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.
During designing the ship its designer tends to obtain as high as possible efficiency of ship propulsion system. To this end on certain ships additional elements such as: nozzles, half-nozzles or ...suitably profiled fins attached to underwater part of ship's hull before screw propeller, are applied (sometimes they are intended for the mitigating of vibration resulting from operation of screw propeller). Another device which affects operation of screw propeller is streamline rudder capable of improving its efficiency (most of the transport ships is fitted with single screw propeller and streamline rudder placed behind it). In this paper the influence of streamline rudder on screw propeller efficiency has been examined with the use of numerical methods of fluid dynamics (CFD). The obtained results indicate a very favourable influence of the rudder on screw propeller efficiency. Research in this area is continued and its results concerning impact of particular geometrical parameters of rudder on screw propeller efficiency, will be presented in the future.
During designing the ship its designer tends to achieve as-high-as possible efficiency of ship's propulsion system. The greatest impact on the efficiency is introduced by ship's screw propeller whose ...efficiency depends not only on its geometry but also distribution of wake current velocity. To change wake current distribution and improve propeller efficiency an asymmetric form is usually applied to stern part of ship hull. This paper presents results of numerical analysis of wake current velocity distribution, performed by using a CFD method for a B 573 ship of symmetric stern and the same ship of an asymmetric stern. Next, the mean values of screw propeller efficiency in non-homogenous water velocity field were calculated for both the hull versions of B 573 ship.
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.
The sequence of events leading to the programmed cell death (PCD) induced by heavy metals in plants is still the object of extensive investigation. In this study we showed that roots of 3-day old ...yellow lupine (Lupinus luteus L.) seedlings exposed to cadmium (Cd, 89μM CdCl2) resulted in PCD starting from 24h of stress duration, which was evidenced by TUNEL-positive reaction. Cd-induced PCD was preceded by a relatively early burst of nitric oxide (NO) localized mainly in the root tips. Above changes were accompanied by the NADPH-oxidase-dependent superoxide anion (O2−) production. However, the concomitant high level of both NO and O2− at the 24thh of Cd exposure did not provoke an enhanced peroxynitrite formation. The treatment with the NADPH-oxidase inhibitor and NO-scavenger significantly reduced O2− and NO production, respectively, as well as diminished the pool of cells undergoing PCD. The obtained data indicate that boosted NO and O2− production is required for Cd-induced PCD in lupine roots. Moreover, we found that in roots of 14-day old lupine plants the NO-dependent Cd-induced PCD was correlated with the enhanced level of the post-stress signals in leaves, including distal NO cross-talk with hydrogen peroxide.
► Roots of yellow lupine exposed to Cd resulted in programmed cell death (PCD). ► Cd-induced PCD was preceded by NO production as well as was accompanied by NADPH-oxidase-dependent O2− accumulation. ► The concomitant high level of NO and O2− did not result in a significant peroxynitrite formation. ► PCD in roots was correlated with the enhanced level of the post-stress signals in leaves
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