PIV-based pressure measurement

Abstract

The topic of this paper is a review of the approach to extract pressure fields from flow velocity field data, typically obtained with Particle Image Velocmetry (PIV), by combining the experimental data with the governing equations. Although the basic working principles on which this procedure relies have been known for quite some time, the recent expansion of PIV capabilities have greatly increased its practical potential, up to the extent that nowadays a time-resolved volumetric pressure determination has become feasible. This has led to a novel diagnostic methodology for determining the instantaneous flow field pressure in a nonintrusive way, which is rapidly finding acceptance in an increasing variety of application areas. The current review describes the operating principles, illustrating how the flow governing equations, in particular the equation of momentum, are employed to compute the pressure from the material acceleration of the flow. Accuracy aspects are discussed in relation to the most dominating experimental influences, notably the accuracy of the velocity source data, the temporal and spatial resolution and the method invoked to estimate the material derivative. In view of its nature of an emerging technique, recently published dedicated validation studies will be given specific attention. Different application areas are addressed, including turbulent flows, aeroacoustics, unsteady wing aerodynamics and other aeronautical applications.

Experimental comparison of a wind-turbine and of an actuator-disc near wake

“…The derivation of the pressure from SPIV data has been extensively addressed in many fields of research, as by Liu and Katz (2006), Raffel et al (1998), Ragni et al (2011), andvan Oudheusden (2013). Applications in phase-locked environments for propeller and wind-turbines have allowed reconstructing the 3D periodic pressure fields and subsequently non-intrusively obtaining loads on the rotor blade by Ragni et al (2011).…”

“…In the present study, the leapfrogging is triggered by an asymmetry of the blade pitch angle, as by Lignarolo et al (2014a). The use of an adapted formulation of the momentum equation in differential form allowed to compute the pressure field and stagnation enthalpy around the rotor and the porous disc directly from the velocity data in the incompressible regime (Ragni et al, 2011;2012;and van Oudheusden, 2013). The out-of-plane vorticity field is calculated by differentiation of the time-average velocity field with a central difference scheme.…”

A posteriori uncertainty quantification of PIV-based pressure data

“…Particle image velocimetry (PIV) is nowadays recognized as a reliable tool for the determination of the instantaneous static pressure in two-or three-dimensional flow fields (van Oudheusden 2013). The main advantage of the PIVbased pressure reconstruction with respect to conventional pressure probes (e.g., pressure transducers or microphones) is the instantaneous 2D or 3D pressure field determination, without the need of an expensive design and manufacturing of models where densely distributed sensors are installed (Ragni et al 2011).…”

“…72 Page 2 of 15 pressure (van Oudheusden 2013). Applying the divergence operator to the momentum equation and assuming incompressible flow, the Poisson equation for pressure follows:…”

Large-scale volumetric pressure from tomographic PTV with HFSB tracers

“…become possible from tomographic particle image velocimetry (PIV) measurements as reviewed in van Oudheusden (2013). The appealing aspect of the approach is that it avoids the requirement of instrumentation of wind-tunnel models using pressure transducers.…”