Wind Tunnels :: essays research papers

Wind Tunnels In this report I will talk about the wind tunnel. I will described what they are used for. The different types of wind tunnels from the slow speed subsonic to the high speed hypersonic tunnels. I will also give A few examples of the wind tunnels used today. The wind tunnel is a device used by many people, from High school students to NASA engineers. The wind tunnel is a device used to test planes to see how well it will do under certain conditions. The plane maybe as big as a full size 747 or as small as a match. To understand how a wind tunnel is used to help in the designing process you have to know how a wind tunnel works. How Wind Tunnels Work A wind tunnel is a machine used to fly aircraft's, missiles, engines, and rockets on the ground under pre-set conditions. With a wind tunnel you can chose the air speed, pressure, altitude and temperature to name a few things. A wind tunnel is usually has a tube like appearance with which wind is produced by a large fan to flow over what they are testing (plane, missiles, rockets, etc.)or a model of it. The object in the wind tunnel is fixed and placed in the test section of the tunnel and instruments are placed on the model to record the aerodynamic forces acting on the model. Types of Wind Tunnels There are four basic types of wind tunnels. Which are low subsonic, transonic, supersonic, and hypersonic. The wind tunnels are classified by the amount of speed they can produce. The subsonic has a speed lower then the speed of sound. The transonic has a speed which is about equal to the speed of sound (Mach 1 760 miles per hour at sea level). . The supersonic (Mach 2.75 to 4.96) has a speed of about five times the speed of sound And the fasts of them all the hypersonic (Mach39.5) which has a speed of more then 30,000 miles per hour. Wind Tunnel Test There are basically two types of wind tunnel test which are static stability and the pressure test. With these two test you can determine the aerodynamic characteristics of the aircraft. The static stability test the measures the forces moments due to the external characteristic. These forces include axial, side and normal force, rolling, pitching and yawing moment. This forces are found by using a strain gauge which is located on the external portion of the plane. It measures the external flow fields. Then the shadowgraph is used to show the shock waves and flow fields at a certain speed or angle of