McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 101. |
pump? |
| A. | cost |
| B. | simple in construction |
| C. | efficiency |
| D. | pump parameters |
| Answer» B. simple in construction | |
| Explanation: the major advantage of the centrifugal pump is that it has got a simple construction when compared to other types of centrifugal pumps. | |
| 102. |
Different velocities in a centrifugal pump are determined by using |
| A. | velocity triangle |
| B. | reynolds number |
| C. | froude number |
| D. | overall efficiency |
| Answer» A. velocity triangle | |
| Explanation: different velocities in a centrifugal pump are determined by using velocity triangle. this is an important triangle that determines the way the pump works. | |
| 103. |
Due to its impeller action, centrifugal pumps can cover a wide range of fluid pump applications. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: due to its impeller action, centrifugal pumps can cover a wide range of fluid pump applications. thus, the impeller action plays an important role. | |
| 104. |
With the increase in the input power, efficiency |
| A. | increases |
| B. | decreases |
| C. | same |
| D. | independent |
| Answer» B. decreases | |
| Explanation: with the increase in the input power, efficiency decreases. as the input power is inversely proportional to the efficiency of the pump. | |
| 105. |
What is unit of standard acceleration? |
| A. | kg/m |
| B. | kg/s |
| C. | kg/m3 |
| D. | n/m |
| Answer» C. kg/m3 | |
| Explanation: the unit of standard acceleration of the centrifugal pump is kg/m3. it is denoted as g. it is also called as the acceleration due to gravity. | |
| 106. |
What does PSP stand for? |
| A. | pump start procedure |
| B. | positive start pump |
| C. | pump start pointer |
| D. | positive start pointer |
| Answer» A. pump start procedure | |
| Explanation: psp stands for pump start procedure. it is the basic method to start the pump by lining up the pump valves in a sequence by ensuring that the drain valve is closed. | |
| 107. |
Centrifugal pump is a |
| A. | turbomachinery |
| B. | flow regulating device |
| C. | drafting device |
| D. | intercooling device |
| Answer» A. turbomachinery | |
| Explanation: centrifugal pump is a turbomachinery. turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. it is a mechanical device. | |
| 108. |
Turbomachines work under |
| A. | newtons first law |
| B. | newtons second law |
| C. | newtons third law |
| D. | kepler’s law |
| Answer» B. newtons second law | |
| Explanation: turbomachines work under newtons second law. centrifugal pump is a turbomachinery. turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. it is a mechanical device. | |
| 109. |
The main function of nozzle is to |
| A. | varying temperatures |
| B. | pressure variations |
| C. | load variations |
| D. | heat variations |
| Answer» B. pressure variations | |
| Explanation: the main function of nozzle is to vary the pressure of fluid passing through the nozzle. it is done by opening and shutting the sets of nozzles. thus, its main function is to regulate pressure of the fluid. | |
| 110. |
The main function of centrifugal pumps are to |
| A. | transfer speed |
| B. | transfer pressure |
| C. | transfer temperature |
| D. | transfer energy |
| Answer» D. transfer energy | |
| Explanation: the primary objective of a centrifugal pump is to transfer energy. | |
| 111. |
Centrifugal pumps transfer energy from |
| A. | rotor to fluid |
| B. | fluid to rotor |
| C. | draft to rotor |
| D. | rotor to draft |
| Answer» A. rotor to fluid | |
| Explanation: centrifugal pumps transfer energy from rotor to fluid. the primary objective of a centrifugal pump is to transfer energy. centrifugal pump is a turbomachinery. | |
| 112. |
controlled by |
| A. | head race |
| B. | gate |
| C. | tail race |
| D. | pump |
| Answer» B. gate | |
| Explanation: the inlet passage of water entry is controlled by the gate opening. the gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine. | |
| 113. |
Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: the statement is true. centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. the main function of centrifugal pumps are to transfer energy. | |
| 114. |
Turbines and compressors work with the gas, while centrifugal pump transfers energy. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: turbines and compressors work with the gas, while centrifugal pump transfers energy. centrifugal pumps transfer energy from rotor to fluid. the primary objective of a centrifugal pump is to transfer energy. | |
| 115. |
Centrifugal pump is a turbomachinery. |
| A. | pressure |
| B. | speed |
| C. | power |
| D. | fluid |
| Answer» D. fluid | |
| Explanation: centrifugal pumps are used to transport fluids. they transport fluids by conversion of energies. centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. | |
| 116. |
