Experimental investigation on the plasma morphology of ablative pulsed plasma thruster with tongue-shaped and flared electrodes

Ablative pulsed plasma thrusters(APPTs) are considered as an attractive propulsion option for station-keeping and drag makeup purposes for mass-and power-limited satellites. In order to understand the physical mechanism of APPTs, high-speed camera and optical emission spectroscopy are utilized to investigate the plasma characteristics including the spatial distribution and composition between the electrodes. The plume images and spectra at different times and positions are experimentally recorded, and the spatial distribution, composition, and trajectory of plasmas can be concluded through analyzing them. With the increase of the distance from the ablation surface, two clusters of plasmas near the anode and cathode meet downstream,and the species and density of plasmas tend to be uniform.     

融合环境因素的有限空间毒气扩散危害程度分析

为探究环境因素对毒气扩散危害程度的影响,通过对比有限空间内外环境差异,了解气体在有限空间内受力情况,并以传统高斯烟羽模型为基础,考虑扩散气体与有限空间边界碰撞产生的反射作用,建立了适用于有限空间气体扩散的改进高斯烟羽模型。深度剖析有限空间气体扩散环境,挖掘气体扩散主要关联因子,构建风速、地表粗糙度对有限空间气体扩散的影响函数;参照有限空间环境特征,分别设置3种不同风速与2种不同地表粗糙度,推求6种不同环境条件下气体扩散面积,阐明风速与地表粗糙度对有限空间气体扩散的影响程度。结果表明:在单一风速条件下,风速越高,地表粗糙度越低,洞室内H2S气体滞留时间越短,洞室内气体的扩散面积越小;风速越低,地表粗糙度越高,洞室内气体的扩散面积越大。     

催化裂化烟气湿法脱硫除尘装置运行情况分析

主要介绍了催化裂化烟气净化（湿法脱硫除尘）项目在中海油惠州石化有限公司1.2 Mt/a催化裂化装置上的运行情况。项目运行效果达到设计指标要求，主要包括污染物排放、能耗和连续排放监测系统指标等。但运行过程中出现外排水悬浮物浓度波动和烟气蓝烟拖尾现象，经过原因分析，通过流程优化、三剂使用和操作调整解决了问题，保证了项目的平稳运行。     

基于决策树的羽流追踪机器人自主决策方法研究

针对无法获得可靠羽流流向信息不利于实现羽流追踪的问题，提出了一种基于决策树的羽流追踪移动机器人自主决策方法。该方法通过移动机器人两侧的浓度传感器采集到的浓度信息，利用追踪的行为规则建立决策树模型，获得行为决策信息，使机器人高效地追踪到羽流并精确地定位。由于浓度变化关系蕴含了羽流的流向及流速信息，从而取代了传统方法中流向及流速传感器。在扩散环境下，通过移动机器人羽流追踪实验，实现了良好的源定位效果。     

激光扫描焊接熔池及等离子体动态行为

以5A06铝合金为试验材料，采用高速摄影技术对激光扫描焊接过程中的熔池及等离子体羽辉动态行为进行拍摄，对比分析了常规单激光焊接与激光扫描焊接条件下的熔池表面流动特征和等离子体羽辉波动特征. 结果表明，一定条件下的摆动激光光束相比于单激光光束，能够极大地增强等离子体羽辉的稳定性，延长其存在周期，同时熔池流动的方向性增强，稳定性提高，整个焊接液态熔池表面不存在“回流”现象，熔池流动产生的流体动压力对匙孔的冲击力作用降低，匙孔的稳定性提高.     

