Category: Steam and Gas Turbines Objective Questions

Steam and Gas Turbines Multiple Choice Questions on “Dimensionless Performance Parameters”.

1. Dimensional analysis can be used to compare gas turbines.
a) True
b) False
Answer: a
Clarification: Dimensionless analysis can be used to compare gas turbines.

2. Reynolds number is a __________ parameter.
a) constant
b) have dimension
c) dimensionless constant
d) none of the mentioned
Answer: c
Clarification: Reynolds number is a dimensionless parameter.

3. Power is expressed in ___________
a) Horsepower
b) Volts
c) Ohms
d) None of the mentioned
Answer: a
Clarification: Power is expressed in horsepower.

4. Flow coefficient has no _______
a) value
b) dimension
c) flow coefficient is constant
d) none of the mentioned
Answer: b
Clarification: Flow coefficient has no dimension.

5. Pressure coefficient has ___________
a) no value
b) dimension
c) no dimension
d) none of the mentioned
Answer: c
Clarification: Pressure when expressed in dimensionless parameter is called as pressure coefficient.

6. ____________ when expressed in the form of dimensionless quantity is known as flow coefficient.
a) Flow rate
b) Pressure
c) Flow rate & Pressure
d) None of the mentioned
Answer: a
Clarification: Flow coefficient is a dimensionless quantity.

7. Mach number is a _________ parameter.
a) valued
b) dimensionless
c) valued & dimensionless
d) none of the mentioned
Answer: b
Clarification: Mach number is a dimensionless parameter.

8. Gas constants are classified under ________ dimension groups.
a) quasi
b) uni
c) multiple
d) none of the mentioned
Answer:a
Clarification: Gas constants are classified under quasi dimension groups.

9. Corrected groups are __________ proportional to quasi dimension groups.
a) inversely
b) directly
c) not related
d) none of the mentioned
Answer: b
Clarification: Corrected groups are directly proportional to quasi dimensional groups.

10. Working fluid properties are present in scaling parameter groups.
a) True
b) False
Answer: b
Clarification: Working fluid properties are not present in scaling parameter groups.

Basic Gas Turbines Interview questions and answers on “Fuels Used in Gas Turbines”.

1. _______ can be used as fuels in gas turbines.
a) Natural gases
b) petroleum
c) Diesel
d) All of the mentioned
Answer: d
Clarification: Natural gases,petrol,diesel etc can be used as fuels in gas turbines. Gas turbines requires liquids with high specific heat as fuels.

2. Vanadium content in the fuels used for gas turbines should be ________
a) high
b) low
c) zero
d) none of the mentioned
Answer: b
Clarification: Vanadium content must be low in the fuels used for gas turbines. Excessive vanadium content in the fuel leads to decrease in the specific heat of the fuel.

3. Fuels used in gas turbines should have _____ ash content.
a) low
b) high
c) zero
d) none of the mentioned
Answer: a
Clarification: Fuels used in gas turbines should have low ash content. When ash content is more calorific value of fuel gets decreased.

4. Gas turbine fuels congeal at __________ degrees are used in Locomotives.
a) -20
b) -10
c) -5
d) -15
Answer: c
Clarification: Gas turbine fuels congeal at -5 degrees are used in locomotives. Congealing temperature is the temperature at which the fuel freezes.

5. Fuels that congeal at ____________ degrees are used in automobiles.
a) -12
b) -15
c) -20
d) -15
Answer: a
Clarification: Fuels that congeal at -12 degrees are used in automobiles. Fuels used in gas turbines in automobiles has a freezing point of -12 degrees.

6. ______ oil can also be used to operate gas turbine power plants.
a) Leaded
b) Non leaded
c) Crude fuel
d) None of the mentioned
Answer:c
Clarification: Crude fuel oil can also be used to operate gas turbine power plants. Crude oil is the unrefined petroleum.

7. Water soluble salts are also removed from the fuels used in gas turbines.
a) True
b) False
Answer: a
Clarification: Water soluble salts are also removed from the fuels used in gas turbines. If the salts are not removed there is a chance for surge formation.

