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DISCHARGE OF LIQUIDS]
41
HYDRAULICS

Table of Coejicients of Discharge for Rectangular Vertical Orifices in Fig. 20. Head 1- i Height of oi-mee, H -/1, in feet. 1 above 1-31 0-66 O'I6 0-10 Orifice ' ' '”“ in feet. P Q R P Q R P Q R P Q R 0-328 0-598 0-644 0-648 0-634 0-665 0-668 0-691 o-664 -666 0-710 0-694 0-696 -656 0 609 0-653 0-657 0-640 O'672 0 675 0-685 0-687 -688 0-696 0-704 0-706 -787 0-612 0-655 0-659 0-641 0-674 0-677 0-684 0-690 692 0-694 0-706 0-708 -984 0 616 0-656 0-660 O'64I 0-675 0-678 0-683 0-693 695 0-692 0-709 0-711 1-968 O°6I8 0-649 0-653 0-640 0-676 0-679, 0-678 0-695 I 697 0-688 0-710 0-712 3-28 0 608 0-632 0-634 0-638 0-674 0-676 0-673, 0-694 -695 0-680 l 0-704 0-705 4'27 0 602 0-624 O'626 0-637 0-673 I 0-675 0-672 0-693 -694 0-678 0-701 0-702 4-92 0-598 | O'62O 0-622 0-637 l 0-673 0-674 0-672 0-692 -693 0-676 0-699 0-699 5-58 0-596 0-618 0-620 0-637 0-672 0-673 0-672 0-692 693 0-676 o-098 0-698 6-56 0-595 0-615 0-617 0-636 0-671 0-672 0-671 0-691 -692 0-675 0-696 0-696 9-84 0-592 0-611 0-612 0-634 0-669 0-670 0-668 0-689 '69O 0-672 O-693 VYYY 0-693 For rectangular oritices Q40-62(1+0-152n and for circular orifxces, c, =0'62): when n is the length of the edge of the orifice over which the border extends, and p is the whole length of edge or perimeter of the orifice. The following are the values of cf, when the border extends over }, i or § of the whole perimeter:- fc C Z/P Rectangular Orifices. Circular cOrifices. 0- 25 0-643 -640 0- 50 0-667 -660 0-75 0-691 -680 For larger values of P

T I TK -ill?: "' ' ':..T.TT '€a F .E .

é u~ f 1 1 | J r ~..; - -~-4 ~=.~~»f¢ - Y .- n/p the formulae a Q 1 M pg lx

Q- .1 5

I L v '.T%§ 'iQ'Q:, ¢ 2 2. - ff/ re not applicable. C. R. Bornemann has shown, however, that these formulae for suppressed contraction are not reliable. § 23. Imperfect Cantraction.-If the sides of the vessel approach near to the edge of the orifice, they interfere with the convergence of the streams to which the contraction is due, and the contraction is then modified. It is generally stated that the influence of the sides begins to be felt if their distance from the edge of 4.1 § 24. Orzjices Furnished with Channels of Discharge.-These external borders to an orifice also modify the contraction. The following coefficients of discharge were obtained with openings 8 in. wide, and small in proportion to the channel of approach (fig. 22, A, B, C). hd" hx in l hi in feet. teen ' - -o656 164 '328 '656 1'640 3'28 4'Q2 6'56 984 A -480 '5II -542 574 -599 -601 -601 -601 -601 B 0-656 -480 -510 -538 506 -592 -600 -602 -602 -601 C, l -527 -553 '574 592 -607 '6IO -610 -609 -608 A I-488 -577 -624 631 -625 -624 -619 -613 -606 B go-164 -487 -571 -606 617 -626 -628 -627 -623 -618 C -585 -614 -633 645 -652 -651 -6504 -650 -649 from a horizontal § 25. Inversion of the Jet.-When a jet issues orifice, or is of small size compared with the head, it presents no l ct, 6

the orifice is less than 2-7 49, ,// times the corresponding /*W A R i i 00%, ,J —f 7- ft ' 4

1 2 . /, ,

I | I V

T I- . .. 1 / /

T ' “ .i 'P l 'l . *= I # ' . 1. v-§ Q | -Q Y4 ' H- ra Q + j; i FIG. 20. FIG. 21. I T FIG- 23- V width of the orifice. The coefficients of contraction for this case | marked peculiarity of form. But if the orifice is in a vertical surare imperfectly known. face, and if its dimensions are not small com ared with the head, P A, B C,

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"T""" '"'Z'”"" l ffiififflfii Ill hi hi! ', IB i I .1 a 5 = ka 4 I $§ -; -. " i , , ' ' ~—, lil-;§ » -lir;:i;::*"'~ ~~ ' ~ Ji- — rfq '1'53~"1f§ l?57?<§ ', Z ' iI'l". “ "2 Q 'i - ~—10 — — »i l SI/qw 1 in- 20 4 7 '» l i FIG. 22. l<1°""""“'*9"“""""”"

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