Accession Number : ADA309509

Title :   Aerodynamic Characteristics of Rotor Airfoils as Affected by Simulated Ballistic Damage.

Descriptive Note : Master's thesis,

Corporate Author : MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING

Personal Author(s) : Robinson, Keith W.

PDF Url : ADA309509

Report Date : 1995

Pagination or Media Count : 178

Abstract : Tests were made using a 2-D insert in a subsonic wind tunnel to examine the effects of simulated ballistic damage on the aerodynamic characteristics of ten helicopter rotor blade sections. Two undamaged baseline blade sections, comprised of SC1095 and SC1095R8 airfoils, were tested and then modified with different simulated ballistic damage configurations. These comprised of a circular hole with the surrounding skin removed, fore and aft circular holes, and an aft wedge-shaped hole. One blade section was subjected to actual ballistic damage near the trailing edge. The sectional lift, drag and pitching moment were measured at positive and negative angles of attack at Reynolds numbers of one, two, and three million. Pressure measurements were also made for two configurations fitted with pressure taps. Additional tests were conducted over a full 360 degree range in angle of attack for a Reynolds number of one million. The measurements were complemented by oil flow visualization on the blade sections. The simulated damage caused large disturbances in the flowfield near and downwind of the damaged regions. Generally, flow separation was initiated at the upstream leading edge of the damage, followed by a growth in separation, both in span and intensity, with increasing angle of attack. The aerodynamic characteristics were significantly degraded, with up to a 60 percent reduction in lift-curve-slope, a loss of maximum lift capability of nearly 30 percent, and a significant decrease in the lift-to-drag ratio due to drag increases of up to nearly 340 percent at low angles of attack.

Descriptors :   *HELICOPTER ROTORS, *ROTOR BLADES(ROTARY WINGS), *TERMINAL BALLISTICS, *AERODYNAMIC LIFT, AERODYNAMIC CONFIGURATIONS, ATTACK HELICOPTERS, PITCH(MOTION), AERODYNAMIC STABILITY, DAMAGE ASSESSMENT, VULNERABILITY, THESES, VORTICES, COMPUTATIONAL FLUID DYNAMICS, ANGLE OF ATTACK, FLOW VISUALIZATION, PRESSURE MEASUREMENT, AEROELASTICITY, FLOW FIELDS, HOLES(OPENINGS), AERODYNAMIC LOADING, WIND TUNNEL TESTS, AERODYNAMIC DRAG, SUBSONIC CHARACTERISTICS, LEADING EDGES, TWO DIMENSIONAL FLOW, FLOW SEPARATION, SKIN(STRUCTURAL), PRESSURE DISTRIBUTION, REYNOLDS NUMBER, SUBSONIC WIND TUNNELS, TRAILING EDGES, LIFT TO DRAG RATIO.

Subject Categories : Aerodynamics
      Helicopters
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE