An unsteady lifting surface theory for ducted fan blades

Journal Article · Fri Jan 01 04:00:00 EST 1993 · Journal of Turbomachinery; (United States)

DOI:https://doi.org/10.1115/1.2929202· OSTI ID:5878480

Chi, R M ^[1]

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1. United Technologies Research Center, East Hartford, CT (United States). Dept. of Propulsion and Flight Systems

A frequency domain lifting surface theory is developed to predict the unsteady aerodynamic pressure loads on oscillating blades of a ducted subsonic fan. The steady baseline flow as observed in the rotating frame of reference is the helical flow dictated by the forward flight speed and the rotational speed of the fan. The unsteady perturbation flow, which is assumed to be potential, is determined by solving an integral equation that relates the unknown jump in perturbation velocity potential across the lifting surface to the upwash velocity distribution prescribed by the vibratory motion of the blade. Examples of unsteady pressure distributions are given to illustrate the differences between the three-dimensional lifting surface analysis and the classical two-dimensional strip analysis. The effects of blade axial bending, bowing (i.e., circumferential bending), and sweeping on the unsteady pressure load are also discussed.

• OSTI ID: 5878480
• Journal Information: Journal of Turbomachinery; (United States), Journal Name: Journal of Turbomachinery; (United States) Vol. 115:1; ISSN JOTUEI; ISSN 0889-504X
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330103* -- Internal Combustion Engines-- Turbine
AERODYNAMICS
COMPRESSORS
ENGINES
FLOW RATE
FLUID FLOW
FLUID MECHANICS
GAS FLOW
GAS TURBINE ENGINES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
MECHANICS
PRESSURE GRADIENTS
TURBINE BLADES