Begell House Inc.
Multiphase Science and Technology
MST
0276-1459
14
3
2002
FLUCTUATION MEASUREMENTS IN A VERTICAL UPWARD AIR/WATER FLOW
24
10.1615/MultScienTechn.v14.i3.10
F.
Le Gall
ERES-Innovation Phys. Therm. 10 rue Vauquelin, 75231 Paris Cedex 05, France
S.
Pascal-Ribot
CEA Cadarache DTP/STH/LTA Bat. 21913108 St Paul-lez-Durance, France
J.
Leblond
ESPCI, Laboratoire de Physique et Mechanique des Milieux Heterogenes, URA C.N.R.S. 857, 10 rue Vauquelin, 75231 Paris cedex 05, France
The general objective of the present work is to contribute to the understanding of the interactions between a structure and a two-phase flow by investigating the fluctuations of the liquid mass flux, the liquid momentum flux, the pressure at the wall, and of the local void fraction in a two-phase air water mixture flowing in a vertical pipe.
The fluctuations of the mass and momentum fluxes were determined by means of nuclear magnetic resonance whereas the fluctuations of the pressure at the wall were measured by a piezo-electric transducer. In addition, measurements of the fluctuations of the local void fraction were performed with an optical probe.
The experiments were carried out in two pipe configurations: (I) a standard smooth pipe and (II) a pipe containing a series of perforated plates normal to the pipe axis. In both configurations, measurements are performed at approximately the same distance from the pipe entrance. In configuration (I) the measurements were made at the end of the pipe whereas they were made downstream from the last perforated plates in configuration (II).
The RMS amplitudes of the liquid mass flux, the liquid momentum flux, the pressure at the wall, and of the local void fraction are investigated in bubbly and churn-turbulent flows as functions of the mean void fraction. Moreover, the behavior of these fluctuations are analyzed in the frequency domain.
These analyses clearly showed that the pressure fluctuations behave quite differently from the other measured quantities. This different behavior leads us to propose new scaling parameters for the wall pressure spectra. Results corroborate the role of void fraction on the structure vibrations.
SYSTEMATIC TESTING OF THE TWO-PHASE PRESSURE-DROP EQUATIONS FOR HORIZONTAL DIVIDING T-JUNCTIONS
40
10.1615/MultScienTechn.v14.i3.20
M. L.-J.
Levac
Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
Hassan M.
Soliman
Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
Barry J.
Azzopardi
Department of Chemical, Environmental and Mining Engineering, The University of Nottingham, University Park, Nottingham NG7 2RD, England
G. E.
Sims
Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
A study was conducted in order to assess the state of the art in predicting the pressure changes during two-phase flow in horizontal dividing T-junctions. A database was established from data generated at various research laboratories. This database included results for air-water and steam-water mixtures, pressures from near atmospheric to 10 MPa (100 bar), equal-sided and reduced junctions, wide ranges of the inlet gas and liquid superficial velocities, and the full spectrum of inlet flow regimes. Seven empirical models were considered in the present study; all of which include equations for predicting the pressure changes at the junction. It is demonstrated that none of these models is capable of good prediction over the whole range covered by the database. Some models produced good predictions for the data sets from which these models were developed, but large deviations against other data sets. Finally, the database was divided into segments according to the inlet flow regime and it is shown that, in most instances, it is possible to recommend specific models for predicting the pressure changes associated with each regime with good accuracy.