1 - Alaska Energy Data Inventory

1.03 HYDRAULIC LOSSES.A. General. Head losses in the power conduit are primarily caused byfrictional resistance to flow. Additional losses are caused bycontractions and expansions as flow moves into and out of rock traps~ linedsections and the gate structure. Further losses are caused by flow throughbends in the main rock trap~ the power tunnel and the penstock.In caJculating head loss~s each feature producing a hydraulic loss wasassigned a loss coefficient IIKII~ and a corresponding headloss wascalculated by the following equation:All losses were summed up, and for convenience a second form of theheadloss equation was related to the total discharge in the power conduit.This equation is:K = Loss coefficient for individual feature.hL = Head loss for individual feature (ft).V = Velocity at individual feature (ft/s).HL = Total head loss in power conduit (ft).Q = Total discharge through power conduit (ft 3 /s).K = Overall loss coefficient for entire conduit from intake to turbine.g = Acceleration due to gravity (32.2 ft/s2).The Manning formula was used to calculate friction losses in theunlined sections of tunnel while the Oarcy-Weisbach formula was used forthe 1 i ned port i on of the tunnel and the penstock. It was felt that theManning formula would be more appropriate for the irregular unlined tunnel.Bl-14