Hybrid modelling for echo location and surface characterization

The scattering of sound from surfaces by rotating sources such as the tips of helicopter rotor blades can be used as a method of locating and ranging obstructions which may represent a physical danger to the craft. Modelling such systems presents some difficulties but these can be overcome using a c ombination of TLM and phase-coherent ray-tracing. This paper describes the hybrid approach, particularly, the techniques for interfacing. The applicat ion to the specific problem of the scattering of rotor-tip noise from reali stic targets involved the use of a simple PML and surface-conforming bounda ries. Copyright (C) 2001 John Wiley & Sons, Ltd.