Aerospace Engineering

Wind Tunnel Testing

Wind tunnels are giant tubes with air rushing through them that are used to simulate the interaction of air with an object that is flying through the air or moving along the ground. Wind tunnels are used by aerodynamicists to test models of prospective aircraft and engine components. The model is put in the test part of the tunnel and air is forced past it during the test. The forces on the model are measured using a variety of instruments. NASA uses wind tunnels to evaluate ideas for improving and securing airplanes. Engineers can put innovative materials or shapes for plane parts to the test. Then, before flying a new plane, NASA will put it through a wind tunnel test to ensure that it will fly properly. The air in a wind tunnel is normally moved through the tube by strong fans. The thing to be tested is placed in the tunnel in such a way that it cannot move. The air moving around the static object represents what would happen if the object were in motion. The settling chamber, the contraction cone, the test bed, the diffuser, and the fan housing with a variable speed motor are the five essential components of the wind tunnel, ordered from front to back. In order to provide very accurate results in drag measurement, transonic wind tunnel testing must produce results within 1 count (1 count = around 0.3 percent of total resistance, which is comparable to 1–2 seats). Wind tunnels are built with a certain function in mind and for a specified speed range. A series of spinning vanes convey air from the exit of the test section back to the fan in the closed return tunnel. The air is returned to the contraction portion and back via the test section after exiting the fan. The model is instrumented in certain wind tunnel tests to offer diagnostic information about the flow of air around the model. Static pressure taps, tufts on the surface, and total pressure rakes are examples of model instrumentation. Models of wind tunnels are complicated and expensive pieces of machinery. Wind tunnels are commonly used in aerodynamic research to study the behavior of flows in channels and across solid surfaces under various conditions. Aerodynamicists can utilize the wind tunnel's controlled environment to measure flow conditions and forces on aircraft models as they are being developed. Low-speed and high-speed wind tunnels are divided into subsonic (80 percent of the speed of sound), transonic (about the speed of sound), supersonic (up to 6 times the speed of sound), hypersonic (6 to 12 times the speed of sound), and hypervelocity (up to 12 times the speed of sound).