Back to Sections

Type:ALLMCQNATMSQ

Compressible Flows(17)Potential Flow Theory(11)Basic Fluid Mechanics(10)Airfoils and Wings(49)Potential Flow and Viscous Flows(11)Wind Tunnel Testing(1)

Compressible Flows

17 Questions

GATE→2026→Aerodynamics→Compressible Flows

Q1

MCQ[1 Mark]

In the figure shown below, the flow at the nozzle exit is ________.

(A)

overexpanded

(B)

underexpanded

(C)

ideally expanded

(D)

subsonic

Explanation

GATE→2026→Aerodynamics→Compressible Flows

Q2

MSQ[1 Mark]

A flow is steady, inviscid and one-dimensional, with no shaft work or body forces. Which of the following is/are possible under the given conditions?

(A)

Oblique shocks

(B)

Sound propagation

(C)

Rayleigh flow

(D)

Fanno flow

Explanation

GATE→2026→Aerodynamics→Compressible Flows

Q3

NAT[2 Marks]

Consider a centered Prandtl-Meyer expansion fan at a 𝜃 = 4° corner in a Mach 1.78 air flow, as shown in the figure below. The angle ψ (see figure) made by the ending wave of the fan with respect to the incoming stream is ________ degrees (rounded off to 1 decimal place). An excerpt from the table of Prandtl-Meyer function for air is provided below. M ν [deg] M ν [deg] M ν [deg] 1.72 18.40 1.82 21.30 1.92 24.15 1.74 18.98 1.84 21.88 1.94 24.71 1.76 19.56 1.86 22.45 1.96 25.27 1.78 20.15 1.88 23.02 1.98 25.83 1.80 20.73 1.90 23.59 2.00 26.38

Explanation

GATE→2026→Aerodynamics→Compressible Flows

Q4

NAT[2 Marks]

A Mach 1.5 air flow enters a round duct of length 20 cm and diameter 3 cm. If the flow exits with Mach number 1.1, the average Fanning friction factor 𝑓 of the duct is ________ × 10−3 (rounded off to 1 decimal place). An excerpt from the Fanno flow table for air is given below. M 1.1 1.2 1.3 1.4 1.5 1.6 𝟒𝒇𝑳∗ × 𝟏𝟎𝟒 99.35 336.4 648.3 997.4 1361 1724 𝑫

Explanation

GATE→2025→Aerodynamics→Compressible Flows

Q5

NAT[2 Marks]

An aircraft is flying at an altitude of 4500 m above sea level, where the ambient pressure, temperature and density are 57 kPa, 259 K and 0.777 kg/m3, respectively. The speed of the aircraft (𝑉) is 230 m/s. Gas constant R= 287 J/kg/K, and specific heat ratio 𝛾 = 1.4. If the stagnation pressure is 𝑝𝑜, and static pressure is 𝑝, the value of [ 𝑝𝑜−𝑝 1 2𝜌𝑉2] is ________ (rounded off to two decimal places).

Explanation

GATE→2025→Aerodynamics→Compressible Flows

Q6

NAT[2 Marks]

A supersonic stream of an ideal gas at Mach number 𝑀1 = 5 is turned by a ramp, as shown in the figure. The ramp angle is 20o. The pressure ratio is 𝑝2 𝑝1 = 7.125 and the specific heat ratio is γ = 1.4. The pressure coefficient on the ramp surface is _______ (rounded off to two decimal places).

Explanation

GATE→2025→Aerodynamics→Compressible Flows

Q7

NAT[2 Marks]

A perfect gas flows through a frictionless constant-area duct with heat addition. The inlet conditions are as follows: pressure 100 kPa, density 1 kg/m3, and velocity 100 m/s. At a particular downstream location, the gas velocity is 200 m/s. The static pressure at the downstream location is ______ kPa (answer in integer).

Explanation

GATE→2025→Aerodynamics→Compressible Flows

Q8

NAT[2 Marks]

The mass flow rate in a supersonic wind tunnel is 2 kg/s when the stagnation pressure and stagnation temperature are 1 MPa and 800 K, respectively. If the stagnation pressure and stagnation temperature are changed to 3 MPa and 200 K, the mass flow rate in the tunnel changes to _______ kg/s (answer in integer).

Explanation

GATE→2023→Aerodynamics→Compressible Flows

Q9

MCQ[2 Marks]

A supersonic aircraft has an air intake ramp that can be rotated about the leading edge O such that the shock from the leading edge meets the cowl lip as shown in the figure. Select all the correct statement(s) as per oblique shock theory when the flight Mach number M is increased.

(A)

It is always possible to find a ramp setting θRAMP such that the shock still meets the cowl lip ( βSHOCK remains the same).

(B)

If θRAMP is held fixed, the shock angle βSHOCK will increase.

(C)

If M exceeds a critical value, it would NOT be possible to find a ramp setting θRAMP such that the shock still meets the cowl lip ( βSHOCK remains the same).

(D)

−1 1  Shock angle βSHOCK  sin    M  Aerospace Engineering (AE)

Explanation

GATE→2023→Aerodynamics→Compressible Flows

Q10

MCQ[2 Marks]

A perfect gas stored in a large reservoir exhausts into the atmosphere through a convergent duct. The reservoir pressure is P0 and temperature is T0. The jet emerges from the nozzle at choked conditions with average velocity u, Mach number M, pressure p, temperature T, and density . If the reservoir pressure is increased, then

(A)

u, M, p, T, and  increase

(B)

u, p, T, and  increase, but M remains the same

(C)

u, M, and T remain the same, but p and  increase

(D)

u, M, T and  remain the same, but p increases

Explanation

GATE→2023→Aerodynamics→Compressible Flows

Q11

MSQ[2 Marks]

Consider a one-dimensional inviscid supersonic flow in a diverging duct with heat addition (Qin) as shown. Which of the following statement(s) is/are always TRUE?

