The development of the rotary hydraulic pressure machine

There currently exists a demand for economical hydro-electric machinery that operates at low heads and moderate flows; sites where the drop from a higher water level to a lower one is quite small, in the order of 1-3m, with flows between 5m3/s and 15m3/s. The economics which determine a machine’s viability are a function of its size and complexity, its efficiency characteristics and its power output. The author believes that the most promising route lies with the Rotary Hydraulic Pressure Machine (RHPM), a concept developed from the Staudruckmaschine (SDM) by Brinnich (2001). This paper analyses the SDM in detail using scale model tests. These tests found that the SDM had many deficiencies resulting in unnecessarily low efficiencies and flow capacity, which is the volume of water which the wheel can process per second per metre width. The scale tests also aided the development of a new detailed theory of operation for wheels operated by hydraulic pressure. Significant modifications are then proposed for the SDM to address its deficiencies. These revise its channel design, blade shape, and support structure. The result is effectively a new machine, the RHPM, which is expected to have a 20% higher efficiency, greater flow capacity and smoother operation than the SDM. The RHPM can be built at any site; however it is especially suitable for incorporation into existing weir structures with minimal modifications being required to the weir structure itself. Furthermore, the RHPM is unlike most conventional rotodynamic machines as it is symmetrical and therefore fully reversible. This property means it also has potential application in tidal flow environments