Principles and application of velocimetry-based planar pressure imaging in compressible flows with shocks

The paper addresses the computation of pressure fields from velocimetry data, such as provided by Particle Image Velocimetry (PIV), with specific attention to its application in compressible flows with shocks. An essential extension with respect to incompressible flow is that in view of the variable density occurring in compressible flow, the velocimetry data has to be supplemented with additional relations, derived from the flow governing equations. Secondly, compressible flows display specific flow features, notably shocks but also thin shear layers, that pose particular difficulties for the flow velocity measurement itself, as well as for the subsequent determination of the pressure field. The present communication addresses the basic principles of the pressure-field extraction method, as well as its feasibility of application under realistic experimental conditions.