Session: 31-10 Flow Control

Paper Number: 152491

Numerical Investigation of Passive and Active Flow Control Methods in a Low-Speed Multistage, Highly-Loaded Axial Compressor With Tandem Stator Configuration 

This paper presents a numerical investigation of the feasibility and effectiveness of flow control techniques applied to a low-speed multistage highly-loaded axial compressor with tandem stators. The study explores two main flow control configurations: a passive inter-stage recirculation channel in isolation, and its combination with synthetic jet actuation (SJA), a form of active flow control (AFC), using both steady (RANS) and unsteady (URANS) flow simulations. Given the high energy demands of synthetic jet actuation alone and the efficiency penalties often associated with passive endwall modifications, the combined use of a recirculation channel and SJA aims to balance effectiveness and energy efficiency. While previous research has largely focused on active flow control in isolated airfoils or single compressor stages, this work extends these techniques to a multistage configuration featuring highly-loaded tandem stator vanes.

To minimize computational cost, the front 2.5 stages of a multistage, low-speed research compressor are used as the reference geometry. The recirculation channel is positioned at the casing, connecting the endwall regions of the second stage rotor (suction) to the first stage stator (injection), with a simplified design using both injection and suction slots.

The injection system features a Coanda injector placed at two positions near the leading edges of the front and rear vanes, following insights gained from previous research on air injection in tandem stator configurations. For the suction, a suction patch is positioned at the second rotor outlet, as the optimal location and geometry are still under investigation.

To introduce regulated injection, the recirculation channel is coupled with a synthetic jet actuator (SJA) placed above the injector slot. By superimposing boundary conditions that replicate the behavior of an SJA onto the baseline channel flow, the study explores the impact of varying actuation frequencies, defined as multiples of the blade passing frequency (BPF), and different actuation phases, especially concerning the interaction between the injected flow and the downstream rotor.

Results indicate a reduction in total pressure losses in the first stage stator and second stage rotor for both flow control configurations, along with an increase in total pressure ratio across the two stages, and marginal efficiency gains observed in the combined system of recirculation channel and actuation. The study provides a detailed flow physics analysis of the impact on the secondary flow field, and addresses the challenges and limitations of integrating AFC in multistage environments, including the associated cost of actuation. Despite the relatively small improvements, the flow control techniques enhance endwall flow stability, which could be particularly beneficial for future compressor designs intended to push the aerodynamic limits of tandem stator configurations, especially where increased endwall flow separation and other aerodynamic issues arise.

Presenting Author: Gladys Gutiérrez Lupinta Technical University of Munich

Presenting Author Biography: Gladys Gutierrez is a PhD researcher at the Technical University of Munich (TUM), focusing on active flow control for compressor stages. With an interdisciplinary background in petroleum engineering, she worked in numerical modeling of oil and gas fields at Repsol for nearly six years before transitioning to research. She later completed a Master's in mathematics with a specialization in numerics at TUM in Germany, and for the past two years, she has been applying her skills to turbomachinery research.

Authors:

Gladys Gutiérrez Lupinta Technical University of Munich
Jannik Eckel Technical University of Munich
Volker Gümmer Technical University of Munich