新型置换通风系统耦合作用机理分析研究

建立了办公室房间侧墙上置风口置换通风方式试验模型,测试了不同负荷情况下房间非等温送风射流的速度分布和温度分布.利用无因次速度变化曲线,分析了送风射流的发展规律,依据送风射流边界层理论,分析了房间内送风射流与周围空气热质交换以及送风射流与热羽流对房间温度分层的影响,阐明了新型置换通风系统耦合作用机理.     

新风送风方式对辐射吊顶制冷量影响研究

为解决辐射吊顶在制冷量和消除湿负荷方面的不足,辐射吊顶加独立新风系统成为了国内外学者们的重点研究对象。通过对贴附射流、置换通风加辐射吊顶系统的比较试验,研究新风的不同送风方式对辐射空调系统制冷能力的影响。结果表明:贴附射流送风方式主要通过增大对流换热量提升辐射空调制冷量,相较于置换通风,其总制冷量有所提高,其中对流换热量提高34.29%,但辐射换热量却有所降低。     

喷丸打磨厂房气流组织模拟

使用PHOENICS软件，采用标准湍流k—ε模型对多种工况下喷丸打磨厂房空间分层气流组织进行三维紊流模拟。分析了高大厂房内的水平隔断气流送风喷口类型、送排风口位置和障碍物高度等因素对隔断气流的影响，为大空间变动尘源复杂气流的优化组织研究提供了参考。     

一回路射流加氢系统实验研究

为了获得影响射流加氢系统性能的因素，本研究在基于1:1原型设计的射流加氢试验回路上开展试验，最终获得了射流加氢系统中喷射泵氢气引射流量、混合管内混合物流速、混合管内混合单元的不同数量和组合方式、气体分离器内气相压力对射流加氢系统加氢效率的影响曲线。结果表明，增加氢气引射流量、混合管内混合物流速或者气体分离器气相压力都会提高系统的加氢效率，混合管内部混合单元的第3种组合方式将具有最好的加氢效率。在主给水流量为45m³/h，混合单元为第3种组合方式的条件下，试验系统出口溶解氢浓度达到了2.7mg/kg，满足了核电站一回路启动时的加氢浓度要求。     

国内复合辐射供冷空调系统研究现状

介绍了辐射供冷的原理及其常用的3种送风方式的优缺点,综述了地板送风与地板辐射供冷空调系统、置换通风与顶板或地板辐射供冷空调系统、贴附射流作用下顶板辐射供冷加置换通风空调系统3种复合辐射供冷空调系统解决结露问题的研究进展,对比分析了采用3种复合辐射供冷空调系统房间内的热舒适性研究成果。结果表明,这3种复合辐射供冷空调系统均能有效减轻结露现象,其中贴附射流作用下顶板辐射供冷加置换通风空调系统防止结露效果最显著。置换通风的特性决定了置换通风与地板辐射供冷空调系统在维持良好的室内空气品质和室内热舒适环境方面优于地板送风与地板辐射供冷空调系统。     

旋转钻头非自由多股淹没射流的计算分析

为了研究非自由淹没多股射流流场的运动规律，了解非自由射流固壁及射流方式对流场结构的影响，利用计算机模拟了三维多股射流的几种情况，通过分析，揭示了流场的结构形成过程与运动规律。     

结构动力学特性分析中连接刚度的有限元建模对比研究

大型复杂结构都是由多个子结构组合而成的，其连接刚度会显著影响整体结构的动力学特性。本文已简单搭接板为例，采用有限元方法建立了连接刚度的体单元、加厚板单元、多点约束单元等有限元分析模型，获得了不同建模方式下，搭接板在外载荷作用下的静力学响应和无阻尼自由振动的动力学特性参数，对比分析了不同建模方式对结构动力学特性的影响。     

清除飞机客舱引气污染物的空调三角波送风方法

针对目前飞机客舱空调采用恒值信号送风对引气污染物排出舱外效果不理想的问题，提出了一种飞机客舱三角波信号送风方式。建立了Boeing 737客舱仿真模型，并验证了客舱模型的可靠性。以NO₂作为引气污染物，模拟了客舱空调采用三角波信号送风和恒值信号送风时不同时刻的湍流强度，使用无量纲标准化污染物浓度来评估不同工况下的排污能力，并结合由吹风感引起的乘客不满意率DR,得出最佳的送风工况。结果表明：三角波信号送风降低了客舱内NO₂质量分数，混合送风方式下排污效率最高。     

混合空气空调送风方式的探讨

对低温蓄冷低滴送水中央空调系统中的送风方式进行了分析与探讨，认为采用回风、新风、露点风混合调节到合适的温、湿度送风的方式比低温送风方式要好。     

体壳单元连接MPC法的计算精度分析

在对体单元和壳单元组合模型进行分析计算时,常使用ANSYS软件中的MPC法,其计算精度比共节点法高,通过研究发现,多点约束(MPC)法的计算精度受连接处体单元和壳单元网格划分方式的影响.利用有限元理论分析其原理,结合算例定性地说明其影响方式,最终给出了连接处体单元和壳单元合理的网格划分方式,提高了计算精度.     