(A)

Mach number, M 2  M 1

(B)

Stagnation pressure, P1o  P2o

(C)

Static pressure, P2  P1

(D)

Stagnation temperature, T1o  T2o Aerospace Engineering (AE)

Explanation

GATE→2023→Aerodynamics→Compressible Flows

Q12

MSQ[2 Marks]

For an airfoil, which of the relations given about the critical Mach number M cr and drag divergence Mach number M dd is/are correct?

(A)

M cr  M dd

(B)

M cr  1.0

(C)

M  1.0 dd

(D)

M cr  1.0 Aerospace Engineering (AE)

Explanation

GATE→2022→Aerodynamics→Compressible Flows

Q13

MCQ[1 Mark]

The point of maximum entropy on a Fanno-curve in a Temperature-Entropy (T-s) diagram represents the

(A)

maximum flow Mach number

(B)

minimum flow Mach number

(C)

sonic Mach number

(D)

normal shock in the flow

Explanation

GATE→2022→Aerodynamics→Compressible Flows

Q14

MSQ[1 Mark]

Across an oblique shock wave in a calorifically perfect gas,

(A)

the stagnation enthalpy changes

(B)

the stagnation entropy changes

(C)

the stagnation temperature changes

(D)

the speed of sound changes

Explanation

GATE→2022→Aerodynamics→Compressible Flows

Q15

MSQ[2 Marks]

A convergent nozzle fed from a constant pressure, constant temperature reservoir is discharging air to atmosphere at 1 bar with choked flow at the exit (Q). If exit area is increased while all reservoir and ambient conditions remain the same, then at steady state

(A)

the nozzle will remain choked

(B)

the nozzle will be un-choked

(C)

the Mach number at section P will increase

(D)

the Mach number at section P will decrease

Explanation

GATE→2022→Aerodynamics→Compressible Flows

Q16

NAT[2 Marks]

In a converging duct, area and velocity at section P are $1\text{ m}^2$ and $15\text{ m/s}$. Temperature $300\text{ K}$, isothermal flow. Minimum area required at section Q for $M \le 0.3$ is ______ $m^2$ (round off to two decimal places).

Explanation

GATE→2022→Aerodynamics→Compressible Flows

Q17

NAT[2 Marks]

A convergent-divergent nozzle designed for exit Mach number 2.3 discharges air to atmosphere ($1\text{ bar}$). Reservoir pressure $25\text{ bar}$. Minimum percentage change in reservoir pressure required to eliminate expansion waves at exit is ______ %.

Explanation

Potential Flow Theory

11 Questions

GATE→2026→Aerodynamics→Potential Flow Theory

Q88

MCQ[1 Mark]

In fluid dynamics, d’Alembert’s paradox refers to which one of the following?

(A)

Deviation of drag from 𝐷 ∝ 𝑣 2 at very low speeds

(B)

Deviation of drag from 𝐷 ∝ 𝑣 2 at high subsonic speeds

(C)

Prediction of zero drag by potential flow theory

(D)

Presence of shocks in transonic flows

Explanation

GATE→2026→Aerodynamics→Potential Flow Theory

Q89

MCQ[1 Mark]

The velocity potential function (𝜑) given below represents which one of the following? 𝜑 = 5𝑥 − 12𝑦

(A)

Doublet

(B)

Irrotational vortex

(C)

Source

(D)

Uniform flow

Explanation

GATE→2026→Aerodynamics→Potential Flow Theory

Q90

MSQ[2 Marks]

Consider the flow over an oval modeled using the elementary potential flows as shown below. 𝑈 represents uniform flow velocity and 𝛤 represents circulation around an irrotational line vortex. Which of the following statements is/are TRUE for this model?

(A)

Increasing 𝑈 enlarges the oval

(B)

Increasing 𝛤 enlarges the oval

(C)

Interchanging the sense of the two vortices does not alter the oval

(D)

Moving the vortices too far apart causes the oval to break up

Explanation

GATE→2025→Aerodynamics→Potential Flow Theory

Q91

MCQ[1 Mark]

For a two-dimensional incompressible flow over a flat plate, the laminar boundary layer thickness at a distance 𝑥 from the leading edge is 𝛿. If 𝑅𝑒𝑥 is the Reynolds number defined based on length scale x, ( 𝛿 𝑥) is proportional to ______.

(A)

𝑅𝑒𝑥 −1/2

(B)

𝑅𝑒𝑥 −1

(C)

𝑅𝑒𝑥 −3/2

(D)

𝑅𝑒𝑥 −2

Explanation

GATE→2025→Aerodynamics→Potential Flow Theory

Q92

MCQ[1 Mark]

Consider a pair of point vortices with clockwise circulation Γ each. The distance between their centers is 𝑎, as shown in the figure. Assume two-dimensional, incompressible, inviscid flow. Which one of the following options is correct?

(A)

The vortices translate downwards together with a velocity Γ 2𝜋𝑎 .

(B)

The vortices translate upwards together with a velocity Γ 2𝜋𝑎 .

(C)

The vortices rotate clockwise around each other about their centroid O.

(D)

The vortices rotate counter-clockwise around each other about their centroid O.

Explanation

GATE→2025→Aerodynamics→Potential Flow Theory

Q93

NAT[1 Mark]

The lift per unit span for a spinning circular cylinder in a potential flow is 6 N/m. The free-stream velocity is 30 m/s, and the density of air is 1.225 kg/m3. The circulation around the cylinder is ____ m2/s (rounded off to two decimal places).

