# Gas Turbines Questions and Answers – Types, Engine and Component – 1

This set of Steam and Gas Turbines Multiple Choice Questions & Answers (MCQs) focuses 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

Explanation: 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

Explanation: 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
c) For standby application
d) For locomotive application

Explanation: 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

Explanation: 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

Explanation: Regenerators act as heat exchangers that heat the air before it enters the combustion chambers through exhaust gas emitting from exhaust cone.
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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

Explanation: 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

Explanation: 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

Explanation: PVk=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

Explanation: 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

Explanation: Titanium has best high temperature resistance and is almost unreactive even at elevated temperatures.

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