Aerofoils - How Wings Work - Assignment Example

Name: Tutor: Date: Course: Aerofoil: How Wings Work 1. Common Misconceptions about Lifts One of the common misconceptions about lifts is the concepts of lateral flow or span-wise flow. It is common misconception that the wingtip vortices are associated with the unnecessary span-wise flow. It is sometime believed that lifts and trailing vortices are associated with the flow of air around the pan. This is however a misconception as the lifts and trailing vortices are not associated with the lateral flow. Another misconception regards the velocity relative to the skin of the wing. The misconception is that the lift is usually produced by the velocity relative to the wing of the skin. This is because the air has a velocity and pressure everywhere and it is not just concentrated at the surface of the wings (Kemp, 10). Air has a defined velocity everywhere and it is not just at the contact point with the wings. The Magnus effects and the Bernoulli’s principles are applicable in terms of creating the circulation that is needed for the purposes of carrying out a mechanical lift. The third misconception about lifts is about the wings. The misconception is that the wings must be curved at the top and flat at the bottom for the purposes of supporting the lift. This is however not true as the pilots may sometimes fly their planes upside down for a long period of time. Had the idea been true, it would have been impossible to fly the planes upside-down. The shape of the wing influences the air circulation as it forms the first point of contact with the air. It is thus important to note that the airfoils do not produce lift due to their curved nature at the top. 2. How an aerofoil generates Lift The angle of attack as well as the shape of the aerofoil is important in terms of generating a lift. When the airfoil is places at the correct angle, it deflects the incoming air and hence creating a force. The force is however in the direction opposite to the deflection. This force is usually referred to as an aerodynamic force. The sum of the obstacle effect is important in terms of generating flow pattern at the wings. It is also important to note that it is not possible for the airfoils to generate a lift at zero angle of attack. Although the curvature of the airfoil is important, it does not affect the generation of the lift. Creation of higher pressure on one side and lower pressure on the other side is also achieved through the turning of the air which creates curved streamlines (Wood 61). The creation of a pressure difference plays an important role in terms of creating a velocity difference. This is achieved through the Bernoulli’s principles. According to the principle, air has a high velocity when the pressure is low. The wings play an important role during the process in terms of changing the airspeed. The flow field that is created leads to a higher velocity on the upper side and low velocity in the lower surface. The Kutta condition plays an important role in terms of dealing with the flow of air and the circulation of the air. This can also be explained by Newton’s law of motion with regards to the action and reaction. The process thus results to the generation of a lift. The amount of lift that is generated is equal to the circulation, times density, times wingspan and times airspeed. 3. Why an aerofoil shaped as it is The shape of the aerofoil is rounded for the purposes of creating streamlines with higher turning. This plays an important role in terms of creating a greater lift. The shape of the aerofoil is for the purposes of withstanding higher velocity and lower static pressure on the upper surface. This is also considering that the aerofoil provides a point of contact with the air which in turn influences the circulation of the air. On the other hand, the shape at the rear is also for the purposes of withstanding the high static pressure that is usually generated and is responsible for the lift. The shape is also important in terms of creating a lift. The shape is also important in terms of creating a flow pattern of the air during the lift and hence ensuring that the circulation is as required (Ross, 57). The shape is also important in terms of creating a pressure pattern that is useful in terms of creating the lift. The shape of the wing also plays an important role in terms of maintain the balance of the aircraft. However, it is important to note that apart from the shape other factors aid s in the creation of a lift. This is because the planes can still use different shapes of aerofoil to fly. The shape also plays an important role in terms of creating streamers and hence improving on the circulation process. The camber is also important in terms of influencing the shape of the aerofoil. This also influences the size of the aerofoil. It is thus important to note that the shape of the aerofoil plays an important role in terms of creating the lift although it does not have a major role. In terms of cost, the shape is guided by the camber as it may be more costly for the manufacturers to come up with some shapes. Shapes that will generate a lift The generation of a lift is dependent on how much flow is turned (National Aeronautics and Space Administration, 3). This is therefore means that the shape of an object plays an important role in terms of generating a lift. On the other hand, this means that the greater the flow turning, the greater the lift. A brick house will not generate a lift. This is because it will not turn much flow which is required to produce a lift. The streamlines