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Rockets

5 Questions
GATEโ†’2026โ†’Propulsionโ†’Rockets
Q75
NAT[2 Marks]
A centrifugal compressor has a constant-width radial diffuser. The diameters at the diffuser inlet and outlet are 0.2 m and 0.3 m, respectively. The flow at the diffuser inlet and outlet is assumed to be steady and uniform. The average velocity at the diffuser inlet and outlet are (60 ๐žฬ‚๐ซ + 75 ๐žฬ‚๐›‰ ) m/s and (๐‘ข ๐žฬ‚๐ซ + 50 ๐žฬ‚๐›‰ ) m/s, respectively. If the flow through the diffuser is treated as steady and incompressible, the value of ๐‘ข is ________ (rounded off to the nearest integer).
GATEโ†’2025โ†’Propulsionโ†’Rockets
Q76
NAT[1 Mark]
In a centrifugal compressor, the eye tip diameter is 10 cm. For a shaft rotational speed of 490 rotations per second, the tangential speed at the inducer tip is ___ m/s (rounded off to one decimal place).
GATEโ†’2023โ†’Propulsionโ†’Rockets
Q77
NAT[2 Marks]
A centrifugal air compressor has inlet root diameter of 0.25 m and the outlet diameter of the impeller is 0.6 m. The pressure ratio is 5.0. The air at the inlet of the rotor is at 1 atm and 25oC. The polytropic efficiency is 0.8 and slip factor is 0.92. Use C p = 1.004 kJ/kg-K and ๏ง= 1.4 . The impeller speed in revolutions per minute (RPM) is _________. (round off to the nearest integer)
GATEโ†’2022โ†’Propulsionโ†’Rockets
Q78
MCQ[1 Mark]
The region of highest static temperature in a rocket engine and the region of highest heat flux are respectively.
GATEโ†’2022โ†’Propulsionโ†’Rockets
Q79
MSQ[2 Marks]
A rocket operates at absolute chamber pressure of 20 bar to produce thrust F1F_1, optimally expanded with CF,1=1.42C_{F,1} = 1.42. Same rocket at 50 bar produces F2F_2 and CF,2C_{F,2}. Which statement(s) is/are correct?

Turbomachinery

10 Questions
GATEโ†’2026โ†’Propulsionโ†’Turbomachinery
Q37
MSQ[1 Mark]
The figure below shows the blading of the rotors of two different axial turbomachines under their typical operating conditions, labelled as Configuration I and Configuration II. Which of the following statements is/are TRUE?
Figure for Question 37
GATEโ†’2026โ†’Propulsionโ†’Turbomachinery
Q38
MSQ[1 Mark]
A multi-stage axial compressor can be operated at two points, A and B, both of which lie on the same speed line, as shown in the figure below. If ๐œ‚ is the isentropic efficiency of the compressor, select the statements that is/are TRUE.
Figure for Question 38
GATEโ†’2026โ†’Propulsionโ†’Turbomachinery
Q39
MCQ[2 Marks]
The figure below shows a compressor stage with station numbers 1, 2, and 3 as indicated. If ๐‘0๐‘– , ๐‘‡0๐‘– , and ๐ถ๐‘– refer to the average values of total pressure, total temperature, and absolute flow speed, respectively, at the ๐‘– th station, select the CORRECT option considering losses.
Figure for Question 39
GATEโ†’2026โ†’Propulsionโ†’Turbomachinery
Q40
MSQ[2 Marks]
The figure below shows the velocity triangles at the inlet and outlet of the rotor of a low hub-to-tip ratio axial compressor at the mid-span of the blade. The absolute and relative velocities of the flow are denoted by C and W, respectively. The subscripts 1 and 2 refer to the locations before and after the rotor, respectively. The blade velocity is denoted by U. Select the CORRECT statement(s) for this device.
Figure for Question 40
GATEโ†’2025โ†’Propulsionโ†’Turbomachinery
Q41
NAT[2 Marks]
A single-stage axial compressor, with a 50 % degree of reaction, runs at a mean blade speed of 250 m/s. The overall pressure ratio developed is 1.3. Inlet pressure and temperature are 1 bar and 300 K, respectively. Axial velocity is 200 m/s. Specific heat at constant pressure, Cp = 1005 J/kg/K and specific heat ratio, ฮณ = 1.4. The rotor blade angle at the outlet is ___ degrees (rounded off to two decimal places).
GATEโ†’2023โ†’Propulsionโ†’Turbomachinery
Q42
MCQ[1 Mark]
In a single-spool aviation turbojet engine, which of the following is the correct relationship between the total work output WT of a 2-stage axial turbine and the total work required WC by a 6-stage axial compressor, neglecting losses?
GATEโ†’2023โ†’Propulsionโ†’Turbomachinery
Q43
MCQ[1 Mark]
For a stage of a 50% reaction ideal axial flow compressor (symmetrical blading), select the correct statement from the options given.
GATEโ†’2022โ†’Propulsionโ†’Turbomachinery
Q44
MSQ[1 Mark]
A high-pressure-ratio multistage axial compressor encounters an extreme loading mismatch during starting. Which of the following technique(s) can be used to alleviate this problem?
GATEโ†’2022โ†’Propulsionโ†’Turbomachinery
Q45
NAT[1 Mark]
In a single stage turbine, the hot gases come out of stator/nozzle at a speed of 500ย m/s500\text{ m/s} and at an angle of 70โˆ˜70^{\circ} with the turbine axis. The design speed of the rotor blade is 250ย m/s250\text{ m/s} at the mean blade radius. The rotor blade angle, \ฮฒ\ฮฒ, at the leading edge is ______ degrees (round off to one decimal place).
Figure for Question 45
GATEโ†’2022โ†’Propulsionโ†’Turbomachinery
Q46
NAT[2 Marks]
A multistage axial compressor takes air at 1ย atm1\text{ atm}, 300ย K300\text{ K} and compresses to 5ย atm5\text{ atm}. Mean blade speed 245ย m/s245\text{ m/s}, work coefficient 0.550.55. If isentropic, number of stages required is ______ (round off to next higher integer).

