Determination of Indicial Lift and Moment of a Two-Dimensional Pitching Airfoil at Subsonic Mach Numbers From Oscillatory Coefficients With Numerical Calculations for a Mach Number of 0.7
Abstract
The reciprocal equations relating the lift and moment acting on an airfoil due to harmonic oscillations in compressible flow to the indicial lift and moment functions for a pitching airfoil are determined. Two indicial functions are required to describe completely the lift or moment on the airfoil; one function is used for describing the effects due to the angular position of the airfoil whereas the second function is used for describing the effects due to pitching velocity. Calculations for the indicial lift and moment functions are made for a pitching airfoil at a Mach number of 0.7 for which sufficient oscillatory coefficients were available. The growth of lift to the steady-state value is less rapid for compressible flow than for incompressible flow for both indicial functions of the pitching airfoil. Although the circulatory lift due to pitching velocity on an airfoil rotating about its three-quarter-chord point is nonexistent at a Mach number of 0, for a Mach number of 0.7 a time-dependent lift exists because of pitching velocity and approaches zero in approximately 2 chords.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1952
- Accession Number
- ADA380673
Entities
People
- Bernard Mazelsky
Organizations
- National Aeronautics and Space Administration