Aerodynamic Characteristics of Rotor Airfoils as Affected by Simulated Ballistic Damage.
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1995
- Accession Number
- ADA309509
Entities
People
- Keith W. Robinson
Organizations
- University of Maryland