8. lead content must be ______ in gas turbine fuels.
a) high
b) low
c) zero
d) none the mentioned
Answer: b
Clarification: Lead content must be low in gas turbine fuels. If the lead content is increased it decreases the calorific value of the fuel.

9. Power loss will be _____ if impurities are present in gas turbine.
a) zero
b) less
c) high
d) none of the mentioned
Answer: c
Clarification: If impurities are present in fuel it consumes much heat to start combustion and hence power loss takes place.

10. Inhibitors are added to attack the ash developed by combustion of vanadium in gas turbine fuels.
a) True
b) False
Answer: a
Clarification: Inhibitors are added to attack the ash developed by combustion of vanadium in gas turbine fuels. Inhibitors reacts with vanadium and make them easy combustible during combustion.

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Steam and Gas Turbines Multiple Choice Questions on “Types, Engine and Component – 1”.

1. Pankaj watches a jet in air with a long trail of exhaust gas at its rear. What type of engine do they run on?
a) Prop Jet
b) Back Pressure Gas Turbine
c) Jet Propulsion Gas Turbine
d) Steam turbine
Answer: d
Clarification: Jet propulsion turbine provides high velocity and comfortable flight at very high altitudes.

2. Arrange the words to make a meaningful order: diffuser/exhaust cone/combustor/low pressure compressor/turbine/intercooler/high pressure compressor.
a) low pressure compressor/ turbine/ intercooler/ diffuser/ combustor/ high pressure compressor/ exhaust cone
b) diffuser/ low pressure compressor/ intercooler/ high pressure compressor/ combustor/ turbine/ exhaust cone
c) diffuser/ high pressure compressor/ intercooler/ low pressure compressor/ combustor/ turbine/ exhaust cone
d) combustor/ low pressure compressor/ turbine/ intercooler/ exhaust cone/ high pressure compressor/ diffuser
Answer: c
Clarification: Sequence of components in a Gas Turbine power plant.

3. Oil refineries seek significant application of gas turbine in which form?
a) They utilize waste hot gas from Houdry Cracking Process in order to drive a compressor
b) For peak load application
c) For standby application
d) For locomotive application
Answer: a
Clarification: The waste gas from the process have enough energy to operate a gas turbine which is used to drive a compressor supplying compressed air for the houdry process.

4. Indian Railways has 2000 HP coal burning units(locomotive wagon) with their efficiency as 20%. Calorific value of coal is 30,000 KJ/Kg. Find mass of coal required per hp-sec?
a) 0.2486kg/s
b) 0.1110kg/s
c) 0.3568kg/s
d) 0.2254kg/s
Answer: a
Clarification: Efficiency = work/heat supplied. Work is 2000 hp and heat supplied is mass flow rate * calorific value.

5. Engineers design a Gas Turbine Power Plant. Since the plant initial cost is too high, therefore engineers think to remove the regenerator from their original design. Then, the immediate consequence of the same would be?
a) Compressor work will increase
b) Combustor will require more fuel
c) Turbine will produce more work output per unit of fuel
d) Requirement of Intercooler to compensate for its loss
Answer: b
Clarification: Regenerators act as heat exchangers that heat the air before it enters the combustion chambers through exhaust gas emitting from exhaust cone.

6. Near a natural gas deposits, we require to set up a gas turbine plant. Geologist inform engineers that helium gas is found in abundance here. Hence, engineers seek to use helium as working medium for the gas power plant. This turbine is a _________
a) Multi-shaft open cycle gas turbine
b) Single shaft open cycle gas turbine
c) Closed cycle gas turbine
d) Simple Open cycle Gas Turbine
Answer: c
Clarification: Since the working fluid is other than air, therefore the plant is closed cycle gas turbine.

7. In order to generate energy in Sahara Desert where water is available in significantly low amount. Which system can we employ in such a place?
a) Steam Turbine
b) Gas Turbine
c) Steam Engine
d) Tidal Engine
Answer: b
Clarification: As gas turbine require very little or no water at all for their functioning.

