射流式氧发生器的三维模拟研究

实现了对射流式氧发生器的三维仿真模拟,给出了氧发生器内部流场结构、各组分的分布状态等信息。研究了射流孔结构对氧发生器性能的影响。指出即便是具有相同比表面积的不同射流孔排布方式,也会对发生器性能产生影响。此外,逆向射流式氧发生器反应器中气体从双侧进入对于减小发生器对气体的阻力具有重要作用。     

Hydrodynamics of natural oscillations of neutrally buoyant bodies in a layer of continuously stratified fluid

The flow patterns induced by floats of different shapes (sphere, short and long cylinders) freely sinking to the neutral-buoyancy horizon in a continuously stratified fluid are investigated using optical methods. General flow elements, both large-scale (waves, vortices, hydrodynamic wake) and fine-scale (boundary layers, extended autocumulative jets), are distinguished. For large times, the float oscillation frequencies are of the order of or greater than the buoyancy frequency of the medium. This indicates the significant effect of the induced flows on the motion of the float.     

溶液中金属元素的激光诱导击穿光谱

利用激光击穿光谱的方法对水溶液样品中的金属元素进行定性和定量分析。分别采用竖直喷流（口径0.5 mm）和静止液面两种样品采样模式,针对不同质量浓度的Cd,Fe,Al和Pb元素进行了检测分析并得到了其定标曲线(线性拟合相关度基本在0.99以上),初步确定了４种元素在喷流模式下的检测限为0.206 5(Cd),0.147 6(Fe),0.061 9(Al)和0.200 9(Pb) g/L;静止液面模式下的检测限为0.050 1(Cd),0.023 9(Fe),0.014 8(Al)和0.006 9(Pb) g/L。实验所得的结果为检测工业废水中金属元素的含量提供了依据。     

AUTOMORPHISMS OF CURVES

The article deals with local symmetries of the infinite-order jet space of C^∞-smooth curves in ?^m+1 (m ≥ 1). Transformations under consideration are the most general possible: they need not preserve the distinction between dependent and independent variables and the order of derivatives may be arbitrarily changed. Unlike the common prolonged point and Lie's contact transformations, they destroy the finite-order jet spaces.     

Mitigated membrane fouling in a vertical submerged membrane bioreactor (VSMBR)

In a laboratory-scale study, characteristics of membrane fouling in an A/O (anoxic/oxic) series membrane bioreactor (MBR) and in a vertical submerged membrane bioreactor (VSMBR) treating synthetic wastewater were compared under the same operating conditions. Accordingly, fouling characteristics of a pilot-scale VSMBR treating municipal wastewater were studied under various operating conditions. Various physical, chemical, and biological factors were used to describe membrane resistances. As a result, it was concluded that high concentrations of extracellular polymeric substances (EPS), high viscosity and a high sludge volume index (SVI) corresponded to high membrane resistance indicating severe membrane fouling in both the laboratory-scale MBRs and the pilot-scale VSMBR. In addition, high fouling potential was observed in the pilot-scale VSMBR at 60-day sludge retention time (SRT). In this case, as hydraulic retention time (HRT) decreased from 10 to 4 h, EPS concentrations increased and the average particle size increased, leading to reduced settling of the sludge and increased membrane fouling. To mitigate fouling, two different methods using air bubble jets were adopted in the pilot-scale VSMBR. As a result, it was found that air backwashing was more efficient for fouling mitigation than was air scouring.     

Exact Helically Symmetric Plasma Equilibria

The global helically symmetric plasma equilibria are derived as exact solutions to the JFKO equation. The obtained plasma equilibria model astrophysical jets and provide a helically symmetric counterexample to the well-known Parker theorem.     

矩形喷嘴平行射流组流体动力学特性

依据动量和质量守恒原理,建立了这平行射流组流动行为的数学模型,并获得了模型的解析解研究了矩形喷嘴平行射流组的流动行为特性。最后,计算结果与实验结果进行了比较。     

Theoretical summary of Hard Probes 2010

I provide a theoretical summary of some of the results from Hard Probes 2010.     

Born-Oppenheimer breakdown effects and hyperfine structure in the rotational spectra of SbF and SbCl

Pure rotational spectra have been measured for the ground electronic states of SbF and SbCl. The molecules were prepared by laser ablation of Sb metal in the presence of SF₆ or Cl₂, respectively. Their spectra were measured with a cavity pulsed jet Fourier transform microwave spectrometer. Although both molecules have two unpaired electrons, they are subject to Hund’s coupling case (c), and have X₁0⁺ ground states. The spectra have been interpreted with the formalism of ¹Σ⁺ molecules. For both molecules spectra of several isotopomers have been measured in the ground and first excited vibrational states. Large hyperfine splittings attributable to both nuclear quadrupole coupling and nuclear spin-rotation coupling have been observed. A Dunham-type analysis has produced unusually large Born-Oppenheimer breakdown parameters, which are interpreted in terms of the electronic structures of the molecules.     

水下超声速气体射流气液两相复杂流动研究

本文实验研究了水下超声速气体射流气液两相复杂流动。利用高速摄影仪和电子相机分别实时记录了过膨胀超声速工况水下气体射流的喷射状态和整体形貌,显示了不同工况水下高速气体垂直射流的演化过程和动态不稳定性形貌。研究结果表明:在射流的初始段存在与射流内部复杂波系相关的激波反馈特性,激波反馈特性发生之前存在能量积聚的高频低幅的胀鼓过程,二者均随机发生;在射流的主体段,在气水掺混和卷吸大规模能量交换作用下,射流呈现随机的偏摆效应,并且偏摆受环境流场影响明显。