Engine Performance

8 Questions
GATEโ†’2026โ†’Propulsionโ†’Engine Performance
Q47
MSQ[1 Mark]
For a given air-standard power, the propulsive efficiency of a turbofan engine is more than that of a turbojet engine. Which of the following is/are the reason(s) for this?
GATEโ†’2026โ†’Propulsionโ†’Engine Performance
Q48
MCQ[2 Marks]
In an ideal turbofan engine shown in the figure below, the compressor is driven by the high pressure turbine, and the fan is driven by the low pressure turbine. The stations 0, 2, 3, 4, 4.5, and 5 refer to free-stream, compressor inlet, compressor outlet, combustor exit, high pressure turbine exit, and low pressure turbine exit, respectively, and the subscript โ€˜tโ€™ refers to the total condition. Also, ๐œ๐‘Ÿ = ๐‘‡๐‘ก0 โ„๐‘‡0, ๐œ๐‘ = ๐‘‡๐‘ก3 โ„๐‘‡๐‘ก2 and ๐œ๐œ† = ๐‘‡๐‘ก4 โ„๐‘‡0 . The total temperature ratio of the high pressure turbine (๐‘‡๐‘ก4.5 โ„๐‘‡๐‘ก4 ) is given by ______.
Figure for Question 48
GATEโ†’2025โ†’Propulsionโ†’Engine Performance
Q49
NAT[2 Marks]
An ideal turbofan with a bypass ratio of 5 has core mass flow rate, mฬ‡ a,c= 100 kg/s. The core and the fan exhausts are separate and optimally expanded. The core exhaust speed is 600 m/s and the fan exhaust speed is 120 m/s. If the fuel mass flow rate is negligible in comparison to mฬ‡ a,c, the static specific thrust (๐‘‡/mฬ‡ a,c) developed by the engine is ____ Ns/kg (rounded off to the nearest integer).
GATEโ†’2025โ†’Propulsionโ†’Engine Performance
Q50
NAT[2 Marks]
An ideal ramjet with an optimally expanded exhaust is travelling at Mach 3. The ambient temperature and pressure are 260 K and 60 kPa, respectively. The inlet air mass flow rate is 50 kg/s. Exit temperature of the exhaust gases is 700 K. Fuel mass flow rate is negligible compared to air mass flow rate. Gas constant is R= 287 J/kg/K, and specific heat ratio is ฮณ = 1.4. The thrust generated by the engine is ___ kN (rounded off to one decimal place).
GATEโ†’2023โ†’Propulsionโ†’Engine Performance
Q51
MCQ[1 Mark]
An aircraft is cruising with a forward speed Va and the jet exhaust speed relative to the engine at the exit is V . If V Va = 2, what is the propulsive efficiency? j j
GATEโ†’2023โ†’Propulsionโ†’Engine Performance
Q52
MSQ[1 Mark]
From the options given, select all that are true for turbofan engines with afterburners.
GATEโ†’2022โ†’Propulsionโ†’Engine Performance
Q53
NAT[1 Mark]
In a static test, a turbofan engine with bypass ratio of 9 has core hot exhaust speed 1.5 times that of fan exhaust speed. The engine is operated at a fuel to air ratio of f=0.03f = 0.03. Both the fan and the core streams have no pressure thrust. The ratio of fan thrust to thrust from the core engine is ______ (round off to one decimal place).
GATEโ†’2022โ†’Propulsionโ†’Engine Performance
Q54
NAT[2 Marks]
An ideal ramjet operates with exhaust gases optimally expanded to ambient pressure at altitude where temperature is 220ย K220\text{ K}. Exhaust speed is 1200ย m/s1200\text{ m/s} at 1100ย K1100\text{ K}. Cruise speed of ramjet is ______ m/s.

