2.2 Wind velocity measurement
The wind measurement system is composed of ”L” type pitot tube,
micromanometer, hose and bracket. The pitot tube is fixed at a height of
70 cm above the central axis of the wind tunnel bottom plate, 2 m from
the upwind edge of the sample trough. The micromanometer is connected
with the pitot tube through a hose. During the experiment, the pressure
difference between the full pressure end and the static pressure end of
the pitot tube was showed by the micromanometer, and then, combining
with the real-time temperature and pressure, the wind velocity was
calculated. The experimental wind velocity, i.e. 70 cm high axis wind
velocity are 8, 10, 12, 14 and 16 m·s-1 respectively,
and the corresponding friction wind velocity (u *)
are 0.34, 0.42, 0.51, 0.59 and 0.68 m·s-1respectively.