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Article
Publication date: 1 January 1993

BIJAN FARHANIEH and BENGT SUNDEN

Turbulent fully developed periodic heat transfer and fluid flow characteristics in corrugated two‐dimensional ducts with constant cross‐sectional area are numerically…

61

Abstract

Turbulent fully developed periodic heat transfer and fluid flow characteristics in corrugated two‐dimensional ducts with constant cross‐sectional area are numerically investigated. The governing equations are solved numerically by a finite‐volume method for elliptic flows in complex geometries using collocated variables and Cartesian velocity components. Two different turbulence models (the second moment closure and the k—ε) for approximation of the Reynolds stresses are applied. The performance of the models were assessed by comparing the results with experimental data. The results show the advantages of the stress closure model compared to the k—ε model. The overall Nusselt number and the pressure drop ratio results are obtained for the boundary condition of a uniform wall temperature for two inclination angles ø and two duct aspect ratios (H/L) and for Reynolds number ranging from around 3000 to 35,000. The overall Nusselt number predicted by the k—ε model is upto 25% higher than the values predicted by the second moment closure. The plots of the velocity vectors show a complex flow pattern. The mechanisms of heat transfer are explained by the flow phenomena separation, deflection, recirculation, and reattachment.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 3 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 May 1992

BIJAN FARHANIEH and BENGT SUNDÉN

Laminar fully developed periodic heat transfer and fluid flow characteristics in corrugated two‐dimensional ducts with constant cross‐sectional area are numerically investigated…

158

Abstract

Laminar fully developed periodic heat transfer and fluid flow characteristics in corrugated two‐dimensional ducts with constant cross‐sectional area are numerically investigated. The governing equations are solved numerically by a finite‐volume method for elliptic flows in complex geometries using colocated variables and Cartesian velocity components. The results were obtained for a uniform wall temperature for two inclination angles and three duct aspect ratios (H/L) and for Reynolds number ranging from 30 to 1200. The plot of the velocity vectors show a complex flow pattern. Unexpected high enhancement of the average Nusselt number was observed at low Reynolds number for H/L = ½ and ⅓. A moderate increase in Nusselt number was obtained as Reynolds number was increased further.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 2 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 3 April 2018

Binghua Zhou, Yiguo Xue, Mingtian Li, Zhiqiang Li, Xueliang Zhang and Yufan Tao

When a vehicle passes through a long highway tunnel, the smoke it discharges accumulates in the tunnel. High smoke concentration has an important influence on the driver’s health…

245

Abstract

Purpose

When a vehicle passes through a long highway tunnel, the smoke it discharges accumulates in the tunnel. High smoke concentration has an important influence on the driver’s health and driving safety. The use of numerous jet fans to diffuse the smoke causes excessive energy consumption, so it is of significant practical value to design suitable tunnel ventilation.

Design/methodology/approach

The study is based on the continuum hypothesis, incompressible hypothesis, steady flow hypothesis and similar hypothesis of gas in a long highway tunnel. These hypotheses calculate the gas emissions and wind demand in a long highway tunnel given the deployment of the jet fan program.

Findings

This program selects each of the two 1120-type jet machine group and sets up 13 groups; each group has an interval of 184.5 m in the end. The analysis of air test results when the tunnel is in operation shows that CO and smoke concentrations meet the design requirements, which can provide reference for a similar engineering design later.

Originality/value

At present, a highway tunnel is recognized at home and abroad by means of clearance of longitudinal ventilation, which is 2,000 m. In view of this, this paper is based on the theory of longitudinal jet ventilation of a highway tunnel, whose length is more than 2,000 m, to calculate the ventilation and apply it to a tunnel’s ventilation design.

Details

Journal of Engineering, Design and Technology, vol. 16 no. 2
Type: Research Article
ISSN: 1726-0531

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