Experimental Analysis of Effect of Canal Geometry and Water Levels on Rotary Hydrostatic Pressure Machine

A rotary hydrostatic pressure machine (RHPM) is a hydropower converter for very low head applications (less than 2.5 m). An RHPM can be installed in straight canals, because its wheel can generate a hydraulic head, as a result of the created dam effect. Some new experimental results on an RHPM are presented in this paper. Because of the asymmetric shape of the wheel, the effects of the canal width and the lateral position of the wheel inside the canal have been studied. The water entrance process has been found to be very sensitive to the presence of the canal walls: the results pertaining to the side of the wheel where the blades touch the water first show that the minimum distance between the canal wall and the side of the wheel should be 0.3 times the width of the wheel in order to maintain an optimal wheel performance. Upstream and downstream water level variations have also been studied. Higher upstream water levels than the water levels adopted in previous studies (coincident with the upper edge of the hub) can lead to benefits. The results shown in this manuscript may be useful for practical applications in order to understand the optimal position of an RHPM inside a canal, the minimum canal width and the optimal water levels.