Hydraulics Section II:Hydraulics Section II:Hydraulic EnergyHydraulic Energy

Paul Trotta, P.E., Ph.D.Paul Trotta, P.E., Ph.D.Justin Ramsey, P.E.Justin Ramsey, P.E.

Chad Cooper Chad Cooper

University Curriculum Development University Curriculum Development for Decentralized Wastewater for Decentralized Wastewater

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CitationCitation

Trotta, P.D., and J.O. Ramsey. 2005. Hydraulics II: Trotta, P.D., and J.O. Ramsey. 2005. Hydraulics II: Energy Energy -- PowerPoint Presentation. PowerPoint Presentation. inin (M.A. (M.A. Gross and N.E. Deal, eds.) University Gross and N.E. Deal, eds.) University Curriculum Development for Decentralized Curriculum Development for Decentralized Wastewater Management. National Wastewater Management. National Decentralized Water Resources Capacity Decentralized Water Resources Capacity Development Project. University of Arkansas, Development Project. University of Arkansas, Fayetteville, AR.Fayetteville, AR.

Section Objectives:Section Objectives:Understand the three forms of Hydraulic Understand the three forms of Hydraulic Energy: Elevation Head, Pressure Head, Energy: Elevation Head, Pressure Head, and Velocity Headand Velocity HeadLearn the Laws of Conservation of Learn the Laws of Conservation of Hydraulic Energy and corresponding Hydraulic Energy and corresponding equationsequationsCompute Orifice Flow and Friction LossesCompute Orifice Flow and Friction LossesUnderstand effects of Water HammerUnderstand effects of Water Hammer

Pressure HeadPressure HeadPressure head adds to the total energy of a unit Pressure head adds to the total energy of a unit

volume of water at an arbitrary elevation volume of water at an arbitrary elevation ““zz””

Elevation HeadElevation HeadCarry a bucket of water up a flight of stairs and the work Carry a bucket of water up a flight of stairs and the work

you have done in part goes into potential energy of the you have done in part goes into potential energy of the water.water.

Elevation Head or Static LiftElevation Head or Static LiftElevation Head is also known as Elevation Head is also known as ‘‘Static LiftStatic Lift’’

Velocity HeadVelocity HeadThe Velocity Head of water is similar to the rise and The Velocity Head of water is similar to the rise and

fall of water balloons launched into the air.fall of water balloons launched into the air.

Conservation of EnergyConservation of Energy

P1/density + V12/2g + Z1 + Energy Added (pump head) = Initial Hydraulic Energy

P2/density + V22/2g + Z2 + Head LossesFinal Hydraulic Energy

Pressure Head @1 + Velocity Head @1 + Elevation Head @ 1 + Pump Head Added

Equals

Pressure Head @2 + Velocity Head @2 + Elevation Head @ 2 + Friction Losses

Energy Between PointsEnergy Between PointsThe Energy at each point in this systemThe Energy at each point in this system must be must be appropriately calculated and accounted for.appropriately calculated and accounted for.

Orifice FlowOrifice Flow

Qorifice = C * Dorifice2* Z 1/2

Where C = k * Π /4 * (2g) 1/2

Water HammerWater Hammer

Rapidly closing or opening a valve causes pressure transients in pipelines, known as water hammer.

Energy Grade Line Surge Line