Particle Image Velocimetry in a High-Speed Short-Duration Turbine Rig

Abstract

This article presents the implementation of a Particle Image Velocimetry (PIV) into the high-speed short-duration rotating turbine facility of the von Karman Institute. The advantage of PIV as a whole field measurement is emphasized in such circumstances for which the use of optical technique can drastically reduce the number of tests and the need for multiple intrusive expensive probes, ultimately lowering the testing cost. Practical solutions were demonstrated that address various challenges for the effective application of PIV. An endoscope delivered the laser sheet to the region of interest and a planoconcave window provided optical access for the measurement in the annular test section. A high-speed laser system and a high-speed camera were synchronized at 1 kHz sampling rate. Complementary measurements and dedicated image processing were performed to ensure the synchronization of the PIV images with the rotor position that was monitored through an encoder. The region of interest was the blade-to-blade plane at the 58% span turbine exit on a rectangular field of view covering approximately one rotor pitch and 0.15 rotor axial chord from the rotor trailing edge. Phase-locked-average velocity fields are obtained from PIV and compared against steady-state Reynolds Averaged Navier Stokes (RANS) simulations along with four-hole probe measurement results. Together with an uncertainty analysis, the results demonstrate the promising robustness and accuracy of PIV. A practical guideline for PIV application in such kind of turbine test rigs is provided as a conclusion of the paper.

A fluorescent PIV technique for turbomachinery flows

“…Besides, the employment of pricey high-speed cameras should be avoided under such circumstances due to possible damage to the image sensor. The removal of the undesired reflection was achieved in the fluorescent particle images as shown in figure 13 The PLA method and the simulation setup are described in [7] and [8], respectively. Figure 15 shows yaw angle profiles extracted from figure 14 (c)-(e) along with the dotted lines 𝐿 1 and 𝐿 2 .…”

“…The total seeding mass flow rate injected through the seeding probes is estimated to be less than 0.2% of the main flow. The detailed test setup and processing method are described in [7].…”

“…In total 250 and 229 datasets were applicable for Mie scattering and fluorescent PIV-PLA. The PLA method and the simulation setup are described in[7] and[8], respectively. Figure15shows yaw angle profiles extracted from figure14 (c)-(e) along with the dotted lines 𝐿 1 and 𝐿 2 .…”