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absolute velocity actual discharge angle approximate axis canal canal lock cent centre centre of pressure channel circular coefficient of discharge coefficient of velocity computed conduit crest cross-section cubic feet cubic foot curve deduced depth determined direction discharge per second distance dynamic pressure edge effective head efficiency end contractions equal equation experiments expression feet per second formula friction given gives greater head h hence horizontal horse-power hydraulic radius impulse inserted length less loss of head mean velocity measured method miner's inch motion nozzle occurs penstock piezometer pipe plane pounds per square pressure-head Prob quantity of water reaction wheel reservoir resistances revolutions per minute shown slope square inch standard orifice stream theoretic discharge theoretic energy tion tube turbine V2gh vane velocity of approach velocity of flow velocity-head vessel water level water surface weight weir wetted perimeter wheel
Page 288 - ... Motor. The total available head H between the surface of the water in the reservoir or head-race and that in the lower pool or tail-race, is determined by running a line of levels from one to the other. Permanent bench-marks being established, gauges can then be set in the head-race and tail-race, and graduated so that their zero points will be at some datum below the tailrace level. During the test of a wheel^ each gauge is read by an observer at stated intervals; and the difference of the readings...
Page 293 - It is seen that this method is independent of the radius of the pulley, which may be of any convenient size. For a small motor, the brake may be clamped directly upon the shaft; but for a large one a pulley of considerable size is needed, and a special arrangement of levers is used, instead of a cord.
Page 292 - ... by two bolts. By turning the nuts on these bolts while the pulley is revolving, the friction can be increased at pleasure, even to the extent of stopping the motion; around these bolts, between the blocks, are two spiral springs (not shown in the diagram) which press the blocks outward when the nuts are loosened. To one of these blocks is attached a cord, which runs horizontally to a small movable pulley over which it passes, and supports a scale pan in which weights are placed. This cord runs...
Page 287 - If it be very small, it may 110 be caught in pails and directly weighed. If large in quantity, the gates which admit water to the wheel may be closed, and the leakage being then led into the tailrace, it may be there measured by a weir, or by .allowing it to collect in a tank. The leakage from a vertical penstock whose cross-section is known, may be ascertained by filling it with water, the -wheel being still, and then observing the fall of the water level at regular intervals of time.
Page 286 - ... flow in, the time between the beginning and end of the experiment being determined by a stop-watch, duly tested and rated. This time must not be short, in order that the slight errors in reading the watch may not affect the result. The gauge is read at the close of the test after the surface of the water becomes quiet, and the difference of the gauge-readings gives the depth which has flowed in during the observed time. The depth multiplied by the area of the cross-section gives the volume, and...
Page 25 - ... is the sum of the products obtained by multiplying each element of the area dA by the square of its distance from the axis.
Page 293 - ... .shaft is disconnected from the machinery which it usually runs, and is allowed to revolve, transforming all its work into heat by the friction between the revolving pulley and the brake, which is kept stationary by tightening the nuts and at the same time placing sufficient weight in the scale-pan to hold the pointer at the fixed mark. Let n be the number of revolutions per second, as determined by a counter attached to the shaft...
Page 288 - H is then directly read by noting the point of the graduation which coincides with the water surface in the tube. This device requires but one observer, while the former requires two; but it is usually not the cheapest arrangement, unless a large number of observations are to be taken. From this total head...