Explanation

GATE→2023→Aerodynamics→Potential Flow Theory

Q94

MCQ[1 Mark]

A two-dimensional potential flow solution for flow past an airfoil has a streamline pattern as shown in the figure. Which of the following conditions is additionally required to satisfy the Kutta condition?

(A)

Addition of a source of strength Q  0

(B)

Addition of a source of strength Q  0

(C)

Addition of a circulation of strength  0 (counter-clockwise)

(D)

Addition of a circulation of strength  0 (clockwise) Aerospace Engineering (AE)

Explanation

GATE→2023→Aerodynamics→Potential Flow Theory

Q95

MCQ[1 Mark]

Consider the Blasius solution for the incompressible laminar flat plate boundary layer. Among the following options, select the correct relation for the development of the momentum thickness θ with distance x from the leading edge along the length of the plate.

(A)

θ x 2 3

(B)

θ x1 2

(C)

θ x1 7

(D)

θ x −2 3

Explanation

GATE→2023→Aerodynamics→Potential Flow Theory

Q96

MCQ[1 Mark]

In a two-dimensional potential flow, the doublet is a limit of the superposition of

(A)

a uniform stream and a source

(B)

a source and a sink of equal strength

(C)

a uniform stream and a sink

(D)

a source and a vortex Aerospace Engineering (AE)

Explanation

GATE→2023→Aerodynamics→Potential Flow Theory

Q97

NAT[2 Marks]

In a potential flow, a uniform stream of strength U directed along the x-axis and  − − four line sources (2-dimensional) of strengths , , , are placed along 2 3 4 5 the x-axis at x = 0, 1, 2 and 3, respectively. The strength of an additional line source to be placed at x = 4 such that a closed streamline encircles all five sources is _____. (round off to two decimal places).

Explanation

GATE→2022→Aerodynamics→Potential Flow Theory

Q98

MCQ[1 Mark]

Consider a two-dimensional potential flow over a cylinder. If the freestream speed is $U_{\infty}$, the maximum speed on the cylinder surface is

(A)

U_inf / 2

(B)

3 U_inf / 2

(C)

2 U_inf

(D)

4 U_inf / 3

Explanation

Basic Fluid Mechanics

10 Questions

GATE→2026→Aerodynamics→Basic Fluid Mechanics

Q29

MCQ[2 Marks]

An experimental study is planned to map out the low-Reynolds number incompressible steady two-dimensional aerodynamic characteristics of a promising novel airfoil. The operational parameters of the problem are the speed, density and viscosity of the freestream, the chord of the airfoil and its angle of attack. If the objective is to achieve this with the minimum number of test runs 𝑁𝑚𝑖𝑛 while taking 10 equally-spaced test values of each independent parameter of the problem in a suitable range, then 𝑁𝑚𝑖𝑛 is ________.

(A)

10

(B)

100

(C)

10,000

(D)

1,00,000

Explanation

GATE→2025→Aerodynamics→Basic Fluid Mechanics

Q30

MCQ[1 Mark]

In a fluid flow, Mach number is an estimate of _____.

(A)

√inertia force viscous force

(B)

√inertia force elastic force

(C)

√elastic force viscous force

(D)

√viscous force inertia force

Explanation

GATE→2025→Aerodynamics→Basic Fluid Mechanics

Q31

NAT[2 Marks]

In a low-speed airplane, a venturimeter with 1.3:1 area ratio is used for airspeed measurement. The airplane’s maximum speed at sea level is 90 m/s. If the density of air at sea level is 1.225 kg/m3, the maximum pressure difference between the inlet and the throat of the venturimeter is ________ kPa (rounded off to two decimal places).

Explanation

GATE→2023→Aerodynamics→Basic Fluid Mechanics

Q32

NAT[1 Mark]

The ratio of the speed of sound in H2 (molecular weight 2 kg/kmol) to that in N2 (molecular weight 28 kg/kmol) at temperature 300 K and pressure 2 bar is ____. (round off to two decimal places)

Explanation

GATE→2023→Aerodynamics→Basic Fluid Mechanics

Q33

NAT[2 Marks]

Enstrophy is defined as the square of the magnitude of vorticity. For the three-dimensional velocity field V = (4 x − 1.5 y + 2.5 z )iˆ + (1.5 x − 1.5 y ) ˆj + ( 0.7 xy ) kˆ , the enstrophy at location (1, 1, 1) is ________ . (round off to two decimal places) Aerospace Engineering (AE)

Explanation

GATE→2022→Aerodynamics→Basic Fluid Mechanics

Q34

MCQ[1 Mark]

Consider steady, two-dimensional, incompressible flow over a non-porous flat plate. For control volume PQRS, speed at PQ is $u_{\infty}$ and at RS is $u(y) = A_0(y/h)^n$. The value of $A_0$ for which the flow through PS will vanish is:

(A)

u_inf / (n+1)

(B)

u_inf (n+1)

(C)

u_inf / (n-1)

(D)

u_inf (n-1)

Explanation

GATE→2022→Aerodynamics→Basic Fluid Mechanics

Q35

MCQ[1 Mark]

Consider the velocity distribution $u(y)$ in adjacent fluid layers L1 and L2. For the given profile, the viscous force exerted by L1 on L2 is

(A)

to the right

(B)

to the left

(C)

vertically upwards

(D)

vertically downwards

Explanation

GATE→2022→Aerodynamics→Basic Fluid Mechanics

Q36

MCQ[2 Marks]

A cylindrical object of diameter 900 mm is designed to move axially in air at $60\text{ m/s}$. Its drag is estimated on a geometrically half-scaled model in water, assuming flow similarity. Viscosities and densities given. Drag measured for model is 2280 N. Drag experienced by full-scale object is ______ N.

