Experimental and numerical FSI study of compliant hydrofoils

Abstract

A propulsion system based on tandem hydrofoils is studied experimentally and numerically. An experimental measurement system is developed to extract hydrodynamic loads on the foils and capture their twisting deformation during operation. The measured data allowed us to assess the efficiency of the propulsion system as a function of travel speed and stroke frequency. The numerical simulation of the propulsion system is also presented and involves 3D, full-scale fluid-structure interaction (FSI) computation of a single (forward) foil. The foil is modeled as a combination of the isogeometric rotation-free Kirchhoff-Love shell and bending-stabilized cable, while the hydrodynamics makes use of the finite-element-based arbitrary Lagrangian-Eulerian variational multiscale formulation. The large added mass is handled through a quasi-direct FSI coupling technique. The measurement data collected is used in the validation of the FSI simulation, and excellent agreement is achieved between the predicted and measured hydrodynamic loads and foil twisting motion.

A node-numbering-invariant directional length scale for simplex elements

“…38 The ALE-SUPS, RBVMS and ALE-VMS have been applied to many classes of FSI, MBI and fluid mechanics problems. The classes of problems include ram-air parachute FSI, 32 wind-turbine aerodynamics and FSI, [39][40][41][42][43][44][45][46][47][48][49] more specifically, vertical-axis wind turbines, 50,51,48,49 floating wind turbines, 52 wind turbines in atmospheric boundary layers, 53,[47][48][49] and fatigue damage in wind-turbine blades, 54 patient-specific cardiovascular fluid mechanics and FSI, 55,25,[56][57][58][59][60] biomedical-device FSI, [61][62][63][64][65][66] ship hydrodynamics with free-surface flow and fluid-object interaction, 67,68 hydrodynamics and FSI of a hydraulic arresting gear, 69,70 hydrodynamics of tidal-stream turbines with freesurface flow, 71 passive-morphing FSI in turbomachinery, 72 bioinspired FSI for marine propulsion, 73,74 bridge aerodynamics and fluid-object interaction, [75]…”

Space–time Isogeometric flow analysis with built-in Reynolds-equation limit

“…31 They have been applied to many classes of FSI, MBI and fluid mechanics problems. The classes of problems include wind-turbine aerodynamics and FSI, [32][33][34][35][36][37][38][39][40][41][42] more specifically, vertical-axis wind turbines, [41][42][43][44] floating wind turbines, 45 wind turbines in atmospheric boundary layers, [40][41][42]46 and fatigue damage in wind-turbine blades, 47 patient-specific cardiovascular fluid mechanics and FSI, 19,[48][49][50][51][52][53] biomedical-device FSI, [54][55][56][57][58][59] ship hydrodynamics with free-surface flow and fluid-object interaction, 60,61 hydrodynamics and FSI of a hydraulic arresting gear, 62,63 hydrodynamics of tidal-stream turbines with free-surface flow, 64 bioinspired FSI for marine propulsion, 65,66 bridge aerodynamics and fluid-object interaction, [67][68][69] and mixed ALE-VMS/Immersogeometric computations…”

FSI modeling of a propulsion system based on compliant hydrofoils in a tandem configuration

“…In this section, we briefly describe the propulsion system analyzed, which is the Mirage Drive designed and built by Hobie Cat Co. For more details the reader is referred to [6], where such a measurement system is presented in detail. Here the field test procedures are adapted for simultaneous measurement of the hydrodynamic loads on both the front and back foils.…”

“…In the present paper, we perform fluid-structure interaction (FSI) analysis of a bioinspired propulsion system utilizing compliant hydrofoils. This work, which is an extension of a recent experimental and numerical FSI study of a single compliant hydrofoil [6], presents, for the first time, full-scale FSI simulation of two compliant hydrofoils in a tandem configuration.…”

“…Nowadays, the concept of bioinspired (or biomimetic) engineering is widely used in the design of propulsive and energy harvesting systems. Examples of such systems include micro aerial vehicles (MAVs) [61,63,67,77,82], vertical-axis wind turbines (VAWTs) placed in arrays [25,45], and recreational water sports vehicles, like kayaks [6]. The main hypothesis behind the bioinspired engineering concept is that e ciency of engineering systems or devices may be improved by mimicking the shape, structure, and motion of various species (e.g., birds, insects, or fish), which have these characteristics optimized in the long span of their evolution.…”