In the case of Francis turbine velocity ratio is defined as

In the case of Francis turbine, velocity ratio is defined as V_3/squareroot 2 H where H is the available head and V_3 is the absolute velocity at the draft tube inlet velocity of/low in the turbine mean absolute velocity at the guide vane inlet velocity at the rotor inlet flow Consider the following statements: A reverse jet protects Pelton turbine from over speeding Runner blades of Francis turbine are adjustable Draft tube is used invariably in all reaction turbine installations Surge shafts is a protective device on penstock Of these statements 1 and 2 are correct 2 and 3 are correct 3 and 4 are correct 1 and 4 are correct Cavitation damage in the turbine runner occurs near the inlet on the concave side of the blades outlet on the concave side of the blades outlet on the convex side of the blades inlet on the convex side of the blades In hydraulic power-generalion systems, surge tanks are provided to prevent immediate damage to draft lube turbine tail race penstocks A centrifugal pump delivers water at the rate of SO litres/s against a total head of 40 metres. Then the power required to drive the pump is 2 kW 15.2 kW 19.6kW 25.8 kW Consider the following characteristics: The fluid enters the pump axially and is discharged radially Maximum efficiency may be of the order of 90% Development of a low head A limited suction capacity Which of the above characteristics are possessed by axial flow pumps? 1 and 2 2 and 3 2 and 4 3 and 4

Solution

11. (d) V3 is the flow velocity at blade inlet

12 (c) 3. Draft tube is used invariably in all reaction turbine installations

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4. Surge shafts is a protective device on penstock

13.  (b) outlet on the concave side of the blades

14. (d) penstocks

15. (c) 19.6 kW Power = pQgH = 1000 * (50 * 10 ^-5 ) * (9.81) * 40 = 19.62 kW

16. (b) 2. Maximum efficiency may be of the order of 90%

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3. Development of a low head