An Overview to Aerodynamics

When the moving air flows around the solid body, i.e., an Aircraft, a detailed study into the aerodynamic forces such as lift, drag, side forces, and moments caused by these flow forces is what we know as "The Dynamic Segment Aerospace, Aerodynamics."

This subject offers insights into various theories, concepts, physical significances, derivations, etc. But one thing that really engages a person's interest in Aerodynamics is how the various complex discoveries of science are explained beautifully yet simply.

So, let's get to know about the subject and understand how it works. In this study, I will talk about the top 3 matters of AD, each of which has a distinct mechanism of approach to applications in the domain of Aerospace and owns fantastic properties.

1. The role of Angle of Attack in determining the lift value in an airfoil

2. The Kutta Joukoueski Theorem

3. Finite Wing Theory

The Role of Angle of Attack in determining the lift value in an airfoil

The angle of attack affects the lift value in an airfoil in the following ways:-

Case 1:- Angle of Attack before the stall

Before the occurrence of the stall point, with the increase of the angle of attack, the lift increase and attains the maximum value.

So, when the angle of attack increases, therefore, the value of (PL - PU) will increase because PL is increasing and PU is decreasing or remaining constant, as a result of which the difference between the two will be positive and increasing. So if the pressure difference is positive, the lift generated too will be positive.

The positive lift is taking place only because of the alignment of the angle of attack, which enables the Airfoil to have a pressure difference whose net effect would be positive.

Case 2:- Angle of Attack After Stall

After the occurrence of the stall point, with the decrease of the angle of attack, the lift starts decreasing.

So, when the angle of attack decreases, the value of (PL - PU) will decrease because PL is decreasing or remaining constant, as a result of which the difference between the two will be negative. So if the pressure difference is negative, the lift generated too will be negative.

The negative lift is taking place only because of the alignment of the angle of attack, enabling the Airfoil to have a pressure difference whose net effect would be negative.

Application:- 1. From above, it is evident the angle of the angle is more like a guide that assists an individual in determining the value of lift of an airfoil. Besides this, the critical angle of attack acts as an indication of the stall, which the pilot needs to know.

2. Also, with the increasing of the Angle of Attack, there is the presence of an "Increased Aerodynamic Loading," which further condenses the stall sequence and the progression from indication to buffeting.

3. AOA Indicator is a device that works its way to get the pilot's attention (via audio and/or low-cost stick shakers). This focuses the pilot's attention on where it needs to be to avoid the stall. It can also help when used in conjunction with airspeed and existing stall warning systems, when available.

The Kutta Joukoueski Theorem

It states the beautiful relation of lift generation per unit span with that of free stream density, free stream velocity of the fluid, and circulation around the Airfoil. In simpler words, the theorem states that the lift per unit span is directly proportional to the circulation around the body.

Applications:- 1. This theorem intensifies our understanding of lift generation. It describes how the lift generation is something much beyond just written definitions, terms, and analytical diagrams. It is the mechanism that allows humankind to create faster, efficient, commercially viable, and intricate lift-producing Aircraft.

2. In a world where the advancement of automation is taking a swift turn with superfast computers, and the computational or derived mathematical estimates holds no value, comes the Kutta Joukowski Theorem, which still has a firm grip on science (i.e., in Aerospace) with its instructive approach and marks the foundation for students of aerodynamics.

Finite Wing Theory

A section of the wing is Airfoil. So the Airfoil is considered in the infinite wing. But in the finite wing, the cross-section across the wing or the Airfoil is considered. So now, one may ask the fundamental distinction between that of an infinite wing and a finite wing.

The basic distinction between the two is that Edge Effects/Tips/Wingtips exist in Finite wings, which is not present in Infinite Wings.

About the theory-

The prime reason for the generation of lift is a finite value of a pressure difference below and above the Airfoil surface. So, as the byproduct of this pressure imbalance/difference, the flow near will curl back from the lower surface to the upper surface across the tips or edges of the wings and will further move inward. After the curling, the flow tends to leak from the lower to upper surface across the edge tip or around the wingtips. This will result in the formation of Tip Vortices.

Tip Vortices are a trailing vortex created at each wingtip. The pressure difference across the Tip Vortices is huge. The vortices are essentially weak tornadoes that trail downstream of the finite wing.

The tip Vortices pull or drag the fluid around it in a downward direction. As a result, a downward component of velocity is experienced, known as Downwash. The effect caused by this phenomenon is known as the Downwash Effect.

Applications:- This theory provides a thorough perception of finite wings, Lift generation, the distinction of finite and infinite wings, Tip Vortices, Downwah, and the effective interconnection between all the parameters.

Conclusion

The above discussed three concepts were some of the critical features of Aerodynamics. This subject as a whole incorporates a massive deal of applications in the Aircraft, launching of vehicles and missiles, spacecraft design, helicopters, and even in data center cooling, human physiology, and study of birds and fishes.

In Aircraft, the study of AD works for subsonic, trans-sonic, and supersonic wing design, spoilers, tailplane, Nose cone, landing gear, etc. Passenger cabin design (to simulate optimum airflow for passenger comfort). The implementation of Noise Reduction techniques such as the Chevrons in the Boeing 787 dream liner engines. The Chevrons work towards reducing the engine noise by facilitating bypass air mixture with the ambient air stream.

I believe there is nothing much to cover about the subject as I have comprehensively discussed everything relevant. Thus I hope this report will help an individual to have the intrigue towards AD.

Also, I am hoping that this report will resolve all your queries regarding the same.