KAPLAN TURBINE

Kaplan turbine is an axial flow, low head, high specific speed, reaction type turbine. There is a similar turbine known as propeller turbine having fixed vane in place of adjustable vane as in Kaplan turbine.

Kaplan turbine has the following components (Figures 9.13 and 9.14):

Figure 9.13 Main Components of Kaplan Turbine

Figure 9.14 Kaplan Turbine

Scroll Casing: Its function is very similar to scroll casing in Francis turbine as explained earlier. It reduces the eddies formation and hence minimizes the eddy loss.

Guide Mechanism: It has similar function as in Francis turbine.

Hub, Vane/Runner: The extended bottom end of shaft is known as hub. On the periphery of hub 3−6 vanes are mounted that are fixed in propeller turbine and adjustable in Kaplan turbine. Propeller turbine is used where head and load are constant, but Kaplan turbine is used where load and head are variable. During operation, vanes are adjusted by servomotor mechanism. Servomotor mechanism consists of a cylinder with a piston working under oil pressure on either side.