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1

Dolphin-Inspired Target Detection for Sonar and Radar

Leighton T., White P.

Archives of Acoustics

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2014

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Vol. 39, No. 3

319--332

EN

Gas bubbles in the ocean are produced by breaking waves, rainfall, methane seeps, exsolution, and a range of biological processes including decomposition, photosynthesis, respiration and digestion. However one biological process that produces particularly dense clouds of large bubbles, is bubble netting. This is practiced by several species of cetacean. Given their propensity to use acoustics, and the powerful acoustical attenuation and scattering that bubbles can cause, the relationship between sound and bubble nets is intriguing. It has been postulated that humpback whales produce ‘walls of sound’ at audio frequencies in their bubble nets, trapping prey. Dolphins, on the other hand, use high frequency acoustics for echolocation. This begs the question of whether, in producing bubble nets, they are generating echolocation clutter that potentially helps prey avoid detection (as their bubble nets would do with man-made sonar), or whether they have developed sonar techniques to detect prey within such bubble nets and distinguish it from clutter. Possible sonar schemes that could detect targets in bubble clouds are proposed, and shown to work both in the laboratory and at sea. Following this, similar radar schemes are proposed for the detection of buried explosives and catastrophe victims, and successful laboratory tests are undertaken.

2

Wpływ warunków nawigacyjnych na parametry pracy układu napędowego statku śródlądowego

Skupień E., Restel F. J.

TTS Technika Transportu Szynowego

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2013

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R. 20, nr 10

3513--3520

PL

Parametry pracy układu napędowego statku, zależą od wytwarzanego przezeń naporu i koniecznego do pokonania oporu wytwarzanego przez jednostkę. Opór jaki stawia woda zależy od warunków nawigacyjnych panujących na drodze wodnej. W referacie przedstawiono wpływ warunków nawigacyjnych na pracę układu napędowego statku śródlądowego. Wskazano metody określania parametrów pracy układu napędowego, metody wyznaczania oporu oraz współczynników oddziaływania. Referat ma charakter poglądowy.

EN

The parameters of the propulsion system depends on the generated pressure and the resistance necessary to overcome produced by the unit. The water resistance depends on the navigation conditions on the waterway. The paper presents the influence of navigation conditions on the work conditions of the propulsion system of ship. The methods for determining the parameters of the drive system, the method of determination of resistance and impact factors were mentioned.

3

Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics. Part II. Influence of hull form modification on wake current behind the ship

Abramowski T., Szelangiewicz T.

Polish Maritime Research

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2010

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nr 1

3-9

EN

After signing ship building contract shipyard’s design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of three parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.

4

Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics. Part I. Influence of hull form modification on ship resistance characteristics

Szelangiewicz T., Abramowski T.

Polish Maritime Research

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2009

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nr 4

3-8

EN

After signing ship building contract shipyard’s design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of 3 parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.

5

Unsteady loads evaluation for a wind turbine rotor

Chkir S., Dobrev I., Kuszla P., Massouh F.

Diagnostyka

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2009

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nr 4(52)

17-22

EN

This paper presents a method for calculating the flow around a wind turbine rotor. The real flow is replaced by a free stream past a vortex model of the rotor. This model consists of lifting vortex lines which replace the blades and a trailing free vorticity. The vorticity shed from the blade is concentrated in two vortices issued from tip and root. To compute the unsteady forces exerted on the rotor, a free wake method is used. The evolution of the wake is obtained by tracking the markers representing the vortices issued from the blade tips and roots. To solve the wake governing equation and to obtain the marker positions, a time-marching method is applied and the solution is obtained by a second order predictor-corrector scheme. To validate the proposed method a comparison is made with experimental data obtained in the case of a model of wind turbine where the flow field immediately behind the rotor is measured by means of PIV. It is shown that the numerical simulation captures correctly the near wake development. The comparison shows satisfactory accuracy for the velocity field downstream of the rotor.

6

Obliczanie strumienia nadążającego statków śródlądowych

Kulczyk J., Zieliński A.

Systems : journal of transdisciplinary systems science

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2002

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Vol. 7, No. 1 sp.

322-330

PL

W pracy przedstawiono problematykę wyznaczania wartości współczynnika strumienia nadążającego statku w płaszczyźnie pracy pędnika. W rozpatrywanych modelach obliczeniowych w różny sposób określane były wartości współczynnika oporu tarcia statku oraz przestrzenność pola prędkości wokół kadłuba. W szczególności uwzględniono wpływ zanurzenia statku i prędkości prądu omywającego kadłub, co jest istotne w przypadku statków śródlądowych pływających po drogach wodnych o małych głębokościach. Otrzymane przykładowe wyniki zestawiono z dostępnymi danymi doświadczalnymi.

EN

The problem of determination of wake fraction in propeller disk is presented in this paper. In considered computational models the values of frictional resistance and velocity distribution around the hull were determined with application of various methods. In particular ship draught and stream velocity were considered because of their importance in the case of inland navigation vessels sailing in shallow waters. Example results obtained from calculations have been compared to available experimental data.

7

Application of hot-film sensors in analysis of wake induced boundary layer

Elsner W., Wysocki M., Sobczyk A.

Turbulence : international journal

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2000

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Vol. 6-7

175-186

EN

The paper presents an experimental analysis of the development of the unsteady boundary layer on a stator turbine blade. Upstream rotor wakes were generated by the rotating wheel of cylindrical rods. During the experiment three different cases with various wake-passing frequencies were tested and the boundary layer has been investigated with the use of surface mounted hot-films gauges. Analysis of the wall shear stresses presented in the paper reveals the high receptivity of boundary layer to periodical disturbances, which was documented among the others by the shift of laminar--turbulent transition zone from the region close to trailing edge upstream the flow.