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MCQOPTIONS
This section includes 238 Mcqs, each offering curated multiple-choice questions to sharpen your Fluid Mechanics knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Match List-I with List-II and choose the correct option.List – I List – IIA) Pelton turbine 1. Low head, high dischargeB) Francis turbine 2. Medium head, medium discharge C) Kaplan turbine 3. High head, low discharge 4. Medium discharge, low head |
| A. | A – 3, B – 2, C – 1 |
| B. | A – 2, B – 1, C – 3 |
| C. | A – 3, B – 1, C – 2 |
| D. | A – 2, B – 3, C – 1 |
| Answer» B. A – 2, B – 1, C – 3 | |
| 52. |
Hydraulic efficiency of Francis turbine is |
| A. | Directly proportional to velocity of whirl at inlet and inversely proportional to net head on turbine |
| B. | Directly proportional to velocity of whirl at inlet and net head on turbine |
| C. | Inversely proportional to velocity of whirl at inlet and net bead on turbine |
| D. | Inversely proportional to velocity of whirl at inlet and directly proportional to net head on turbine |
| Answer» B. Directly proportional to velocity of whirl at inlet and net head on turbine | |
| 53. |
A 15 cm centrifugal pump delivers 6 lps at a head of 26 m running at a speed of 1350 rpm. A similarly designed pump of 20 cm size runs at the same speed. What are the most likely nearest magnitudes of discharge and delivery head provided by the latter pump? |
| A. | 11 lps and 46 m |
| B. | 14 lps and 52 m |
| C. | 11 lps and 52 m |
| D. | 14 lps and 46 m |
| Answer» E. | |
| 54. |
In the velocity diagram shown below, u = blade velocity, C = absolute fluid velocity and w = relative velocity of fluid and the subscripts 1 and 2 refer to inlet and outlet. This diagram is for |
| A. | an impulse turbine |
| B. | a reaction turbine |
| C. | a centrifugal compressor |
| D. | an axial flow compressor |
| Answer» B. a reaction turbine | |
| 55. |
A graph between the pressure head in the cylinder and the distance travelled by the piston from the inner dead centre for one complete revolution of crank is known as |
| A. | Slip diagram |
| B. | Crank diagram |
| C. | Polar diagram |
| D. | Indicator diagram |
| Answer» E. | |
| 56. |
Power consumption of centrifugal fans varies with speed (N) and diameter (D) as |
| A. | N3D4 |
| B. | N5D3 |
| C. | N2D5 |
| D. | N3D5 |
| Answer» E. | |
| 57. |
A Pelton wheel turbine operates under a head of 125 m at a speed of 2000 rpm. To operate very close to the maximum efficiency, the mean diameter of the Pelton wheel is nearly |
| A. | 24 cm |
| B. | 48 cm |
| C. | 12.5 cm |
| D. | 36 cm |
| Answer» B. 48 cm | |
| 58. |
It is known that 'H' is the head of water under which the turbine is working. The power developed by a turbine is ________. |
| A. | Directly proportional to H1/2 |
| B. | Inversely proportional to H1/2 |
| C. | Directly proportional to H3/2 |
| D. | Inversely proportional to H3/2 |
| Answer» D. Inversely proportional to H3/2 | |
| 59. |
A centrifugal pump has its impeller of 50 cm diameter at inlet, and it rotates at 1200 rpm. The tangential velocity of the impeller at the inlet is |
| A. | 16π m / s |
| B. | 10π m / s |
| C. | 12π m / s |
| D. | 100π m / s |
| Answer» C. 12π m / s | |
| 60. |
Extracts from the head-discharge characteristics of two centrifugal pumps are tabulated with respective subscripts 1 and 2; monometric head hm is given in meters; and discharge Q is given in lps:Q1214161820Hm50.252.851.350.030.0Hm242.438.835.732.025.0 The pumps are connected in series against a static head of 80 m; the estimate of the total of head losses is \(\frac{{{Q^2}}}{{120}}\)m What is the delivered discharge? |
