Experimental Study on the effect of permeable obstacles arrangement and bed slope on Hydraulic characteristics of Density Current

Entry of density current into dam's reservoirs leads to reduce the useful life of the dam and reduce or even eliminate the volume of water regulation and the loss of profits from flood control and power generation. One of the methods for controlling density current is the creation of barriers before the main reservoir of the dam. In this study, the effect of three bed slopes and arrangement of permeable barriers with six different types of layout on front height, forward velocity and Densitometric Froude number of high concentrations has been investigated. Experiments were performed in a channel of 10 meters in length and in three slopes of zero, one and two percent with similar convergent arrangement, similar divergent, parallel, z-shaped, Zigzags and checkered at two concentrations of 40 and 80 g / l, respectively. According to the results, the arrangement of similar convergent, checkered, similar divergent, zigzag, parallel and Z-shaped had the most effect on the hydraulic flow characteristics of the density current. The effect of different arrangement of the barriers on the hydraulic characteristics of the density current in a bed without sloping is more than the sloping bed, and also the effect of the arrangement of barriers in the critical current range is greatly reduced. The slightest effect of the obstacles on the bed without sloping is due to the similar convergent arrangement, which has reduced the Densitometric Froude number by 65%, and the effect of this arrangement on the sloping bed (the slop is 2%) has reached to 19% .The least effect of the arrangement is related to the barriers of the z-shaped arrangement. In this arrangement, the decrease in the Densitometric Froude number in the bed without sloping has been 50%, and this value with an increase in the bed slope (by 2%) has reached to 16%.