The applicability of the vortex method to cascades of oscillating airfoils is assessed by computing the unsteady incompressible lift, drag and moment for small incidence, thickness and vibratory displacement, the so-called 'classical' case. The results for a limited sampling of cascade geometries, reduced frequencies, vibration amplitudes and interblade phase angles are in excellent agreement with available analytical results. Instantaneous streamline patterns and discretized vorticity distributions are presented as an aid in physical understanding. The importance of the interblade phase angle as a governing parameter is confirmed. The effects of mean incidence, vibration amplitude and stagger angle are then studied. Important new results are presented showing the evolution of the classical reactions into the stalled-flow reactions with incidence, frequency and amplitude as parameters. In particular the complicated interaction is demonstrated between the structural frequency of the blades (considered as one of the 'inputs' to a nonlinear aeroelastic system) and the output frequency spectrum of the aerodynamic reactions. The major deficiency of the computer program is that the complete vibration mode and interblade phase angle must be specified at the outset of the computation. The implications for future direction of research, removal of the deficiency and subsequent design code implementation are discussed.
Computational aerodynamics of oscillating cascades with the evolution of stall
Rechenmodell zur Berechnung der aerodynamischen Verhaeltnisse an oszillierenden Kaskaden bei der Entstehung eines ueberzogenen Flugzustands
AIAA-Papers ; Jul ; 1-11
1987
11 Seiten, 20 Bilder, 3 Tabellen, 10 Quellen
Aufsatz (Konferenz)
Englisch
TIBKAT | 1977
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