Two-Phase Flow-Induced Forces on Bends in Small Scale Tubes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
M. F. Cargnelutti ◽  
S. P. C. Belfroid ◽  
W. Schiferli
Keyword(s):  
Experimental Data ◽  
Structural Integrity ◽  
Two Phase Flow ◽  
Experimental Results ◽  
Small Scale ◽  
Phase Flow ◽  
Momentum Exchange ◽  
Two Phase ◽  
Worst Case ◽  
Good Agreement

Two-phase flow occurs in many situations in industry. Under certain circumstances, it can be a source of flow-induced vibrations. The forces generated can be sufficiently large to affect the performance or efficiency of an industrial device. In the worst-case scenario, the mechanical forces that arise may endanger structural integrity. Thus, it is important to take these forces into account in designing industrial machinery to avoid problems during operation. Although the occurrence of such forces is well known, not much is known about their magnitudes because, unfortunately, the amount of experimental data available in literature are rather limited. This paper describes the experiments performed to measure forces in 6 mm diameter tubing containing a bend. Experiments are performed on bends of different radii, with the bend positioned horizontally or vertically. The experimental results are analyzed based on flow regime and bend configuration. A comparison with available experimental results for bigger internal pipe diameter shows a general good agreement. To improve future predictions, a simple model based on momentum exchange is proposed to estimate the forces generated by multiphase flow. The proposed model shows a good agreement with the experimental data.

Two-Phase Flow-Induced Forces on Bends in Small Scale Tubes

2009 ◽  
Author(s):  
Marcos F. Cargnelutti ◽  
Stefan P. C. Belfroid ◽  
Wouter Schiferli
Keyword(s):  
Experimental Data ◽  
Slug Flow ◽  
Structural Integrity ◽  
Two Phase Flow ◽  
Small Scale ◽  
Phase Flow ◽  
Mechanical Forces ◽  
Two Phase ◽  
Or Efficiency ◽  
Flow Induced Vibrations

Two-phase flow occurs in many situations in industry. Under certain circumstances, this can be the source of flow-induced vibrations. The forces generated can be sufficiently large to affect the performance or efficiency of an industrial device. At worst, the mechanical forces that arise may endanger structural integrity. Thus, it is important to take these forces into account in designing industrial machinery to avoid problems during operation. Although the occurrence of such forces is well-known, not much is known about their magnitudes. Unfortunately, the amount of experimental data available in literature is rather limited. This paper describes an investigation into the forces in a two-phase flow in a 6mm pipe containing a bend. The results are analyzed based on flow regime and bend configuration. Finally, a simple model is proposed to predict the forces generated by slug flow.

scholarly journals Validation of NEPTUNE-CFD Two-Phase Flow Models Using Experimental Data

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Jorge Pérez Mañes ◽  
Victor Hugo Sánchez Espinoza ◽  
Sergio Chiva Vicent ◽  
Michael Böttcher ◽  
Robert Stieglitz
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Model Parameters ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Flow Models ◽  
Phase Models ◽  
Good Agreement

This paper deals with the validation of the two-phase flow models of the CFD code NEPTUNEC-CFD using experimental data provided by the OECD BWR BFBT and PSBT Benchmark. Since the two-phase models of CFD codes are extensively being improved, the validation is a key step for the acceptability of such codes. The validation work is performed in the frame of the European NURISP Project and it was focused on the steady state and transient void fraction tests. The influence of different NEPTUNE-CFD model parameters on the void fraction prediction is investigated and discussed in detail. Due to the coupling of heat conduction solver SYRTHES with NEPTUNE-CFD, the description of the coupled fluid dynamics and heat transfer between the fuel rod and the fluid is improved significantly. The averaged void fraction predicted by NEPTUNE-CFD for selected PSBT and BFBT tests is in good agreement with the experimental data. Finally, areas for future improvements of the NEPTUNE-CFD code were identified, too.

Mach Number Scaling of Single-Component, Two-Phase Flow

1993 ◽  
Vol 115 (4) ◽  
pp. 772-777
Author(s):  
D. E. Nikitopoulos
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Critical Mass ◽  
Critical Flow ◽  
Phase Flow ◽  
Homogeneous State ◽  
Two Phase ◽  
Good Agreement

A simple two-fluid formulation is used to investigate compressibility effects and Mach number scaling for equilibrium, evaporating two-phase flow. The definition of the local two-phase Mach number emerges from a critical flow analysis. Comparisons of the theoretical critical mass flux with existing experimental data obtained in steam-water flows show very good agreement for moderate and high qualities over a wide critical pressure range. Within this quality range the predicted critical mass flux is quite insensitive to the velocity ratio. The analysis confirms previous observations, based on homogeneous flow models, indicating that in variable area ducts the critical state does not occur at a geometrical throat. Results of existing critical flow experiments in slowly diverging ducts are discussed in the light of this conclusion. A way from the neighborhood of the flash horizon, pressure-drop and kinetic energy changes are shown to scale with similar local Mach functions as those of single-phase compressible flow. Existing experimental data from vertical-upwards and horizontal two-phase flows in pipes indicate that the Mach number calculated on the basis of the local homogeneous state provides the optimum scaling performance. Scaling of the same experimental data using a Mach number based on the local nonhomogeneous state provides results that are in reasonably good agreement with the theoretical scaling guidelines and predictions, but is handicapped by considerable scatter in the scaled experimental variables.

