Session: 40-03 Compressor Secondary Flows and Interactions

Paper Number: 124307

124307 - The Unsteady Shock-Boundary Layer Interaction in a Compressor Cascade – Part 1: Measurements With Time-Resolved PIV 

In the framework of a DLR internal research project sources of unsteadiness of the shock-boundary layer interaction (SBLI) in a non-proprietary transonic cascade TEAMAero (TCTA) are investigated. The TCTA is operated in the transonic cascade wind tunnel of the DLR Institute of Propulsion Technology at chord-based Reynolds numbers of 1.3 - 1.4 × 10⁶ corresponding to inlet Mach numbers of 1.05 and 1.22.  From time-resolved (TR) shadowgraphs, the range of frequencies of shock vibration was determined in three neighboring  passages [Munoz Lopez et al 2023, ASME GT2023-102622]. In the present contribution we report on both snap-shot as well as time-resolved PIV (TR-PIV) performed on the TCTA to provide data for spectral and coherence analysis of the SBLI at high spatial and temporal resolution and to enable comparison with LES computations (presented in Part 2). TR-PIV is used to capture velocities in two narrow image regions at mid-span covering the inflowing BL, the shock interaction region and separation both on the suction side of the lower blade of the center passage. The third region partially covers the shear-layer in the wake downstream the trailing edge of the upper blade. In order to align both the instantaneous passage shock and velocimetry in the three regions, shadowgraph imagery is acquired synchronous with TR-PIV recordings. This arrangement allows observation of velocity and shock motion in spatially separated regions of the cascade flow. Details on the utilized instrumentation and data processing are provided with particular focus on the spectral and coherence analysis. TR velocities were sampled along wall-normal and chord-wise image columns and rows to allow for 2d FFT and 2d cross-correlation analysis between flow velocities and the time resolved shock position/velocity. Both allow observations on the propagation of disturbances originating from the unsteady shock as well as from shock-BL or shock-wake interactions. TR-PIV data allow further analysis of spatial modes at the relevant buffet frequencies through spectral proper orthogonal decomposition (SPOD).

Presenting Author: Joachim Klinner German Aerospace Center DLR, Institute of Propulsion Technology

Presenting Author Biography: 2001-07-01 to present | Research associate, Dept. (Engine Measurement Systems at DLR Institute of Propulsion Technology
2011-05-02 to 2017-10-16 | Doctoral studies "Development and assessment of volume resolving velocimetry for turbomachinery test facilities ", received PhD from University of Kassel, Dept. Electrical Engineering and Computer Science
1995-09-01 to 2000-09-01 | Dipl.-Ing. (FH) Photoengineering, Technische Hochschule Koeln, Nordrhein-Westfalen, DE;
https://orcid.org/0000-0003-2709-9664

Authors:

Joachim Klinner German Aerospace Center DLR, Institute of Propulsion Technology
Edwin J. Munoz Lopez German Aerospace Center DLR, Institute of Propulsion Technology
Alexander Hergt German Aerospace Center DLR, Institute of Propulsion Technology
Chris Willert German Aerospace Center DLR, Institute of Propulsion Technology