$320$

Hydraulic Structures

Chap. $8$

$($SECTION $8\mathrm{.}10)$

$8\mathrm{.}10\mathrm{.}1.$ A horizontal rectangular stilling basin $($USBR type III$)$ is used at the outlet of a spillway to dissipate energy. The spillway discharges $350f\frac{t^3}{sec}$ and has a uniform width of $35ft.$ At the point where the water enters the basin, the velocity is $30f\frac{t}{sec}.$ Compute the following:

$($a$)$ the sequent depth of the hydraulic jump,

$($b$)$ the length of the jump,

$($c$)$ the energy loss in the jump, and

$($d$)$ the efficiency of the jump defined as the ratio of specific energy after the hydraulic jump to the specific energy before the jump.

$88\mathrm{.}10\mathrm{.}2.$ A spillway carries a discharge of $22\mathrm{.}5\frac{m^3}{sec}$ with the outlet velocity of $15\frac{m}{sec}$ at a depth of $0\mathrm{.}2m.$ Select an adequate USBR stilling basin and determine the sequent depth, the length of the hydraulic jump, and the energy loss.

$8\mathrm{.}10\mathrm{.}3.$ An increase in discharge through the spillway in Problem $8\mathrm{.}10\mathrm{.}2$ to $45\frac{m^3}{sec}$ will increase the spillway outlet depth to $0\mathrm{.}25m.$ Select an adequate USBR stilling basin and determine the sequent depth, the length, the energy loss, and the efficiency of the hydraulic jump $($defined as the ratio of specific energy after the hydraulic jump to the specific energy before the jump$).$