Ar(^(3)P_(0 ,2) )与H_(2)O传能反应生成OH自由基的机理和初生态转动分布

利用流动余辉技术研究了亚稳态Ar(3P0 ,2 )与H2 O碰撞传能反应生成OH自由基的动力学过程 ,测定了产物的转动态分布 ,并讨论了OH自由基在实验条件下的转动驰豫情况。

He(2~3S)与含氢卤代甲烷传能反应中产生的CH(A^2Δ,ν′=0)的新生态转动分布

流动余辉技术在基元反应动力学研究中已得到了广泛应用。当亚稳态稀有气体原子与某些分子发生传能反应时,母体分子解离产生一些较小的激发态碎片。通过测量碎片的发射光谱可以获得产物内能分布以及解离过程的动力学信息。使用该技术,Someda和Roychowdhury分别研究了He(2~3S)与NH_3和PF_3的反应,获得了NH(A,C)和PF(A)的内能分布规律,并讨论了解离反应的机理。

与HBr（Χ1Σ+v″=1,J″=12）碰撞的CO2（0000）转动态分布

利用受激拉曼泵浦激发HBr分子至Χ1Σ+(1,12)激发态,由相干反斯托克斯-拉曼散射(CARS)光谱确定分子的激发.通过测量CARS谱相对强度,得到了HBr分子Χ1Σ+态(1,12)能级的布居数密度为n1=0.54×10^13 cm^-3.在一次碰撞条件下,测量碰撞前后CO2(0000,J)态的激光感应荧光强度比,得到CO2转动态的双指数分布.由二分量指数拟合得到Ta=261 K的低能分布和Tb=978 K的高能分布.结果表明,碰撞后约有65%的分子处于低J态,属于弹性或近弹性的弱碰撞;约有35%的分子处于高J态,属于非弹性的强碰撞.在振动-转动平动(V-RT)能量转移过程中,CO2(0000,J)态的总出现速率系数为(1.3±0.3)×10^-10 cm^3 molecule^-1s^-1;低转动态的平均倒空速率系数为(2.9±0.8)×10^-10 cm^3 molecule-1s-1.总的出现速率系数比平均倒空速率系数小,但在量级上保持一致.对CO2 J=60-74高转动态,随着J值的增加,质心平移温度和质心平移能的平均改变增加.对低转动态,在碰撞过程中,J态既可能出现也可能被倒空,平移能的改变不易确定.

刚性挡土墙绕墙顶转动情况下被动土压力的分布

根据土体微分单元体的静力平衡条件,建立了挡土墙绕墙顶转动情况下被动土压力分布的计算表达式,同时进行了被动土压力分布、合力及作用点与库仑土压力、实测结果的分析比较。结果表明:该公式很好地反映了实测曲线的非线性分布,同时被动土压力合力与库仑被动土压力基本相同,合力作用点接近于0.27倍墙高处。

Lead anthropogenic transfer and transformation in China

Information on lead redistribution and speciation changes in anthrosphere can help to analyze the whole lead cycle on the earth. Lead life cycle was traced based on the concepts of anthropogenic transfer and transformation. Lead transfer and the distribution of chemical species throughout the anthropogenic flow were identified in 2010 in China. The results show that 1.85 Mt lead ore was consumed(besides 1.287 Mt imported concentrated ore and 1.39 Mt lead scraps. After undergoing transformations, 3.53 Mt lead entered end services in chemical species of Pb, Pb O2 and PbSO4, altogether accounting for over 80% of the total lead products. Finally, 2.10 Mt ore was emitted into the environment in such species as PbSO4(26%), PbO(19%) and Pb(15%). Lead transfer begins in primary raw material sectors, and then transfers to manufacturing sectors. Lead provides services mainly in such industrial sectors as transportation, electrical power and buildings or construction.

