The influence of fluid–structure interaction on cloud cavitation about a rigid and a flexible hydrofoil. Part 3

Experimental studies of the influence of fluid–structure interaction on cloud cavitation about a stiff stainless steel (SS) and a flexible composite (CF) hydrofoil have been presented in Parts I (Smith et al., J. Fluid Mech., vol. 896, 2020a, p. A1) and II (Smith et al., J. Fluid Mech., vol. 897, 2020b, p. A28). This work further analyses the data and complements the measurements with reduced-order model predictions to explain the complex response. A two degrees-of-freedom steady-state model is used to explain why the tip bending and twisting deformations are much higher for the CF hydrofoil, while the hydrodynamic load coefficients are very similar. A one degree-of-freedom dynamic model, which considers the spanwise bending deflection only, is used to capture the dynamic response of both hydrofoils. Peaks in the frequency response spectrum are observed at the re-entrant jet-driven and shock-wave-driven cavity shedding frequencies, system bending frequency and heterodyne frequencies caused by the mixing of the two cavity shedding frequencies. The predictions capture the increase of the mean system bending frequency and wider bandwidth of frequency modulation with decreasing cavitation number. The results show that, in general, the amplitude of the deformation fluctuation is higher, but the amplitude of the load fluctuation is lower for the CF hydrofoil compared with the SS hydrofoil. Significant dynamic load amplification is observed at subharmonic lock-in when the shock-wave-driven cavity shedding frequency matches with the nearest subharmonic of the system bending frequency of the CF hydrofoil. Both measurements and predictions show an absence of dynamic load amplification at primary lock-in because of the low intensity of cavity load fluctuations with high cavitation number.

Download Full-text

Fluid Structure Interactions for Blast Wave Mitigation

Journal of Applied Mechanics ◽

10.1115/1.4002758 ◽

2011 ◽

Vol 78 (3) ◽

Cited By ~ 11

Author(s):

Wen Peng ◽

Zhaoyan Zhang ◽

George Gogos ◽

George Gazonas

Keyword(s):

Shock Wave ◽

Blast Wave ◽

Fluid Structure Interaction ◽

Wave Formation ◽

Plate Motion ◽

Fluid Structure Interactions ◽

Free Standing ◽

Fluid Structure ◽

Structure Interaction ◽

Shock Wave Formation

The dynamic response of a free-standing plate subjected to a blast wave is studied numerically to investigate the effects of fluid-structure interaction (FSI) in blast wave mitigation. Previous work on the FSI between a blast wave and a free-standing plate (Kambouchev, N., et al., 2006, “Nonlinear Compressibility Effects in Fluid-Structure Interaction and Their Implications on the Air-Blast Loading of Structures,” J. Appl. Phys., 100(6), p. 063519) has assumed a constant atmospheric pressure at the back of the plate and neglected the resistance caused by the shock wave formation due to the receding motion of the plate. This paper develops an FSI model that includes the resistance caused by the shock wave formation at the back of the plate. The numerical results show that the resistance to the plate motion is especially pronounced for a light plate, and as a result, the previous work overpredicts the mitigation effects of FSI. Therefore, the effects of the interaction between the plate and the shock wave formation at the back of the plate should be considered in blast wave mitigation.

Download Full-text

Dynamic load and stress analysis of a large horizontal axis wind turbine using full scale fluid-structure interaction simulation

Renewable Energy ◽

10.1016/j.renene.2019.03.053 ◽

2019 ◽

Vol 140 ◽

pp. 212-226 ◽

Cited By ~ 12

Author(s):

G. Santo ◽

M. Peeters ◽

W. Van Paepegem ◽

J. Degroote

Keyword(s):

Wind Turbine ◽

Stress Analysis ◽

Dynamic Load ◽

Fluid Structure Interaction ◽

Full Scale ◽

Horizontal Axis ◽

Horizontal Axis Wind Turbine ◽

Fluid Structure ◽

Structure Interaction ◽

Interaction Simulation

Download Full-text

A Technique For Lock-In Prediction On A Fluid Structure Interaction Of Naca 0012 Foil With High Re

EMITTER International Journal of Engineering Technology ◽

10.24003/emitter.v8i2.543 ◽

2020 ◽

pp. 495-509

Author(s):

Nu Rhahida Arini ◽

Stephen R. Turnock ◽

Mingyi Tan

Keyword(s):

Interaction Analysis ◽

Fluid Structure Interaction ◽

Total Force ◽

Transform Method ◽

Fluid Structure ◽

Structure Interaction ◽

Reynolds Number Flow ◽

History Of ◽

Lock In ◽

Naca 0012

A numerical lock-in prediction technique of a NACA 0012 hydrofoil, immersed in a flow having a Re of 3.07x106 is proposed in this paper. The technique observes the foil’s response as part of a fluid-structure interaction analysis. The response is modelled by foil’s vibration which is represented by spring and damper components. The technique identifies and predicts the foil’s lock-in when it vibrates. The prediction is examined using the Phase Averaged Method which employs the Hilbert Transform Method. The aim of this paper is to propose a numerical way to identify a lock-in condition experienced by a NACA 0012 foil in a high Reynolds number flow. The foil’s mechanical properties are selected and its motions are restricted in two modes which are in the pitch and heave directions. The rotational and transverse lock-in modes are identified in the model. The existence of lock-in is verified using pressure distribution plot, the history of trailing edge displacement and fluid regime capture. The history of total force coefficients is also shown to justify the result. The result shows that the technique can predict reliably the lock-in condition on the foil’s interaction. Three main fluid induced vibration frequencies are generated in the interaction. None of them are close to natural frequency of the foil and lock-in is apparently not found in the typical operational condition.

Download Full-text