Partical image velocimetry(PIV) research of airflow distribution in greenhouse under wind driven situation

The advanced flow field display technique, Particle Image Velocimetry (PIV), is applied to research the indoor and outdoor flow field of mutual inserted multi-greenhouse based on research of the common flow field visualization technique. The result of test shows there is the highest wind speed on roof and the lowest wind speed on cullis of mutual inserted multi-greenhouse in time-averaged flow when the greenhouse ventilates using shoulder and side ventilators. The wind speed of inner air flow field is small and the smallest wind speed on roof in mutual inserted multi-greenhouse. So the ventilation effect is not good and the heat congregates at housetop in the greenhouse. The instantaneous process of vortex was analyzed and the movement of circumfluence vortex was obtained in instantaneous flow field. The drag coefficient CD is 0.565 according to the vortex distribution of outer greenhouse. According to the vortex movement pictures of inner mutual inserted multi-greenhouse, it can be found that along the airflow direction, the change of vortex in arch 1 is slower than in arch 2 and 3.