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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Lesson 2 <br /> <br />B. Energy Equation <br /> <br />Basic Hydraulics - Participant Workbook <br /> <br />ENERGY EQUATION <br /> <br /> <br />V2 V2 <br />Z,+y,+-L=Z2+Y2+-L + hL <br />2g 2g <br /> <br />2.4 Energy Equation 2.5 Energy Equation Diagram <br /> <br />V2 V2 <br />1 2 h <br />Z,+Y,+-=Z2+Y2+- + L <br />2g 2g <br /> <br />where: z1 and z2 = <br /> Y1 and Y2 = <br /> V1 and V2 = <br /> hL = <br /> g = <br /> <br />2-2a <br /> <br />elevations of the streambed at the upstream and <br />downstream sections respectively (ft) <br />depths of flow at the upstream and downstream <br />sections respectively (ft) <br />average velocity of flow at the upstream and <br />downstream sections respectively (ft/sec) <br />head losses between sections 1 and 2 <br /> <br />the acceleration due to gravity 32.2 ft/sec2 <br /> <br />The energy grade line (EGL) represents the total energy at any given section, defined <br />as the sum of the three components of energy represented on each side of the energy <br />equation. These components of energy are often referred to as the: <br /> <br />1. Velocity head <br />2. Pressure head <br />3. Elevation head <br /> <br />The hydraulic gradeline (HGL) is below the EGL by the amount of the velocity head, or <br />is the sum of just the pressure head and elevation head. <br /> <br />The specific energy is the energy relative the to channel bed (no elevation head). <br /> <br />2-5 <br />