基于MATLAB的二元线性回归在小孔流速实验中的应用

利用MATLAB软件对相关物理量进行二元线性回归拟合,求出了拟合曲线的待定参数和置信区间,拟合曲线与实验测试数据点符合较好。总结出小孔流速的经验公式,并对减少实验误差的途径进行了讨论。     

高坝挑流冲刷坑中掺气水流的流速量测及其特性分析

本文研究了利用热膜技术量测掺气水流的时均流速和紊动结构有关的技术问题，首次成功地量测了三峡溢流坝模型冲坑中掺气水流的时均流速与脉动流速，并对脉动流速和脉动压强的相关关系作了分析研究，把目前冲坑水流特性的研究推进了一步，对研究冲刷过程和探讨消能机理有重要的理论价值与实际意义     

基于室温液态金属热虹吸效应的自驱动热量传递方法的数值模拟

利用芯片热量驱动的液态金属散热技术是一种高效灵巧的热管理方法,在许多应用场合具有独特价值.本文采用数值手段对基于室温液态金属热虹吸效应的自驱动热量传递方法进行了研究,探明了冷端的壁温、环路方向、环路管径的大小对此种方法流动、传热性能的影响,为该技术的实际应用提供了数据支持。     

Large eddy simulations of a circular orifice jet with and without a cross-sectional exit plate

The effect of a cross-sectional exit plane on the downstream mixing characteristics of a circular turbulent jet is in- vestigated using large eddy simulation （LES）. The turbulent jet is issued from an orifice-type nozzle at an exit Reynolds number of 5 ×104. Both instantaneous and statistical velocity fields of the jet are provided. Results show that the rates of the mean velocity decay and jet spread are both higher in the case with the exit plate than without it. The existence of the plate is found to increase the downstream entrainment rate by about 10% on average over the axial range of 8-30de （exit diameter）. Also, the presence of the plate enables the formation of vortex rings to occur further downstream by 0.5-1 .Ode. A physical insight into the near-field jet is provided to explain the importance of the boundary conditions in the evolution of a turbulent jet. In addition, a method of using the decay of the centreline velocity and the half-width of the jet to calculate the entrainment rate is proposed.     

Analytical investigation velocity fields on mean and turbulent of a plane jet

This paper analyses the downstream developments of the mean and the turbulent velocity fields of a plane jet. Based on the conservation of mass and the conservation of momentum, the mean-velocity half width （reflecting the jet spread rate） and the relative mass flow rate （jet entrainment） are related to the decay rate of the centreline mean velocity. These relations are not subject to self-preservation. Both analytical and experimental results suggest that the jet spread rate （K1） and the entrainment rate （K3） （and thus the decay rate K2） can be well estimated from the centreline velocity, i.e., K1 ≈ 0.6K2 and K3 ∝K2. The effect of initial mean velocity and RMS velocity profiles on the downstream mean velocity field appears to be embodied in the constants K1 K2 and K3. The analytical relationship for the self-preserving Reynolds shear stress, obtained for the first time, works well.     

圆直管内层流振荡流的摩擦特性

研究了在谐波压力梯度作用下圆管内层流振荡流的流速分布形态、断面平均流速、驱动功率损耗及摩擦特性，并对管内单方向定常流的范宁摩擦系数公式进行扩展，建立了用于管内振荡流的摩擦系数计算式。摩擦系数理论计算结果与实验显示了较好的一致性。     

气体超声波流量计

本文叙述的气体超声波流量计,采用了声阻抗匹配的超声波换能器,用微型计算机进行测量及数据处理,克服了时差法的温度效应问题,使仪器有更大的灵活性和可靠性.本文给出了实验室和天然气管线现场的试验结果;超声波流量计与孔板流量计测量对比,其误差在0.6％以内.此外,文章还对设计方法和影响测量精度等某些因素作了讨论.     

EXISTENCE AND UNIQUENESS OF WEAK SOLUTIONS FOR TWO-DIMENSIONAL MODIFIED NAVIER-STOKES EQUATIONS

This paper studies a two-dimensional modified Navier-stokes equations. The author shows the existence and uniqueness of weak solutions for this equation by Galerkin method in bounded domains. The result is further extended to the case of unbounded channel-like domains.     

氢化物原子荧光光谱法工作条件的选择

本文对氢化物原子荧光法测定化探、环保、生物及冶金试样中砷、锑、铋，硒，碲及汞时仪器工作条件的选择作了讨论。原子荧光的激发辐射源无极放电灯在谐振腔内与微波的有效耦合和微波功率的大小对分析质量影响最大；原子化炉温度和形状决定原子化效率和工作曲线的效率；载气流速、KBH4浓度和用量选择不当，则会导致信噪比、原子荧光量子效率降低和光谱散射干扰等。因而提高分析质量的关键在于仪器工作条件的最优化。     

氢气燃烧火焰颜色影响因素的研究及演示方案再设计

基于对氢气燃烧火焰颜色的不同解释,从焰色反应、火焰温度、气体流速等3方面影响因素设计方案进行实验研究,得出影响氢气火焰颜色的主要因素是气流速度、火焰温度及药品的焰色反应。巧用球形干燥管既控制气流速度、又控制火焰温度的特点,设计出可以观察到氢气燃烧火焰呈明显蓝色的演示装置。用可现取的仪器药品、可执行的实验方案、可重现的实验现象、可检验的实验结果,验证了教材中关于氢气燃烧火焰颜色的论述,突破了实际操作中氢气燃烧颜色不易观察的局限。