亭子口水电站跌坎消力池减压模型试验研究

采用1:40减压模型,通过测试流态、水下噪声和脉动压力等水力参数,对亭子口水电站闸墩尾部跌坎式底流消力池的空化空蚀特性进行了研究。成果表明：闸墩尾部区域存在强度为发展阶段的剪切流空化,采用8.00 m高度的跌坎消力池后,消力池底板空蚀破坏的可能性较小;但消力池边墙与闸墩内壁侧扩距离较小时,边墙空蚀破坏的可能性较大;消力池边墙与闸墩内壁侧扩距离增至4.20 m时,边墙空蚀破坏的可能性显著降低。     

Utilizing Iron's Attractive Chemical and Magnetic Properties in Microrocket Design,Extended Motion,and Unique Performance

All‐in‐one material for microrocket propulsion featuring acid‐based bubble generation and magnetic guidance is presented. Electrochemically deposited iron serves as both a propellant, toward highly efficient self‐propulsion in acidic environments, and as a magnetic component enabling complete motion control. The new microrockets display longer lifetime and higher propulsion efficiency compared to previously reported active metal zinc‐based microrockets due to the chemical properties of iron and the unique structure of the microrockets. These iron‐based microrockets also demonstrate unique and attractive cargo towing and autonomous release capabilities. The latter is realized upon loss of the magnetic properties due to acid‐driven iron dissolution. More interestingly, these bubble‐propelled microrockets assemble via magnetic interactions into a variety of complex configurations and train structures, which enrich the behavior of micromachines. Modeling of the magnetic forces during the microrocket assembly and cargo capture confirms these unique experimentally observed assembly and cargo‐towing behaviors. These findings provide a new concept of blending propellant and magnetic components into one, toward simplifying the design and fabrication of artificial micro/nanomachines, realizing new functions and capabilities for a variety of future applications.     

三相反应器的气含率与液速分布和数值模拟

研究了一定操作条件下的气液固三相鼓泡床反应器的气含率和液体轴向速度分布,讨论了气、液表观速度对气含率和液体轴向速度分布的影响,比较了三相与两相鼓泡床中气含率和液体轴向速度分布,用拟两相的双流体模型计算了三相鼓泡床中的气含率和液体轴向速度．结果表明,模拟结果与实验结果一致．     

基于Snake模型的铁路铸件气孔检测

研究Snake模型在铁路铸件数字化辐射成像(DR)图像气孔缺陷自动检测中的应用,改进初始轮廓点的获取方法。综合运用阈值分割和区域生长方法得到各气孔的重心,依次对其采用一种射线法得到初始控制点,对初始控制点进行收敛和拟合。对仿真图像的实验结果表明,最小检测尺寸为3×3,能较好地收敛到目标的凹陷区域;对实际铁路铸件DR图像检测的实验结果表明,该方法能准确得到检测区域内多个气孔缺陷的轮廓,不会检测出伪缺陷,具有较高的自动化程度。     

水下气泡幕激光后向散射功率衰减特性实验研究

针对水下气泡幕的激光后向散射功率衰减特性,设计了实验系统,采用不同波长、不同发射功率的激光对不同密度、不同厚度、不同距离的气泡幕进行照射,采用激光功率计对后向散射光功率进行测量,并对数据进行了分析。结果表明：蓝绿光的后向散射特性较好;后向散射光功率与发射光功率及气泡幕厚度呈正比;水下气泡幕的激光后向散射特性与气泡密度、气泡幕距离关系密切。     

楔形流道内单气泡动力学行为特性研究

楔形流道是一个具有复杂物理边界的流场,对其内部气液两相流动特性的研究具有现实意义.该文首先对孔板流量计内掺混气泡的两相流体建立了数学模型,采用贴体坐标系同位网格下的SIMPLE算法解决了速度与压力的耦合问题,改进了贴体坐标下Level Set方法,并利用其对楔形孔板流量计内单气泡两相流场进行了模拟.针对不同Re数和不同We数时其内部流场的模拟结果进行了分析,得出流场内气泡形态及其流动特性的变化规律.     

深浅水变换带地震资料子波处理技术应用研究

在海上地震勘探中,气枪激发时所产生的气泡震荡影响了地震资料的信噪比和分辨率。目前使用较为广泛的方法是应用远场子波预测反褶积来压制震源气泡的影响。在浅水中压制由于空气枪产生的气泡振荡的低频起到了一定作用,可也压制了小部分的有效频率,这对精细勘探来讲是不足的。为满足精细勘探需要,本文通过深水可完整记录直达波的特点,在测线的近道上应用直达波和海底反射波的组合得到统计子波的方法来压制气泡。结果表明气泡得到了很好的压制,并且较好地保护了有效频率。     

基于CLSVOF方法的三维单个上升气泡运动的数值模拟

运用CLSVOF方法数值模拟了三维单气泡在液体中的上升和变形过程,分别考察了液体的表面张力和浮力对上升气泡变形的影响。计算结果表明:CLSVOF方法能比较精确地跟踪三维单气泡在液体中的上升过程;在相同密度比和粘度比情况下,随着液体表面张力的减小和液体浮力的增大,气泡底部形成的射流使得气泡下缘凹陷变得明显,变形幅度加大,射流穿透气泡的时间提前。     

EFFECT OF A PROPELLER AND GAS DIFFUSION ON BUBBLE NUCLEI DISTRIBUTION IN A LIQUID

A multi-bubble dynamics code accounting for gas diffusion in the liquid and through the bubble wall was developed and used to study the modification of a bubble nuclei population dynamics by a propeller.The propeller flow field was obtained using a Reynolds-Averaged Navier-Stokes(RANS) solver and bubble nuclei populations were propagated in this field.The numerical pro-cedure enabled establishment of the possibility of production behind the propeller of relatively large visible bubbles starting from typical ocean nuclei size distributions.The resulting larger bubbles are seen to cluster in the blade wakes and tip vortices.Parametric investigations of the initial nuclei size distribution,the dissolved gas concentration,and the cavitation number were conducted to ide-ntify their effects on bubble entrainment and the resultant void fractions and bubble distribution modifications downstream from the propeller.Imposed synthetic turbulence-like fluctuations unto the average RANS flow field were also used to study the effect avera-ging in the RANS procedure has on the results.     

基于废弃物利用的自保温墙体配套砂浆制备及性能研究

采用淤泥陶砂、废弃加气混凝土结合传热系数小的玻化微珠为砂浆骨料,基于"复合化"思想,制备自保温墙体配套砂浆。采用正交实验探讨混掺砂浆的合理配比,控制4项参数:胶凝材料用量、陶砂(或废料)与玻化微珠体积比、硅灰取代量和胶粉掺量,以干容重、抗压强度、导热系数为考核指标,制备综合利废效果最佳的新型混掺复合保温砂浆。结果表明,陶砂玻化微珠复合砂浆导热系数0.16～0.29W/(m.K),随着陶玻比增大而增大,因此陶砂体积含量增加有利于提高保温性能,加气废料玻化微珠复合砂浆的导热系数0.10～1.14W/(m.K),与陶砂复合保温砂浆相比,有较大的降低。