. Bulletin of the Department of Agriculture. Agriculture; Agriculture. PART I. FLOW IN PRESSURE PIPES, FORMULAS FOR FLOW OF WATER IN CONCRETE PRESSURE PIPE. Water is caused to flow and velocity created by the force of gravity. Thus the flow follows the general law of falling bodies, and the velocity tends to become constantly accelerated. This tendency is just bal- anced by the influences retarding the flow. For a pipe carrying flowing water under pressure, the difference in elevation HE (fig. 1), between the surfaces of the water at the intake and outlet is the effective head through whi
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. PART I. FLOW IN PRESSURE PIPES, FORMULAS FOR FLOW OF WATER IN CONCRETE PRESSURE PIPE. Water is caused to flow and velocity created by the force of gravity. Thus the flow follows the general law of falling bodies, and the velocity tends to become constantly accelerated. This tendency is just bal- anced by the influences retarding the flow. For a pipe carrying flowing water under pressure, the difference in elevation HE (fig. 1), between the surfaces of the water at the intake and outlet is the effective head through which the force of gravity acts. The effective or lost head is made up of several individual losses as follows (fig. 1): V2 Velocity head = hv = -~- (1) z9 This is the head absorbed in creating the mean velocity V, at which the water is conveyed through the pipe. This loss occurs at the Elevat/on E/\ â ⢠~-!lf. if* Fig. 1.âHydraulic elements for loss of head in siphon pipe. intake. As a rule, little or none of this velocity head is recov- ered at the outlet of the pipe. Entry head, he = ^ (approximately) (2) The- amount of loss at the entry, due to the effect of contraction eddies and other retarding influences, is variable and uncertain, but most authorities agree that it should be taken as half the velocity head, unless the inlet structure is especially designed to'minimize this loss. For further discussion see page 52. Friction head, 7if, is that lost in overcoming the retarding influences within a reasonably straight pipe. In pipes of great length, the amount of this loss so far exceeds the two losses first mentioned that they often may be neglected, especially in small pipes. This is the loss upon which the experiments described in this paper were con- centrated. 5. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble
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