(A)

322

(B)

644

(C)

1288

(D)

2576

Explanation

GATE→2022→Aerodynamics→Basic Fluid Mechanics

Q37

NAT[2 Marks]

A rotational velocity field in an air flow is given as $\vec{V} = ay\hat{i} + bx\hat{j}$, with $a = 10\text{ s}^{-1}$, $b = 20\text{ s}^{-1}$. Air density is $1.0\text{ kg/m}^3$ and pressure at $(0,0)$ is $100\text{ kPa}$. Pressure at $(6,8)$ is ______ kPa (rounded off to nearest integer).

Explanation

GATE→2022→Aerodynamics→Basic Fluid Mechanics

Q38

NAT[2 Marks]

Consider a solid cylinder housed inside another cylinder. Radius of inner cylinder is $1\text{ m}$ and height $2\text{ m}$. Gap is $5\text{ mm}$, viscosity $10^{-4}\text{ Pa-s}$, angular speed $5\text{ rad/s}$. Driving moment is ______ Nm (round off to two decimal places).

Explanation

Airfoils and Wings

49 Questions

GATE→2026→Aerodynamics→Airfoils and Wings

Q39

MCQ[1 Mark]

The fundamental purpose of the Kutta condition in the thin airfoil theory is ________.

(A)

to determine the total strength of the source distribution

(B)

to determine the speed of the uniform flow

(C)

to incorporate the essential effect of viscosity in the potential flow theory

(D)

to incorporate the concept of induced drag in the inviscid theory

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q40

MSQ[1 Mark]

Shown below are qualitative illustrations of the lift curve for an airfoil when two different control surfaces are in their respective retracted and deployed configurations. Which of the following is/are TRUE?

(A)

Figure P is for a flap

(B)

Figure P is for a slat

(C)

Figure Q is for a slat

(D)

Figure Q is for a flap

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q41

MSQ[1 Mark]

Which of the following statements is/are TRUE regarding critical and drag divergence Mach numbers of a wing?

(A)

Critical Mach number is the minimum freestream Mach number for which sonic condition is attained somewhere over the wing

(B)

Drag divergence Mach number is always higher than the critical Mach number

(C)

Drag divergence Mach number is the local Mach number over the wing at which the drag increases drastically

(D)

Critical Mach number is independent of the angle of attack

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q42

NAT[1 Mark]

An elliptic wing has a span of 6 m and a planform area of 6 m2. When generating a lift coefficient of 0.6, the induced drag it incurs is ________ × 10−3 (rounded off to 1 decimal place).

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q43

MSQ[2 Marks]

What is/are the use(s) of the single horseshoe vortex model of finite wing aerodynamic theory?

(A)

It can approximate the wing pitching moment coefficient

(B)

It can approximate the wing induced drag coefficient

(C)

It can approximate the effect of the wing on the induced drag coefficient of a typical horizontal tail

(D)

It can approximate the aerodynamic benefit/penalty of formation flight compared to isolated flight

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q44

NAT[2 Marks]

For an airfoil section the pitching moment coefficient is determined about a reference point that is 0.3 times the chord behind the leading edge. It varies with the lift coefficient as shown in the table below. The distance of the aerodynamic center from the leading edge of the airfoil as a fraction of the chord is ________ (rounded off to one decimal place). 𝑐𝑙 0.2 0.4 0.6 0.8 𝑐𝑚 – 0.02 0 0.02 0.04

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q45

NAT[2 Marks]

Consider a finite wing of aspect ratio 10 with span effectiveness factor 0.95. Its airfoil section has a lift slope of 0.106 per degree and a zero-lift angle of attack of –1.5°. The lift coefficient of the wing at an angle of attack of 3.5° is ________ (rounded off to 2 decimal places).

Explanation

GATE→2026→Aerodynamics→Airfoils and Wings

Q46

NAT[2 Marks]

Thin airfoil theory predicts the zero-lift angle of attack 𝛼𝐿=0 of NACA 2412 airfoil as −2.1°. The corresponding prediction of 𝛼𝐿=0 for NACA 5410 airfoil is ________ degrees (rounded off to 1 decimal place).

Explanation

GATE→2025→Aerodynamics→Airfoils and Wings

Q47

MCQ[1 Mark]

For a NACA 4415 airfoil, the location of maximum camber, as a fraction of the chord length from the leading edge, is ______.

(A)

0.44

(B)

0.40

(C)

0.15

(D)

0.04

Explanation

GATE→2025→Aerodynamics→Airfoils and Wings

Q48

MCQ[1 Mark]

A positively cambered airfoil is placed in a uniform flow (velocity, U∞) at its zero-lift angle of attack. M is the corresponding pitching moment. Which one of the following representations accurately describes this scenario?

(A)

(B)

(C)

(D)

Explanation

GATE→2025→Aerodynamics→Airfoils and Wings

Q49

MCQ[2 Marks]

A lifting surface has a spanwise circulation distribution of Γ(𝜃) = 𝐴sin3𝜃 (where 𝐴≠0) over its span − 𝑏 2 ≤𝑦≤ 𝑏 2, and 𝑦= − 𝑏 2 cos 𝜃 is the spanwise coordinate. Furthermore, the downwash varies along the span as 𝑤(𝜃) = 𝑉∞( 3𝐴sin 3𝜃 sin 𝜃), where 𝑉∞ is the freestream velocity. Which one of the following options represents the total lift (𝐿) and induced drag (𝐷𝑖)?

