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Fig. 2. Relative thermal hydraulic characteristics of CC at various angles

β

( — 20

; — 30

;

N

— 45

):

a

— is a thermal characteristic,

b

— is a hydraulic characteristic

with the Re number growing,

η

Nu

characteristic decreases monotonically,

which signifies a gradual degeneracy of the convective heat transfer

intensification. The relative hydraulic characteristic

η

ξ

has a tendency

towards the optimum (min) in the laminar to the turbulent flow transition

zone. The peculiar feature of these characteristics is the fact that the heat

transfer intensification rate exceeds the hydraulic drag increase rate in

the area of a transition mode and moderate crossing angles. However, at

β

= 35

. . .

45

an increase in

η

ξ

is faster than in

η

Nu

(Fig. 3).

On the assumption that CC is a special design type of the circular

finned channel, its efficiency evaluation can be performed on the basis of

the methodology previously suggested [1]. It states that the maximum heat

transfer efficiency of the circular finned cooling channels can be calculated

ISSN 0236-3941. HERALD of the BMSTU. Series Mechanical Engineering. 2015. No. 2 47