BVI (blade vortex interaction) phenomena cause unsteady loading and noise in the helicopter rotor. It is difficult to accurately predict BVI aerodynamics and noise, because rotor wake and tip-vortices are numerically dissipated. In the present study, CFD and a time-marching free-wake coupling analysis were used to describe inflow and outflow without wake dissipation. Rotor noise was also computed using the Farassat formula, derived from the Ffowcs-Williams Hawkings equation. To validate aerodynamics and the noise prediction solver, a two-blade rotor was simulated and the results were compared with experimental data. To investigate the vortex interaction of a multi-blade rotor, a four-blade rotor was also simulated. In a slow descent flight condition, tip vortices are merged at the advancing side. The merged tip-vortex and blade interaction were simulated and are discussed in this paper.