D. Nicoud, J.M. Cailleau

Contrarotating high speed propellers are able to significantly reduce fuel consumption of high subsonic aircrafts. The achievement of this goal requires the optimization of the transonic flowfield on the blades in order to obtain high efficiency. For several years, 2D and 3D aerodynamic computational methods have been used to design high performance turbofans. A similar methodology can be developed for high speed propeller design, and this paper presents a typical application of such methods. we first present an application of the through-flow method. Then, a quasi geometrical method supplies the bidimensional profiles accounting for structural specifications, the tridimensional transonic flowfield is drawn by a 3D Euler solver on an appropriate domain. This code uses a multi-domains technique and includes the energy equation for non-constant rothalpy cases. Particular interest is focused on the Mach number distributions and on the shock strength. The final loss prediction is made by means of a shock loss model and a bidimensional boundary layer calculation based on the Euler static pressure distributions. The profile shapes are modified and the above process is repeated until the required deflection, a convenient throat margin, and sufficiently thin and well attached boundary layers are obtained. Finally, the global performances are issued from 3D Euler and boundary layer computations, completed by the calculation of secondary flow effects. After optimum profile shapes are obtained at cruise speed, the radiated sound of both propellers is needed to be known for estimation of acoustic performance and its environment impact at aircraft certification conditions. As predominent sources for far-field and near-field noise are different than in turbofan engines, new prediction techniques had to be developped. The prediction computer code based on the first Farassat integral solution in the time domain is shown applied to counterrotating propellers. Viscous wake and tip vortex rotor-rotor interaction are included to predict luading combination tones noise of aftward propeller. In order to obtain more realistic results. different but significant installation effects on radiated noise were also considered. Recent theoritical results are presented although no consistant comparison with test data had been carried out yet.

Eurpean Propulsion Forum, 1990, Köln

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1990, 1990-01, Eurpean Propulsion Forum: Future Civil Engines and the Protection of the Atmosphere - Proceedings; S.87-96; 1990; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

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Bestellbar

1990