高温高压下1,3-丁二烯层流燃烧特性研究

高速纹影系统结合定容燃烧弹和定压燃烧弹测量了高温(298～398 K)高压(0.1～1 MPa)下,当量比为0.7～1.6的1,3-丁二烯/空气和1,3-丁二烯/氧气/氦气混合气的层流燃烧速度,并分析了温度和压力对层流燃烧速度的影响。利用实验数据对现有1,3-丁二烯的化学反应动力学模型计算值进行了验证,并通过敏感性分析了基元反应对于层流燃烧速度的敏感性。     

流体黏度的实验研究

基于落球法和毛细管法测定黏度的原理,利用泊肃叶公式,制作了测量流体黏度的装置.更换不同规格的圆管,黏度的测量范围为10-3~100Pa·s.水和羧甲基纤维素钠溶液黏度的测量值与参考文献报道结果一致.     

Experimental Study on Physical Mechanism of Drag Reduction of Hydrophobic Materials in Laminar Flow

We experimentally study the physical mechanism of the drag reduction of hydrophobic materials in the macroscopic scale. The experiment includes the drag and velocity measurements of laminar boundary layer flow over flat plates, and the observation of air bubbles on the surfaces. The plate surfaces have different wetting and roughness properties. In the drag measurements, the plates with bubbles on the surfaces lead to drag reduction, but not for those without bubbles. Velocity measurement confirms that the flow is laminar and gives apparent fluid slip on the plate wall with bubbles. In observation, air bubbles in macroscopic size emerge and enlarge on hydrophobic surfaces but not on hydrophilic surfaces. Therefore, the drag reduction of hydrophobic materials is explained by the generation of air bubbles of macroscopic size that cause the apparent velocity slip.     

微流控层流技术的研究

基于微型通道自身的层流特点而发展起来的多相层流技术, 从最初的液-液微萃取开始,由于其结构加工简单、操作方便和分析功能强大,已逐渐发展成为一种加工分析方法,为微流控分析的研究应用打开了一个崭新的局面.本文概述了层流的基本原理,总结了近10年来在这方面的研究,包括层流界面间的分子扩散、转移现象和化学反应,以及层流刻蚀加工技术及其在制备纳米材料和在生命医学方面的应用.具体介绍了应用层流技术进行微芯片的加工制作,微型反应器的制备,离子、分子的分离分析,聚合物薄膜的形成和应用,微通道内有机合成反应的控制,溶液的浓度梯度控制以及在免疫检测中的应用,对细胞、生物大分子的操作控制,以及对生物试剂的预处理分析等.     

Direct Numerical Simulation of Supersonic Turbulent Boundary Layer Flow

Direct numerical simulations of a spatially evolving supersonic flat-plate turbulent boundary layer flow with free Mach number M∞ = 2.25 and Reynolds number Re = 365000/in are performed. The transition process from laminar to turbulent flow is obtained by solving the three-dimensional compressible Navier-Stokes equations, using high-order accurate difference schemes. The obtained statistical results agree well with the experimental and theoretical data. From the numerical results it can be seen that the transition process under the considered conditions is the process which skips the Tollmien-Schlichting instability and the second instability through the instability of high gradient shear layer and becomes of laminar flow breakdown. This means that the transition process is a bypass-type transition process. The spanwise asymmetry of the disturbance locally upstream imposed is important to induce the bypass-type transition. Furthermore, with increasing the time disturbance frequency the transition will delay. When the time disturbance frequency is large enough, the transition will disappear.     

Self—Organized Criticality Processes in HL—1M Tokamak Plasma

We study the dynamics of laminar time between successive bursts in anomalous particle flux measured at the HL-1M tokamak plasma edge.The results reveal that the flux fluctuations are self-similar in a narrow range of time scales and that their probability distribution function is not Gaussian.These properties are not consistent with those predicted by self-organized criticality(SOC)models as well as the running sand-pile SOC model developed by Hwa and Kardar.     

Acoustic Calculation for Supersonic Turbulent Boundary Layer Flow

An approach which combines direct numerical simulation （DNS） with the Lighthill acoustic analogy theory is used to study the potential noise sources during the transition process of a Mach 2.25 flat plate boundary layer. The quadrupole sound sources due to the flow fluctuations and the dipole sound sources due to the fluctuating surface stress are obtained. Numerical results suggest that formation of the high shear layers leads to a dramatic amplification of amplitude of the fluctuating quadrupole sound sources. Compared with the quadrupole sound source, the energy of dipole sound source is concentrated in the relatively low frequency range.     

非共沸混合工质水平管内凝结换热折算因子的实验关联

1前言前文山提出了计算环状流和波状分层流型下非共沸混合工质在水平管内凝结的换热系数的折算方法。租界面温度Ti的取值对计算结果影响很大。现在常用的方法是根据液膜和气相区传热传质的经验公式确定问，不仅计算工作量大，且无公认的计算方式。这给工程计算带来许多不便。本文取Ti二（Tv十几w，即气相温度Tv和壁面温度见的算术平均值，以计算相界面上的平衡参数，并将前文中的折算因子计算式改为如下形式：对环状流将由于相界面温度的取法所引起的误差归于用实验数据确定的经验系数A、B与经验指数p、q。式中Ja为雅各布数，无量纲温度0…