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| 1 | Particle reconstruction of volumetric particle image velocimetry with the strategy of machine learning显示文摘Three-dimensional particle reconstruction with limited two-dimensional projections is an under-determined inverse problem that the exact solution is often difficult to be obtained.In general,approximate solutions can be obtained by iterative optimization methods.In the current work,a practical particle reconstruction method based on a convolutional neural network(CNN)with geometry-informed features is proposed.The proposed technique can refine the particle reconstruction from a very coarse initial guess of particle distribution that is generated by any traditional algebraic reconstruction technique(ART)based methods.Compared with available ART-based algorithms,the novel technique makes significant improvements in terms of reconstruction quality,robustness to noise,and at least an order of magnitude faster in the offline stage. | Qi Gao Shaowu Pan Hongping Wang Runjie Wei Jinjun Wang | 2021 | Advances in Aerodynamics2021，3，1： | 0 |
| 2 | Experimental and numerical investigations into flow features in an intake duct for the waterjet propulsion under mooring conditions显示文摘The waterjet propulsion is widely applied in the marine vessels over 30 knots,and the intake duct is considered as an essential component that strongly relates to the propulsion performance.This paper sheds light on the flow features inside an intake duct under mooring conditions by using the particle image velocimetry(PIV)technique with three-dimensional(3D)numerical simulations.The hydraulic loss gradually increase as the flow-rate increases.According to analyses via the Bernoulli equation,the hydraulic loss is composed of the frictional head loss(h_(f)~V^(1.75))and the local head loss(h_(j)~V^(2.0)).A recirculation region is observed near the duct lower wall with a high-velocity flow near the upper wall,and subsequently a shear flow presents in the horizontal straight pipe with an obvious velocity gradient.Three-dimensional simulations demonstrate that the vortex pair is very strong in the recirculation region and then it gradually decreases as the fluid flows downstream.With the flow-rate increasing,the non-uniformity at the duct outlet firstly increases to a peak and then slightly decreases,while the perpendicularity at the duct outlet dramatically decreases to a minimum and then increases.This work not only reveals some physics of the waterjet propulsion under mooring conditions,but also promotes its efficient operation. | Renfang Huang Ruizhi Zhang Yiwei Wang Xianwu Luo Lei Zhu | 2021 | Acta Mechanica Sinica2021，37，5： | 0 |
| 3 | 基于主动射流方法的椭圆水翼梢涡空化抑制研究显示文摘[目的]梢涡空化会产生压力波动和流动噪声,预测梢涡空化的初生和发展过程,了解其作用机理并加以抑制是船舶螺旋桨与旋转机械亟待解决的问题。[方法]以剖面为NACA 0012翼型的椭圆水翼为研究对象,基于IDDES湍流模型和Schnerr-Sauer空化模型,分别在全湿流和空泡流两种工况下对水翼梢涡及其空化现象进行模拟,分析水翼梢涡及其空化之间的相互作用特性。进一步,通过主动射流方法控制水翼梢涡空化,并对比两种开孔射流方式,即垂向射流和侧向射流的作用效果。[结果]以梢涡体积作为空泡抑制的判断标准,与无射流工况对比,垂向射流工况对空泡的抑制效果可达到8.09%;而在侧向射流工况下,射流对空泡的抑制效果更加明显,达到了10.47%。结果证明两种主动射流方式均可以有效抑制梢涡空化。[结论]通过机理分析发现,垂向射流会影响水翼梢涡入射流的流速及流向,提高梢涡湍动能的耗散项,从而降低水翼的梢涡强度;而在侧向射流工况下,射流则直接作用于梢涡,所携带的能量极大地破坏了水翼的梢涡结构,从而大大降低了梢涡空化现象的产生。 | 刘亢 曹留帅 万德成 | 2023 | 中国舰船研究2023，18，4： | 0 |
| 4 | 主动射流抑制云空化及流致噪声的研究显示文摘云空化及其诱导噪声对螺旋桨、船下附体等海洋装备的水动力性能有不利的影响。针对NACA66水翼,提出了在吸力面上布设单排射流孔向流场中注入流体,以期改善流场。采用密度修正的k-ε湍流模型和ZGB空化模型对水翼的云空化非定常过程进行数值模拟,数值计算结果与试验观测吻合较好。研究结果表明:在相同的云空化条件下,主动射流有效地抑制了空化的发生、发展和脱落,并对水翼近场噪声的降低具有积极影响。与原始水翼相比,射流水翼云空化团的脱落频率降低了41.2%,在一个周期内的平均空泡体积减少了72.9%。采用主动射流后,低频段的噪声峰值得到大幅削弱,中、高频段的噪声普遍降低。监测点的总声压级平均降低了16.1 dB。这项研究对海洋装备领域抑制空化、降低流致噪声和改善水动力性能具有一定的参考意义。 | 李智健 王巍 唐滔 安昭阳 纪祥 刘明雨 | 2022 | 中国造船2022，63，4： | 0 |
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