Shape and 2D Lift Relationship

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In summary, the conversation discusses the complexity of calculating lift coefficients and the challenges of applying them to overall wing design. The speaker, who is a community college graduate and RC aircraft hobbyist, is curious about a simpler way to calculate lift coefficients using 2D equations such as the NACA equations. However, the other person in the conversation explains that even with advanced technologies like wind tunnels and CFD calculations, accurately determining lift coefficients remains a complicated process. Flight tests are often necessary to ensure the calculations are correct before proceeding with the design process.
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How does the geometric shape of an airfoil effect 2D lift coefficient?
I’m aware that this is a simple question to a very complex question. However, I’m curious as to how to calculate a lift coefficient simply using a 2 dimensional equation or a series of 2 dimensional equations, such as the NACA equations. I’m somewhat familiar with the lift line theory, but to be honest it seems very complex and I am not aware of a simple and practical way to apply it. By this I mean; I would like to take the NACA or 2D airfoil equations and plug them into another set of equations to arrive at a usable result for overall wing design. I apologize for any ignorance on my part; I’m a community college graduate who enjoys designing RC aircraft as a hobby, so I have not taken any aerodynamics classes or training. Thanks for any assistance.
 
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Sorry, it doesn't get simpler-- it gets more complicated. In fact, that is why the wind tunnels are still so busy. Even the Navier-Stokes Computational Fluid Dynamics (CFD) calculations that supercomputer use are not completely reliable. The flight tests of a newly designed airplane are done in cautious steps to check that the aerodynamics calculations look ok to proceed to the next test step.
 
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FactChecker said:
Sorry, it doesn't get simpler-- it gets more complicated. In fact, that is why the wind tunnels are still so busy. Even the Navier-Stokes Computational Fluid Dynamics (CFD) calculations that supercomputer use are not completely reliable. The flight tests of a newly designed airplane are done in cautious steps to check that the aerodynamics calculations look ok to proceed to the next test step.
Keeps food on my table. 🤣
 
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That sounds interesting, AN EQUATION FOR LIFT!!

But its not that simple, even slight modification in airfoil shape changes its aerodynamics significantly, ultimately deciding its application.
For example, NACA C4 series are used in subsonic compressor blades because they are thick and provide good pressure disrribution. Whereas, DCA (Double Circular Airfoil) are used in transonic rotors because they are thin.
So changing shape of airfoil changes lots of things, a simple equation might not able to caplture all this.

Maybe a machine learning model with lots of data for various airfoils at different mach no. and AOA can be little help here.
 

FAQ: Shape and 2D Lift Relationship

What is the relationship between shape and lift in 2D airfoils?

The relationship between shape and lift in 2D airfoils is primarily governed by the airfoil's geometry, which affects the airflow around it. Different shapes can create varying pressure distributions above and below the airfoil, influencing the lift generated. For instance, cambered airfoils typically produce more lift than symmetrical airfoils at the same angle of attack due to the difference in airflow speed and pressure created by their curvature.

How does angle of attack influence lift for different shapes?

The angle of attack is the angle between the chord line of the airfoil and the oncoming airflow. As the angle of attack increases, lift generally increases up to a certain point, known as the stall angle. Different shapes react differently to changes in angle of attack; for example, a highly cambered airfoil may achieve maximum lift at a lower angle of attack compared to a flatter airfoil. Beyond the stall angle, lift rapidly decreases, leading to a loss of control.

Why do some shapes produce more lift than others?

Some shapes produce more lift than others due to their ability to manipulate airflow and pressure distribution effectively. Shapes with a greater curvature or camber can create a larger pressure difference between the upper and lower surfaces, resulting in increased lift. Additionally, features like leading-edge modifications and winglets can enhance lift by improving airflow attachment and reducing drag.

What role does viscosity play in the lift generated by different shapes?

Viscosity affects the lift generated by different shapes by influencing the boundary layer of airflow over the airfoil. A thicker boundary layer can lead to flow separation, which reduces lift. Shapes that promote smoother airflow and delayed separation, such as those with a gradual curvature, tend to perform better in terms of lift generation. Additionally, at higher Reynolds numbers, the effects of viscosity become less pronounced, allowing for more efficient lift generation.

How can computational fluid dynamics (CFD) help in understanding the shape-lift relationship?

Computational fluid dynamics (CFD) can provide detailed insights into the shape-lift relationship by simulating airflow around various airfoil geometries. CFD allows scientists and engineers to visualize pressure distributions, flow patterns, and the effects of different shapes on lift generation under various conditions. This analysis helps in optimizing airfoil designs for specific performance criteria, leading to improved efficiency and effectiveness in applications like aviation and wind energy.

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