wind tunnel test

The ventilative cooling by natural ventilation is important technology for the buildings in urban area for the sake of energy saving and BCP (Business Continuity Plan). In fact, a large number of high-rise buildings in urban area in Japanese metropolises are equipped with natural ventilation apparatus such as openings and chimneys or shafts.

In predicting flow rate of a building ventilated by wind, the orifice equation is usually used. This conventional method cannot work for the building provided with large openings. Therefore, the final goal of this study is to establish a new prediction method of the cross-ventilation rate, which is based on energy balance inside the stream tubes passing through/around a building. In determining stream tubes, it is beneficial to use CFD. In this study, the accuracy of CFD analysis is studied. Three turbulence models are used in the simulation; i.e.

Cross-ventilation is regarded to be beneficial control method to obtain thermal comfort in a hot summer without using mechanical devices. Since it is complicated flow phenomenon, details of flow characteristics have not been sufficiently known. The final goal of this work is to establish a new prediction method of flow rate based on energy balance within the stream tube passing through or around the building. To validate numerical results obtained by CFD, they need to be compared with experimental results.

The calculation system for vertical ventilation with wind chimney on the roof driven by wind and buoyancy is presented and the necessary data is measured. The calculation system is based on the “pressure – airflow rate relationship (Pressure -Volume curve: P-V curve)” and the local velocity and static pressure at the point of chimney top. The P-V curves were measured by wind tunnel test for some typical shapes of wind chimney top. It is turned out that the effect of upper wind velocity can be eliminated by normalization of the pressure at chimney neck and airflow rate through the chimney.

The light well is often designed in the center of high-rise apartment buildings in Japan. This light well is an empty space without ceilings or floors from the bottom to the top, and this well is called "Void" in Japan. In this well, the exhaust from the kitchen and the gas water heater is sometimes discharged to the corridors surrounding Void, and the exhaust can pollute the air in Void. To keep the air quality in Void clean, the natural ventilation is usually depended on.

A wind tunnel study was carried out to investigate the airflow through courtyard and atrium building models. Ventilation strategies resulting from the use of different atrium roof pressure regimes (positive pressure and suction) were examined and compared with the performance of the open courtyard. The model buildings were monitored both in isolation and in idealised urban environments of varying group layout densities. The effect of wind direction was also observed.