AXIAL FLOW TURBINES 1
Similar in many aspects to the Kaplan turbine, the Axial Flow turbine is however extremely versatile and adaptable to a wider range of operating and installation conditions.
As with the Kaplan turbines, the Newmills Hydro Axial Flow turbines have a high specific speed, which means that direct coupling to the generator is possible at higher heads and lower flows.
However with lower heads and high flow site conditions, a speed increasing facility is required on most applications.
As such, a gearbox would be recommended for turbines whose output exceeds 75kW but, below this, a belt drive is acceptable.
The Axial Flow turbine runner comprises a cast hub on which blades are mounted. The hub is normally cast in S.G. Iron with highly stressed hubs cast in Steel.
The blades are normally cast in Aluminium Bronze or Stainless Steel depending on the operating conditions and quality of the water passing through the turbine.
Again, the runner blade operating mechanism is located within the hub whereby angular movement of the blades occurs via a mechanical linkage system, operated by a push rod through the centre of the main turbine shaft, which is operated by an hydraulic actuator.