| A. | 15.80 lps |
| B. | 16.35 kps |
| C. | 17.35 lps |
| D. | 17.75 lps |
| Answer» E. | |
| 61. |
In a centrifugal pump casing, the flow of water leaving the impeller is |
| A. | Radial |
| B. | Centrifugal |
| C. | Rectilinear |
| D. | Free Vortex |
| Answer» E. | |
| 62. |
A pump running at 1000 rpm consumes 1 kW and generates head of 10 m of water. When it is operated at 2000 rpm, its power consumption and head generated would be |
| A. | 4 kW, 50 m of water |
| B. | 6 kW, 20 m of water |
| C. | 3 kW, 30 m of water |
| D. | 8 kW, 40 m of water |
| Answer» E. | |
| 63. |
In a single-acting reciprocating pump, the acceleration head at the beginning of the suction stroke is 3.5 m. If the pump is 1.5 m below the water level in the supply reservoir, the pressure head at the cylinder at that instant, considering the atmospheric pressure as 10.0 m is |
| A. | 2 m (abs) |
| B. | 4 m (abs) |
| C. | 8 m (abs) |
| D. | 16 m (abs) |
| Answer» D. 16 m (abs) | |
| 64. |
A jet of water issued from a nozzle with a velocity 20 m/s on 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 = 1000 kg/m3. The force developed on the plate is |
| A. | 1000 N |
| B. | 100 N |
| C. | 10 N |
| D. | 2000 N |
| Answer» B. 100 N | |
| 65. |
In Kaplan turbine runner, the number of blades is generally of the order _____. |
| A. | 2 – 4 |
| B. | 4 – 8 |
| C. | 8 – 16 |
| D. | 16 – 24 |
| Answer» C. 8 – 16 | |
| 66. |
A 20 cm centrifugal pump runs at 1400 rpm delivering 0.09m3/sec against a head of 45 m with an efficiency of 87%. What is its non-dimensional specific speed using rps as the relevant data component? |
| A. | 0.482 |
| B. | 0.474 |
| C. | 0.466 |
| D. | 0.458 |
| Answer» E. | |
| 67. |
High head hydro-power plant uses |
| A. | Kaplan turbine |
| B. | Francis turbine |
| C. | Pelton turbine |
| D. | The type of turbine used does not depend on head of hydro-power plant |
| Answer» D. The type of turbine used does not depend on head of hydro-power plant | |
| 68. |
A Francis turbine is an- |
| A. | Inward flow reaction turbine |
| B. | Inward flow impulse turbine |
| C. | Outward flow reaction turbine |
| D. | Outward flow impulse turbine |
| Answer» B. Inward flow impulse turbine | |
| 69. |
A Pelton wheel is having a mean bucket diameter of 4 m and is running at 1500 r.p.m. The discharge through nozzle is 0.2 m3/s and net head on the Pelton wheel is 500 m. Determine the power available at the nozzle: |
| A. | 1051 kW |
| B. | 981 kW |
| C. | 551 kW |
| D. | 850 kW |
| Answer» C. 551 kW | |
| 70. |
In a centrifugal pump, the liquid enters the pump from _____. |
| A. | The top |
| B. | The bottom |
| C. | The centre |
| D. | From sides |
| Answer» D. From sides | |
| 71. |
Guide angle as per the aero foil theory of Kaplan turbine blade design is defined as the angle between |
| A. | lift and resultant force |
| B. | drag and resultant force |
| C. | lift and tangential force |
| D. | lift and drag |
| Answer» B. drag and resultant force | |
| 72. |
A hydraulic turbine develops 1000 kW power for a head of 40 m. If the head is reduced to 20 m, the power developed (in kW) is |
| A. | 177 |
| B. | 354 |
| C. | 500 |
| D. | 707 |
| Answer» C. 500 | |
| 73. |
A Kaplan turbine is a/an ______ turbine. |
| A. | Axial flow |
| B. | Mixed flow |
| C. | Radial flow |
| D. | Tangential flow |
| Answer» B. Mixed flow | |
| 74. |
