Upload
fabian-torres
View
1
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Wind-Tunnels
Citation preview
Wind Tunnel Aerodynamics
By
Dr. Shehret Tilvaldyev
Aerodynamics
The field of science and engineering dealing with the effects of air moving
around solid objects.
Aerodynamicists
Predict what will happen in a given situation using physical laws, math,
wind-tunnels and computers
Air has mass and obeys Newton’s laws.
We must speed-up, slow-down, or change the direction of the air to generate a force.
Look for this in the following examples of aerodynamics…
Wind tunnels are used to predict the amount of force generated by solid objects.
This helps aerodynamicists choose the proper size for things such as wings, spoilers, and parachutes.
Information obtained in wind tunnels is used to improve the design of anything affected by wind.
Wind-Tunnels come in all shapes and sizes…
Open-Return Type Wind-Tunnel
Closed-Return Type Wind-Tunnel
Blow-Down Type Tunnel
Wind Tunnel Test Examples
Similarity Principle
Allows us to test a small model and get information about the full-size object
We’ll use a parachute for example…
Will the egg break?…
Similarity Principle:
For similar shapes, this ratio always comes out to the same number.
Weight
Density x Speed x Speed x Diameter x Diameter
Don’t worry, it’s just a FRACTION!!!
Density x Speed2 x Diameter2= CWeight
Density x Speed2 x Diameter2C =
Do a wind tunnel test to find out what “C” is for the parachute
Weight
All “known” in the wind tunnel!
PITOT TUBE
In a pitot tube a probe consisting of two parts senses two pressures: impact (dynamic) and static.
The impact pressure is sensed by one impact tube bent toward the flow (dynamic head).
The static pressure is sensed through a small hole on the side (static head).
They develop low differential pressure and like all head meters they use a differential pressure transmitter to convert the flow to an electrical transmission signal.
Computers can also be used to solve problems in aerodynamics.
The computer solves complex mathematical equations that are based on Newton’s laws of motion
The wing or “airfoil” is a classic problem…