Experimental Measurement of Pressure Coefficients arounnd Various Opening of Typical Wind Catchers

Wind catcher or what is called Baud – Girs in Persian language was a main component of old buildings in central region of Iran. Its function was to capture wind from external air stream and induce it into the building in order to provide natural ventilation and passive and passive cooling . it is normally a tall any direction and guiding it into the building to provide thermal comfort for occupants during the summer time. In the cold seasons, the openings were closed to isolate thee Baud-Gir and occupant regions. In this article, a 1:100 scale model of Larih’s house Baud-Gir with a cross section is employed in a laboratory wind tunnel and pressure coefficients were measured around all opening for various values of approaching air velocity and air incident angel. The experiments are also conducted when the Baud-Gir with adjoining courtyard is placed in the wake of upstream objects, resembling neighboring building . Two types of upstream objects are selected with different heights. For an isolated Baud-Gir model and for zero incident angel, it is shown that the pressure coefficients in the front or projected surface are positive and become negative downward. The same behavior is observed for other velocities. However , the pressure coefficient distributions for the back are all negative and almost uniform, indicating a large low pressure region around this face. The effect of increasing the air incident angle is to lower the pressure coefficients along the front face. For the zero incident angle, the shading effects of upstream building was to both reducing and flattening of the pressure distribution in the projects surface of the model. For thee taller upstream object, the pressure coefficients in the projected surface become uniform and negative , indicating that the model Baud-Gir is total under the wake of the upstream building and therefore in capable its duty properly.

کلیدواژه ها:

Band - Gir ، Passive coolding ' Pressure coefficient