Cavitation in turbines affects turbines in the following ways except |
| A. | Irregular collapse of vapour cavities |
| B. | Vibration of turbine parts |
| C. | loss of turbine material |
| D. | reduction in efficiency of turbine |
| E. | excessive heating of water |
| Answer» F. | |
| 75. |
Consider the following energies with a Pelton turbine:I. Mechanical energyII. Kinetic energyIII. Potential energyThe correct sequence of energy conversion from the entry of the fluid is |
| A. | I, II, III |
| B. | II, III, I |
| C. | III, II, I |
| D. | I, III, II |
| Answer» D. I, III, II | |
| 76. |
A two-dimensional water jet strikes a fixed two-dimensional plate at 30° to the normal to the plate. This causes the jet to split into two streams in which the ratio of larger discharge to smaller discharge is |
| A. | 14 |
| B. | 3 |
| C. | 2 |
| D. | 1 |
| Answer» C. 2 | |
| 77. |
Power in kW required to drive Centrifugal pump with discharge of Q m3/sec, Head in H mtr, specific weight of fluid as ω N/m3 and overall efficiency of pump as η shall be |
| A. | \(\frac{ωH}{Qη}\) |
| B. | \(\frac{ωQH}{η}\) |
| C. | \(\frac{ωQ}{Hη}\) |
| D. | \(\frac{ωQη}{H}\) |
| Answer» C. \(\frac{ωQ}{Hη}\) | |
| 78. |
In an impulse turbine, if the angle of the blade tip at the outlet is 60°, the maximum hydraulic efficiency of the impulse turbine is |
| A. | 80% |
| B. | 75% |
| C. | 90% |
| D. | 60% |
| Answer» C. 90% | |
| 79. |
A Pelton wheel develops 1750 kW under a head of 100 m while running at 200 rpm and discharging 2500 litres of water per sec. The unit power of the wheel will be |
| A. | 3.75 kW |
| B. | 0.75 kW |
| C. | 1.75 kW |
| D. | 0.25 kW |
| Answer» D. 0.25 kW | |
| 80. |
High specific speed of turbine implies that it is _____. |
| A. | Propeller turbine |
| B. | Francis turbine |
| C. | Impulse turbine |
| D. | Francis turbine or impulse turbine |
| Answer» B. Francis turbine | |
| 81. |
If V = absolute velocity of the water jet, u = absolute bucket speed, then the theoretical condition for maximum hydraulic efficiency of a Pelton wheel is obtained at: |
| A. | V = 3u |
| B. | u = 0.5V |
| C. | u = V |
| D. | u = 2V |
| Answer» C. u = V | |
| 82. |
If D is the diameter of impeller at inlet, w is the width of impeller at inlet and vf is the velocity of flow at inlet, then discharge through a centrifugal pump is equal to |
| A. | πDVf |
| B. | DVfw |
| C. | πDVfw |
| D. | πDw |
| Answer» D. πDw | |
| 83. |
Air vessel is used in a reciprocating pump to obtain |
| A. | Reduction of suction head |
| B. | Rise in delivery head |
| C. | Continuous supply of water at uniform rate |
| D. | Increase in supply of water |
| Answer» D. Increase in supply of water | |
| 84. |
A water jet 0.0015 m2 in area issues from a nozzle with 15 m/s velocity. It is made to imping perpendicular on to a plate that moves away from the jet with a velocity of 5 m/s. The force on the plate due to this impact is |
| A. | 150 N |
| B. | 1470 N |
| C. | 340 N |
| D. | 900 N |
| Answer» B. 1470 N | |
| 85. |
A fast centrifugal pump impeller will have |
| A. | forward facing blades |
| B. | radial blades |
| C. | backward-facing blades |
| D. | propeller-type blades |
| Answer» D. propeller-type blades | |
| 86. |
In Kaplan Turbine, the flow velocity: |
| A. | directly proportional to the radius |
| B. | maximum at midpoint of the radius |
| C. | inversely proportional to the radius |
| D. | is constant along the radius |
| Answer» E. | |
| 87. |
If the turbine has kinetic energy and pressure energy of water at its inlet, then such turbine is known as |
