虽然不确定度在测量领域已获得广泛应用，然而由于实验流体动力学原理和方法的复杂性，其应用还不成熟。当前的不确定度评定方法，是以国际不确定度评定指南GUM(Guide to the Expression of Uncertainty in Measure)为标准，然而，指南...虽然不确定度在测量领域已获得广泛应用，然而由于实验流体动力学原理和方法的复杂性，其应用还不成熟。当前的不确定度评定方法，是以国际不确定度评定指南GUM(Guide to the Expression of Uncertainty in Measure)为标准，然而，指南“GUM”只是给出了评定与表述不确定度的一般规则，并不是详尽的技术规范和说明，而且并不讨论所评定的不确定度如何运用于某种目的。因此，根据“指南GUM”制定某些专业标准是必要的。然而如何把“指南GUM”和实验流体动力学有机的结合，给出合理评定试验结果的不确定度是当前困难所在。本文以现有的研究为基础，详细分析了当前不确定度评定方法和实验流体动力学的特点，给出二者结合的方法，以期为建立在实验流体动力学中的不确定度评定标准提供参考。展开更多
Chebyshev polynomial is widely used in many fields, and used usually as function approximation in numerical calculation. In this paper, Chebyshev polynomial expression of the propeller properties across four quadrants...Chebyshev polynomial is widely used in many fields, and used usually as function approximation in numerical calculation. In this paper, Chebyshev polynomial expression of the propeller properties across four quadrants is given at first, then the expression of Chebyshev polynomial is transformed to ordinary polynomial for the need of simulation of propeller dynamics. On the basis of it, the dynamical models of propeller across four quadrants are given. The simulation results show the efficiency of mathematical model.展开更多
This study investigates the resistance of a transport ship navigating in level ice by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid car...This study investigates the resistance of a transport ship navigating in level ice by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid carriage using a one-directional load cell and then towed through an ice sheet at different speeds. We observed the ice-breaking process at different parts of the ship and motion of the ice floes and measured the resistances under different speeds to determine the relationship between the ice-breaking process and ice resistance. The bending failure at the shoulder area was found to cause maximum resistance. Furthermore, we introduced the analytical method of Lindqvist （1989） for estimating ice resistance and then compared these calculated results with those from our model tests. The results indicate that the calculated total resistances are higher than those we determined in the model tests.展开更多
The effects ofpH, dissolved ion content and relative water velocity on the release rate of an antifouling agent, cuprous oxide, from ships＇ hull paint have been investigated by rotating cylinder tests. Additionally, ...The effects ofpH, dissolved ion content and relative water velocity on the release rate of an antifouling agent, cuprous oxide, from ships＇ hull paint have been investigated by rotating cylinder tests. Additionally, test paint panels were attached to a vessel and recovered after a certain period of voyage for the validation of the laboratory tests. In the initial period, the release rates are influenced by pH, dissolved ion content and water velocity, but once after a certain period of test, those effects become less significant. These phenomena can be explained when the paint film is fresh, the rate is controlled by chemical reaction, the surface and/or diffusion layer in the water phase governs the rate. After the antifouling substance in the paint film leached out from the near-surface region, a diffused layer （leached layer）, that has little antifouling agent remained, is formed at the surface of the coating, and the diffusion in that layer can be a rate-determining process. The development of the leached layer is affected by a balance between the leaching rate of the antifouling ingredient and paint resin determined by the chemical properties and speed of the water. Thus, the leaching rates of antifouling agents are affected by the history of the paint in the water.展开更多
The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in...The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in the measurement of heel angle. Nowadays, digital inclinometers are available, but they are expensive. In this study, the use of a smartphone application is presented for ship inclination and rolling-period tests. The idea consists of using accelerometer and gyroscope sensors built into the current smartphones for the measurements. Therefore, some experiments are carried out on an example trawler model to exhibit the uses and advantages of this method. The obtained results are in good agreement with those provided from the pendulum method and natural roll-period test. This application is new, easy, and more accurately assesses metacentric height during the inclining and rolling-period tests.展开更多
To protect environment, and to comply with the IMO＇s （International Maritime Organization） newest regulations about ship＇s SOx emission. This thesis illustrates a closed recycling absorb system based on NaOH solut...To protect environment, and to comply with the IMO＇s （International Maritime Organization） newest regulations about ship＇s SOx emission. This thesis illustrates a closed recycling absorb system based on NaOH solution recycling particularly for SOx onboard. The goal is to use NaOH solution to absorb SOx, and reduce the damage the ships made towards environment. The thesis analyzes the main features that could influence the absorption of SOx on board, and the precipitations during the experiment. To reveal that NaOH solution is very highly effective and economic in absorption of SOx on ships by this experiment, and to set a theoretical basic fundamental for future application of alkali solution recycling absorption system for SOx.展开更多
