How can I calculate the power coefficient(cp) and optimal tip speed ratio of micro-generation wind turbine?

Hi all, I am trying to calculate the output power of wind turbine and the power should be zero below cut in and above cut out and equal to rated from rated speed till cut out

my question is what about the part from cut in till rated speed , i used the general equation to calculate it which is

p=0.5*swept area* air density*capacity factor *v3

the problem is some values above rated power is there any thing wrong i need help

vertical axis wind turbine is rotating with a known RPM. Practically, how to measure the torque by utilizing the rotating shaft attached to the turbine?

I have a question on Cp in the wind turbine. I have calculated the moment in the z-axis as my rotor also rotors along the z-axis. I got the moment values from my simulation. I applied the procedure which ansys recommended formula (P= torque x rotational velocity) for extracting power from the turbine. I got huge discrepancies between actual and theoretical. After calculating power, I have calculated Cp it comes around 0.8 to 1, but the Betz limit is 0.59. plz help me to calculate the Cp.

Conditions :

Turbine Aera =17.5 m2

R=3.5m

V=3

omega=2.14 rad/s

TSR=2

Fluid water (990 is the density)

 

Hi, I would like to calculate the rotational speed of a wind turbine with a power of 20 kw and average wind speed of 9 m / s.

I want to know if there is a formula or a specified range.

For low and medium wind turbine the optimum value of pitch angle is zero. So when we do dP/dw =0, we will get the optimum value of Cp and lambda. To do the same we will get dP/dw proportional to dCp/dw. But Cp is function (lambda, beta=0) and from the article i found that dCp/dw = (dCp/dlambdai)(dlambdai/dw). However lambdai is the variable it is the function of lambda and beta . For low and medium wind turbine lambdai=(1/lambda)-0.035.

So instead of dCp/dw = (dCp/dlambda)(dlambda/dw) how can we do dCp/dw = (dCp/dlambdai)(dlambdai/dw). Please clarify anybody regarding the same.

With Thanks and Regards

Rajin M Linus

Hello everyone!

I'm doing a simulation in fluent and at some point, usually after the first 15 steps, the error appears:

Divergence detected in AMG solver: temperature

Divergence detected in AMG solver: temperature

Error at host: floating point exception

Error at Node 0: floating point exception

Error at Node 1: floating point exception

===============Message from the Cortex Process================================

Compute processes interrupted. Processing can be resumed.

==============================================================================

Error: floating point exception

Error Object: #f

I'm compiling a UDF file, Time transient, convergence criterion relative, number of time steps 1000, able Specified Operating Density like zero kg/m^3. The mesh is refined in the best possible way.

What is the reason behind it?

Best regards.

As I start the simulation of bubble column (air-water system), just after 15 iterations, it displays "floating point exception" and shows "divergence detected in AMG solver". What is the reason behind it?

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. 

C_p = C_t* 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 

Hi, I am simulating a horizontal axis wind turbine using Ansys Fluent. I want to validate the model by calculating the turbine power at different wind speed. Using Fluent, I calculate the torque and moment coefficient. But I don't know which equation must I use to calculate the power. Could you tell me which of these equation is the correct one

1- Power=Torque*angular velocity;

2- Power=Torque*angular velocity*Betz limit;

3- Power=Torque*angular velocity*Cp(=Ct*TSR);

4- Power=Cp*wind power;

5- Power=Cp*wind power* Betz limit ?

Thank you.