Wind tunnels are types of equipment used in aerodynamic research to explore the effects moving air past solid objects. Wind tunnels consist of tabular passages with the solid object under test mounted in the tubular middle region. A powerful fan system or other means forces the air to move past the object. Suitable sensors are fitted on a wind tunnel model that is the test object to measure and estimate pressure distribution, aerodynamic forces and other aerodynamic-related traits.
The earliest wind tunnels invention was towards the end of 19th century, in the aeronautic research early days, when many countries, organisations and individuals attempted to develop successful machines that were heavier than air. Wind tunnels were envisioned as a way of reversing the usual paradigm; instead of an object moving through still standing air, the same effect would be achieved if the air moved at speed past a still standing object. In that sense, an observer who is stationary could study and explore the flying object in action and could measure and estimate the aerodynamic forces acting on the stationary object.
The development of wind tunnels led to the airplane's development. Enormous wind tunnels were developed during the Second World War. Wind tunnels testing were perceived of crucial importance in the development of supersonic missiles and aircraft during the period of Cold War.
The study of wind tunnels came into its own after the rising need to study the effects of wind on large and tall man-made objects and structures that offered large surfaces for the forces of wind to act upon and how to resist the wind forces by the use of buildings’ internal structures. Estimating and determining these forces a requirement before the specification of the necessary strength of such structures by building code and such tests continued to be employed for unusual or large buildings. Later, wind tunnel testing was applied to automobiles to establish means to required power to move the vehicle at a given speed on roadways.
NASA primarily uses wind tunnels to test rockets and spacecrafts. These vehicles are designed to operate in the space. Rockets and spacecrafts have to travel via the atmosphere to get to space. Also, vehicles that serve to take people into the space must come back via the atmosphere to Earth. Wind tunnels are very crucial in making the new Orion spacecrafts and Ares rockets. Engineers from NASA mostly employed wind tunnels in testing Ares’ design ideas and Orion models. They used the wind tunnels to determine what would happen to different models of spacecrafts if they travelled through the atmosphere.