Basics

13 Questions
GATEโ†’2026โ†’Propulsionโ†’Basics
Q62
MCQ[1 Mark]
Which one of the following makes an ideal air-standard Stirling cycle?
GATEโ†’2026โ†’Propulsionโ†’Basics
Q63
MCQ[1 Mark]
The figure below depicts two ideal gas turbine cycles, cycle 1-2-3-4-1 and cycle 1-2-3'-4'-1, on a T-s diagram. Which one the following statements is FALSE?
Figure for Question 63
GATEโ†’2026โ†’Propulsionโ†’Basics
Q64
NAT[2 Marks]
Isobutane (C4H10) is burnt completely in pure oxygen as per the reaction given below. Given that the standard heats of formation (in kcal/mole) of isobutane, carbon dioxide, and water vapour are โ€“31.489, โ€“94.052, and โ€“60.150, respectively, the heat of reaction is ________ kcal (rounded off to 2 decimal places). C4H10 + 6.5 O2 โ†’ 4 CO2 + 5 H2O
GATEโ†’2026โ†’Propulsionโ†’Basics
Q65
NAT[2 Marks]
A furnace of 250 MW rating is used to melt and raise the temperature of aluminium from 25 oC to 900 oC. Aluminium has a solid-state specific heat, latent heat, and liquid-state specific heat of 0.9 kJ/kg-K, 390 kJ/kg, and 1.108 kJ/kg-K, respectively, and the furnace has 70% efficiency. The melting point of aluminium is 660 oC. The amount of aluminium that can be processed per hour is ________ kg (rounded off to 1 decimal place).
GATEโ†’2025โ†’Propulsionโ†’Basics
Q66
MCQ[1 Mark]
๐›ฟ๐‘„ and ๐›ฟ๐‘Š are the heat and work interactions of a system with its surroundings, and ๐‘‘๐‘ˆ is the change in the internal energy of the system. For an adiabatic process in a closed, constant pressure combustor, which one of the following options is correct?
GATEโ†’2025โ†’Propulsionโ†’Basics
Q67
MCQ[1 Mark]
A gaseous fuel mixture comprising 3 moles of methane and 2 moles of ammonia is combusted in X moles of pure oxygen in stoichiometric amount. Assuming complete combustion, with only CO2, H2O and N2 in the product gases, the value of X is ___. 3 CH4 + 2 NH3 + X O2 โ†’ Products (CO2, H2O, N2)
GATEโ†’2025โ†’Propulsionโ†’Basics
Q68
NAT[2 Marks]
Air at temperature 300 K is compressed isentropically from a pressure of 1 bar to 10 bar in a compressor. Eighty percent of the compressed air is supplied to a combustor. In the combustor, 0.88 MJ of heat is added per kg of air. The specific heat at constant pressure is Cp = 1005 J/kg/K and the specific heat ratio is ฮณ = 1.4. The temperature of the air leaving the combustor is ___ K (rounded off to one decimal place).
GATEโ†’2024โ†’Propulsionโ†’Basics
Q69
MCQ[1 Mark]
For an ideal gas, the specific heat at constant pressure is 1147 J/kg K and the ratio of specific heats is equal to 1.33. What is the value of the gas constant for this gas in J/kg K?
GATEโ†’2024โ†’Propulsionโ†’Basics
Q70
MCQ[1 Mark]
In the figure shown below, various thermodynamics processes for an ideal gas are represented. Match each curve with the process that it best represents.
Figure for Question 70
GATEโ†’2023โ†’Propulsionโ†’Basics
Q71
MCQ[2 Marks]
A scramjet engine features an intake, isolator, combustor, and a nozzle, as shown in the schematic. Station 3 indicates the combustor entry point. Assume stagnation enthalpy to be constant between Stations 1 and 3, and air to be a calorically perfect gas with specific heat ratio ฮณ. Select the correct expression for Mach number M3 at the inlet to the combustor from the options given.
Figure for Question 71
GATEโ†’2023โ†’Propulsionโ†’Basics
Q72
NAT[2 Marks]
The operating characteristics of a pump were measured to be C P = a ๏†,2 where P power coefficient C P = 3 5 , ๏† is the flow coefficient, a is a constant, D is a ๏ฒ๏ท D length scale, ๏ท is the rotation rate, ๏ฒ is fluid density, and P is the power required. The flow coefficient is a dimensionless volume flow rate scaled with ๏ท and D . Assuming that the flow rate remains the same, if the rotation rate is increased to 1.25๏ท, the power changes to ฮฑP . The value of ฮฑis ________ . (round off to two decimal places)
GATEโ†’2023โ†’Propulsionโ†’Basics
Q73
NAT[2 Marks]
A gas turbine combustor is burning methane and air at an equivalence ratio F A ฯ†= 0.5 , where ฯ†= and [ F A]stoich is the ratio of mass flow rate of fuel ๏› F A๏stoich to the mass flow rate of air at stoichiometry. If the air flow rate is mair = 20 kg/s then the mass flow rate of methane is ______ kg/s. (round off to two decimal places)
GATEโ†’2022โ†’Propulsionโ†’Basics
Q74
MCQ[2 Marks]
Which of the following is NOT always true for a combustion process taking place in a closed system?

