Simulations of cloud condensation droplet nucleation and growth

1989 ◽  
Author(s):  
L. L. Edwards
Keyword(s):  
Nucleation And Growth ◽  
Droplet Nucleation

A Simple and Fast Method for Calculating Properties Across a Condensation Shock

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
V. Babu
Keyword(s):  
Experimental Data ◽  
Steam Turbine ◽  
Simple Procedure ◽  
Nucleation And Growth ◽  
Fast Method ◽  
Algebraic Equations ◽  
Gas Dynamic ◽  
Droplet Nucleation ◽  
Condensation Shock ◽  
Steam Turbine Blade

A simple procedure for calculating the pressure at the onset and termination of condensation shocks that occur in steam nozzles and steam turbine blade passages is presented. In addition, the location of the termination of the condensation shock with reference to the throat location is also predicted. The procedure is based entirely on thermodynamic and gas dynamic considerations, without using a model for droplet nucleation and growth and the nozzle profile. The only input required is the stagnation condition at the inlet to the nozzle. The procedure requires the solution of a system of algebraic equations which can be accomplished quite easily. Calculations have been carried out for several inlet stagnation conditions and the predictions are compared with the available experimental data. The agreement is seen to be reasonable considering the simplicity of the procedure.

Theoretical Treatments of Two-Dimensional Two-Phase Flows of Steam and Comparison with Cascade Measurements

2005 ◽  
Vol 219 (12) ◽  
pp. 1335-1355 ◽  
Author(s):  
F Bakhtar ◽  
A J White ◽  
H Mashmoushy
Keyword(s):  
Numerical Methods ◽  
Nucleation And Growth ◽  
Nucleation Theory ◽  
Two Dimensional ◽  
Wet Steam ◽  
Calculation Methods ◽  
Two Phase ◽  
Droplet Nucleation ◽  
Condensing Flows ◽  
State Path

During the course of expansion of steam in turbines, the state path crosses the saturation line and hence subsequent turbine stages operate with wet steam. These stages have lower thermodynamic efficiencies than those operating in the superheated region, and currently the phenomena contributing to the increased losses are not fully understood. The development of the nucleation theory has opened the way for the study of condensing flows in turbines. As, with the advances in numerical methods, the equations describing droplet nucleation and growth rates can be combined with the field conservation equations and the set treated numerically, which allows the behaviour of complex nucleating and wet steam flows in turbines to be analysed. This paper outlines and reviews wet steam calculation methods and discusses comparisons between numerical and experimental results. For the most part, the comparisons presented are based on work of the authors and their co-workers, but some more recent calculations by other investigators are also included.

Droplet nucleation and growth in orographic clouds in relation to the aerosol population

1999 ◽  
Vol 50 (3-4) ◽  
pp. 289-315 ◽  
Author(s):  
Bengt G Martinsson ◽  
Göran Frank ◽  
Sven-Inge Cederfelt ◽  
Erik Swietlicki ◽  
Olle H Berg ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Droplet Nucleation ◽  
Orographic Clouds

Activated instability of homogeneous droplet nucleation and growth

2008 ◽  
Vol 129 (23) ◽  
pp. 234507 ◽  
Author(s):  
Mark J. Uline ◽  
David S. Corti
Keyword(s):  
Nucleation And Growth ◽  
Droplet Nucleation

MMC-LES modelling of droplet nucleation and growth in turbulent jets

2017 ◽  
Vol 167 ◽  
pp. 204-218 ◽  
Author(s):  
G. Neuber ◽  
A. Kronenburg ◽  
O.T. Stein ◽  
M.J. Cleary
Keyword(s):  
Turbulent Jets ◽  
Nucleation And Growth ◽  
Droplet Nucleation

Failure and Recovery of Droplet Nucleation and Growth on Damaged Nanostructures: A Molecular Dynamics Study

Langmuir ◽  
2020 ◽  
Vol 36 (45) ◽  
pp. 13716-13724
Author(s):  
Guihua Tang ◽  
Dong Niu ◽  
Lin Guo ◽  
Jinliang Xu
Keyword(s):  
Molecular Dynamics ◽  
Nucleation And Growth ◽  
Droplet Nucleation

Droplet Nucleation and Growth in Cryogenic Turboexpanders

2018 ◽  
Author(s):  
Ashish Alex Sam ◽  
Keerthi Raj Kunniyoor ◽  
Jayachandran K. Narayanan ◽  
Arpit Mishra ◽  
Parthasarathi Ghosh
Keyword(s):  
Single Phase ◽  
Flow Analysis ◽  
Droplet Formation ◽  
Nucleation And Growth ◽  
Geometrical Parameters ◽  
Droplet Nucleation ◽  
Ansys Cfx ◽  
Performance Deterioration ◽  
Steady State Simulation ◽  
Droplet Condensation

Cryogenic turboexpanders for nitrogen refrigeration and liquefaction cycles operating near liquefaction conditions are vulnerable to droplet formation. The turboexpander must be devoid of any traces of droplets, as this may cause damage to the blades and also result in performance deterioration. Hence, a multiphase flow analysis was conducted, based on the droplet condensation model in Ansys CFX®, to identify any possible droplet sites and its nature of propagation. A single-phase steady state simulation of the turboexpander was performed initially to identify the regions susceptible to droplet formation, followed by a multiphase analysis to study the flow field behavior and to characterize the droplet nucleation and growth. It has been observed that the low-pressure regions like vortices and wakes are susceptible to sub-cooling and thereby in droplet formation. Also, major geometrical parameters that affect the droplet nucleation have also been identified.

A study of the throughflow of nucleating steam in a turbine stage by a time-marching method

2013 ◽  
Vol 228 (5) ◽  
pp. 932-949 ◽  
Author(s):  
F Bakhtar ◽  
R Mohsin
Keyword(s):  
Nucleation And Growth ◽  
Steam Turbines ◽  
Turbine Stage ◽  
Two Phase ◽  
Droplet Nucleation ◽  
Direct Measurements ◽  
Time Marching ◽  
Phase Mixture ◽  
Marching Method ◽  
General Conservation

In the course of expansion in turbines, steam first supercools and then nucleates to become a two-phase mixture. The fluid then consists of a very large number of extremely small droplets which are carried by and interact with the parent vapour. The formation and subsequent behaviour of the liquid phase cause problems which lower the performance of the wet stages of steam turbines. To treat such flows the general conservation equations governing the whole field are combined with those describing droplet nucleation and growth and the set treated numerically. The article examines the solution of throughflows of nucleating steam in a turbine stage using a time-marching technique. The treatment which is the refinement of an earlier one has been applied to the flow in a turbine stage. Comparisons are presented between the results of theoretical solutions and direct measurements upstream and downstream of the nucleating stage and the agreement obtained is good.

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