For high water heads and low discharge, Pelton Wheel is considered as the most popular impulse turbine which is used successfully all over the world. Still many scientist and engineering professionals are busy in developing improved types of impulse turbine. Some of them got success in developing new one but these improved turbines are not having practical importance due to many reasons. Yet from education point of view, here I am going to share some knowledge on different types of turbines.
01) Girard Turbine
In a Girard Turbine, the direction of flow of water is parallel to the axis of wheel. The guide vanes allow the water to impact through two diametrically opposite quadrants. To generate large power under low water head, Girard Turbine is used. In case of low heads, the turbine wheel is kept horizontal and for larger heads, the wheel is kept vertical.
02) Turgo Turbine
In this turbine also, the flow of water is kept parallel to the axis of the wheel as of Girard Turbine and used one or two nozzles as like Pelton Wheel. In Turgo turbine, the jet of water strikes buckets at one end and leaves at the other end while in pelton wheel it strikes at centre of bucket. The flow of water is regulated by spear. For the same jet diameter and discharge, the diameter of Turgo turbine is much less than that of Pelton Wheel but its peripheral speed is higher than that of Pelton Wheel.
03) Banki Turbine
In a Banki Turbine, the jet of water after striking the buckets is made to pass through the runner which gives some impulse to the runner. It is considered that the velocity of water is utilized twice to improve the efficiency of turbine. In actual practice, the theory of using twice the velocity didn’t get success. Though engineers failed to succeed in banki turbine, this theory is successfully utilized in steam turbines.
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