(Aerodynamics MCQs Aeronautical Engineering

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What does Bernoulli’s principle state about fluid flow? a) Increase in velocity leads to an increase in pressure b) Decrease in velocity leads to an increase in pressure c) Increase in velocity leads to a decrease in pressure d) Pressure and velocity are independent of each other Answer: c) Increase in velocity leads to a decrease in pressure The angle of attack is defined as: a) The angle between the wing chord line and the relative airflow b) The angle between the aircraft longitudinal axis and the horizontal plane c) The angle between the aircraft heading and the wind direction d) The angle between the wing’s leading edge and the trailing edge Answer: a) The angle between the wing chord line and the relative airflow The term “lift coefficient” (Cl) is used to describe: a) The lift force relative to the airspeed and wing area b) The drag force relative to the airspeed and wing area c) The ratio of lift to drag d) The rate of change of lift with respect to angle of attack Answer: a) The lift force relative to the airspeed and wing area In subsonic flow, the pressure distribution over an airfoil can be predicted using: a) The Bernoulli equation b) The Navier-Stokes equations c) The Reynolds number d) The Mach number Answer: a) The Bernoulli equation What is the primary purpose of the boundary layer in aerodynamics? a) To increase the lift force b) To reduce the drag force c) To prevent flow separation and maintain smooth airflow d) To increase the aircraft’s speed Answer: c) To prevent flow separation and maintain smooth airflow The “drag coefficient” (Cd) is used to measure: a) The efficiency of an aircraft’s lift-to-drag ratio b) The resistance of an object moving through a fluid c) The rate of change of drag with respect to velocity d) The lift force relative to drag Answer: b) The resistance of an object moving through a fluid In aerodynamics, what does “streamline” refer to? a) The path followed by a fluid particle in steady flow b) The shape of an airfoil c) The direction of the aircraft’s movement d) The orientation of the wing Answer: a) The path followed by a fluid particle in steady flow The term “Mach number” represents: a) The ratio of the flow velocity to the speed of sound in the fluid b) The ratio of the wing area to the aircraft weight c) The ratio of lift to drag d) The rate of change of air pressure with altitude Answer: a) The ratio of the flow velocity to the speed of sound in the fluid What is the “stall” condition in aerodynamics? a) A condition where the aircraft is flying at maximum speed b) A condition where the airflow over the wing separates, causing a loss of lift c) A condition where the aircraft is cruising at a constant altitude d) A condition where the aircraft is experiencing maximum lift Answer: b) A condition where the airflow over the wing separates, causing a loss of lift The “compressibility effect” becomes significant at what Mach number? a) Below Mach 0.3 b) Around Mach 0.6 c) Above Mach 0.8 d) Above Mach 1.0 Answer: d) Above Mach 1.0 The “lift-to-drag ratio” is an important factor in determining: a) The efficiency of an aircraft’s flight b) The amount of fuel required c) The rate of climb d) The maximum speed of the aircraft Answer: a) The efficiency of an aircraft’s flight The “NACA airfoil” series are used to: a) Design and analyze airfoils for various aerodynamic characteristics b) Calculate the lift and drag coefficients for different aircraft c) Determine the speed of sound in different fluids d) Measure the boundary layer thickness Answer: a) Design and analyze airfoils for various aerodynamic characteristics The “boundary layer” thickness increases with: a) Increasing flow velocity b) Increasing surface roughness c) Increasing fluid density d) Increasing altitude Answer: b) Increasing surface roughness In supersonic flow, shock waves are: a) Compression waves that form when an object moves faster than the speed of sound b) Rarefaction waves that form when an object moves slower than the speed of sound c) Sound waves that propagate through a fluid d) Boundary layer separation waves Answer: a) Compression waves that form when an object moves faster than the speed of sound The “Kutta-Joukowski theorem” is used to: a) Determine the lift generated by a rotating airfoil b) Calculate the drag on an aircraft c) Predict the airflow over a stationary wing d) Analyze the compressibility effects in supersonic flow Answer: a) Determine the lift generated by a rotating airfoil What is the main advantage of a high aspect ratio wing? a) Reduced drag and improved lift-to-drag ratio b) Increased maneuverability c) Increased structural strength d) Better low-speed performance Answer: a) Reduced drag and improved lift-to-drag ratio The “wing loading” is defined as: a) The ratio of aircraft weight to wing area b) The ratio of wing span to wing area c) The ratio