2BAL-EA

A converging-diverging nozzle is primarily used to achieve _______. Subsonic flow only. Supersonic flow. Incompressible flow. Laminar flow only.

At the throat of a De Laval nozzle, the Mach number is _______. Less than 1. Equal to 1. Greater than 1. Zero.

Choked flow occurs when _______. Exit pressure equals ambient pressure. Throat Mach number reaches 1. Flow becomes incompressible. Velocity becomes zero.

In supersonic flow, the diverging section of a nozzle causes velocity to _______. Decrease. Increase. Remain constant. Become zero.

The main function of a supersonic wind tunnel is to _______. Reduce turbulence only. Simulate high Mach number flow. Increase viscosity. Eliminate compressibility.

Mach number is defined as _______. Velocity / pressure. Velocity / density. Velocity / speed of sound. Speed of sound / velocity.

Sonic velocity in air depends primarily on _______. Pressure. Temperature. Density. Viscosity.

A normal shock wave causes Mach number to _______. Increase. Decrease. Remain constant. Become zero.

Ideal nozzle flow assumes _______. Viscous flow. Heat loss. Isentropic conditions. Turbulent losses.

Choking in a nozzle is controlled by _______. Exit area only. Back pressure and stagnation conditions. Only temperature. Only density.

A supersonic wind tunnel requires _______. Only fan. High-pressure reservoir. Low-speed diffuser only. No nozzle.

The test section of a supersonic wind tunnel is _______. Subsonic. Supersonic. Incompressible. Turbulent only.

The diffuser in a wind tunnel is used to _______. Increase Mach number. Recover static pressure. Create shocks. Increase velocity.

Stagnation pressure is _______. Static pressure only. Dynamic pressure only. Total pressure. Ambient pressure.

A reservoir in wind tunnel design provides _______. Low energy air. High energy air supply. Turbulence only. Vacuum conditions.

At Mach 1, flow is _______. Subsonic. Sonic. Supersonic. Turbulent.

As Mach number increases, density generally _______. Increases. Decreases. Remains constant. Becomes infinite.

Total enthalpy in ideal flow is _______. Variable. Constant. Zero. Negative.

Shock waves are _______. Isentropic. Non-isentropic. Reversible. Frictionless.

The area-Mach relation applies to _______. Incompressible flow. Compressible isentropic flow. Only laminar flow. Only turbulent flow.

In a converging–diverging nozzle, the flow becomes sonic (Mach 1) at the ________ section. Throat section. Exit section. Inlet section. Diffuser section.

What condition is required for choked flow in a converging–diverging nozzle?. Back pressure equals inlet pressure. Back pressure is lower than critical pressure ratio. Back pressure is higher than stagnation pressure. No pressure difference exists.

The diverging section of a De Laval nozzle is used to ________. Slow subsonic flow. Increase supersonic velocity. Maintain constant pressure. Remove shock waves.

A supersonic wind tunnel test section is designed to maintain ________. Unsteady turbulent flow. Supersonic uniform flow. Incompressible flow. Separated flow.

Stagnation temperature is the temperature when flow velocity is ________. Maximum. Zero. Supersonic. Turbulent.

A supersonic diffuser is used to ________. Increase Mach number. Convert velocity to pressure. Generate thrust. Create shock waves.

Critical pressure ratio determines whether flow ________. Becomes turbulent. Reaches Mach 1. Stops completely. Becomes incompressible.

Shock waves in a nozzle cause ________. Pressure drop and velocity rise. Pressure rise and energy loss. Isentropic flow. No change.

The settling chamber function is to ________. Increase turbulence. Stabilize airflow. Increase Mach number. Create shock waves.

The contraction section of a wind tunnel ________. Slows airflow. Accelerates airflow. Creates shocks. Stops flow.

In a C-D nozzle, if the exit pressure is higher than ambient pressure, what condition is occurring?. Overexpanded flow. Underexpanded flow. Perfect expansion. Choked flow only.

Mach number is the ratio of ________. Pressure to density. Velocity to speed of sound. Force to area. Temperature to pressure.

Lower back pressure in a nozzle causes ________. Lower Mach number. Higher exit Mach number. Flow reversal. No change.

A normal shock wave causes flow to change from ________. Subsonic to supersonic. Supersonic to subsonic. Laminar to turbulent. Incompressible to compressible.

The wind tunnel test section provides ________. High turbulence. Uniform flow for testing. Pressure generation. Flow stoppage.

Isentropic flow assumes ________. Heat and friction exist. No heat or friction. Shock dominated flow. Turbulent flow only.

The converging section in subsonic flow ________. Decreases velocity. Increases velocity. Creates shock. Stops flow.

Total pressure in ideal nozzle flow is ________. Constant. Increasing. Decreasing. Zero.

A supersonic wind tunnel nozzle primarily ________. Reduces Mach number. Creates supersonic flow. Stops airflow. Generates heat.

