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Dynamic response and stability of fl...

Chae, Eun Jung.

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Dynamic response and stability of flexible hydrofoils in incompressible and viscous flow.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Dynamic response and stability of flexible hydrofoils in incompressible and viscous flow./
Author:	Chae, Eun Jung.
Description:	159 p.
Notes:	Source: Dissertation Abstracts International, Volume: 76-09(E), Section: B.
Contained By:	Dissertation Abstracts International76-09B(E).
Subject:	Naval engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3701804
ISBN:	9781321727104

Dynamic response and stability of flexible hydrofoils in incompressible and viscous flow.
Chae, Eun Jung.

Dynamic response and stability of flexible hydrofoils in incompressible and viscous flow. - 159 p.

Source: Dissertation Abstracts International, Volume: 76-09(E), Section: B.

Thesis (Ph.D.)--University of Michigan, 2015.

It is important to understand and accurately predict the static and dynamic response and the stability boundary of flexible hydrofoils to ensure their structural safety, facilitate the design and optimization of new and existing concepts, and test the feasibility of using advanced materials and control concepts.

ISBN: 9781321727104Subjects--Topical Terms:

3173824
Naval engineering.

Dynamic response and stability of flexible hydrofoils in incompressible and viscous flow.
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020 $a 9781321727104
035 $a (MiAaPQ)AAI3701804
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040 $a MiAaPQ $c MiAaPQ
100 1 $a Chae, Eun Jung. $3 3181414
245 1 0 $a Dynamic response and stability of flexible hydrofoils in incompressible and viscous flow.
300 $a 159 p.
500 $a Source: Dissertation Abstracts International, Volume: 76-09(E), Section: B.
500 $a Adviser: Yin Lu Young.
502 $a Thesis (Ph.D.)--University of Michigan, 2015.
520 $a It is important to understand and accurately predict the static and dynamic response and the stability boundary of flexible hydrofoils to ensure their structural safety, facilitate the design and optimization of new and existing concepts, and test the feasibility of using advanced materials and control concepts.
520 $a In particular, with recent advancements in material and computational modeling and design, it is possible to take advantage of advanced materials and the fluid-structure interaction (FSI) response to improve the hydrodynamic and structural dynamic performance of flexible hydrofoils. As interest in maritime applications of lightweight, flexible hydrofoils increases, understanding the flow-induced vibration response and stability becomes more important to ensure structural safety and to optimize performance and control.
520 $a Hence, the objectives of this dissertation are the following: 1) to derive and validate the FSI response and stability boundary of flexible hydrofoils in incompressible and viscous flow; 2) to investigate the influence of inflow velocity, angle of attack, and relative mass ratio on the flow-induced vibrations of flexible hydrofoils; and 3) to investigate the influence of the flow-induced bend-twist coupling of flexible hydrofoils.
520 $a A loose hybrid coupled (LHC) method is presented to predict the dynamic FSI response and stability of flexible hydrofoils in incompressible and viscous flow.
520 $a The results indicate that both the flutter and divergence speeds decrease when the relative mass ratio (i.e, solid-to-fluid added mass ratio, $sqrt{mu}$) decreases, and that linear potential theory over-predicts the flutter speed at the low mass ratio regime [special characters omitted]. It should be noted that although the static divergence is insensitive to variations in solid mass, the divergence speed decreases with decreasing [special characters omitted] because of increases in the fluid density, which increases the fluid disturbing force.
520 $a The results indicate that static divergence governs for [special characters omitted], dynamic divergence governs for [special characters omitted], and flutter governs for [special characters omitted]. The in-water natural frequencies of flexible hydrofoils are much lower than in-air natural frequencies because of added mass effects. The in-water natural frequencies vary with inflow velocity, angle of attack, and relative mass ratio due to flow-induced bend-twist coupling and viscous effects on the system's stiffness and damping terms.
520 $a The results also show that vortex shedding frequencies of flexible hydrofoils can be much lower than those of rigid hydrofoils, and that the wake patterns can differ greatly between rigid and flexible hydrofoils. In particular, when the vortex shedding frequencies snap into one of the natural frequencies of the flexible hydrofoil (i.e, a lock-in condition of flexible hydrofoils), the vibration and load fluctuation amplitudes are amplified.
520 $a The results further show that the inviscid simulations tend to overestimate the total loss factors for cases with low mass ratios ([special characters omitted]), because of viscous and flow-induced bend-twist coupling effects.
520 $a Overestimation of total loss factors increases with higher inflow velocity and lower relative mass ratio, and can be dangerous, potentially leading to earlier onset of fatigue, louder noise and vibrations.
590 $a School code: 0127.
650 4 $a Naval engineering. $3 3173824
650 4 $a Ocean engineering. $3 660731
690 $a 0468
690 $a 0547
710 2 $a University of Michigan. $b Naval Architecture and Marine Engineering. $3 3175806
773 0 $t Dissertation Abstracts International $g 76-09B(E).
790 $a 0127
791 $a Ph.D.
792 $a 2015
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3701804