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CFD Tutorial 1 - How to find torque and Power in Fluent
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- เผยแพร่เมื่อ 16 ม.ค. 2018
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How could we define axis of rotation, whether it's positive or negative
Hi, Looking for assistance in a simulation to compare power or torque output of a conventional wind turbine, and a new innovative design. financial compensation will be provided, can you assist? how can we contact you ?
I am trying to plot the moment about the shaft of my reactor vs time. So I created a report definition for the moment and put the axis as 0,0,1 (z axis) and the moment centre as (0,0,0) which is the centre of the bottom of my reactor, and selected the shaft's named selection. But the moment doesn't reach a steady state constant value after sometime (although I plotted turbulent kinetic energy as a function of time, and it reached a steady state value constant value). Can you please tell me how can the moment's value be made to reach a steady-state value?
Hello could you show me the NREL wind turbine cfd profile .?
Hello,
I am working on the vertical axis water turbine project with Ansys Fluent (multiphase flow: VOF method). After the computations, the average Monitors value I got was a negative value. This would suggest a negative torque value which is clearly wrong, I do not know the exact reason for this . I am getting negative moment values when I put moment center as (0 0 0) and moment axis as (0 0 1). but I get the positive moment when I put (0 0 -1) direction.
I would really appreciate any help you can offer.
Thanks
negetive torque means the the turbine is driving instead of being driven. try reducing rotational speed. Might work
What is the difference between 1 and -1 in moment axis
And is this a correct way, I mean that just changing the sign
I can't understand, why you took -1 in rotation axis direction I.e in frame motion. Could you please explain that
It is based on right hand rule. If you wrap your four figures along rotaton of turbine, you will see that your thumb will be poitng in negative direction.
Sir, can coefficient of moment (C.M) value be greater then 1? I am getting more then 1 in some case.I am doing simulation for inline savoinus turbine in transient mode.
Did you find any solution ?
@@iicr7ii582 yes bro. I have changed mesh quality. I took absolute velocity instead of relative velocity. So, now am getting C.M value less than 1.
SIr, confusion regarding the axis of rotation. will it make a difference if you give -ve z axis and +ve z axis direction while calculating torque?
It will only make values -ve or positive. Magnitude will remain same
Hi, Thanks for sharing valuable information. The power calculated in this video is due to fluid, can we include fan weight in shaft power calculation.
you can do it manually as you know the weight of your fan. But it is not done normally.
Hi it was very good explanation and it was helpful.
I am little sceptical, when we theoretically calculate torque we use mass moment of inertia and angular acceleration but here we are just considering the resulted mass momentum, where we never define any mass or moment of inertia.
Can you please advise me or guide me on this, if I am missing out something or if I am thinking it in different way
You are confusing Torque we calculate in mechanics and in Fluid Mechanics.
@@CFD_Mechanic Can you please elaborate what you are trying to say, I didnt understood your comment
The way i see , you are calculating Power = Torque * ω.
Torque of the wall is obtained from CFD simulation and ω might be your input as in rpm or radians
Sir im doing project on vertical wind axis turbine.
how to decide the value of omega?
It should be decided when you were designing it on paper. However you can choose inlet velocity as 5 m/s and choose appropriate TSR (Tip speed ratio = V/wr, where V = incoming velocity which is supposed to be 5 m/sec, r is radius of tip and w is omega in rad/s)
Thank you sir!
Hey friend, I am also currently working on Vertical Axis Turbine can I contact you I need help?
@@CFD_Mechanic But TSR=wr/V , where V=inlet wind velocity, You said opposite right?
@@karannagvekar2929 yes you are correct. Your formula is correct.
What positive mean in torque?
Hi quick question, I understand you calculated the torque on the fan. Was this torque the average torque, max or minimum? Just looking for clarification thanks.
Average torque over whole fan
Sir, besides looking for torque, what else can be found in fluent analysis, for example in blade wind turbines, fan blades, or what model are you analyzing?
it is centrifugal fan
Sir, I am working on vertical axis wind turbine in your case you have already given rpm as input and calculated the power using that rpm but in my case i want to get the rpm of my blade from fluent as i have kept my blade in wind tunnel and flowing a air at constant velocity. Pls help
How did you design a wind turbine? At that point you must have idea about rpm.
@@CFD_Mechanic Sir i have simply made a savonius turbine model on design modeler with aspect ratio 1 (D=500 mm and H=500 mm) and analyzing it . I am getting the torque from ansys but how can i get the rpm. pls sir advice
@@DEEPAKSINGH-sb6jw rpm can be found from analytical calculations
@@CFD_Mechanic Sir it means that we can not get rpm from ansys fluent? Sir analytical calculation means for getting power i have to calculate omega by dividing wind velocity to radius of turbine? sir pls suggest
@@DEEPAKSINGH-sb6jw yes . or use TSR formula or velocity triangle.
why moment center is 1000 mm, when counting torque, why not with 0 0 0 sir?
it can be anywhere on z axis and it will make no difference...
Can you please share the ansys archieve file?..i am a student please help!
It is available in Mastering ANSYS CFD level 2 course on udemy
@@CFD_Mechanic Can you pleas share me the free link..Becaue i have budget issues after lockdown..
Sir i found out the power of a ceiling fan from the way you told. I got 27watt but the power of a ceiling fan is usually upto 70 watt. Can you please explain it?
There can be many reasons of this discrepancy. Your geometric model, your boundary conditions, your rpm, physical models you chose for your case, mesh etc.
@@CFD_Mechanic if want to add some weights in it like of motor etc how to do it on fluent?
Also i need a little help on sloidworks. I want to inc to rake angle of the blades. Can you help with that?
@@ayesha1666 There is no point of adding motors etc in CFD simulation. It wont make any difference.
Check some tutorials on TH-cam on this topic.
Sir, torque which we obtain in that console is which torque?Is it either average torque or torque at particular time step?
it is steady state case. So for transient case you can say it is torque at particular time step.
@@CFD_Mechanic So what value of torque should I use to get Output Power to get Cp?
@@karannagvekar2929 Average value. Make a monitor (both file report and report plot) for torque with every time step. Disregard data for the first time steps when solution is developing. Once solution is periodic in nature, it will show you value of torque varying in cyclic fashion. Like sine wave etc. Now again disregard few cycles of this converged solution and then use data of last five cycles. Import that file into excel and take average of all time steps. Use that torque and multiply with omega (rad/s) and you will get average power.
Then divide this power with theoretical power to get the value of cp at that particular tip speed ratio. But I am wondering why you are running this case as transient????
@@CFD_Mechanic since this turbine makes use of oscillating wave column the condition will vary with time as waves oscillate periodically.Am i correct?
Sir I need help for Savonuis Wind Turbine simulation,How can i contact you?
im not the author oh this video, but you can contact me at jaidi96@gmail.com