Experimental investigation of near-field stream-wise flow development and spatial structure in triple buoyant plumes
2019 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 149, p. 79-89Article in journal (Refereed) Published
Abstract [en]
This paper presents a systematic experimental study on stream-wise flow development and spatial structure of triple buoyant plumes. Two-dimensional Particle Image Velocimetry (2-D PIV) is employed to resolve velocity fields. Stream-wise axial velocity profiles, flow structure, flow region parameters, and self-similarity properties are analyzed at different configurations that are characterized by spacing ratios S/W (source spacing S divided by source width W). From velocity fields and axial velocity profiles, a similar stream-wise developing trend is identified in different source configurations. When near-field plumes travel downstream, axial velocities increase rapidly, off-center velocity peaks get merged with the central peak, and the number of velocity peaks reduces with the downstream distance. A compact source layout, comparing with the wide one, could enhance the near-field plumes interaction and promote the plumes deflection significantly. Fundamentally, the stream-wise spatial structure of the triple plumes initially consists of a converging region, followed by a merging region, and finally a combined region. By examining the averaged velocity fields, flow recirculation with negative axial velocities is found to scarcely exist in the converging region. Merging level Zm and quasi-combined level Zqc are analyzed quantitatively and statistically. Within the studied S/W range, the normalized Zm shows a linear increase with S/W in the formula of Zm/H=2.007(S/W)+1.173 and the normalized Zqc gives a power law increase with S/W in the formula of Zqc/H=6.035(S/W)0.4959. In addition, triple plumes are found to establish self-similarity approximately at Z = 3H with S/W of 0.2 and at Z = 4.5H with S/W of 0.5.
Place, publisher, year, edition, pages
Elsevier Ltd , 2019. Vol. 149, p. 79-89
Keywords [en]
Merging level, Quasi-combined level, Self-similarity, Source spacing, Spatial structure, Stream-wise flow development, Merging, Velocity, Velocity measurement, Flow development, Self-similarities, Buoyancy
National Category
Mechanical Engineering
Research subject
Sustainable Urban Development
Identifiers
URN: urn:nbn:se:hig:diva-29063DOI: 10.1016/j.buildenv.2018.11.039ISI: 000457118300008Scopus ID: 2-s2.0-85058185482OAI: oai:DiVA.org:hig-29063DiVA, id: diva2:1275821
Note
Funding Agency:
RGC GRF project of the Hong Kong SAR Government Grant no: 17201817
2019-01-072019-01-072021-02-17Bibliographically approved