Maximum velocity in a De Laval nozzle occurs at the ________. Inlet. Throat. Diffuser. Exit.

A diffuser in a wind tunnel is used to ________. Increase velocity. Recover pressure. Create shock waves. Reduce temperature only.

In the design of a converging–diverging nozzle, why is the throat considered the most critical section in controlling mass flow?. Because it has maximum area. Because flow becomes choked at Mach 1. Because velocity is zero there. Because pressure is highest at exit.

A supersonic wind tunnel is being designed for Mach 2.5 operation. What nozzle type is required and why is a simple converging nozzle not sufficient?. Converging nozzle, because it increases pressure. Converging–diverging nozzle, because supersonic flow requires expansion. Diffuser only, because it slows flow. Straight duct, because Mach number is irrelevant.

During wind tunnel operation, a normal shock is observed inside the test section. What is the most likely effect on measured aerodynamic data?. Data becomes more accurate. Flow becomes incompressible. Significant distortion of pressure and Mach distribution. Lift increases artificially.

Why must a supersonic nozzle be designed using compressible flow theory rather than incompressible Bernoulli assumptions?. Because velocity is always low. Because density variations become significant at high Mach numbers. Because gravity changes. Because lift is zero.

A wind tunnel settling chamber is installed upstream of the nozzle. What is its primary aerodynamic function?. Increase turbulence for mixing. Reduce flow non-uniformities and turbulence. Increase Mach number directly. Act as a diffuser only.

What happens to static pressure and velocity when air passes through the diverging section of a supersonic nozzle?. Pressure increases, velocity decreases. Both decrease. Pressure decreases, velocity increases. Both remain constant.

What is the physical significance of Mach number in supersonic wind tunnel testing?. It defines aircraft weight. It represents ratio of inertial to acoustic speed. It measures fuel flow. It defines lift coefficient directly.

Why is a diffuser required downstream of a supersonic test section?. To increase Mach number. To recover static pressure and slow flow. To generate thrust. To create shock waves intentionally.

What is the main consequence of a poorly designed nozzle area ratio in supersonic flow?. Improved efficiency. Incorrect Mach number and shock formation. Higher structural strength. Lower temperature only.

In compressible flow, what property remains constant through an ideal nozzle (isentropic assumption)?. Static pressure. Total (stagnation) entropy. Velocity. Density.

Why does flow accelerate in a converging section only when it is subsonic?. Because density is constant. Because pressure increases. Because area reduction increases velocity only in subsonic regime. Because temperature is fixed.

A supersonic inlet must control shock waves carefully. What is the main risk if shocks are not managed properly?. Increase in lift. Loss of total pressure and engine performance. Increase in fuel efficiency. Reduction in drag to zero.

What condition defines a “choked nozzle”?. Flow velocity is zero. Mach number reaches 1 at throat. Pressure is uniform everywhere. Flow is incompressible.

Why is stagnation pressure important in wind tunnel operation?. It determines model weight. It defines available energy for acceleration. It controls aircraft lift directly. It eliminates turbulence.

What happens to temperature in a supersonic expansion through a CD nozzle?. Increases. Decreases. Remains constant. Becomes zero.

Why is a smooth wall surface important inside a supersonic nozzle?. To increase turbulence. To minimize boundary layer losses and shock disturbances. To increase weight. To reduce Mach number.

What is the role of the contraction section in a wind tunnel system?. Reduce velocity. Increase uniformity and accelerate subsonic flow. Create shock waves. Stop airflow.

In supersonic flow, why can disturbances not travel upstream?. Because gravity prevents it. Because flow speed exceeds speed of sound. Because density is zero. Because pressure is constant.

What is the primary aerodynamic purpose of a supersonic wind tunnel test section?. To simulate real flight Mach conditions in controlled environment. To increase aircraft thrust. To measure engine temperature only. To reduce structural weight.

In a converging–diverging nozzle, sonic flow (Mach 1) occurs at the ________. Choked throat. Nozzle exit. Diffuser inlet. Settling chamber.

A supersonic wind tunnel primarily requires a ________ section to ensure uniform flow before the test section. Settling chamber. Diffuser exit. Nozzle exit. Shock tube.

The function of a converging–diverging nozzle is to ________. Accelerate subsonic flow only. Maintain constant velocity. Accelerate flow to supersonic speeds. Increase static pressure.

Choked flow in a nozzle means that mass flow rate is ________. Zero. Maximum possible for given inlet conditions. Dependent on downstream pressure only. Unstable and oscillating.

In supersonic wind tunnels, shock waves in the test section are considered ________. Desirable. Irrelevant. Undesirable disturbances. Required for calibration.

A diffuser in a supersonic wind tunnel is used to ________. Increase Mach number. Recover static pressure after test section. Generate shock waves. Accelerate airflow.

