Xavier Ottavy
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View article: Predicting Endwall Corner Separation in Compressor Cascades using RANS: Influence of Transition Treatment and Inflow Conditions
Predicting Endwall Corner Separation in Compressor Cascades using RANS: Influence of Transition Treatment and Inflow Conditions Open
This paper evaluates the predictive capabilities of state-of-the-art, steady-state RANS modelling approaches for the aerodynamics of the linear compressor cascade of the École Centrale de Lyon. The evaluation is based on comprehensive stud…
View article: ECL5/CATANA: Comparative Analysis of Advanced Blade Vibration Measurement Techniques
ECL5/CATANA: Comparative Analysis of Advanced Blade Vibration Measurement Techniques Open
A comprehensive understanding of aerodynamic instabilities, such as flutter, non-synchronous vibration (NSV), rotating stall, and forced response, is crucial for the safe and efficient operation of turbomachinery, particularly fans and com…
View article: ECL5/CATANA: Transition from Non-Synchronous Vibration to Rotating Stall at Transonic Speed
ECL5/CATANA: Transition from Non-Synchronous Vibration to Rotating Stall at Transonic Speed Open
Non-synchronous vibration (NSV), flutter, or rotating stall can cause severe blade vibrations and limit the operating range of compressors and fans. To enhance the understanding of these phenomena, this study investigated the corresponding…
View article: Experiments on Structurally Mistuned UHBR Open-Test-Case Fan ECL5/CATANA
Experiments on Structurally Mistuned UHBR Open-Test-Case Fan ECL5/CATANA Open
The operational capabilities of turbofan engines encounter limitations due to instabilities arising from tightly coupled interactions among aerodynamics, acoustics, and structural mechanics. Modern fans and compressors exhibit non-synchron…
View article: Towards Improved Turbomachinery Measurements: A Comprehensive Analysis of Gaussian Process Modeling for a Data-Driven Bayesian Hybrid Measurement Technique
Towards Improved Turbomachinery Measurements: A Comprehensive Analysis of Gaussian Process Modeling for a Data-Driven Bayesian Hybrid Measurement Technique Open
A cost-effective solution to address the challenges posed by sensitive instrumentation in next-gen turbomachinery components is to reduce the number of measurement samples required to assess complex flows. This study investigates Gaussian …
View article: Quantification of Blade Vibration Amplitude in Turbomachinery
Quantification of Blade Vibration Amplitude in Turbomachinery Open
Experimental monitoring of blade vibration in turbomachinery is typically based on blade-mounted strain gauges. Their signals are used to derive vibration amplitudes which are compared to modal scope limits, including a safety factor. Acco…
View article: UHBR Open-Test Case Fan ECL5/CATANA: Non-Linear Analysis of Non-Synchronous Blade Vibration at Part-Speed Conditions
UHBR Open-Test Case Fan ECL5/CATANA: Non-Linear Analysis of Non-Synchronous Blade Vibration at Part-Speed Conditions Open
The onset of non-synchronous vibrations has been predicted for a composite open-test-case UHBR fan geometry by time-linearized simulations at part-speed conditions. In the current study, time-accurate simulations with harmonic blade oscill…
View article: Experiments on Tuned UHBR Open-Test-Case Fan ECL5/CATANA: Performance and Aerodynamics
Experiments on Tuned UHBR Open-Test-Case Fan ECL5/CATANA: Performance and Aerodynamics Open
With the advancement of modern fan architectures, the lack of experimental benchmarks for the research community became apparent in the recent years. Enormous effort in the method development could not be validated on representative geomet…
View article: Experiments on Tuned UHBR Open-Test-Case Fan ECL5/CATANA: Stability Limit
Experiments on Tuned UHBR Open-Test-Case Fan ECL5/CATANA: Stability Limit Open
Research of the past decades has shown that the operating range of modern fans and compressors is often limited by aeroelastic phenomena before the onset of pure aerodynamic instability. Prediction of these mechanisms is challenging for st…
View article: Beneficial Effects of Guide Fins on Corner Separation
Beneficial Effects of Guide Fins on Corner Separation Open
Corner separation is a major phenomenon limiting the operability of aeronautical compressors. Passive control devices such as guide fins are envisioned to reduce its deleterious effects. In this paper, guide fins are optimized to reduce th…
View article: A CFD-Based Throughflow Solver Using Cascade Potential Theory for Axial Compressor Flow Modeling
A CFD-Based Throughflow Solver Using Cascade Potential Theory for Axial Compressor Flow Modeling Open
This paper describes the use of the Hess & Smith cascade potential method as an additional feature for throughflow modeling. This method is incorporated inside ASTEC, a CFD-based throughflow solver developed by Safran Tech providing local …
View article: Experimental monitoring of vibrations and the problem of amplitude quantification
Experimental monitoring of vibrations and the problem of amplitude quantification Open
Experimental monitoring of blade vibration in turbomachinery is typically based on blade-mounted strain gauges. Their signals are used to derive vibration amplitudes which are compared to previously determined modal scope limits, including…
View article: Improvement of measurement accuracy using Bayesian inference - Reduction of instrumentation effort in an axial compressor
Improvement of measurement accuracy using Bayesian inference - Reduction of instrumentation effort in an axial compressor Open
As the next generation of turbomachinery components becomes more sensitive to instrumentation intrusiveness, a reduction of the number of measurement devices required for the evaluation of performance is a possible and cost-effective way t…
View article: Experimental validation of a corner stall control methodology using parametrised guide fins
Experimental validation of a corner stall control methodology using parametrised guide fins Open
Corner separation is known to limit the operability of aeronautical compressors. Dedicated control devices such as guide fins are envisioned to reduce its negative effects. This paper presents a methodology based on RANS (Reynolds-Averaged…
