The challenge of stereo PIV measurements in the tip gap of a transonic compressor rotor with casing treatment

• Published in: Experiments in fluids Vol. 52; no. 3; pp. 581 - 590
• Main Authors: Voges, Melanie, Willert, Christian E., Mönig, Reinhard, Müller, Martin W., Schiffer, Heinz-Peter
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.03.2012; Springer
• Subjects: Applied fluid mechanics; Casing (material); Casing (process); Data processing; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Exact sciences and technology; Fluid dynamics; Fluid- and Aerodynamics; Fundamental areas of phenomenology (including applications); Heat and Mass Transfer; Hydraulic and pneumatic machinery; Instrumentation for fluid dynamics; Light sheets; Physics; Research Article; Rotors; Stators; Tip clearance; Transonic compressors; Light Sheet; Particle Image Velocimetry Measurement; Stereoscopic Particle Image Velocimetry; Particle Image Velocimetry Data; Particle Image Velocimetry; Turbomachine casing; Transonic flow; Test facilities; Stereoscopy; Particle image velocimetry; Compressors; Calibration; Experimental study; Velocity measurement
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-011-1061-y

This contribution is aimed at summarizing the effort taken to apply stereoscopic PIV (SPIV) measurements in the tip clearance of a transonic compressor rotor equipped with a casing treatment. A light sheet probe was placed downstream of the stator and aligned to pass the light sheet through a stator passage into the blade tip clearance of the rotor. A setup with three cameras has been used in order to record the entire 2C velocity field and the smaller area of 3C field of view at the same time instance for comparison with earlier 2C PIV results. A homogeneous seeding distribution was achieved by means of a smoke generator. The main emphasis of the SPIV measurement was to establish a data set with high spatial resolution close to the compressor casing, where the aerodynamic effects of a CT are known to be strong. The paper will discuss some major aspects of the utilized PIV data processing and point out a variety of frequently underestimated error sources that influence the overall quality of the recovered data in spite of the fact that the individual PIV recordings seemed to be of very good quality. Thus, the authors will not focus on the PIV results and related interpretation of the flow field, but on the optimization and procedures applied during setup of the experiment and data processing, respectively.