A Probability Analysis of Atomization Rate for Fully Developed Annular Flow in Vertical Pipes

2017 ◽  
Author(s):  
Ri Zhang ◽  
Sheng Dong
Keyword(s):  
Annular Flow ◽  
Probability Model ◽  
Droplet Breakup ◽  
Probability Analysis ◽  
Breakup Process ◽  
Deposition Rates ◽  
Important Intermediate ◽  
Basic Equations ◽  
Random States ◽  
Development And Evolution

The phase distributions and mechanical properties of annular flow are constantly fluctuating, so they can be regarded as random states. The probability analysis of annular flow is an appropriate method to research the formation, development and evolution of the flow pattern. In the present work, the atomization and deposition rates of fully developed annular flow are investigated in detail by the method of a probability analysis. First, the basic equations of the probability model are applied to solve some important intermediate parameters of annular flow. Second, the atomization and deposition rates of any size droplets are closely related to the probabilities of droplet generation and disappearance. Third, the interchange rate of the whole liquid phase can be obtained by summing the generation and disappearance probabilities of arbitrary size droplets. The predictions of atomization rate are well verified by comparing with the experimental date of 71 cases from three sets of tests. It is demonstrated that the probability model can accurately calculate the atomization rate of the fully developed annular flow for most cases. The predicted deviation for some cases may be caused by the neglect of droplet breakup process. Furthermore, the effects on the atomization rate of seven parameters of annular flow are discussed in detail.

Analysis of the Interchange Rate and Pressure Gradient of Annular Flow Based on a Probability Model

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Ri Zhang ◽  
Feng Zhang ◽  
Sheng Dong
Keyword(s):  
Pressure Gradient ◽  
Annular Flow ◽  
Phase Distribution ◽  
Probability Model ◽  
Interfacial Shear Stress ◽  
Flow Rates ◽  
Liquid Phases ◽  
Deposition Processes ◽  
Basic Equations ◽  
Relationship Of

The phase distribution and mechanical properties of annular flow have obvious, random characteristics because of the influence of turbulence. Thus, probability analysis is a suitable method for the study of annular flow. In the present work, the interchange rate and pressure gradient of fully developed annular flow are investigated in detail based on a probability model. The probability model tracks the atomization and deposition processes of a single particle to analyze the momentum and mass exchange between the gas and liquid phases. The interchange rate can be calculated by summing the generation or disappearance probability of droplets with different sizes. The pressure gradient can be obtained by solving the basic equations of the annular flow, which contains an improved relationship of interfacial shear stress. The predictions of the interchange rate and pressure gradient are well verified by comparison with experimental data available in the literature. Furthermore, the effects of the gas and liquid flow rates on the interchange rate and pressure gradient are discussed in detail.

AN ASSESSMENT OF THE CORRELATIONS FOR ENTRAINMENT AND DEPOSITION RATES IN ANNULAR FLOW FOR DRYOUT PREDICTION

2016 ◽  
Vol 28 (2) ◽  
pp. 99-133 ◽  
Author(s):  
Arnab Dasgupta ◽  
D.K. Chandraker ◽  
S. P. Walker ◽  
P. K. Vijayan
Keyword(s):  
Annular Flow ◽  
Deposition Rates

A probability model of predicting the sand erosion in elbows for annular flow

Wear ◽  
2019 ◽  
Vol 422-423 ◽  
pp. 167-179 ◽  
Author(s):  
Rong Kang ◽  
Haixiao Liu
Keyword(s):  
Annular Flow ◽  
Probability Model ◽  
Sand Erosion

Numerical Investigation of an Efficient Method (T-Junction With Valve) for Producing Unequal-Sized Droplets in Micro- and Nano-Fluidic Systems

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Ahmad Bedram ◽  
Amir Ebrahim Darabi ◽  
Ali Moosavi ◽  
Siamak Kazemzade Hannani
Keyword(s):  
Pressure Drop ◽  
Efficient Method ◽  
Capillary Number ◽  
Numerical Scheme ◽  
Volume Ratio ◽  
Droplet Breakup ◽  
Breakup Process ◽  
Breakup Length ◽  
Breakup Time ◽  
Arbitrary Volume

We investigate an efficient method (T-junction with valve) to produce nonuniform droplets in micro- and nano-fluidic systems. The method relies on breakup of droplets in a T-junction with a valve in one of the minor branches. The system can be simply adjusted to generate droplets with an arbitrary volume ratio and does not suffer from the problems involved through applying the available methods for producing unequal droplets. A volume of fluid (VOF) based numerical scheme is used to study the method. Our results reveal that by decreasing the capillary number, smaller droplets can be produced in the branch with valve. Also, we find that the droplet breakup time is independent of the valve ratio and decreases with the increase of the capillary number. Also, the results indicate that the whole breakup length does not depend on the valve ratio. The whole breakup length decreases with the decrease of the capillary number at the microscales, but it is independent of the capillary number at the nanoscales. In the breakup process, if the tunnel forms the pressure drop does not depend on the valve ratio. Otherwise, the pressure drop reduces linearly by increasing the valve ratio.

