Measurement Techniques in the Two-Phase Flow Region of the Air-Sea Interface Layer

1978 ◽  
pp. 407-416
Author(s):  
François Resch
Keyword(s):  
Two Phase Flow ◽  
Measurement Techniques ◽  
Flow Region ◽  
Interface Layer ◽  
Phase Flow ◽  
Two Phase

scholarly journals Behavior of a Horizontal Gas-Liquid Two-Phase Flow under Microgravity. Flow Pattern and Film Construction in Annular Flow Region.

1992 ◽  
Vol 58 (555) ◽  
pp. 3286-3291 ◽  
Author(s):  
Terushige FUJII ◽  
Takeshi NAKAZAWA ◽  
Hiroyuki YAMADA ◽  
Osamu MURAGISHI ◽  
Nobuyuki TAKENAKA ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Region ◽  
Phase Flow ◽  
Two Phase

scholarly journals Overview of Void Fraction Measurement Techniques, Databases and Correlations for Two-Phase Flow in Small Diameter Channels

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 216
Author(s):  
Álvaro Roberto Gardenghi ◽  
Erivelto dos Santos Filho ◽  
Daniel Gregório Chagas ◽  
Guilherme Scagnolatto ◽  
Rodrigo Monteiro Oliveira ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Measurement Techniques ◽  
Small Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Diameter ◽  
Experimental Database ◽  
Absolute Relative Error ◽  
Fraction Measurement

Void fraction is one of the most important parameters for the modeling and characterization of two-phase flows. This manuscript presents an overview of void fraction measurement techniques, experimental databases and correlations, in the context of microchannel two-phase flow applications. Void fraction measurement techniques were reviewed and the most suitable techniques for microscale measurements were identified along its main characteristics. An updated void fraction experimental database for small channel diameter was obtained including micro and macrochannel two-phase flow data points. These data have channel diameter ranging from 0.5 to 13.84 mm, horizontal and vertical directions, and fluids such as air-water, R410a, R404a, R134a, R290, R12 and R22 for both diabatic and adiabatic conditions. New published void fraction correlations as well high cited ones were evaluated and compared to this small-diameter void fraction database in order to quantify the prediction error of them. Moreover, a new drift flux correlation for microchannels was also developed, showing that further improvement of available correlations is still possible. The new correlation was able to predict the microchannel database with mean absolute relative error of 9.8%, for 6% of relative improvement compared to the second-best ranked correlation for small diameter channels.

Effect of two-phase flow on transmission torque of oil film at high rotational speeds

2018 ◽  
Vol 70 (8) ◽  
pp. 1367-1373 ◽  
Author(s):  
Fangwei Xie ◽  
Xudong Zheng ◽  
Yaowen Tong ◽  
Bing Zhang ◽  
Xinjian Guo ◽  
...  
Keyword(s):  
Flow Regime ◽  
Rotational Speed ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Flow Region ◽  
Phase Flow ◽  
Field Variation ◽  
Two Phase ◽  
Content Type ◽  
Oil Film

Purpose The purpose of this paper is to study the working characteristics of hydro-viscous clutch at high rotational speeds and obtain the trend of flow field variation of oil film. Design/methodology/approach The FLUENT simulation model of the oil film between the friction disks is built. The effect of variation of working parameters such as input rotational speed, oil flow rate and film thickness on two-phase flow regime and transmission torque is studied by using the volume of fluid model. Findings The results show that the higher the rotational speed, the severer the cavitation is. In addition, the two-phase flow region makes the coverage of oil film over the friction pairs’ surface reduce, which results in a decrease in transmission torque for the hydro-viscous clutch. Originality/value These simulation results are of interest for the study of hydro-viscous drive and its applications. This study can also provide a theoretical basis for power transmission mechanism of oil film by considering the existence of a two-phase flow regime consisting of oil and air.

Experimental Measurements and Numerical Simulations of Two-Phase Stratified, Wavy and Slug Flow in a Narrow Rectangular Channel

2005 ◽  
Author(s):  
Steven P. O’Halloran ◽  
B. Terry Beck ◽  
Mohammad H. Hosni ◽  
Steven J. Eckels
Keyword(s):  
Numerical Simulations ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Measurement Techniques ◽  
Narrow Channel ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Two Phase ◽  
Two Fluids

Flow pattern transitions in two-phase flow are important phenomena for many different types of engineering applications, including heat exchangers. While two-phase flow is not understood as well as single-phase flow, advancements in both measurement techniques and numerical simulations are helping to increase the understanding of two-phase flow. In this paper, stratified/wavy flow is investigated, along with the transition from wavy to slug flow. For the experimental setup, a narrow channel with a length of 600 mm, height of 40 mm, and a width of 15 mm was fabricated using clear acrylic plastic, and water and air were the two fluids used for testing. The water in the channel was initially at rest, and the transition in flow patterns was created by increasing the velocity of air flowing over the water surface. Particle image velocimetry (PIV) was used to measure the velocity of the flow for stratified and wavy flow conditions, and also the velocity at the onset of slug flow. Along with the experimental measurements, computational fluid dynamics (CFD) simulations were conducted on a similar geometry using the volume of fluid (VOF) two-phase model. A commercial CFD software package was used for the simulations, and comparisons were made between the experimental measurements and numerical results. Favorable agreement was found between the experimental measurements and the numerical simulations. In particular, the transition from wavy to slug flow compared well to previously developed two-phase flow transition models, including the slug transition developed by Taitel and Dukler.

