21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-5.4.3

ON THE STEADY AND UNSTEADY EFFECTS OF BLADE ROW SPACING IN A COUNTER-ROTATING DUCTED PROPFAN

Wallscheid L.
DLR, Germany

Keywords: steady and unsteady effects, blade row spacing, counter-rotating ducted propfan

Steady and time-accurate unsteady 2D viscous calculations have been carried out on a cylindrical slice of a transonic counter rotating ducted propfan to study the effects of blade row spacing on the steady and unsteady flow behavior. Therefore three different spacings between the two rotors have been simulated. The steady results show deviations for the individual cases, probably due to various error sources in the approach. The results show that there is a strong dependency of the distance on the unsteady flow. Especially between the rotors the upstream potential effects of the second rotor are apparent. Behind the rotors the amplitudes are smaller but still dependent on the blade row spacing. The amplitude of the unsteady contributions is dependent upon the circumferential position in the blade passage. The envelopes of the unsteady variables are similar between the rotors regardless of the axial spacing. However, downstream of rotor 2 the shape of the envelopes varies with the blade row spacing.

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