An experimental investigation into the effect of rotor blade sweep on the performance of the variable-pitch Wells turbine

Abstract

The paper describes an experimental investigation into the effect of rotor blade sweep on the performance of the variable-pitch Wells turbine. The blades tested included two sets of eight symmetrical constant chord NACA 0015 blades (one set had 30° backward sweep, while the other was unswept), two rotor solidities and blade pitch angles of 0° and 20°. The aim of the present experiments was to investigate and compare the aerodynamic performance of the backward swept and unswept blades for different rotor solidities and pitch angles. The measurements covered flowrate, pressure drop, torque and rotor speed. Traversing work with the aid of a directional total static pressure probe yielded more detailed information on the performance of each set of rotor blades. Experimental results have shown that the swept back design of the blades produces a positive value of efficiency and torque over a much wider operating range than the standard unswept NACA 0015 blades, but at the expense of peak efficiency.