Aerodynamics

Aerodynamics is the fundamental enabling science that underpins the aerospace industry. Without the ability to generate lift from airflow passing over aircraft wings, helicopter rotor blades, and jet engine turbine blades, it would not have been possible to fly the sophisticated heavier-than-air vehicles and design future flight vehicles.

Much of the development of current highly efficient aircraft has been due to the ability to model aerodynamic flows accurately and thus to design high-performance wings.

It is thus required to understand the underlying mathematical aerodynamic model and the computational technique to analyze the flight vehicle.

Aerodynamic theories navigate through exciting territories, starting from fundamental concepts of potential flows and increasing complex concepts of the boundary layers and the Navier-Stokes equations. Computational aerodynamics deals with subjects of incompressible and compressible flow around airfoils/wings across the entire speed range, applications related to drag reduction, low Reynolds number aerodynamics, high lift devices, and flow control.

Going back in chapters of history …

Aerodynamics has been developed over many centuries and has grown steadily as a fundamental extraordinary science, with underlying concepts lying in fluid mechanics. One of the initial goals of the Aeronautical Society of Great Britain, formed in 1866, was to develop the methods to estimate the lift and drag on a flat plate. George Cayley further laid the foundation of flight in the 19th century, where he introduced concepts of wing shapes, flight stability. The pioneering works in modeling fluid flow were established by Euler, Navier, Saint Venant, and Stokes by 1850.

However, a search was on to further simplify these models. This has resulted in the concept of velocity potential by Lagrange and its practical utility was demonstrated by Helmholtz through vortex theorems. This approach was followed over a decade with insights into conformal mapping, thin airfoil theory, finite wing theory for potential flows, which forms the bedrock of intuitive concepts of aerodynamics.

The parallel development of boundary layer theory to embed viscous effects formed the bridge between ideal and real fluid flow as an aid in the analysis and design of aircraft for steady-state operation by focusing on the lifting surface behavior.

One of the major grey areas was in the area of viscous flows and in understanding transition and turbulence, without which accurate prediction of drag is not possible. Modern methods of DNS, solving equations of Navier-Stokes from first principles, without any models helped in solving the last barrier.

 

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