Comparison of volume flow rate and volume-averaged local mean age of air for evaluating ventilation performance in natural ventilation

Evaluating the ventilation performance is an important part of natural ventilation studies. We considered the volume flow rate, which is used by many researchers, and the volume-averaged Local mean age of air (LMA) as the ventilation performance parameters to evaluate the performance of natural ventilation. Computational fluid dynamics (CFD) simulations were performed on an isolated building model of cross ventilation that contained two openings on the windward and leeward wall and single-sided ventilation model that consisted of a single opening. Parametric studies were performed to evaluate the ventilation performance of eight different building configurations in cross ventilation and single-sided ventilation. Using the volume flow rate it was difficult to evaluate the ventilation performance when the inlet and outlet were very close in cross ventilation and, in single-sided ventilation, it was difficult to evaluate when the airflow speed was fast near the opening but did not penetrate inside the building. While the volume-averaged LMA was an adequate parameter for representing the ventilation performance of the building, the LMA field was a more accurate representation of the local ventilation performance inside the building than the velocity vector field.

     

室内污染物扩散的通风优化数值模拟

为了减小房屋装修后室内甲醛对人体的危害,了解不同通风方式及通风速度下室内甲醛浓度的分布特征是关键。本文采用CFD方法,模拟2种基本通风方式室内气流组织的流动形式,研究了不同通风方式、不同送风速度对室内甲醛的浓度分布的影响,数值模拟表明:与异侧送回风通风方式相比,同侧送回风形式更能有效减小室内甲醛的浓度,因而室内通风方式应优先选择同侧送回风。在同侧送回风气流组织形式下,送风速度过小或过大均致使人站或坐高度平面上甲醛浓度增大,因而应根据甲醛的散发强度,选择合适的送风速度,如在本文中送风速度以2m/s左右为宜。优化室内污染物扩散的通风形式,对室内通风设计和气流组织的研究具有一定的指导意义。     

Experimental study of ventilation performance of a novel integral-type air conditioner with heat recovery using R290

The leaking safety of air conditioner using R290 has been a research hotspot in recent years, one method to lower the risk of explosion after leakage is utilizing ventilation. For fresh air conditioner, it's common to use thermal anemometry and differential pressure flowmeters to measure ventilation flow rate. However, there is non-negligible error especially under low air volume flow rate conditions. In this paper, a novel integral-type air conditioner with heat recovery using R290 is proposed. And the relevant influencing parameters are analyzed and experimentally studied. The results show that tracer gas method is an effective way to measure ventilation flow rate, and the novel integral-type air conditioner can meet the needs of the ventilation standards. The air volume flow rates of indoor unit fan and outdoor unit fan are dominant factors affecting ventilation flow rate. The outlet area of exhaust air duct is more sensitive than the inlet area of fresh air duct in exerting influence on ventilation flow rate, while the indoor temperature has a mild impact on ventilation flow rate.     

A computational analysis of the airflow in a twin-track subway tunnel with a sliding-curtain to improve ventilation performance

A computational model of an actual Seoul subway tunnel was analyzed in this study. The computational model was comprised of one natural ventilation shaft, two mechanical ventilation shafts, one mechanical air supply, a twin-track tunnel and a train. The natural ventilation shaft discharges and supplies air due to the train’s movement. The mechanical ventilation shaft and the mechanical air supply discharges and supplies, respectively, the airflow from the axial flow fans in the middle of the ducts of the shafts. A sliding-curtain was installed in the tunnel. The objective of this study was to numerically investigate train-induced airflow in the twin-track subway tunnel with natural and mechanical ventilation shafts and an installed curtain. The numerical analysis characterized the aerodynamic behavior and performance of the ventilation system by solving three-dimensional turbulent Reynolds-averaged Navier-Stokes equations. ANSYS CFX software was used for the computations. The airflow velocity from the computational results was validated by experimental results. Understanding the flow pattern of the train-induced airflow in the tunnel is necessary to improve ventilation performance. The ventilation and aerodynamic characteristics in the tunnel, including train-induced airflow, were investigated by analyzing the volume flowrate at the exits of the ventilation shafts and the velocity in the tunnel. The computational results were compared to cases with and without a curtain installed in the twin-track tunnel. As the train passed the mechanical ventilation shafts, the quantity of discharged-air in the ventilation shafts decreased rapidly. The flowrate at the exits of the ventilation shafts was gradually recovered with time, after the train passed the ventilation shafts. The airflow at the natural shaft and mechanical ventilation shaft 2, which was closest to the curtain, was increased. The computational results showed that the installed curtain can improve ventilation performance in the tunnel.     

