Tests were carried out to determine the effect
on turbine efficiency of variations in speed ratio and jet misalignment on two Turgo turbines. The results
were compared to similar tests in the same fixture on a Pelton turbine. Under the best conditions, the
Turgo turbine efficiency was observed to be over 80% at a speed ratio of approximately 0.46, which is
quite good for pico-hydro-scale turbines. Peak efficiencies for both the Pelton and the Turgo turbines
occurred at lower than theoretical ideal speed ratios based on a momentum balance; the reduction in
speed ratio at which peak efficiency occurs is likely caused by inefficiencies in the turbine. Tests of jet
misalignment showed that moving the jet to the inside or outside edge of the turbine blades caused
a drop in Turgo efficiency of 10e20% and reduced the optimal speed ratio by 0.03 (6.5%). Radial
misalignment had a significant adverse impact on both Turgo and Pelton turbines, however, angular
misalignment of the jet is more of a concern for the Turgo turbine. The results stress the importance of
proper system design and installation, and increase the knowledge base regarding Turgo turbine
performance that can lead to better practical implementation in pico-hydro systems.