基于传质法的吹吸式通风系统流场特性研究

发布时间：2018-01-17 15:13

本文关键词：基于传质法的吹吸式通风系统流场特性研究　出处：《西安建筑科技大学》2014年博士论文　论文类型：学位论文

【摘要】：随着经济的快速发展,工业建筑室内污染控制问题日益突出,高效能的通风技术是实现节能减排、改善工人操作环境与减少大气污染的重要途径。吹吸式通风系统是一种有效的通风方式。由于污染源种类众多、污染源性质各异,吹吸式通风系统设计时并不针对某种具体污染物,而是假定污染物由射流控制和输运,认为控制了气流即控制了污染物,因此吹吸式通风系统的基本性能是指对流场的控制性能,改善基本性能是通过改变吹吸流场特性来完善的。射流特性对吹吸流场特性影响重大,而射流出射条件如速度大小、速度分布形式以及湍流参数等因素都会影响射流特性。另外建筑的空间形式、障碍物等受限条件也会对吹吸流场特性产生重要影响。对于这些参数的影响,现有的方法通常是依靠实验和数值计算来获得不同参数下的速度场、温度场等并对这些参数进行优化。为了提高吹吸式通风系统的基本性能、降低能耗,研究结果有待于在物理机制及理论上深入地研究与探讨。要提高吹吸式通风系统的基本性能、降低能耗,需要降低周边环境空气的卷入量,而通常吹风口送风气流与环境空气是相同的介质,为揭示送风气流与环境空气共同作用下的流场特性,文中提出了标识不同来源同质流体的方法一一传质法；采用射流经典实验曲线和分析解对传质法进行了验证,证实了标识不同来源同质流体的传质法的有效性；并给出了传质法的应用实例。射流特性是影响吹吸流场特性的重要因素。基于传质法通过数值模拟的方法得到了射流出射速度大小、速度分布形式以及湍流参数对射流掺混、卷吸特性的影响,通过场协同理论对这些影响因素进行了理论分析,揭示了射流流场传质强化或弱化的方向。提出吹吸式通风系统性能系数指标来评估吹吸式通风系统的基本性能。基于传质法通过数值模拟的方法得到了吹吸式通风系统中送风口速度大小、速度分布、湍流参数以及送风口尺寸等因素对送风气流与环境空气的掺混、卷吸特性、系统基本性能系数和能耗的影响,通过场协同理论对这些影响因素进行了理论分析,得到了吹吸流场传质弱化的规律性认识,为指导吹吸式通风系统的设计提供了理论依据。障碍物会对吹吸式通风系统流场特性产生重要影响。障碍物的存在使射流发生偏转,可能使射流逃逸,影响吹吸式通风系统的基本性能；另外绕流障碍物后,障碍物周围和尾部会产生回流区,污染物一旦进入容易堆积,在实际应用中要避免将污染源放置在回流区内以及操作工人应尽量减少在此区域作业。基于传质法通过实验与数值模拟的方法,研究了障碍物位置以及障碍物尺寸对吹吸流场特性、吹吸式通风系统基本性能系数等的影响,得到了障碍物位置与障碍物尺寸对吹吸式通风系统基本性能系数、障碍物后低速区、回流区影响的规律；给出了障碍物后低速区长度、回流区长度的拟合关系式,为工程应用提供一定的参考。
[Abstract]:With the rapid development of economy, industrial buildings, indoor pollution control problems have become increasingly prominent, efficient ventilation technology is an important way to realize energy saving and emission reduction, improve the working environment and reduce air pollution. The push-pull ventilation system is an effective ventilation mode. Because of many kinds of pollution sources, pollution sources of different properties, push-pull ventilation system the design is not for some specific pollutants, but assumed by the jet control and pollutant transport, air is assumed control of the control of pollutants, so the basic performance of push-pull ventilation system refers to the control performance of the flow field, improve the basic performance by changing the suction flow characteristics. To improve the characteristics of jet blowing and suction flow characteristics a major influence, and the jet exit conditions such as velocity, velocity distribution and turbulence parameters and other factors will affect the jet characteristics. In addition the empty building Among the forms, obstacles and other constraints will have great influence on the effect of blowing and suction flow characteristics. For these parameters, the existing methods usually rely on velocity field experiment and numerical calculation to obtain different parameters, the temperature field and the parameters were optimized. In order to improve the basic performance, high push-pull ventilation system to reduce energy consumption, the results need to be in the physical mechanism and theory research and explore deeply.
In order to improve the basic performance of push-pull ventilation system to reduce energy consumption, reduce the amount of need involved in ambient air, and the air flow is blowing and air is the same as the medium, the characteristics of flow field under the action of air supply and air shows, this paper proposes a method for identifying different sources of homogeneous fluid mass transfer method; solution to verify the mass transfer method using jet classical experimental curve and analysis, confirmed the validity of the mass transfer method to identify the different sources of homogeneous fluid; mass transfer method and application examples are given.
Is an important factor affecting the characteristics of jet blowing suction flow characteristics. The mass transfer method by numerical simulation based on the jet exit velocity, the jet mixing and turbulence parameters affect the velocity distribution, volume absorption characteristic, through the field synergy theory provides a theoretical analysis of these factors, reveals the flow and mass transfer enhancement or weaken the direction.
The air suction performance index system to evaluate the performance of basic ventilation push-pull ventilation system. The mass transfer method by numerical simulation based on the inlet velocity, feed push-pull ventilation system in the velocity distribution, turbulence parameters and the air outlet size and other factors on the airflow and air mixing and entrainment characteristics. Influence of system coefficient of performance and energy consumption, through the field synergy theory provides a theoretical analysis of these factors, the regularity of flow field weakening suction mass transfer knowledge, provides a theoretical basis for guiding the design of push-pull ventilation system.
The obstacles will have an important impact on the flow characteristics of blow suction ventilation system. The obstacle to jet deflection, may make the jet escape, influence of basic properties of push-pull ventilation system; also the flow around an obstacle after obstacle around and tail will produce recirculation zone, pollutants once accumulated easily in practice. Application to avoid the pollution source placed in the recirculation region and the operation of workers should be minimized in this area. Operation method based on mass transfer was simulated by experiment and numerical study, the position of the obstacle and the obstacle size on the suction flow characteristics, influence of push-pull ventilation system coefficient of performance, the location of obstacles. And the obstacle size of push-pull ventilation system coefficient of performance, obstacle after low velocity zone, the influence of the length of the recirculation zone; low velocity zone gives the obstacle after the length of the recirculation zone The fitting formula provides some reference for the engineering application.

【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU834

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