Axial Compressors

10 Questions
GATEโ†’2026โ†’Propulsionโ†’Axial Compressors
Q37
MSQ[1 Mark]
The figure below shows the blading of the rotors of two different axial turbomachines under their typical operating conditions, labelled as Configuration I and Configuration II. Which of the following statements is/are TRUE?
Figure for Question 37
GATEโ†’2026โ†’Propulsionโ†’Axial Compressors
Q38
MSQ[1 Mark]
A multi-stage axial compressor can be operated at two points, A and B, both of which lie on the same speed line, as shown in the figure below. If ๐œ‚ is the isentropic efficiency of the compressor, select the statements that is/are TRUE.
Figure for Question 38
GATEโ†’2026โ†’Propulsionโ†’Axial Compressors
Q39
MCQ[2 Marks]
The figure below shows a compressor stage with station numbers 1, 2, and 3 as indicated. If ๐‘0๐‘– , ๐‘‡0๐‘– , and ๐ถ๐‘– refer to the average values of total pressure, total temperature, and absolute flow speed, respectively, at the ๐‘– th station, select the CORRECT option considering losses.
Figure for Question 39
GATEโ†’2026โ†’Propulsionโ†’Axial Compressors
Q40
MSQ[2 Marks]
The figure below shows the velocity triangles at the inlet and outlet of the rotor of a low hub-to-tip ratio axial compressor at the mid-span of the blade. The absolute and relative velocities of the flow are denoted by C and W, respectively. The subscripts 1 and 2 refer to the locations before and after the rotor, respectively. The blade velocity is denoted by U. Select the CORRECT statement(s) for this device.
Figure for Question 40
GATEโ†’2025โ†’Propulsionโ†’Axial Compressors
Q41
NAT[2 Marks]
A single-stage axial compressor, with a 50 % degree of reaction, runs at a mean blade speed of 250 m/s. The overall pressure ratio developed is 1.3. Inlet pressure and temperature are 1 bar and 300 K, respectively. Axial velocity is 200 m/s. Specific heat at constant pressure, Cp = 1005 J/kg/K and specific heat ratio, ฮณ = 1.4. The rotor blade angle at the outlet is ___ degrees (rounded off to two decimal places).
GATEโ†’2023โ†’Propulsionโ†’Axial Compressors
Q42
MCQ[1 Mark]
In a single-spool aviation turbojet engine, which of the following is the correct relationship between the total work output WT of a 2-stage axial turbine and the total work required WC by a 6-stage axial compressor, neglecting losses?
GATEโ†’2023โ†’Propulsionโ†’Axial Compressors
Q43
MCQ[1 Mark]
For a stage of a 50% reaction ideal axial flow compressor (symmetrical blading), select the correct statement from the options given.
GATEโ†’2022โ†’Propulsionโ†’Axial Compressors
Q44
MSQ[1 Mark]
A high-pressure-ratio multistage axial compressor encounters an extreme loading mismatch during starting. Which of the following technique(s) can be used to alleviate this problem?
GATEโ†’2022โ†’Propulsionโ†’Axial Compressors
Q45
NAT[1 Mark]
In a single stage turbine, the hot gases come out of stator/nozzle at a speed of 500ย m/s500\text{ m/s} and at an angle of 70โˆ˜70^{\circ} with the turbine axis. The design speed of the rotor blade is 250ย m/s250\text{ m/s} at the mean blade radius. The rotor blade angle, \ฮฒ\ฮฒ, at the leading edge is ______ degrees (round off to one decimal place).
Figure for Question 45
GATEโ†’2022โ†’Propulsionโ†’Axial Compressors
Q46
NAT[2 Marks]
A multistage axial compressor takes air at 1ย atm1\text{ atm}, 300ย K300\text{ K} and compresses to 5ย atm5\text{ atm}. Mean blade speed 245ย m/s245\text{ m/s}, work coefficient 0.550.55. If isentropic, number of stages required is ______ (round off to next higher integer).

