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Old   November 10, 2000, 07:52
Default Pulsed Particle Ejection
Ali Khan
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Hi, I am trying to model a Pulsed Particle Ejection. I am a fairly new user of Fluent5.3 or any CFD software and have extremely limited knowledge about it. Therefore if any of you can kindley help achieve what I am trying to do.

I am trying to simulate particle ejection at extremly small pulse rate i.e. 1.0E-03 sec. The ejection area is at extreme temperature and pressure. The ejection is into ambient condition or open space of air at standard conditions.

* What I would like to know is, what model is best suited to my needs.

* Which solver would be best 1) coupled or 2) segregated and if so implicit or explicit function.

I would also like to see the affect of temperature distribution, not only on particles, but also on the tip and the surrounding walls of the ejector nozzle.

Because of the high temperature, is it feassible to assume that there would be radiative heat transfer envolved.

If any of you have done similar work or fairly familiar with the situation please help !!!!!!

Thank you for your time and effort

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Old   November 15, 2000, 04:12
Default Re: Pulsed Particle Ejection
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Thermal spraying is a fairly tricky problem to solve because of steep temperature gradient. But anyway, your problem should be solved in two times:

1) the continuous phase (i.e. your flame or plasma plume if thermal spraying as I guess). For that you should choose a standard k-epsilon model. For solver, take the segregated one with implicit formulation. Your case is solved as steady state. This is allowed if you assume that you have a Newtonian fluid and that the LTE are satisfied. Of course later when you will get more used to CFD you should check wether or not the standard k-E is accurate enough. If not you will have to try the RNG. Regarding radiation, I neglect them. Actually the flow is really highly convection dominated. First you can set a constant temperature for nozzle walls (they are cooled down).

2)Now you are ready to solve your discrete phase model! Define your injection first, to enable the inert-particle definition in the material properties panel.

Have fun, Alice

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