C. Polacsek, P. Lafon

High-Speed Impulsive (HSI) helicopter rotor noise, performance and local pressure measurements were performed in July-August 1990 in the ONERA SI-Modane wind tunnel fitted with acoustic lining. The acoustic lining improves quality of noise measurements, for the same aerodynamic performance, and makes acoustic averaged signals more workable, especially for HSI noise. This paper presents acoustic and aerodynamic results obtained by comparing two four-bladed rotors equipped with different sets of blade tip shapes : rectangular (rotor 7 A) and sweptback with anhedral (rotor 7 AD). The data analysis allows us to compare the aerodynamic performance of the two rotors and to verify that the shock delocalization in the forward direction is decreased with the sweptback parabolic tip blades (7 AD). A gain of 8 dBA on Sound Pressure Level (SPL) is obtained just before delocalization with the rotor 7 AD, and the aerodynamic efficiency is improved too. It confirms the interest of the "dihedral concept". Aerodynamic and acoustic results constitute a data base for the validation of computer codes under development.

17th European Rotorcraft Forum 1991, Berlin

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1991, 1991-08, 17th European Rotorcraft Forum Proceedings; S.473-482; 1991; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

acoustics, aerodynamics, helicopters, rotors, wind tunnel

Bestellbar

1991