Simulation of Solid Suspension in a Stirred Tank Using CFD-DEM Coupled Approach＊

Computational fluid dynamics-discrete element method(CFD-DEM) coupled approach was employed to simulate the solid suspension behavior in a Rushton stirred tank with consideration of transitional and rotational motions of millions of particles with complex interactions with liquid and the rotating impeller. The simulations were satisfactorily validated with experimental data in literature in terms of measured particle velocities in the tank.Influences of operating conditions and physical properties of particles(i.e., particle diameter and density) on the two-phase flow field in the stirred tank involving particle distribution, particle velocity and vortex were studied.The wide distribution of particle angular velocity ranging from 0 to 105r·min 1is revealed. The Magnus force is comparable to the drag force during the particle movement in the tank. The strong particle rotation will generate extra shear force on the particles so that the particle morphology may be affected, especially in the bio-/polymer-product related processes. It can be concluded that the CFD-DEM coupled approach provides a theoretical way to understand the physics of particle movement in micro- to macro-scales in the solid suspension of a stirred tank.

UV Photolysis of N2O Isotopomers： Isotopic Fractionations and Product Rotational Quantum State Distributions

The time-dependent quantum wave packet method is used to study the dynamics of the pho- todissociation processes for the isotopomers 14N14N16O, 14N15N16O, 15N14N16O, 15N15N16O, 14N14N17O, and 14N14N18O. In general, the computed isotopic fractionation factors derived from the absorption cross sections of five heavy isotopomers are in good agreement with the experimental results. Relative to the 14NI4N16O isotopomer, the N2 rotational state distributions for the isotopically nitrogen substituted N2O are found to be entirely shifted to higher rotational states. Similar to its isotopic fractionation factors, the N2 rotational state distributions for the asymmetric isotopomers 14N15N16O and 15N14N16O are found to be observably different.

Drag Torque Prediction Model for the Wet Clutches

Reduction of drag torque in disengaged wet clutch is one of important potentials for vehicle transmission improvement. The flow of the oil film in clutch clearance is investigated. A three-dimension Navier-Stokes(N-S) equation based on laminar flow is presented to model the drag torque. Pressure and speed distribution in radial and circumferential directions are deduced. The theoretical analysis reveals that oil flow acceleration in radial direction caused by centrifugal force is the key reason for the shrinking of oil film as constant feeding flow rate. The peak drag torque occurs at the beginning of oil film shrinking. A variable is introduced to describe effective oil film area and drag torque after oil film shrinking is well evaluated with the variable. Under the working condition, tests were made to obtain drag torque curves at different clutch speed and oil viscosity. The tests confirm that simulation results agree with test data. The model performs well in the prediction of drag torque and lays a theoretical foundation to reduce it.

准经典轨线法研究交换反应H(D)+SH/SD的动力学性质

硫在氢气中的燃烧反应在气象化学、燃烧反应和大气污染中都扮演着重要的角色,近年来一直受到广泛关注,其逆反应也渐渐成为人们的研究对象.以Lu¨等得到的精确势能面(Lu¨S J,Zhang P Y,Han K L,He G Z 2012 J.Chem.Phys.136 94308)为基础,用准经典轨线法对交换反应H(D)+SH/SD的动力学性质进行了研究.计算了包括反应截面、速率常数、不透明函数、产物振动和转动分布等在内的标量性质和包括产物散射方向、转动角动量定向和取向性质在内的矢量性质.详细分析了碰撞能量和同位素效应对反应H(D)+SH/SD的动力学性质的影响.结果表明,随着碰撞能量的增加,反应截面逐渐增大,产物的后向散射逐渐减弱,产物转动角动量的取向和定向性质逐渐增强;另外,同位素效应对反应的动力学性质也有明显的影响.以反应动力学性质和势能面为基础,详细讨论了反应H(D)+SH/SD的反应机制.

Effects of blade rotation angle deviations on mixed-flow pump hydraulic performance

By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades had rotation angle deviations, the hydraulic performance curves of the mixed-flow pump would move. With a positive deviation, the curves moved towards the large flow rate; with a negative deviation, the curves moved towards the small flow rate. When some blades had rotation angle deviations, the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased; the larger the deviation, the greater the decrease. When a single blade had a large rotation angle deviation, a rather clear low pressure area was formed, lowering the cavitation performance. When two adjacent blades changed simultaneously, under the small flow rate condition, adverse pressure gradient and flow separation occurred in the flow field, and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly. Near the best efficiency point（BEP）, the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage, with an even larger area. Compared to the effect of two adjacent blades, two alternate blades, when changed simultaneously, made the mixed-flow pump slightly less efficient, but with a flatter efficiency curve and relatively wider high efficiency area. By fitting the test results, a functional relation among the BEP of the mixed-flow pump QBEP, the number of deviated blades N, and blade rotation angle deviation α was established, thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.

