Dependence of submerged jet heat transfer on nozzle length

Kashi, Barak; Haustein, Herman D.

doi:10.1016/j.ijheatmasstransfer.2017.12.064

Cited by 19 publications

(5 citation statements)

References 47 publications

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“…This result indicates that the sharp inlet of the nozzle does not influence the nozzle exit velocity profiles. This result is consistent with the literature (Kashi & Haustein 2018), where it is reported that the nozzle exit velocity profiles are not influenced by a sharp inlet if ( is Reynolds number based on average velocity and nozzle diameter). For the maximum average Reynolds number () studied in the present experiments, the above condition gives , which is lower than the minimum () used in the present study.…”

Section: Resultssupporting

confidence: 93%

“…This result indicates that the sharp inlet of the nozzle does not influence the nozzle exit velocity profiles. This result is consistent with the literature (Kashi & Haustein 2018), where it is reported that the nozzle exit velocity profiles are not influenced by a sharp inlet if L/(D Re av ) > 0.0015 (Re av is Reynolds number based on average velocity and The self-similar laminar boundary layer profile (Blasius profile) is invariant, so the laminar velocity profile at the nozzle exit can be uniquely represented by D/θ 0 . The non-dimensional momentum thickness D/θ is calculated using (4.1),…”

Section: Inlet Flow Conditionsupporting

confidence: 92%

See 1 more Smart Citation

Global oscillations in low-density round jets with parabolic velocity profiles

2022

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Experiments and spatiotemporal stability analysis are carried out to study the global oscillations in laminar low-density round jets with parabolic velocity profiles. The experimental results of laminar low-density jets with parabolic velocity profiles exhibit global axisymmetric oscillations. The spatiotemporal stability results based on base profiles from numerical simulations are consistent with the present experimental results. These results differ from the prediction of stability study by Coenen et al. (Phys. Fluids, vol. 20, 2008, p. 074104). They reported that the low-density jets with near parabolic velocity profiles show global helical oscillations. It is observed that the method used by Coenen et al. is not able to predict the nature of global oscillations observed in experiments for low-density jets with near parabolic profiles. The present spatiotemporal stability results demonstrate that the base flows from Navier–Stokes equations are required to predict the critical conditions observed in experiments for low-density jets with near parabolic velocity profiles. The breakdown distance of globally unstable low-density jets scales with $(Re-Re_c)^{-1/2}$ ( $Re_c$ is the critical Reynolds number), consistent with the scaling law obtained from the nonlinear global mode of the Ginzburg–Landau equation.

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Section: Resultssupporting

confidence: 93%

“…This result indicates that the sharp inlet of the nozzle does not influence the nozzle exit velocity profiles. This result is consistent with the literature (Kashi & Haustein 2018), where it is reported that the nozzle exit velocity profiles are not influenced by a sharp inlet if L/(D Re av ) > 0.0015 (Re av is Reynolds number based on average velocity and The self-similar laminar boundary layer profile (Blasius profile) is invariant, so the laminar velocity profile at the nozzle exit can be uniquely represented by D/θ 0 . The non-dimensional momentum thickness D/θ is calculated using (4.1),…”

Section: Inlet Flow Conditionsupporting

confidence: 92%

Global oscillations in low-density round jets with parabolic velocity profiles

2022

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“…In the present work two-phase numerical solutions of the Navier-Stokes and energy equations were applied to obtain detailed descriptions of the velocity and pressure fields, as well as the wall-side heat transfer, of impinging jets in the range of Re = 600-2000. The numerical methods are described in detail in a previous work [24,27], and given here briefly. The flow was simulated with an unsteady solver until a steady velocity field was observed and verified, i.e., doubling the simulated time (up to 6.4 s) resulted in negligible change in the velocity profile (<1%).…”

Section: The Direct Heat Transfer Descriptionmentioning

confidence: 99%

Stagnation point heat transfer under a free-surface jet

Harnik,

Haustein

2024

J. Phys.: Conf. Ser.

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Laminar free-surface jet impingement is a crucial configuration for heat transfer processes. Focusing on the link between stagnation-point heat transfer and near-axis radial acceleration, its dependence on jet width and profile is studied. Thus, heat transfer depends on: fluid properties, flow rate, nozzle length, nozzle-to-plate spacing, surface tension and gravity (Pr, Re, L/d, H/d, We & Fr, accordingly). As existing theory is limited to specific cases, a new general description is developed from analogy to submerged jets. Validated by two-phase flow simulations, this description captures key jet dynamics evolution (centerline velocity, profile curvature). It reveals significant property changes during jet flight due to relaxation (L dependence) and contraction (Re/Fr dependence). Unlike submerged jets, contraction raises arrival Reynolds number, leading to additional dependencies Nu ∝ L and Nu ∝ H/Fr, and further deviations at low-We and -Re. The theory successfully predicts heat transfer across diverse conditions and converges to negligible gravity (horizontal jet) as expected.

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“…[33] eş hidrolik çapa sahip farklı formdaki jet nozülleri ile soğutulan ve yüzeyinde üçgen engeller bulunan düz bir plakadan taşınımla ısı transferini 900 ile 11000 Reynolds sayısı aralığında deneysel olarak incelemişlerdir. Kashi ve Haustein [34] akış bölgesi içerisine uzatılmış bir jet nozülünün taşınımla ısı transferine etkilerini Reynolds sayısının 500 ile 2000 aralığında sayısal olarak incelemişlerdir. Gürtürk ve Öztop [35] üzerinde gözenekli metal köpük bulunan ısıtılmış bir diskin dairesel kesitli bir jet nozülü ile soğutulmasını deneysel olarak incelemişlerdir.…”

Section: Gi̇ri̇ş (Introduction)unclassified

Elektronik Bileşenlerin Bir Çift Slot Jet ile Soğutulmasında Nozül Konumunun Soğutma Performansına Etkisi

2024

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Bu çalışmada, elektronik bileşenlerin bir çift slot jet ile soğutulmasında nozül konumunun akış yapısı ve taşınımla ısı transfer karakteristiklerine etkileri sayısal olarak incelenmiştir. Nozül genişlikleri ve jet Reynolds sayıları eşit alınarak dört farklı nozül konumu (JK 1-2, JK 1-3, JK 1-4 ve JK 1-5) için Reynolds sayısının 100 ile 500 değerleri arasında, laminer rejimde iki-boyutlu hesaplamalar gerçekleştirilmiştir. Sayısal hesaplamalar ANSYS Fluent yazılımı ile yürütülürken, farklı Reynolds sayıları ve jet konumları için hız ve sıcaklık konturları, ısı kaynaklarının yüzeylerinde yerel ve ortalama Nusselt sayılarının değişimi ve genel ortalama Nusselt sayısının değişimi incelenmiştir. Çalışma sonucunda, akış yapısı ve taşınımla ısı transfer karakteristiklerinin nozül konumundan oldukça etkilendiği, sistemin geneli için taşınımla ısı transfer hızının JK 1-2’de diğer durumlara oranla daha yüksek olduğu ve ikinci nozülün çıkışa doğru kayması ile birlikte taşınımla ısı transfer hızının sistemin geneli için azaldığı belirlenmiştir.

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Dependence of submerged jet heat transfer on nozzle length

Cited by 19 publications

References 47 publications

Global oscillations in low-density round jets with parabolic velocity profiles

Global oscillations in low-density round jets with parabolic velocity profiles

Stagnation point heat transfer under a free-surface jet

Elektronik Bileşenlerin Bir Çift Slot Jet ile Soğutulmasında Nozül Konumunun Soğutma Performansına Etkisi

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