(A)

𝐿= 0 and 𝐷𝑖= 0

(B)

𝐿= 0 and 𝐷𝑖≠0

(C)

𝐿≠0 and 𝐷𝑖= 0

(D)

𝐿≠0 and 𝐷𝑖≠0

Explanation

GATE→2025→Aerodynamics→Airfoils and Wings

Q50

NAT[2 Marks]

A rectangular wing of 1.2 m chord length and aspect ratio 5 is tested in a wind tunnel at an air speed of 60 m/s. The density and the dynamic viscosity of air are 1.3 kg/m3 and 1.8×10-5 kg/m-s, respectively. A second rectangular wing of the same span, but with an aspect ratio of 6, is to be tested in the same tunnel at the same Reynolds number. The air speed at which the second test should be performed is _______ m/s (answer in integer).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q51

MCQ[1 Mark]

Consider the free vibration responses P, Q, R and S (shown in the figure) of a single degree of freedom spring-mass-damper system with the same initial conditions. For the different damping cases listed below, which one of the following options is correct? 1. Overdamped 2. Underdamped 3. Critically damped 4. Undamped

(A)

P – 1, Q – 4, R – 2, S – 3

(B)

P – 1, Q – 2, R – 4, S – 3

(C)

P – 3, Q – 4, R – 2, S – 1

(D)

P – 3, Q – 2, R – 4, S – 1

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q52

MCQ[1 Mark]

A surrogate liquid hydrocarbon fuel, approximated as C10H12, is being burned in a land-based gas turbine combustor with dry air (79% N2 and 21% O2 by volume). How many moles of dry air are required for the stoichiometric combustion of the surrogate fuel with dry air at atmospheric temperature and pressure?

(A)

61.9

(B)

30.95

(C)

13

(D)

10

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q53

MCQ[1 Mark]

In an airbreathing gas turbine engine, the combustor inlet temperature is 600 K. The heating value of the fuel is 43.4 × 106 J/kg. Assume Cp to be 1100 J/kg K for air and burned gases, and fuel-air ratio f << 1.0. Neglect kinetic energy at the inlet and exit of the combustor and assume 100% burner efficiency. What is the fuel-air ratio required to achieve 1300 K temperature at the combustor exit?

(A)

0.0177

(B)

0.0215

(C)

0.0127

(D)

0.0277

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q54

MCQ[1 Mark]

Which one of the following figures represents the drag polar of a general aviation aircraft?

(A)

(B)

(C)

(D)

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q55

MCQ[1 Mark]

In the context of steady, inviscid, incompressible flows, consider the superposition of a uniform flow with speed U along the positive x-axis (from left to right), and a source of strength Λ located at the origin. Which one of the following statements is NOT true regarding the location of the stagnation point of the resulting flow?

(A)

It is located to the left of the origin

(B)

It moves closer to the origin for increasing Λ, while U is held constant

(C)

It moves closer to the origin for increasing U, while Λ is held constant

(D)

It is located along the x-axis

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q56

MCQ[1 Mark]

On Day 1, an aircraft flies with a speed of 𝑉1 m/s at an altitude where the temperature is T1 K. On Day 2, the same aircraft flies with a speed of √1.2 𝑉1 m/s at an altitude where the temperature is 1.2 T1 K. How does the Mach number M2 on Day 2 compare with the Mach number M1 on Day 1? Assume ideal gas behavior for air. Also assume the ratio of specific heats and molecular weight of air to be the same on both the days.

(A)

M2 = 0.6 M1

(B)

M2 = M1

(C)

M2 = 1 √1.2 M1

(D)

M2 = √1.2 M1

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q57

MCQ[1 Mark]

Consider a steady, isentropic, supersonic flow (Mach number M > 1) entering a Convergent-Divergent (CD) duct as shown in the figure. Which one of the following options correctly describes the flow at the throat?

(A)

Can only be supersonic

(B)

Can only be sonic

(C)

Can either be sonic or supersonic

(D)

Can only be subsonic

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q58

MCQ[1 Mark]

Consider steady, incompressible, inviscid flow past two airfoils shown in the figure. The coefficient of pressure at the trailing edge of the airfoil with finite angle, shown in figure (I), is 𝐶𝑃𝐼 while that at the trailing edge of the airfoil with cusp, shown in figure (II), is 𝐶𝑃𝐼𝐼. Which one of the following options is TRUE?

(A)

𝐶𝑃𝐼< 1, 𝐶𝑃𝐼𝐼< 1

(B)

𝐶𝑃𝐼= 1, 𝐶𝑃𝐼𝐼= 1

(C)

𝐶𝑃𝐼= 1, 𝐶𝑃𝐼𝐼< 1

(D)

𝐶𝑃𝐼< 1, 𝐶𝑃𝐼𝐼= 1

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q59

MSQ[1 Mark]

Which of the following options is/are correct?

(A)

The stress-strain graph for a nonlinear elastic material is as shown in the figure

(B)

Material properties are independent of position in a homogeneous material

(C)

An isotropic material has infinitely many planes of material symmetry

(D)

The stress-strain graph for a linear elastic material is

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q60

MSQ[1 Mark]

Which of the following statements is/are correct about a satellite moving in a geostationary orbit?

