典型护卫舰飞行甲板空气流场数值模拟

为研究护卫舰飞行甲板气流场特性,获得较高精度的流场数据用于飞行仿真,利用FLUENT对孤立简化护卫舰进行数值模拟.通过合理的网格划分以及对求解方法的验证,讨论了不同网格形式及雷诺数对计算结果的影响,分析了不同湍流模型对于舰船流场计算适用性,准确捕捉了飞行甲板处涡脱落频谱特征,提高了舰船气流场计算数据精确度.研究结果表明,对于一些精确度要求较高的舰船流场计算,ILES模型较为合适.     

当代水面战舰的主动力装置

本文介绍了现役航空母舰、巡洋舰、驱逐舰和护卫舰主动力装置的装舰情况。统计分析了最近三十年来上述战舰各种发动机的装舰使用情况,指出了各型战舰主动力装置的发展趋势     

不同护卫舰船型飞行甲板气流场特征研究

为了研究舰船气流场特征,对简化船型SFS1和SFS2以及实体护卫舰船型进行数值模拟,与风洞实验数据对比验证,分析了飞行甲板周围气流场特征．通过对SFS1船型的计算,得到了舰船中心表面压力系数的分布,发现涡在机库顶端分离、脱落并且再附着于飞行甲板,验证了飞行甲板表面马蹄涡的存在．算例结果表明护卫舰船体结构对空气的阻滞作用是涡分离和脱落的重要驱动力．对于实体护卫舰船型分别计算了0°和右舷30°风向角时的气流场工况,分析发现机库结构的形状和尺寸会影响飞行甲板周围涡旋的强度和位置．在0°风向角时,机库门敞开有助于改善飞行甲板的气流场状况．     

舰船尾部结构对直升机操作区流场的影响

为研究舰船尾部结构对流场环境的影响,以典型护卫舰简化模型SFS1为对象,选用通用软件ANSYS ICEM划分结构化网格并用ANSYS FLUENT标准k-ε湍流模型模拟了机库门开闭不同状态、不同机库高度及不同飞行甲板长度等特征结构的变化对直升机操作区气流场的影响.通过分析流场中的速度、压力等物理量,对比了不同工况下的流场环境.对比结果显示,机库高度越低、飞行甲板长度越长舰载机操作区的流场环境越好,机库门半开时流场环境较机库门关闭和全开状态时差,但是机库门关闭和全开两种状态相比没有明显的优劣之分.这可为在役舰船的改造和再建舰船的优化设计提供理论依据和数据支持,进而有效改善舰载机起降时的流场环境,提高海军指挥直升机进行安全着舰的能力.     

雷达哨舰在编队防空中的使用研究

论述了雷达哨舰的使用原则,对雷达哨舰的前出方位、前出距离、舰间距和所需哨舰的数量建立了数学模型,得出了编队防御中雷达哨舰使用的优化方案,以期为作战部队制定观察组织方案提供参考,具有一定的军事价值。     

Improvement of Fish-sauce Odor by Treatment with Bacteria Isolated from the Fish-sauce Mush (Moromi) Made from Frigate Mackerel

ABSTRACT: A bacterium, which was isolated from fish-sauce mush (moromi) of frigate mackerel and identified as Staphylococcus xylosus , could change notes of an odor in fish sauce made in Thailand. Volatile compounds of the fish sauce after incubation at 32 °C for 24 d with the cultured bacterium were analyzed by gas chromatogra-phy. Although the contents of 2-ethylpyridine and dimethyl trisulfide were reduced during the incubation, 4 volatile compounds, including 2-methylpronal, 2-methylbutanal, 2-pentanone, and 3-(methylthio)propanal, showed no significant quantity changes. On the other hand, although 3-methyl-1-butanol and 2,6-dimethylpyrazine were markedly increased, 3-methylbutanoic acid was slightly increased. As a result of sensory evaluation, fishy, sweaty, fecal, and rancid notes of the fish sauce treated with the bacterium were all weaker than those of the nontreated fish sauce. No changes were found with respect to burnt, cheesy, meaty, and ammoniacal notes between fish sauce treated with the bacterium and that without treatment. Taken together, the odor of fish sauce was much improved by treatment with the isolated bacterium.