爆破位置对深凹露天矿山炮烟扩散的影响研究

深凹露天矿山由于其特殊的结构,爆破产生的炮烟扩散稀释较为困难,严重危害生产作业人员的生命安全与健康。基于实际矿山构建了深凹露天矿山的二维物理及数学模型,采用非稳态数值分析方法研究了不同爆破位置下,深凹露天矿山采坑内爆破炮烟的扩散规律。研究结果表明：不同爆破位置下,露天采坑内均出现复环流,爆破点位置是影响露天采坑内风流结构特征的重要因素；露天采坑内的炮烟最高浓度均随着时间变化而逐渐下降,但下降的速率逐步减小,呈现三个阶段的下降趋势；爆破位置位于背风侧时露天采坑内的炮烟最高浓度和降至安全浓度所需时间远高于迎风侧三个爆破位置；随着背风侧爆破点距采坑底部距离的减小,炮烟最高浓度及降至安全浓度所需时间先降低后增加,炮烟最高浓度及降至安全浓度所需时间随着迎风侧爆破位置距采坑底部距离的减小而增加。研究结果对于指导深凹露天矿山企业合理组织爆破后的生产作业和保障作业人员安全具有重要意义。     

Experimental investigation of far-field human cough airflows from healthy and influenza-infected subjects

Seasonal influenza epidemics have been responsible for causing increased economic expenditures and many deaths worldwide. Evidence exists to support the claim that the virus can be spread through the air, but the relative significance of airborne transmission has not been well defined. Particle image velocimetry (PIV) and hot-wire anemometry (HWA) measurements were conducted at 1 m away from the mouth of human subjects to develop a model for cough flow behavior at greater distances from the mouth than were studied previously. Biological aerosol sampling was conducted to assess the risk of exposure to airborne viruses. Throughout the investigation, 77 experiments were conducted from 58 different subjects. From these subjects, 21 presented with influenza-like illness. Of these, 12 subjects had laboratory-confirmed respiratory infections. A model was developed for the cough centerline velocity magnitude time history. The experimental results were also used to validate computational fluid dynamics (CFD) models. The peak velocity observed at the cough jet center, averaged across all trials, was 1.2 m/s, and an average jet spread angle of θ = 24° was measured, similar to that of a steady free jet. No differences were observed in the velocity or turbulence characteristics between coughs from sick, convalescent, or healthy participants.     

辛置煤矿10#煤综采工作面防灭火技术研究与应用

针对辛置煤矿10#煤综采工作面煤层自然发火的特点,采用现场实测分析及注胶防灭火的方法,对工作面煤体漏风情况、回采巷道内风流温度、CO及CH4浓度进行了监测,并应用了注胶防灭火的技术。针对工作面煤体内多处漏风严重,应用粉煤灰、高分子胶体注胶技术进行防治后,各监测点风流温度及煤层温度均得到有效降低,保证了工作面安全推进。     

Fire detection in computer facilities

A recent fire in a computer center in Canberra, Australia, prompted an investigation of the installed smoke detection system. The opportunity was also taken to evaluate alternate detection equipment in the actual center under operational conditions. One device tested was VESDA, a new highly sensitive smoke detector developed in Australia for clean occupancies such as computer rooms and telephone exchanges. Details of the test program and the effects of high room airflows on all forms of detectors are presented. The effectiveness of VESDA in giving very early warning of fire is demonstrated. Reference: Peter F. Johnson, Fire Detection in Computer Facilities,Fire Technology, Vol. 22, No. 1, February 1986, p. 14. Note: This paper is a modified version of a CIRL Major Report No. 251, 1984, prepared for Department of Housing and Construction, Canberra, Australia.     

