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24 papers
Short Communications
Anomalous intensification of a turbulent separated flow in inclined, single-row, oval-trench dimples on the wall of a narrow channel
S. A. Isaevab,
M. S. Gritckevichb,
A. I. Leont'evc,
I. A. Popova,
A. G. Sudakovb a Kazan National Research Technical University named after A. N. Tupolev
b Saint-Petersburg State University of Civil Aviation
c Bauman Moscow State Technical University
Abstract:
In a long, plane-parallel channel with single-row, inclined, oval-trench dimples on the wall, a periodic section with a relative length of
$8$ (the distance between centers of neighboring dimples), a width of
$9$, a height of
$1$, and a centrally located, inclined, oval-trench dimple with a length of
$7.05$, a width of
$1.05$, a depth of
$0.25$, and with variation in the inclination angle from
$1^{\circ}$ to
$89^{\circ}$ is considered. An anomalous intensification of a separated turbulent air flow in an inclined dimple at the Reynolds number of
$10^4$ is discovered. At an inclination angle of
$60^{\circ}$, the maximum absolute value of negative friction in the middle longitudinal cross-section exceeds the friction in a plane-parallel channel by more than
$2.5$ times. The cause of this phenomenon is related to the formation of a high pressure drop between the closely located zones of stagnation and low pressure in the semispherical inlet segment of the dimple.
UDC:
532.517:4
Received: 07.11.2018
Revised: 13.12.2018
Accepted: 25.12.2018
DOI:
10.1134/S0040364419040082