of lift to drag d) The ratio of airspeed to stall speed Answer: a) The ratio of aircraft weight to wing area The “Induced drag” is primarily caused by: a) The generation of lift and the resulting vortex formation b) The friction between the airfoil and the air c) The surface roughness of the airfoil d) The flow separation over the airfoil Answer: a) The generation of lift and the resulting vortex formation The “Blending” of a wing’s leading edge is done to: a) Reduce the drag and improve the aerodynamic efficiency b) Increase the aircraft’s lift coefficient c) Decrease the aircraft’s stall speed d) Enhance the structural strength of the wing Answer: a) Reduce the drag and improve the aerodynamic efficiency In a wind tunnel test, the “dynamic similarity” between the model and the prototype ensures: a) That the aerodynamic characteristics of both are comparable b) That the physical size of the model is the same as the prototype c) That the model and prototype are made of the same material d) That the wind speed in the tunnel is the same as the prototype’s flight speed Answer: a) That the aerodynamic characteristics of both are comparable The “Navier-Stokes equations” are used to: a) Describe the motion of fluid substances b) Calculate the lift and drag coefficients c) Determine the airflow over a static airfoil d) Measure the boundary layer thickness Answer: a) Describe the motion of fluid substances The “Euler’s equation” in aerodynamics is related to: a) The conservation of momentum in a fluid flow b) The conservation of energy in a fluid flow c) The conservation of mass in a fluid flow d) The conservation of volume in a fluid flow Answer: a) The conservation of momentum in a fluid flow In aerodynamics, “pressure recovery” occurs in: a) Diffusers b) Nozzles c) Compressors d) Turbines Answer: a) Diffusers The “drag divergence Mach number” is: a) The Mach number at which drag increases rapidly with increasing speed b) The Mach number at which lift decreases with increasing speed c) The Mach number at which lift-to-drag ratio is maximized d) The Mach number at which pressure recovery is maximized Answer: a) The Mach number at which drag increases rapidly with increasing speed The “constant-pressure” assumption is valid in which type of flow? a) Compressible flow b) Incompressible flow c) Supersonic flow d) Hypersonic flow Answer: b) Incompressible flow The “shock wave” in supersonic flow causes: a) A sudden increase in pressure and temperature b) A gradual decrease in pressure and temperature c) A steady flow without any pressure change d) A decrease in velocity and an increase in temperature Answer: a) A sudden increase in pressure and temperature “High-speed aerodynamic effects” include: a) Compressibility effects b) Boundary layer separation c) Low-speed drag reduction d) Laminar flow maintenance Answer: a) Compressibility effects The “Mach angle” is: a) The angle between the direction of the shock wave and the direction of the flow b) The angle between the aircraft’s longitudinal axis and the relative airflow c) The angle between the lift force and the drag force d) The angle between the airflow and the wing chord line Answer: a) The angle between the direction of the shock wave and the direction of the flow In an airfoil, “camber” refers to: a) The curvature of the airfoil’s mean line b) The thickness of the airfoil c) The angle of attack of the airfoil d) The shape of the airfoil’s leading edge Answer: a) The curvature of the airfoil’s mean line “Streamlined” bodies are designed to: a) Minimize drag by allowing smooth flow over the surface b) Maximize drag by creating turbulent flow c) Increase lift by altering the airflow direction d) Improve structural strength by reducing aerodynamic forces Answer: a) Minimize drag by allowing smooth flow over the surface The “Reynolds number” is used to describe: a) The ratio of inertial forces to viscous forces in a fluid flow b) The ratio of lift to drag in an aerodynamic system c) The ratio of compressibility effects to temperature effects d) The ratio of pressure to velocity in a compressible flow Answer: a) The ratio of inertial forces to viscous forces in a fluid flow The “flow separation” on an airfoil occurs when: a) The boundary layer loses energy and cannot adhere to the airfoil surface b) The airflow remains attached to the surface of the airfoil c) The lift force exceeds the drag force d) The airfoil’s angle of attack is minimized Answer: a) The boundary layer loses energy and cannot adhere to the airfoil surface In aerodynamics, “suction” refers to: a) The reduction of pressure above an airfoil that contributes to lift b) The increase of pressure below an airfoil that contributes to drag c) The increase in velocity over an airfoil that reduces drag d) The decrease in velocity below an airfoil that reduces lift Answer: a) The reduction of pressure above an airfoil that contributes to lift The “critical Mach number” is defined as: