine by varying timing of inlet valve closing (25°–55°ABDC) and fuels; rapeseed methyl esters and diesel fuel. For this purpose, a zero-dimensional thermodynamics-based model in C⁺⁺ was developed. The model takes into account the engine speed, fuel injection timing and equivalence ratio, temperature-dependent specific heat ratio and inlet valve close timing. The engine performance is evaluated in terms of thermal efficiency, in-cylinder pressure, heat release rate, and NO and soot emissions. It is observed that a significantly delayed closing of the inlet valve would result in loss of charge, and rapeseed methyl ester could be an attractive and viable alternative to petro-diesel fuel.     

侧向支柱对高速旋转冲压增程弹用进气道影响的数值模拟

采用块结构网格与二阶精度流场分区求解技术,对高速旋转含侧向支柱双锥外压轴对称冲压增程弹丸进气道内外复杂流场进行了数值模拟。通过数值模拟得到了对应于不同旋转角速度、不同侧向支柱形状以及不同来流攻角情况下,临界工况时超声速进气道内外粘性流场复杂的波系结构。当高速旋转进气道扩压段有侧向支柱存在时,进气道总压恢复系数和动能系数均有所降低,而流场畸变指数则增大明显。随着转速和攻角的增大,进气道综合性能均有所降低。数值结果显示,采用菱形截面的侧向支柱形状的进气道性能最优。     

进气道结构对含硼固冲发动机二次燃烧性能影响分析

采用标准k-ε湍流模型,单步涡团耗散燃烧模型以及高速气流作用下KING硼粒子点火燃烧模型,开展了不同进气道结构下冲压发动机补燃室内含硼颗粒三维两相燃烧流动数值模拟;分析了在6种进气道结构对硼颗粒点火燃烧以及燃气燃烧效率的影响;研究结果表明：在相同的边界条件下,进气道结构形式对硼颗粒点火影响不大;燃气燃烧效率在双侧180°的进气结构下最高,双下侧90°进气结构的燃气燃烧效率最低;硼颗粒燃烧效率在双侧180°时燃烧效率最高,在中心进气结构下硼燃烧效率最低;补燃室内总燃烧效率在双侧180°进气道结构时最高,在中心进气结构下最低。