Water-power; an outline of the development and application of the energy of flowing water . ve the bottom. When // = o, A // We can draw the two lines representing the forces acting on the dam. Fromm, their intersection, we lay off the vertical ml to representthe weight of the dam, and the horizontal vto to represent thepressure. Complete the rectangle inlno and draw the diagonalmn. This represents the resultant of the forces acting on thedam, and must, according to the above rule, fall within themiddle third of the base. If this condition is not fulfilled, wemust redraw the figure with a diff
Water-power; an outline of the development and application of the energy of flowing water . ve the bottom. When // = o, A // We can draw the two lines representing the forces acting on the dam. Fromm, their intersection, we lay off the vertical ml to representthe weight of the dam, and the horizontal vto to represent thepressure. Complete the rectangle inlno and draw the diagonalmn. This represents the resultant of the forces acting on thedam, and must, according to the above rule, fall within themiddle third of the base. If this condition is not fulfilled, wemust redraw the figure with a different value of Be or adifferent inclination of BC. Fig. 8 represents the construction when the up-stream faceis inclined and the down-stream face vxTtical. In this case> 26 DA MS FOR WA TER-PO WER. putting c to represent the side AB, the pressure on the incHned IH \face is jr^ j- //]. Moment with reference to A IH h\ = jiic . \Hc + \cJu) = yc\-^ + -j. c! h \ (8) i is the common centre of gravity, m the intersection of thetwo forces, mo represents the pressure, ml the weight, mlno the. Fig. 8. parallelogram of forces, ;;/;/ the resultant. The width Be, orthe inclination of AB, must be varied till mn intersects thebase at the right point. Form with Reference to Discharge.—The cross-section iso-ovcrned, secondly, by the consideration of passing the waterin a manner to expose the dam to as little injury or chance ofinjury as possible. To understand the conditions of thisrequirement, we must examine attentively the action of falling FORM WITH REFERENCE TO DISCHARGE. 27 water. When a sheet of water falls over the perpendicularface of a dam, and strikes on a level surface, the stream, atcertain stages, takes the form shown at Fig. 9. It changes its
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthydraulicengineering
