Carlos Alberto Tavera Guerrero

📅 Date & Time: 05 June 2025, 10:00–14:30
📍 Location: Lecture room E3, Osquars backe 18, KTH Royal Institute of Technology

About the Thesis

Current trends to enhance the aeroengines efficiency rely on more challenging working conditions with lighter, slender, and high-loaded blades. This high power-to-weight ratio can make the blades from the front stages more prone to face aeromechanic instabilities such as flutter. While key factors that affect flutter onset are well established in the literature, the effect of leading edge erosion mechanisms is vastly sparse or not reported. An oscillating transonic linear cascade has been conceptualized and developed for validation at KTH Royal Institute of Technology. In this test rig, an assessment of the effect of the leading edge erosion mechanism on the aeroelastic response is performed. The analyzed operating points are representative of a transonic axial compressor at part speed where a shock-induced separation mechanism is present. The aeroelastic measurements are performed at the first natural bending mode. The presented thesis comprises three key aspects: the aeroelastic response of a smooth reference case, the identification of limitations in roughness wall modeling, and the aeroelastic response under leading edge erosion mechanisms. For the latter, the blades have been subjected to an increase in roughness at the leading edge for the rough case, and the leading edge has been eroded and roughened for the eroded case. The results indicate that for the smooth case, the numerical models tend to overpredict the aeroelastic response downstream from the shock-induced separation compared to the experimental data. Surface roughness wall modeling showed limitations when separated regions exist at fully rough wall regimes. When erosion mechanisms are introduced, the numerical results predict an opposite trend compared to the experimental observations. The experimental data from the eroded case showed a local increase in the unsteady pressure amplitude while the phase remained unchanged.

Download the full thesis (DiVA)

"My perception of the PhD is that is a job that has a mix of rewards and tolerance to frustration, in particular in the experimental world. And as any job, if you want to keep going, in this context, you better have a good reason", says Carlos about his PhD experience.

Publications Included in the Thesis

The thesis is based on:

1. Blade oscillation mechanism for aerodynamic damping measurements at high reduced frequencies

2. Validation of Steady-State Aerodynamics in a Transonic Linear Cascade at Near Stall Conditions

3. Aeroelastic Response in an Oscillating Transonic Compressor Cascade—An Experimental and Numerical Approach

4. Numerical Surface Roughness Influence on the Aerodamping of an Axial Transonic Compressor at Nominal Speed and Part-Speed

PhD related project

ADiSS — Aeroelastic Damping in Separated Flows

Opponent

Prof. Dr. Ing. Dieter Peitsch , Technical University Berlin

Grading Committee

• Prof. Valery Chernoray , Chalmers University of Technology

• Dr. Sina Stapelfeldt  – Imperial College London

• Dr. Fanny Besem-Cordova , Cadence Design Systems

Supervisors

• Principal supervisor: Dr. Jens Fridh

• Co-supervisor: Dr. Mauricio Gutierrez Salas

• Co-supervisor: Tek-Lic. Nenad Glodic

Photo Highlights

Questions?

📩 For more information, feel free to contact Nenad Glodic .