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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.
| 151. |
An impulse turbine requires: |
| A. | high head and large quantity of flow |
| B. | high head and small quantity of flow |
| C. | low head and small quantity of flow |
| D. | low head and large quantity of flow |
| Answer» C. low head and small quantity of flow | |
| 152. |
For a Kaplan turbine, the value of the speed ratio is _________. |
| A. | 2 |
| B. | 0.5 |
| C. | 0.1 |
| D. | 0.9 |
| Answer» B. 0.5 | |
| 153. |
In a pump, the impeller is surrounded by spiral shaped casing which is known as __________. |
| A. | draft tube |
| B. | volute chamber |
| C. | guide vanes |
| D. | diffuser |
| Answer» C. guide vanes | |
| 154. |
If two pumps identical in all respects and each capable of delivering a discharge Q against a head H are connected in series, the resulting discharge is |
| A. | 2Q against a head 2H |
| B. | 2Q against a head H |
| C. | Q against a head 2H |
| D. | \(\sqrt Q\) against a head H |
| Answer» D. \(\sqrt Q\) against a head H | |
| 155. |
An inward flow reaction turbine has an external diameter of 1 m and its breadth at inlet is 250 mm. If the velocity of flow at inlet is 2 m/s and 10% of the area of flow is blocked by blade thickness, the weight of water passing through the turbine will be nearly |
| A. | 10 kN/s |
| B. | 14 kN/s |
| C. | 18 kN/s |
| D. | 22 kN/s |
| Answer» C. 18 kN/s | |
| 156. |
Impulse turbines work on the principle of |
| A. | Newton’s first law |
| B. | Newton’s second law |
| C. | Newton’s third law |
| D. | Conservation of mass |
| Answer» C. Newton’s third law | |
| 157. |
A centrifugal pump with peripheral speed ‘V’ was selected for a total lift of 100 m. Actually pump was to be operated for a total lift of 400 m. the peripheral speed should actually be (other conditions remaining same) |
| A. | 2 V |
| B. | 4 V |
| C. | 8 V |
| D. | 1 V |
| Answer» B. 4 V | |
| 158. |
For a given centrifugal pump, discharge varies ________ with speed. |
| A. | inversely |
| B. | linearly |
| C. | square root of |
| D. | fifth power of |
| Answer» C. square root of | |
| 159. |
Double hemispherical buckets are used in |
| A. | Kaplan Turbine |
| B. | Francis turbine |
| C. | Propeller turbine |
| D. | Pelton wheel turbine |
| Answer» E. | |
| 160. |
Pelton Wheel turbine is: ________. |
| A. | High head high discharge turbine |
| B. | High head low discharge turbine |
| C. | Low head high discharge turbine |
| D. | Low head low discharge turbine |
| Answer» C. Low head high discharge turbine | |
| 161. |
A single-acting reciprocating pump has a stroke of 25 cm, speed of 135 rpm, and a piston of 30 cm diameter. If its slip has been estimated as 4% at a particular operating condition, what is the corresponding realized discharge through a height of 14 m? |
| A. | 33.2 lps |
| B. | 35.6 lps |
| C. | 37.0 lps |
| D. | 38.2 lps |
| Answer» E. | |
| 162. |
For double acting reciprocating pump, there will be no flow into or from the air valve, when the crank angle is: |
| A. | 39° 32' and 140° 28' |
| B. | 39° 32 to 140° 28' |
| C. | 0° to 39° 32' |
| D. | 18° 34' to 161° 26' |
| Answer» B. 39° 32 to 140° 28' | |
| 163. |
Consider the following statements regarding reaction turbine:1. Blade shape is aerofoil type and its manufacturing is difficult.2. It is suitable for small power.3. Leakage losses are less compared to friction losses.Which of the above statements is/are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | 3 only |
