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Transformacja systemu elektroenergetycznego w Niemczech: Energiewende – quo vadis?

Styczyński Z., Komarnicki P., Stoetzer M.

Energetyka – Społeczeństwo – Polityka

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2016

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nr 1(3)

31--49

EN

This article aims to answer the question on how proceeded and proceeds the transformation of the power system in Germany, and whether it will end with the expected success. The authors for many years have been actively participating in the work on the energy system transformation in Germany (some of them for more than 25 years) and share here their personal observations made on the background of the development of regional and global (Germany-wide) transformation known as Energiewende. As such, this study does not pretend, however, to be recognized as a comprehensive study of the Energiewende issues.

2

Identification of ship propeller torsional vibrations

Rosłanowski J.

Journal of KONES

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2015

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Vol. 22, No. 2

177--184

EN

The article presents identification methods of ship propeller torsional vibrations in dimensional space and ways for their dumping. Propeller torsional vibrations are caused by static, dynamic and hydrodynamic unbalance of propeller itself and its operation in non-uniform velocity field of ship hull. The propeller working in uneven velocity field of the hull creates cyclic thrust forces, peripheral vibrations of shaft as well as flexural and torsional load of propeller shaft. Vibrations cause additional thrust load on shaft bearings and shaft bending moment. Vibrations of ship hull, particularly its stern section cause variation of pressure field created by propeller. Amplitude of particular parts of the hull comes from the action of cyclic forces created by working ship propeller. They can be very large. Therefore, the ways to reduce vibrations caused by running propeller are very important. Given in the article methods of vibration dumping calculations conduct to determination of vibration dumping coefficients. Calculation results are comparable to measuring results in spite of fact they were determined under assumption of different velocity fields of water flowing through propeller circle. Amplitudes of vibrations depend on number of propeller blades and pulsate with the basic frequency equal to product of the rotational speed and number of blades. Causes of such vibrations and additional load of vessel stern are described in the article. An attention was paid to assure the greatest possible uniformity of velocity field by adequate design of stern shape and accessories. The ways to reduce torsional vibrations of propeller by the appropriate selection of blades number and their accurately machining are also given in the article.

3

Operation of diesel engine in direct ship propulsion

Rosłanowski J., Charchalis A.

Journal of KONES

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2011

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Vol. 18, No. 4

413-420

EN

In the paper an identification of low speed diesel engine operation in direct propulsion plant equipped with fixed pitch propeller during ship manoeuvring. It was starting of engine and gathering speed of ship. Analysis of engine operation was based on changes of engine torque and time of ship bring up to speed. Operation of reciprocating internal combustion engine consists in converting the supplied fuel energy and delivering it to ship propeller. This condition implicates converting different amounts of energy in different time. The main attention was given to operation of engine caused by crank pin forces in wide range of revolutions and their influence on mechanical load of ship propulsion plant. The torque is the major component determining the engine load. As a matter of fact its mean value is low, but a passing torque can be four times higher than the rated torque. The second important component of propulsion engine operation is the time of ship acceleration from one speed to another. It determines dynamic properties of the ship describing its reductional feature. This time is determined in dependence on other parameters characterizing operation of ship propulsion plant and ship motion by means of dimensional analysis. These parameters were regarded as dimension quantities of three-dimensional space. Thus the three independent in dimension parameters can be noted in digital form in dimensional functions. The knowledge of operation parameters of ship propulsion plant and the knowledge of ship motion dynamics makes possible rational manoeuvring. It increases safety of ship motion and failure-free operation of ship propulsion engine. The proper operation of engine requires delivery to the propeller such amount of energy, which ensure the motion of ship with required speed in given sailing conditions.

4

Parametric functions of ship propulsion engine operation

Roslanowski J.

Journal of KONES

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2010

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Vol. 17, No. 4

407-413

EN

The following article presents the method of determining the ship 's propulsion engine operation basing on the engines work parameters by means of dimensional analysis. The operation of engine is considered as effective energy transfer to ship propeller in the form of work during its operation. According to Girtler engine operation can be considered as, a new physical quantity of dimension Joul multiplied by second [2, 3J. A random type of combustion in engine cylinders makes possible to deal with engine operation as a random variable vectors in the Hilbert space isomorphic with dimension space. The analysis of stochastic engine workprocess is alternatively used as a set of determinist time functions by means dimension analysis. Parametric functions of engine work were determined on the basis of algebraic analysis scheme designed by S. Drobot. This scheme makes possible to control the correctness of conclusion rules regarding mathematics in digital functions describing operation of ship propulsion engine. Additionally the parametric form of function makes possible to investigate the influence of function parameters on correctness of engine operation. It makes possible to forecast the engine operation i given sailing conditions and to estimate steerability of ship during the voyage. It improves the safety of ship operation propelled by single engine propulsion plant.