8. Fresh air at 14.7psi enters a compressor of a gas turbine and is compressed isentropically. The gas at the mouth of turbine is at 60 psi pressure and with a specific volume as 50 m³/kg. What would be the specific volume of fresh air?
a) 136.54m³/kg
b) 125.64m³/kg
c) 126.54m³/kg
d) 135.64m³/kg
Answer: a
Clarification: PV^k=constant for isentropic process.

9. Assertion: Twin shaft arrangement of gas turbine must consist of two shafts whether in series or parallel.
Reason: In multi shaft arrangement two or more turbine-compressor combinations are carried on independent shafts. Select the most appropriate options following.
a) Both assertion and reason are correct and reason precisely explains the assertion
b) Both assertion and reason are correct but reason doesn’t exactly explains the assertion
c) Assertion is correct whilst reason is incorrect
d) Assertion is incorrect whilst reason is correct
Answer: d
Clarification: Single shaft arrangement must have all compressors and turbines to be coupled in a series arrangement.

10. The presence of high temperature conditions often limit the use of materials in the plant. Can you predict which of the options would be most suitable material for the gas turbine components?
a) Mn-Ni Alloy
b) Ti-Al-Sn-Zr Alloy
c) Stainless steel
d) Cast Iron
Answer: b
Clarification: Titanium has best high temperature resistance and is almost unreactive even at elevated temperatures.

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Steam and Gas Turbines Multiple Choice Questions on “Combined effect of intercooling, reheating and regeneration”.

1. Regenerator is also called as ___________
a) Intercooler
b) Reheater
c) Recuperator
d) None of the mentioned

Answer: c
Clarification: Regenerator is also called as a recuperator.

2. When recuperator is used thermal efficiency is ______
a) decreased
b) increased
c) doesn’t change
d) none of the mentioned

Answer: b
Clarification: When regenerator is used thermal efficiency is increased.

3. Inlet temperature of regenerator is __________
a) same as of the inlet exhausted gases
b) more than the inlet exhausted gases
c) less than the inlet exhaust gases
d) none of the mentioned

Answer: a
Clarification: Inlet temperature of regenerator is same as of inlet exhaust gases.

4. Effectiveness can be defined as _________
a) decrease in exhausted gases
b) inverse of the efficiency
c) ratio of heat rate to the mass entering
d) ratio of Actual heat transferred to the maximum heat transferred

Answer: d
Clarification: Effectiveness is the ratio of actual heat transferred to maximum heat that can be transferred.

5. Generally effectiveness of regenerators are ___________
a) 0.95
b) 0.66
c) 0.77
d) 0.85

Answer: d
Clarification: Generally effectiveness is 0.85 for a regenerator.

6. Compression can be taken place by _____________
a) isoentropic compression
b) isothermal compresion
c) two stage compression process
d) all of the mentioned

Answer: d
Clarification: Compression can be taken place by isoentropic compression or isothermal compression or by two stage compression.

7. Isoentropic compression requires maximum work.
a) True
b) False

Answer: a
Clarification: Isoentropic compression requires maximum work.

8. Isothermal compression requires minimum work.
a) True
b) False

Answer: a
Clarification: Isothermal compression requires minimum work.

9. By two stage compression work output from turbine is _______
a) decreased
b) increased
c) remains constant
d) none

Answer: b
Clarification: Two stage compression increases work output from turbine.

10. When equal pressure ratio are maintained at two stages the work output _______
a) increases
b) decreases
c) optimum
d) none of the mentioned

Answer: a
Clarification: When equal pressure ratio is maintained work output increases.

Steam and Gas Turbines Multiple Choice Questions on “Disk Stresses and Blade Fastening”.

1. Rotating disks are subjected to _______
a) mechanical stress
b) thermal stress
c) mechanical & thermal stress
d) none of the mentioned
Answer: c
Clarification: Rotating disks are subjected to both mechanical and thermal stresses.

2. Internal pressure on the disk are due to _______
a) broken fittings
b) expanded fittings
c) shrink fitted on its mountings
d) none of the mentioned
Answer: c
Clarification: Internal pressure on disk is caused due to shrink fitted on its mountings.

3. Finite element analysis is done for rotating disk.
a) True
b) False
Answer: a
Clarification: Different temperatures are established when hot gasses are passed and hence finite element analysis is done.