平巷烟流滚退火烟羽流模型及其特征参数研究

为研究矿井火灾时期发生烟流滚退时火源区域烟流流动规律,分析了矿井水平巷道火烟浮羽流及顶板射流的成因和特点,并运用环境流体力学及传热学的相关理论,分析了水平巷道火灾烟流滚退规律,结合积分法建立了火烟浮羽流和顶板射流的数学物理模型。通过对滚退烟流与巷壁之间的热交换过程的分析,推导出滚退发生时烟流逆行距离的函数表达式,联合火烟浮羽流和顶板射流数学物理模型,得出求解烟流滚退逆行距离的数学方程式。     

The Balcony Spill Plume: Entrainment of Air into a Flow from a Compartment Opening to a Higher Projecting Balcony

In the design of smoke ventilation systems, a crucial input parameter for balcony spill plume calculations is the mass flow rate of gases at the spill edge. In some cases, depending upon the specific geometry, these calculations can require the entrainment of air into a flow from a compartment opening to a higher projecting balcony to be determined. Entrainment of air into these smoke flows are not well understood and the current guidance available to the designers of smoke ventilation systems is crude. This work presents a simple empirical correlation to predict the entrainment of air into these flows, and hence, the subsequent mass flow rate of gases at the spill edge. A combination of computational fluid dynamics modelling and physical scale modelling was used in the analysis. In general, this work has demonstrated that the current guidance on the entrainment of air into these flows is conservative.     

Experimental measurements,integral modeling and smoke detection of early fire in thermally stratified environments

Building fires go through a series of stages. They start with a fire plume period during which buoyant fire smoke rises to the ceiling. A second stage is the following enclosure smoke-filling period. In this paper, the first stage is the subject, especially for the fire plume behavior in thermally stratified environments in large volume spaces. In NFPA 92B, Morton's integral equation was introduced for calculating the maximum plume rise, and beam smoke detectors were recommended for smoke detection design. In this work, experiments and CFD simulations were conducted in a small-scale enclosure and a large space to investigate early fire movements in temperature-stratified ambients. The results show that in a thermally stratified environment, the axial temperature and velocity of a fire plume decrease more quickly along the vertical axis than in uniform environment, and in some cases the fire plume ceases to rise. The previous integral equation was shown to underestimate the actual maximum height of a fire smoke plume, and also was unable to explain the differences of the maximum heights of low-density and high-density smoke plumes with the same stratification and outlet conditions. The integral equation was improved by introducing two correction factors, and extended for non-linear temperature stratified environments. A light section smoke detection method with three space-protected area was suggested and discussed.     

典型燃煤电厂浆液冷却烟气消白设施SO3治理效果测试研究

分别采用控制冷凝法和异丙醇吸收法对某1 000 MW燃煤发电机组浆液冷却烟气消白设施的烟气SO₃控制效果开展测试。结果表明,机组烟气湿法脱硫设施对SO₃去除效率为62.50%（控制冷凝法）和64.63%（异丙醇吸收法）。烟气经现有超低排放设施协同治理后SO₃质量浓度低于3 mg/m³。浆液冷却设施对SO₃的去除效率仅为6.68%（控制冷凝法）和5.55%（异丙醇吸收法）,烟气SO₃控制效果和环境效益相对较低。建议基于科学论证审慎实施燃煤电厂烟气消白工作,应进一步开展高效SO₃治理技术、测试标准和环境管理政策研究。     

湿烟羽消除中过热度的影响因素分析

消除湿烟羽已成为当前重大环保需求。对消除湿烟羽技术中的关键参数,如烟气加热温度（过热度）与环境温度、环境相对湿度、气压以及烟气温度之间的耦合关系,进行定量、全面分析。研究结果表明：过热度随环境温度升高、气压降低呈指数降低,而随环境相对湿度升高、烟气温度升高呈指数增加;环境温度10 ℃以上时,过热度受环境相对湿度影响的敏感性略强于受环境温度影响的敏感性;气压变化可引起过热度的显著波动,因此对于不同项目,设计时应充分考虑地域性的气压差异;烟气温度变化同样可导致过热度的显著波动,证明消除湿烟羽时应严格控制烟气温度,以便充分利用冷凝再热法的技术优势。