Load Calculations on Oscillating Airfoils using the
Beddoes-Leishman Dynamic Stall Model
Investigators: Michael J. Maresca, R. G. Rajagopalan (ISU)
Investigators: Dale E. Berg (Sandia National Laboratories)
Sponsored by : Sandia National Laboratories, Wind Energy Technology Dept.
Summary
Within the operational limits of rotorcraft, the rotor blades
are continuously subjected to large unsteady and vibratory loads
generated and transmitted by the rotor systems. The unsteadiness
of the rotor flow field can be mainly attributed to large, time
varying changes in the aerodynamic angle of attack. If this angle
of attack exceeds the static stall angle of the airfoil, and is
changing at a sufficient rate, transient flow separation will persist
and the airfoil is then said to be experiencing dynamic stall.
The Beddoes and Leishman semi-empirical dynamic stall model has been
used to make load calculations on airfoils. The major advantage of
this approach is that fairly accurate loads can be predicted in a
less computationally intensive manner over Navier-Stokes solutions.
The figure illustrates the results of the model as it simulates various
degrees of dynamic stall on the SAND 1850 airfoil and compares it to
wind tunnel test data.
