High-Fidelity Simulations of Multi-Jet Impingement Cooling Flows

2021 ◽  
Author(s):  
Jose Javier Otero ◽  
Richard D Sandberg ◽  
Satoshi Mizukami ◽  
Koichi Tanimoto
Keyword(s):  
Jet Impingement ◽  
High Fidelity ◽  
Impingement Cooling ◽  
Cooling Flows ◽  
High Fidelity Simulations

High-Fidelity Simulations of Multi-Jet Impingement Cooling Flows

2020 ◽  
Author(s):  
J. Javier Otero-Pérez ◽  
Richard D. Sandberg ◽  
Satoshi Mizukami ◽  
Koichi Tanimoto
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Cross Flow ◽  
Distance Effect ◽  
Jet Impingement ◽  
Impingement Cooling ◽  
Cooling Flows ◽  
Turbulent Inflow ◽  
The Cross ◽  
Flow Effects

Abstract This article shows the first parametric study on turbulent multi-jet impingement cooling flows using large-eddy simulations (LES). We focus on assessing the influence of the inter-jet distance and the cross-flow conditions on the heat transfer at the impingement wall. The LES setup is thoroughly validated with both experimental and direct numerical simulation data, showing an excellent agreement. The inter-jet distance effect on the heat transfer is studied comparing three different distances, where the full Nusselt number profile decreases in amplitude when the jet distance is increased. To evaluate the cross-flow effects, we prescribe both laminar and turbulent inflow conditions at different cross-flow magnitudes ranging between 20% and 40% of the impinging jet speed. Large cross-flow intensities cause a jet deflection which reduces the maxima in the Nusselt number distribution, and it increases the heat transfer in the areas of the wall less affected by the jet impingement. Adding realistic turbulent fluctuations to the inflow enhances the cross-flow effects on the heat transfer at the impingement wall.

High-fidelity simulations of multi-jet impingement cooling flows

2021 ◽  
pp. 1-21
Author(s):  
Jose Javier Otero Perez ◽  
Richard Sandberg ◽  
Satoshi Mizukami ◽  
Koichi Tanimoto
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Cross Flow ◽  
Distance Effect ◽  
Jet Impingement ◽  
Impingement Cooling ◽  
Cooling Flows ◽  
Turbulent Inflow ◽  
The Cross ◽  
Flow Effects

Abstract This article shows the first parametric study on turbulent multi-jet impingement cooling flows using large-eddy simulations (LES). We focus on assessing the influence of the inter-jet distance and the cross-flow conditions on the heat transfer at the impingement wall. The LES setup is thoroughly validated with both experimental and direct numerical simulation data, showing an excellent agreement. The inter-jet distance effect on the heat transfer is studied comparing three different distances, where the full Nusselt number profile decreases in amplitude when the jet distance is increased. To evaluate the cross-flow effects, we prescribe both laminar and turbulent inflow conditions at different cross-flow magnitudes ranging between 20% and 40% of the impinging jet speed. Large cross-flow intensities cause a jet deflection which reduces the maxima in the Nusselt number distribution, and it increases the heat transfer in the areas of the wall less affected by the jet impingement. Adding realistic turbulent fluctuations to the inflow enhances the cross-flow effects on the heat transfer at the impingement wall.

3-D Visualization of Flow in Microscale Jet Impingement System

2009 ◽  
Author(s):  
Yoon Jin Won ◽  
Milnes David ◽  
Evelyn N. Wang ◽  
Kenneth E. Goodson ◽  
Thomas W. Kenny
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Two Dimensional ◽  
Impingement Cooling ◽  
Cooling Flows ◽  
Enhancing Heat Transfer ◽  
Predictive Design ◽  
Impingement Surface

This paper presents our recent work on the reconstruction of three-dimensional (3-D) flow fields in a microscale jet impingement cooling flows. We use micron-resolution PIV to capture successive two-dimensional (2-D) “slices” of the flow field in a 3-D structure, and compare with models of flow near microscale jets. This approach is specifically constructed to determine the z-component of the flow velocities, which play a key role in enhancing heat transfer at the impingement surface. These new results will enable a predictive design capability for microjet impingement cooling structures for high power electronics.

