Fundamentals of Aero Exam 1 Practice Exam Theory

Reynolds equation

Re= (pvL)/u

Definition of Reynolds

Simplified from Navier-Stokes, describes how pressure is distributed

Mach Equation

M=V/a

Definition of Mach

Used for scaling movement compared to speed of sound

First relationship to be satisfied for irrotational flow

dw/dy=dv/dz

Second relationship to be satisfied for irrotational flow

dw/dx=du/dz

Third relationship to be satisfied for irrotational flow

dv/dx=du/dz

For a steady flow field, what relationship is always true along a streamline

Velocity vector at every point of the streamline is tangent to the streamline

Is curl a cross or dot product?

Cross product, use matrix

Is divergence a cross or dot product?

Dot, add 3 partials

Gradient form

curl partial vector sum

Diffusion is a measure of what molecular transport phenomena?

Mass

Viscosity, u, is a measure of what molecular transport phenomena?

Momentum

Heat conduction is a measure of what molecular transport phenomena?

Energy

Why are high endurance aircraft often designed with airfoil profiles that promote a large extent of laminar flow?

To reduce drag

What physical principle does the conservation of energy equation relate to for a fluid element?

First law of thermo

How to represent Reynolds in note terminology

inertial/viscous

How to represent Mach in note terminology

inertial/pressure

Why is irrotational flow convenient?

A velocity potential function exists

What type of property is pressure, density, and temperature?

Point

Coefficient of Pressure

(P-P_infinity)/q_infinity

Coefficient of Friction

shear stress/q_infinity

What is q_infinity

Dynamic Pressure

Dynamic pressure equation

0.5rhoV_infinity²

Lift equation

Ncos(angle of attack)-Asin(angle of attack)

Drag equation

Nsin(angle of attack)+Acos(angle of attack)

For 2D foil aerodynamic coefficient equations, what variable do you divide by

C, chord

For 3D foil aerodynamic coefficient equations, what variable do you divide by

S, Area

For 2D coefficient of moment, what do you divide by

c²

For 3D coefficient of moment, what do you divide by

s and l (length)

Is flow outside the BL viscous or inviscid?

Inviscid

What long ass equation includes W dot (work)?

Conservation of energy

What long ass equation includes a sum with viscous forces on the RHS

Conservation of momentum

What equation has 3 forms dependent on flow type and is a sum of 2 terms or dot product equal to 0?

Conservation of Mass / Continuity

Can you predict lift or drag with inviscid flow?

Lift

Which type of flow has a thicker BL?

Turbulent

What physical principle is conservation of momentum representative of?

Newton’s Second Law