Master thesis and internship[BR]- Master's thesis : Refinement of a predictive method for NSV Tip Vortex on high-speed compressor[BR]- Internship

Abstract

In this study, Enoval, a high-speed, low-pressure compressor developed by Safran Aero Boosters, is introduced. Despite its initial commendable performance in efficiency and fuel-to-rate ratio, Enoval encounters a concerning vibratory instability under conditions nearing stall. Through meticulous spectral analysis, this instability is identified as a NSV Tip Vortex phenomenon, triggered by the interaction of circumferentially propagating vortices with blade tip flow oscillations, consequently inducing substantial vibration levels.

Understanding the potential detrimental effects of NSV Tip Vortex on the blades, the study underscores the importance of pre-emptive prediction during the design phase rather than reliance on post-production testing. As a result, a predictive model is meticulously developed based on Brandstetter and Stapelfeldt's model, capable of anticipating NSV Tip Vortex occurrences based on intricate geometric and aerodynamic inputs. Application of this predictive model to Enoval demonstrates promising efficacy in accurately forecasting NSV Tip Vortex occurrences.

Moreover, a comprehensive parametric investigation delves into the nuanced influences of aerodynamic and geometric factors on NSV Tip Vortex, broadening the researches horizon. Insights gleaned from this investigation pave the path for devising preventive strategies geared towards shielding the rotor from NSV Tip Vortex-related risks. These strategies encompass a spectrum of interventions, including deliberate adjustments to aerodynamic parameters by innovative geometric treatments on the casing or the adoption of structural detuning techniques, which involve altering blade profiles to strategically modify natural frequencies along the rotor. While applied on Enoval, both preventive strategies appeared to effectively prevent NSV Tip Vortex. By shedding light on the underlying mechanisms of NSV Tip Vortex and proposing proactive measures, this study contributes to fortifying the operational resilience and longevity of advanced compressors like Enoval, or any other booster.