The aerodynamics of a cascade of airfoils oscillating in torsion about the midchord is investigated experimentally at a large mean incidence angle and, for reference, at a low mean incidence angle. The airfoil section is representative of a modem, low aspect ratio, fan blade tip section. Time-dependent airfoil surface pressure measurements were made for reduced frequencies of up to i.2 for out-of-phase oscillations at a Mach number of 0.5 and chordal incidence angles of 0°and 10°; the Reynolds number was 0.gx10 6. For the 10°chordal incidence angle, a separation bubble formed at the leading edge of the suction surface. The separated flow field was found to have a dramatic effect on the chordwise distribution of the unsteady pressure.In this region, substantial deviations from the attached flow data were found with the deviations becoming less apparent in the aft region of the airfoil for all reduced frequencies. In particular, near the leading edge the separated flow had a strong destabilizing influence while the attached flow had a strong stabilizing influence.

No abstract

No abstract

No abstract

Three-dimensional linearized solvers are being developed to predict the multiblade row unsteady aerodynamics that drive HCF. However, to take advantage of the significant computational timesavings offered by linearized analyses, it is imperative that they be validated with appropriate benchmark data prior to turbomachinery design utilization. This paper addresses this need for LINFLUX-3D, a three-dimensional linearized Euler solver. This task is accomplished by simulating the unsteady flow through the IGV's generated by a downstream rotor. The 1GV steady flow and the rotor-lGV interaction generated unsteady aerodynamics on the IGV row are predicted for both a subsonic and transonic rotor condition. These simulations are then correlated with corresponding benchmark data, including both 90% span IGV surface steady and unsteady pressures and the IGV passage flow field. Nomenclature SuperscriptsAbstract bij Dirac delta δ, difference operator, () -() E, total internal energy fi unsteady flux vector, j direction