Experimental analysis of hydrofoil hydroelastic trailing edge vibrations

This paper explores the conditions for hydro-elastic trailing edge vibrations on a NACA0015 aluminium hydrofoil clamped in a hydrodynamic tunnel. Test were performed for Reynolds numbers ranging from 2×10⁵ up to 9×10⁵ and various angle of attack, from 0 up to 10°. Laser vibrometry was used in order to describe the hydrofoil vibratory response. Time Resolved Particle Image Velocimetry (TR-PIV) was also used to visualise the flow and question the origin of the hydrodynamics excitation mechanism. This work aims to describe the different configurations generating strong coupling between the flow and a trailing edge structural eigenmode. It has been shown that vibrations of significant amplitude can be observed for a specific range of angle of attack from 3.5° to 8.5° and that the pressure surface boundary layer separation close to the trailing edge plays a key role in the hydrodynamics excitation mechanism

Tonal Noise Control Versus Performances on NACA0015 Hydrofoil

Strong correlation between boundary layer excitation and hydrofoil eigenmode occurs for specific angles of attack and Reynolds numbers, resulting in strong tonal noise emissions under certain circumstances. This study aims to analyze the performance of vibration control methods such as truncated trailing edge or boundary layer triggering. The study explores the conditions for hydro elastic trailing edge vibrations on a hydrofoil clamped in a hydrodynamic tunnel, with tests performed for Reynolds numbers up to 1.2 × 10⁶ and various angles of attack up to 10°. Experiments were conducted on a clamped 0.1 m chord NACA0015 aluminum hydrofoil, with measurements taken for both vibrations and hydrodynamic components such as lift, drag, and moment. The goal of the study is to closely understand the impact of vibration control on hydrofoil efficiency. This could be very beneficial for those who are working on optimizing profile design. The study first presents the experimental setup, followed by an analysis of the hydrofoil’s vibratory response and a presentation of the effectiveness of control solutions. Then, the performance of these solutions is discussed followed by a conclusion

Low speed flutter and post-critical behaviour of flat plate and NACA0018 section models in a wind tunnel

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Dynamic stall onset variation with reduced frequency for three stall mechanisms

A set of unsteady aerodynamic load measurement is performed on three oscillating airfoils with distinct stall mechanisms: a flat plate, a NACA0012, and a NACA0018. The airfoils are forced to oscillate in pitch around the stall angle of attack with prescribed frequency and amplitude. A criterion proposed by Sheng et al. is used to locate the onset of the flow separation process associated with dynamic stall, and quantify its variation with an equivalent reduced pitch rate. The validity of this criterion is tested for the three airfoils at low Reynolds number, Re = 2 × 10^4. Results are compared with the experimental data obtained by Sheng et al. at higher Reynolds number of Re = 1.5 × 10^6.The Nonlinear Tuned Vibration Absorber (NoVib

Analysing fluid loadings on moving bluff bodies using proper orthogonal decomposition

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