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September 6, 2013, 05:38 
Simulation flow through Propeller by SRFSimpleFoam

#1 
New Member
DANG QUOC BAO
Join Date: Apr 2013
Posts: 12
Rep Power: 5 
Dear All
I have problem with simulation flow over propeller by OpenFoam. I used OpenFoam with solver SRFSimpleFoam. I set intinial conditions and parameters follow tutorial Mixer but i dont have result or value of P very big so i don what were the reasons?. I used turbulence model Komega SST. I dont know calculate force and torque of Propeller. Please help me solver this problem? I very confused... Thank you very much ..... epsilon FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object epsilon; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [ 0 2 3 0 0 0 0 ]; internalField uniform 2.546; boundaryField { inlet { type fixedValue; value uniform 2.546; } outlet { type zeroGradient; } blade { type epsilonWallFunction; U Urel; value uniform 2.546; } cylinder { type zeroGradient; } K } FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object k; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [ 0 2 2 0 0 0 0 ]; internalField uniform 0.84375; boundaryField { inlet { type fixedValue; value uniform 0.84375; } outlet { type zeroGradient; } blade { type kqRWallFunction; value uniform 0.84375; } cylinder { type zeroGradient; } } OMEGA FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object omega; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [ 0 0 1 0 0 0 0 ]; internalField uniform 3.014; boundaryField { inlet { type fixedValue; value uniform 3.014; } outlet { type zeroGradient; } blade { type omegaWallFunction; U Urel; value uniform 3.014; } cylinder { type zeroGradient; } } // ************************************************** *********************** // FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [ 0 2 2 0 0 0 0 ]; internalField uniform 0; boundaryField { inlet { type zeroGradient; } outlet { type fixedValue; value uniform 0; } blade { type zeroGradient; } cylinder { type zeroGradient; } } UREL FoamFile { version 2.0; format ascii; class volVectorField; location "0"; object Urel; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [ 0 1 1 0 0 0 0 ]; internalField uniform ( 0 0 0 ); boundaryField { inlet { type SRFVelocity; inletValue uniform ( 0 0 15 ); relative no; value uniform ( 0 0 0 ); } outlet { type zeroGradient; } blade { type fixedValue; value uniform ( 0 0 0 ); } cylinder { type SRFVelocity; inletValue uniform ( 0 0 0 ); relative no; value uniform ( 0 0 0 ); } } // ************************************************** *********************** //************************************************** *********** // FoamFile { version 2.0; format ascii; class dictionary; location "constant"; object SRFProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // SRFModel rpm; axis ( 0 0 1 ); rpmCoeffs { rpm 5000; } 

September 7, 2013, 07:28 

#2 
Senior Member

Hi,
Actually your questions are not clear, however I will try my best. Have a look of the following thread for calculating initial value for k and epsilon. Help with k epsilon values of turbulence To get the forces and torque, just copy and paste the following function underneath your controlDict file. functions ( forces { type forces; functionObjectLibs ("libforces.so"); outputControl timeStep; outputInterval 10; patches (fan); // pname p; // Uname U; rhoName rhoInf; log true; rhoInf 1.20; CofR (0 0 0); } ) Thanks, Sivakumar Last edited by sivakumar; September 9, 2013 at 03:30. 

September 8, 2013, 11:39 

#3 
New Member
DANG QUOC BAO
Join Date: Apr 2013
Posts: 12
Rep Power: 5 
Dear Sivakumar
I am grateful to you for your reply. I will describe my problem. I have propeller with diameter 9 inchs and picth 6 inch (Master propeller 9x6 for UAV). I had done experiment in windtunnel with this propeller and determined their thrust and torque. Now, my problem is how determine thrust and torque of propeller by numerrical method using OpenFOAM. I have 3D model of propeller and generated mesh. Parameter of propeller: inlet velocity (speed flight): 10  15 m/s; RPM of Propeller 4000  8000 RPM; chord of propeller 0.75R = 17 mm. I used tool estimate yplus of CFD online and calculate yplus. My mesh model has the first node from surface blade yplus = 20. For simulation flow through this propeller, i used solver SRFSimpleFoam version 2.1.0 and turbulence model Komega SST (flow steady and incompressible). I set value of boundary conditions k, omega, nut, p, Urel as in last post (please see last post). I calculate 1000 time but I have result different pressure very large and force very large (> 10000 N). I think wrong because force and pressyre very large. Would you mind help me solver this proplem? 1) With my problem, I used solver SRFSimpleFoam is right or wrong? Which is solver of OpenFoam i can calculate thrust and torque of propeller (steady and incompressible) ? If i use another solver of openfoam, do i change mesh mode of propeller? 2) How to calculate value of boundary condition of Problem? which is turbulence model i can choose for solver this problem? 3) Do you have tutorials OpenFoam relation simulation flow through propeller? please share me...? Please help me... Thank you very much. Baoaero. 