of a brick house does not create any turning and hence impacting negatively on the lift. This indicates that the streamlines also determines the amount of turning which is also responsible for generation of a lift. A saucer can generate some amount of lift when it is inverted. This is because it has a curvature and a camber that will impact positively on the turning and hence resulting to the generation of a lift. A football ball on the other hand will generate a lift although the stability will be impacted negatively. This is because it has the ability of producing a greater turning which leads to the generation of a lift. However due to the pressure differences, it will impact negatively on the stability and hence making it difficult to control it. The round shapes have the potential of creating a curvature although the shape has a great influence on the ability of the object to generate a lift. Shapes with no camber cannot generate a lift and the reason as to why the aerofoil is not flat. Varying the amount of lift is also important in terms of controlling the aircraft and it is dependent on the shape. In some instances, brute force is required during the generation of a lift. This is in some way related to the shape of the aerofoil. Considerations should thus be placed on the camber for the purposes of coming up with an appropriate shape. The consumption of fuel may also be high when brute force is used and hence a disadvantage. Shapes that cannot generate a lift Shapes That Can Generate a Lift What causes Drag and what the different types of Drag A drag is an air resistance which is caused by forces acting opposite to the motion of the substance moving in the fluid. The creation of a lift is also associated with a drag and it is composed of two primary components which includes a vortex and an inducement of a lift. The air resistance and an air lift is responsible for a drag in term of the aerobics. Air resistance is as a result of the generation of a force that acts in the opposite direction and hence causing the resistance. The lift induced drag and the parasitic drag are the two main types of drags. The creation of a lift on the wings of an aircraft results to a lift induced drag. The lift induced drag increases with an increase in the lift on the body. According to Chung, (26), a parasitic drag is caused by the movement of a solid object within a fluid. The roughness of the surface also plays an important role in terms of influencing the parasitic drag. It is for this reason that the aerofoil always has a smooth surface for the purposes of dealing with the parasitic drag and the air resistance. The increase in speed also leads to an increase in the parasitic drag. The efficiency of the aircraft is dependent on the parasitic drag which is also important in terms of the regulation of speed. The parasitic drag also plays a role in the regulation of the fuel consumption by pilots during a flight. A power curve can be obtained through the analysis of the induced drag and the parasitic drag. This is important to the pilot as it provides information with regards to the airspeed. It influences the fuel consumption which is also important for the purposes of moving the aircraft. The parasitic drag and the induced drag are important in terms of determining the speed that the pilots may use at different times. Boundary Layer The boundary layer is part of the flow where the force of viscosity surrounds the part with non viscous flow. The area between the viscous flow area and the non viscous flow area is considered as the boundary layer. The equation of the fluid flow is important in terms of dealing with the issues of boundary layer in aerodynamics. The fluid flow areas are divided into two sections. One section is where viscosity dominates and the drag effect is also felt. The other area does not experience viscosity and its impact is minimal and it can be neglected. The pressure distribution in the boundary layer normal to the aerofoil is usually constant and the heat transfer also takes place. The boundary layer transition also plays a role in terms of creating turbulence which affects the movement of the aircrafts. The shape of the aerofoil plays an important role in this case in terms of dealing with the issues of turbulence (Emmons, 18). Laminar flow is also associated with the boundary layer and it is related to velocity and Reynolds number. It is usually important to achieve a lower Reynolds number for the purpose of maintaining the laminar. It is also important to note that the laminar flow is usually achieved as a result of maintaining the same conditions. Low skin friction is usually achieved when the Reynolds number is low and hence impacting positively on the aerofoil. The boundary layer equations play an important role in terms of dealing with viscosity issues that are associated with the boundary layer (Schubauer, 14). The two important boundary layer equations include the Navier-stokes equation and partial differential equation. Reynolds decomposition is usually applied in terms of dealing with the turbulent boundary layer. The concepts of heat transfer and velocity also play an important role in terms of dealing with the concepts of the boundary layer. Wingtip vortices and what causes them Wingtip vortices are circular patterns of rotating air that are generated by the wings of an aircraft when it generates a lift. The wingtip vortices occur at points as opposed to the wings and hence the reason as to why it is sometimes referred to as lift induced vortices. The wingtip vortices are usually associated with the induced