I'm currently working on a VAWT simulation using FLUENT and i intend to come out with the power curve of my turbine. However, the torque values keep increasing with the RPM which is not quite true. Anybody had similar problem could advice for possible solution..Thanks in advance
Dear Didane,
Please recheck your proposed boundary conditions.
Regards
Dear Djamal,
According to Newton's second law, the summation of torque=Moment of inertia * Angular Speed (RPM). As the moment of inertia is constant, the torque is proportional to the angular speed. Therefore, If the the RPM increases, the torque increases.
Regards,
Mahmoud
Dear Mahmoud Heshmat, i agree with u. However, every rotating device such as wind turbine has a maximum rotating torque, which means that after reaching that limit it won't generate any useful torque even though the rotational speed is being increased. and thereafter, the torque will start to decrease. The problem with my simulation is, it did not decrease even when it suppose to, because using the experimental and theoretical approach it has decreased.
Thank u all for your kind answers.
Dear Djamal,
The turbine starts rotating and rotation speed increases as long as the aerodynamic torque on the rotor is higher than the total resistance including all negative sources of torque on the system due to rotor inertia, engagement of generator and any measurement system. Once the summation of aerodynamic torque and the resistive ones turn into zero in each revolution, the average aerodynamic torque and RPM will no longer change and the turbine operation will come into a balance.
Hope this can help
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