Wind Turbine © D Hoult 2010
Consider a cylinder of air moving towards the turbine
Consider a cylinder of air moving towards the turbine
Consider a cylinder of air moving towards the turbine
Consider a cylinder of air moving towards the turbine If all the air in a cylinder of length L interacts with the turbine in time t, then the speed of the air is u =
Consider a cylinder of air moving towards the turbine If all the air in a cylinder of length L interacts with the turbine in time t, then the speed of the air is u = L/t
K. E. possessed by this air is
K. E. possessed by this air is ½ m u2
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is r V
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is r V =
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is r V = r A L
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is r V = r A L Therefore the power (theoretically) available from this cylinder of air is given by
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is r V = r A L Therefore the power (theoretically) available from this cylinder of air is given by ½ r A L u2 = t
K. E. possessed by this air is ½ m u2 mass of air in the cylinder is r V = r A L Therefore the power (theoretically) available from this cylinder of air is given by ½ r A L u2 = ½ r A u3 t
If the average speed of the air in the cylinder after it has interacted with the turbine is v then the efficiency of the turbine is given by
If the average speed of the air in the cylinder after it has interacted with the turbine is v then the efficiency of the turbine is given by power in air before – power in air after power in air before
If the average speed of the air in the cylinder after it has interacted with the turbine is v then the efficiency of the turbine is given by ½ r A u3 - ½ r A v3 ½ r A u3
If the average speed of the air in the cylinder after it has interacted with the turbine is v then the efficiency of the turbine is given by u3 – v3 u3