• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.982-992
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• 2001

In this paper, the performance of ventilation equipments in enclosed parking garages were investigated for several air distribution systems by numerical method. Air change effectiveness of the non-mixing system was 0.42. It meant that more supply air as much as the design supply air was needed to maintain good indoor air quality. In the high speed nozzle ventilating system which is most expensive one, air change effectiveness was 0.54. Therefore this system satisfied to ventilation design. In the jet fan ventilating systems, air change effectiveness for jet fan ventilating system-A with 18 jet fans and jet fan ventilating system-B with 6 jet fans in circulation mixing arrangement were 0.565 and 0.42 respectively. Jet fan ventilating system-C with 6 jet fans in transport mixing arrangement was 0.535. Jet fan ventilating system-A and jet fan ventilating system-C met the ventilation design. But velocity in jet fan ventilating system-A was over 2.0m/s which is inappropriate in human comfort. Therefore this system is not proper to ventilation. Jet fan ventilating system-C was the optimum one for enclosed parking garages among 5 systems examined in this paper.

• The KSFM Journal of Fluid Machinery
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• v.14 no.4
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• pp.25-30
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• 2011

The jet fan is generally used to add thrust in the longitudinal ventilation system of road tunnel and the geometric conditions of jet fan such as the distance from tunnel wall have an effect on the performance of ventilation system. Numerical analyses on the flow in tunnel caused by operation of jet fan are presented to study the ventilation characteristics in tunnel. While the distance between jet fans in parallel installed in tunnel is changed 0.5 L/D to 3.0 L/D, the flowrate and mean velocity through tunnel are calculated for each cases. As the distance between jet fans increases, the flowrate through tunnel increases asymptotically and the momentum of tunnel flow is alike.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2765-2770
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• 2008

The purpose of tunnel ventilation system for long road tunnels is to keep certain levels of Visibility Index and the concentration of CO. Additional equipments such as jet fans are used in road tunnel to discharge pollutants in the road tunnel. The control algorism of tunnel ventilation system takes the value of sensors as input, and then gives the operation method of jet fans in tunnel as output. Information on the variation of CO concentration in tunnel when jet fans are running is needed to minimize their operation time. Numerical analysis is used in this paper because of the difficulty of conducting experiments under standard condition for ventilation of road tunnel. The concentration of CO has been calculated by using 3-dimensional CFD under transient condition with speed of cars, quantity of air ventilation, and the results for various operation position of jet fans are compared.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.10-13
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• 2010

The flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, jet fan is one of main ventilation facilities especially in longitudinal ventilation system of tunnel. In this study to analyze tunnel flow induced by operation of jet fan, numerical simulation has been carried out. The velocity distributions and streamlines in tunnel are examined to consider the three-dimensional characteristics of tunnel flow caused by jet fan.

• Journal of computational fluids engineering
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• v.11 no.4 s.35
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• pp.20-25
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• 2006

In the present study, flow characteristics inside a road tunnel are simulated for the ventilation flows due to jet fan system and flows induces by the traffic. Traffic ventilation is numerically simulated by multiple reference frame. From the results of steady state simulation of tunnel ventilation, it is found that the proper ventilation is achieved by the designed jet fan system along with ventilating flow induced by the traffic. A transient simulation is also performed for the case of vehicle fire in the tunnel reversing the direction of rotation of some fans. The results suggest that the heat and smoke can be controlled by the proper changing of fan operation mode. The present results can be used to design proper ventilation system and effective smoke control system as well.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.8
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• pp.763-770
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• 2000

In tunnel ventilation, the Purpose of ventilation control is to keep the required pollution level with minimum consumption of energy But tunnel ventilation has large disturbances caused by discharge of pollutants, traffic forces especially strong for longitudinal ventilation. Hence in this paper, the tunnel ventilation control logic applying fuzzy control theories is proposed and the simulation program of tunnel ventilation control is developed. The characteristics of longitudinal ventilation with jet fans are estimated and the effect of the proposed tunnel ventilation control is verified by the simulation program.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.2
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• pp.103-109
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• 1994

An experimental study is performed on the flow characteristics of a swirl-jet diffuser for factory ventilation. Swirl number ranges from 0(nonswirl jet) to 0.6 when the angle of swirl vane is 60 degree. As swirl becomes strong, the maximum velocity in the plane perpendicular to jet axis decreases fast and the uniformity of velocity becomes good, particularly in the ventilated area. The similarity in velocity profiles has been found for axial velocity from even when swirl number equals 0.6. The flow characteristics of the swirl-jet which has the swirl number of 0.6 is thought to be the best among these three swirl numbers for factory ventilation. However, the pressure drop in the diffuser increases as the swirl becomes strong. This should be considered in the design of the total ventilation system including a duct system.

• Plant Journal
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• v.4 no.2
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• pp.66-72
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• 2008

In this inquiry, I would suggest jet ventilation system for effective elimination of welding flaw at machinery material welding shop on plant and evaluate the airstream on inner space and property of welding flaw's density through the examination. We can know outer atmosphere inflows at the speed of about 0.05m/s from western entrance in case of stopping the jet ventilation system, but airstream is accumulated on entire space. At height of worker's breathing surface(Ground Level = 1.5 m, below of GL) and welding work center, density of welding flaw on upper part(GL = 12m) is appeared 4 times higher than outer atmosphere at surplus range besides nearby of western entrance. At operation of jet ventilation system, since the smooth air current transfer at inner space and exhaust effect the wind speed is maintained at 0.932 m/s at the point of height of worker's breathing surface on inner space and it's concluded about the working conditions have been better than before operation of jet ventilation system because of that results show that inner space density of welding flaw at height of worker's breathing surface is 40.5%, and in the work shop, it is 20.3% at upper part.

• Tunnel and Underground Space
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• v.13 no.3
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• pp.235-243
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• 2003

Recent worldwide trends show that tunnel length is getting longer, and the demand for longitudinal ventilation system with jet-fans in highway tunnels has also increased mainly due to the economic reasons. Improvements in vehicle engine subsequently reduced required ventilation rate(Qreq) which is the decisive factor in choosing the optimal ventilation system. Qreq contour map is a graph that defines the relationship among tunnel length, grade and required ventilation rate. It is important to understand the variation of Qreq in order to evaluate the characteristics of ventilation system with jet fans. Therefore this study aims at studying a graphical method for determining the characteristics of jet-fm ventilation system using Qreq contour map. Also, this study focuses on traffic composition on local highways.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.71-74
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• 2008

This paper aims at studying the key design elements for the optimal ventilation system design, developing the design models and suggesting the design guidelines. The key elements include the basic exhaust emission rate, wall friction coefficient, vehicle drag coefficient and slip streaming effect, jet fan operating efficiency, natural ventilation force and installation scheme for jet fans and ventilation monitors in tunnel. The design models developed in this study are one-dimensional ventilation simulator to analyze the air flow, pressure profile and pollutant dispersion inside and outside tunnel, expert model to choose the optimal ventilation method, and the ventilation characteristic chart to evaluate the preliminary ventilation system. The study results are reflected in the design guideline for road tunnel ventilation system.