In order to improve the performance of a Wells turbine, effects of the gap between rotor and guide vane and solidity of the guide vane have been investigated by model testing. The results have been compared with those of the case without guide vane. It is found that the overall characteristics of the turbine are considerably improved by the guide vanes. A suitable choice of design parameters such as the gap and the solidity of the guide vane has been suggested.
Several of the wave energy devices currently studied in the United Kingdom, Japan, Portugal, India and other countries make use of the principle of oscillating water-air column for converting wave energy to low pressure pneumatic energy which in turn can be converted into mechanical energy by a Wells turbine. This turbine rotates in a single direction in an oscillating airflow and therefore does not require a system of non-return valves. There are several reports which describe the performance of the Walls turbine and factors which influence the performance (Inoue et al., 1986; Kaneko et al., 1986; Setoguchi et al., 1986; Raghunathan et al., 1987, 1994). According to these results, the turbine efficiency is lower in comparison with the usual turbines. In this case, the guide vanes before and after rotor may be one of the most effective equipment to improve the turbine performance. The performances of the Wells turbine with guide vanes were studied theoretically (Sturge, 1977; Cato et al., 1990) and experimentally (Inoue et al., 1985; Arakawa et al., 1987) under steady operating conditions so far. But there are many unknown aspects about the favorable configurations of model vanes. In this paper, in order to clarify the performance of the Wells turbine with guide vanes, the effects of the gap between rotor and guide vane and solidity of the guide vane have been investigated by model testing.