Centrifugal pumps transport fluids by converting |
| A. | kinetic energy to hydrodynamic energy |
| B. | hydrodynamic energy to kinetic energy |
| C. | mechanical energy to kinetic energy |
| D. | mechanical energy to hydrodynamic energy |
| Answer» A. kinetic energy to hydrodynamic energy | |
| Explanation: centrifugal pumps are used to transport fluids. they transport fluids by conversion of energies. centrifugal pumps transport fluids by converting rotational kinetic energy to hydrodynamic energy. | |
| 117. |
With the increase in load, Energy in the turbine |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | independent |
| Answer» A. decreases | |
| Explanation: when there is an increase in the load, the energy in the turbine is drained off. | |
| 118. |
The rotational kinetic energy comes from |
| A. | engine motor |
| B. | pump |
| C. | tank |
| D. | draft tube |
| Answer» A. engine motor | |
| Explanation: centrifugal pumps transport fluids by converting rotational kinetic energy to hydrodynamic energy. the rotational kinetic energy comes from engine or electrical motor. | |
| 119. |
When the balancing of the turbine is disturbed, we use |
| A. | throttle governing |
| B. | steam governing |
| C. | nozzle governing |
| D. | emergency governing |
| Answer» D. emergency governing | |
| Explanation: when the balancing of the turbine is disturbed, we use emergency governing. these governors come into action | |
| 120. |
The fluid coming into the centrifugal pump is accelerated by |
| A. | throttle |
| B. | impeller |
| C. | nozzle |
| D. | governor |
| Answer» B. impeller | |
| Explanation: the fluid coming into the centrifugal pump is accelerated by an impeller. the fluid enters the pump along a radially outward direction into the diffuser or a volute chamber. | |
| 121. |
Reciprocating pump is a |
| A. | negative displacement pump |
| B. | positive displacement pump |
| C. | diaphragm pump |
| D. | emulsion pump |
| Answer» B. positive displacement pump | |
| Explanation: reciprocation pump is a type of positive displacement pump. it has a piston pump, plunger and diaphragm. reciprocating pumps have a good life provided that they are not left untouched. | |
| 122. |
What happens to the reciprocating pump when left untouched? |
| A. | efficiency decreases |
| B. | wear and tear |
| C. | surface expansion |
| D. | pressure change |
| Answer» C. surface expansion | |
| Explanation: when left untouched over a period of time, the reciprocating pump undergoes wear and tear. reciprocating pumps have a good life provided that they are not left untouched. | |
| 123. |
into the chamber |
| A. | liquid |
| B. | pressure |
| C. | heat |
| D. | electricity |
| Answer» A. liquid | |
| Explanation: reciprocating pumps operate by drawing liquid into the chamber or the cylinder with the help of a piston. | |
| 124. |
The cylinder of reciprocating cylinder is made up of |
| A. | cast iron |
| B. | wrought iron |
| C. | aluminium |
| D. | copper |
| Answer» A. cast iron | |
| Explanation: the cylinder of reciprocating cylinder is made up of cast iron. sometimes it is also made of steel alloy. the movement of piston is obtained by a connecting rod which connects piston and rotating crank inside the cylinder. | |
| 125. |
The higher discharge valve line holds the discharge valve |
| A. | open |
| B. | closed |
| C. | stop functioning |
| D. | automatic |
| Answer» B. closed | |
| Explanation: the higher discharge valve line holds the discharge valve closed. this helps in maintaining the valve safely. | |
| 126. |
Reciprocating pumps are classified according to |
| A. | drag force |
| B. | number of cylinders |
| C. | shock waves |
| D. | flow speed |
| Answer» B. number of cylinders | |
| Explanation: reciprocating pumps are classified according to the number of cylinders. and also it classified according to the number of piston sides. | |
| 127. |
Simple hand operating pump is also called as |
| A. | froth pump |
| B. | bicycle pump |
| C. | multistage pumps |
| D. | centrifugal pumps |
| Answer» B. bicycle pump | |
| Explanation: simple hand operating pump is also called as bicycle pumps. it is the simplest pump that is used to inflate bicycle tires and various sporting balls. | |
| 128. |
Internal cavitation in reciprocating pumps occurs due to |
| A. | drag force |
| B. | cyclic stress |
| C. | shock waves |
| D. | flow speed |
| Answer» C. shock waves | |
| Explanation: at high pressure, the voids can generate shock waves. cavitation usually occurs due to the changes in pressure. the pressure change is so rapid that it leads to formation of liquid free layers or cavities that start to affect the overall performance. | |
| 129. |
Bicycle pump generates more compression than volume displacement. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: bicycle pump generates more compression than volume displacement. | |
| 130. |
Power operated pump in which only one side engages the fluid displacement is called |
