Buoyancy distribution in a filling box segmented by a planar jet
- PDF / 2,872,156 Bytes
- 23 Pages / 439.37 x 666.142 pts Page_size
- 69 Downloads / 166 Views
Buoyancy distribution in a filling box segmented by a planar jet N. Kaye1 · N. Williamson2 · D. Huang2 · S. W. Armfield2 Received: 2 June 2020 / Accepted: 9 September 2020 © Springer Nature B.V. 2020
Abstract Air curtains are produced by thin vertical planar air jets and are used to prevent exchange flows between two fluids with a horizontal density gradient. They have been shown to work effectively provided the deflection modulus (DM) is greater than a critical value (DM = 0.14). Herein, results are presented from an experimental and modeling study of the initial transient development of the buoyancy distribution within an enclosure containing a round buoyant turbulent plume that is segmented by a co-flowing planar turbulent jet. A theoretical model based on filling box theory is developed to predict the leakage of buoyant fluid across the planar jet and the time at which the planar jet is no longer able to contain the buoyant plume outflow. Results from a series of analog salt-bath experiments are also presented that show that the model accurately predicts the rate of transport of buoyant fluid across the planar jet up until DM falls below the critical value of 0.14. The experiments show that, following the breakdown of the model there is a transition period after which the horizontal distribution of buoyant fluid throughout the enclosure is the same as it would be in the absence of the planar jet. Keywords Filling box · Air curtain · Smoke control · Buoyancy
1 Introduction This paper investigates the time development of the buoyancy distribution of a filling box that is segmented by a vertical planar turbulent jet. The filling box model [1] predicts the time development of the stratification that develops in an enclosure containing a localized source of buoyancy (turbulent plume). The initial application of this model was the stratification of lakes and other finite fluid volumes. It has since been expanded to look at, for example, overturning in LNG tanks [2], and the natural ventilation of buildings [3]. An air curtain consists of a thin planar air jet that inhibits the mixing between two air bodies of different temperature across a vertical plane. Air curtains are commonly used * N. Kaye [email protected] 1
Glenn Department of Civil Engineering, Clemson University, Clemson, SC, USA
2
School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
13
Vol.:(0123456789)
Environmental Fluid Mechanics
for separating warm and cold regions of a single enclosure. Application examples include refrigerated cabinets in stores [4, 5], building entry ways [6], and cold rooms [6–9]. The advantage of using air curtains over solid barriers is that they allow people or equipment to pass through the air curtain without ‘opening’ the barrier. Typically air curtains are downward flowing planar jets as, for many applications, they are aerodynamic barriers that people walk through and it avoids high speed upward flow around people clothes. There are also logistical considerat
Data Loading...
