CEIE 230 H-C Approach

CEIE 230 H-C Approach - Hazen-Williams (another method for...

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Hazen-Williams Approach (for determining headloss due to friction of the pipe) V = 1.318 C R 0.63 S 0.54 (EGS) V = 0.8492 C R 0.63 S 0.54 (SI) H-W Coefficient (C) -- based only on pipe roughness -- provided by pipe manufacturer Hydraulic Radius (R) -- R = A / P w = D/4 (for round pipe) Energy Gradient (S) -- S = h L / L Hazen-Williams (another method for calculating headloss due to friction) Continuity (at a node or system overall) 2. Headloss (Darcy or H-W) 3. Flow direction -- (highest total energy --> lowest) 4. Energy Gradient -- S = [ V / 1.318 C R 0.63 ] 1.85 (EGS) Q 1 Q 2 Q 3 Q 2 = Q 1 + Q 3 Q 3 Q 2 Q 1 Q 1 = Q 2 + Q 3 Pipe Networks Continuity (at a node or system overall) 2. Headloss (Darcy or H-W) 3. Flow direction -- (highest total energy --> lowest) 4. Energy Gradient -- S = [ V / 1.318 C R 0.63 ] 1.85 (EGS) 5. Loop Headlosses -- algebraic sum of headlosses around a closed loop = zero -- h L depends on velocity of fluid in pipe -- need to adjust velocity until ! h L(loop) = zero 6. Flow Rate Adjustment " Q = [ - ! (h L(loop) ] / [n ! (h L(each pipe) / Q) ] Pipe Networks
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Steps in Hardy Cross Pipe Network Solution 1. Assign an “assumed” flow rate (Q) to each pipe in the network. 2. Balance flows at each node for continuity. 3. Define a sign convention for the direction of flow in each pipe – e.g. : ! Positive (+) if flowing “clockwise” around the loop ! Negative (-) if flowing “counterclockwise” around the loop 4. Assign a flow direction sign to each pipe’s flow rate based on the defined sign convention. 5.
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This note was uploaded on 11/11/2009 for the course CEIE 230 taught by Professor Binnning during the Spring '09 term at George Mason.

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CEIE 230 H-C Approach - Hazen-Williams (another method for...

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