Time-Variant Aerodynamics for Torsional Motion of Large-Turning Airfoils.
GENERAL MOTORS CORP INDIANAPOLIS IN DETROIT DIESEL ALLISON DIV
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A cascade of five airfoil sections modelling the hub section of an advanced design turbine featuring a high inlet Mach number and 112 degrees of turning was evaluated at 4 steady-state conditions of varying exit Mach number and expansion ratio. The resulting steady-state airfoil surface pressures were compared to a state-of-the-art analytical prediction. A time-variant investigation was conducted at the 4 operating conditions of the steady-state experiment. Time-variant pressure signals were obtained from a Kulite-instrumented airfoil as the cascade was torsionally oscillated at four values of interblade phase angle per expansion ratio by computer-controlled electromagnetic drive systems. The dynamic pressure signals were evaluated in amplitude and phase lag referenced to blade motion and correlated with a state-of-the-art analytical prediction based on a flat-plate cascade. A quasistatic experiment was performed to relate the dynamic surface pressure amplitudes to those obtained by resetting the cascade to various temporal positions in the torsional cycle of oscillation. Author
- Fluid Mechanics
- Jet and Gas Turbine Engines