Aircraft Engine Performance

8 Questions
GATEโ†’2026โ†’Propulsionโ†’Aircraft Engine Performance
Q47
MSQ[1 Mark]
For a given air-standard power, the propulsive efficiency of a turbofan engine is more than that of a turbojet engine. Which of the following is/are the reason(s) for this?
GATEโ†’2026โ†’Propulsionโ†’Aircraft Engine Performance
Q48
MCQ[2 Marks]
In an ideal turbofan engine shown in the figure below, the compressor is driven by the high pressure turbine, and the fan is driven by the low pressure turbine. The stations 0, 2, 3, 4, 4.5, and 5 refer to free-stream, compressor inlet, compressor outlet, combustor exit, high pressure turbine exit, and low pressure turbine exit, respectively, and the subscript โ€˜tโ€™ refers to the total condition. Also, ๐œ๐‘Ÿ = ๐‘‡๐‘ก0 โ„๐‘‡0, ๐œ๐‘ = ๐‘‡๐‘ก3 โ„๐‘‡๐‘ก2 and ๐œ๐œ† = ๐‘‡๐‘ก4 โ„๐‘‡0 . The total temperature ratio of the high pressure turbine (๐‘‡๐‘ก4.5 โ„๐‘‡๐‘ก4 ) is given by ______.
Figure for Question 48
GATEโ†’2025โ†’Propulsionโ†’Aircraft Engine Performance
Q49
NAT[2 Marks]
An ideal turbofan with a bypass ratio of 5 has core mass flow rate, mฬ‡ a,c= 100 kg/s. The core and the fan exhausts are separate and optimally expanded. The core exhaust speed is 600 m/s and the fan exhaust speed is 120 m/s. If the fuel mass flow rate is negligible in comparison to mฬ‡ a,c, the static specific thrust (๐‘‡/mฬ‡ a,c) developed by the engine is ____ Ns/kg (rounded off to the nearest integer).
GATEโ†’2025โ†’Propulsionโ†’Aircraft Engine Performance
Q50
NAT[2 Marks]
An ideal ramjet with an optimally expanded exhaust is travelling at Mach 3. The ambient temperature and pressure are 260 K and 60 kPa, respectively. The inlet air mass flow rate is 50 kg/s. Exit temperature of the exhaust gases is 700 K. Fuel mass flow rate is negligible compared to air mass flow rate. Gas constant is R= 287 J/kg/K, and specific heat ratio is ฮณ = 1.4. The thrust generated by the engine is ___ kN (rounded off to one decimal place).
GATEโ†’2023โ†’Propulsionโ†’Aircraft Engine Performance
Q51
MCQ[1 Mark]
An aircraft is cruising with a forward speed Va and the jet exhaust speed relative to the engine at the exit is V . If V Va = 2, what is the propulsive efficiency? j j
GATEโ†’2023โ†’Propulsionโ†’Aircraft Engine Performance
Q52
MSQ[1 Mark]
From the options given, select all that are true for turbofan engines with afterburners.
GATEโ†’2022โ†’Propulsionโ†’Aircraft Engine Performance
Q53
NAT[1 Mark]
In a static test, a turbofan engine with bypass ratio of 9 has core hot exhaust speed 1.5 times that of fan exhaust speed. The engine is operated at a fuel to air ratio of f=0.03f = 0.03. Both the fan and the core streams have no pressure thrust. The ratio of fan thrust to thrust from the core engine is ______ (round off to one decimal place).
GATEโ†’2022โ†’Propulsionโ†’Aircraft Engine Performance
Q54
NAT[2 Marks]
An ideal ramjet operates with exhaust gases optimally expanded to ambient pressure at altitude where temperature is 220ย K220\text{ K}. Exhaust speed is 1200ย m/s1200\text{ m/s} at 1100ย K1100\text{ K}. Cruise speed of ramjet is ______ m/s.

