Wind Pressure Fluctuation on the Roof of a Rigid Model Greenhouse using a Wind Tunnel

Studies on the windproof characteristics of a greenhouse (I)

Abstract

At present, there are many greenhouses for cultivation of many kinds of vegetables. Generally, they are very lightweight and, therefore, it is easy to be destroyed by aerodynamic forces. However, studies on the windproof characteristics of greenhouse is less than that of the general architecture of buildings. So, this paper discusses the pressure fluctuations on the roof of several rigid model greenhouses using a wind tunnel, in which experiments are carried out in two cases of model shape. One is a gabled roof and the other is round shaped. Wind speeds used are 10-20m/s. Measurements of wind pressure are carried out at 10 points a model roof. Wind pressure coefficients and power spectral densities are calculated from time series data obtained.
Results obtained are as follows: Excellent oscillations appear on the roof of the upstream side of gabled and round-shaped model. These excellent oscillations are due to vortex production in the turbulent boundary layer near the roof. In the case of gabled model except for gently inclined roofs, excellent oscillations were not observed, but were observed in the case of a round-shaped model. So, a round-shaped greenhouse is more influenced regarding vibration by the wake than the case of gabled houses.