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Liquid fueled Droplet Evaporation

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Old   December 21, 2006, 17:57
Default Liquid fueled Droplet Evaporation
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Ray
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Hi, Mates

In my case, a single droplet(n-octane) is injected into a stationary domain filled with air. In my view, DPM model is suitable. The initial temperature of the droplet and air defined, is 280 k and 400 k, respectively. The saturated vapor pressure and heat capacity of the droplet are specified as the piecewise polynomial relation with the temperature range, 260-450k. Considering my case, the boudary conditions adopt the velocity B.C. with the velocity, 0 m/s, and the temperature, 400k. But, after running the code, the temperature of the droplet is no variant no matter that any time step is define, and there is of course no evaporation. So, would you give some sugguestion? Thanks a lot.
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Old   December 27, 2006, 05:29
Default Re: Liquid fueled Droplet Evaporation
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Rams
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what is the type of injection you are using & what is the velocity with which the droplect is injected in to still air.

Did u selected the option of interaction with continuos media or not, if not obviously there won't be raise in temp of droplet

In order to make the droplet evaporate, try with increasing the maximum number of steps in DPM
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Old   December 27, 2006, 10:07
Default Re: Liquid fueled Droplet Evaporation
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Ray
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Thanks a lot for your reply. The type of injection is `droplet`. The interaction with continuous media is selected.
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Old   December 27, 2006, 10:15
Default Re: Liquid fueled Droplet Evaporation
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Ray
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Plus, the velocity of the droplet when it is injected is zero.
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Old   December 29, 2006, 04:05
Default Re: Liquid fueled Droplet Evaporation
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Rams
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can i know where is the location of injection point(postion), and what is the domain type,

by fuel injection type i mean, whether surface injection, single injection, group injection or any other type,

normally fuel is injected with certain velocity, try injection with some velocity but if u are injecting fuel with zero velocity then u need to activate gravity effect,to allow for injection with zero velcoity,
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Old   December 29, 2006, 08:09
Default Re: Liquid fueled Droplet Evaporation
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Ray
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Thanks a lot, Rams.

The locus of a single droplet is injected at the center of domain, (0,0). As far as my case is concerned, the heat and species transports are only considered because they are regarded as a sound source, in order to obtain the thermoacoustic effect. Therefore, that the velocity of the surrounding air and the single droplet is zero, is ideal for my case. However, it can not be realized for DPM model, I think. So, the velocity inlet boundary conditions are adopted as the inlet and outlet B.C. Instead of the activated gravity effect, at the beginning, I specify a very small inlet velocity with the magnitude of order e(-30), and once the coupling computation is activated, then the velocity is defined to be zero. I am not sure that this method is right or not. By the way, is there other suitable model for my case?

my email is me2mu@hotmail.com.
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Old   January 2, 2007, 04:25
Default Re: Liquid fueled Droplet Evaporation
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Rams
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first inject the droplet with certain resonable velocity, give some velocity may be 0.5 m/s or so, this will definitely work,

give the upstream pressure in the droplet boundry condition more than the pressure in the domain,

what is the geometry in which u'r are modelling this, is it rectangular field or cylinder or sphere,
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Old   January 2, 2007, 09:06
Default Re: Liquid fueled Droplet Evaporation
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Ray
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Thanks for your suggestion, Rams. In my case, I just concern the heat and mass transfer. So, if the droplet is moving in the domain, it is difficult to analyze the thermoacoustics due to the heat and mass transport between the droplet and the surrounding air. The geometry is a rectangular field, 2-D. I am sorry I cannot catch your point regarding "give the upstream pressure in the droplet boundry condition more than the pressure in the domain". Could you give me some details?

My email: me2mu@hotmail.com. Would you like to contact me by email? I can send a copy of my case to you.

Happy New Year.

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Old   January 3, 2007, 01:36
Default Re: Liquid fueled Droplet Evaporation
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Rams
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Send the case file to me at rams_gk03@yahoo.com,

what are the boundary conditions u have given for the rectangular domain (air),

what i mean by saying give upstream pressure more is that, set the injection pressure higher than the pressure of air in the rectangular domain,

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