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Unformatted text preview: rct>^\\ C\v,\ v^i>attc"^\ ~ FLUID DYNAMICS 17"15 Pi +-f + zig + EA P 2 P2 yj p 2 El + ZL P 2gc gig 3c 223 + EE + Ef +EV + EA = 1- 1 1- Ee + rtf + a* p %gc 9c [SI] 17.65(a) [U.S.] 17.65(b) As defined, Ea, Ee, and / are all positive terms. None of the terms in Eq. 17.64 is negative. The concepts of sources and sinks can be used to decide whether the friction, pump, and turbine terms appear on the left or right side of the Bernoulli equation. An enenry__sgurce puts energy into the system. The incom ing fluid and a pump contribute energy to the system. An energy sink removes energy from the system. The leaving fluid, friction, and a turbine remove energy from the system. In an energy balance, all energy must be accounted for, and the energy sources just equal the energy sinks. /-^/sources / ^sinks 17.66 Therefore, the energy added by a pump always appears on the entrance side of the Bernoulli equation. Simi larly, the frictional energy loss always appears on the discharge side. 20. ENERGY AND HYDRAULIC GRADE LINES WITH FRICTION19 The energy grade line (EGL, also known as total energy line) is a graph of the total energy versus position in a pipeline. Since a pitot tube measures total (stagnation) energy, EGL will alwayscoincidewith the elevation of a pitotxpiezometer fluid column. When friction is present, the EGL will always slope down, in the direction of flow. Figure 17.7 illustrates the EGL for a complex pipe network. The difference between EGLfrictioniess and EGLwith friction is the energy loss due to friction.and EGLwith friction is the energy loss due to friction....
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This note was uploaded on 02/15/2012 for the course CWR 4202 taught by Professor Newman during the Fall '08 term at University of Florida.
- Fall '08