I am trying to simulate Savonius hydrokinetic turbine through CFD. Problem I am facing is that value of Cp or Ct is always increasing with respect to TSR and not decreasing at any point in whole range of TSR used (0.3-1.2).For calculation of Cp, I am using following formula.
Cp = Ct* TSR
For unsteady simulation Time step size according to angular velocity of turbine were set for 360 step for a complete revolution of turbine.
Simulation were carried out for 3 revolution and Cm- history were stored for each time step. Last 360 time step were used to calculate average Cm (coefficient of moment).
and I used this avg . Cm as Ct (torque coefficient) and calculated Cp. But Value I found for whole range is always increasing.
Also tried Steady simulation and calculated direct torque from Fluent, same problem was found.
I am stuck in this problem since last 3 month. Pls Suggest me where I am making mistake
Sir, i hav gone through this file. But unfortunately, this is not helping me.
If you are comfortable with CFD fluent.then plz help me sir, i'll send u my files
Dear Anuj,
I think both of these CFD studies (undergraduate theses) may be very helpful to you:
"Computational Fluid Dynamics study of a vertical axis tidal turbine using a Fluid Structure Interaction approach"
available in: http://hdl.handle.net/2099.1/24449
"Computational Fluid Dynamics study of 2D vertical axis turbines for application to wind and tidal energy production"
available in: http://hdl.handle.net/2099.1/24458
Sincerely,
Jose
https://upcommons.upc.edu/handle/2099.1/24449
https://upcommons.upc.edu/handle/2099.1/24458
Hope your problem have already been solved. Still, my experience suggests that you perform steady state CFD simulation first. Try to understand the flow physics. Validate your simulation with test or reference publications. Then proceed for transient.
Suggestion is following:
There is strong relation between courant number, mesh criteria that you select and the time step of transient simulation. If you can thoroughly understand this conceptual relation, definitely simulation will converge as well as results will be realistic.
hello, i have a somehow similar problem. I am simulating a savonius hydrokinetic turbine in a open channel flow using Ansys fluent. my simulation is two phase but the turbine is submerged completely. The problem is that the average torque value i get from simulation is very higher than experimental results. when i simulate the turbine for 2 or 3 revolutions..as the time steps go up the torque average value become higher
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