| D. | 1, 2 and 3 |
| Answer» B. 2 only | |
| 164. |
In axial flow pumps and compressors, the combined velocity diagram with common base is used to determine change in |
| A. | absolute velocity (V2 – V1) |
| B. | relative velocity (Vr2 – Vr1) |
| C. | tangential velocity (U2 – U1) |
| D. | whirl velocity (Vu2 – Vu1) |
| Answer» E. | |
| 165. |
If the outlet angle of the bucket for Pelton wheel is 60°, the maximum efficiency in the case of Pelton wheel neglecting friction in the bucket is: |
| A. | 75% |
| B. | 80% |
| C. | 50% |
| D. | 90% |
| Answer» B. 80% | |
| 166. |
An impulse turbine |
| A. | requires draft tube |
| B. | is most suited for low head application |
| C. | operates by initial complete conversion to kinetic energy |
| D. | is not exposed to atmosphere |
| Answer» D. is not exposed to atmosphere | |
| 167. |
If the overall efficiency of a Pelton Turbine is 65% and its Mechanical efficiency is 80%, then its Hydraulic efficiency would be? |
| A. | 81.25% |
| B. | 55.25% |
| C. | 75.25% |
| D. | 85.25% |
| Answer» B. 55.25% | |
| 168. |
Draft tube for a reaction turbine is arranged for |
| A. | Safety purpose only |
| B. | Increasing velocity head |
| C. | Converting kinetic head into pressure head |
| D. | Diverting water only |
| Answer» D. Diverting water only | |
| 169. |
If at the inlet, only kinetic energy is available, then name the turbine. |
| A. | Impulse turbine |
| B. | Mixed-flow turbine |
| C. | Reaction turbine |
| D. | Low specific speed turbine |
| Answer» B. Mixed-flow turbine | |
| 170. |
Draft tube at the exit of a reaction turbine used for the hydroelectric project is __________. |
| A. | above or below the water surface, depends on unit speed of the turbine |
| B. | always above the water surface |
| C. | always immersed in water |
| D. | may either be below or above the water surface |
| Answer» D. may either be below or above the water surface | |
| 171. |
A jet of water issuing from a nozzle strikes a flat plate normally (plane of plate makes an angle 90° with the axis of the jet). The plate moves away from the nozzle with a velocity of 10 m/s while the jet issuing from the nozzle has a velocity of 15 m/s. The absolute velocity components of the jet (in m/s) after it strikes the plate, parallel (x component) and normal component (y component) to the undisturbed jet are. (Neglect friction on the surface). |
| A. | Vx = 5, Vy = 5 |
| B. | Vx = -5, Vy = 5 |
| C. | Vx = 10, Vy = 10 |
| D. | Vx = -10, Vy = 25 |
| Answer» B. Vx = -5, Vy = 5 | |
| 172. |
In a parson's reaction turbine, when α1 is the angle with the direction of motion of the blade at which steams enters the blade, then the maximum efficiency of the turbine is given by |
| A. | \(\frac{{2\cos \alpha_1 }}{{1 + \cos \alpha_1 }}\) |
| B. | \(\frac{{2{{\cos }^2}\alpha_1 }}{{1 + {{\cos }^2}\alpha_1 }}\) |
| C. | \(\frac{{2{{\cos }^2}\alpha_1 }}{{1 - \cos \alpha_1 }}\) |
| D. | \(\frac{{2{{\cos }^2}\alpha_1 }}{{1 + 2{{\cos }^2}\alpha_1 }}\) |
| Answer» C. \(\frac{{2{{\cos }^2}\alpha_1 }}{{1 - \cos \alpha_1 }}\) | |
| 173. |
Power required to drive a centrifugal pump is proportional to |
| A. | N |
| B. | N2 |
| C. | N3 |
| D. | N4 |
| Answer» D. N4 | |
| 174. |
In case of reaction turbine____ (where P stands for pressure) |
| A. | \({P_1} = {P_2}\) |
| B. | \({P_1} > {P_2}\) |