| A. | froth pump |
| B. | single acting |
| C. | double acting |
| D. | bicycle pump |
| Answer» B. single acting | |
| Explanation: power operated pump in which only one side engages the fluid displacement is called as single acting reciprocating pump. it consists of piston in only one side of the fluid being displaced. | |
| 131. |
Operation of reciprocating motion is done |
| A. | froth pump |
| B. | single acting |
| C. | double acting |
| D. | bicycle pump |
| Answer» C. double acting | |
| Explanation: power operated pump in which both the side engages the fluid displacement is called as double acting reciprocating pump. it consists of piston in both the side of the fluid being displaced. | |
| 132. |
has higher specific speed than the others? |
| A. | axial flow |
| B. | radial flow |
| C. | mixed flow |
| D. | all centrifugal pumps have same specific speed |
| Answer» A. axial flow | |
| Explanation: an axial flow pump is a type of centrifugal pump that uses an impeller with vanes that direct the flow axially. axial flow | |
| 133. |
pump is also called as |
| A. | reciprocating pump |
| B. | rotary displacement pump |
| C. | centrifugal pump |
| D. | none of the mentioned |
| Answer» C. centrifugal pump | |
| Explanation: centrifugal pump is not a positive displacement pump. reciprocating pumps move liquid by means of a constant back-and-forth motion of a piston, plunger, or diaphragm within a fixed volume or cylinder. reciprocating pumps can handle viscous and | |
| 134. |
Which pump is more suitable for an application where very high pressure is required to be developed at moderate discharge? |
| A. | reciprocating pump |
| B. | centrifugal pump |
| C. | turbine |
| D. | none of the mentioned |
| Answer» A. reciprocating pump | |
| Explanation: reciprocating pumps are generally designed to pump in low flow, high head applications. one of the most extreme of these applications is water jet cutting, where only a few gallons pass through the pump per minute, but exceed pressures of 10,000 psi. | |
| 135. |
The process of filling the liquid into the suction pipe and pump casing up to the level of delivery valve is called as |
| A. | filling |
| B. | pumping |
| C. | priming |
| D. | leveling |
| Answer» C. priming | |
| Explanation: most pumps are not self- priming. in other words, the pump casing must be filled with liquid before the pump is started, or the pump will not be able to function. in case the pump casing gets filled with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping. | |
| 136. |
Most widely used sanitary pumps in the dairy industry are? |
| A. | centrifugal pump |
| B. | liquid ring pump |
| C. | positive displacement pump |
| D. | suction pump |
| Answer» A. centrifugal pump | |
| Explanation: typical dairy pumps are the centrifugal, liquid-ring and positive displacement pumps. the three types have different applications. the centrifugal pump is the type most widely used in dairies. | |
| 137. |
Main application of centrifugal pump is in which of the following? |
| A. | low viscosity products |
| B. | heavily aerated liquids |
| C. | gentle treatment with high viscosity |
| D. | water treatment |
| Answer» A. low viscosity products | |
| Explanation: the centrifugal pump can be used for pumping of all liquids of relatively low viscosity which do not require particularly gentle treatment. it can also be used for liquids containing relatively large particles, provided of course that the particle size does not exceed the dimensions of the impeller channel. | |
| 138. |
Main application of positive displacement pump is in which of the following? |
| A. | low viscosity products |
| B. | heavily aerated liquids |
| C. | gentle treatment with high viscosity |
| D. | water treatment |
| Answer» C. gentle treatment with high viscosity | |
| Explanation: this type of pump has 100% volumetric efficiency (no slip) when the viscosity exceeds approximately 300 cp. because of the sanitary design and the gentle treatment of the product, this type of pump is widely used for pumping cream with a high fat content, cultured milk products, curd/whey mixtures, etc. | |
| 139. |
Which of the following pump suitable for handling AMF in the dairy industry? |
| A. | centrifugal pump |
| B. | liquid ring pump |
| C. | diaphragm pump |
| D. | peristaltic pumps |
| Answer» D. peristaltic pumps | |
| Explanation: in peristaltic pumps, during rotation, the medium (liquid or gas) inside the hose is transported to the lower outlet connection. this creates a vacuum on the suction side, and the product is drawn into the pump. the pump is self-priming and is therefore suitable for emptying barrels with juice concentrates and anhydrous milk fat (amf). | |
| 140. |
runner in a Francis turbine? |
| A. | axial and then tangential |
| B. | tangential and then axial |
| C. | radial and then axial |
| D. | axial and then radial |
