Questions and Answers of Fundamentals Of Aerodynamics

What are the similarities and differences between the rotation motion of micro fluid elements and the rotation motion of rigid bodies?
Derive an expression for Helmholtz’s velocity decomposition theorem.
What is the physical meaning of divergence of velocity field? In the process of fluid motion, the divergence can be greater than zero, less than zero and equal to zero, please explain the physical
What is the expression of the law of conservation of mass in fluid motion? If the fluid particles do not have continuity conditions, how to express the conservation of mass?
If there is a mass source in the control volume, how can we express the law of conservation of mass?
Use the continuity equation to prove that the density decreases when the volume of the micro fluid elements expands. The density increases when the volume is compressed. The volume doesn’t change
In an ideal fluid, what are the main factors that change the motion of a fluid particle?
How to change particle velocity in an isobaric flow field? How to change the velocity of a fluid particle regardless of mass force?
Combined with Euler’s differential equations of motion, explain how the pressure changes when the velocity increases along the pipeline with hori-zontal contraction. If the pipe is expanded
Try to derive the Lagrangian differential equations of fluid motion?
Please explain the physical meaning of curl of velocity field? How does it relate to the angular velocity of the fluid mass about its own axis? And write the curl expression.
The flow field where the rotational angular velocity is equal to zero is called a non-swirling flow field. Please use the Stokes formula to prove that the line integral of the velocity is independent
At the same spacing, what’s the relationship between the magnitude of the velocity potential change and the magnitude of the velocity?
The fluid flows along the horizontal expansion pipe and the contraction pipe. Describe the relationship between acceleration and pressure from Euler’s equation. What causes the acceleration of a
Can you write Euler’s equation in vector form? The projection form along the flow direction?
Write down the expressions for the components of the Euler equation along the x direction.
Please write down the Gromyko-Lamb equation in the x direction. Write down the Gromyko-Lamb equation in vector form.
What are the conditions for the Existence of Bernoulli integrals? Write the ideal incompressible fluid, with gravity as mass force, steady flow, energy equation per unit mass, and explain the
Write the energy equation for an ideal incompressible fluid, without mass force, steady flow, unit mass, and explain the physical meaning of each.
If we assume that the relationship between pressure and density is p equals upper C rho Superscript gamma p equals upper C rho Superscript gamma p equals upper C rho Superscript gammaCρp equals
What is the velocity change of flow with and without mass force? Please use specific examples to illustrate this.
What is a system? What is the control volume? Explain the differences between the system and the control volume.
The physical meaning of Reynolds transport equation? What are the conditions for the Reynolds transport equation?
Write down the momentum integral equation and explain the physical meaning of the terms?
Write down the energy integral equation, and explain the physical meaning of the terms?
What are ideal positive pressure fluid, steady flow and mass force potential?
For pipe flow, can you give a simplified form of the Reynolds transport equation?
Under the condition of ideal positive pressure fluid and potential mass force, vorticity is strongly conserved. Explain how a viscous fluid flows around a vortex.
What is a vortex? What are vorticity, eddy flux and velocity circulation?
Explain the physical meaning of Stokes integral? In any closed curve, the velocity circulation is equal to zero, why can’t it be judged that there is no vortex field in this region?
How to characterize the rotation speed of a group of fluid masses?
What is Helmholtz’s conservation of three vortices?
Why a vortex tube cannot be interrupted in a fluid.
Why can tornadoes pull up big trees? How to characterize the strength of the tornado?
How does the wingtip vortex in flight affect the lift of the aircraft?
How does the leading-edge vortex of modern fighter wings affect the lift?
How to calculate the vorticity flux in a vortex tube if the vorticity distribution is not uniform?
Describe the expression of the induced velocity of an infinitely long cylindrical vortex perpendicular to the plane of symmetry of the vortex axis.
