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how to incorporate the temperature of fluid in pressure based cavitation model 

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September 23, 2014, 10:51 
how to incorporate the temperature of fluid in pressure based cavitation model

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I want to simulate a cavitation model in a convergingdiverging nozzle.
I use the mixture model where the primary phase is water liquid & the secondary phase is water vapour. the inlet pressure is 248 kpa & the outlet pressure is 101 kpa. the mass flow is 8.78 kg per sec. the temp of the fluid at inlet is 370k. due to heat is not absorbed or released by the fluid throughout the system. we can assume the temp is constant throughout the system, that is 400 k. but I can not incorporate the temp in this model. because there is no option to give the temp in pressure inlet & pressure outlet based cavitation model. So I want to know, how I can incorporate the temp of the fluid in this cavitation model 

September 23, 2014, 11:16 

#2 
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Hi,
I don't understand your question...you are stating that:  we can assume the temp is constant throughout the system, that is 400 k  So I want to know, how I can incorporate the temp of the fluid in this cavitation mode If you want to simulate at constant temperature all you need to do is to specify the fluid properties at that temperature, you don't need to set temperature in fluent; this means you have to set constant density, viscosity, vaporization pressure and surface tension (for Singhal et al model), which are unique values at that operating temperature. 

September 24, 2014, 03:08 

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Quote:
sorry, I give the wrong temp. the right temp is 370k. I get the constant density, viscosity, vaporization pressure and surface tension at this temp for water liquid. but how I can get the density & viscosity of water vapour at this temp? please specify the equation from where I can get the density & viscosity for water vapour at specific temp. 

September 24, 2014, 04:07 

#4 
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You need to calculate saturated steam properties at that vapor pressure/temperature (370 K).
You can use for example this calculator: http://www.peacesoftware.de/einigewe...r_dampf_e.html Input the temperature (370 K) in the box "Calculation of thermodynamic properties of saturated steam". You will have: vaporization pressure: 90535,51 Pa Water: density: 960,59 kg/m3 dynamic viscosity: 0,00029 Pa*s surface tension: 0,05987 N/m (ref. http://www.nist.gov/data/PDFfiles/jpcrd231.pdf) Steam: density: 0,538 kg/m3 dynamic viscosity: 1,216E05 Pa*s 

September 24, 2014, 05:33 

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thank you sir, I got your answer. But I want to know the relation or equation from where I can solve manually the value of the density & viscosity of water vapor at a specific temp


September 24, 2014, 05:34 

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Quote:


September 24, 2014, 05:45 

#7 
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If you treat steam as ideal gas, ideal gas equation for density and Sutherland equation for viscosity (for example).


October 17, 2014, 01:00 

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what is the formula for this case to calculate the turbulent intensity percentage. Last edited by wyldckat; November 1, 2014 at 07:53. Reason: posted few minutes apart 

October 17, 2014, 03:38 

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As I wrote some posts above, the vapor is saturated; so pressure in the ideal gas equation is the vapor pressure at the calculated temperature.
Turbulent intensity is defined as the ratio of the root mean square of the velocity fluctuations, to the mean free stream velocity. 

October 17, 2014, 06:29 

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thank you sir


October 30, 2014, 09:58 

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Is the reynolds number calculation is right ? & can I use this formula for turbulent intensity calculation? I= 0.16 x (Re)^(1/8) 

October 30, 2014, 10:35 

#12 
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If these are the data for inlet Re number is correct.
But I don't think the input data are correct..have you boiling water at venturi exit?? 

October 30, 2014, 13:20 

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so then the input data are correct or not? if the reynolds number calculation is right, then please specify that the above turbulent intensity percentage calculation formula is applicable or not ? Last edited by wyldckat; November 1, 2014 at 07:53. Reason: posted few minutes apart 

October 30, 2014, 13:29 

#14 
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That formula refers to internal duct fully developed flow so if this is the case it is correct.
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October 30, 2014, 14:34 

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October 30, 2014, 14:38 

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Refer to fluent user guide.
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October 31, 2014, 07:00 

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I give all the data as per I told previously. but the calculation show that divergence occurs. which I have to adjust now to converge the solution.


November 3, 2014, 03:41 

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November 6, 2014, 11:31 

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November 11, 2014, 23:36 

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I have done the simulation by taking the water as working fluid. But now I want to do the simulation by taking the diesel fuel as working fluid. So, please tell how I can get the properties of diesel fuel at 300 k & at other temperature. 

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