| C. | \({P_1} < {P_2}\) |
| D. | None of these |
| Answer» C. \({P_1} < {P_2}\) | |
| 175. |
A jet of water issues from a nozzle with a velocity of 20 m/s and it impinges normally on a flat plate moving away from it at 10 m/s. If the cross-sectional area of the jet is 0.02 m2 and the density of water is taken as 1000 kg/m3, then the force developed on the plate is |
| A. | 10 N |
| B. | 100 N |
| C. | 1000 N |
| D. | 2000 N |
| Answer» E. | |
| 176. |
A pump handling a liquid raises its pressure from 1 bar to 30 bar. Take the density of the liquid as 990 kg /m3 . The isentropic specific work done by the pump in kJ/kg is |
| A. | 0.10 |
| B. | 0.30 |
| C. | 2.50 |
| D. | 2.93 |
| Answer» E. | |
| 177. |
Pump commonly used for lifting water in water supply mains is |
| A. | axial-flow pump |
| B. | centrifugal pump |
| C. | reciprocating pump |
| D. | rotary – type pump |
| Answer» B. centrifugal pump | |
| 178. |
A commonly used handpump is the: |
| A. | Centrifugal pump |
| B. | Reciprocating pump |
| C. | Rotary pump |
| D. | Axial flow pump |
| Answer» C. Rotary pump | |
| 179. |
A centrifugal pump gives maximum efficiency when its blades are |
| A. | Bent forward |
| B. | Bent backward |
| C. | Straight |
| D. | Wave shaped |
| Answer» C. Straight | |
| 180. |
A Francis turbine has an overall efficiency of 83%. If it develops the power of 500 kW under a net head of 3000 cm, the discharge through the turbine in m3/s is: |
| A. | 2.50 |
| B. | 20.50 |
| C. | 25.0 |
| D. | 2.05 |
| Answer» E. | |
| 181. |
Impulse turbine is used for: |
| A. | Low head |
| B. | High head |
| C. | Medium head |
| D. | High flow |
| Answer» C. Medium head | |
| 182. |
A hydraulic turbine develops 5000 kW under a head of 30 m when running at 100 rpm. This turbine belongs to the category of |
| A. | Pelton wheel |
| B. | Francis Turbine |
| C. | Kaplan Turbine |
| D. | Propeller Turbine |
| Answer» C. Kaplan Turbine | |
| 183. |
A single-stage impulse turbine with a diameter of 120 cm runs at 3000 rpm. If the blade speed ratio is 0.42, then, the inlet velocity of steam will be |
| A. | 79 m/s |
| B. | 188 m/s |
| C. | 450 m/s |
| D. | 900 m/s |
| Answer» D. 900 m/s | |
| 184. |
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, Pelton |
| D. | Pelton, Kaplan, Francis |
| Answer» B. Pelton, Francis, Kaplan | |
| 185. |
In a Pelton wheel, jet ratio values are ______. |
| A. | less then 1 |
| B. | between 2 and 5 |
| C. | more then 6 |
| D. | less then or equal to 2 |
| Answer» D. less then or equal to 2 | |
| 186. |
Power required to drive a centrifugal pump is |
| A. | Directly proportional to speed of its impeller |
| B. | Directly proportional to square of the speed of its impeller |
| C. | Directly proportional to cube of the speed of its impeller |
| D. | Inversely proportional to cube of the speed of its impeller |
| Answer» D. Inversely proportional to cube of the speed of its impeller | |
| 187. |
In a half-degree reaction Parson’s turbine, operating at design conditions, the enthalpy drop of steam in one stage of the turbine occurs |
| A. | Entirely in the fixed blades |
| B. | Entirely in the moving blades |
| C. | Half in the fixed blades and half in the moving blades |
| D. | None of the above |
| Answer» D. None of the above | |
| 188. |
For a centrifugal water pump if flow rate if 36000 lit/hr and head added to flow is 10 m, calculate water horse power (WHP). |
| A. | 981 kW |