Rocket Propulsion

7 Questions
GATEโ†’2026โ†’Propulsionโ†’Rocket Propulsion
Q55
MCQ[2 Marks]
An ideal rocket has characteristic exhaust velocity of 1200 m/s, mass flow rate of 75 kg/s, thrust coefficient of 1.5, and nozzle throat area of 0.025 m2. The chamber pressure in kPa and the specific impulse due to gravity in seconds are ________, respectively. Assume that the acceleration due to gravity is 9.8 m/s2.
GATEโ†’2026โ†’Propulsionโ†’Rocket Propulsion
Q56
MCQ[2 Marks]
Consider a launch vehicle of mass 10 tons being launched vertically. The vehicle has 8 tons of propellant, which burns completely at a constant rate over 50 s. If the engine specific impulse is 250 s, and the acceleration due to gravity at sea level is ๐‘”0 , the acceleration experienced by the vehicle at lift-off is ________.
GATEโ†’2025โ†’Propulsionโ†’Rocket Propulsion
Q57
MCQ[1 Mark]
An ideal two-stage rocket has identical specific impulse and structural coefficient for its two stages. For an optimized rocket, the two stages have identical payload ratio as well. The payload is 2 tons and the initial mass of the rocket is 200 tons. The mass of the second stage of the rocket (including the final payload mass) is ____ tons.
GATEโ†’2025โ†’Propulsionโ†’Rocket Propulsion
Q58
NAT[2 Marks]
A monopropellant liquid rocket engine has 800 injectors of diameter 4 mm each, and with a discharge coefficient of 0.65. The liquid propellant of density 1000 kg/m3 flows through the injectors. There is a pressure difference of 10 bar across the injectors. The specific impulse of the rocket is 1500 m/s. The thrust generated by the rocket is _____ kN (rounded off to one decimal place).
GATEโ†’2023โ†’Propulsionโ†’Rocket Propulsion
Q59
NAT[1 Mark]
A supersonic vehicle powered by a ramjet engine is cruising at a speed of 1000 m/s. The ramjet engine burns hydrogen in a subsonic combustor to produce thrust. The heat of combustion for hydrogen is 120 MJ/kg. The overall efficiency of the engine ๏จ,o defined as the ratio of propulsive power to the total heat release in the combustor, is 40%. Taking acceleration due to gravity g = 10 m/s2, the 0 specific impulse of the engine is _____________ seconds. (round off to the nearest integer). Aerospace Engineering (AE) Q.36 โ€“ Q.65 Carry TWO marks Each
GATEโ†’2023โ†’Propulsionโ†’Rocket Propulsion
Q60
MCQ[2 Marks]
Two missiles A and B powered by solid rocket motors have identical specific impulse, liftoff mass of 5600 kg each, and burn durations of At = 30 s and Bt = 70 s, respectively. The propellant mass flow rates, m A and mB , for missiles A and B, respectively, are given by m A = 120 kg/s, 0 ๏‚ฃ๏‚ฃt 30 mB = 70 kg/s, 0 ๏‚ฃ๏‚ฃt 70 Neglecting gravity and aerodynamic forces, the relationship between the final velocities V and V of missiles A and B, respectively, is given by A B
GATEโ†’2023โ†’Propulsionโ†’Rocket Propulsion
Q61
NAT[2 Marks]
Consider a cryogenic liquid rocket engine using an expander cycle with liquid hydrogen and liquid oxygen as the two propellants. The mass flow rate of 32 kg/s, and the mass flow rate of hydrogen mH 2 into the combustion chamber is oxygen mO2 into the chamber is such that mO2 mH 2 = 8 . The combustion of hydrogen and oxygen is at stoichiometry. Assuming that the rate of the forward reaction is much larger than that of the reverse reaction, the rate of formation of H2O is ________ kmol/s. (round off to the nearest integer) END OF QUESTION PAPER

