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z <br />dimensionless parameter of ~ This is very convenient since Q <br />v gD' <br />and D are known_prior to the plunge pool design. <br />Water surface at maximum discharge <br />\\ ~ <br />Zp I a \ ~ Invert of outlet channel- <br />I I <br />O.gZm I 2.5 d50 <br />0~ <br />LT,~\ al }a2 <br />6" to 9" <br />Riprap filter eap <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 pipe 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 Che 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, Zp, should be measured Erom 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 Che 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 [he pipe <br />exit and tailwater surface where the jet enters the water with the <br />impingement velocity, Vp, and the slope, tan a. The horizontal <br />distance, Xp, from the pipe exit [o 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 />Y J ~ ~~Js~~ ~ ~S~ ~ ~C-I~1~~ ~1/l~~ ~~~~/~` f"d0i ~1 ~yW I X~vV~ O <br />