Optical tomography for flow visualization of the density field around a revolving helicopter rotor blade

Abstract
In this paper we discuss a tomographic procedure for reconstructing the density field around a helicopter rotor blade tip from remote optical line-of-sight measurements. Numerical model studies have been carried out to investigate the influence of the number of available views, limited width viewing and ray bending on the reconstruction. Performance is measured in terms of the mean-square error. We found that very good reconstructions can be obtained using only a small number of views even when the width of view is smaller than the spatial extent of the object. An iterative procedure is used to correct for ray bending due to refraction associated with the sharp density gradients (shocks).