- .
Z1+P1/ρg+U1^2/2g= Z2+P2/ρg+U2^2/2g+h - , - . - -:
1. 2. , R , . 3. - - .
. - - - - -:
X- - =0 Uy=0 u Uz=0 =>
y- - =0 y- - =0
z- - =0 z- - =0 (1)
(1) - . Z+P/ρg =const; P=Po+ρgh - : α=(u)/(υ); α= : H̕ ̶>H Z+P/ρg+U^2/2g=H́ - ω. : 1.- H́ - dt. 2. - - - ω V. 3. - - - ,- 1- - ω dt .
15. - - -. P P
P1/pg P2/pg
1 2
Z1 Z2
0 0
Z+P/ρg->H̕; Hp̕- -
z - , ; P/g , ; u2/(2g)=hu ; ,
U^2/2g
dl
Z+P/ρg+U^2/2g=Z+P/ρg+U^2/2g
1 2 U=0; P/ρg-P/ρg= U^2/2g hu
U^2/2g- . - : - - , - , - , - - - . - > , .. - -.
. - -.- - - -.
( ) , - 2 -: (- ) ( - ). , , . . Re=Vl/ν ν -- . , : Rer= VR/ν; R- = . R=w/χ Re, - - R=d/4 Re=2320/4=580 Re>Re , Re<Re .
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τ0
τ- - - .
τ0=pgIR- -
I- . I=h/l R- R= w/χ
17.- , -, . - - , - , 0 , , . - - - - U=0. - - -: τ=+-*dU/dr; τ=pgIR; R=r*1/2; pgIRr/2=- *dU/dr dU= pgIR*r/2*1/ dr; U=1/2*pg/*I*1/2*r^2+C C=1/4* pg/*I*r0^2; U=1/4* pg/*I(r0^2-r^2) r=r0 U=0; r=0 U=max Umax=1/4* pg/*I*r0^2=1/16* pg/*I*d^2- . - - -. dQ=Udω=1/4* pg/*I(r0^2-r^2)*2πr*dr Q=∫1/4* pg/*I(r0^2-r^2)*2πr*dr=1/8*pg/*I* πr0^4 V=Q/ω; V=1/128*pg/*I* πd^4; V=1/32* pg/*h/l*d^2 h=Vl32/ρgd^2 - (1- )
h=Vl32/ρgd^2 *(Vr*V/2V)=64/Re*(C*V^2/2g) 64/Re=λ- - h=λ*l/d*V^2/2d/g
18. . - - - - - - - . - - - - - -.
- - : ( ), .
- - δ - , - Re. Re δ→0-.
δ>=Δ- , δ<=Δ- .
Δ- .
19. - -. 1. -. -. Re<2320. - λ Re λ =Re/64. : h=64ν/Vd*l/d*V^2/2g=kV: k-- . - , , - - -. 2320 < Re < 20d/ 2- - -. , 5 Δ, . - - λ Re, . . λ, = f(Re). h=kV^1/75. - - λ - - : λ=0.3164 /Re^0.25 3- - - , - λ 2 : Re .h=kV^1.75-2.0 20 d/ Δ <Re<500 d/ Δ - λ, - .. : λ=0.11(68/Re+d/ Δ)^0.25 4- - - - - - , , - λ . h=kV^2.0; Re >500 d/ Δ - λ - - .. : λ= 0,11 (d/ Δ)^0.25
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20.- .- -. - - λ -, , , . . .. , - , -*, - λ=f(Re,). λ Re . 1 -. λ =Re/64 2- - - λ=0.3164 /Re^0.25 3- - - λ=0.11(68/Re+d/ Δ)^0.25 4- - λ= 0,11 (d/ Δ)^0.25
21. - -. - , . . . , - λ Re - - h=λ*l/d*V^2/2g; d=4R; V=
h/l=I=i→ =c- - .
V=c* - - . - λ. =1/n*R^1/6 n-- n=0.021..0.025 h=il→i=V^2/c^2R; c^2R=W h= V^2/c^2R*l Q=wc ;i=(Q^2/R^2)*l
, h =(Q^2/R^2)*l - .