Page 164 - Fluid-Structure Interactions Slender Structure and Axial Flow (Volume 1)

146 SLENDER STRUCTURES AND AXIAL FLOW

20

16

9
12

E

4‘ I I I I
100 200
Y
Figure 3.53 Theoretical and experimental values of urf for experiments with a vertical
cantilevered rubber pipe conveying water (j3 = 0.622), fitted with different end-nozzles (different
ai = A/A-)- curves with data points, experiments; curves without, theory. Dissipation modelled by
:.
viscoelastic model: a = 0.003, 0.0025 and 0.002 for aj = 1, 1.5 and 2.49, respectively (Bishop &
Fawzy 1976).

exerted thereon. The measured dimensionless critical flow velocity was found to be
ucf = 4.45 (Ucf 2 150m/s), which is within 6% of the theoretical.
An extensive experimental programme (see Section 3.6) was undertaken by
Jendrzejczyk & Chen (1985) and Chen & Jendrzejczyk (1985). They conducted two
experiments with polyethylene cantilevered pipes (0, = 9.5 and 12.7mm, h = 1.59mm
and L = 609.6 mm) mounted vertically and conveying water. They obtained excellent
agreement between theory and experiment, as illustrated by Table 3.5. The r.m.s.

Table 3.5 Jendrzejczyk & Chen’s (1985) results for cantilevered polyethylene
pipes conveying water.
~~ ~~
Test no. vc f (ds) Qcf/2n (Hz)
Theory Experiment Theory Experiment
1.1 25.0 24.9 12.9 12.0
1.2 30.7 31.4 16.0 14.5