(A)

The orbit lies in the equatorial plane

(B)

The orbit is circular about the center of the Earth

(C)

The time period of motion is 90 minutes

(D)

The satellite is visible from all parts of the Earth

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q61

MSQ[1 Mark]

In a conventional configuration airplane, the rudder can be used:

(A)

to overcome adverse yaw during a turning maneuver

(B)

to overcome yawing moment due to failure of one engine in a multi engine airplane

(C)

for landing the airplane in crosswind conditions

(D)

for enhancing longitudinal stability

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q62

MSQ[1 Mark]

Which of the following statements about a general aviation aircraft, while operating at point Q in the V-n diagram, is/are true?

(A)

The aircraft has the highest turn rate

(B)

The aircraft has the smallest turn radius

(C)

The aircraft is flying with minimum drag

(D)

The aircraft is operating at 𝐶𝐿,𝑚𝑎𝑥

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q63

NAT[1 Mark]

An airplane experiences a net vertical ground reaction of 15000 N during landing. The weight of the airplane is 10000 N. The landing vertical load factor, defined as the ratio of inertial load to the weight of the aircraft, is __________ (rounded off to 1 decimal place).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q64

NAT[1 Mark]

An aircraft with a turbojet engine is flying with 250 m/s speed at an altitude, where the density of air is 1 kg/m3. The inlet area of the engine is 1 m2. The average velocity of the exhaust gases at the exit of the nozzle, with respect to aircraft, is 550 m/s. Assume the engine exit pressure is equal to the ambient pressure and the fuel-air ratio is negligible. The uninstalled thrust produced by the engine at these conditions is _________ N (rounded off to the nearest integer).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q65

NAT[1 Mark]

Using thin airfoil theory, the lift coefficient of a NACA 0012 airfoil placed at 5o angle of attack in a uniform flow is _____________ (rounded off to 2 decimal places).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q66

MCQ[2 Marks]

As per the International Standard Atmosphere model, which one of the following options about density variation with increase in altitude in the isothermal layer is correct?

(A)

remains constant

(B)

increases linearly

(C)

decreases linearly

(D)

decreases exponentially

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q67

MCQ[2 Marks]

A multistage axial compressor, with overall isentropic efficiency of 0.83, is used to compress air at a stagnation temperature of 300 K through a pressure ratio of 10:1. Each stage of the compressor is similar, and the stagnation temperature rise across each compressor stage is 20 K. Assume Cp = 1005 J/kg K and  = 1.4 for air. How many stages are there in the compressor?

(A)

17

(B)

13

(C)

19

(D)

11

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q68

MCQ[2 Marks]

An aircraft with a turbojet engine is flying at 250 m/s. The uninstalled thrust produced by the engine is 60000 N. The heating value of the fuel is 44 × 106 J/kg. The engine has a thermal efficiency of 35% while burning the fuel at a rate of 3 kg/s. Assume the engine exit pressure to be equal to the ambient pressure. What is the propulsion efficiency of the engine under these conditions (in percentage)?

(A)

32.5

(B)

35.0

(C)

11.4

(D)

92.4

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q69

MCQ[2 Marks]

Consider a flat plate, with a sharp leading edge, placed in a uniform flow of speed U. The direction of the free-stream flow is aligned with the plate. Assume that the flow is steady, incompressible and laminar. The thickness of the boundary layer at a fixed stream-wise location L from the leading edge of the plate is δ. Which one of the following correctly describes the variation of δ with U?

(A)

δ ∝ U

(B)

δ ∝ U 3/2

(C)

δ ∝ U 1/2

(D)

δ ∝ U −1/2

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q70

MCQ[2 Marks]

Shock structures for flow at three different Mach numbers over a given wedge are shown in the figure below. Assuming that only the weak shock solutions are possible for the attached oblique shocks, which one of the following options is TRUE?

(A)

M1 < M2 < M3

(B)

M1 > M2 > M3

(C)

M1 < M3< M2

(D)

M3 < M1 < M2

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q71

MCQ[2 Marks]

Air flowing at Mach number M = 2 from left to right accelerates to M = 3 across an expansion corner as shown in the figure. What is the value of 𝛿 (the angle between the Forward and Rearward Mach lines) in degrees? The values of the Prandtl-Meyer functions are 𝜈(3) = 49.76o and 𝜈(2) = 26.38o.

(A)

23.38

(B)

19.47

(C)

53.38

(D)

33.91

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q72

MSQ[2 Marks]

Which of the following statements about absolute ceiling and service ceiling for a piston-propeller aircraft is/are correct?

(A)

The altitude corresponding to absolute ceiling is higher than that for service ceiling

(B)

At the absolute ceiling, the power required for cruise equals the maximum power available

(C)

The altitude corresponding to absolute ceiling is lower than that for service ceiling

(D)

At the service ceiling, the maximum rate of climb is 50 ft/min

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q73

MSQ[2 Marks]

For an airplane having directional / weathercock static stability, which of the following options is/are correct?

(A)

The airplane when disturbed in yaw, from an equilibrium state, will experience a restoring moment

(B)

The variation of yawing moment coefficient (𝐶𝑛) with sideslip angle (β) for the airplane will look like

(C)

The airplane will always tend to point into the relative wind

(D)

The airplane when disturbed in yaw will return to equilibrium state in a finite amount of time after removing the disturbance

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q74

MSQ[2 Marks]

Which of the following statements is/are TRUE for an axial turbine?

(A)

For a fixed rotational speed, the mass flow rate increases with increase in the flow coefficient

(B)

The absolute stagnation enthalpy of the flow decreases across the nozzle row

(C)

The relative stagnation enthalpy remains unchanged through the rotor

(D)

For a fixed rotational speed, the mass flow rate remains unchanged with a change in the flow coefficient

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q75

MSQ[2 Marks]

Which of the following statements is/are TRUE for a single stage axial compressor?

