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FUNDAMENTALS OF AERODYNAMICS

AERODYNAMICS

AERODYNAMICS IS THE STUDY OF THE MOTION OF AIR AND OF THE FORCES ON SOLIDS IN MOTION RELATIVE TO THE AIR.

THE INTERNATIONAL STANDARD ATOSPHERE

The atmosphere is the mechanical mixture of gases surrounding the earth.

ATMOSPHERIC CONSTITUENTS

Nitrogen78.03%

Oxygen20.99%

Argon0.94%

Carbon Dioxide0.03%

Hydrogen0.01%

Helium0.004%

Neon0.0012% and small amount of water vapor

and other gases.

FOUR LAYERS OF EARTHS ATMOSPHERE

Trophosphere

Stratosphere

Ionosphere

Exosphere

STANDARD VALUES FOR AIR AT SEA LEVEL

Pressure

Density

Temperature

Coefficient of Dynamic Viscosity

REGIONS OF THE EARTHS ATMOSPHERE

Tropopause: Going upward from the surface, it is the point where air ceases to cool with height, and becomes almost completely dry.

Sea Level: is a measure of the average height of theocean's surface (such as the halfway point between the mean hightideand the mean low tide)

SEA LEVEL UP TO TROPOPAUSE (11 Km, 36,080 ft)

1. TEMPERATURE VARIATION UP TO TROPOPAUSE

Where:

2. PRESSURE VARIATION UP TO TROPOPAUSE

Where:

3.DENSITY VARIATION UP TO TROPOPAUSE

Where:

ABOVE TROPOPAUSE (11Km) up to STRATOPAUSE (32Km, 104960 ft)

1. TEMPERATURE VARIATION ABOVE TROPOPAUSE (11Km) up to STRATOPAUSE (32Km, 104960 ft)

2. PRESSURE VARIATION ABOVE TROPOPAUSE (11Km) up to STRATOPAUSE (32Km, 104960 ft)

English System

Where:

2. PRESSURE VARIATION ABOVE TROPOPAUSE (11Km) up to STRATOPAUSE (32Km, 104960 ft)

Metric System

Where:

3. DENSITY VARIATION ABOVE TROPOPAUSE (11Km) up to STRATOPAUSE (32Km, 104960 ft)

English System

Where:

3. DENSITY VARIATION ABOVE TROPOPAUSE (11Km) up to STRATOPAUSE (32Km, 104960 ft)

Metric System

Where:

ALTEMETERS

Is a pressure gauge which indicates an altitude in the standard atmosphere corresponding to the measured pressure.

Pressure altitude,

Is the altitude given by an altimeter set to 29.92Hg

Density altitude,

Is the altitude corresponding to a given density in the standard atmosphere.

Temperature altitude,

Is the altitude corresponding to a given temperature in the standard atmosphere.

Example # 1-Calculate the pressure, density and temperature at 11km and 15km altitudes in the standard atmosphere.

For 11km

For 15 km

Example # 2:Find the pressure and Temperature at an altitude where the density is in

Standard atmosphere.

Given:

Standard atmosphere

Required:

P and T

To checked if the density is at any level between Tropopause up to Stratopause

@= 11km

=

=0.362

Note: Density must be lower than 0.362 for us to use the formula of Pressure and Density variation with altitude above Tropopause up to Stratopause

Solution:

ln=ln

To get the Pressure

For Temperature

Example # 3:On a hot day, the measured temperature and pressure are 38C and 29.0 in Hg, respectively. Calculate the density and the density ratio.

Given:

Required:

Solution:

Example # 4: An altimeter reads 11,200 ft when the temperature is 39F. What is the air density and what is the standard altitude?

BASIC AERODYNAMICS PRINCIPLES AND APPLICATION

Continuity Equation

Conservation of mass along a stream tube, such air in a wind tunnel.

Where:

PRINCIPLE OF MASS CONSERVATION (LAW OF CONTINUITY)

The mass of fluids passing one section in one sec must be the same as the mass of fluid passing any other section in one second.

For incompressible fluid, =constant (M