drag. The concept of wake turbulence is closely associated with the wingtip vortices. During the generation of the aerodynamic lift, the air on the top surface has a lower pressure as compared to the bottom surface (Beaty, 5). This causes the air to flow from below the top of the wing and in turn causing the flow of air in a circular fashion. It is also important to note that the wingtip vortices have several effects which could be negative. The angle of attack is reduced by the wingtip vortices which has a negative impact on the process of generating a lift. The wingtip vortices can also cause hazards and it is closely associated with the wake turbulence. The size of the aircraft and its speed plays an important role in terns of determining the wingtip vortices. The wingtip vortices from a large aircraft may persist for sometimes depending on its speed. This may impact negatively on the light aircrafts incase it is landing at the same point if the wingtip vortices will still be present. The air traffic controllers usually issue alerts to the pilots with regards to the wake turbulence that is caused by wingtip vortices which is important in terms of preventing accidents. What are the common formulas for L & D?   What do they depend on? The formulas for lift and drag are important in terms of designing the aerofoil. These formulas determine the shapes and the expected forces that need to be countered. The expected conditions or factors that influence the lift are considered in the formula. It is for this reason that the variables are included in the formula. On the other hand, it is also important to note that the formulas depend on other issues which are mainly the variables. The variables include the coefficient of drag (Cd) and the coefficient of lift (Cl). The coefficient of lift influences the amount of lift that can be generated. Other variables also includes; velocity (V), density, (r) and Area (A) (Rajakumar, 85). The area and density is also dependant on the size of the aircraft. The generation of lift must consider the size of the aircraft as different aircrafts have different requirements in terms of the lift. The most common formula for drag and drop include; Drag Drag=Cd*(r*V^2)/2*A Cd=Cd0+Cl^2/(pi*A*R*e) Lift Lift=Cl*(r*V^2)/2*A Cl=2*pi*AoA Graphs A zero angle of attack gives zero lift. This means that the lift cannot be generated when the angle of attack is zero. On the other hand, it is important to note that the maximum lift is generated by an angle of 20 degrees. The coefficient of lift at this point is i.5. It is thus important to note angle of attack plays an influential role in terms of determining the ability of a plane to generate a lift. Conclusion In conclusion, it is evident that the concepts of aerofoil have attracted different views. Some of the views are misconceptions that tend to explain the generation of lift. However, it is evident that the lift generation is dependent on various factors. The Bernoulli’s principles as well as the Newtonian laws of motion are involved in the generation of a lift. It is also evident that the shape of the aerofoil has some impacts of the generation of a lift. Streamlines are affected by the shape of the aerofoil which plays an important role in terms of lift generation. Forces, pressure and velocity are also important during the lift generation. Some shapes can generate a lift while other shapes cannot. However, it is important to note that a plane can fly upside down which is an indication that the shape may not be the main determining factor in terms of lift generation. Understanding the concepts of drag is also important in terms of dealing with the forces that are related to the lift generation. It is also evident that the concepts of boundary layer are important in terms of understanding the generation of a lift. The wingtip vortices are also an important concept that affects the generation of a lift. These phenomena may also impact negatively on the other airplanes landing or taking off in the same facility. The coefficients of lift and drag are also important in terms of calculating the maximum angle. The coefficients and the calculation of the lift and drag are important in terms of designing an aerofoil. It is also evident from the graph that angle zero cannot give any lift. Works Cited Beaty, William. Why does the smoke ring? Retrieved on 5 January 2014 from . 2012. National Aeronautics and Space Administration. Shape effect on lift. Retrieved on 5 January 2014 from 2014. Kemp, Nelson H. "On the lift and circulation of airfoils in some unsteady-flow problems." Journal of the Aeronautical Sciences (Institute of the Aeronautical Sciences) 19.10 (2012). Wood, David. "Aerofoils: Lift, Drag, and Circulation." Small Wind Turbines. Springer London, 2011. 57-75. Ross, Mark. "Modeling Unsteady Lift and Radiated Sound Generated by a 2-D Airfoil in an Intermittent Flow." Bulletin of the American Physical Society 57 (2012). Chung, Yongmann "Effectiveness of active flow control for turbulent skin friction drag reduction." Physics of Fluids 23.2 (2011): 025102. Schubauer, G. B. "Laminar boundary-layer oscillations and stability of laminar flow." Journal of the Aeronautical Sciences (Institute of the Aeronautical Sciences) 14.2 (2012). Emmons, Howard W. "The laminar-turbulent transition in a boundary layer-Part I." Journal of t he Aeronautical Sciences (Institute of the Aeronautical Sciences) 18.7 (2012). Rajakumar, S."Iterative approach for optimizing coefficient of power, coefficient of lift and drag of wind turbine rotor." Renewable Energy 38.1 (2012): 83-93. Read More