| Answer» C. radial and then axial | |
| Explanation: francis turbine is radial flow reaction turbine. though the water enters the turbine tangentially, it enters the runner radially inward and flows outward along the axis of the runner. | |
| 141. |
Which of the following is true in case of flow of water before it enters the runner of a Francis Turbine? |
| A. | available head is entirely converted to velocity head |
| B. | available head is entire converted to pressure head |
| C. | available head is neither converted to pressure head nor velocity head |
| D. | available head is partly converted to pressure head and partly to velocity head |
| Answer» D. available head is partly converted to pressure head and partly to velocity head | |
| Explanation: since francis turbine is a reaction turbine, part of the available head is converted to velocity head. it is not entirely converted to velocity head. the rest of the available head is converted into pressure head. | |
| 142. |
Which of the following profiles are used for guide vanes to ensure smooth flow without separation? |
| A. | rectangular |
| B. | bent rectangular |
| C. | elliptical |
| D. | aerofoil |
| Answer» D. aerofoil | |
| Explanation: smooth flow and flow without separation (eddiless flow) can be ensured when the cross sectional profile of the guide vanes are aerofoil in nature. aerofoil shape is used in airplane wings to ensure smooth flow too. rectangular profiles are not effective in guiding the water into the runner. elliptical profiles will cause more drag, finally ending up with turbine inefficiency. | |
| 143. |
In which of the following type of runners the velocity of whirl at inlet is greater than the blade velocity? |
| A. | such a case is practically impossible |
| B. | slow runner |
| C. | medium runner |
| D. | fast runner |
| Answer» B. slow runner | |
| Explanation: considering the velocity diagram of francis turbine at the inlet for a slow runner, we notice that the whirl velocity exceeds the blade velocity along the same direction. they are equal in case of a medium runner. | |
| 144. |
have the highest vane angle at inlet (β1 value)? |
| A. | slow runner |
| B. | medium runner |
| C. | fast runner |
| D. | vane angle is defined only for kaplan turbines and not francis turbines |
| Answer» C. fast runner | |
| Explanation: considering the velocity diagram of francis turbine at the inlet for a fast runner, vane angle is an obtuse angle. whereas, it is right angle for medium runner and an acute angle for a slow runner. | |
| 145. |
In case of a Medium runner, tan (α1) CANNOT be given by (α1 = Guide vane angle at inlet)? |
| A. | vf1 / vw1 |
| B. | vr1 / vw1 |
| C. | vr1 / u1 |
| D. | vw1 / u1 |
| Answer» D. vw1 / u1 | |
| Explanation: in medium runner, vf1 = vr1 & vw1 = u1. vw1 and u1 are along the same direction, hence that cannot be written as tan (α1). | |
| 146. |
In the velocity diagrams for Francis turbine, which of the following velocity directions is along the blade curvature? |
| A. | vr1 |
| B. | vw1 |
| C. | v1 |
| D. | u1 |
| Answer» A. vr1 | |
| Explanation: vr1 is the relative velocity of the water flow as seen from the blade. thus, relative velocity is along the direction of the curvature of the blade. | |
| 147. |
TOPIC 5.2 AXIAL, RADIAL AND MIXED FLOW TURBINES. |
| A. | guide vane angle at inlet |
| B. | blade angle at inlet |
| C. | vane angle at inlet |
| D. | blade angle at outlet |
| Answer» A. guide vane angle at inlet | |
| Explanation: the angle between v1 and the blade velocity u1 is α1, which is the guide vane angle at the inlet. | |
| 148. |
In the figure shown below, which of the following type of runners has the blade curvature as shown in the above figure (The arrow denotes direction of blade motion)? |
| A. | information insufficient to determine |
| B. | slow runner |
| C. | medium runner |
| D. | fast runner |
| Answer» B. slow runner | |
| Explanation: fast runners have forward curved blades, where slow runners have backward curved blades. the blades shown in the figure are backward curved blades of a runner, which are used for slow runners. | |
| 149. |
category of |
| A. | energy absorbing machines |
| B. | energy generating machines |
| C. | power absorbing machines |
| D. | energy transfer machines |
| Answer» D. energy transfer machines | |
| Explanation: hydraulic coupling is a device used for transmitting rotation between shafts by means of acceleration and deceleration of hydraulic fluid. | |
| 150. |
The electric power which is obtained from hydraulic energy |
| A. | thermal power |
| B. | mechanical power |
| C. | solar power |
| D. | hydroelectric power |
| Answer» D. hydroelectric power | |
| Explanation: hydroelectric power is generated by using hydraulic machines. potential energy of water is converted to mechanical energy which is connected to dynamo to generate electrical energy. | |
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