Session: 40-08 Compressor Flow Control Approaches

Paper Number: 129548

129548 - A Framework and Approach for Leveraging Unsteady Response in Turbocompressor Flowfields 

The performance and operability demands on turbocompressors continue to increase as system designers look towards optimized arrangements that enhance system flexibility to highly variable conditions, increase the density of energy transfer, and reduce the amount of lost work. Turbocompressor flowfields can be classified into two flow regimes, demarcated by a stability boundary representing an operational limit. For aerodynamic loadings above this stability limit, the flowfield is highly complex, exhibiting a broad range of temporal and spatial features, limiting work transfer and increasing entropy production. Blade-level instabilities, such as rotating stall, are the result of deleterious flowfield features, sensitive to perturbation, which have grown with aerodynamic loading.

Based on the thesis that critical destabilizing flow structures exhibit coherent response to periodic excitation and can be usefully organized via tuned periodic forcing, the work presented herein emphasizes the dynamical behavior of a representative compressor flowfield under periodic transients and the difficulty in extracting useful information on flowfield response in the post-stall regime. A new analysis approach is developed that enables better understanding of the rotating stall process, providing guidance for the use of data-driven tools and new approaches for control development. Emerging decomposition and operator-based analysis approaches are borrowed from dynamical system modeling to aid in deducing the coherent structures, their unforced behaviors, and critical forcing frequencies. In this work, linear stability analysis and resolvent analysis are used to identify the underlying flow structures contributing to the onset of instability. Through a demonstrated surrogate model for compressor stability, a conceptual framework and practical approach are developed such that the unsteady response of turbocompressor flows to tuned forcing can be leveraged to manipulate deleterious flowfield features, creating new potential pathways to achieve wider operability and enhance the transfer of usable work.

Presenting Author: Eric Krivitzky Thermofluid Research Lab, LLC

Presenting Author Biography: Dr. Eric Krivitzky is a specialist in aerodynamic design and development of advanced turbomachinery components, models, and systems. Over the last 20 years, Dr. Krivitzky has conducted research, design, and development efforts across a broad range of applications and machine architectures, with a focus on radial and mixed-flow compressor stability and range. Specific interests include enhancing stability, range and performance for transonic centrifugal and mixed-flow compressors in both ground and air propulsion platforms, radial inflow turbine performance under unsteady, time-periodic and non-uniform inflow conditions, opportunities for behavior modification with closely-coupled components, and leveraging resonance structures within the flowfield for preferential behaviors. He received his Bachelor's and Master’s degrees from Cornell University and his doctorate from Dartmouth College.

Authors:

Eric Krivitzky Thermofluid Research Lab, LLC
Louis Larosiliere Elliott Group