Severe vibrations were observed in a small piping system comprising two elbows and straight sections configured in the form of a U and subjected to air-water internal two-phase flow. An experimental study was undertaken to investigate the governing vibration excitation mechanism. Vibration response, excitation forces, and fluctuating properties of two-phase flow were measured over a wide range of flow conditions. The results show that the observed vibrations are due to a resonance phenomenon between periodic momentum flux fluctuations of two-phase flow and the first modes of the piping system. The excitation forces consist of a combination of narrow-band and periodic components, with a predominant frequency that increases proportionally to flow velocity. For a given void fraction, the force spectra for various flow velocities and elbow geometries show little scatter on a plot of a normalized power spectral density as a function of a dimensionless frequency. The predominant frequencies of excitation agree with recent results on the characteristics of periodic structures in two-phase flow.

1.
Pettigrew
,
M. J.
, and
Taylor
,
C. E.
, 1994, “
Two-Phase Flow-Induced Vibration: An Overview
,”
ASME J. Pressure Vessel Technol.
0094-9930,
116
, pp.
233
253
.
2.
Chen
,
S. S.
, 1991, “
Flow-induced Vibration in Two-Phase Flow
,”
ASME J. Pressure Vessel Technol.
0094-9930,
113
, pp.
234
241
.
3.
Hara
,
F.
1980, “
Two-Phase Flow-Induced Parametric Vibrations in Structural Systems—Pipes and Nuclear Fuel Pins
,” Report of the Institute of Industrial Science, University of Tokyo,
28
, pp.
1
43
.
4.
Monette
,
C.
, and
Pettigrew
,
M. J.
, 2004, “
Fluidelastic Instability of Flexible Tubes Subjected to Two-Phase Internal Flow
,”
J. Fluids Struct.
0889-9746,
19
, pp.
943
956
.
5.
Misra
,
A. K.
,
Païdoussis
,
M. P.
, and
Van
,
K. S.
, 1988, “
On the Dynamics of Curved Pipes Transporting Fluid. Part I: Inextensible Theory
,”
J. Fluids Struct.
0889-9746,
2
, pp.
221
244
.
6.
Yih
,
T. S.
, and
Griffith
,
P.
, 1970, “
Unsteady Momentum Fluxes in Two-Phase Flow and the Vibration of Nuclear System Components
,”
Proceedings of the International Conference on Flow-Induced Vibrations in Reactor System Components
, Argonne IL Report ANL-7685, pp.
91
111
.
7.
Baumeister
,
K. J.
,
Graham
,
R. W.
, and
Henry
,
R. E.
, 1973, “
Momentum Flux in Two-Phase Two-Component Low Quality Flow
,”
AIChE Symp. Ser.
0065-8812
69
(
131
), pp.
46
54
.
8.
Taitel
,
Y.
,
Barnea
,
D.
, and
Dukler
,
A. E.
, 1980, “
Modelling Flow Pattern Transitions For Steady Upward Gas-Liquid Flow in Vertical Tubes
,”
AIChE J.
0001-1541
26
(
3
), pp.
345
354
.
9.
Riverin
,
J.-L.
, 2004, “
Étude des forces fluctuantes dans des éléments de tuyauterie soumis à des écoulements diphasiques internes (Study of Fluctuating Forces in Piping Elements Subjected to Internal Two-Phase Flow)
,” Masters thesis, Department of Mechanical Engineering, École Polytechnique de Montréal, December.
10.
Morris
,
D.
,
Teyssedou
,
A.
,
Lapierre
,
J.
, and
Tapucu
,
A.
, 1987, “
Optical Fiber Probe to Measure Local Void Fraction Profiles
,”
Appl. Opt.
0003-6935
26
(
21
), pp.
4660
4664
.
11.
Riverin
,
J.-L.
,
de Langre
,
E.
, and
Pettigrew
,
M. J.
, 2006 “
Fluctuating Forces Caused by Internal Two-Phase Flow on Bends and Tees
,”
J. Sound Vib.
0022-460X
298
pp.
1088
1098
.
12.
Thomson
,
W. T.
, and
Dahleh
,
M. D.
, 1998,
Theory of Vibration with Applications
,
5th ed.
,
Prenctice-Hall
, Englewood Cliffs, NJ.
13.
Azzopardi
,
B. J.
, and
Baker
,
G.
, 2003 “
Characteristics of Periodic Structures in Gas∕Liquid Two-Phase Flow
,”
Proceedings of UK∕Japan Two-Phase Flow Meeting
,
Guildford UK
, Apr. 14–15.
You do not currently have access to this content.