Experimental Investigation into the Aerodynamics of Battle Damaged Airfoils

Wind tunnel tests are reported that investigate three aspects of aerodynamic flows through battle damaged airfoils. The first aspect investigated was the effect of camber. This showed that reducing camber weakened the strength of the jet flow through the damage and delayed the onset of strong jet flows to higher incidences. The second investigation used five hole probe measurements to survey the flow field on a battle damaged flat plate airfoil. The measurements indicated that the use of the jet-to-freestream velocity ratio is a poor criteria for determining whether damage flows have undergone transition to strong jets. Finally, the influence of a star shaped hole to simulate more realistic battle damage was investigated. It was shown that in terms of damage flow characteristics and changes in lift, drag, and pitching moment coefficients, the use of a circular hole is a reasonable simulation of battle damage.