1.A jet water issues from a nozzle with a velocity 20 m/s and it impinges normally on a flat plate moving away from it at 10 m/s. The cross-sectional area of the jet is 0.01 m2 and the density of water = 1000kg/m3. The force developed on the plate is
(a) 1000 N
(b) 100 N
(c) 10 N
(d) 2000 N
(1 Mark, 1990)
5. A centrifugal pump running at 500 rpm and at its maximum efficiency is delivering a head of 30m at a flow rate of 60 litres per minute. If the rpm is changed to 1000, then the head H in metres and flow rate Q in litres per minute at maximum efficiency are estimated to be
(a) H = 60, Q = 120
(b) H = 120, Q = 120
(c) H = 60, Q = 480
(d) H = 120, Q = 30
(2 Mark, 2003)
7. At a hydro electric power plant site, available head and flow rate are 24.5 m and 10.1 m3/s respectively. If the turbine to be installed is required to run at 4.0 revolution per second (rps) with an overall efficiency of 90%, the suitable type of turbine for this site is
(2 Mark, 2004)
9. A centrifugal pump is required to pump water to an open water tank situated 4 km away from the location of the pump through a pipe of diameter 0.2 m having Darcy’s friction factor of 0.01. The average speed of water in the pipe is 2 m/s. if it is maintain a constant head of 5 m in the tank, neglecting other minor losses, the absolute discharge pressure at the pump exit is
(a) 0.449 bar
(b) 5.503 bar
(c) 44.911 bar
(d) 55.203 bar
(2 Mark, 2004)
9. In a Pelton wheel, the bucket peripheral speed is 10 m/s, the water jet velocity is 25 m/s and volumetric flow rate of the jet is 0.1 m3/s. If the jet deflection angle is 120° and the flow is ideal, the owe developed is:
(a) 7.5 kW
(b) 15.0 kW
(c) 22.5 kW
(d) 37.5 kW
(1 Mark, 2006)
10. A large hydraulic turbine is to generate 300 kW at 1000 rpm under a head of 40 m. for initial testing, a 1:4 scale model of the turbine operates under a head of 10 m. the power generated by the model (in kW) will be
(2 Mark, 2006)
11. A horizontal shaft centrifugal pump lifts ware at 65°C. The suction nozzle is one meter below pump centerline. The pressure at this point equal 200 kPa gauge and velocity is 3 m/s. Steam tables show saturation pressure at 65°C is 25 kPa, and specific volume of the saturated liquid is 0.001020 m3/ kg. The pump Net Positive suction Head (NPSH) in meters is:
(2 Mark, 2006)
12. A model of a hydraulic turbine is tested at a head of 1/4th of that under which the full scale turbine works. The diameter of the model is half of that of the full scale turbine. If N is the RPM of the full scale turbine, the RPM of the model will be
(2 Mark, 2007)
14. The inlet angle of runner blades of a Francis turbine is 900. The blades are so shaped that the tangential component of velocity at blade outlet is zero. The flow velocity remains constant throughout the blade passage and is equal to half of the blade velocity at runner inlet. The blade efficiency of the runner is
(2 Mark, 2007)
14. Water, having a density of 1000 kg/m3, issues from a nozzle with a velocity of 10 m/s and the jet strikes a bucket mounted on a Pelton wheel. The wheel rotates at 10 rad/s. The mean diameter of the wheel is 1 m. The jet is split into two equal streams by the bucket, such that each stream is deflected by 120°, as shown in the figure. Friction in the bucket may be neglected. Magnitude of the torque exerted by the water on the wheel, per unit mass flow rate of the incoming jet, is
(a) 0 (N.m)/(kg/s)
(b) 1.25 (N.m)/(kg/s)
(2 Mark, 2008)
15. A hydraulic turbine develops 1000kW power for a head of 40m. If the head is reduced to 20m, the power developed (in kW) is
(1 Mark, 2010)
17. The velocity triangles at the inlet and exit of the rotor of a turbo-machine are shown. V denotes the absolute velocity of the fluid, W denotes the relative velocity of the fluid and U denotes the blade velocity. Subscripts 1 and 2 refer to inlet and outlet respectively. If V2 = W1 and V1 = W2, then the degree of reaction is
(1 Mark, 2012)
18. In order to have maximum power from a Pelton turbine, the bucket speed must be
(a) Equal to the jet speed
(b) Equal to half of the jet speed
(c) Equal to twice the jet speed
(d) Independent of the jet speed
(1 Mark, 2013)
19. An ideal water jet with volume flow rate of 0.05 m3/s strikes a flat plate placed normal to its path and exerts a force of 1000 N. Considering the density of water as 1000 kg/m3, the diameter (in mm) of the water jet is ___.
