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<br />ft <br />I <br />o <br />o <br />o <br />o <br />o <br />o <br />n <br />n <br />n <br />o <br />D <br />o <br />o <br />D <br />D <br />n <br />U <br /> <br />Lesson 3 <br /> <br />Culvert Design - Participant Workbook <br /> <br />3.4 CULVERT FLOW CONDITIONS <br /> <br />CULVERT FLOW CONDITIONS <br /> <br />~ <br />.... <br /> <br />~..'.'.'. <br />. . <br /> <br />. CULVERTS CAN FLOW FULL OR PARTIALLY <br />FULL <br />- water surface profile analysis required to <br />determine part full flow conditions <br />- partly full flow may be 5ubcritical, critical or <br />supercritical <br />- gravity full flow is a special case of free <br />surface flow <br /> <br />~.. <br />F'" m"., , ' , "." <br />"""~""'f' . ..>.... . . <br /> <br />-.. ..... <br />,.W , H.... <br />"""". ..'.;",;1.... <br />. .. <br />..",,.,,.. ,. ~ .. <br />".. '..'''. ... <br />. " ." <br /> <br />3.16 Culvert Flow Conditions <br /> <br />3.17 Flow Conditions Schematic <br /> <br />A. A culvert may flow full over all its length or partially full. Full flow <br />throughout a culvert is rare, and generally some portion of the barrel flows <br />partly full. <br /> <br />1. A water surface profile analysis is the only way to accurately <br />determine how much of the barrel flows full. <br /> <br />2. Pressure flow conditions in a culvert can be created by either high <br />downstream or upstream water surface elevations. <br /> <br />3. Partly full flow, or open channel flow, in a culvert may occur as <br />subcritical, critical or supercritical flow. <br /> <br />B. Gravity full flow, where the pipe flows full with no pressure and the water <br />surface just touches the crown of the pipe, is a special case of free <br />surface flow and is analyzed in the same manner as open channel flow. <br /> <br />C. Based on a variety of laboratory tests and field experience, two basic <br />types of flow control have been defined for culverts: inlet control and <br />outlet control. <br /> <br />CULVERT FLOW CONDITIONS <br /> <br />INLET CONTROL <br /> <br />. CULVERTS CAN FLOW FULL OR PARTIALLY <br />FULL <br />- water surf(l;ce- profile I;'Ulc!ysis required to <br />detvrmine pMt full flQ1,v conditions <br />- partly full how m"y be subcritiC01. clltic.(l1 ,;H <br />supercritic.a! <br />- gr!1lvity fun flow is 11 special C21S0 of h€€ $udace <br />fiow <br /> <br />. DEFINITION <br /> <br />INLET CONTROL OCCURS WHEN THE <br />CULVERT BARREL CAN CARRY MORE <br />FLOW THAN THE INLET WILL ACCEPT <br /> <br />- inlet control <br />- outlet control <br /> <br />. HYDRAULIC CONTROL IS LOCATED JUST <br />INSIDE THE ENTRANCE <br />. DOWNSTREAM CONDITIONS DO NOT <br />INFLUENCE CULVERT CAPACITY <br /> <br />. TWO TYPES OF FLOW CONTROL: <br /> <br />3.18 Culvert Flow Conditions (cont) <br /> <br />3.19 Inlet Control <br /> <br />3-7 <br />