The Mach number at which compressibility effects become significant is approximately ________. 0.1. 0.3. 0.8. 1.5.

In a converging nozzle operating under subsonic conditions, decreasing back pressure causes velocity to ________. Decrease. Remain constant. Increase. Become zero.

The primary purpose of a supersonic wind tunnel is to study ________. Low-speed aerodynamics. Structural loads only. Compressible flow phenomena. Hydrostatic pressure.

When a nozzle is choked, further reduction in back pressure will cause mass flow rate to ________. Increase. Decrease. Remain constant. Become zero.

The relationship between area and Mach number in compressible flow is governed by the ________ equation. Bernoulli. Continuity (incompressible). Area–Mach relation. Hydrostatic.

A supersonic nozzle diverging section causes flow to ________. Decelerate to subsonic. Accelerate to supersonic. Remain incompressible. Stagnate.

Stagnation pressure in a wind tunnel represents ________. Static pressure at exit. Total pressure of moving flow brought to rest isentropically. Shock pressure only. Atmospheric pressure.

The test section of a supersonic wind tunnel must have ________ flow. Turbulent and random. Uniform and steady. High-pressure fluctuating. Viscous dominant.

A normal shock wave causes Mach number to change from ________. Subsonic to supersonic. Supersonic to subsonic. Constant to zero. Subsonic to zero.

In CAAP/FAA aerodynamic principles, isentropic flow assumes ________. Heat transfer occurs. No friction and no heat transfer. Constant pressure. Turbulent mixing.

The purpose of a nozzle throat is to ________. Maximize pressure. Control mass flow rate. Increase turbulence. Reduce velocity.

Supersonic flow is defined as Mach number ________. Less than 1. Equal to 1. Greater than 1. Equal to 0.

A wind tunnel is considered closed-circuit when ________. Air is exhausted to atmosphere. Air is recirculated internally. Only subsonic flow is used. No nozzle is present.

The main reason for using a CD nozzle instead of a converging nozzle alone is to achieve ________. Higher pressure only. Supersonic flow capability. Lower temperature only. Flow separation.

The stagnation temperature in a supersonic flow is ________. Always lower than static temperature. Equal to ambient temperature. Constant along streamline (isentropic flow). Always zero.

A supersonic diffuser is designed to ________. Increase Mach number. Recover pressure from supersonic flow. Generate thrust. Create turbulence.

In wind tunnel design, Reynolds number similarity ensures ________. Same temperature only. Same flow regime behavior. Same pressure only. Same velocity only.

Choked flow depends primarily on ________. Downstream pressure. Upstream stagnation conditions and throat area. Ambient temperature only. Pipe length.

In supersonic flow, an increase in area causes velocity to ________. Decrease. Increase. Remain constant. Become zero.

A Pitot tube in supersonic flow must account for ________. Viscous drag only. Shock wave formation. Gravity effects. Hydrostatic pressure.

The nozzle pressure ratio (NPR) is defined as ________. Exit pressure / inlet pressure. Stagnation pressure / static pressure. Inlet stagnation pressure / ambient pressure. Velocity ratio.

A wind tunnel “start problem” occurs when ________. Flow becomes subsonic unexpectedly. Shock prevents supersonic flow from establishing. Temperature drops too low. Pressure becomes uniform.

The Mach angle is defined as ________. Angle of attack. Angle between flow direction and shock wave. Angle of velocity vector and stagnation line. Angle of nozzle wall.

For ideal supersonic nozzle flow, entropy ________. Increases. Decreases. Remains constant. Becomes infinite.

The function of the contraction section in a wind tunnel is to ________. Increase turbulence. Increase velocity and reduce turbulence. Create shock waves. Reduce stagnation pressure.

In compressible flow, density changes are primarily caused by ________. Gravity. Velocity changes. Magnetic fields. Viscosity only.

The critical pressure ratio determines ________. Wing lift. Onset of choking. Turbine efficiency. Drag coefficient.

A supersonic nozzle design is most sensitive to ________. Color of material. Back pressure variations. Electrical supply. Structural bolts.

Expansion fans in supersonic flow are ________. Shock waves. Smooth expansion waves. Turbulent eddies. Pressure spikes.

The primary measurement in supersonic wind tunnel testing is ________. Weight. Lift and drag forces. Fuel flow. Engine RPM.

In supersonic flow, total pressure across a normal shock ________. Increases. Remains constant. Decreases. Becomes zero.

Wind tunnel blockage effects refer to ________. Electrical interference. Model affecting airflow area. Temperature increase. Noise reduction.

The function of a nozzle in propulsion systems is to ________. Increase pressure. Convert thermal energy into kinetic energy. Stop airflow. Reduce thrust.

The most important design constraint in a supersonic wind tunnel is ________. Color selection. Flow quality and Mach number control. Cabin comfort. Fuel efficiency.