2.4.3. Tinh hm IUQ1lgdon vi va cao dq duimg bao bOa trong than dip,tren nen kh6ng tharn tren nen kh6ng tharn
1. C6ng thuc cO'ban
thdm
v m dong thdm bi8n d6i deu (duOng bao hoa bi8n d6i deu ) nhu hinh ve (2-13). Luu IUQ1lgthdm dan vi q dugc tinh theo ding thuc sau:
z z
q= k Y,-Yz
2L (2-9)
q: Luu IUQ1lgthdm dan vi (rn3/s.rn)k: h~ s6 thdm clla ddt(mls). k: h~ s6 thdm clla ddt(mls).
L: khoang cach theo phuang ngang gifra 2 rni;itc~t xet (1-1 &2-2)( rn).
Yt. Y2::E>9sau ( thlmg goc ) clla dUOng bao bOa tll-irni;itc~t 1-1 &2-2 ( rn ).
(2-10)
B€ img d1)Ilg dugc phuong trioo Buy Puy, ta tuang tugng keo diin dUOng biio hOaaphdn giap mw thugng v~ thugng luu d€ dUOng biio hOa la bi8n d6i d~u ( hinh 2-14). LUc nay ta co th€ xem mw thugng luu la thAng dimg va di qua di€m cach mep nucrc thugng luu mQt do(U1la &.Nhu v~y ta co th€ img d1)Ilg phuong triOOBuy Puy d€ tinh q cho d~p.
Trj s6 &co th€ xac djnh theo cong thuc CK MikhaiL6p OOu sau:
&=H1. ml
2ml+!
2. Truemg h(TJJhq lUll kh6ng co thih hi thoat nuac
Q.Khi hq lUll co nuac.
Gia su co mQt ~p dftt lilm vi~c theo sad6 OOuhiOO ve ( hiOO2-14). Vi8t phuong trinh Buy Puy cho m~t c~t dAu va cu6i cua dUOng biio hOa: - Cong thuc tiOO luu lugng don vi q
=k H~-h~
q . 2L
I
(2-11)
k: H~ s6 thfun Clla d~t than d~p (m/s).
L1: Khoimg cach bAng gifra 2 m~t c~t xet ( m ).
HI. hI: CQt nucrc thugng luu va dQ cao dUOng biio hoa (tiOO tir day d~p) tlili di€m ra amai hlilluu ~p ( m ).
LI =L -m2 hI
hI =ho + 1Io
Trj s6 1Ioco th€ tiOOtheo cong thuc Clla A.E. Dumarin:
(2-12)
y ",L B Do ~..~. ...~. L, L Hinh 2-14
- Phuong trinh du<'mgbao hOa trong than d~p.Ch<;mh~ tn,Ic tQa d() xoy OOuhiOO(2-14). Ch<;mh~ tn,Ic tQa d() xoy OOuhiOO(2-14).
(2-13)
",L B
a. Khi h(1hru khOng co mrac.
Tru<'mg hgp nay, cong thuc (2-12) chi vi~c lfty ho=0 ta se tinh duQ'c!to, sau do lfty hj =!to ta se tinh duQ'c q theo (2-11); phuong triOO du<'mg bao hoa trong than d~p v~n xac diOOtheo (2-13).
3. TruOng hr;rph(1ltru co d8ng &1thoat nuac a. Khi h(1 hru co nuac.
Gia Slr co m()t d~p dftt lam vi~c theo sa d6 OOuhiOO 2-15.
L1
L
Hinh 2-15
Gia thi6t du<'mg bao hoa ch(lYti6p xu6ng giap vm m\!c nuac h(lluu (di~m 0)
OOu hiOO(2-15)
Vi6t phuong triOOBuy Puy cho m(it ciit ddu va cu6i cua du<'mgbao hoa - Cong thuc tiOO luu luqng don vi q
1
- k.Hi -h~
q - 2L
L=L, +1
Tri 86Ico the tinh theo cong thii'c:
- Phucmg trinh duang biio hOa trong than d~p.Ch9n h~ tI\1c t9a dQ xoy nhu hinh (2-15).