循环湍动流化床的研究进展

循环湍动流化床是将循环流化床和湍动流化床的优点综合为一体的新型流化床反应器,使床层在操作过程中不仅能在较高的颗粒循环速率下操作,处理能力大,且床层混合充分,气固之间传质传热性能好。对循环流化床、湍动流化床和循环湍动流化床三种装置图进行了简单的对比,并介绍了近年来一些学者在该领域的研究现状和进展,探讨了操作条件对循环湍动流化床反应器内流动特性的影响规律,并指出了今后循环湍动流化床研究的方向,为加快循环湍动流化床的工业应用提供参考。     

基于流态化技术的振动流化床气固两相流动分析

在对基于流态化技术的振动流化床气固两相流动的欧拉（Euler）方法的双流体模型研究的基础上,利用专业流体力学分析软件Fluent对褐煤颗粒床层进行数值模拟．研究振动、风速、褐煤颗粒粒度等参数对振动流化床床层中褐煤颗粒均匀流化的影响．实验结果表明：振动及气流的交互作用,可有效抑制褐煤颗粒在床层中的返混现象,使得振动流化床褐煤颗粒干燥均匀;选择双流体模型,将Fluent用于振动流化床气固两相流动数值模拟,是一种行之有效的数值模拟方法．     

基于信息融合技术的气固流化床流型辨识

基于多传感器信息融合技术,提出了一种新的气固流化床流型判别的方法.利用差压传感器和电容层析成像传感器分别采集压力和空隙率信号,提取特征值并进行各自的判别.对两个传感器的判别结果采用D-S证据理论进行决策级目标识别数据融合,得到最终的流态判别的结果.实验结果表明所提出的新方法是有效的,提高了流型判别的准确性.     

复杂性理论在气固流体床流型识别中的运用

提取复杂性理论中的涨落复杂性Cf及算法复杂性C(n)参数对气固流化床压力脉动信号随流化床操作气速增大历经不同流型的变化趋势进行分析.研究结果表明,在起始流化至鼓泡态转变的过程中,气-固体系会进行一种所谓的"重构"现象,复杂性参数能明确地指示固定床、鼓泡流化及湍动流化等不同流型之间的转变过程,为流型识别提供了新思路.     

气液两相流泵的研究进展

介绍了气液两相流动的主要计算模型,总结了现有两相流泵的特点,对有关两相流泵的流场分析,性能预测,试验研究及水力设计等方面的现有成果分别进行了综述,对应进一步深入研究的问题及研究中应遵循的一些原则进行了初步探讨。     

循环湍动流化床实验平台设计及实验研究

为克服传统循环流化床和湍动流化床固含率低和气固反混严重等缺点,设计出一种新型流化床——循环湍动流化床,并在该装置上进行了压力分布及变化规律的实验研究。结果表明:不同静床高度,相同的床层截面上,压力梯度仅有微小的变化,说明床层内气固接触均匀;压力梯度波动标准偏差的变化规律表明静床高度越大,转折点对应的气速会相应地增大,然后减小,转折点对应的气速是形成循环湍动流态化的初始转变速度。     

固气两相流理论在路面铣刨碎料清理设备中的应用

研究固气两相流技术在沥青路面铣刨工作面清理设备中应用的可行性。针对冷铣刨机工作面遗留的铣刨废料进行了固气两相流分析,确定了清理设备的主要性能和结构参数的计算方法,通过试算证明了这种应用的可行性。     

基于ARMA模型的气固流化床过程监控

基于ARMA模型，提出了一种新的气固流化床流态化过程监控方案。利用Honeywell公司生产的24PC系列压力／差压传感器获取气固流化床压力波动信号，拟合n阶自回归m阶滑动平均模型ARMA(n，m)。通过分析，确定自回归阶数n的阈值，实现流态化过程监控。监控在实验室的气固流化床实验装置上进行，初步实验表明，方案用于气固流化床流态化过程监控是有效的。     

气固流化床流化本质的非线性特征提取

引入互信息和非线性动力学理论对气固流化床的压力脉动和颗粒浓度信号进行研究,从互信息的角度提取传统单一参数检测所不能提取的信息,同时用复杂性算法分析采集的时间序列信号,从一个新的角度揭示了流化床系统的非线性本质.     

Advances in research on a multi-channel on-line ferrograph

This paper introduces the basic principle, functions and test results of a multi-channel on-line ferrograph. The instrument catches wear debris with an electromagnet, detects wear debris with a photoelectric sensor, and controls sampling and data processing with an 8098 single-chip microprocessor which can communicate with a master computer. The instrument has four sampling channels, which can monitor not only one machine but also four machines one by one. The software of the instrument includes five modules which are a main program, a keyboard control program, a floating point operation program, a serial communication program and a self-checking program. The results of experiments on a gear box show that increasing average values detected by the instrument correspond to increasing load, so the instrument can meet the need for on-line monitoring of the wear condition of machines.     

