Numerical solution of two-phase flow of wet steam with a given droplet size distribution function

2013 ◽  
Author(s):  
J. Halama
Keyword(s):  
Distribution Function ◽  
Numerical Solution ◽  
Size Distribution ◽  
Droplet Size ◽  
Two Phase Flow ◽  
Droplet Size Distribution ◽  
Size Distribution Function ◽  
Phase Flow ◽  
Wet Steam ◽  
Two Phase

Thermal-Hydraulics of OC-OTEC Spout Flash Evaporators

1992 ◽  
Vol 114 (3) ◽  
pp. 187-196 ◽  
Author(s):  
S. M. Ghiaasiaan
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Two Phase Flow ◽  
Mechanistic Model ◽  
Droplet Size Distribution ◽  
Momentum Conservation ◽  
Phase Flow ◽  
Two Phase ◽  
Conservation Equations ◽  
Size Groups

A mechanistic model was developed for the thermal-hydraulic processes in the spout flash evaporator of an OC-OTEC plant. Nonequilibrium, two-fluid, conservation equations were solved for the two-phase flow in the spout, accounting for evaporation at the gas-liquid interface, and using a two-phase flow regime map consisting of bubbly, churn-turbulent and dispersed droplet flow patterns. Solution of the two-phase conservation equations provided the flow conditions at the spout exit, which were used in modeling the fluid mechanics and heat transfer in the evaporator, where the liquid was assumed to shatter into a spray with a log-normal size distribution. Droplet size distribution was approximated by using 30 discrete droplet size groups. Droplet momentum conservation equations were numerically solved to obtain the residence time of various droplet size groups in the evaporator. Evaporative cooling of droplets was modeled by solving the 1-D heat conduction equation in spheres, and accounting for droplet internal circulation by an empirical thermal diffusivity multiplier. The model was shown to favorably predict the available single-spout experimental data.

scholarly journals CFD Simulation of Polydispersed Bubbly Two-Phase Flow around an Obstacle

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
E. Krepper ◽  
P. Ruyer ◽  
M. Beyer ◽  
D. Lucas ◽  
H.-M. Prasser ◽  
...  
Keyword(s):  
Size Distribution ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Size Distribution Function ◽  
Phase Flow ◽  
Two Phase ◽  
Ansys Cfx ◽  
Two Fluid Model ◽  
Drag And Lift

This paper concerns the model of a polydispersed bubble population in the frame of an ensemble averaged two-phase flow formulation. The ability of the moment density approach to represent bubble population size distribution within a multi-dimensional CFD code based on the two-fluid model is studied. Two different methods describing the polydispersion are presented: (i) a moment density method, developed at IRSN, to model the bubble size distribution function and (ii) a population balance method considering several different velocity fields of the gaseous phase. The first method is implemented in the Neptune_CFD code, whereas the second method is implemented in the CFD code ANSYS/CFX. Both methods consider coalescence and breakup phenomena and momentum interphase transfers related to drag and lift forces. Air-water bubbly flows in a vertical pipe with obstacle of the TOPFLOW experiments series performed at FZD are then used as simulations test cases. The numerical results, obtained with Neptune_CFD and with ANSYS/CFX, allow attesting the validity of the approaches. Perspectives concerning the improvement of the models, their validation, as well as the extension of their applicability range are discussed.

On the Theoretical Prediction of Fuel Droplet Size Distribution in Nonreactive Diesel Sprays

2001 ◽  
Vol 124 (1) ◽  
pp. 182-185 ◽  
Author(s):  
Jianming Cao
Keyword(s):  
Distribution Function ◽  
Size Distribution ◽  
Droplet Size ◽  
Cross Sections ◽  
Droplet Size Distribution ◽  
Size Distribution Function ◽  
Fuel Droplet ◽  
Diesel Sprays ◽  
Mean Diameter ◽  
Higher Temperature

Droplet size distribution function and mean diameter formulas are derived using information theory. The effects of fuel droplet evaporation and coalescence within combustion chamber on the droplet size are emphasized in nonreactive diesel sprays. The size distribution function expressions at various spray axial cross sections are also formulated. The computations are compared with experimental data and KIVA-II code. A good agreement is obtained between numerical and experimental results. Droplet size distribution and mean diameter at various locations from injector exit and at various temperature conditions are predicted. The decreases of droplet number and variations of mean diameter are computed at downstream and higher temperature.

Generation and Size Distribution of Droplet in Annular Two-Phase Flow

1983 ◽  
Vol 105 (2) ◽  
pp. 230-238 ◽  
Author(s):  
Isao Kataoka ◽  
Mamoru Ishii ◽  
Kaichiro Mishima
Keyword(s):  
Experimental Data ◽  
Size Distribution ◽  
Droplet Size ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Mechanistic Modeling ◽  
Dominant Factor ◽  
Phase Flow ◽  
Two Phase ◽  
Detailed Model

The mean droplet size and size distribution are important for detailed mechanistic modeling of annular two-phase flow. A large number of experimental data indicate that the standard Weber number criterion based on the relative velocity between droplets and gas flow predicts far too large droplet sizes. Therefore, it was postulated that the majority of the droplets were generated at the time of entrainment and the size distribution was the direct reflection of the droplet entrainment mechanism based on roll-wave shearing off. A detailed model of the droplet size in annular flow was then developed based on the above assumption. The correlations for the volume mean diameter as well as the size distribution were obtained in collaboration with a large number of experimental data. A comparison with experimental data indicated that indeed the postulated mechanism has been the dominant factor in determining the drop size. Furthermore, a large number of data can be successfully correlated by the present model. These correlations can supply accurate information on droplet size in annular flow which has not been available previously.

scholarly journals Numerical simulation of high-pressure gas atomization of two-phase flow: Effect of gas pressure on droplet size distribution

2019 ◽  
Vol 30 (11) ◽  
pp. 2726-2732 ◽  
Author(s):  
Kalpana Hanthanan Arachchilage ◽  
Majid Haghshenas ◽  
Sharon Park ◽  
Le Zhou ◽  
Yongho Sohn ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Gas Pressure ◽  
Phase Flow ◽  
Gas Atomization ◽  
Two Phase ◽  
Flow Effect
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