Turbulent diffusion of passive impurity in gas suspension at large reynolds numbers

Experimental results on the turbulent diffusion of passive impurity in a gas-suspension flow in a vertical cylindrical channel are outlined. On the basis of introducing simple approximations of spectral functions of the velocity pulsations, the influence of the discrete phase on the turbulent diffusion coefficient is estimated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 59, No. 4, pp. 631–634, October, 1990.     

Turbulent diffusion of heat in dilute disperse flows

On the basis of inserting random terms in the heat-transfer equations in a gas suspension, the influence of particles on turbulent heat diffusion and the behavior of spectral functions of turbulent temperature fluctuations are investigated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 5, pp. 746–752, May, 1988.     

Coherent diffusion of isotopic impurities in solid helium

A theory of coherent diffusion (impuriton propagation) of dilute isotopic impurities in solid He is described. An expression for the mean square distance R ² (t) traveled by the impurity is derived. For short times pure band propagation occurs and so R ² (t) grows as t ². For times longer than a characteristic impurity-phonon scattering time this time dependence becomes linear, and a diffusion constant can be defined. This characteristic scattering time is estimated to be ~7 × 10^–5 T ^–9 sec (T in K) for a ³He impurity in ⁴He at V _m = 21 cm³/mole. The corresponding diffusion constant is consistent with that measured in the NMR experiment of Allen and Richards if the ³He-⁴He tunneling frequency J ₃₄ is taken as 7 × 10⁵ sec^–1.     

The problem of turbulent diffusion in active impurities

We examine the problem of turbulent diffusion in dynamically active gases in an air stream. We found the relationship between the diffusion factor and the Richardson number, as well as the relationship between the gas concentration of the gas-release wall from the decisive parameters, A method is presented for the numerical solution of the resulting system of relationships for the diffusion of an active gas, and the results of the calculation are also presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 16, No. 1, pp. 59–66, January, 1969.     

Diffusion and mixing of passive impurities in a linear velocity field

It is shown that the mixing process is described by a Lagrangian Green's function. The latter is obtained at both the dynamical and the statistical levels, which permits application of the results to turbulent media.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 6, pp. 924–931, December, 1982.     

Turbulent diffusion of inertial particles in the field of mass forces

Based on Corrsin's hypothesis of independent averaging of the liquid particle trajectories and of the Euler correlations of velocity fluctuations we have analyzed the turbulent dissipation of an inertial particle impurity with regard to the averaged sliding of discrete and continuous phases.G. M. Krzhizhanovskii Power Institute, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 64, No. 2, pp 141–149, February, 1993.     

Turbulent mass transfer and diffusion in polymer solutions reducing friction drag

A comparison is presented between the computed and experimental data on turbulent mass transfer and diffusion in the near-wall domain of a channel and plate.Translated from Inzhernerno-Fizicheskii Zhurnal, Vol. 54, No. 6, pp. 963–970, June, 1988.     

Boundary effect on the mixing and transport of passive impurities in a nonstationary flow

The simplest model of a point topographic vortex situated near a linear boundary in a nonstationary incident flow is considered. The results of numerical experiments reveal a new feature in the behavior of trajectories that is not observed in absence of the boundary. A criterion for distinguishing such trajectories is proposed.     

扩散层PTFE载量对被动式直接甲醇燃料电池性能的影响

在被动式直接甲醇燃料电池(DMFC)的扩散层中,处理好水、气、电子的通道对电池性能有着十分重要的作用.本研究分别用质量百分比浓度为10%、20%、30%、40%的PTFE乳液进行疏水处理的碳布组装成被动式DMFC以及测试系统.通过稳态电流-电压极化曲线法和交流阻抗法,研究了扩散层中的不同PTFE载量对被动式DMFC电化学性能的影响.研究结果表明,电池开路电压随着阳极扩散层中PTFE载量的增加而上升,电池内阻也随着扩散层中PTFE载量的增加而增加.在阳极,电池性能随着扩散层中PTFE载量的增加而下降,在阴极,用10%PTFE乳液处理的碳布对被动式DMFC性能表现最好.     

Increased homogenous clusters in superconducting paths with diffusion of optimum Ni impurities into Bi-2223 crystal

This study deals with variations of electrical and superconducting features of Bi-2223 superconducting materials exposed to Ni impurity diffusion at different annealing temperatures (650 °C?≤?T?≤?850 °C) by temperature-dependent resistivity measurements. It is found that the characteristic properties improve with annealing temperature up to 700 °C as a result of enhancement in the truly-metallic characteristics, interaction quality, formation of Cooper-pairs and overlapping of Cu-3d and O-2p wave functions. Similarly, the optimum annealing temperature of 700 °C diminishes the omnipresent flaws and structural defects. Additionally, we design a strong theory (Percolation) to discuss the role of nickel impurities on fundamental aspects of material science and physical quantities as regards stabilization of superconductivity in the homogeneous regions and formation of superconducting clusters in the paths for the first time. Further, we develop an empirical relationship between the structural problems and transition temperatures to obtain a superconductor exhibiting the highest electrical and superconducting features.     

湍流扩散燃烧数值模拟中几种湍流模型的比较

为了比较湍流模型对火焰模拟结果的影响,应用CFD商业软件Fluent,对以C3H8为燃料,O2为氧化剂的火焰气相沉积法合成TiO2颗粒的火焰温度场进行数值模拟,通过对3种不同的湍流模型进行比较,发现标准κ-ω模型的结果与实验中的火焰相差很大,RSM模型并不能适用于所有的工况,而RNGκ-ε模型的温度场和火焰形状与实验中所观测到的结果吻合。     

Turbulent boundary layer

On the basis of a superposition model of turbulent eddies in contact with a solid wall, some new laws regarding the behavior of the turbulent boundary layer are established.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 1, pp. 39–46, July, 1980.     

Turbulent isentropic flows

Based the hypothesis that there is a direct proportional relationship between turbulent stresses and pairwise products of the averaged velocity components, isentropic flows are studied. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 2, pp. 330–335, January–February, 1998.     

Turbulent combustion of gaseous fuels

Differences and similarities between the parameters of turbulence and turbulent viscosity of an isothermic jet and a burning-fuel torch have been analyzed on the basis of experimental data. It is proposed to use the dependences obtained for calculating the temperature fields in torches of gaseous fuels.     

Plane Turbulent Couette Flow

The problem on plane turbulent Couette flow for an incompressible liquid has been solved based on the anisotropicturbulence model.     

Effect of impurities on SIMS

Results showing the effect of implantation of various species into copper on the secondary Cu⁺ ion signal are presented. Preliminary analysis indicates that both a physical change in the sample induced by the implantation and a chemical effect due to the presence of the implant species are responsible for the observed changes.     

Turbulent shear flow of micropolar fluids

Fundamental equations of turbulent flow of micropolar fluids are obtained employing the regular averaging technique. Turbulent stresses and couple stresses are discussed. The transfer of energy between the basic flow and turbulence is studied and various terms are identified. Prandtl theory of mixing length is extended to relate the turbulent stresses and couple stresses to the mean flow field. The special case of turbulent shear flow is treated in detail.     

Acoustic Excitation of Noncircular Turbulent Jets

Results of experimental investigation of turbulent mixing in jets flowing out of nozzles with different cross sections in the case of low and highfrequency acoustic excitation of the jets are presented. The influence of the shape of the cross section of a nozzle on the acousticexcitation sensitivity of a jet flowing out of it is analyzed.