The following velocity fieldsFind the acceleration at the point (2, 2, 1) at t = 3. u2t+2x+2y v=t-y+z w=1+xz
A section of U-shaped pipe. The inner diameter of the pipe is 0.5 m. Air enters one section of the pipe at an average speed of 100 m/s and flows out the other section at the same speed, but in the
Through the flow, the adjusting valve is gradually closed, so that the flow is linearly reduced, the flow is reduced to zero in 20 s. Try to find the acceleration at point A on the axis of the pipe
Let the following functions represent the three fractional velocities of the flow:where k is a constant. Which cases represent incompressible flow. (1) u=kx, v = -ky, w = 0 (2) u=kx, v=-ky, w=kx (3)
There is a vent with an area 0.4 m2 on the wall of the air supply duct. Try to find the average velocity v of the outlet flow.
If gas is put in a closed container, it will expand and fill the container entirely and total pressure will drop. (True/False)
The air can hold more water vapor at a lower temperature.(True/False)
What is the composition of dry air?
What is the standard temperature lapse rate?
What is standard pressure in pounds per square inch (psi) at sea level on a standard day?
Define and describe pressure altitude.
Define and describe density altitude. What effect does density altitude have on aircraft performance?
What three factors change air density?
How does humidity affect aircraft performance? Do performance charts account for humidity?
When are the four forces in flight in equilibrium?
Explain why lift is considered a mechanical force.
What is the Magnus effect?
Describe viscosity’s effects on the boundary layer.
Draw a basic cambered airfoil and label the chord line, relative wind, AOA, stagnation point, lift vector, and weight vector.
Describe parasite drag.
Explain form drag.
Explain skin friction drag.
Describe cooling and leakage drag.
What is induced AOA?
Explain induced drag and how the pilot changes it during flight.
What aerodynamic factors affect induced drag?
Describe propeller efficiency and why it’s important.
What is the difference between a fixed-pitch propeller and a controllable-pitch propeller?
As velocity increases, the propeller blades’ relative wind moves in relation to the chord line. Does the AOA increase or decrease? What effect does this have on propeller RPM?
Describe propeller twist and its purpose.
What are the four left turning tendencies?
Explain in simple terms why an aircraft climbs.
What is the difference between best angle of climb (VX) and best rate of climb (VY)?
Explain the difference between range and endurance.
What are some issues with glide ratio charts?
How do runway surface conditions affect takeoff and landing performance?
Describe hydroplaning. How can pilots calculate the minimum speed at which hydroplaning will begin?
What factors affect takeoff performance?
How much does a tailwind increase landing distance?
Describe static and dynamic stability.
Explain the different types of static and dynamic stability.
Describe the difference between maneuverability andcontrollability.
What is speed stability?
Explain what type of stability the aircraft would exhibit if the CG is behind the CL.
How do the engine nacelles and fuselage affect aircraft stability?
What is the primary source of directional stability in an aircraft?
What are the three factors that affect lateral stability?
Describe what limits an aircraft’s ability to maneuver.
When flying at the minimum steady flight speed in level flight, if the aircraft enters a level turn without increasing its speed, the aircraft will _____ as the angle of attack is increased to
If the limit load factor is exceeded, the aircraft will experience structural failure. (True/False)
What is the primary reason power must be added in a turn to maintain airspeed?
Why is the application of power used to assist in the recovery of a stall, but not a spin?
In a spin to the left, which wing has a higher angle of attack?
The force which causes an aircraft to turn is controlled by which primary control surface: elevator, aileron, or rudder?
As long as a high airspeed is maintained, the aircraft cannot stall while maneuvering. (True/False)
Explain how wing washout is used to produce a progressive stall pattern (root-to-tip).
Identify the most important variable in determining the speed of sound in our atmosphere.
Why is the speed of sound slower at 30,000 feet than at 10,000 feet?
What is the generally accepted airspeed region for subsonic flight?
What is the generally accepted airspeed region for transonic flight?
What is the generally accepted airspeed region for supersonic flight?
Explain the term “critical Mach number.”

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