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Is it possible to find the droplet size (SMD) of an atomizer as an output of simulati |
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December 30, 2018, 13:58 |
Is it possible to find the droplet size (SMD) of an atomizer as an output of simulati
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#1 |
Senior Member
sluzzer
Join Date: Jul 2014
Posts: 142
Rep Power: 11 |
CFX requires Droplet size as an input to simulate atomizers or spray. It also requires other spray properties line cone angle as input!
In a case where all these parameters are unknown for a given design, is it possible to find it by simulation? |
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December 31, 2018, 05:58 |
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#2 |
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Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,818
Rep Power: 27 |
When using Lagrangian particle tracking, it is possible to use models to include breakup, collision, evapration, etc. In that case, it is possible to predict the droplet diameters. However, the starting diameter and initial cone angle remain as input parameter.
When using Eulerian multiphase modelling, it is possible to calculate the liquid layer inside a nozzle, droplet forming, cone angles, etc., starting from a continuous phase But You need a huge computer and patience, since you require very fine mesh, and extremely small timesteps to capture surface tension effects. Not really feasible. |
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January 3, 2019, 08:14 |
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#3 |
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sluzzer
Join Date: Jul 2014
Posts: 142
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Thanks for the reply Gert-Jan.
Is it a okay to assume that the inlet drop diameter is equivalent to the exit diameter of the orifice or injector? |
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January 3, 2019, 17:49 |
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#4 |
Senior Member
Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,818
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In general no. It depends a lot on the type of nozzle, orifice diameter, geometry, pressure drop, rheology, viscosity, break-up and coalesensce process, etc. Too many parameters determine the droplet size.
Mostly you take a nozzle, perform measurements on droplet size at certain distance from the nozzle and use that as input for a lagrangian particle tracking. If you don't want to do measurements, you have to do Eulerian calcualtions, but that is a hell of a job. Alternatively, rely on specifications of the nozzle supplier, if you use one from the shelf. |
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