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EN
The paper covers basics of the vortex model used for propeller-stator systems. The outline of the design algorithm is given and the results of its application are shown. The designed propeller-stator system was the subject of model tests run at the CTO model basin and cavitation tunnel. Stator’s influence on the delivered power required by the propeller and its revolution rate has been examined by conducting self-propulsion tests with and without stator. The tests performed in the cavitation tunnel revealed only weak tip vortex cavitation on the propeller. No cavitation was observed on the stator at the design point. A wide range of the performed tests allowed the authors to identify details of the developed theory which will require further improvement.
2
Content available Drag and Torque on Locked Screw Propeller
EN
Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades). The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.
EN
The paper presents the summary of results of the numerical analysis of the unsteady propeller performance in the non-uniform ship wake modified by the different wake improvement devices. This analysis is performed using the lifting surface program DUNCAN for unsteady propeller analysis. The object of the analysis is a 7000 ton chemical tanker, for which four different types of the wake improvement devices have been designed: two vortex generators, a pre-swirl stator, and a boundary layer alignment device. These produced five different cases of the ship wake structure: the original hull and hull equipped alternatively with four wake improvement devices. Two different propellers were analyzed in these five wake fields, one being the original reference propeller P0 and the other - a specially designed, optimized propeller P3. The analyzed parameters were the pictures of unsteady cavitation on propeller blades, harmonics of pressure pulses generated by the cavitating propellers in the selected points and the fluctuating bearing forces on the propeller shaft. Some of the calculated cavitation phenomena were confronted with the experimental. The objective of the calculations was to demonstrate the differences in the calculated unsteady propeller performance resulting from the application of different wake improvement devices. The analysis and discussion of the results, together with the appropriate conclusions, are included in the paper.
EN
The article presents the results of experimental and numerical investigation of propeller scale effects, undertaken in co-operation of the Hamburg Ship Model Basin (HSVA), Germany, and Ship Design and Research Centre (CTO SA), Poland. The objective of the investigation was to test the adequacy of the methods currently used to account for the propeller scale effect and to develop possible improvement of the methods. HSVA has conducted model experiments in the large cavitation tunnel together with panel method and CFD calculations. CTO SA has performed model experiments in the towing tank, together with lifting surface and CFD calculations. Both institutions have suggested different new approaches to the problem and different new procedures to account for the propeller scale effects. In the article the procedures are presented together with the description of the underlying experimental and theoretical research.
5
Content available remote An overview of the selected results of the European Union Project EFFORT
EN
The European-Union EFFORT (European Full-Scale Flow Research and Technology) project focuses on validating and introducing innovative Computational Fluid Dynamics (CFD) prediction methods for the performance of the ship/propeller combination at the full scale, instead of the usual model scale. Within the project existing CFD codes have been extended, extensive full scale and model-scale (PIV) flow measurements have been conducted, and validation of the CFD predictions has been carried out. In this paper an overview of the EFFORT project results is given and the innovations that have been implemented by EFFORT consortium group are shown. The model scale PIV expcriments that have been carried out on two vessels are also discussed. In the papcr there are shown some of the validation rcsults based on these experiments. Finally there are selected examples of the calculations that have been carried oul by CTO S.A. in which the validated CFD computations have been used as a design tool replacing the model tests which are normally carried out.
PL
Celem europejskiego projektu badawczego o akronimie EFFORT pt.: "Europejskie badania i technika pomiaru opływu okrętu w pełnej skali", był rozwój metod Numerycznej Mechaniki Płynów (CFD) poprzez stworzenie unikalnej bazy wyników pomiarów, w skali naturalnej (rzeczywistej skali statku) podczas rejsów na otwartym morzu i na modelach badanych w basenach holowniczych. W ramach projektu przeprowadzono pomiary parametrów opływu kadłubów, w szczególności pól prędkości, (w skali pełnej, techniką laserową LDV) i równoważne, w skali modelowej (techniką PIV oraz klasyczną sondami Pilota, dla dwu statków: szkolno - badawczego statku Akademii Morskiej w Szczecinie - Nawigator XXI o długości Lpp = 54.13 m, oraz pogłębiarki oceanicznej IHC - Uilenspiegel, o długości Lpp = 126.0 m. Praca omawia sam projekt badawczy oraz prezentuje nową technikę pomiarową PIV. Wyniki pomiarów posłużyły jako podstawa do oceny wyników obliczeń opływu statków za pomocą systemów rozwijanych w ramach projektu.
PL
Artykuł jest próbą określenia możliwości wykorzystania struktur samoorganizujących się w procesach przygotowania powierzchni przed cynkowaniem zanurzeniowym. Przedstawiono wyniki badań wstępnych wytworzenia powłok cynkowych po procesie przygotowania powierzchni w roztworach na bazie struktur samoorganizujących się. Stwierdzono, że zaproponowany sposób przygotowania powierzchni zapewnia otrzymanie poprawnych powłok cynkowych na żeliwie ciągliwym, sferoidalnym oraz stali po procesie gorącego walcowania. Struktury przekroju poprzecznego otrzymanych powłok nie odbiegają morfologią i składem fazowym od powłok cynkowych otrzymywanych po tradycyjnym przygotowaniu powierzchni.
EN
The article is an attempt to identify the possibilities of using self-organising structure in the processes of surface preparation for hot-dip galvanising. It presents the results of preliminary tests of zinc coats produced after the process of surface preparation in solutions on the basis of self-organising structures. The proposed surface preparation method has been found to assure obtaining of correct zinc coats on malleable cast iron, ductile cast iron and hot rolled steel. The cross-section structures of obtained coats do not differ in morphology and phase composition from zinc coats obtained after traditional surface preparation.
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