SURFACE PRESSURE MEASUREMENTS AT THE TIP OF A MODEL HELICOPTER ROTOR IN HOVER

Detailed blade-tip surface pressure distribution data for a single-bladed model helicopter rotor in hover are presented. The pressure measurements were made along the chordwise direction at six spanwise stations out-board of the 94 percent radial location on the rotor blade. Data were taken at blade collective pitch angles of 0, 6.2, and 11.4 deg. The points of inception of the primary vortex inferred from the pressure data agree with those noted by other investigators using surface flow visualization techniques. The presence of both a primary and a secondary vortex near the rotor tip at a pitch angle of 11.4 deg is observed. Normal and chordwise force coefficients obtained by integrating the pressure data are also presented.

[1]  John B. Wheatley.  An aerodynamic analysis of the autogiro rotor with a comparison between calculated and experimental results , 1935 .

[2]  Anton J. Landgrebe,et al.  An Analytical and Experimental Investigation of Helicopter Rotor Hover Performance and Wake Geometry Characteristics , 1971 .

[3]  Blade Tip Aerodynamics-Profile And Planform Effects , 1968 .

[4]  P. Raj,et al.  Computation of Three-Dimensional Potential Flow Using Surface Vorticity Distribution , 1979 .

[5]  H Sternfeld,et al.  TIP VORTEX CORE THICKENING FOR APPLICATION TO HELICOPTER ROTOR NOISE REDUCTION , 1966 .

[6]  S. J. Shamroth,et al.  A viscous flow analysis of the tip vortex generation process , 1979 .

[7]  J. C. Balcerak,et al.  The Nemesis of the Trailed Tip Vortex--Is It Now Conquered? , 1972 .

[8]  Barnes W. McCormick,et al.  A study of rotor blade-vortex interaction , 1970 .

[9]  James L. Tangler,et al.  A Prescribed Wake Lifting Surface Hover Performance Analysis , 1977 .

[10]  Pradeep Raj,et al.  A method of computing the potential flow on thick wing tips , 1976 .

[11]  I. H. Abbott,et al.  Theory of Wing Sections , 1959 .

[12]  N. A. Chigier,et al.  Tip vortices: Velocity distributions , 1971 .

[13]  Koodige Rajarma Shenoy.  A method of computing the pressure distribution on a single-bladed hovering helicopter rotor , 1979 .

[14]  Eastman N. Jacobs,et al.  Airfoil section characteristics as affected by variations of the Reynolds number , 1939 .

[15]  Montgomery Knight,et al.  Pressure distribution over a rectangular monoplane wing model up to 90 degree angle of attack , 1929 .

[16]  Ira H. Abbott,et al.  Summary of Airfoil Data , 1945 .

[17]  Vortex flow over helicopter rotor tips , 1971 .

[18]  R. Gray.  AN AERODYNAMIC ANALYSIS OF A SINGLEBLADED ROTOR IN HOVERING AND LOW- SPEED FORWARD FLIGHT AS DETERMINED FROM SMOKE STUDIES OF THE VORTICITY DISTRIBUTION IN THE WAKE , 1956 .