竖井型城市隧道阻滞交通状况下自然通风模型试验研究

以连续竖井的静压分布特性为基础,采用分段模型试验的方法,分4段搭建了南京市中山东路隧道模型,进行阻滞状况下的交通风压通风试验,得到了隧道的自然通风特性,以及竖井通风的一些规律。通过建立通风量与有害气体浓度之间关系的数学模型,研究评价隧道自然通风效果的方法,由此对中山东路隧道通风效果做出评价,得出竖井型城市隧道自然通风的相关结论。     

Estimation of appropriate capacity of ventilation system based on the air infiltration rate in Korean classrooms

The appropriate capacity of a ventilation system based on the air infiltration rate in Korean classrooms is investigated to obtain optimal design conditions for ventilation systems. Theoretical and the experimental analyses are performed to estimate the proper ventilation capacity with a consideration of the air infiltration, the indoor air quality, and the ventilation rate. The air infiltration rate of the classroom is measured within the range of 0.5–1.5 1/h, and the required ventilation rate should be decided not by the contaminants (Formaldehyde and TVOC) emitted from the construction materials but by the carbon dioxide (CO₂) emitted from human breath. The appropriate capacity of the ventilation system based on the air infiltration rate of the classroom for elementary schools is 500CMH and for middle and high schools is 800 CMH. The measured and the estimated values of CO₂ concentrations are very similar and the modeling equation of CO₂ concentration can be used as a reference for the proper estimation of ventilation rate in Korean schools.     

3种置换通风方式下舱室内流场数值分析

针对置换通风方式下舱室内流场分布情况,采用RNG k-ε涡粘性湍流数学模型,建立了常用的3种不同置换通风方式下的舱室分析模型,对舱室内速度场、温度场及污染物浓度分布情况进行了数值分析。根据《乘用车内空气质量评价指南GB/T 27630—2011》中的评价方法,对3种通风方式进行了对比分析。结果表明:前进后出置换通风方式能够有效降低舱室内工作区域CO2浓度,温度调节能力强,且温度变化梯度小,可使舱室内工作区域得到品质较高的空气分布、较好的热舒适度和较高的通风效率。该种置换通风方式可用于舱室内空调通风系统的设计。     

Parametric study on a forward-curved blades centrifugal fan with an impeller separated by an annular plate

A parametric study on the geometry of an impeller in a forward-curved blades centrifugal fan for residential ventilation has been carried out in this work. Numerical analysis of a forward-curved blades centrifugal fan was carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. A validation of numerical results was conducted by comparison with experimental data for the pressure and efficiency. The impeller separated by an annular plate was employed, and the annular plate height and the angle between the upper and lower impellers were selected as the geometric parameters to investigate their effects on the efficiency of the forward-curved blades centrifugal fan. Additionally, the impeller geometry having the highest efficiency was tested with the number and exit angle of blades. The results show that the impeller with properly installed annular plate improves the aerodynamic performance of the forward-curved blades centrifugal fan.     

不同通风方式下热喷涂车间内粉尘运动规律的实验研究

为获取热喷涂工艺过程中微纳米粉尘颗粒的控制措施,根据相似原理,以热喷涂车间为原型,结合气固两相流理论,建立了热喷涂车间相似实验模型,对不同通风除尘条件下热喷涂车间内微纳米粉尘颗粒的运动与扩散规律进行实验研究。研究结果表明：机械通风对降低热喷涂车间微纳米粉尘颗粒浓度具有明显效果;单位时间内通风流量越大,车间呼吸层微纳米粉尘颗粒浓度越低,清除时间越短;通风速率相同的条件下,采用车间底部和侧面组合的通风方式较仅采用侧面强力通风,更利于呼吸层微纳米粉尘颗粒的排除和沉降。     

中型高压电机轴径向混合通风结构的强化散热特性模拟

为了提升电机的通风冷却性能、降低其运行温升,以一台400 kW中型高压电机为例,采用轴径向混合通风结构,通过磁-流-固耦合模拟研究整体电机稳态条件下温升影响规律,提出温升均匀性系数对两种通风结构的冷却效果进行量化评价。研究结果表明：相对于轴向通风结构,混合通风结构温升分布更加均匀,在电机内层和外层绕组温升均匀性系数分别提高了85.78%和6.23%;进一步探讨了径向风道高度及数量对电机温升的影响,径向风道高度为6 mm、径向风道数量为13个时冷却效果最好。