(A)

Starting from design condition and keeping the mass flow rate constant, if the blade RPM is increased, the compressor rotor may experience positive incidence flow separation (actual relative flow angle greater than the design blade angle)

(B)

Starting from design condition at the same blade RPM, if the mass flow rate is increased, the compressor rotor may experience positive incidence flow separation (actual relative flow angle greater than the design blade angle)

(C)

Keeping the mass flow rate constant, if the blade RPM is increased, the compressor may experience surge

(D)

At the same blade RPM, if the mass flow rate is increased, the compressor may experience surge

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q76

NAT[2 Marks]

A chemical rocket with an ideally expanded flow through the nozzle produces 5 × 106 N thrust at sea level. The specific impulse of the rocket is 200 s and acceleration due to gravity at the sea level is 9.8 m/s2. The propellent mass flow rate out of the rocket nozzle is _________ kg/s (rounded off to the nearest integer).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q77

NAT[2 Marks]

A centrifugal compressor is designed to operate with air. At the leading edge of the tip of the inducer (eye of the impeller), the blade angle is 45o, and the relative Mach number is 1.0. The stagnation temperature of the incoming air is 300 K. Consider  = 1.4. Neglect pre-whirl and slip. The inducer tip speed is ________ m/s (rounded off to the nearest integer).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q78

NAT[2 Marks]

Consider the following Fanno flow problem: Flow enters a constant area duct at a temperature of 273 K and a Mach number 0.2 and eventually reaches sonic condition (Mach number =1) due to friction. Assume 𝛾= 1.4. The static temperature at the location where sonic condition is reached is_____________ K (rounded off to 2 decimal places).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q79

NAT[2 Marks]

For an aircraft moving at 4 km altitude above mean sea level at a Mach number of 0.2, the ratio of equivalent air speed to true air speed is _______ (rounded off to 2 decimal places). The density of air at mean sea level is 1.225 kg/m3 and at 4 km altitude is 0.819 kg/m3.

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q80

NAT[2 Marks]

The figure (not to scale) shows a control volume to estimate the forces on the airfoil with elliptic cross-section. Surfaces 2 and 3 are streamlines. Velocity profiles are measured at the upstream end (surface 1) and at the downstream end (surface 4) of the control volume. The drag coefficient for the airfoil is defined as Cd = 𝐷 1 2 𝜌 𝑈∞ 2 𝑐 , where D is the drag force on the airfoil per unit span and  is the density of the air. The static pressure, p, is constant over the entire surface of the control volume. Assuming the flow to be incompressible, two-dimensional and steady, the Cd for the airfoil is _________ (rounded off to 3 decimal places).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q81

NAT[2 Marks]

An airplane of mass 1000 kg is in a steady level flight with a speed of 50 m/s. The wing has an elliptic planform with a span of 20 m and planform area 31.4 m2. Assuming the density of air at that altitude to be 1 kg/m3 and acceleration due to gravity to be 10 m/s2, the induced drag on the wing is _________ N (rounded off to 1 decimal place).

Explanation

GATE→2024→Aerodynamics→Airfoils and Wings

Q82

NAT[2 Marks]

It is desired to estimate the aerodynamic drag, D, on a car traveling at a speed of 30 m/s. A one-third scale model of the car is tested in a wind-tunnel following the principles of dynamic similarity. The drag on the scaled model is measured to be Dm. The ratio D/Dm is _________ (rounded off to 1 decimal place).

Explanation

GATE→2023→Aerodynamics→Airfoils and Wings

Q83

MCQ[1 Mark]

The figures shown in the options are schematics of airfoil shapes (not to scale). For a civilian transport aircraft designed for a cruise Mach number of 0.8, which among them is aerodynamically best suited as a wing section?

(A)

[Visual option A — diagram not captured in source JSON]

(B)

[Visual option B — diagram not captured in source JSON]

(C)

[Visual option C — diagram not captured in source JSON]

(D)

[Visual option D — diagram not captured in source JSON]

Explanation

GATE→2023→Aerodynamics→Airfoils and Wings

Q84

NAT[2 Marks]

o . A thin cambered airfoil has lift coefficient lc = 0 at an angle of attack α= −1.1 o is _______. Assuming that stall occurs at much larger α, the lc at α= 4 (round off to two decimal places)

Explanation

GATE→2022→Aerodynamics→Airfoils and Wings

Q85

MSQ[1 Mark]

NACA 2412 airfoil has

(A)

4% maximum camber with respect to chord

(B)

maximum camber at 40% chord

(C)

12% maximum thickness to chord ratio

(D)

maximum camber at 20% chord

Explanation

GATE→2022→Aerodynamics→Airfoils and Wings

Q86

NAT[2 Marks]

Consider a circulation distribution over a finite wing given by $\Gamma(y) = \Gamma_0(1 - 2|y|/b)$ for $|y| \le b/2$. Span $b = 10\text{ m}$, $\Gamma_0 = 20\text{ m}^2/s$, $\rho = 1.2\text{ kg/m}^3$, $U_{\infty} = 80\text{ m/s}$. Lift over the wing is ______ N.

Explanation

GATE→2022→Aerodynamics→Airfoils and Wings

Q87

NAT[2 Marks]

Consider a thin symmetric airfoil at 2 degree angle of attack in a uniform flow at $50\text{ m/s}$. The pitching moment coefficient about its leading edge is ______ (round off to three decimal places).

Explanation

Potential Flow and Viscous Flows

11 Questions

GATE→2026→Aerodynamics→Potential Flow and Viscous Flows

Q88

MCQ[1 Mark]

In fluid dynamics, d’Alembert’s paradox refers to which one of the following?

