The airflow rate of a building ventilated by wind is usually predicted by using the wind pressure coefficients obtained for a sealed building and discharge coefficients based on measuring the airflow characteristics through an opening in a sealed chamber (chamber method). This can result in the underestimation of wind driven flow through large openings located on opposite sides of a room. In this paper, the discharge coefficient, based on the chamber method, and the actual condition of cross-ventilation are calculated and compared with each other by means of stream tube analysis.
This paper attempts to look at the unsteady flow pressure on the blade tip in order to quantify the inception of instability of an axial-flow ventilation fan. A test rig was set up to measure the unsteady static pressure near the rotor blade tip region by mounting several transducers on the outer casing. The data sampling system was configured for acquisition and post analysis. The measurement results showed that, as the throttle was closed, the flow disturbance appeared firstly at the rotor inlet.
Effective planning of building ventilation, whether passive or mechanically assisted, requires detailed information about external air temperature. This paper presents experimental evidence from Adelaide, Australia, that demonstrates substantial intra-urban variations in air temperature, whose magnitude changes across the urban space and as a function of time.
Natural ventilation, as a medium for air exchange between the indoor and outdoor environment, is known for its functions of providing outdoor ‘fresh’ air and removing indoor air pollutants. In this study, the minimum outdoor air ventilation rate required to maintain radon concentration at an acceptable level was determined.
The advantage of conventional personalized ventilation (PV) is to considerably improve the fresh air percentage near PV air terminal devices (ATDs). However, the distribution of the fresh air percentage is very uneven in the field. Occupants are confined to their working zones in order to obtain good inhaled air quality. Ceiling mounted PV can overcome the disadvantages of conventional PV, although the fresh air percentage is lower than that of conventional PV near working zones.
Numerical simulations and computational fluid dynamics can be usefully integrated with architecturalmodelling to provide designers with a powerful single CFD based architectural modelling and designframework. This framework can be interfaced with building thermal performance modelling thus further integrating the full thermal and flow domains within architectural modelling. CFD analysis is generally restricted to the buildings environment flows or indoor single rooms and flow in spaces.
The UK Building Regulations regarding the provision of openings to promote natural ventilation of dwellings were modified in 2006 and, with the increased demand for sealing of structures to prevent the ingress of unwanted air, there is the possibility that under certain design conditions there would be insufficient provision of outside air in the absence of window opening or mechanical ventilation.
Even if there is only one opening within a room and there is no temperature difference between the inside outside, the room will be ventilated by the external natural wind. Two kinds of theoretical approach have tried before to evaluate the mechanisms driving this flow: one is pulsation theory and the other is mixing layer theory. In this paper, these theories are reviewed and the validity of each is examined by means wind tunnel test. Results showed that the pulsation theory was not applicable to all wind directions.
The objective of this study is to investigate how measured ventilation rates in dwellings vary over the heating season in a Nordic climate. The aim is to draw conclusions about the possibility to transform a measurement result obtained during a relatively short period of time into one which would have been expected as an average over a whole season. If such normalisation of measurement data is not possible, dwellings may be misclassified as under- or over-ventilated, a matter which may dilute a possible relationship between health and air quality in epidemiological studies.
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