a) The Mach number at which the first shock wave forms on the aircraft b) The Mach number at which drag is minimized c) The Mach number at which the aircraft reaches maximum altitude d) The Mach number at which the lift coefficient is maximized Answer: a) The Mach number at which the first shock wave forms on the aircraft The “angle of incidence” is: a) The angle between the aircraft’s longitudinal axis and the wing chord line b) The angle between the relative airflow and the wing chord line c) The angle between the aircraft’s heading and the wind direction d) The angle between the aircraft’s pitch axis and the horizontal plane Answer: a) The angle between the aircraft’s longitudinal axis and the wing chord line In supersonic aerodynamics, “expansion fans” are: a) Regions where the flow accelerates and pressure decreases b) Regions where the flow decelerates and pressure increases c) Areas where shock waves are formed d) Zones of turbulent flow behind the aircraft Answer: a) Regions where the flow accelerates and pressure decreases The “airfoil lift curve slope” is defined as: a) The rate of change of lift coefficient with respect to angle of attack b) The rate of change of drag coefficient with respect to airspeed c) The rate of change of pressure with respect to angle of attack d) The rate of change of wing loading with respect to airspeed Answer: a) The rate of change of lift coefficient with respect to angle of attack The “drag polar” is a plot of: a) Drag coefficient versus lift coefficient b) Lift coefficient versus airspeed c) Lift versus drag d) Airspeed versus drag Answer: a) Drag coefficient versus lift coefficient The “airfoil thickness-to-chord ratio” influences: a) The amount of lift generated and the drag characteristics b) The wing’s aspect ratio and structural strength c) The aircraft’s maximum speed and climb rate d) The wing’s leading edge shape and angle of attack Answer: a) The amount of lift generated and the drag characteristics In aerodynamics, “induced drag” is: a) The drag that results from the generation of lift b) The drag due to friction between the airfoil and the air c) The drag caused by the flow separation over the airfoil d) The drag resulting from changes in air pressure Answer: a) The drag that results from the generation of lift The “Prandtl-Glauert transformation” is used to: a) Analyze compressible flow effects in subsonic and transonic regimes b) Calculate the lift and drag coefficients in incompressible flow c) Determine the boundary layer behavior in laminar flow d) Predict the shock wave patterns in supersonic flow Answer: a) Analyze compressible flow effects in subsonic and transonic regimes The “lift-off speed” of an aircraft is: a) The speed at which the aircraft generates sufficient lift to become airborne b) The speed at which the aircraft reaches maximum speed c) The speed at which the aircraft achieves cruising altitude d) The speed at which the aircraft can maintain level flight Answer: a) The speed at which the aircraft generates sufficient lift to become airborne The “drag coefficient” for a streamlined body is typically: a) Low b) High c) Unaffected by the shape d) The same as for a blunt body Answer: a) Low The “pitching moment” is: a) The moment about the center of gravity due to aerodynamic forces on the airfoil b) The moment about the aircraft’s longitudinal axis during a turn c) The moment created by the control surfaces during a climb d) The moment experienced due to the aircraft’s weight distribution Answer: a) The moment about the center of gravity due to aerodynamic forces on the airfoil The “Gurney flap” is used to: a) Increase the lift and reduce drag on an airfoil b) Improve the boundary layer attachment on a wing c) Enhance the control authority of an aircraft’s ailerons d) Decrease the aircraft’s takeoff distance Answer: a) Increase the lift and reduce drag on an airfoil The “boundary layer transition” occurs when: a) The flow changes from laminar to turbulent over the airfoil b) The flow changes from turbulent to laminar over the airfoil c) The airflow becomes steady and uniform d) The airfoil experiences maximum lift Answer: a) The flow changes from laminar to turbulent over the airfoil In aerodynamics, “total pressure” is: a) The sum of static pressure and dynamic pressure b) The difference between static pressure and dynamic pressure c) The static pressure multiplied by the dynamic pressure d) The average pressure experienced by the aircraft Answer: a) The sum of static pressure and dynamic pressure The “speed of sound” in air is affected by: a) Temperature and pressure b) The aircraft’s velocity c) The altitude of the aircraft d) The airfoil shape Answer: a) Temperature and pressure In “high-speed flight,” which effect becomes significant? a) Compressibility effect b) Viscous effect c) Boundary layer effect d) Gravitational effect Answer: a) Compressibility effect

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