This thesis presents inviscid compressible simulations for the orthogonal blade-vortex
interaction. A numerical model between the tail rotor of a helicopter and the
trailing vortex system formed by the main rotor blades is assumed. The study takes
a ‘building-block’ approach to investigating this problem. Firstly, the impulsive
instantaneous blocking of the axial core flow by a flat plate is considered. In the
second step, the three-dimensional gradual cutting of the vortex by a sharp flat-plate
that moves at a finite speed through the vortex is performed. Finally the chopping
of the vortex by a blunt leading edge aerofoil, which incorporates both the blocking
effect and also the stretching and distortion of the vortex lines is studied. The
solutions reveal that the compressibility effects are strong when the axial core flow of
the vortex is impulsively blocked. This generates a weak shock-expansion structure
propagating along the vortex core on opposite sides of the cutting surface. The
shock and expansion waves are identified as the prominent acoustic signatures in the
interaction. In a simplified, two-dimensional axisymmetric model, the modelling of
the physical evolution of the vortex, including the evolution of the complex vortical
structures that controls the vortex core size near the cutting surface, are studied.
Furthermore, the three dimensional simulations revealed that there is a secondary
and a tertiary noise sources due to compressibility effects at the blade leading edge
and due to the shock-vortex interaction taking place on the blade, which is exposed
to a transonic free-stream flow.