Recent applications of particle image velocimetry in large-scale industrial wind tunnels

A variety of particle image velocimetry (PIV) systems for use in industrial wind tunnels have been developed at DLR in the past decade. Given the high operational costs of modern wind tunnels and the required instrumentation, the PIV system design emphasis concentrates on portability, modularity and reliability. Typical applications require large observation distances (> 5m) and relatively large observation areas (> 600 x 400 mm(2)) The recent introduction of digital imaging allows a rapid availability of the PIV data and feed-back during tunnel operation. The flexibility of these portable systems is illustrated by presenting several results of recent PIV applications: (1) blade/vortex interactions on a model helicopter rotor, (2) the flow downstream of an aircraft model in landing configuration in the 6 x 8 m(2) test section of the DNW Large Low Speed Testing facility (German-Dutch Wind Tunnel) and (3) the flow in the slat region of a two-dimensional high-lift air-foil. In each case the advantage of PIV in providing instantaneous velocity maps is apparent when compared to the time-averaged result. Current development efforts of extending the PIV method to provide three-dimensional data in wind tunnel environments are also given.