Void Fraction Measurements for Air-Water Pipe Flows Using Quick-Closing Valves and Wire-Mesh Sensors

2018 ◽  
Author(s):  
Étienne Lessard ◽  
Jun Yang
Keyword(s):  
Void Fraction ◽  
Test Section ◽  
Two Phase Flow ◽  
Measurement Techniques ◽  
Wire Mesh ◽  
Axial Distance ◽  
Phase Flow ◽  
Flow Conditions ◽  
Flow Loop ◽  
Two Phase

In support of a header/feeder phenomena study, an adiabatic, near-atmospheric, air-water flow loop was commissioned simulating a single feeder of a Pressurized Heavy Water Reactor’s primary heat transport system under a postulated Loss of Coolant Accident scenario. An extensive database in representative two-phase flow conditions was collected, 750 tests in total, in order to create a two-phase flow map to be used in the more complex geometries such as header/feeder systems. The flow loop consists of two vertical test sections, for upwards and downwards flow, and one horizontal test section, each with an inner diameter of 32 mm and at least 120 diameters in length. Superficial velocities extended up to 6 m/s for the water and 10 m/s for the air. Void fraction was measured by means of quick-closing valves and a pair of wire-mesh sensors (WMS) in each test section. Two-phase repeatability tests showed that the liquid and gas superficial velocities varied by 1.1% and 0.6% at reference conditions of 2.0 and 2.8 m/s, respectively. The corresponding void fraction measurements varied for the quick-closing valves by at most 6.8%, which indicates a low sensitivity to the closure time of the valves and an appropriate axial distance between them, and 2.3% for the WMS. For both measurement techniques, the largest variations occurred in the vertical downwards test section. For the formal two-phase tests, over 600 distinct flow conditions were performed. The results showed that the two measurement techniques agreed within 5% at high void fractions and low liquid flow rates in vertical flow. For all other cases corresponding to the transitional or dispersed bubbly flow regime, the WMS over-estimated the void fraction by a consistent bias. An empirical correction is proposed, with a root-mean-square error of 6.6% across all tests. The void fraction map resulting from this database provides validation for the WMS measurements, a quantitative assessment of its uncertainty and range of applicability, and will be used as a reference in future tests under similar scale and flow conditions.

Analysis of Two-Phase Flow in Cryogenic Damper Seals—Part I: Theoretical Model

1998 ◽  
Vol 120 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Grigory L. Arauz ◽  
Luis San Andre´s
Keyword(s):  
Two Phase Flow ◽  
Flow Region ◽  
Forced Response ◽  
Dynamic Force ◽  
Phase Flow ◽  
Two Phase ◽  
Fluid Damper ◽  
Theoretical Predictions ◽  
Saturated Mixture ◽  
Liquid Vapor

Cryogenic fluid damper seals operating close to the liquid-vapor region (near the critical point or slightly sub-cooled) are likely to develop a two-phase flow region which affects the seal performance and reliability. An all-liquid, liquid-vapor, and all-vapor, i.e., a “continuous vaporization” bulk flow model is presented for prediction of the seal dynamic forced response. Continuity, momentum, and energy (enthalpy) transport equations govern the two-phase flow of a homogeneous saturated mixture in thermodynamic equilibrium. Static and dynamic force performance characteristics for the seal are obtained from a perturbation analysis of the governing equations. Theoretical predictions and comparisons to experimental measurements in a liquid and gaseous nitrogen seal are presented in Part II. The effects of two-phase flow regimes on the dynamic force coefficients and stability of an oxygen damper seal are also discussed.

Liquid Jet Impingement on a Free Liquid Surface: PIV Study of the Turbulent Bubbly Two-Phase Flow

2010 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Flow Field ◽  
Two Phase Flow ◽  
Jet Impingement ◽  
Flow Region ◽  
Air Entrainment ◽  
Continuous Phase ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Field Characteristics ◽  
Inflow Conditions

The turbulent two-phase flow arising from the normal impingement of a round free-surface water jet on a horizontal air-water interface was experimentally studied. Due to the weakly viscous nature of the flow system under consideration, external perturbations or small variations in jet inflow conditions can lead to drastically different flow field characteristics under seemingly similar test conditions. In the current study, a fully developed turbulent jet, exiting a long pipe, ensured properly characterized inflow conditions. The study considered two jet inflow conditions; one entrained air and created a bubbly two-phase flow field while the other did not. Particle image velocimetry (PIV) was used to characterize the flow field beneath the interface, with and without air entrainment, for various nozzle-to-interface separation distances. Turbulent velocity fields of the continuous-phase and dispersed-phase were simultaneously measured in the developing flow region and presented using Reynolds decomposition into mean and fluctuating components. The mean and RMS velocities of the two-phase flow field were compared with velocity measurements obtained under single-phase conditions.

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