Summary
In the design stage of natural ventilation of greenhouse, wind pressure coefficient of opening is necessary. In this experiment, a model(1:12) of one type of high tunnel greenhouse with side opening, ridge opening, and with entrance/exit at gable end was installed in a boundary layer wind tunnel to determine the wind pressure coefficient at the surface and for three opening conditions. The results obtained showed that wind pressure coefficient at the surface of high tunnel changed at various wind direction, such as at wind direction angles of 0deg, 30deg, 60deg and 90deg as illustrated in Fig.4. The wind pressure coefficient of side opening, ridge opening, and entrance/exit at gable end at various wind direction as shown in Fig.5 also indicated this trend. The wind pressure coefficients across the opening were different from those at the surface when the ventilators were closed, so that the calculation of ventilationrate should be based on the values at ventilators open.Keywords: high tunnel, natural ventilation, wind pressure coefficient