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A laser Doppler velocimetry (LDV) phase sampling technique is developed and adopted for the analysis of the flow upstream
and behind a four-blade, highly skewed installed propeller in the case of a twin-screw ship model in a large circulating water
channel. The technique implemented allows the reconstruction of the 3D flow field as a function of propeller angle in transversal
planes located as close as possible to the blade trailing and leading edges. The main features of the propeller installation
are highlighted, as well as the strong and complex interaction of the propeller with the hull wake, especially in the brackets
region. The high level of detail and accuracy of the data acquired would be a powerful tool for the development and validation
of computational codes applied to this topic. 相似文献
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贯流风扇内部流场流动特征及流速分布的研究 总被引:1,自引:0,他引:1
通过激光幕及激光多普勒流速计(LDV)等先进实验手段,对目前家用、车用小型空调中所使用的贯风流风部流场进行了可视化及流速分布研究,得出了贯流风流内部流动随着叶轮片倾角及热交换器有无等条件变化而变化的规律。 相似文献
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DTMB P4119桨尾流场LDV测试 总被引:2,自引:1,他引:1
采用LDV测速系统,在大型空泡水筒中对均匀来流下的螺旋桨尾流场进行了测量。把测试点数据集合在一个圆盘面上进行宏观显示。试验测试了尾流场中尾涡结构,获得了尾流场中轴向、径向速度沿周向分布的周期性规律,分析了近梢部流场速度分布的双突跳结构。试验所获得的定量信息为螺旋桨尾流场复杂流动现象的揭示提供了帮助。 相似文献
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Vehicles are considered to be an important source of ammonia (NH3) and isocyanic acid (HNCO). HNCO and NH3 have been shown to be toxic compounds. Moreover, NH3 is also a precursor in the formation of atmospheric secondary aerosols. For that reason, real-time vehicular emissions from a series of Euro 5 and Euro 6 light-duty vehicles, including spark ignition (gasoline and flex-fuel), compression ignition (diesel) and a plug-in electric hybrid, were investigated at 23 and −7 °C over the new World harmonized Light-duty vehicle Test Cycle (WLTC) in the Vehicle Emission Laboratory at the European Commission Joint Research Centre Ispra, Italy. The median HNCO emissions obtained for the studied fleet over the WLTC were 1.4 mg km−1 at 23 °C and 6 mg km−1 at −7 °C. The fleet median NH3 emission factors were 10 mg km−1 and 21 mg km−1 at 23 and −7 °C, respectively. The obtained results show that even though three-way catalyst (TWC), selective catalytic reduction (SCR), and NOx storage catalyst (NSC) are effective systems to reduce NOx vehicular emissions, they also lead to considerable emissions of the byproducts NH3 and/or HNCO. It is also shown that diesel light-duty vehicles equipped with SCR can present NH3 emission factors as high as gasoline light-duty vehicles at both, 23 and −7 °C over the WLTC. Therefore, with the introduction in the market of this DeNOx technology, vehicular NH3 emissions will increase further. 相似文献
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