A Probability Model for Fully Developed Annular Flow in Vertical Pipes: Film Thickness, Interfacial Shear Stress, and Droplet Size Distribution

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Ri Zhang ◽  
Haixiao Liu ◽  
Sheng Dong ◽  
Mingyang Liu
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
Size Distribution ◽  
Droplet Size ◽  
Annular Flow ◽  
Probability Model ◽  
Interfacial Shear Stress ◽  
Droplet Size Distribution ◽  
Interfacial Shear ◽  
Characteristic Parameters

The movement and distribution of each phase in annular flow can be considered as random events at a microscopic level. Hence, a probability analysis is appropriate to estimate the morphological features and mechanical characteristics of annular flow from a macroscopic scale. In the present work, three characteristic parameters including the film thickness, interfacial shear stress, and characteristic droplet size are predicted by a probability model as the statistical results of abundant samples. The film thickness can be directly calculated as one of the solutions to the basic equations of annular flow. The interfacial shear stress is estimated as a combination of the frictional and dragging components. The droplet size distribution is obtained using a method of undetermined coefficients. These characteristic parameters are well verified by comparing with the experimental data available in the literature. It is demonstrated that the probability model can accurately calculate the film thickness and maximum droplet size, but the predictions of the interfacial shear stress and mean droplet size are relatively coarse. Furthermore, the effects on the film thickness and Sauter mean diameter of other parameters are discussed in detail. Finally, some important phenomena observed in experiments are interpreted by the probability model.

Ferrofluid droplet breakup process and neck evolution under steady and pulse-width modulated magnetic fields

2021 ◽  
pp. 117536
Author(s):  
Mohamad Ali Bijarchi ◽  
Amirhossein Favakeh ◽  
Kaivan Mohammadi ◽  
Ali Akbari ◽  
Mohammad Behshad Shafii
Keyword(s):  
Magnetic Fields ◽  
Pulse Width ◽  
Droplet Breakup ◽  
Breakup Process ◽  
Pulse Width Modulated

scholarly journals Kinematics of the viscous filament during the droplet breakup in air

2021 ◽  
Author(s):  
Diana Broboana ◽  
Ana-Maria Bratu ◽  
Istvan Magos ◽  
Claudiu Patrascu ◽  
Corneliu Balan
Keyword(s):  
Experimental Data ◽  
Transition Region ◽  
Velocity Gradient ◽  
Complex Fluids ◽  
Droplet Breakup ◽  
Relevant Parameter ◽  
Interfacial Rheology ◽  
Breakup Process ◽  
Relative Time ◽  
Viscous Forces

Abstract The dripping regime in the vicinity of droplet breakup is analyzed concerning the evolution of the filament’s neck and its corresponding thinning velocity. Three flow regimes are observed as the relative time decreases: (i) a monotonous increase of the neck’s thinning velocity, where inertia and capillarity are balanced, (ii) a transition region characterized by the equilibrium between inertia, capillarity, and viscous forces, where the thinning velocity varies non-monotonically with the relative time and (iii) the final pinch-off regime, where velocity decreases or oscillates around a constant value. Based on the correlation between experimental data and numerics, the distribution of the zeta - coefficient (defined as the non-dimensional second invariant of the velocity gradient) on the droplet’s profile is used to quantify the ratio between elongation and rotation of the fluid at the interface. The regions dominated by extension, where pure elongation is located at zeta = 1 , are determined. One main result of this study is the confirmation that distribution of the zeta - coefficient is a relevant parameter to analyze and to quantify the breakup process. This result has the potential of developing novel techniques and more precise procedures in determining the interfacial rheology of viscous and complex fluids.

PROBABILITY ANALYSIS OF FLUCTUATIONS OF GRASSHOPPER POPULATIONS IN SASKATCHEWAN

1988 ◽  
Vol 120 (12) ◽  
pp. 1063-1070 ◽  
Author(s):  
M.K. Mukerji ◽  
H.N. Hayhoe
Keyword(s):  
Markov Chain ◽  
Probability Model ◽  
Crop Protection ◽  
Probability Analysis ◽  
Potential Usefulness ◽  
Rural Municipality ◽  
Transitional Probabilities ◽  
Expected Duration

AbstractDistribution of grasshopper populations was examined on a rural municipality (RM) basis over a 44-year period in Saskatchewan. A two-state Markov chain probability model was used to describe the transitional probabilities from high or low populations for different time steps. The analysis showed significant persistence of grasshopper populations in particular locations but the degree of persistence varied between RMs. The probability model was used to determine the expected duration of outbreaks or recessions. The potential usefulness of estimates of the expected duration of an outbreak is discussed in relation to crop protection.

Droplet entrainment and deposition rates in a horizontal annular flow for SPACE code

2018 ◽  
Vol 109 ◽  
pp. 45-52 ◽  
Author(s):  
Byeonggeon Bae ◽  
Taeho Kim ◽  
Jaejun Jeong ◽  
Kyungdoo Kim ◽  
Byongjo Yun
Keyword(s):  
Annular Flow ◽  
Deposition Rates ◽  
Droplet Entrainment
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