Rotor Wake Tail Interactions Of A Helicopter Wind Tunnel Model With Various Rotor Head Configurations

Abstract

Experimental investigations are conducted on a twin-engine light utility helicopter wind tunnel model across various angles of attack. Six transient pressure transducers are installed on the vertical fin to examine the impingement effect of the wake of three rotor head configurations on the vertical tail. The analysis encompassed the root-mean-square (rms) values of surface pressure fluctuations and power spectral densities (PSD) for the tested angles of attack. For negative angles of attack, increased root-mean-square values indicate a highly unsteady flow environment at the uppermost pressure transducer. At positive angles of attack, the rotor wake impinges directly on the vertical tail, manifesting itself as significant pressure fluctuations PSD values at the first blade passing frequency. Furthermore, the maximum surface pressure fluctuation root-mean-square values, observed at various inflow angles exhibit distinct variations across the different rotor head configurations. The experiments are accompanied by numerical simulation and the rotor wake of the different rotor head variants are analyzed for selected angles of attack.