1. Figure 1
2. The majority of the research on dynamic stall has been motivated by its appl icaLion to he 1icopter retreating-blade st,all and to turbomachinery flows and has concentrated on airfoils subjected to sinusoidal pi!.ch oscillations of moderate III 1.e arid amp 1 itude. Recently, hov.cer, projected aircraft maneuverability enhancements' have stimulated interest i n t h v cas- of constant-rate,high-amp 1i t.iide pii.cb mot.iorr, as evidencby tlie experiments of Refs. 5-12 and the computational work of Refs. 13-i5. The study of constant-rate pitching, starting from a well-defined steady flow condition is also attractive sincc it. allows the experimental and computational investigations are therefore required in order to elucidate the effect of compressibility on dynamic stall.
3. To accomplish the above objectives, computations were performed for the flow configuration depicted in Figure 1. A NACA 0015 airfoil was pitched about a fixed axis and at a constant rate from zero incidence Lo a high angle of attack. Tlir freestream Mach number and chord Ilcynolds number varied over the ranges 0.2-0.6and 2 x lO!'-l x lo", respectively. The non-dimensional pitch rate O+ ranged from 0.02to 0.4, and different pitch-axis locations were also considered. Numerical results were obtained by solving the unsteady compressible mass-averaged Navier-Stokes equations using an.implicit algrjthm'nd an algebraic eddy viscosity turbulence model. 11. Method of Solu-!
4. Finally, the formulation o€ the problem is completed by imposing as an initial condition the computed flow at zero-degree angle of attack. I n addition, t.he airfoil accelerates to its final constant pitch rate as described in Ref. 1 4 ._ Numrrical . _ _ Procedure