alaa elhazek - Academia.edu (original) (raw)

alaa elhazek

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Fayoum University Journal of Engineering

Alexandria Engineering Journal, 2021

Prediction of scour depths is an important aspect related to the overall stability of hydraulic s... more Prediction of scour depths is an important aspect related to the overall stability of hydraulic structures. In this research, small-scale laboratory experiments were carried out to explore the effectiveness of mixing different percentages of Nanomaterial (Silica fume) to non-cohesive (alluvial) movable bed soil to develop mixture of bed material with significant characteristics to minimize the local scour caused by high-velocity jets downstream of a sluice gate. The experiments were executed employing 9 jet Froude numbers ranged from 1.88 to 2.81 associated with 3 heights for gate opening, and 3 tailwater depths. The bed material has 5 different percentages of Silica fume mixed by weight and 2 types of mixing with and without water were used. Ninety-nine experiments were conducted, out of which 9 experiments were done using fine sand as a bed material for the referenced cases. Graphical relationships were presented for maximum scouring and silting depths for different hydraulic conditions and bed materials. This research demonstrated that the type of mix (dry-mix or wet-mix) had a significant influence on the geometry of scouring and silting for the same flow conditions and the mixed percentage ratio of Silica fume. For dry-mix, the scouring and silting depths increased as the percentage ratio of Silica fume increased. While for wet-mix, the scouring and silting depths decreased as the percentage ratio of Silica fume increased. Also, the wet-mix effectively reduced the local scour volumes by 34.65% and 83.05% and decreased the silting volumes by 33.35% and 89.42% according to the percentage of Silica fume. Using a bed mixture of 8% Silica fume wet-mix showed 83.05% and 89.42% decrease in scouring and silting volumes, respectively, compared to pure fine sand bed material. From practical and financial aspects, the presented composition of bed material can effectively replace the smooth apron or at least decrease its length to reduce the construction cost. The obtained results present an untraditional technique for local scour protection downstream hydraulic structures.

Journal of Scientific Research and Reports, 2018

In this paper, a simple irrigation pipeline system is proposed to represent the common situation ... more In this paper, a simple irrigation pipeline system is proposed to represent the common situation of lifting water from a reservoir to another higher reservoir through a pipeline. Bentley HAMMER model is used to perform simulation and analysis of steady state and transients in the irrigation pipeline system. To protect the irrigation pipeline system against positive and negative hydraulic transient pressures due to power failure, a hydro pneumatic tank is employed. The diameter, liquid and tank volumes are studied versus max pressure and vapor volume affecting the irrigation pipeline system. It is concluded that decreasing the diameter till 1/6 times the pipeline diameter, the max pressure decreases. More decreasing the diameter, the max pressure increases. Decreasing the diameter till 1/4 times the pipeline diameter, no vapor is formed. More decreasing the diameter, the vapor exists. As the liquid volume decreases; the max pressure increase for each value of the diameter, while the vapor increases for the diameters less than or equal 1/6 times the pipeline diameter. The time after which check valve of pump closes varies according to the diameter and liquid volume. Design chart and nine design equations are obtained to get easy and effective design for hydro pneumatic tank. Employing the deduced design chart or the obtained design equations accomplish savings 55% in the diameter and 51% in liquid and tank volumes for the hydro pneumatic tank.

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