A Wind Tunnel Experimental Analysis of the Ventilation Characteristics of a Room with Single-Sided Opening in Uniform Flow

Abstract

Wind-induced cross ventilation is one of the key technologies for saving energy while controlling the indoor environment, and seems to be a crucial element of any sustainable building policy. However, it is sometimes difficult to arrange openings on two sides for cross ventilation of a room. In buildings in built-up areas, many rooms only have openings on a single side. Since the airflow rate for a single-sided opening is much lower than that for two-sided openings, it is important to study how we can increase the airflow rate for a singlesided opening using either passive or active techniques. In this study, the characteristics of wind-induced ventilation with single-sided openings were analysed through wind tunnel experiments. In some experimental cases, a small object was attached to the opening in order to increase the airflow rate. (It was assumed that this object replicated a pivoted window whose vertical axis was in the centre of the window.) In other experimental cases, circulation flow was artificially induced in the room used in the experimental model in order to increase the airflow rate. A synergistic effect from the fresh air entering through the opening was expected with the circulation.

Impact of aperture separation on wind-driven single-sided natural ventilation

“…Analysis of the flows observed in these (and earlier [5]  67.5º: for this angle the external flow is attached to the building façade and the ventilation is driven by shear (similar to single opening flows [10]).…”

“…The SS1 case has been much studied [8,9,10,11] and explained in terms of unsteady static pressure variations across the opening, a growing shear layer generated by the flow along the building façade, or a combination of both. Recently, Ai and Mak [12] measured instantaneous flow rates in a single-room small building in a boundary layer wind tunnel and concluded that the fluctuating part of the flow contributed between 15 and 64% to the ventilation rate (depending on wind direction).…”

Measurements and modeling of airing through porches of a historical church

“…Moreover, in case when wind is parallel to the openings, the flow rate is almost the same as the no wind cases both in singlesided and cross-flows. However, different studies has pointed out to airing flow rates even in case when the wind is parallel to the opening (Kato et al 2006;Yamanaka et al 2006), bearing in mind that the buoyancy effect can both increase or decrease the total flow rates in combination with the wind effect.…”

A wind tunnel study of wind-driven airing through open doors

“…The sample of air was taken with a perforated vertical tube provided with 12 holes at different heights; see Figure 1. The decay method is widely used in field and model studies (Etheridge & Sandberg, 1996;Hayati et al, 2017;Kato et al, 2006;Larsen & Heiselberg, 2008;Mattsson et al 2011;Warren & Parkins, 1977;Yamanaka et al, 2006). A small electric fan was used inside the model in order to mix the air inside the interior volume and create a uniform concentration of the tracer gas.…”

“…The value of C = 0.025 is used in the empirical British standard model, BS 5925, for single-sided flow through one window (British Standards Institution, 1991). Kato, Kono, Hasama, Ooka, and Takahashi (2006) investigated the single-sided ventilation by model studies in a wind tunnel using tracer gas. They found that the flow coefficient was C = 0.015 for the case of one square window, located in the middle of the facade parallel to the wind, and where the porosity of the opening was 6.25% (opening area divided by façade area), but C = 0.020 with a larger opening, yielding a porosity of 12.25%.…”