Propulsion Fundamentals and Aerothermodynamics

13 Questions
GATEโ†’2026โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q62
MCQ[1 Mark]
Which one of the following makes an ideal air-standard Stirling cycle?
GATEโ†’2026โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q63
MCQ[1 Mark]
The figure below depicts two ideal gas turbine cycles, cycle 1-2-3-4-1 and cycle 1-2-3'-4'-1, on a T-s diagram. Which one the following statements is FALSE?
Figure for Question 63
GATEโ†’2026โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q64
NAT[2 Marks]
Isobutane (C4H10) is burnt completely in pure oxygen as per the reaction given below. Given that the standard heats of formation (in kcal/mole) of isobutane, carbon dioxide, and water vapour are โ€“31.489, โ€“94.052, and โ€“60.150, respectively, the heat of reaction is ________ kcal (rounded off to 2 decimal places). C4H10 + 6.5 O2 โ†’ 4 CO2 + 5 H2O
GATEโ†’2026โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q65
NAT[2 Marks]
A furnace of 250 MW rating is used to melt and raise the temperature of aluminium from 25 oC to 900 oC. Aluminium has a solid-state specific heat, latent heat, and liquid-state specific heat of 0.9 kJ/kg-K, 390 kJ/kg, and 1.108 kJ/kg-K, respectively, and the furnace has 70% efficiency. The melting point of aluminium is 660 oC. The amount of aluminium that can be processed per hour is ________ kg (rounded off to 1 decimal place).
GATEโ†’2025โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q66
MCQ[1 Mark]
๐›ฟ๐‘„ and ๐›ฟ๐‘Š are the heat and work interactions of a system with its surroundings, and ๐‘‘๐‘ˆ is the change in the internal energy of the system. For an adiabatic process in a closed, constant pressure combustor, which one of the following options is correct?
GATEโ†’2025โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q67
MCQ[1 Mark]
A gaseous fuel mixture comprising 3 moles of methane and 2 moles of ammonia is combusted in X moles of pure oxygen in stoichiometric amount. Assuming complete combustion, with only CO2, H2O and N2 in the product gases, the value of X is ___. 3 CH4 + 2 NH3 + X O2 โ†’ Products (CO2, H2O, N2)
GATEโ†’2025โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q68
NAT[2 Marks]
Air at temperature 300 K is compressed isentropically from a pressure of 1 bar to 10 bar in a compressor. Eighty percent of the compressed air is supplied to a combustor. In the combustor, 0.88 MJ of heat is added per kg of air. The specific heat at constant pressure is Cp = 1005 J/kg/K and the specific heat ratio is ฮณ = 1.4. The temperature of the air leaving the combustor is ___ K (rounded off to one decimal place).
GATEโ†’2024โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q69
MCQ[1 Mark]
For an ideal gas, the specific heat at constant pressure is 1147 J/kg K and the ratio of specific heats is equal to 1.33. What is the value of the gas constant for this gas in J/kg K?
GATEโ†’2024โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q70
MCQ[1 Mark]
In the figure shown below, various thermodynamics processes for an ideal gas are represented. Match each curve with the process that it best represents.
Figure for Question 70
GATEโ†’2023โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q71
MCQ[2 Marks]
A scramjet engine features an intake, isolator, combustor, and a nozzle, as shown in the schematic. Station 3 indicates the combustor entry point. Assume stagnation enthalpy to be constant between Stations 1 and 3, and air to be a calorically perfect gas with specific heat ratio ฮณ. Select the correct expression for Mach number M3 at the inlet to the combustor from the options given.
Figure for Question 71
GATEโ†’2023โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q72
NAT[2 Marks]
The operating characteristics of a pump were measured to be C P = a ๏†,2 where P power coefficient C P = 3 5 , ๏† is the flow coefficient, a is a constant, D is a ๏ฒ๏ท D length scale, ๏ท is the rotation rate, ๏ฒ is fluid density, and P is the power required. The flow coefficient is a dimensionless volume flow rate scaled with ๏ท and D . Assuming that the flow rate remains the same, if the rotation rate is increased to 1.25๏ท, the power changes to ฮฑP . The value of ฮฑis ________ . (round off to two decimal places)
GATEโ†’2023โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q73
NAT[2 Marks]
A gas turbine combustor is burning methane and air at an equivalence ratio F A ฯ†= 0.5 , where ฯ†= and [ F A]stoich is the ratio of mass flow rate of fuel ๏› F A๏stoich to the mass flow rate of air at stoichiometry. If the air flow rate is mair = 20 kg/s then the mass flow rate of methane is ______ kg/s. (round off to two decimal places)
GATEโ†’2022โ†’Propulsionโ†’Propulsion Fundamentals and Aerothermodynamics
Q74
MCQ[2 Marks]
Which of the following is NOT always true for a combustion process taking place in a closed system?

