CFD Simulation of Steady, Compressible Flow around the Naca 2412 Airfoil

Abstract

Purpose: The study of fluids is key for understanding the world around us. Today, aircrafts are ubiquitous for transportation of goods and personnel. The key forces at play during aircraft propulsion; lift and drag, are affected by the shape and positioning of the airfoils around the aircraft. Understanding of the flow dynamics around the airfoil in an aircraft is vital to optimizing its design.

Methodology: In this study, analysis of the NACA 2412 airfoil is carried out using ANSYS Fluent. A 2D model of the airfoil in a rectangular flow domain is developed, with air as the working fluid. The viscous-inviscid fluid model is assumed. Pressure-based solver type is adopted, with absolute velocity formulation and steady time. The pressure, density, velocity and Mach number behaviours at two different velocities and angles of attack respectively are then analysed.

Findings: At velocity magnitude of 285 m/s, there is a gradual change in fluid properties (pressure and density) after the leading edge, and a sharp change in the fluid properties towards the trailing edge of the airfoil. The former signifies the formation of expansion waves while the latter signifies the formation of shock waves. The flow after the stagnation point also moves gradually from subsonic to supersonic upstream of the shock wave, and abruptly to subsonic after the shock wave. This indicates that as freestream velocity approaches the speed of sound, there is increased tendency for the formation of expansion and shock waves. The nature and location of the waves depend on the angle of attack of the airfoil.

Unique Contribution to Theory, Practice and Policy: The analysis results provide significant insights into the aerodynamic behaviour of airfoils under different flight conditions, providing a more cost-effective solution for aircraft design optimization, compared to using models in wind tunnels at the early design stages.