PC-based gas-solids two-phase mass flowmeter for pneumatically conveying systems

The development and performance of a PC-based instrumentation system for measuring the mass flow rate of gas-solid flow in a pneumatically conveying system have been discussed in this paper. A laboratory scale pneumatic conveyor incorporating facilities for calibration has been fabricated for this purpose. The test section is a vertical plexiglass tube of diameter 12.7 mm with an upward flow direction and sand has been used as the solid phase. The principle of measurement is based on inferential technique. Instantaneous velocity and concentration of the bulk solids are measured using a pair of electrodynamic sensors and a capacitance sensor, respectively. Several modifications of the existing technique of measurement have been suggested.     

磨削颤振特性研究进展

首先阐述了磨削加工过程中的颤振会导致工件尺寸误差、形位误差、表面粗糙度和波纹度等指标的恶化,直接影响了工件加工精度和表面质量;接下来系统地介绍了现有的、比较有代表性的磨削颤振机理研究技术;最后对磨削颤振特性研究技术的发展前景进行了展望,指出了该研究领域当前需要进一步研究的问题和发展趋势,为今后的研究提供参考。     

化学修饰型复合汞膜电极的研究进展

简单介绍了常规玻碳汞膜电极的优点及存在的问题,重点评述了化学修饰型复合汞膜电极产生的必然性、类型、制备及应用,并对其发展趋势作了展望。共引用文献42篇。     

SK型静态混合器内的流动特性数值研究

基于微尺度流动特征的角度,研究SK型静态混合器内部湍流时的流动规律.利用计算流体力学专业软件并采用雷诺时均方程和标准的k-ε湍流模型对SK静态混合器内的湍流状态下的三维不可压缩流场进行数值模拟.数值计算和研究表明在含有多个SK型螺旋元件的静态混合器内,受元件衔接处的切割作用的流体将在其后的混合元件的3L/8处完成重新汇合;研究了SK型静态混合器的主要参数对流动阻力的影响,从而为静态混合器的优化设计提供了依据.     

纳米金刚石薄膜制备技术的研究进展

介绍纳米金刚石薄膜的特性和应用,综合叙述以化学气相沉积技术为基础、拓展多种纳米金刚石薄膜制备技术的研究进展,分析纳米金刚石薄膜的特性机理,并展望今后的研究方向.     

Large eddy simulation of turbulent premixed flame in turbulent channel flow

Large eddy simulation of turbulent premixed flame in turbulent channel flow is studied by usingG-equation. A flamelet model for the premixed flame is combined with a dynamic subgrid combustion model for the filtered propagation flame speed. The objective of this work is to investigate the validity of the dynamic subgridG-equation model to a complex turbulent premixed flame. The effect of model parameters of the dynamic subgridG-equation on the turbulent flame speed is investigated. In order to consider quenching of laminar flames on the wall, wall-quenching damping function is employed in this calculation. In the present study, a constant density turbulent channel flow is used. The calculation results are evaluated by comparing with the DNS results of Bruneaux et al.     

Designing for turbulent lubrication

There are three turbulent lubrication theories which lend themselves to convenient numerical solution of the governing Reynolds' equation. Two of the theories have been subjected to critical analysis in the literature, whilst the third due to Hirs is more recent. The theory of Hirs is considered from the standpoint of the designer. The predictions of the theory for the performance of a plane inclined surface thrust bearing are delineated and compared with previous results utilizing the alternative approaches. Thoughts on the adequacy of the existing approaches to turbulent lubrication are presented and future possibilities considered.     

Effects of turbulent mixing on spray ignition in spray system

When a column of droplets freely falling from an ultrasonic atomizer was ignited behind a reflected shock, no ignition occurred at a temperature below 1100 K, even if the pressure was as high as IMPa. Although, a higher temperature condition ensured ignition, no luminous flame was observable by high-speed photography, and even if a luminous flame lump appeared at an extremely high temperature, it disappeared without spreading over the entire column of droplets in this case. It is known however that, if a fuel is injected into a diesel cylinder or an electric furnace, ignition occurs even at a temperature as low as 650 K with a luminous flame spreading over the entire spray. These differences could be caused by the effects of turbulent mixing between fuel droplets and hot air, in fact, turbulence-generating rods were placed on the upstream side of the spray column. Experimental results indicates that the ignition limit was lowered to 840 K, and the ignition delay period was decreased by increasing the intensity of turbulence. Furthermore, the light emission of the flame was intensified, and normal spray combustion was maintained in the low-temperature atmosphere after the shock tube ceased its operation.