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首页> 外文期刊>International Journal of Heat and Mass Transfer >Influence of source conditions and heat losses on the upwind back-layering flow in a longitudinally ventilated tunnel
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Influence of source conditions and heat losses on the upwind back-layering flow in a longitudinally ventilated tunnel

机译：源条件和热损失对纵向通风隧道中逆风层流的影响

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摘要

We study experimentally the dynamics of a back-layering flow developing below the ceiling of a longitudinally ventilated tunnel, and induced by the presence of a steady source of buoyancy at the tunnel floor. Our aim is to identify the dependence of the longitudinal extent of the back-layering flow upwind of the source (and therefore against the tunnel ventilation velocity) as a function of the parameters characterising the buoyant release at the source and of those characterising the thermal losses at the tunnel ceiling. To this end purpose we performed experiments in two different reduced scale models, using helium and hot air as buoyant fluids. Based on the experimental results, we develop a semi-empirical model for the prediction of the (non-dimensional) extent of the back-layering flow. This can be expressed as a function of three non-dimensional parameters. The first one is the tunnel Richardson number Ri, expressing the ratio between the buoyancy effects induced by the source and the inertia effects of the tunnel ventilation. The second is its critical value Ri_c, obtained by imposing the so-called critical ventilation velocity, preventing the formation of a back-layer flow upstream of the source. The third parameter, referred to as λ~*_r, characterises the heat losses at the tunnel walls. The variability of the conditions imposed at the source, namely the momentum flux related to the injection of buoyant fluid, have negligible influence on the critical condition and therefore on the extent of the back-layering flow (which depends therefore on the buoyancy flux at the source, only). In contrast, the heat losses play instead a major role, which results in a relevant reduction of the back-layering flow that can be five times shorter than in the adiabatic case.
机译：我们通过实验研究了在纵向通风隧道的顶棚下方发展的，由隧道底部存在稳定浮力源引起的背层流的动力学。我们的目的是根据表示源头浮力释放的参数和表示热损失的参数的函数，确定源头逆流的上层气流纵向范围的依赖性（并因此与隧道通风速度有关）。在隧道的天花板上。为此，我们在两个不同的缩小比例模型中进行了实验，使用氦气和热空气作为浮力液。基于实验结果，我们开发了一个半经验模型来预测背向流动的（无量纲）程度。这可以表示为三个无量纲参数的函数。第一个是隧道的Richardson数Ri，表示源引起的浮力效应与隧道通风的惯性效应之比。第二个是其临界值Ri_c，它是通过施加所谓的临界通风速度而获得的，从而防止了在源上游形成背流。第三个参数称为λ〜* _r，表示隧道壁处的热损失。施加在源头的条件的可变性，即与注入浮力流体有关的动量通量，对临界条件的影响可以忽略不计，因此对背向流动程度的影响也可以忽略不计（因此，取决于背压层的浮力通量）。来源）。相反，热损失起主要作用，这导致背层流动的相应减少，其可以比绝热情况下短五倍。

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  • 作者

    P. Salizzoni; M. Creyssels; L. Jiang; A. Mos; R. Mehaddi; O. Vauquelin;

  • 作者单位

    Laboratoire de Mecanique des Fluides et d'Acoustique, UMR CNRS 5509, University of Lyon - Ecole Centrale de Lyon, INSA Lyon, University Claude Bernard Lyon I, 36, Avenue Guy de Collongue, 69134 Ecully CEDEX, France;

    Laboratoire de Mecanique des Fluides et d'Acoustique, UMR CNRS 5509, University of Lyon - Ecole Centrale de Lyon, INSA Lyon, University Claude Bernard Lyon I, 36, Avenue Guy de Collongue, 69134 Ecully CEDEX, France;

    Laboratoire de Mecanique des Fluides et d'Acoustique, UMR CNRS 5509, University of Lyon - Ecole Centrale de Lyon, INSA Lyon, University Claude Bernard Lyon I, 36, Avenue Guy de Collongue, 69134 Ecully CEDEX, France;

    Centre d'Erudes des Tunnels, 25 Avenue Francois Mitterrand, Case n°1, 69674 Bron, France;

    Universite de Lorraine, CNRS, LEMTA UMR 7563, 54 518 Vandoeuvre-les-Nancy, France;

    Aix Marseille Universiti, CNRS, IUST1 UMR 7343, 13 453 Marseille, France;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Buoyant flows; Turbulent plumes; Back-layering; Tunnel ventilation; Heat transfer;

    机译：浮流;湍急的羽状流;背层;隧道通风;传播热量;

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