Aerodynamics is the core of aeronautical engineering which deals with the study of air flow over a body and the behaviour of flow characteristics over the body. This has been a very interesting subject for many people from various fields proving to be one of the most important for their respective profession.
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| aerodynamics used in cars |
The god of cricket Sachin Ramesh Tendulkar had attended crash courses on aerodynamics and flow over a ball just to understand how a cricket ball spins and learn to use it to his advantage. there have been similar other sportsmen who have learnt aerodynamics in sports such as golf, football and hockey and a wide variety of engineers who have been trying to make the most out of this wonderful subject. since our blogs are related to aeronautical engineering lets try understanding how well aerodynamics is applicable in the flying of of the huge beautiful metallic birds.
The aerodynamics or flow of air over an aircraft is generally divided into two main fields of study. Namely; subsonic aerodynamics and supersonic aerodynamics. The subsonic aerodynamics as the name suggests deals with the study of flow of air over an aircraft when the aircraft is flying at speeds lesser than mach 1 or less than the speed of sound. In this type of flow the air is considered to be inviscid, i.e. non viscous, and incompressible. Though air is practically a compressible fluid its compressibility effects do not show up much
in the subsonic regime only when the speed of flow reaches a value close to mach 1, i.e. around mach 0.8, the compressibility effects of air becomes significant and is taken into considerations for studies. On the other hand supersonic aircraft deals with flights involving speeds greater than mach 1 which also includes hypersonic flights (speed greater than mach 5).Supersonic aerodynamics aircraft takes into the consideration the compressibility effects as well as the viscous effects of the flow and the affects of these effects at such high velocities is what makes the base for supersonic aerodynamics. As soon as a flow gets changed into a supersonic from a subsonic flow it gives rise to what is known as shock waves
which generate a sudden and steep change in the drag induced. This is caused due to travelling of the aircraft at the speed of sound. Since the source of the sound generation travels at the speed of sound, sound waves ( which is nothing but a pressure disturbance itself) accumulate together with the aircraft giving rise to a very high and unnecessary drag. Due to this the aircraft's generally prefer travelling at speeds which are far from the speed of sound (either high supersonic or high subsonic). This region where the drag increases drastically is called as the transonic region in aerodynamics. We will deal with supersonic and subsonic flow phenomenons in our future posts.
Now that we know there are two flow type studies in aerodynamics we should also understand that both these types of flows can be generated in a laboratory by the help of experimental setup.
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| fig. a subsonic wind tunnel schematic |
Such setups used to study the flow of air over a given body is called as a WIND TUNNEL. There are both subsonic as well as supersonic types of wind tunnels which are being used actively to study the slow of air over aerofoils and air crafts.
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| fig. a schematic of blow down supersonic wind tunnel |
While subsonic wind tunnels are all continuous and run for a long duration of time, their supersonic counter parts run for a significantly lesser time lasting only up to a few seconds to a few minutes. But supersonic wind tunnels are used only in large research centres and universities where research is being carried out on supersonic flight. Do get back in future to read more on wind tunnels and their working in our future posts.
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| a subsonic wind tunnel |
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| a supersonic wind tunnel |
This was our post on aerodynamics-an introduction, hope you liked it. Add us on +1 and follow us to keep getting updated on our posts and blogs in future.
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