Numerical investigation of heat transfer and flow characteristics of a double-wall cooling structure: Reverse circular jet impingement

Ahmed, Abdallah; Wright, Edward; Abdel-Aziz, F; Yan, Yuying

doi:10.1016/j.applthermaleng.2021.116720

Cited by 20 publications

(2 citation statements)

References 31 publications

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“…Note that similar to the dimples, protrusions can also lead to the same effect of heat transfer enhancement [20]. A more complex, although presumably more efficient, cooling configuration was suggested in [21], namely a double-wall cooling structure with a reverse circular jet impingement. There yet exists an alternative to the above-mentioned shape (or geometrical) enhancements of the heat transfer of jet cooling.…”

Section: Introductionmentioning

confidence: 96%

Experimental and Numerical Investigations into Heat Transfer Using a Jet Cooler in High-Pressure Die Casting

Bohacek,

Mraz,

Krutis

et al. 2023

JMMP

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During high-pressure die casting, a significant amount of heat is dissipated via the liquid-cooled channels in the die. The jet cooler, also known as the die insert or bubbler, is one of the most commonly used cooling methods. Nowadays, foundries casting engineered products rely on numerical simulations using commercial software to determine cooling efficiency, which requires precise input data. However, the literature lacks sufficient investigations to describe the spatial distribution of the heat transfer coefficient in the jet cooler. In this study, we propose a solver using the open-source CFD package OpenFOAM and free library for nonlinear optimization NLopt for the inverse heat conduction problem that returns the desired distribution of the heat transfer coefficient. The experimental temperature measurements using multiple thermocouples are considered the input data. The robustness, efficiency, and accuracy of the model are rigorously tested and confirmed. Additionally, temperature measurements of the real jet cooler are presented.

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Section: Introductionmentioning

confidence: 96%

Experimental and Numerical Investigations into Heat Transfer Using a Jet Cooler in High-Pressure Die Casting

Bohacek,

Mraz,

Krutis

et al. 2023

JMMP

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“…A previous study (Kim et al (2019) has shown that a singlephase hybrid micro array jet impingement can attain strong impingement effects caused by reduced diameter of jet nozzles. However, the nozzle-to-surface spacing is still mainly responsible for the heat transfer efficiency for a given mass flow rate (Ahmed et al, 2021). Although this conclusion demonstrates the high performance of hybrid micro-scales with water for cooling, its compatibility with gas cooler of rotor systems remains a concern.…”

Section: Introductionmentioning

confidence: 99%

Thermal Management and Dynamic Performance of a Cooler Design for the Supercritical CO2 Turbine Shaft Cooling

Gurgenci

Guan

et al. 2022

Front. Energy Res.

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This paper presents the results of a numerical study on a supercritical CO2 (SCO2) turboshaft cooling device by considering heat transfer and hydrodynamics. A micro-cooling device with a radius clearance of 50 micron and a nozzle diameter of 4 mm was designed and used to investigate the heat transfer characteristics of a micro-spacing impinging and gas film dynamics. Sixteen nozzles (N = 16) are equally spaced around the shaft in single or double rows. Investigations include journal speed- and eccentricity-dependent forward and cross-coupled force coefficients, and the effects of nozzle layouts and mass flow rate on the heat transfer efficiency. Analysis of the correlation coefficient shows that the gas density in the radial clearance is the dominant factor affecting the convective heat transfer performance, while the fluid velocity is a secondary factor. And the cooling efficiency (mass flow utilization rate) at low cooling pressure (ps < 0.7 MPa) is significantly greater than that at high cooling pressure (ps > 0.7 MP). In addition, considering the structure alone, a dual-row cooler exhibits a higher average Nusselt number, also registers a higher mass flow rate at the same pressure. Once the shaft is heated only one end, the difference in effectiveness between single- and dual-row cooling is not significant, so coolers with a single-row configuration should be preferred. Then, experimental values for the temperature of the heated rotor are provided under specific cooling airflow conditions. Dynamic analysis results show that the force coefficient of the single-row configuration is more dependent on the journal rotation speed and eccentricity ratio, and exhibits a negative direct stiffness coefficient at higher inlet pressure and journal rotation speed. Moreover, cross-coupled terms (stiffness coefficient) generally have a more explicit variation tendency than direct terms, and are more sensitive to changes in shaft speed and eccentricity. Small clearance cooling is a relatively complex technology aimed to improve heat dissipation efficiency in gas cooling devices while minimizing the effect of hydrodynamic pressure. Comparing the gas force coefficients of different journal speeds reveals a drastic increase in the effect of hydrodynamic pressure when the journal is eccentric. The cooler may be considered for operation with compliant support (such as bump foil) to generate additional damping and appropriately compensate for the eccentricity of the rotor.

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Time-dependent heat transfer analysis of ellipsoidal protruded microchannel with multiple pulsating jets

Huang

Tan

2022

Applied Thermal Engineering

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Numerical investigation of heat transfer and flow characteristics of a double-wall cooling structure: Reverse circular jet impingement

Cited by 20 publications

References 31 publications

Experimental and Numerical Investigations into Heat Transfer Using a Jet Cooler in High-Pressure Die Casting

Experimental and Numerical Investigations into Heat Transfer Using a Jet Cooler in High-Pressure Die Casting

Thermal Management and Dynamic Performance of a Cooler Design for the Supercritical CO2 Turbine Shaft Cooling

Time-dependent heat transfer analysis of ellipsoidal protruded microchannel with multiple pulsating jets

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