Effect of Inlet Nozzle Shape on Performance of Darrieus-Type Hydro-Turbine Operated in Small Open Water Channel

A Darrieus-type hydro-turbine has been developed for the utilization of extra low head hydraulic energy. In the case of a ducted Darrieus-type hydro-turbine which consists of an intake, a runner, a casing and a draft tube, it has been found that the Darrieus runner with the narrow intake can generate larger torque without deterioration of efficiency than that with the parallel intake with the constant width. In this paper, the effect of the shape of the inlet nozzle on the performance of the Darrieus-type hydro-turbine operated in open channel flow is investigated both experimentally and numerically. Tested nozzles are two types of two-dimensional symmetric inlet nozzle, Half Diameter curved nozzle (HD nozzle) and Straight Line nozzle (SL nozzle). As a result, the Darrieus hydroturbine with SL nozzle generates larger power and yields higher efficiency than that with HD nozzle. In addition, the effects of nozzle converging angle and outlet width of SL nozzle on the turbine performance are investigated. As a result, it is found that the Darrieus hydroturbine with SL nozzle having large converging angle generates larger power with higher efficiency than that with the nozzle having small converging angle. And then, it is found that the generated power increases when SL nozzle with large outlet width is installed.