Lee-side ventilation-induced air movement in a large-scale multi-span greenhouse

Lee-side ventilation-induced air movement was experimentally investigated i n a 1728 m(2) multi-span glasshouse. Air velocity measurements were perform ed by means of a customized multi-point two-dimensional sonic anemometer sy stem which simultaneously measured the horizontal air velocity components p arallel and normal to the ridge at 3 Hz frequency. The airflow pattern in t he horizontal plane of a greenhouse was analysed qualitatively under differ ent external wind conditions. The experimental results show both the vertic al and the horizontal profiles of the normalized interior air speed as a fu nction of the measurement height, the external wind speed and opening angle were acceptably presented by the simple linear functions. The airflow in t he horizontal plane was of low turbulence with large eddies. (C) 1999 Silso e Research Institute.