1 - Alaska Energy Data Inventory

3.03 HYDRAULIC LOSSES.A. General. Head losses in the power conduit are primarily caused bythe frictional resistance to flow. Additional losses result from trashrackinterferences, entrance contractions, bends within the conduit, rock traps,contractions and expansions as flow moves from 1 ined to unl ined sections,and the gate structure. In calculating head losses each feature producinga hydraulic loss was assigned a loss coefficient "k". A total hydraulicloss was arrived at with the equation:H = KV 2L -2gA second form of the headloss equation was related to total discharge inthe power conduit. The equation is:H = K Q2L -v = Velocity in concrete lined section of power tunnel.k = Sum of individual loss coefficients.Q = Total discharge through power conduit.(ft3/s)HL = Head loss in section of tunnel under consideration.K = Head loss coefficient in the entire power conduit.g = Acceleration of gravity.(32.2 ft/s2)(ft/s)The Manning formula was used to calculate friction losses in theunlined tunnel while the Darcy Weisbach formula was used in the linedportion of tunnel and in the penstock. It was felt that because of thegeneral irregularity of an unlined tunnel the Manning formula would be moreappropriate in that portion.(ft)(ft)83-4