Method of field measurement of turbulence at a bend in artificial channel

Abstract

Field measurements of turbulence was carried out at a bend in an artificial channel by electro-magnetic anemometers. Dimensions of the channel are 4.8 m in height and 5.5m in width. The velocity in the channel exceeds 1 m/s. Number of the measurement points is 83 at a section. Since the velocity is fast and the flume is large, the special cares were taken for the measurements. The frequency response of the anemometers must be quick enough for the turbulence, and the directional characteristics must be accurate. Moreover, the supporting apparatus of the anemometers should not influence the flow and should not vibrate with less than 8 Hz. The problems above are carefully examined by laboratory experiments. As the results of the field measurement the asymmetric secondary flow cell were found, probably due to the difference of the roughness.