Heat transfer under composite arrangement of pulsed and steady turbulent submerged multiple jets impinging on a flat surface

Mohammadpour, Javad; Zolfagharian, Mohammad Mehdi; Mujumdar, Arun S.; Zargarabadi, Mehran Rajabi; Abdulahzadeh, Mohammad

doi:10.1016/j.ijthermalsci.2014.07.004

Cited by 38 publications

(9 citation statements)

References 21 publications

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“…As direct numerical simulation (DNS) and large eddy simulation (LES) demand increasing computation capabilities, most researchers prefer to use Reynolds‐averaged Navier–Stokes (RANS) equations to achieve satisfactory flow and noise results. [ 47–49 ] In terms of acoustic calculations, the Ffowcs Williams–Hawkings (FW‐H) integral equation, which is based on the Lighthill acoustic analogy, considers the influence of the wall surface. [ 50–52 ] This represents several advantages over other acoustic models in the numerical calculations related to the jet impinging noise.…”

Section: Mathematical Modeling and Numerical Methodsmentioning

confidence: 99%

Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

Liu

Xiang

et al. 2020

steel research int.

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Scarfing applications cause severe noise pollution in metallurgical engineering. To determine the noise characteristics generated by parallel multiple impinging jets in the slab scarfing process, a physical experiment is performed, and a 3D mathematical model is established. Mutual attraction of the parallel multiple jets is recorded, and its influence on the acoustic properties is revealed. The effects of impact height, impact angle, and Reynolds number on the multi‐jet impingement are analyzed. The results indicate that the parallel multiple jets combine in pairs in the upstream. The multi‐jet impingement increases the magnitude of dipole acoustic source, and the noise directivity presents two peaks above the impacted surface. As the impact height increases, the noise intensity first increases to later decrease, and the noise propagation is deflected along the axial direction. As the impact angle decreases, the noise intensity gradually increases, and the spectrum shifts toward higher frequencies. The jet Reynolds number only affects the noise intensity, but has little influence on the spectrum and directivity. The results of this research may provide a theoretical basis for the formulation of guidelines to reduce noise pollution in slab scarfing processes.

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Section: Mathematical Modeling and Numerical Methodsmentioning

confidence: 99%

Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

Liu

Xiang

et al. 2020

steel research int.

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“…Such Lagrange multiplier, needed for the computation of the gradient equation (as will be apparent below), is obtained through the solution of a problem adjoint to the sensitivity problem is given by Eq. (19). In order to derive the adjoint problem, we write the following extended function:…”

Section: Limits Of Designmentioning

confidence: 99%

“…Based on his results, heat transfer of two oscillating slot jets with phase difference of p/2 could be improved greatly compared to the use of conventional steady jets. Mohammad Pour et al [19] examined numerically an optimized arrangement of steady and pulsating impinging multiple submerged slot jets. A composite design consisting of steady as well as intermittent (on/off) or sinusoidal (outlet jet velocity magnitude changes with time sinusoidal) jets in different combinations of four slot jets was simulated.…”

Section: Introductionmentioning

confidence: 99%

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Optimization Arrangement of Two Pulsating Impingement Slot Jets for Achieving Heat Transfer Coefficient Uniformity

Farahani

Bijarchi

Kowsary

et al. 2016

Journal of Heat Transfer

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In this paper, an optimization was performed to achieve uniform distribution of convective heat transfer coefficient over a target plate using two impinging slot (air) jets. The objective function is the root mean square error (Erms) of the local Nusselt distribution computed by computational fluid dynamic (CFD) simulations from desired Nusselt numbers. This pattern search minimized this objective function. Design variables are nozzle widths, jet-to-jet distance, jet-to-target plate distance, frequency of pulsations (for pulsating jets), and the flow rate. First, an inverse design is performed for two steady jets for simplicity and the obtained errors for three different desired Nusselt numbers, NuD = 7, 10, and 13, were 20.73%, 20.08%, and 22.92%, respectively. Uniform distribution of heat transfer coefficient for two steady jets was not achieved. Thus, two pulsating jets are considered. The range of design variables for pulsating state is as same as steady-state and heat transfer rates increased about 400% over steady-state due to the effects of pulsations in inlet velocity. Thus, in the pulsating state, optimization must be performed for the desired Nusselt numbers around four-times NuD in the steady-state, i.e., NuD = 28, 40, and 52. The Erms reduced less than 0.01% and distribution of heat transfer coefficient for all cases was uniform. An experimental study using an inverse heat conduction method (conjugate gradient method with adjoint equation) has been performed and the experimental results for the case of NuD = 52 are presented. The estimated distribution of Nusselt number on the target plate with the numerical distribution has around 3.2% relative error with optimal configuration.

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“…They found that a turbulent slot jet with intermittent waves provided higher heat transfer than sinusoidal waves. Hadipour et al [8] studied flow and heat transfer characteristics of jet impingement on a concave surface. They revealed that the jet-to-surface distance of H/d=0.1 was superior to other ratios in terms of steady jet heat transfer.…”

Section: Introductionmentioning

confidence: 99%

A detailed analysis of flow and heat transfer characteristics under a turbulent intermittent jet impingement on a concave surface

2022

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A computational study is carried out of the three-dimensional flow field and heat transfer under a turbulent intermittent circular jet impingement on a concave surface. The control-volume procedure with the SIMPLE algorithm is employed to solve the unsteady RANS (use full form) equations. The RNG k-? model is implemented to simulate turbulence due to its success in predicting similar flows. The numerical results are validated by comparing them with the experimental data. The effects of jet Reynolds number and oscillation frequency on the flow and heat transfer are evaluated. The profiles of instantaneous and time-averaged Nusselt numbers exhibit different trends in axial (x) and circumferential (s) directions. It is found that increasing frequency from 50 to 200 Hz results in considerable time-averaged Nusselt number enhancement in both axial and curvature directions. The intermittent jet at a frequency of 200 Hz enhances the total average Nusselt number by 51.4%, 40%, and 33.7% compared to the steady jet values at jet Reynolds numbers of 10000, 23000, and 40000, respectively. In addition, a correlation for the average Nusselt number is proposed depending on the Reynolds number and the Strouhal number.

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Heat transfer under composite arrangement of pulsed and steady turbulent submerged multiple jets impinging on a flat surface

Cited by 38 publications

References 21 publications

Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

Optimization Arrangement of Two Pulsating Impingement Slot Jets for Achieving Heat Transfer Coefficient Uniformity

A detailed analysis of flow and heat transfer characteristics under a turbulent intermittent jet impingement on a concave surface

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