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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