Experimental Investigation of Effects of Distributed Riblets on Aerodynamic Performance of a Low-speed Compressor

It is well known that riblet applied on compressor blades is a promising flow control technique. However, detailed investigation of its effects on the flow field of turbomachinery is rare in existing literatures. This paper presents a detailed experimental investigation of effects of distributed riblet on the flow field of an axial compressor iso- lated-rotor stage. The research was performed in a large-scale facility respectively with two configurations, in- eluding grooved hub, and grooved surface on both hub and partial suction surface. The riblet film is rectangle grooved type with a height of 0.1 ram. The flow field at 10% chord downstream from the cascade trailing edge was measured using a mini five-hole pressure probe and a total pressure probe. The testing was conducted at sev- eral operational points under two reduced rotational speeds. Stagnation pressure loss in rotational frame was cal- culated and compared with the control test in which a smooth film was applied to the corresponding position. Results show that with the grooved hub configuration at the design operation point of the lower rotational speed, the riblet film provides an obvious improvement of a 48% reduction of total pressure loss in rotational frame. Also, a distinct weaken hub comer vortex was identified. In the meantime, there exists a deviation of flow angle about 5 degrees at 20%-80% span which previously was not considered to be the affected region.

Numerical simulation of gurney flaps lift-enhancement on a low reynolds number airfoil

Two-dimensional steady Reynolds-averaged Navier-Stokes （RANS） equations with transition shear stress transport （SST） model were solved to investigate the effects of Gumey flaps on the aerodynamic performance of a low Reynolds number airfoil. This airfoil was designed for flight vehicles operating at 20 km altitude with freestream velocity of 25 rn/s. The chord length （C） of this airfoil is 5 m and the corresponding Reynolds number is 7.76× 10^5. Gurney flaps with the heights ranging from 0.25%C to 3%C were investigated. It has been shown that Gurney flaps can enhance not only the prestall lift but also lift-to-drag ratio in a certain range of angles of attack. Specially, at cruise angle of attack （3°）, Gurney flap with the height of 0.5%C can increase lift-to-drag ratio and lift coefficient by 1.6% and 12.8%, respectively. Furthermore, the mechanisms of Gumey flaps to improve the aerodynamic performance were illustrated by analyzing the surface pressure distribution, streamlines and trailing-edge flow structure for this low Reynolds number airfoil. Specially, distinguished from some other numerical researches, the flow details such as the laminar separation bubble and transition phenomena for low Reynolds number airfoil with Gumey flaps were investigated and it was found that Gurney flaps can delay the transition onset position at small angles of attack （≤2°）. However, with the increase of angles of attack, Gurney flaps will promote the boundary layer transition.

A New Technique:Research and industrial application of a novel compound permanent magnet synchronous machine

We propose a novel kind of compound permanent magnet synchronous machine (CPMSM), which is applicable in low-speed and high-torque situations. We first explain the structure of the CPMSM. Based on theoretically deducing the calculation formulae of the CPMSM electromagnetic parameters, we analyze the operating characteristics of the CPMSM, and obtain the power-angle curves and working curves. The no-load magnetic field distribution and the cogging torque are analyzed by applying the finite element method of three-dimensional (3D) magnetic fields, to determine the no-load leakage coefficient and the waveform of the cogging torque. Furthermore, the optimal parameters of the permanent magnet for reducing the cogging torque are determined. An important application target of the CPMSM is in directdrive pumping units. We have installed and tested a direct- drive pumping unit in an existing oil well. Test results show that the power consumption of the direct-drive pumping unit driven by CPMSM is 61.1% of that of the beam-pumping unit, and that the floor space and weight are only 50% of those of a beam-pumping unit. The noise output does not exceed 58 dB in a range of 1 m around the machine when the machine is 1.5 m from the ground.