scholarly journals A Study on the Mixing Characteristics of Thin Liquid Film Flows over Horizontal Spinning Disk Surface

2016 ◽  
Vol 148 ◽  
pp. 957-962 ◽  
Author(s):  
Mohd Fadhil Majnis ◽  
Nurhazwani Yusoff Azudin ◽  
Syamsul Rizal Abd Shukor ◽  
Abdul Latif Ahmad
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Disk Surface ◽  
Spinning Disk ◽  
Mixing Characteristics ◽  
Film Flows

Hydrodynamics and Heat Transfer in a Liquid Film Flowing Over a Spinning Disk With Specific Wall Topography

2011 ◽  
Author(s):  
Tatiana Gambaryan-Roisman ◽  
Peter Stephan
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Surface Topography ◽  
Thin Liquid Film ◽  
Wave Theory ◽  
Disk Surface ◽  
Negative Influence ◽  
Falling Films ◽  
Spinning Disk ◽  
The Waves

One of the most commonly used methods of liquid atomization is the rotary atomization, or spinning disk atomization. This technique makes use of centrifugal forces to create a thin liquid film spreading radially over a disk. The film flowing along the disk is mostly wavy. The waves have a negative influence on the drop size distribution in the atomization process. It is known that the waves on the falling films can be suppressed by using walls with longitudinal mini grooves. Due to the similarity of the physical mechanisms governing the wave development on falling films and on films flowing over spinning disks, we suggest using grooved disk surfaces for suppressing the waves in spinning disk atomizers. We develop a physico-mathematical model for description of the film dynamics on a spinning disk with wall topography. The model is based on the long-wave theory. It takes into account the hydrodynamic effects governed by liquid viscosity, centrifugal force, inertia and surface tension, as well as the heat transfer between the disk, the liquid, and the ambient gas. The wall surface topography induces a thermocapillary flow in the liquid film leading to heat transfer enhancement and influencing the hydrodynamics. We show that the disk surface topography significantly affects the film hydrodynamics.

Effect of Hydraulic Jump on Hydrodynamics and Heat Transfer in a Thin Liquid Film Flowing Over a Rotating Disk Analyzed by Integral Method

2006 ◽  
Vol 129 (5) ◽  
pp. 657-663 ◽  
Author(s):  
S. Basu ◽  
B. M. Cetegen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Hydraulic Jump ◽  
Thin Liquid Film ◽  
Rotating Disk ◽  
Disk Surface ◽  
Constant Heat Flux ◽  
Heat Transfer Analysis ◽  
Scaling Analysis

Flow and heat transfer in a liquid film flowing over the surface of a rotating disk was analyzed by integral technique. The integral analysis includes the prediction of the hydraulic jump and its effects on heat transfer. The results of this analysis are compared to the earlier results that did not include this effect. At low inlet Reynolds numbers and high Rossby numbers, corresponding to low film inertia and low rotation rates, respectively, a hydraulic jump appears on the disk surface. The location of the jump and the liquid film height at this location are predicted. A scaling analysis of the equations governing the film thickness provided a semi-empirical expression for these quantities that was found to be in very good agreement with numerical results. Heat transfer analysis shows that the Nusselt numbers for both constant disk surface temperature and constant disk surface heat flux boundary conditions are lowered in the vicinity of the hydraulic jump due to the thickened liquid film. This effect can be more pronounced for the constant heat flux case depending on the location of the hydraulic jump. The Nusselt number exhibits a turning point at the jump location and can have higher values downstream of the hydraulic jump compared to those obtained from the analysis that does not include the gravitational effects.

scholarly journals Analysis of Hydrodynamics and Heat Transfer in a Thin Liquid Film Flowing Over a Rotating Disk by the Integral Method

2005 ◽  
Vol 128 (3) ◽  
pp. 217-225 ◽  
Author(s):  
S. Basu ◽  
B. M. Cetegen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Rotating Disk ◽  
Disk Surface ◽  
Experimental Results ◽  
Rotation Rates

An integral analysis of hydrodynamics and heat transfer in a thin liquid film flowing over a rotating disk surface is presented for both constant temperature and constant heat flux boundary conditions. The model is found to capture the correct trends of the liquid film thickness variation over the disk surface and compare reasonably well with experimental results over the range of Reynolds and Rossby numbers covering both inertia and rotation dominated regimes. Nusselt number variation over the disk surface shows two types of behavior. At low rotation rates, the Nusselt number exhibits a radial decay with Nusselt number magnitudes increasing with higher inlet Reynolds number for both constant wall temperature and heat flux cases. At high rotation rates, the Nusselt number profiles exhibit a peak whose location advances radially outward with increasing film Reynolds number or inertia. The results also compare favorably with the full numerical simulation results from an earlier study as well as with the reported experimental results.

CFD Modeling of a Thin Liquid Film Flow over Horizontal Spinning Disk

2014 ◽  
Vol 625 ◽  
pp. 517-521
Author(s):  
Nurhazwani Yusoff Azudin ◽  
Mohd Fadhil Majnis ◽  
Ahmad Abdul Latif ◽  
Syamsul Rizal Abd Shukor
Keyword(s):  
Liquid Film ◽  
Cfd Simulation ◽  
Film Flow ◽  
Mechanistic Model ◽  
Thin Liquid Film ◽  
Process Intensification ◽  
Cfd Modeling ◽  
Spinning Disk ◽  
Vof Model ◽  
Liquid Film Flow

A thin liquid film flow over horizontal spinning disk under influence of centrifugal field is one of the implementation and method in process intensification. Hydrodynamic studies and development of mechanistic model is desired to describe this film flow behaviours. CFD software package, Fluent® 6.3 was used to simulate a multiphase volume of fraction (VOF) model of this flow. Then, experiments were carried out in a spinning disk test rig with variable speed of spinning and results were compared with CFD simulation. The result obtained have showed that CFD model for thin liquid film thickness was in satisfactory agreement with the experimental results with R2 = 0.841 to 0.857.

Transport to a Chemically Active Thin Liquid Film Over a Spinning Disk

1998 ◽  
Vol 120 (4) ◽  
pp. 293-298 ◽  
Author(s):  
M. M. Rahman
Keyword(s):  
Reynolds Number ◽  
Liquid Film ◽  
Reaction Rate ◽  
Separation Of Variables ◽  
Thin Liquid Film ◽  
Transport Processes ◽  
Space Environment ◽  
Species Concentration ◽  
Ekman Number ◽  
Spinning Disk

An analytical solution for the process of mass transfer from a spinning disk to a chemically active thin liquid film flowing over the disk is presented. By analogy, the results are also applicable to heat transfer to the film with temperature-dependent heat generation. The process is modeled by establishing equations for the conservation of mass, momentum, and species concentration, and solving them analytically. The partial differential equation for species concentration is solved using the separation of variables technique along with the application of the Duhamel’s theorem. Tables for eigenvalues and eigenfunctions are presented for a number of reaction rate constants. A parametric study was performed using Reynolds number, Ekman number, and chemical reaction rate as parameters. It was found that Sherwood number increases with Reynolds number (flow rate) as well as inverse of Ekman number (rate of rotation). These fundamental results will be useful to design advanced energy transport processes for a low-gravity space environment.

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