Centrifugal Compressors

5 Questions
GATEโ†’2026โ†’Propulsionโ†’Centrifugal Compressors
Q75
NAT[2 Marks]
A centrifugal compressor has a constant-width radial diffuser. The diameters at the diffuser inlet and outlet are 0.2 m and 0.3 m, respectively. The flow at the diffuser inlet and outlet is assumed to be steady and uniform. The average velocity at the diffuser inlet and outlet are (60 ๐žฬ‚๐ซ + 75 ๐žฬ‚๐›‰ ) m/s and (๐‘ข ๐žฬ‚๐ซ + 50 ๐žฬ‚๐›‰ ) m/s, respectively. If the flow through the diffuser is treated as steady and incompressible, the value of ๐‘ข is ________ (rounded off to the nearest integer).
GATEโ†’2025โ†’Propulsionโ†’Centrifugal Compressors
Q76
NAT[1 Mark]
In a centrifugal compressor, the eye tip diameter is 10 cm. For a shaft rotational speed of 490 rotations per second, the tangential speed at the inducer tip is ___ m/s (rounded off to one decimal place).
GATEโ†’2023โ†’Propulsionโ†’Centrifugal Compressors
Q77
NAT[2 Marks]
A centrifugal air compressor has inlet root diameter of 0.25 m and the outlet diameter of the impeller is 0.6 m. The pressure ratio is 5.0. The air at the inlet of the rotor is at 1 atm and 25oC. The polytropic efficiency is 0.8 and slip factor is 0.92. Use C p = 1.004 kJ/kg-K and ๏ง= 1.4 . The impeller speed in revolutions per minute (RPM) is _________. (round off to the nearest integer)
GATEโ†’2022โ†’Propulsionโ†’Centrifugal Compressors
Q78
MCQ[1 Mark]
The region of highest static temperature in a rocket engine and the region of highest heat flux are respectively.
GATEโ†’2022โ†’Propulsionโ†’Centrifugal Compressors
Q79
MSQ[2 Marks]
A rocket operates at absolute chamber pressure of 20 bar to produce thrust F1F_1, optimally expanded with CF,1=1.42C_{F,1} = 1.42. Same rocket at 50 bar produces F2F_2 and CF,2C_{F,2}. Which statement(s) is/are correct?

Non-Rotating Propulsion Components

1 Question
GATEโ†’2026โ†’Propulsionโ†’Non-Rotating Propulsion Components
Q80
MSQ[2 Marks]
Which of the following process(es) is/are involved in the compression of air in an ideal ramjet engine?

Axial Turbines

1 Question
GATEโ†’2026โ†’Propulsionโ†’Axial Turbines
Q81
NAT[2 Marks]
A gas mixture at a pressure of 800 kPa and a density of 5 kg/m3 enters a turbine stage. The temperature of the gas at the nozzle exit and the stage exit are 790 K and 750 K, respectively. Assume the specific heats are constant for the gas mixture in the range of temperatures considered. The specific heat at constant pressure is 0.72 kJ/kg-K and the ratio of specific heats is 1.33. The value of the degree of reaction of the turbine stage is ________ (rounded off to 2 decimal places).