September 9, 2013, 04:17 

#4 
Senior Member

Hi,
There are two options in OF to solve the problem, one is SRF and another one is MRF. Getting torque and force from MRFSimpleFoam is very simple, just you need to copy and paste the function in your controlDict file. (the function is from the forum only), but I am not sure how to get torque and force from SRF solver, I dont think the function will work with SRF solver. I can help you for MRFSimpleFoam solver, if you like give me your email id, I will send you the tutorial. Regarding the turbulence model, its up to your need. If you are interested to calculate stall, the lowRe model is appropriate, then your Y+ value should be 1, otherwise you can use hiRe model, which the Y+ range should be 30300. Thanks, Sivakumar 

September 9, 2013, 04:40 

#5 
New Member
DANG QUOC BAO
Join Date: Apr 2013
Posts: 12
Rep Power: 5 
Dear Sivakumar
Thank you for your advances. My email; baodangacv@yahoo.com or quocbao@vietnamairport.vn. I will use MRFSimplefoam for simulations propeller. I need calculate force and torque of propeller. How will i refine mesh model of propeller for using solver MRFSimplefoam?. Please help me...Thanks you very much Baoaero. 

September 9, 2013, 21:13 

#6 
New Member
DANG QUOC BAO
Join Date: Apr 2013
Posts: 12
Rep Power: 5 
Dear Sivakumar
I received the file fan tutorial from you. Thank you for your sharing. Can you guide me for generating Mesh model of Propeller when i use MRFSimplefoam. How many calculated domain of Mesh model? Please help me... Thank you very much. Baoaero 

September 10, 2013, 03:33 

#7 
Senior Member

Hi,
Have you gone through the tutorial? I have explained everything in that. The problem is I dont know how you want to model your propeller, in my case I am using 3 volumes. Inlet volume, fan volume , and outlet volume. go through the tutorial once again then you will come to know. Thanks, Sivakumar 

October 1, 2013, 10:44 

#8 
New Member
Join Date: Sep 2013
Posts: 12
Rep Power: 4 
hi, i hope i can use this thread for my question. i want to simulate a kind of propeller, too. i desgined the propeller in solidworks and put it with snappyhexmesh in a mesh created up by blockmesh. the propeller should rotate in still water. so there is no inflow. my question ist, who to set the boundery settings? i user to solve the problem the SRFSimpleFOAM solver. i set the inlet:
Code:
inlet { type SRFVelocity; inletValue uniform (0 0 0); relative yes; value uniform (0 0 0); the shape of the propeller is: Code:
type fixedValue; value uniform (0 0 0); 

October 2, 2013, 02:51 

#9 
New Member
Thomas Reviol
Join Date: Jul 2011
Location: Germany, Kaiserslautern
Posts: 25
Rep Power: 6 
Hi,
"slip" for free surface and "fixedValue" for propeller shape are ok. And I never set an inlet condition, too. Are the boundaries of your fluid domain open for in and outflow? In this case you could use an "inletOutlet" condition. When your fluid domain is a vessel from process industry, you need neither an inlet nor an outlet. In this case all your boundaries are walls. I hope I understood your question correctly and I could help. Regards Thomas 

October 2, 2013, 02:57 

#10 
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Join Date: Sep 2013
Posts: 12
Rep Power: 4 
hi Thomas, thank you for your answer. the bounderies are patches, except the propellerboundery, which is a wall.
what do you mean with "open for in and outlet"? with fluid domain, you mean the initial conditions? the propeller should be in a "open ocean", no borders etc. in german: Hallo Thomas, danke für deine Antwort. Eigentlich hab ich nur patches, außer dem Propeller, welche eine wall ist. Was meinst du mit "open for in and outlet" und "fluid domain"? der propeller soll im offenen wasser sein, also keine grenzen oder hindernisse. 

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