• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.10
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• pp.773-778
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• 2015

The local heat transfer and pressure drop of developed turbulent flows in convergent/divergent channels with square axial cross-sectional areas were experimentally investigated to improve the channel design, such as a gas turbine cooling system. Square convergent/divergent channels with one ribbed wall were manufactured with a fixed rib height e of 10 mm and a ratio of rib spacing p to height e of 10. The measurement was conducted for Reynolds numbers from 15,000 to 89,000. Convergent, divergent, and straight channels with ratios $D_{ho}/D_{hi}$ of 0.75, 1.33, and 1.0, respectively, are considered. Of the three channel types, the ribbed divergent channel was found to produce the best thermal performance under identical flow rate, pumping power, and pressure loss conditions.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.14-19
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• 2011

Two difference cavitation models based on the homogeneous mixture model are used to study cavitating flows through converging-diverging channel. Here, the cloud cavities, pressure distributions and other results have been obtained and compared to evaluate two cavitation models. What's more, differences are observed in the simulated results, due to the differences in characteristics of each model. Analytical results shows that the new improvement cavitation model is validated to have better effects on simulating cavitating flows

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.65-73
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• 2005

The compressible flow of reactive fluid is investigated by using the transonic small-disturbance (TSD) model and the one-step first-order Arrhenuis chemical reaction. The fluid flow is restricted to dilute premixed reactions with small heat release. The effects of channel shape and Mach number on transonic combustion are studied by numerical analysis. The results show that the channel divergence increases the chemical reaction within the given channel length whereas the channel convergence inhibits the chemical reaction near the outlet and that increasing the inlet flow Mach number at a fixed reaction rate causes the flow acceleration in a diverging channel and the appearance of weak shock waves which do not show in the inert flow case. It also helps to increase the pressure and temperature near the diverging channel outlet and to consume the reactant within the given channel length.

• Journal of Power System Engineering
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• v.18 no.3
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• pp.66-72
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• 2014

The local heat transfer and pressure drop of developed turbulent flows in the smooth convergent/divergent channels with rectangular and square cross-sectional areas along the axial distance have been investigated experimentally. The measurement was conducted within the range of Reynolds numbers from 15,000 to 89,000. The channel hydraulic diameter ratios of 0.67 and 1.49 in the rectangular channel with 2 inclined walls and the ratios 0.75 and 1.33 in the square channel with 4 inclined walls are considered. The comparison showed that among the four channels the square divergent channel has the highest thermal performance at the identical mass flow rate, at the identical pumping power, and at the static pressure drop.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.4
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• pp.195-200
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• 2015

The thermal performance in the channels with two-wall rectangular convergent/divergent cross-sectional areas along the axial distance was investigated experimentally. The ribbed rectangular convergent/divergent channels were manufactured with a fixed rib height (e) = 10 mm and the ratio of rib spacing (p) to height (e) = 10. Three different parallel angled ribs (a = $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$) were each placed on the channel's one sided wall only. The convergent channel of $D_{ho}/D_{hi}=0.67$ and the divergent channel of $D_{ho}/D_{hi}=1.49$ were considered. The ribbed divergent channel produced better thermal performance than the ribbed convergent channel in three different restrictions; identical flow rate, identical pumping power, and identical pressure loss.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.25-32
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• 2012

This work was devoted to compare two different cavitation models to study the dependency of model constants. The cavitation model of Merkle et al.(2006) and Kunz et al.(2000) were used for the present computational study. The cavitation models were coupled with the incompressible unsteady Reynolds-Averaged Navier-Stokes solver to indicate the vaporization and condensation processes. For this purpose, a preconditioning method was added as the pseudo-time term to solve the unsteady stiffness problems. For the validation of the numerical simulation, the computation was performed for the cavitating flow in a converging-diverging channel. The present results show that Merkle's cavitation model is independent to the model constants, and the higher numerical accuracy over Kunz's cavitation model.