Optimum jet-to-jet spacing of heat transfer for staggered arrays of impinging air jets

San, Jung‐Yang; Lai, Maode

doi:10.1016/s0017-9310(01)00043-6

Cited by 139 publications

(52 citation statements)

References 18 publications

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“…19 (b), the black color line denotes the distribution of R mean , the red one, R rms . In the previous paper s( San and Lai , 2001;Weigand and Spring, 2011 , it has been pointed out that MIJ reduces the heat transfer performance due to the occurrence of recirculation flow, jet-jet interaction and so on compared to SIJ, In the present study, the most narrower case reduces the performance by 60 % of SIJ , while the performance of MIJ is recovered by 80% of SIJ with increasing the jet-to-jet spacing. On the other hand, since the jet is divided into the four corer of the interaction region, for the all case of MIJ, R rms is lower than unity, that is, the homogeneity of heat transfer is attained compared to the SIJ.…”

Section: Fig 8 Contour Of Instantaneous Velocity Magnitudesupporting

confidence: 48%

“…In the outer of the jet, the white color region corresponding high heat performance region extend under the RC1 On the other hand in the interaction region, it confirms that the warm color region correlates to the recirculating flow, RC2, while the cold color region exits under the upwash flow. In the previous studies (San and Lai , 2001;Weigand and Spring, 2011 , the recirculating flow is considered to reduce the heat transfer, however, in the interference region it is found that the extension of recirculation region suppress the reduction of heat transfer performance and enhances the homogeneity of heat transfer.…”

Section: Fig 8 Contour Of Instantaneous Velocity Magnitudementioning

confidence: 99%

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DNS analysis of multiple impinging jets

Koide

Tsujimoto

Shakouchi

et al. 2014

JFST

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] IntroductionImpinging jet is widely used for cooling of industrial applications such as electric device, blades of gas turbine, hot steel and so on, since it possesses high performance of heat transfer rate and is easier to implement into various system. Their characteristics are reviewed by a few notable literatures (Kataoka, 1990 ;Viskanta, 1993). So far, a few or several ten thousand Reynolds number, defined with inlet nozzle diameter, are mainly targeted in laboratory research. However, according to the downsizing of electronic equipments, several one hundred of Re numbers are going to be dealt with (Lee, et al., 2008). Impinging jets are subdivided into three regions, such as free jet region, stagnation region and wall jet region (Viskanta,1993). Their performance of heat transfer on the impinging wall is depending on the Re number, the shape of nozzle, the number of nozzle, the distance between the nozzle and the impinging wall and so on (Viskanta,1993). In particular, although a single impinging jet produces high heat transfer rate around an impinging position on an impinging wall, however the heat transfer performance decays with increasing the distance from the impinging position. Thus in order to overcome the shortcoming of single impinging jet (SIJ), i.e., the occurrence of both inhomogeneous heat distribution on the wall and the narrow heating area, multiple impinging jets (MIJ) are generally introduced in industrial applications. Thus far it is well-known that each jet of MIJ interacts with each other, producing the complex flow field (Geers, Hanjalić, and Tummers, 2006;Weigand and Spring, 2011). In addition, the heat transfer performance is significantly influenced with their interaction. Therefore to realize an optimum heat transfer performance, the influence of geometrical arrangement of jets, i.e., the separation length between jets, the arrangement pattern, should be investigated.Recently significant advances of computer power lead to the realization of fluid phenomena including miniature vortices through the direct numerical simulation (DNS). Under the state of the art, we found the effectiveness of the active control of a round jet for the mixing enhancement (Tsujimoto, et al., 2008). Also DNS of impinging jets are conducted so far (Tsubokura, et al., 2003;Hattori and Nagano, 2004) and highly resolved LES ( large eddy simulation ) (Hadžiabdić, and Hanjalić, 2007) has demonstrated the flow structure and the statistical properties of heat transfer. Hence at present it is capable of investigating systematically the effect of control parameter. AbstractIn order to elucidate the heat and flow characteristics of multiple impinging jet (MIJ), we conduct the DNS (direct numerical simulation) of four round impinging jet arranged at an inflow of flow field. To realize the high accurate computation, the discretization in space is performed with hybrid scheme in which sine or cosine series and 6th order compact scheme are used. For the surrounding boundary condition, in order to reduce the artificial n...

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Section: Fig 8 Contour Of Instantaneous Velocity Magnitudesupporting

confidence: 48%

Section: Fig 8 Contour Of Instantaneous Velocity Magnitudementioning

confidence: 99%

DNS analysis of multiple impinging jets

Koide

Tsujimoto

Shakouchi

et al. 2014

JFST

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“…They found that the averaged Nusselt number value for H/d ¼ 2 is the highest with the value for H/d ¼ 4 being the lowest. San and Lai [7] investigated the influence of the jet-to-jet spacing on the staggered impingement heat transfer performance. The comparisons are based on the stagnation values.…”

Section: Introductionmentioning

confidence: 99%

Optimum Jet-to-Plate Spacing of Inline Impingement Heat Transfer for Different Crossflow Schemes

Xing

2013

Journal of Heat Transfer

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A nine-by-nine jet array impinging on a flat plate at Reynolds numbers from 15,000 to 35,000 has been studied by the transient liquid crystal method. The spacing between the impingement plate and target plate is adjusted to be 1, 2, 3, 4, and 5 jet diameters. The effect of jet-to-plate spacing has been investigated for three jet-induced crossflow schemes, referred as minimum, medium, and maximum crossflow, correspondingly. The local air jet temperature is measured at several positions on the impingement plate to account for an appropriate reference temperature of the heat transfer coefficient. The jetto-plate spacing, H/d ¼ 3, is found to be better than the others for all the crossflow schemes. Jet-to-plate spacings H/d ¼ 1 and H/d ¼ 2 result in a sudden decrease in the stagnation zone. The large jet-to-plate spacings H/d ¼ 4 and H/d ¼ 5 could not provide higher heat transfer performance with higher crossflow.

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“…The interaction (or interference) between D, H, S and V is qualitatively well known (1). Not the same can be said about the interaction between Sp and the other four parameters.…”

Section: Doe Matrix and Cfd Modelmentioning

confidence: 99%