(2 Mark, 2014)
21. At the inlet of an axial impulse turbine rotor, the blade linear speed is 25 m/s, the magnitude of absolute velocity is 100 m/s and the angle between them is 25°. The relative velocity and the axial component of velocity remain the same between the inlet and outlet of the blades. The blade inlet and outlet velocity triangles are shown in the figure. Assuming no losses, the specific work (in J/kg) is ___.
(2 Mark, 2014)
22. Kaplan water turbine is commonly used when the flow through its runner is
(a) Axial and the head available is more than 100 m
(b) Axial and the head available is less than 10 m
(c) Radial and the head available is more than 100 m
(d) Mixed and the head available is about 50 m
(1 Mark, 2014)
23. Which of the following statements are TRUE, when the cavitation parameter σ = 0?
(i) The local pressure is reduced to vapour pressure
(ii) Cavitation starts
(iii) Boiling of liquid starts
(iv) Cavitation stops
(a) (i), (ii) and (iv)
(b) Only (ii) and (iii)
(c) Only (i) and (iii)
(d) (i), (ii) and (iii)
(2 Mark, 2015)
24. Consider two hydraulic turbines having identical specific speed and effective head at the inlet. If the speed ratio (N1/N2) of the two turbines is 2, then the respective power ratio (P1/P2) is ___.
(1 Mark, 2016)
26.The blade and fluid velocities for an axial turbine are as shown in the figure.
The magnitude of absolute velocity at entry is 300 m/s at an angle of 650 to the axial direction, while the magnitude of the absolute velocity at exit is 150 m/s. The exit velocity vector has a component in the downward direction. Given that the axial (horizontal) velocity is the same at entry and exit, the specific work (in kJ/kg) is____.
(1 Mark, 2016)
27. The water jet exiting from a stationary tank through a circular opening of diameter 300 mm impinges on a rigid wall as shown in the figure. Neglect all minor losses and assume the water level in the tank to remain constant. The net horizontal force experienced by the wall is ___ kN. Density of water is 1000 kg/m3. Acceleration due to gravity g = 10 m/s2.
(2 Mark, 2016)
28. Which one of the following statement is true?
(a) Both Pelton and Francis turbines are impulse turbines.
(b) Francis turbine is a reaction turbine but Kaplan turbine is an impulse.turbine.
(c) Francis turbine is an axial – flow reaction turbine.
(d) Kaplan turbine is an axial – flow reaction turbine.
(1 Mark, 2017)
29. A 60 mm diameter water jet strikes a plate containing a hole of 40 mm diameter as shown in the figure. Part of the jet passes through the hole horizontally, and the remaining is deflected vertically. The density of water is 1000 kg/m3. If velocities are as indicated in the figure, the magnitude of horizontal force (in N) required to hold the plate is _____.
(2 Mark, 2017)
30. For a Pelton wheel with a given water jet velocity, the maximum output power from the Pelton wheel is obtained when the ratio of the bucket speed to the water jet speed is ____ (correct to two decimal places).
(1 Mark, 2018)
31. A test is conducted on a one-fifth scale model of a Francis turbine under a head of 2 m and volumetric flow rate of 1 m3/s at 450 rpm. Take the water density and the acceleration due to gravity as 103 kg/m3 and 10 m/s2, respectively. Assume no losses both in model and prototype turbines. The power (in MW) of a full sized turbine while working under a head of 30 m is ___ (correct to two decimal places).
(2 Mark, 2018)
32. As per common design practice, the three types of hydraulic turbines, in descending order of flow rate, are
(a) Kaplan, Francis, Pelton
(b) Pelton, Francis, Kaplan
(c) Francis, Kaplan, Pleton
(d) Pelton, Kaplan, Francis
(1 Mark, 2019)
33. An idealized centrifugal pump (blade outer radius of 50 mm) consumes 2 kW power while running at 3000 rpm. The entry of the liquid into the pump is axial and exit from the pump is radial with respect to impeller. If the losses are neglected, then the mass flow rate of the liquid through the pump is ____ kg/s (round off to two decimal places).
(2 Mark, 2019)