Author(s)

S. Djellal, T. Azzam, M. Djellab & K. Lakkaichi

Abstract

The flow around a NACA 641-412 airfoil with circle damage is numerically investigated using the Ansys Fluent package. Several diameter values are considered for the damage which is located at either quarter or mid chord. The numerical domain is covered with a multiblock structured hexagonal grid consisting of 344,680 cells in the undamaged case and 351,540 cells in the damaged case. Inside the damage hole, a structured tetragonal mesh is used. Turbulence effects are taken into account via the k- model. The results show that the presence of the damage hole decreases the lift coefficient and increases the drag coefficient, resulting in a loss of airfoil performance (fineness decrease). The numerical simulations show that the flow through the damage corresponds either to a weak or a strong jet. In the first case an attached wake forms giving the smallest change in the force coefficients whereas the second case shows a separated wake with a reverse flow giving the highest force coefficient change. The present paper also compares the structure of the damage through flow with previously published experimental results. Finally, the numerical solution is qualitatively and quantitatively validated using available experimental results. Keywords: damage, drag, lift, strong jet, weak jet, undamaged. 1 Introduction The survivability of an aircraft is becoming one of the key aircraft design requirements [1] and is dependant upon its vulnerability to damage caused by a variety of threats. Published works to date in this field focus mainly on twodimensional wings.

Keywords

damage, drag, lift, strong jet, weak jet, undamaged.