View article: UHBR Open-Test-Case Fan ECL5/CATANA: Numerical Investigation Near the Stability Limit Including Aerodynamic Mistuning
UHBR Open-Test-Case Fan ECL5/CATANA: Numerical Investigation Near the Stability Limit Including Aerodynamic Mistuning Open
Non-synchronous blade vibration (NSV) has received enormous attention in turbomachinery research, since it can be safety critical and its occurrence is less predictable than typical aeroelastic instabilities such as flutter. Typical for fr…
View article: UHBR Open-Test-Case Fan ECL5/CATANA
UHBR Open-Test-Case Fan ECL5/CATANA Open
The application of composite fans enables disruptive design possibilities but increases sensitivity to multi-physical resonance between aerodynamic, structure dynamic and acoustic phenomena. As a result, aeroelastic problems increasingly s…
View article: The Unsteady Topology of Corner Separations
The Unsteady Topology of Corner Separations Open
As a compressor is throttled three-dimensional separations develop in the corners between the blades and annulus endwall. Surprisingly, little is understood about the unsteady topology of these separations. One of the problems in studying …
View article: INFLUENCE OF A TURBULENCE CONTROL SCREEN ON THE AERODYNAMIC AND AEROELASTIC BEHAVIOR OF A UHBR FAN
INFLUENCE OF A TURBULENCE CONTROL SCREEN ON THE AERODYNAMIC AND AEROELASTIC BEHAVIOR OF A UHBR FAN Open
Manuscript accepted for Proceedings of ASME Turbo Expo 2022 Turbomachinery Technical Conference and Exposition. GT2022June 13-17, 2022, Rotterdam, The Netherlands GT2022-81961
View article: Interpretation of stall precursor signatures-stable instabilities
Interpretation of stall precursor signatures-stable instabilities Open
A specific phenomenon that has been observed in many experimental studies on turbomachinery compressors and fans is discussed under the term “rotating instabilities”. It is associated to a local aerodynamic phenomenon, typically occurring …
View article: Interpretation of Stall Precursor Signatures
Interpretation of Stall Precursor Signatures Open
Unsteady aerodynamic phenomena appearing close to the stall boundary in axial fans and compressors have been the subject of extensive investigations. A particular phenomenon known as “rotating instabilities” typically occurs in the tip reg…
View article: The Unsteady Topology of Corner Separations
The Unsteady Topology of Corner Separations Open
As a compressor is throttled three-dimensional separations develop in the corners between the blades and annulus endwall. Surprisingly, little is understood about the unsteady topology of these separations. One of the problems with studyin…
View article: Aerodynamic Investigation of a Composite Low-Speed Fan for UHBR Application
Aerodynamic Investigation of a Composite Low-Speed Fan for UHBR Application Open
A composite fan stage representative of a modern Ultra High Bypass Ratio (UHBR) architecture has been investigated experimentally on a novel test facility at Ecole Centrale de Lyon. These measurements show indications for strong overloadin…
View article: UHBR Open-test-case fan ECL5/Catana, Part 2: Mechanical and aeroelastic stability analysis
UHBR Open-test-case fan ECL5/Catana, Part 2: Mechanical and aeroelastic stability analysis Open
Ultra High Bypass Ratio (UHBR) fan is a promising solution for the next decades to improve the turbofans efficiency and to reduce the environmental impact of the aeronautical propulsion. The high aspect ratio and the use of composite mater…
View article: UHBR Open-test-case fan ECL5/Catana, Part 1: Geometry and aerodynamic performance
UHBR Open-test-case fan ECL5/Catana, Part 1: Geometry and aerodynamic performance Open
Consequent application of composite rotors enables disruptive design possibilities but demands for a fundamental understanding of the dynamic behaviour to ensure robust design and safe operation. The sensitivity to multi-physical resonance…
View article: Compressible Modal Instability Onset in an Aerodynamically Mistuned Transonic Fan
Compressible Modal Instability Onset in an Aerodynamically Mistuned Transonic Fan Open
This paper describes observed modal oscillations arising from a feedback mechanism between an acoustic resonance in the exit flow channel and aerodynamic and aeroelastic disturbances in a transonic fan stage. During tests, the fan suffered…
View article: Quantification and Analysis of the Irreversible Flow Loss in a Linear Compressor Cascade
Quantification and Analysis of the Irreversible Flow Loss in a Linear Compressor Cascade Open
A local loss model and an integral loss model are proposed to study the irreversible flow loss mechanism in a linear compressor cascade. The detached eddy simulation model based on the Menter shear stress transport turbulence model (SSTDES…
View article: Observations on Rotating Instabilities and Spike Type Stall Inception in a High-Speed Multistage Compressor
Observations on Rotating Instabilities and Spike Type Stall Inception in a High-Speed Multistage Compressor Open
This work investigates high-frequency measurements for the contribution to the understanding of different stall inception types in high-speed multistage compressors. A 3.5-stage high-speed axial multistage compressor is investigated with a…
View article: Parameter study on numerical simulation of corner separation in LMFA-NACA65 linear compressor cascade
Parameter study on numerical simulation of corner separation in LMFA-NACA65 linear compressor cascade Open
Large-eddy simulation (LES) is compared with experiment and Reynolds-averaged Navier-Stokes (RANS), and LES is shown to be superior to RANS in reproducing corner separation in the LMFA-NACA65 linear compressor cascade, in terms of surface …
View article: Experimental investigation of flow field in a laboratory-scale compressor
Experimental investigation of flow field in a laboratory-scale compressor Open
The inner flow environment of turbomachinery presents strong three-dimensional, rotational, and unsteady characteristics. Consequently, a deep understanding of these flow phenomena will be the prerequisite to establish a state-of-the-art d…