This paper has predicted the range and volume of unsteady sheet cavitation of a propeller by using the surface panel method. The linearization in cavity thickness is adopted to reduce the computing time and storage sp...This paper has predicted the range and volume of unsteady sheet cavitation of a propeller by using the surface panel method. The linearization in cavity thickness is adopted to reduce the computing time and storage space. The iteration scheme between chordwise strips has been used because the range and volume of cavitation are both unknown. The propeller cavitation range determined by the calculation method presented in this paper agrees with the observation results of cavity image at cavitation tunnel very well, and this proves the practicability of the method.展开更多
作为感官评价仪器的"评价员/评价小组"是获得可靠感官分析数据的关键,其性能表现评估技术是有效管理该仪器的重要手段。本文将信度与效度作为该"仪器"的评估指标,发现21世纪以后该类研究进入高峰期,其超过85%的研...作为感官评价仪器的"评价员/评价小组"是获得可靠感官分析数据的关键,其性能表现评估技术是有效管理该仪器的重要手段。本文将信度与效度作为该"仪器"的评估指标,发现21世纪以后该类研究进入高峰期,其超过85%的研究成果发表于Food Quality and Preference与Journal of Sensory Studies这两个感官研究类权威杂志中,其中欧美国家在此技术中占主导地位。透过技术内容发现,基于定量描述能力的评价小组及成员性能表现评估技术研究频繁并趋于成熟,技术手段重点采用单参数或多参数方差分析、多元统计方法(主成分分析、广义普罗克分析等),涌现了以PanelCheck、Compusense Five等为代表的评估软件,同时国际标准化组织和美国材料与试验协会机构也进入相关标准研制阶段。而有关差别与排序的评估技术研究相对缺乏。本文提出性能评估所用样品性质及数量、性能评估所用数据表现形式、性能评估感官实验设计要求、性能评估期望值及置信区间、性能评估所用感官分析方法选择、性能评估的数学统计方法选择等关键要素将成为该领域未来努力的方向,并有助于形成统一的、系统的感官分析评价小组及成员表现评估技术规范。展开更多
The unsteady sheet cavitation of podded propeller was predicted by using a surface panel method. The interaction between propeller and pod was treated with the iterative calculation of induced velocity potential, and ...The unsteady sheet cavitation of podded propeller was predicted by using a surface panel method. The interaction between propeller and pod was treated with the iterative calculation of induced velocity potential, and the method of induced velocity potential can save a great deal of storage and computation time compared to the method of induced velocity. The induced velocity potential of unit singularity on every pod panel to every key blade panel and of unit singularity on every key blade panel and its wake panel to every pod panel were calculated when the key blade is at every angle position. Based on the wake model of the conventional single propeller, a new wake model of podded propeller was constructed. The propeller is analyzed only on the key blade in order to save computation time and memory space. The method can be used to calculate the hydrodynamics performance and cavitation of propeller in uniform and non-uniform inflows. It can give the unsteady force and cavitation shape of propeller. The propeller cavitation range determined by the present method agrees with the observation results of cavity image given in cavitation tunnel well, and this proves the practicability of the method.展开更多
文摘This paper has predicted the range and volume of unsteady sheet cavitation of a propeller by using the surface panel method. The linearization in cavity thickness is adopted to reduce the computing time and storage space. The iteration scheme between chordwise strips has been used because the range and volume of cavitation are both unknown. The propeller cavitation range determined by the calculation method presented in this paper agrees with the observation results of cavity image at cavitation tunnel very well, and this proves the practicability of the method.
文摘作为感官评价仪器的"评价员/评价小组"是获得可靠感官分析数据的关键,其性能表现评估技术是有效管理该仪器的重要手段。本文将信度与效度作为该"仪器"的评估指标,发现21世纪以后该类研究进入高峰期,其超过85%的研究成果发表于Food Quality and Preference与Journal of Sensory Studies这两个感官研究类权威杂志中,其中欧美国家在此技术中占主导地位。透过技术内容发现,基于定量描述能力的评价小组及成员性能表现评估技术研究频繁并趋于成熟,技术手段重点采用单参数或多参数方差分析、多元统计方法(主成分分析、广义普罗克分析等),涌现了以PanelCheck、Compusense Five等为代表的评估软件,同时国际标准化组织和美国材料与试验协会机构也进入相关标准研制阶段。而有关差别与排序的评估技术研究相对缺乏。本文提出性能评估所用样品性质及数量、性能评估所用数据表现形式、性能评估感官实验设计要求、性能评估期望值及置信区间、性能评估所用感官分析方法选择、性能评估的数学统计方法选择等关键要素将成为该领域未来努力的方向,并有助于形成统一的、系统的感官分析评价小组及成员表现评估技术规范。
基金Supported by the China Postdoctoral Science Foundation(Grant No.2012M512133)the National Natural Science Foundation of China(Grant NO.41176074)the Fundamental Research Funds for the Central University(Grant NO.T013513015)
基金Project supported by the Research Foundation of the Ministry of Education Key Laboratory of High Speed Ship Engineering(Grant No. HSSE0803).
文摘The unsteady sheet cavitation of podded propeller was predicted by using a surface panel method. The interaction between propeller and pod was treated with the iterative calculation of induced velocity potential, and the method of induced velocity potential can save a great deal of storage and computation time compared to the method of induced velocity. The induced velocity potential of unit singularity on every pod panel to every key blade panel and of unit singularity on every key blade panel and its wake panel to every pod panel were calculated when the key blade is at every angle position. Based on the wake model of the conventional single propeller, a new wake model of podded propeller was constructed. The propeller is analyzed only on the key blade in order to save computation time and memory space. The method can be used to calculate the hydrodynamics performance and cavitation of propeller in uniform and non-uniform inflows. It can give the unsteady force and cavitation shape of propeller. The propeller cavitation range determined by the present method agrees with the observation results of cavity image given in cavitation tunnel well, and this proves the practicability of the method.
