Experimental study on turbulent mixing process in cross-flow type T-junction

Hirota, Masafumi; Mohri, E.; Asano, Hideo; Goto, Hiroki

doi:10.1615/ichmt.2009.turbulheatmasstransf.2120

Cited by 7 publications

(10 citation statements)

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“…The vertical branch channel was joined to the horizontal main channel at right angles to form a T-junction. The specification of this channel was essentially the same as that used in our preceding study (Hirota, et al, 2010) except that the second edge (edge in the downstream side) of the T-junction was planed off. We chamfered this second edge because high turbulence caused by the flow separation at this sharp edge was located below the thermal mixing layer, and did not contribute so much to the turbulent thermal mixing of two flows (Hirota, et al, 2008).…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…The cross-flow type mixing T-junction is also found in the HVAC (Heating, Ventilating and Air-conditioning) unit used for an automobile air-conditioning system. Figure 1 shows a cross-sectional view of the automobile HVAC unit, which contains a fan, an evaporator and a heater-core in a plastic housing (Kitada, et al, 2000, Hirota, et al, 2010. All air taken by the fan is once cooled by the evaporator and humidity is reduced as well, then a part of this cold air is heated by the heater-core.…”

Section: Introductionmentioning

confidence: 99%

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Promotion and control of turbulent mixing of hot and cold airflows in T-junction

Matsuda

Hirota

Asano

et al. 2014

JFST

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An experimental study was conducted on the promotion and control of turbulent mixing of hot and cold airflows in a rectangular channel with a T-junction, which simulated an HVAC unit for automobile air-conditioning system. A delta-wing row was installed on the bottom wall of the main channel before the T-junction to promote and control the turbulent thermal mixing. The mean temperature and velocity distributions were measured in several cross sections after the flow merging by thermocouples and PIV, respectively, and the flow in the mixing region was visually observed as well. The development of the thermal mixing layer was promoted effectively by delta wings and the degree of thermal mixing could be controlled by changing the angle of attack of wings. Longitudinal vortices produced by delta wings disappeared just after the merging of two flows, but high turbulence generated by the interaction of those vortices and the branch flow was maintained to further downstream cross sections. The proper orthogonal decomposition analysis was applied to the fluctuating concentration and the fluctuating velocity fields to extract the dominant spatial structures in the T-junction. It was suggested that longitudinal vortices with clockwise and counter-clockwise rotations were shed alternately just behind each delta wing.

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Section: Experimental Apparatusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Promotion and control of turbulent mixing of hot and cold airflows in T-junction

Matsuda

Hirota

Asano

et al. 2014

JFST

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“…Such a kind of flow regime is similar to that reported in previous literature. 6 Among these features, RZ1 contains the highest vorticity. Therefore, it is expected to be the major source of flow unsteadiness.…”

Section: Mean Flowsmentioning

confidence: 99%

“…On the other hand, the focus of the reported research of merging flow is usually put on the flow dynamics, rather than its aeroacoustics, e.g., the work of Br€ ucker 5 in the regime of laminar flow. For higher Reynolds number flow regime, Hirota et al 6 examined the merging of cold and hot air streams at T-junction experimentally (Re % 10 4 ). Their major focus is the heat transfer between the inlet flows, so only some flow characteristics are discussed in their paper.…”

Section: Introductionmentioning

confidence: 99%

Aeroacoustics of T-junction merging flow

Lam

Leung

Tang

2013

The Journal of the Acoustical Society of America

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This paper reports a numerical study of the aeroacoustics of merging flow at T-junction. The primary focus is to elucidate the acoustic generation by the flow unsteadiness. The study is conducted by performing direct aeroacoustic simulation approach, which solves the unsteady compressible Navier-Stokes equations and the perfect gas equation of state simultaneously using the conservation element and solution element method. For practical flows, the Reynolds number based on duct width is usually quite high (>10(5)). In order to properly account for the effects of flow turbulence, a large eddy simulation methodology together with a wall modeling derived from the classical logarithm wall law is adopted. The numerical simulations are performed in two dimensions and the acoustic generation physics at different ratios of side-branch to main duct flow velocities VR (=0.5,0.67,1.0,2.0) are studied. Both the levels of unsteady interactions of merging flow structures and the efficiency of acoustic generation are observed to increase with VR. Based on Curle's analogy, the major acoustic source is found to be the fluctuating wall pressure induced by the flow unsteadiness occurred in the downstream branch. A scaling between the wall fluctuating force and the efficiency of the acoustic generation is also derived.

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“…Only a few studies have been focused on this topic and mainly for periodic turbulent forced flows where simultaneous measurements are not necessary [1]. In 1994, Tholet and Bogard [2] considered the simultaneous temperature and velocity measurements in order to determine turbulent heat fluxes and temperature-velocity correlation coefficients.…”

Section: Introductionmentioning

confidence: 99%