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1

Waterjet propulsion of small-draught inland waterways ships

Domachowski Z., Próchnicki W.

Polish Maritime Research

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2006

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S 2

66-71

EN

This paper presents some aspects of ship waterjet propulsion. Advantages and limitations of its applicability are discussed. Also, possible use of waterjet propeller to move a small-draught inland waterways ship, is considered .

2

A proposal of ship gas-turbine driven waterjet propulsion - preliminary considerations

Próchnicki W.

Polish Maritime Research

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2004

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S 1

79-82

EN

In the paper are presented preliminary considerations concerning the efficiency of waterjet ship propulsion system, as well as the calculation of main dimensions of waterjet channel. The friction and momentum losses of the flow channel have been roughly estimated by using Fliegner s equations. An important conclusion is confirmed that the summary losses are inversely proportional to square of ship velocity (~1/u2). On the other hand the ship propulsion power is directly proportional to third power of ship velocity (~u3). Therefore to minimize ship s hull resistance, hulls of water jet-driven ships ought to be of a great slenderness - e.g. L/B = 15, stabilized by sponsons, or of semi-swath hydrofoil-supported construction.

3

Impact of sea wave stochastic characteristics on ship propulsion control system design

Domachowski Z., Próchnicki W., Dzida M., Piwowarski M.

Marine Technology Transactions. Technika Morska

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2004

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Vol. 15

393-409

EN

A sea wave resistance to the ship motion is of stochastic nature. Therefore any design and optimization of ship propulsion control system requires a knowledge of wave resistance stochastic characteristics. Sea waving is usually considered as the most important disturbance affecting the dynamics of ship propulsion unit. In rough sea conditions it causes high amplitudes of torsional torques which lead to torsional vibrations of the elements of propulsion system. Limitation of tordional stresses is vitally important in order to avoid damage or even fracture of the propulsion system components. Torsional stresses involve the whole shaft system of the ship's propulsion engineering: engine crank shaft, intermediate shafts, propeller and propeller shaft, engine running gear, flywheel, and where appropriate reduction gearing, flexible couplings, clutches, and electric generator shaft. For a cost effective ship propulsion plant with the best counter measures against torsional stresses, it is important that torsional vibration aspects areconsidered at the earliest stage possible in the ship design process. In such circumstances the role of propulsion plant controller can be significant. With regard to sea wave stochastic characteristics a method of design and optimization of ship propulsion controller architecture and parameters has been discussed. Several simulations have been carried out based on sea wave stochastic characteristics. Some different sea areas in the world have been taken into account, and four seasons of year. The ship propulsion system bas been treated as a multidimensional control system of angular velocity od diesel engine. The dynamic processes of the propulsion system have been determined as a response to the disturbance caused by the ship propeller.

PL

Siła oporu statku jest procesem stochastycznym. Z tego powodu projektowanie i ewentualna optymalizacja układu sterowania napędu statku wymaga znajomości charakterystyk statycznych fali morskiej. Oddziaływanie zakłócające fali morskiej wywołuje, między innymi, zmiany momentów skręcających w elementach zespołu napędowego statku. Jest niezbędne ograniczenie momentów skręcających i wywołanych nimi drgań skrętnych, w celu uniknięcia ewentualnych uszkodzeń w zespole napędowym. Naprężenia skrętne występują w całym zespole napędowym statku: w walw silnika, wałach pośrednich, w wale pędnika, w sprzęgłach, przekładni. W tych warunkach dobór parametrów regulatora napędu statku umoże okazać się istotny. Wskazano sposoby doboru transmisji regulatora w warunkach stochastycznych. Wybrano do rozważań 8 rejonów morskich w 4 porach roku. Określono w nich gęstość widmową amplitudy fali morskiej. Założono, regulator typu proporcjonalno-całkująco-różniczkujący. Dla wybranego typu statku wykonane badania symulacyjne odnoszą się do wybranych rejonów mórz i pór roku. Okazuje się, że dobierając zarówno współczynnik wzmocnienia regulatora jak i stałą całkowania, można minimalizować wartość wariancji, na przykład, momentów skręcających w wybranych przekrojach zespołu napędowego lub prędkości kątowych wału. Przedstawiono przykłady tego rodzaju optymalizacji regulatora ze wzgledu na współczynnik wzmocnienia.

4

Influence of gas parameters alternation on the form of gas-flow-impact appearing in long transportation pipelines

Próchnicki W., Dzida M.

Transactions of the Institute of Fluid-Flow Machinery

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2003

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nr 114

77-90

EN

In the case of the gate-valve cut-off, in a very long transmission pipelines, considerable pressure overshoots are observed accompanying the gas flow impacts, caused as well by shock wave as by reflected one. The main factor, influencing the shock wave amplitude, is the velocity of gate-valve closing, determined by the servomotor-time-constant Ti. Because of possible variations of chemical constitution of gas transported through the pipeline - which renders physical, chemical and thermodynamic properties changes, it is necessary to examine theirs degree of influence on the processes of dynamic impact.

5

Hydraulic impact in a long gas-pipelines

Próchnicki W., Dzida M.

Marine Technology Transactions. Technika Morska

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2002

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Vol. 13

141-149