EXPERIMENTAL INVESTIVATION ON THE RELATIVE EFFECTS OF GUIDE BLADES AND A SECOND REST POINT ON THE MAIN SHAFT ON CHARACTERISTICS OF MODIFIED AGNEW MICROHYDRO

Agnew turbine is an axial flow micro hydro turbine, which was originally designed and manufactured in Scotland by an ex-lecturer of the University of Glasgow, to operate without guide blades. Later due to a joint research program between the Iranian Research Organization for Science and Technology (IROST) and the University of Glasgow it was developed to operate under low head and limited flow potentials in rural areas of Iran. Therefore a (2:1) model of this turbine was manufactured and tested at IROST. Later, improvements were made to this turbine by installation of guide blades using their support as a second rest point for the main shaft of the turbine which originally worked as a cantilever. Although the improvements had great impacts on the characteristics of the turbine yet, changing angle of attack of the guide blades showed little effects on turbine s efficiency. Therefore it was decided to remove the guide blades, leaving the second rest point intact. The turbine was then tested under various conditions to find the effects of elimination of the guide blades on the efficiency of the turbine. Test results presented here shows that, removal of the guide blades do not have significant impact on the actual performance of the turbine, indicating that the second rest point plays relatively greater role as far as the improvement in characteristics of the Agnew turbine is concerned. Hence, the elimination of the guide blades would result in a new simpler design for the modified Agnew turbine with no adverse effects on the turbine characteristics. This in turn leads to simplified manufacturing process and also in reduction of overall manufacturing costs of the modified Agnew turbine.

Keywords:

Agnew Turbine , Guide Blade , Hydro Turbine , Performance , characteristics