Net Power Generated by Flettner Rotor for Different Values of Wind Speed and Ship Speed

摘要

In global scenario, shipping and inland water transport became a very popular and necessary mode of goods transport, as it covers approximately 90% of the tonnage of all traded goods. That contributes approximately 2.8% to 3% of annual global greenhouse gas emissions, especially CO_2. The marine transportation is expected to increase further more as energy demand is expected to grow by 25% from 2014 to 2040. Environmental concerns for the reduction of CO_2 emission compel the shipping industry to reduce fossil fuel consumptions by increasing efficiency in shipping transportation and by adopting renewable energy sources for shipping. Wind energy for ship transportation is abundant and its potential is also high on seas. Wing sails, Airborne wind turbines, Wind kites, Flettner rotors, etc. are different techniques to harness wind energy for shipping. Flettner Rotor technique is one which provide thrust force for propelling the ship. In this paper, a cylindrical Flettner rotor (without endplates) of 12.5 m height and 2.1 m diameter is used for the theoretical analysis to estimate net power generation by Flettner rotor using the values of lift coefficient of C_L = 12.5 and drag coefficient of C_D = 0.2. Calculations have been made for ship speeds of 15 knots and 20 knots and wind speed variation from 5 m/s to 20 m/s at all true wind angles. Net power output obtained is maximum at true wind angles of 100 degree and 260 degree. At ship speed of 15 knots, the maximum values of net power obtained is 42.2 kW, 124 kW, 239.9 kW and 386.7 kW at wind speeds of 5 m/s, 10 m/s, 15 m/s, 20 m/s respectively. Whereas, at ship speed of 20 knots maximum values of net power is 68.2 kW, 189.5 kW, 358.8 kW and 575.2 kW at wind speeds of 5 m/s, 10 m/s, 15 m/s, 20 m/s respectively. Calculations have also been made for net power generation from Flettner rotor for various values of coefficient of rotation.