(A)

Deviation of drag from 𝐷 ∝ 𝑣 2 at very low speeds

(B)

Deviation of drag from 𝐷 ∝ 𝑣 2 at high subsonic speeds

(C)

Prediction of zero drag by potential flow theory

(D)

Presence of shocks in transonic flows

Explanation

GATE→2026→Aerodynamics→Potential Flow and Viscous Flows

Q89

MCQ[1 Mark]

The velocity potential function (𝜑) given below represents which one of the following? 𝜑 = 5𝑥 − 12𝑦

(A)

Doublet

(B)

Irrotational vortex

(C)

Source

(D)

Uniform flow

Explanation

GATE→2026→Aerodynamics→Potential Flow and Viscous Flows

Q90

MSQ[2 Marks]

Consider the flow over an oval modeled using the elementary potential flows as shown below. 𝑈 represents uniform flow velocity and 𝛤 represents circulation around an irrotational line vortex. Which of the following statements is/are TRUE for this model?

(A)

Increasing 𝑈 enlarges the oval

(B)

Increasing 𝛤 enlarges the oval

(C)

Interchanging the sense of the two vortices does not alter the oval

(D)

Moving the vortices too far apart causes the oval to break up

Explanation

GATE→2025→Aerodynamics→Potential Flow and Viscous Flows

Q91

MCQ[1 Mark]

For a two-dimensional incompressible flow over a flat plate, the laminar boundary layer thickness at a distance 𝑥 from the leading edge is 𝛿. If 𝑅𝑒𝑥 is the Reynolds number defined based on length scale x, ( 𝛿 𝑥) is proportional to ______.

(A)

𝑅𝑒𝑥 −1/2

(B)

𝑅𝑒𝑥 −1

(C)

𝑅𝑒𝑥 −3/2

(D)

𝑅𝑒𝑥 −2

Explanation

GATE→2025→Aerodynamics→Potential Flow and Viscous Flows

Q92

MCQ[1 Mark]

Consider a pair of point vortices with clockwise circulation Γ each. The distance between their centers is 𝑎, as shown in the figure. Assume two-dimensional, incompressible, inviscid flow. Which one of the following options is correct?

(A)

The vortices translate downwards together with a velocity Γ 2𝜋𝑎 .

(B)

The vortices translate upwards together with a velocity Γ 2𝜋𝑎 .

(C)

The vortices rotate clockwise around each other about their centroid O.

(D)

The vortices rotate counter-clockwise around each other about their centroid O.

Explanation

GATE→2025→Aerodynamics→Potential Flow and Viscous Flows

Q93

NAT[1 Mark]

The lift per unit span for a spinning circular cylinder in a potential flow is 6 N/m. The free-stream velocity is 30 m/s, and the density of air is 1.225 kg/m3. The circulation around the cylinder is ____ m2/s (rounded off to two decimal places).

Explanation

GATE→2023→Aerodynamics→Potential Flow and Viscous Flows

Q94

MCQ[1 Mark]

A two-dimensional potential flow solution for flow past an airfoil has a streamline pattern as shown in the figure. Which of the following conditions is additionally required to satisfy the Kutta condition?

(A)

Addition of a source of strength Q  0

(B)

Addition of a source of strength Q  0

(C)

Addition of a circulation of strength  0 (counter-clockwise)

(D)

Addition of a circulation of strength  0 (clockwise) Aerospace Engineering (AE)

Explanation

GATE→2023→Aerodynamics→Potential Flow and Viscous Flows

Q95

MCQ[1 Mark]

Consider the Blasius solution for the incompressible laminar flat plate boundary layer. Among the following options, select the correct relation for the development of the momentum thickness θ with distance x from the leading edge along the length of the plate.

(A)

θ x 2 3

(B)

θ x1 2

(C)

θ x1 7

(D)

θ x −2 3

Explanation

GATE→2023→Aerodynamics→Potential Flow and Viscous Flows

Q96

MCQ[1 Mark]

In a two-dimensional potential flow, the doublet is a limit of the superposition of

(A)

a uniform stream and a source

(B)

a source and a sink of equal strength

(C)

a uniform stream and a sink

(D)

a source and a vortex Aerospace Engineering (AE)

Explanation

GATE→2023→Aerodynamics→Potential Flow and Viscous Flows

Q97

NAT[2 Marks]

In a potential flow, a uniform stream of strength U directed along the x-axis and  − − four line sources (2-dimensional) of strengths , , , are placed along 2 3 4 5 the x-axis at x = 0, 1, 2 and 3, respectively. The strength of an additional line source to be placed at x = 4 such that a closed streamline encircles all five sources is _____. (round off to two decimal places).

Explanation

GATE→2022→Aerodynamics→Potential Flow and Viscous Flows

Q98

MCQ[1 Mark]

Consider a two-dimensional potential flow over a cylinder. If the freestream speed is $U_{\infty}$, the maximum speed on the cylinder surface is

(A)

U_inf / 2

(B)

3 U_inf / 2

(C)

2 U_inf

(D)

4 U_inf / 3

Explanation

Wind Tunnel Testing

1 Question

GATE→2026→Aerodynamics→Wind Tunnel Testing

Q99

NAT[1 Mark]

The vortex shedding frequency behind a landing gear model is found to be 50 Hz when tested in a wind tunnel operating at 5 m/s. If the actual landing gear size is 10 times that of the model, and it is designed to operate at 50 m/s, then the expected vortex shedding frequency behind it is ________ Hz (rounded off to the nearest integer).

Explanation