喷射气举提升性能实验分析

由于传统气举提升效率较低,笔者设计出环形射流泵结构的喷射气举,建立了一套气举提升实验装置,选用精筛选的河沙作为提升对象,实验研究了进气量、浸入率等因素对喷射气举扬水量、扬固量的影响规律,对提升管内的流动形态进行了分析,并对传统气举和喷射气举的扬固能力进行对比;运用能量守恒定律建立了气举效率模型,对喷射气举和传统气举的扬固效率进行对比分析。结果表明：存在最优进气量,使喷射气举的扬固量和扬水量最高,浸入率越大,喷射气举的扬固量和扬水量越高,提升管内流动形态为团状流时能有效提升固液混合物;喷射气举扬固效率高于传统气举,在高进气量和低浸入率条件下尤为明显。     

Numerical Simulation of Turbulent Flow Flow Over a Tiny Rearward facing Step on Circular Cylinder

Results of numerical simulation for viscous incompressible turbulent flow field over a tiny rearward facing step on circular cylinder are presented.The Domain Subdividing and Matching method and the Simplified SOLA solution are engaged in the simulation. The effects of the step's height,installed position and Reynolds number on the flow field are obtained and discussed. The results show that, if the rearward facing step is installed on the cylinder surface at a suitable point, a reattached boundary layer will be produced at the downstream of the step lagged in a small distance on the cylinder s surface and will re separate from the cylinder s surface.The reattachment point and the re separated point will exchange as the step's height and installed point exchanging.There is an effective reattachment region. If the fluid flow separated from the sharp edge of the rearward step reattaches in the effective region, the re separated point will occur at the downstream of the cross section of the cylinder and the drag will be reduced. This pattern is not directly connected with the flow in laminar nor in turbulent.[WT5HZ]     

Extended theoretical analysis of jet and atomization under high-pressure spraying and collecting dust mechanism of droplet

The atomization model about interaction of cavitation, turbulence and aerodynamics is put forward through the analysis about the control equation of jet disturbance, the computed result of the dispersive jet equation, according to the conceptual model of spray based on two-phase flow. The action of cavitation and turbulence formed inside nozzle are thought to lead to the first atomization near the nozzle exit, while the aerodynamic effect controls the following second atomization process. And the critical Weber number 〖BP(〗［We］=12(1+1.077Oh1.5)〖BP)〗 is taken as the judgment index for occurring of the second atomization or not. The critical velocity for liquid splitting into droplets is 60 m/s according to the analysis of break mode about liquid drop, furthermore, jet fragmentation and film fragmentation occurs in the first and second atomization respectively. The typical mechanism of dust capture by water-cloud is improved through the active collision theory of droplet to dust particle. It is considered that an optimal relationship exists between collection rate and droplet size when gas containing dust is unsaturated and its temperature is higher than that of liquid, moreover, low fluid velocity can be propitious to the collection of tenuous droplet to exiguous dust on the basis of the same liquid-gas ratio and the same quantity of droplets.     

Numerical Analysis of Viscous Fluid Flow past a Circular Cylinder near a Plane with Boundary Element Method

The boundary element method was used for incompressible viscous fluid flow past a circular cylinder near a plane. The various phases of the flow passing the cylinder are studied numerically with different g/d. The numerical simulation of velocity fields is in good agreement with Davis' theoretical results and Taneda's experiments. In particular, the distributive curves of the surface force and the pressure on the circular cylinder were calculated numerically.     

The developing of the potential flow modelling of the burden flow in a blast furnace

Potential flow theory is an alternative theory to simulate burden flow in a blast furnace. But a contour line of the flow function defined to solve the old potential flow model isn’t a stream line. In this paper, the old potential flow model is first developed to a three-equation model which should include the equations of motion and continuity, and it is proved that the contour lines of the flow function defined to solve this three-equation model are stream lines. Second, an equation capable of calculating the distribution of diameter of burden particles in blast furnace is derived from an assumption that all burden particles on a stream line has the same diameter. Finally, the developed potential flow model and the derived equation are used to simulate a final reduction reactor producing hot metal containing Cr, together with other needed transportation equations. These works would play an important improving and exemplary role in the application of potential flow theory to simulate blast furnace process and other iron-making process.     

POD analysis of flow structures in thermally stratified flow in a confined space with the effects of horizontal wind

PIV measurements are carried out on the thermally stratified flows under different horizontal shear intensities in a confined space. Proper orthogonal decomposition (POD) is used to analyze the structures of these thermally stratified flows. Results show that, at the conditions without forced horizontal airflow, the low-order POD mode constitutes a high proportion of the total energy of the flow, and the horizontal flow is the dominant flow structure. The horizontal shear drives the energy to dissipate from large structure to smaller structures. Relative to the conditions without forced horizontal airflow, the ratios of vertical kinetic energy to horizontal kinetic energy become higher for each order of POD mode in the conditions with forced horizontal airflow. This indicates that horizontal shear can result in stratification instability and enhance the mass exchange in the vertical direction.     

