Investigation of the Effect of Number of Submerged Vanes on Transverse Mixing Coefficient in a Rectangular Channel

One of the characteristics of the open channel in controlling of the pollutants are the dispersion coefficients. These coefficients are the main factor for diluting and increasing the exchange of pollutants with flow which in general reduces the mixing length. To increase the transverse coefficient and so reducing the mixing length many techniques have been applied and in this study the submerged vanes are used with variable numbers in flume widths.Tests are carried out at a glass wall rectangular channel with length 0f 15 m, 80 cm wide and 80 cm in Height in 5 different scenarios of without submerged vanes and with vanes in different number (3, 5, 7 and 9 vanes) and constant flow condition. The sodium chloride was injected in the channel center in constant discharge as tracer. The electric conductivity of the flow was measured by special instrument at four cross sections downstream of the vanes and the results are compared. The results show that generally the vanes are distribute the tracer across the section in a shorter length and the scenario with 7 vanes are more effective in which the transverse coefficient are 1.8 times with the case of no vanes.