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z <br />dimensionless parameter of Q This is very convenient since Q <br />and D are known_prior to <br />i Vo <br />S D ~ ~ ~ <br />a \ <br />7Cp <br />~' •.. I <br />..: a. <br />V D' <br />g <br />the plunge pool design. <br />Water surface at maximum discharge <br /> <br />Invert of outlet channel <br />I I <br />O.iZm I 2.5 d50 <br />0.4 L„ <br />6" to 9" <br />a2 <br />Riprap filter cap <br />Figure 1 - Plunge pool definition sketch <br />DISCHARGE JET TRAJECTORY <br />The plunge pool location is determined by the discharge jet trajectory. <br />The location of the plunge pool centerline downstream from the discharge <br />end of the pige is dependent on the jet velocity and angle of impingement <br />with the pool surface as well as the plunge pool depth. <br />The jet impingement velocity and angle of entry into the pool can be <br />determined from the pipe exit slope, pipe discharge velocity, and height <br />of pipe invert above the water surface. The height of pipe Invert above <br />the water surface, Z should be measured from the tailwater elevation <br />for the associated discharge used for the plunge pool design. The <br />discharge should be the maximum prior to any secondary spillway flow. <br />The pipe slope is ~ S , where S is the sine of the angle whose <br />V1-S` <br />tangent is the slope of the pipe. The discharge velocity, Vo, is com- <br />puted based on the design discharge and the conduit cross-sectional <br />area. The path of the free falling jet is a parabola between the pipe <br />exit and tailwater surface where-the jet enters the water with the <br />impingemenC velocity, V and the slope, Can a. The horizontal <br />distance, Xp, from the pipe exit to where the jet plunges into the <br />tailwater with horizontal velocity, Vh, and vertical velocity, Vv, <br />is given in Eq. 5; where <br />(210-VI-DN-6, Second Ed., January 1986) <br />r~ a ~ GZSSGS i ~8~s= Z~pr~ ~~~ Pt9. ~ovr= ,~ ;~~ ~ <br />