Longitudinal ventilation systems are commonly installed in new tunnels in big cities of the Far Eastincluding Mainland China, Hong Kong and Taiwan. Many tunnels are found and some of them areinclined at an angle to the horizontal. However, smoke movement in those tilted tunnels is not fullyunderstood. Some longitudinal ventilation was designed based on presumed smoke movementpattern without experimental demonstration.Smoke movement pattern in a tilted tunnel model was studied by scale modeling technique.
In dwellings ventilated by extract ventilation there are common complaints of cold draught caused by the supply air entering the room through openings close to the windows. This paper reports on studies of unconventional ways to distribute the supply air in order to minimise the risk of such problems. Experiments have been done where the supply air device is located in the hall of an apartment. The ventilation efficiency in the rooms adjacent to the hall has been studied with open and closed doors. The behaviour of gravity currents has also been studied in scale models.
A large-scale model of an attic construction has been built in a climatic chamber. The purpose of the attic test model is to investigate hear transfer-in particular, heat transfer by convection-in loose-fill attic insulation. The influence of a number of factors on heat flows can be investigated using the attic test model; for example, insulation thickness, attic ventilation, ceiling construction, roof slopes, and the quality of installation workmanship. The heat flow through the attic ceiling construction is measured with a metering box.
Effective ventilation systems for a factory where various kinds of contaminant are discharged from many point sources are investigated in this study. Two ventilation systems are examined by scale model experiment using tracer gas. One system supplies fresh air and exhausts indoor air through the ceiling; the other has the inlet in the floor and outlet in the ceiling. Each system has a hanging wall installed at the ceiling, a device for immediate removal of the contaminant before it diffuses into the whole space.
Improvement in methods of air flow pattern scale modelling in large enclosure requires above all, précising the conditions necessary in the model in order to maintain Reynolds number independence of the mean flow, as well as defining ways in which the flow turbulent structure could be simulated. The paper presents the results of experimental analyses of air velocity fields in scale models in the range of Reynolds number 1850 to 98000. The field maps of air velocity mean value were tested.
Login