TY JOUR TI ANALYSIS OF AERODYNAMIC PARAMETERS AND ENERGY EFFICIENCY OF VERTICAL AXIS WIND TURBINES KW vertical axis wind turbines KW Darrieus rotor KW Savonius rotor KW combined wind turbines KW energy efficiency JO Vestnik of Astrakhan State Technical University AU Ilyin, R.. AU Shishkin, N.. PY 2018 IS 2018 PB Astrakhan State Technical University