Interactions between the blades and vortical structures within the wake of a helicopter rotor are a significant
source of impulsive loading and noise, particularly in descending flight. Advances in the prediction and
understanding of such blade vortex interactions have been aided in recent years by the extensive experimental
dataset made available through the HART test programme. Brown’s Vorticity Transport Model was used to
predict the rotor blade loading, the resultant wake system and the acoustic noise radiation for the HART II
rotor. The vorticity conserving properties of the Vorticity Transport Model allow the detailed wake features
that are associated with blade vortex interactions to be resolved. The experimental airload data, in particular
the higher harmonic loading associated with blade vortex interactions, is matched well by the computations.
The computed vorticity distribution in the wake also shows good correlation with the experimentally measured
vortex positions. Including a representation of the fuselage within the computation yields marked improvement
in the prediction of the vortex positions compared to similar calculations with an isolated rotor. An accoustic
analysis, based on a Ffowcs-Williams Hawkings approach, is able to predict accurately the locations of the
sound pressure maxima and the upstream attenuation of the sound radiated by the rotor. The principal
discrepancies in airload, vortex position and acoustic prediction are confined almost exclusively to the rear of
the advancing side of the rotor and, if errors in measuring the blade deflection can be discounted, may be due
to minor inaccuracies in modelling the roll-up of the wake