. . , , , . .
Wx=Wmax(1-(r/r0)2)
Wmax=2 W
. . . . , .
.
:
Nuf,x=0,33× Ref,x0,5×Pr f0,43× (Prf∕ Prw)0,25(x∕d) 0,1
(x∕d) 0,1- ., d- . Re=(ω× d) ∕ν
Re() <2300, Re() >104, Re()=2300104
:
Nuf, d =0,022× Re f,d 0,8×Pr0,43× εℓ 104 < Re <5×106
0,6 < Pr<2,5×103
εℓ .
(x∕d) >=15, εℓ=1, εℓ=1,38(x∕d)-0,12