4. High stresses in rotating disks are caused due to _______
a) excessive temperature
b) excessive rotating speeds
c) excessive temperature & rotating speeds
d) none of the mentioned
Answer: b
Clarification: High stresses in rotating disks are caused due to excessive rotating speeds.

5. Rotational disks deform due to ______________
a) uni symmetrical
b) multi symmetrical
c) axi symmetrical
d) none of the mentioned
Answer: c
Clarification: Deformation of rotational disks is axi symmetrical.

6. Gas turbine discs are made of _______
a) Chromium
b) Chrome-Nickel steel alloy
c) Nickel
d) None of the mentioned
Answer: b
Clarification: Chrome-nickel steel alloy is used to make gas turbine discs in general.

7. Contact at fastening between blade root and disk staple is ________
a) one dimensional
b) two dimensional
c) three dimensional
d) none of the mentioned
Answer: c
Clarification: Three dimensional contact is maintained at fastening between blade root and disk staple.

8. Some of the fasteners are _______
a) Bolts
b) Nuts
c) Keys
d) All of the mentioned
Answer: d
Clarification: Keys, Nuts and Bolts are some fasteners in turbine generator steam turbines.

9. ________ are used to secure some fasteners which have tendency to slip or slide away.
a) Bolts
b) Nuts
c) Washers
d) None of the mentioned
Answer: c
Clarification: Washers are used to lock fasteners which slip or slide away.

10. Bolts are _______ fasteners.
a) locking fasteners
b) threaded fasteners
c) frictional fastener
d) none of the mentioned
Answer: b
Clarification: Bolts are threaded fasteners as they have threading on them.

Steam and Gas Turbines Multiple Choice Questions on “Pressure Regulators”.

1. Gas pressure regulators are also used to measure flow rates.
a) True
b) False
Answer: b
Clarification: Gas pressure regulators are used to regulate gas pressure and not to measure flow rates. Flow meter, rotameter, etc are used to measure the flow rates.

2. In pressure regulators load flow is ___________ proportional to regulator flow.
a) directly
b) indirectly
c) depends
d) none
Answer: a
Clarification: In pressure regulators if load flow increases regulator flow should also increase i.e load flow is directly proportional to regulator flow.

3. A pressure regulator consists of __________
a) Restricting element
b) Loading element
c) Measuring element
d) All of the mentioned
Answer: d
Clarification: Pressure regulator consists of a restricting element, a loading element, and a measuring element.

4. Restricting element in a pressure regulator can be _________
a) Globe valve
b) Poppet valve
c) Butterfly valve
d) All of the mentioned
Answer: d
Clarification: Restricting the element of a pressure regulator is a valve. It can be a globe valve or poppet valve or butterfly valve.

5. Diaphragm actuator can be used as loading element.
a) True
b) False
Answer: a
Clarification: Loading element is something that bears force. Diaphragm actuator can also be used as loading element.

6. Loading element in the pressure regulator can be ______
a) Spring
b) Weight
c) Piston actuator
d) All of the mentioned
Answer: d
Clarification: Loading element is something that provides necessary force to the restricting element.

7. The measuring element _______________
a) Measures the inlet flow
b) Measures the outlet flow
c) Compares the inlet flow to the outlet flow
d) None of the mentioned
Answer: c
Clarification: Measuring element is used to determine when the inlet flow is equal to outlet flow.

8. Diaphragm can be used as ___________
a) measuring element
b) combining element
c) measuring & combining element
d) none of the mentioned
Answer: d
Clarification: Diaphragm can also be used as measuring element. It can be used as combined element.

9. Pressure regulators can be used in _______
a) Air compressors
b) Aircraft
c) Aerospace
d) All of the mentioned
Answer: d
Clarification: Pressure regulators are used where the pressure needs to be regulated according to the inlet flow.

10. _____________ are used in gas powered vehicles.
a) pressure regulators
b) temperature regulators
c) pressure & temperature regulators
d) none of the mentioned
Answer: a
Clarification: Pressure regulators are used in gas powered vehicles as the stored gas is needed to bring to the operating pressure from a high pressure of about 700 bar.