Multi Element Airfoils, Laminar and Turbulent Flow on Airfoils; Airfoil Trailing Edge Noise — Lesson 7

This lesson covers the aerodynamics of airfoils, focusing on multi-element airfoils, laminar and turbulent flow past airfoils, and airfoil trailing edge noise. It delves into the effects of flap deflection on lift coefficient, the implications of positive and negative deflections, and the influence of leading edge flap on lift coefficient. The lesson also discusses the behavior of airfoil sections when applied on an aircraft, the deployment of multi-element configurations, and the impact of skin friction. An illustrative example is provided to demonstrate the difference in the coefficient of friction considering a completely laminar boundary layer and a completely turbulent boundary layer.

Video Highlights

02:16 - Explanation of the influence of leading edge flap on lift coefficient.
07:53 - Explanation of the difference between streamlined bodies and bluff bodies.
10:16 - Discussion on the impact of skin friction coefficient.
16:12 - Discussion on the aerodynamics of bluff bodies.
27:15 - Explanation of the concept of aero acoustics and flow-induced noise.

Key Takeaways

- Multi-element airfoils are designed to increase the effective angle through which the flow is turned, thereby augmenting lift and reducing stalling velocity.
- The deployment of leading edge flap improves the maximum lift coefficient without major shift of the lift coefficient versus angle of attack curve.
- The boundary layer thickness for a laminar flow is smaller than that for a turbulent flow, resulting in a larger skin friction for the latter.
- Trailing edge noise, a key element that annoys human beings, can be suppressed using various noise reduction devices.