The problems of power number calculation in turbulent rushton turbine stirring tank
I try to simulate stirring tank with rushton turbine. The RNGKE model was selected to simulate the fluid flow in tank. The experimental power number is 0.65. However, the calculated power number is higher than experiment.
Can anyone help me to solve this problems? |
Can anyone help me?
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How power number is greater than experimental data? |
The unbaffled tank with diameter of 0.19 m is simulated by MRF method. The second order upwind is adopted to estimate the face value. The experimental power number is 0.65, while the simulated power number is about 1.3. The top of the tank is a lid, which prevent the presence of vortex. The impeller is rushton turbine with diameter of 0.095 m. The rotating speed is 200 rpm.
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Moreover, I simulated this case with increasing the Swirl Factor of 0.11 (in RNG Options). The simulated tangential velocity and experiment were very similar but the simulated results doesn't smooth (Oscillation). The residual was also oscillation. The residual was higher (about 0.1) than the residual obtained by default Swirl Factor (0.07), (about 0.0001), which give the deviation of tangential velocity at the higher radius.
Can any one help me to solve this problems? |
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see this tutorial: "Modeling Turbulent Flow in a Mixing Tank" |
I do this step as reported in the tutorial. However, these monitors show oscillation. Can anyone suggest me about this problem?
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I hope this help you Be success Jamal |
I'm try as your suggestion but the solution is wrong. However, do you have more suggestion.
Regards B. Eakarach |
Dear Jamal Foroozesh
Please send me your email. Then, i will send my case file to you. Thank in advance |
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turbulence: k-e Realizable impeller wall: moving wall, relative to adjacent cell zone, rotational, speed=0 active gravity pressure: body force weighted momentum , and turbulence equation: first order upwind |
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I am also simulation a CSTR using MRF in openFoam and I need to calculate power number. I do not know how to do this. can anyone help me and ginve an idea? Thanks in advance |
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this is the fluent forum, you'd better to write in openfoam forum; however power number Np is defined by: Np=P/(N^3*Dt^5*rho) P=Absorbed power (W) N=Rotational speed in revolutions per second (rev/s) Dt=Impeller diameter (m) rho=Fluid density (kg/m3) Absorbed power is calculated from simulation, other parameters are known. Daniele |
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http://www.cfd-online.com/Forums/mai...rediction.html but any way thank you very much |
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