Paper 2
A Numerical and Experimental
Evaluation of a Natural Wind Driven Suction Cylinder for Building
Ventilation
J. Guha and S. Holmberg
Fluid and Climate Technology, School of Technology and
Health, Royal Institute of Technology, KTH Marinens väg 30, SE-13640
Haninge, Stockholm, Sweden
Abstract
The suction cylinder described in this paper is a device to increase
the ventilation flow rate, especially in naturally ventilated buildings.
Outdoor wind is the driving force. The principle of operation is the
development of a pressure drop created by the relative increase in flow
velocity as wind driven air flows through a nozzle. This paper basically
describes how this pressure drop and resultant momentum can be used to
provide exhaust ventilation. The suction cylinder is particularly designed
for natural and hybrid ventilation systems, especially for times when the
temperature gradient between inside and outside is not enough to drive
stack driven ventilation. A 1-dimensional analytical flow model was
derived to establish a relationship between the volume of air entering
through the inlet and the volume of air sucked by the suction cylinder.
The commercial Computational Fluid Dynamics (CFD) code, Fluent, was used
to visualise the flow system inside the suction cylinder. A corresponding
wind tunnel experiment was also made. Preliminary results show advantages
in using a suction cylinder for building ventilation.
Key words: CFD modelling for ventilation, ejector principle,
forcing natural ventilation resources, hybrid ventilation, natural
ventilation, flue gas backdraught.
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