Evaluation of Advanced Two-Phase Flow and Combustion Models for Predicting Low Emission Combustors

2000 ◽  
Vol 123 (4) ◽  
pp. 817-823 ◽  
Author(s):  
G. Klose ◽  
R. Schmehl ◽  
R. Meier ◽  
G. Maier ◽  
R. Koch ◽  
...  
Keyword(s):  
Experimental Data ◽  
Two Phase Flow ◽  
Numerical Models ◽  
Computational Method ◽  
Phase Model ◽  
Combustion Model ◽  
Phase Flow ◽  
Two Phase ◽  
Low Emission ◽  
Good Agreement

The development of low-emission aero-engine combustors strongly depends on the availability of accurate and efficient numerical models. The prediction of the interaction between two-phase flow and chemical combustion is one of the major objectives of the simulation of combustor flows. In this paper, predictions of a swirl stabilized model combustor are compared to experimental data. The computational method is based on an Eulerian two-phase model in conjunction with an eddy dissipation (ED) and a presumed-shape-PDF (JPDF) combustion model. The combination of an Eulerian two-phase model with a JPDF combustion model is a novelty. It was found to give good agreement to the experimental data.

Average Volumetric Concentration in Two-Phase Flow Systems

1965 ◽  
Vol 87 (4) ◽  
pp. 453-468 ◽  
Author(s):  
N. Zuber ◽  
J. A. Findlay
Keyword(s):  
Experimental Data ◽  
Two Phase Flow ◽  
Weighted Average ◽  
Phase Flow ◽  
Nonuniform Flow ◽  
Volumetric Concentration ◽  
Two Phase ◽  
Wide Pressure Range ◽  
Wide Pressure ◽  
Good Agreement

A general expression which can be used either for predicting the average volumetric concentration or for analyzing and interpreting experimental data is derived. The analysis takes into account both the effect of nonuniform flow and concentration profiles as well as the effect of the local relative velocity between the phases. The first effect is taken into account by a distribution parameter, whereas the latter is accounted for by the weighted average drift velocity. Both effects are analyzed and evaluated. The results predicted by the analysis are compared with experimental data obtained for various two-phase flow regimes, with various liquid-gas mixtures in adiabatic, vertical flow over a wide pressure range. Good agreement with experimental data is shown.

Evaluation of Advanced Two-Phase Flow and Combustion Models for Predicting Low Emission Combustors

2000 ◽  
Author(s):  
G. Klose ◽  
R. Schmehl ◽  
R. Meier ◽  
G. Meier ◽  
R. Koch ◽  
...  
Keyword(s):  
Experimental Data ◽  
Two Phase Flow ◽  
Numerical Models ◽  
Computational Method ◽  
Phase Model ◽  
Combustion Model ◽  
Phase Flow ◽  
Two Phase ◽  
Low Emission ◽  
Good Agreement

The development of low emission aero engine combustors strongly depends on the availability of accurate and efficient numerical models. The prediction of the interaction between two-phase flow and chemical combustion is one of the major objectives of the simulation of combustor flows. In this paper, predictions of a swirl stabilized model combustor are compared to experimental data. The computational method is based on an Eulerian two-phase model in conjunction with an Eddy Dissipation (ED) and a presumed-shape-PDF (JPDF) combustion model. The combination of an Eulerian two-phase model with a JPDF combustion model is a novelty. It was found to give good agreement to the experimental data.

Two-Phase Flow Patterns in a Square Micro-Channel

2003 ◽  
Author(s):  
Jian-Fu Zhao ◽  
Bin Li
Keyword(s):  
Experimental Data ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Bond Number ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Scale Modeling ◽  
Order Of Magnitude ◽  
Good Agreement

A new set of experimental data of two-phase air-water flow patterns in a square micro-channel is presented. The channel has a cross-section of 1×1 mm2 and a length of 300 mm. The ranges of the gas and liquid superficial velocities are 0.1–10 m/s and 0.2–7 m/s, respectively. Bubble, bubbleslug transitional, slug, and frothy patterns are observed. The present data are compared with other experimental data reported in the literature, and a good agreement is obtained. It is also compared the present data with those obtained from reduced gravity experiments, in which the Bond number has the same order of magnitude. Some problems associated with the micro-scale modeling of microgravity two-phase flow are also discussed.

Critical Condition of Cavitation Occurrence in Various Liquids

1986 ◽  
Vol 108 (4) ◽  
pp. 428-432 ◽  
Author(s):  
S. Kamiyama ◽  
T. Yamasaki
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Critical Condition ◽  
Reasonable Agreement ◽  
Two Phase Flow ◽  
Cavitation Number ◽  
Experimental Results ◽  
Phase Flow ◽  
Two Phase ◽  
Predicted Values

An experimental study of cavitation occurrence in benzene, kerosene, gasoline, and Freon 12 was conducted using a square-edged orifice. The experimental results of the desinent cavitation number are compared with the calculated values predicted from two-phase flow analogy. The predicted values show reasonable agreement with experimental data for benzene and gasoline but require some modifications for kerosene and Freon 12.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

Random Forces Resulting From Internal Two-Phase Flow on Bends and Tees

2006 ◽  
Author(s):  
E. de Langre ◽  
J. L. Riverin ◽  
M. J. Pettigrew
Keyword(s):  
Two Phase Flow ◽  
Experimental Results ◽  
Time Dependent ◽  
Phase Flow ◽  
Water Mixture ◽  
Dimensionless Form ◽  
Two Phase ◽  
Practical Applications ◽  
Random Forces

The time dependent forces resulting from a two-phase air-water mixture flowing in an elbow and a tee are measured. Their magnitudes as well as their spectral contents are analyzed. Comparison is made with previous experimental results on similar systems. For practical applications a dimensionless form is proposed to relate the characteristics of these forces to the parameters defining the flow and the geometry of the piping.

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