A numerical study of compressible viscous flow in a novel exhaust system

1991 ◽  
Author(s):  
MADHAVAN NARAYANAN ◽  
SUSAN YING ◽  
CHOUDARY BOBBA ◽  
JAMES YOUNGHANS
2012 ◽  
Vol 256-259 ◽  
pp. 2803-2812 ◽  
Author(s):  
Hua Yang ◽  
Richard Yuen ◽  
He Ping Zhang

Smoke control for the underground platform of a high-speed railway station was investigated. Nowadays, the development of high-speed railway in China is rapid. In order to economize valuable urban space and to realize the convenient interchange to the subway, some of the high-speed railway station platforms and transfer halls are set underground. It is difficult and uneconomic to achieve static ventilation in the underground platform. Therefore, The mechanical smoke control system is the most feasible and most reliable method to ensure the fire safety of the underground platform. How to protect the evacuation stairs free from the threat of fire-induced smoke is a major concern of smoke control in the underground platform. An underground island platform and underground waiting and transfer halls of an under construct high-speed railway station in south China are reconstructed in this paper. Three smoke control modes based on mechanical ventilation, namely mechanical air makeup, pressurized air supply for stairwell and air curtain, are numerically simulated by Computational Fluid Dynamics (CFD) method. The distribution of smoke, temperature, and CO in the platform and influences of them on evacuation staircases are computed and analyzed. The effect of fire location in smoke spread are explored in our research. This study based on CFD modeling enables the improvement of the design and operation of smoke control and exhaust system for underground high-speed railway station. The results are applicable to practical fire engineering designs for underground high-speed railway station platform.


2013 ◽  
Vol 312 ◽  
pp. 235-238
Author(s):  
Ji Gao ◽  
Rui Shan Yuan ◽  
Ming Hui Zhang ◽  
Yong Hui Xie

In this paper, the effects of angle of attack, camber and camber location on propulsion performance of flapping airfoils undergoing plunging motion were numerically studied at Re=20000 and h=0.175. The unsteady incompressible viscous flow around four different airfoil sections was simulated applying the dynamic mesh. The results show that the time averaged thrust coefficient CTmean and propulsive efficiency η of the symmetric airfoil decrease with the increasing angle of attack, and the variation of CTmean is more obvious than that of CPmean. Both CTmean and η for NACA airfoils studied in this paper decrease with the increasing camber and the difference between the propulsion performances of different airfoils is not obvious, and the thrust generation and power of various NACA airfoils gradually increase during the downstroke and decrease during the upstroke. Under the same conditions, the airfoil with a further distance between the maximum camber location and the chord of the leading edge leads to higher propulsive efficiency.


2003 ◽  
Vol 7 (3) ◽  
pp. 234-240
Author(s):  
Li-Bing Wang ◽  
Yu-Lu Liu ◽  
Min-Jie Tu

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