Changes in power generation performance of an undershot cross-flow-type hydraulic turbine in an irrigation channel due to snow masses passing through the rotor.

This study is focused on the development of a microhydraulic turbine that can stably and efficiently generate electricity even in channel where snow masses frequently flow down. A hydraulic turbine of an undershot cross-flow type was installed in an irrigation channel, and the change in the turbine performance was measured when spherical snowballs were released one by one from the upstream. The observation of the snowballs passing through the turbine was also conducted. Consequently, the variations in the power generated by the rotor were classified into three modes based on the motion of the snowballs, and could be organized by the ratio of the snowballs' cross-sectional area to the product of the rotor width and blade interval. Furthermore, the emergence of the power output overshoot phenomenon, in which the power output temporarily increases compared to clear water when the rotor restarts after stopping, was identified, and the relationship between the amount of loss when the rotor stops and that of electric energy gained during the overshoot was clarified. Certain guidelines for the installation of the undershot cross-flow type in irrigation channels of snowy regions was successfully obtained.