On the applicability of background oriented optical tomography for large scale aerodynamic investigations

Density fields of the blade tip vortices from a helicopter in hover flight were visualized by a technique which does not require any installation on t he helicopter or close to it. The results illustrate an encouraging prospec t fur the applicability of the technique. It offers the capability of at le ast qualitative investigations of unsteady density fields even in full-scal e flight tests. The underlying principle is briefly described in this artic le and an extension to a three-dimensional quantitative technique by using multiple cameras is outlined.