EXPERIMENTAL STUDY ON VENTILATION PERFORMANCE OF A MODIFIED ROOFTOP VENTILATOR

摘要

This research experimentally investigated the ventilation characteristics of a modified rooftop ventilator, and compared the results with the conventional turbine ventilator. The modified ventilator has the combined features of static and turbine ventilators. A wind tunnel system is used for this study, which simulates the condition where the wind blows over the rooftop ventilator. The ventilation rate is determined by the air velocity at the open slot of a ventilation pipe connected to the inlet throat of ventilator. The velocity measurements were conducted using a Laser Doppler velocimetry (LDV) system. The studies include ventilator rotation speeds, ventilation characteristics and ventilation rates with and without ventilator's rotation, at different wind speeds. Results show that the modified ventilator exhibits better ventilation effects than the conventional one at low wind speeds, and at the conditions as the ventilator not rotating. The conventional ventilator has a negative ventilation effect when it is not in rotation, though the effect is small.