18.08.2015   NUCLEAR POWER PLANTS

Regimes

(Kim et al., 2009) have carried flow induced vibrations (Experimental study of two circular cylinders in tandem arrangement) and examined three different experimental conditions both cylinders allowed to vibrate, the upstream cylinder is allowed to vibrate with the downstream cylinder fixed and downstream cylinder allowed to vibrate with upstream cylinder fixed. The results include five regimes depending upon ^/q, fluctuating lift forces and vibration characteristics of the cylinder as given in Table 3.

Regimes

I

II

III

IV

V

Range

°d <% > 0.2

0.2 <%> 0.6

0.6 <%> 2.0

2.0 <%> 2.7

%> 2.7

Response

Vibration

absent

Violent vibrations of both For Ur > 6

Convergent vibrations at Ur « 6.7

Vibration

absent

Each vibrating like isolated cylinder at Ur « 6.7

Characteristics

Vibration amplitude is strongly dependant on whether upstream cylinder is fixed or vibrating

Upstream

cylinder

vibration is

completely

suppressed

when

downstream cylinder is fixed but the downstream cylinder is independent of upstream cylinder.

Downstream vibration is strongly dependant on upstream cylinder but upstream cylinder vibrations is insensitive to downstream cylinder.

Table 3. Regimes of vibration for Circular cylinders tandem (Kim, et al., 2009)