某HERMES专营店空调设计研究

本文介绍了某HERMES专营店的空调设计方法。为了使室内获得舒适的温度以及合理的气流组织形式,笔者建立了专营店空调设计的物理几何模型,利用CFD软件对该有限空间的气流场和温度场进行了仿真模拟,并根据仿真结果修正了原有的空调设计方案。专营店的空调正常运行后,笔者又对其运行状况进行了现场测量,并将测量记录的结果与CFD仿真模拟结果进行对比分析,符合性较好。本文的研究可以作为利用CFD软件评估和指导有限空间空调设计的有益尝试。     

A study of the dispersion of expiratory aerosols in unidirectional downward and ceiling-return type airflows using a multiphase approach

Dispersion characteristics of expiratory aerosols were investigated in an enclosure with two different idealized airflow patterns: the ceiling-return and the unidirectional downward. A multiphase numerical model, which was able to capture the polydispersity and evaporation features of the aerosols, was adopted. Experiments employing optical techniques were conducted in a chamber with downward airflow pattern to measure the dispersion of aerosols. Some of the numerical results were compared with the chamber measurement results. Reasonable agreement was found. Small aerosols (initial size airflow stream was the major dispersion mechanism of expiratory aerosols in ventilated indoor environments. Dispersion by turbulence was about an order of magnitude less than that by bulk flow transport but considerable distance could be achieved by turbulent dispersion with long enough settling time. It was demonstrated that the dispersion of expiratory aerosol could be controlled by manipulating the ventilation airflow patterns in indoor environments.     

套室内人体热舒适的研究

借助于通用流场计算软件PHOENICS，在考虑了外界气温、太阳的热辐射条件，家具以及人员等室内微气候影响的情况下，预测了两室一厅套室内气流三维流场和温度场。得到了套室内气流的速度、温度和人体热舒适指数等参数的分布，并经过评定，该套室内的热环境达到了人体的舒适性要求。模拟计算结果对套室的设计及其空调系统的配置具有重要的参考价值，并为套室内人体热舒适的进一步研究和室内空气品质问题的研究奠定了基础。     

排风隔热窗一维简化传热模型研究

排风隔热窗作为一种新型外窗结构,可以有效地降低室内侧玻璃表面与室内空气之间的温差,减少外窗形成的室内负荷,改善室内的热舒适性。利用能量守恒原理,建立了排风隔热窗的一维简化传热数学模型,研究了该结构外窗在夏热冬冷气候条件下的传热特性。将排风隔热窗的简化传热数学模型和区域模型的计算结果进行比较,计算结果表明,简化模型可以较好地模拟排风隔热窗的传热特性,适用于研究初期的简化计算和工程计算。     

飞机喷漆机库风平衡调试施工技术

如今国内航空产业飞速发展,适用于不同飞机机型的喷漆机库将会逐步建造。喷漆阶段对喷漆大厅内的气体流态要求非常高,要求气流在落差较高空间内均匀且稳定地送至飞机舷窗部位并被下方的排风口排出,同时保持总送排风风量,使喷漆大厅具备微负压。结合常规风平衡调试方法和美国波音公司喷漆机库风平衡调试方法以及飞机喷涂技术要求,经过多次试验并分析,总结介绍了系统性的风平衡调试方案,为后续类似喷漆机库的风平衡调试工作积累了经验。     

Thermal characteristics of an air-cooled open-cathode proton exchange membrane fuel cell stack via numerical investigation

In light of stricter emissions regulations and depleting fossil fuel reserves, fuel cell vehicles (FCVs) are one of the leading alternatives for powering future vehicles. An open-cathode, air-cooled proton exchange membrane fuel cell (PEMFC) stack provides a relatively simple electric generation system for a vehicle in terms of system complexity and number of components. The temperature within a PEMFC stack is critical to its level of performance and the electrochemical efficiency. Previously created computational models to study and predict the stack temperature have been limited in their scale and the inaccurate assumption that temperature is uniform throughout. The present work details the creation of a numerical model to study the temperature distribution of an 80-cell Ballard 1020ACS stack by simulating the cooling airflow across the stack. Using computational fluid dynamics, a steady-state airflow simulation was performed using experimental data to form boundary conditions where possible. Additionally, a parametric study was performed to investigate the effect of the distance between the stack and cooling fan on stack performance. Model validation was performed against published results. The temperature distribution across the stack was identical for the central 70% of the cells, with eccentric temperatures observed at the stack extremities, while the difference between coolant and bipolar plate temperatures was approximately 10°C at the cooling channel outlets. The results of the parametric study showed that the fan-stack distance has a negligible effect on stack performance. The assumptions regarding stack temperature uniformity and measurement were challenged. Lastly, the hypothesis regarding the negligible effect of fan-stack distance on stack performance was confirmed.