Mechanics of engineering.(fluids) comprising the principles of hydraulics and pneumatics, with applications, for use in technical schools - Softcover
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 Excerpt: ... IL--Fig. 543. With what velocity, tm, will watei flow into the condenser O of a steam-engine where the tension of the vapor is pm, one atmosphere, if h = the head of water, and the flow takes place through an orifice in thin plate? Taking position m in the contracted section where the filaments are parallel, and the pressure therefore equal to that of the surrounding vapor, viz.,?TO, and position n in the (wide) free surface of the water in the tank, where (at surface) the pressure is one Flo. atmosphere and.-.--= b = 34 ft. and velocity practically zero; we have, applying Bernoulli's Theorem to » and m, taking To as a datum level for potential heads (so that sn = h and and Q = Fmvm,....., (9) as theoretical results. But practically we must write in which _= area of orifice in thin plate, and C=. coefficient of contraction = about 0.62 approximately see § 495. Example.--If in the condenser there is a " vacuum" of 27J inches (meaning that the tension of the vapor would support 2f inches of mercury, in a barometer), so that Pn = fr X 11. T Ibs. per sq. inch, and h--12 feet, while the orifice is £ inch in diameter; we have, using the ft., ib., and sec., = 51.1 ft. per sec. (We might also have written, for brevity, = 2: 30 X 34 = 2.833, since the pressure head for one atmos. = 34 feet, for water. Hence, for a circular orifice in thin plate, we have the volume discharged per unit of time, Q = CFv-0.62 X jNy X 51.1 = 0.0431 cub. ft. per sec. 497a. Efflux through an Orifice in Terms of the Internal and External Pressures.--Fig. 544. Let efflux take place through a small orifice from the plane side of a large tank, in which at the level of the orifice the hydrostatic pressure was = p' before the opening of the orifice, that of the medium s...
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