Jet impingement cooling of triangular ribbed surface with bottom exit grill ( Category-Engineering )

2011 ◽  
Vol 3 (2) ◽  
pp. 136-137
Author(s):  
Dr. M.T. Bhoite Dr. M.T. Bhoite ◽  
◽  
Kartik Jujare ◽  
Sayali Wable
Keyword(s):  
Jet Impingement ◽  
Impingement Cooling

Heat Transfer Characteristics of Downward Facing Hot Horizontal Surfaces Using Mist Jet Impingement

2017 ◽  
Author(s):  
Ashutosh Kumar Yadav ◽  
Parantak Sharma ◽  
Avadhesh Kumar Sharma ◽  
Mayank Modak ◽  
Vishal Nirgude ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Cooling System ◽  
Water Pressure ◽  
Jet Impingement ◽  
Surface Heat ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
Transfer Characteristics

Impinging jet cooling technique has been widely used extensively in various industrial processes, namely, cooling and drying of films and papers, processing of metals and glasses, cooling of gas turbine blades and most recently cooling of various components of electronic devices. Due to high heat removal rate the jet impingement cooling of the hot surfaces is being used in nuclear industries. During the loss of coolant accidents (LOCA) in nuclear power plant, an emergency core cooling system (ECCS) cool the cluster of clad tubes using consisting of fuel rods. Controlled cooling, as an important procedure of thermal-mechanical control processing technology, is helpful to improve the microstructure and mechanical properties of steel. In industries for heat transfer efficiency and homogeneous cooling performance which usually requires a jet impingement with improved heat transfer capacity and controllability. It provides better cooling in comparison to air. Rapid quenching by water jet, sometimes, may lead to formation of cracks and poor ductility to the quenched surface. Spray and mist jet impingement offers an alternative method to uncontrolled rapid cooling, particularly in steel and electronics industries. Mist jet impingement cooling of downward facing hot surface has not been extensively studied in the literature. The present experimental study analyzes the heat transfer characteristics a 0.15mm thick hot horizontal stainless steel (SS-304) foil using Internal mixing full cone (spray angle 20 deg) mist nozzle from the bottom side. Experiments have been performed for the varied range of water pressure (0.7–4.0 bar) and air pressure (0.4–5.8 bar). The effect of water and air inlet pressures, on the surface heat flux has been examined in this study. The maximum surface heat flux is achieved at stagnation point and is not affected by the change in nozzle to plate distance, Air and Water flow rates.

scholarly journals Peering inside a cough or sneeze to explain enhanced airborne transmission under dry weather

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kai Liu ◽  
Majid Allahyari ◽  
Jorge S. Salinas ◽  
Nadim Zgheib ◽  
S. Balachandar
Keyword(s):  
High Fidelity ◽  
Substantial Variation ◽  
Ambient Conditions ◽  
Airborne Transmission ◽  
Social Distancing ◽  
Virtual Experiments ◽  
Long Time ◽  
Simulation Results ◽  
High Fidelity Simulations ◽  
Droplet Nuclei

AbstractHigh-fidelity simulations of coughs and sneezes that serve as virtual experiments are presented, and they offer an unprecedented opportunity to peer into the chaotic evolution of the resulting airborne droplet clouds. While larger droplets quickly fall-out of the cloud, smaller droplets evaporate rapidly. The non-volatiles remain airborne as droplet nuclei for a long time to be transported over long distances. The substantial variation observed between the different realizations has important social distancing implications, since probabilistic outlier-events do occur and may need to be taken into account when assessing the risk of contagion. Contrary to common expectations, we observe dry ambient conditions to increase by more than four times the number of airborne potentially virus-laden nuclei, as a result of reduced droplet fall-out through rapid evaporation. The simulation results are used to validate and calibrate a comprehensive multiphase theory, which is then used to predict the spread of airborne nuclei under a wide variety of ambient conditions.

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