横流中圆形高架射流的射流剪切层特征

IF 2.8 2区 工程技术 Q2 ENGINEERING, MECHANICAL
Jyoti Gupta, Arun K. Saha
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引用次数: 0

摘要

本研究旨在通过实验研究速度比 (R) 对高宽比 (AR) 为 9.0 的烟囱在雷诺数为 2000 的均匀横流中喷出的高架圆形射流的演变的影响。实验在低速再循环水隧道中进行。采用激光多普勒测速仪(LDV)对水隧道进行表征。粒子图像测速仪(PIV)用于测量流场,染料可视化技术用于捕捉伴随的瞬时流动结构。根据速度比(R = 0.16 - 1.5)的不同,在对称平面(XY)上可观察到明显的喷射剪切层(JSL)结构,这一点已被流动可视化和 PIV 数据所证实。这些结构包括顺时针漩涡、逆时针漩涡、摆动引起的蘑菇状漩涡和喷流状漩涡。在 R<0.5 条件下,观察到大量喷射流体被夹带到叠渚区域(下冲)。在 R=0.5 时,在壁面平行面上捕捉到的条纹图像显示出环状涡流,这些涡流似乎围绕着喷流核心,而在喷流左侧的下游则检测到直立涡流。此外,还讨论了近场平均速度和湍流波动的变化,这取决于不同的速度比。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Characteristics of the jet shear layer of a round elevated jet in crossflow

The present research aims at an experimental study to investigate the effect of velocity ratio (R) on the evolution of elevated round jet issued from a stack having an aspect ratio (AR) of 9.0 in a uniform crossflow at a Reynolds number of 2000. The experiments are conducted in a low-speed, recirculating water tunnel. Laser Doppler Velocimetry (LDV) is employed to characterize the water tunnel. Particle Image Velocimetry (PIV) is used to measure the flow field, and the dye visualization technique is utilized to capture the accompanying instantaneous flow structures. Depending on the velocity ratio (R = 0.16 - 1.5), distinct jet shear layer (JSL) structures are observed in the symmetric plane (XY), confirmed by both the flow visualization and PIV data. These structures include clockwise vortices, anticlockwise vortices, swing-induced mushroom vortices, and jet-like vortices. For R<0.5, entrainment of a substantial amount of jet fluid into the stack-wake region (downwash) has been observed. At R=0.5, the streak image captured in the wall parallel plane reveals the ring-like vortices that appear to wrap around the jet core while upright vortices are detected downstream on the lee side of the jet. Additionally, variations in average velocity and turbulent fluctuations in the near field, contingent on different velocity ratios, are discussed.

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来源期刊
Experimental Thermal and Fluid Science
Experimental Thermal and Fluid Science 工程技术-工程:机械
CiteScore
6.70
自引率
3.10%
发文量
159
审稿时长
34 days
期刊介绍: Experimental Thermal and Fluid Science provides a forum for research emphasizing experimental work that enhances fundamental understanding of heat transfer, thermodynamics, and fluid mechanics. In addition to the principal areas of research, the journal covers research results in related fields, including combined heat and mass transfer, flows with phase transition, micro- and nano-scale systems, multiphase flow, combustion, radiative transfer, porous media, cryogenics, turbulence, and novel experimental techniques.
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