| B. | 9.81 kW |
| C. | 98.1 kW |
| D. | 0.981 kW |
| Answer» E. | |
| 189. |
An impulse turbine operating with a single nozzle has a specific speed of 5. What will be the approximate specific speed of the turbine if the turbine is operated with one more additional nozzle of the same size? |
| A. | 4 |
| B. | 6 |
| C. | 7 |
| D. | 10 |
| Answer» D. 10 | |
| 190. |
A turbine develops 7223 kW power under a bead of 25 m at 135 rpm. The specific speed of the turbine will be nearly |
| A. | 245 rpm |
| B. | 225 rpm |
| C. | 205 rpm |
| D. | 185 rpm |
| Answer» D. 185 rpm | |
| 191. |
Mainly hydraulic turbines are used to drive the electrical alternators which require maintaining the peripheral speed constant even at part load conditions to avoid the change in frequency of electric power. The governing of the hydraulic turbine is done by |
| A. | Controlling the flow area |
| B. | Controlling the velocity |
| C. | Using the fly wheel |
| D. | Combined control of flow area and velocity |
| Answer» B. Controlling the velocity | |
| 192. |
High lift multi-stage centrifugal pumps work against a head of: |
| A. | < 15 m |
| B. | 15 – 20 m |
| C. | 20 – 40 m |
| D. | >40 m |
| Answer» E. | |
| 193. |
Human heart is a ________ pump |
| A. | reciprocating |
| B. | positive displacement |
| C. | centrifugal |
| D. | None of these |
| Answer» C. centrifugal | |
| 194. |
Centrifugal pumps when arranged in parallel |
| A. | Increase the discharge only |
| B. | Increase both the discharge and head |
| C. | Increase the head only |
| D. | Increase the head but decrease the discharge |
| Answer» B. Increase both the discharge and head | |
| 195. |
For a reciprocating water pump having cylinder diameter d and crank radius r, if W is the weight of water lifted, the coefficient of discharge is |
| A. | \(\frac{W}{{\pi {d^2}r}}\) |
| B. | \(\frac{{2W}}{{\gamma \pi {d^2}r}}\) |
| C. | \(\frac{W}{{\gamma {d^2}r}}\) |
| D. | \(\frac{W}{{\gamma \pi {d^2}}}\) |
| Answer» C. \(\frac{W}{{\gamma {d^2}r}}\) | |
| 196. |
In all reaction turbine, maximum efficiency is obtained if the: |
| A. | blade angle is 90° at the inlet |
| B. | angle of absolute velocity vector at the outlet is 90° |
| C. | guide vane angle is 90° |
| D. | blade angle is 90° at the outlet |
| Answer» C. guide vane angle is 90° | |
| 197. |
Cavitation phenomenon can take place in |
| A. | Pelton turbine |
| B. | Reciprocating pump |
| C. | Centrifugal pump |
| D. | Tangential flow turbine |
| Answer» D. Tangential flow turbine | |
| 198. |
If the specific speed of turbine is more than 300, the type of turbine is- |
| A. | Pelton |
| B. | Kaplan |
| C. | Francis |
| D. | Pelton with nose jets |
| Answer» C. Francis | |
| 199. |
Match the items in column - 1 and column - 2 and choose the correct combinationColumn - 1 Column - 2K - Kaplan 1 - steam turbineP – Pearsons 2 – inward flow reactionFo - Fourneyron 3 – outward flow reactionFr – Francis 4 – Axial flow turbine |
| A. | K – 1, P – 4, Fo – 3, Fr – 3 |
| B. | K – 3, P – 1, Fo – 3, Fr – 2 |
| C. | K – 4, P – 1, Fo – 3, Fr – 2 |
| D. | K – 2, P – 4, Fo – 4, Fr – 2 |
| Answer» D. K – 2, P – 4, Fo – 4, Fr – 2 | |
| 200. |
For very high discharge at low pressure such as for flood control and irrigation applications, which of the following types of pump is preferred? |
| A. | Centrifugal |
| B. | Axial Flow |
| C. | Reciprocating |
| D. | Mixed Flow |
| Answer» C. Reciprocating | |