Flexible Oscillating Duct: An approach to a novel propulsor

Politis, G; Tsarsitalidis, V

dc.contributor.author	Politis, G	en
dc.contributor.author	Tsarsitalidis, V	en
dc.date.accessioned	2014-03-01T02:09:11Z
dc.date.available	2014-03-01T02:09:11Z
dc.date.issued	2012	en
dc.identifier.issn	01411187	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/29777
dc.subject	Biomimetic propulsion	en
dc.subject	Boundary element method	en
dc.subject	Unconventional propulsion	en
dc.subject	Unsteady wake rollup	en
dc.subject.other	A-train	en
dc.subject.other	Concept-based	en
dc.subject.other	Data generation	en
dc.subject.other	Design method	en
dc.subject.other	Design parameters	en
dc.subject.other	Free vortices	en
dc.subject.other	Hydrodynamic performance	en
dc.subject.other	Induced velocity	en
dc.subject.other	Motion data	en
dc.subject.other	Nonlinear pressure	en
dc.subject.other	Open water	en
dc.subject.other	Optimum designs	en
dc.subject.other	Oscillatory motion	en
dc.subject.other	Propulsors	en
dc.subject.other	Time stepping algorithms	en
dc.subject.other	Trailing edges	en
dc.subject.other	Unsteady wake	en
dc.subject.other	Vortex rings	en
dc.subject.other	Algorithms	en
dc.subject.other	Biomimetics	en
dc.subject.other	Boundary element method	en
dc.subject.other	Ducts	en
dc.subject.other	Ship propellers	en
dc.subject.other	Ships	en
dc.subject.other	Vortex flow	en
dc.subject.other	Ship propulsion	en
dc.subject.other	algorithm	en
dc.subject.other	boundary element method	en
dc.subject.other	hydrodynamics	en
dc.subject.other	oscillating flow	en
dc.subject.other	ship design	en
dc.subject.other	unsteady flow	en
dc.subject.other	vortex	en
dc.subject.other	wake	en
dc.subject.other	Scyphozoa	en
dc.title	Flexible Oscillating Duct: An approach to a novel propulsor	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.apor.2012.01.006	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.apor.2012.01.006	en
heal.publicationDate	2012	en
heal.abstract	Inspired by a jellyfish, where a bulk muscle oscillatory motion produces thrust, the initiative was taken to explore the propulsion capabilities of a new propulsor concept based on an oscillating/pulsating flexible duct. We name this device 'Flexible Oscillating Duct' (FOD). In this paper our purpose is threefold. Firstly, to understand the FOD's basic thrust producing mechanisms, secondly to present systematic FOD hydrodynamic performance results, necessary for its optimum design, and thirdly to compare the powering performance of ships equipped with FODs with those with conventional propellers. To this end, the problem of an actively deforming FOD, travelling with a given velocity in an infinitely extended fluid, is formulated and solved using an indirect Source-Doublet 3D-BEM, together with a time stepping algorithm capable of tracing the free vortex sheet geometry. A nonlinear pressure type Kutta condition is applied at the trailing edge of the FOD. With a mollifier based filtering of the induced velocities, the unsteady rollup pattern, created by the FOD motion, emerges. The produced pattern indicates that FOD thrust is produced through a train of coaxial vortex rings with circulations of alternating signs. FOD design parameters are then introduced and discussed and decisions were taken regarding creation of a FOD systematic series. A special data generation algorithm has been developed, capable of generating the unsteady thrust-producing motions for the FOD, including chord-wise flexibility. Using this data-generation code, we feed the BEM with systematic geometric and motion data and calculate the open water thrust, power and efficiency for the proposed FOD series. The solution of the FOD optimum design problem for real ships is then presented. The design method has been applied for three ship types. Comparisons show that the FOD is a promising system with propulsive coefficients superior to that of a conventional propeller. © 2012 Elsevier Ltd.	en
heal.journalName	Applied Ocean Research	en
dc.identifier.doi	10.1016/j.apor.2012.01.006	en
dc.identifier.volume	36	en
dc.identifier.spage	36	en
dc.identifier.epage	50	en