This paper presents experimental and numerical studies on spray painting processes by using airless spray guns for ship painting. A computational fluid dynamics code was applied to calculate the flow field and the dro...This paper presents experimental and numerical studies on spray painting processes by using airless spray guns for ship painting. A computational fluid dynamics code was applied to calculate the flow field and the droplet trajectories. Droplet size distributions and droplet velocities as necessary inlet characteristics for the simulations were experimentally obtained using a Spraytec Fraunhofer type particle sizer and laser-Doppler anemometry. Effects of shoreline winds and painting distance on the transfer efficiency and on the paint film thickness distributions on the target were numerically studied.展开更多
文摘虽然不确定度在测量领域已获得广泛应用，然而由于实验流体动力学原理和方法的复杂性，其应用还不成熟。当前的不确定度评定方法，是以国际不确定度评定指南GUM(Guide to the Expression of Uncertainty in Measure)为标准，然而，指南“GUM”只是给出了评定与表述不确定度的一般规则，并不是详尽的技术规范和说明，而且并不讨论所评定的不确定度如何运用于某种目的。因此，根据“指南GUM”制定某些专业标准是必要的。然而如何把“指南GUM”和实验流体动力学有机的结合，给出合理评定试验结果的不确定度是当前困难所在。本文以现有的研究为基础，详细分析了当前不确定度评定方法和实验流体动力学的特点，给出二者结合的方法，以期为建立在实验流体动力学中的不确定度评定标准提供参考。
文摘Chebyshev polynomial is widely used in many fields, and used usually as function approximation in numerical calculation. In this paper, Chebyshev polynomial expression of the propeller properties across four quadrants is given at first, then the expression of Chebyshev polynomial is transformed to ordinary polynomial for the need of simulation of propeller dynamics. On the basis of it, the dynamical models of propeller across four quadrants are given. The simulation results show the efficiency of mathematical model.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 51179123 and 51279131
文摘This study investigates the resistance of a transport ship navigating in level ice by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid carriage using a one-directional load cell and then towed through an ice sheet at different speeds. We observed the ice-breaking process at different parts of the ship and motion of the ice floes and measured the resistances under different speeds to determine the relationship between the ice-breaking process and ice resistance. The bending failure at the shoulder area was found to cause maximum resistance. Furthermore, we introduced the analytical method of Lindqvist （1989） for estimating ice resistance and then compared these calculated results with those from our model tests. The results indicate that the calculated total resistances are higher than those we determined in the model tests.
文摘The effects ofpH, dissolved ion content and relative water velocity on the release rate of an antifouling agent, cuprous oxide, from ships＇ hull paint have been investigated by rotating cylinder tests. Additionally, test paint panels were attached to a vessel and recovered after a certain period of voyage for the validation of the laboratory tests. In the initial period, the release rates are influenced by pH, dissolved ion content and water velocity, but once after a certain period of test, those effects become less significant. These phenomena can be explained when the paint film is fresh, the rate is controlled by chemical reaction, the surface and/or diffusion layer in the water phase governs the rate. After the antifouling substance in the paint film leached out from the near-surface region, a diffused layer （leached layer）, that has little antifouling agent remained, is formed at the surface of the coating, and the diffusion in that layer can be a rate-determining process. The development of the leached layer is affected by a balance between the leaching rate of the antifouling ingredient and paint resin determined by the chemical properties and speed of the water. Thus, the leaching rates of antifouling agents are affected by the history of the paint in the water.
文摘The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in the measurement of heel angle. Nowadays, digital inclinometers are available, but they are expensive. In this study, the use of a smartphone application is presented for ship inclination and rolling-period tests. The idea consists of using accelerometer and gyroscope sensors built into the current smartphones for the measurements. Therefore, some experiments are carried out on an example trawler model to exhibit the uses and advantages of this method. The obtained results are in good agreement with those provided from the pendulum method and natural roll-period test. This application is new, easy, and more accurately assesses metacentric height during the inclining and rolling-period tests.
文摘To protect environment, and to comply with the IMO＇s （International Maritime Organization） newest regulations about ship＇s SOx emission. This thesis illustrates a closed recycling absorb system based on NaOH solution recycling particularly for SOx onboard. The goal is to use NaOH solution to absorb SOx, and reduce the damage the ships made towards environment. The thesis analyzes the main features that could influence the absorption of SOx on board, and the precipitations during the experiment. To reveal that NaOH solution is very highly effective and economic in absorption of SOx on ships by this experiment, and to set a theoretical basic fundamental for future application of alkali solution recycling absorption system for SOx.
文摘This paper presents experimental and numerical studies on spray painting processes by using airless spray guns for ship painting. A computational fluid dynamics code was applied to calculate the flow field and the droplet trajectories. Droplet size distributions and droplet velocities as necessary inlet characteristics for the simulations were experimentally obtained using a Spraytec Fraunhofer type particle sizer and laser-Doppler anemometry. Effects of shoreline winds and painting distance on the transfer efficiency and on the paint film thickness distributions on the target were numerically studied.
