EXPERIMENTAL STUDY ON VENTILATION PERFORMANCE OF A MODIFIED ROOFTOP VENTILATOR

摘要

This research experimentally investigated the ventilation characteristicsrnof a modified rooftop ventilator, and compared the results with thernconventional turbine ventilator. The modified ventilator has the combinedrnfeatures of static and turbine ventilators. A wind tunnel system is used for thisrnstudy, which simulates the condition where the wind blows over the rooftoprnventilator. The ventilation rate is determined by the air velocity at the openrnslot of a ventilation pipe connected to the inlet throat of ventilator. Thernvelocity measurements were conducted using a Laser Doppler velocimetryrn(LDV) system. The studies include ventilator rotation speeds, ventilationrncharacteristics and ventilation rates with and without ventilator’s rotation, atrndifferent wind speeds. Results show that the modified ventilator exhibitsrnbetter ventilation effects than the conventional one at low wind speeds, andrnat the conditions as the ventilator not rotating. The conventional ventilatorrnhas a negative ventilation effect when it is not in rotation, though the effect isrnsmall.