Comparative assessment of PIV-based pressure evaluation techniques applied to a transonic base flow

The pressure in a fluid flow is directly related to sound generation and surface loads. Both are important parameters in many engineering problems and the quantification of mean and fluctuating pressure is of great interest for efficient designs. Whereas surface pressure can experimentally be determined using pressure transducers and pressure-sensitive paint (PSP), PIV-based pressure determination Oudheusden (2013) offers unique capabilities beyond these more established measurement techniques. In contrast to pressure transducers and PSP, PIV-based pressure determination does not require making any modifications to wind tunnel models. This opens the door for pressure determination in configurations where making such modifications is not practical, e.g. thin airfoils. Moreover, it avoids the installation of large numbers of pressure transducers which is a common practice to obtain reliable surface loads. Another unique feature of PIV-based pressure determination is its inherent ability to provide simultaneous velocity and pressure data in the full flow field. This enables a better insight in the relation between fluid dynamics and surface loads or sound fields. Given these beneficial features, there has long been interest in PIV-based pressure determination. In recent years however, the technique has become increasingly feasible and appealing, mostly due to the development of (time-resolved) tomographic PIV (Elsinga et al. 2006; Scarano 2013). This is also the reason why its scale-up from small-size research environments is currently receiving attention in collaborative European framework programs 'AFDAR' and 'NIOPLEX'.