| A. | Impulse turbine |
| B. | Reaction turbine |
| C. | Pelton wheel turbine |
| D. | low head turbine |
| Answer» C. Pelton wheel turbine | |
| 88. |
Compared to a cylindrical draft tube, a tapered draft tube |
| A. | Prevents hammer blow and surges |
| B. | Responds better to load fluctuations |
| C. | Converts more of kinetic head into pressure head |
| D. | Prevents cavitation even under reduced discharges |
| Answer» D. Prevents cavitation even under reduced discharges | |
| 89. |
At constant discharge, to increase the head, hydraulic pumps are: ____. |
| A. | Connected in series |
| B. | Connected in parallel |
| C. | Connected in series or parallel |
| D. | Not connected |
| Answer» B. Connected in parallel | |
| 90. |
Lawn sprinkler can be best explained by which of the following equation of property? |
| A. | Energy equation |
| B. | Continuity equation |
| C. | Moment of momentum principle |
| D. | Impulse-momentum principle |
| Answer» D. Impulse-momentum principle | |
| 91. |
A turbine is called as a ‘Reaction Turbine’ if at the inlet of turbine the water possesses: |
| A. | Kinetic energy |
| B. | Pressure energy |
| C. | Kinetic energy and Pressure energy |
| D. | Kinetic energy and Potential energy |
| Answer» D. Kinetic energy and Potential energy | |
| 92. |
A Francis turbine running at 200 rpm develops a power of 5000 kW under a head of 25 m. The power output under a head of 100 m will be |
| A. | 20,000 kW |
| B. | 30,000 kW |
| C. | 40,000 kW |
| D. | 50,000 kW |
| Answer» D. 50,000 kW | |
| 93. |
A horizontal shaft centrifugal pump lifts water 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: |
| A. | 24 |
| B. | 26 |
| C. | 28 |
| D. | 30 |
| Answer» D. 30 | |
| 94. |
A turbine is called impulse turbine, if at the inlet of the turbine |
| A. | The total energy is only kinetic energy |
| B. | The total energy is only pressure energy |
| C. | The total energy is the sum of kinetic energy and pressure energy |
| D. | None of the above |
| Answer» B. The total energy is only pressure energy | |
| 95. |
In a reaction turbine, the draft tube is used to |
| A. | transport water to downstream without eddies |
| B. | reconvert kinetic energy to flow energy by a gradual expansion of the flow cross-section |
| C. | increase the effective head |
| D. | prevent air from entering |
| Answer» C. increase the effective head | |
| 96. |
In a pump there is |
| A. | accelerating flow |
| B. | decelerated flow |
| C. | either of above |
| D. | none of the above |
| Answer» B. decelerated flow | |
| 97. |
Cavitation begins when |
| A. | The pressure is increased rapidly |
| B. | The Flow is increased suddenly |
| C. | The pressure becomes more than the critical pressure |
| D. | The pressure falls below its vapour pressure and sudden bursting the bubble in high pressure zone |
| Answer» E. | |
| 98. |
A high head of water is required for |
| A. | Francis turbine |
| B. | Propeller turbine |
| C. | Pelton wheel |
| D. | Kaplan turbine |
| Answer» D. Kaplan turbine | |
| 99. |
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 power developed is: |
| A. | 7.5 kW |
| B. | 15.0 kW |
| C. | 22.5 kW |
| D. | 37.5 kW |
| Answer» D. 37.5 kW | |
| 100. |
Flow ratio for a Kaplan Turbine is given as 0.6 and the head available is 20 meter. Which of the following will be the approximate velocity of flow at the inlet of the runner? |
| A. | 9 m/sec |
| B. | 12 m/sec |
| C. | 15 m/sec |
| D. | 18 m/sec |
| Answer» C. 15 m/sec | |