射流器臭氧—水混合数值模拟及喉管优化

应用气液两相流动的双流体模型,数值模拟了射流器内臭氧—水的混合过程,得到了喉管内流场的参数分布,揭示了利用射流器进行臭氧—水混合的工作机理,为射流器结构参数优化设计和性能预测提供了有效手段。分析了最优喉管长度与面积比的关系,结果表明：最优喉管长度随着面积比的增大而增长,当面积比为2.25～6.25时,射流器的最佳喉管长度应在5.84～7.47d1之间。     

Investigation on the flow field in the connection sectionbetween two heat exchangers of a condensate gas water heater

This paper investigates a new type of condensate gas water heater,which consisted of a burner,a high temperature heater exchanger (i.e.rut exchanger) and a low temperature heater exchanger (i.e.subjoin exchanger or condensate exchanger).These components are set vertically one by one with a same rare plane.The subjoin exchanger is set at top and smaller in width than the rut exchanger and burner.A lean plane with some holes is set in the connect channel between the two exchangers aslant.As the flue gas flow crows the subjoin heater exchanger,the gas temperature will be below the dew point,and the same steam in the gas condensed into water.These blobs drip to the lean plane and are collected through the holes on the plane.The flow field of the connect channel and subjoin exchanger affected by the dip angle and holes distribution of the lean plane is investigated with CFD.The results show that there is a suitable configuration about the dip anger,hole's diameter and distribution of the lean plane.With that configuration,the flue gas can wash the tubes of the subjoin heat exchanger homogeneously in a higher velocity than the rut exchanger does.     

Indexes optimization of outburst forecast while a rock cross-cut coal is uncovered by pulsed water jet

To obtain the best outburst prediction index of rock cross-cut coal uncovering slotted by pulsed water jet,the effects of the rigidity coefficient’s measured value and the initial velocity of gas diffusion to the integrative indexes D and K are analyzed based on the dynamic evolution of coal crake field under water jet. Thus the integrative indexes D and K are excluded. A grey relation model of outburst prediction indexes(K1,S and P)from 7 coal mine’ rock cross-cut coal uncovering in Chongqing,Sichuan and Henan is set up. And the grey relation degrees of the 3 prediction indexes to outburst hazard are calculated by using grey relational analysis method. The results show that the outburst hazard can be more accurately reflected by the cuttings desorption index K1 when a cross-cut coal uncovering slotted by pulsed water jet,and it should be considered as the best outburst prediction index.     

Gain or loss of single chromosomes in wheat-rye addition lines and in 6x triticale detected by flow cytometry

Flow cytometric DNA analysis was used to study changes in nuclear DNA content induced by the gain or loss of chromosomes or chromosome arms in wheat-rye addition lines and in triticale. The amount of DNA present was determined by comparison with internal reference values obtained from euploid plants. The smallest difference in the DNA level which could be detected between aneuploid and euploid plants was 1.84%. Thus, it was possible to determine aneuploidy in all cases, except when very short telocentric rye chromosomes were added to wheat (addition line 1RS). The study has proved that flow cytometry is an efficient and simple way to discriminate between euploid and aneuploid plants in wheat and triticale.     

Investigation and application of jet aeration technology in the oxidation process of desulfurization slurry

The calcium sulfite oxidation rate is an important indicator to judge the efficiency of wet limestone/gypsum flue gas desulfurization process used by high-sulfur-coal power plant. Jet aeration technology which integrates aeration and stir into one apparatus is proposed to implement the forced oxidation of limestone/gypsum flue gas desulfurization in order to improve the oxidation rate. The working principle of jet aeration oxidation in desulfurization slurry is investigated. ANSYS CFX is used to simulate the flow field inside the desulfurization slurry tank and obtain the best installation method of jet aerator which makes the mixing and stirring effect of slurry ideal: 3 jet aerators are uniformly installed at the height of 0.8m up from the bottom of slurry tank with their axis perpendicular to the tank wall. The air suction flowrate of jet aerators is tested under the best installation method in the on-site application test of the X protection company of Chongqing. The oxidation rate of calcium sulfite in desulfurization slurry is also tested by using iodometric method. The results show that the total air suction flowrate of jet aerators is 59.52 m 3/h which meets the requirement of slurry oxidation air quantity and the oxidation rate of calcium sulfite in desulfurization slurry reaches 87.6% after two-hour oxidation by using jet aeration.     

Experiments and Numerical Simulation of Flow Distribution with Larger Flux in Multi-branch Pipe

Many heating process with smoking gas involves the uniformity problem of flow distribution with larger flux in multi-branch pipe. The authors do the experiments and numerical simulation of flow distribution with larger flux in multi-branch pipe, which gets flow regulation in distributing pipe and the methods to improve flow distribution uniformly. Experiments have shown that improving the frame of distributing pipe may realize the flow distribution uniformly to the pipe with larger flux and multi-branch.     

A new boundary treatment of lattice boltzmann method (LBM) for fully developed pressure-driven periodic incompressible fluid flow

This paper proposeds a new boundary treatment of Lattice Boltzmann Method (LBM) for fully developed pressure-driven periodic incompressible fluid flow. The pressure gradient, instead of equivalent body force, is applied to determine the particle distribution function on the periodic traverse sections for the fully developed pressure-driven periodic flow. Numerical simulations, including 2D pressure-driven poiseuille flow and fluid flow passing periodic square obstacles, are carried out using this new boundary treatment. Simulation results show that the proposed approach not only overcomes the nonphysical inlet and outlet flow disturbances (which the LBM simulation always suffers from using the existing pressure boundary methods), but also preserves the system periodicity and generates consistent pressure distribution with macroscopic periodic boundary conditions for the pressure-driven incompressible fluid flow.     

An investigation into the cause of sterility in double-flowered freesia varieties and the possibility of restoring fertility

Summary The sterility of double-flowered freesia is caused by the abnormal structure of the flower. It proved possible, by cultivation at higher temperatures, to induce fertile single flowers in a double-flowered variety. In winter, under natural light conditions, the most favourable temperature range is 18–20°C.In this way progeny can be obtained from seed and the application of the usual breeding methods to double-flowered freesias is made possible.     

Use of diploid self incompatible rose genotypes as a tool for gene flow analyses in roses

A diploid rose genotype previously found to be self incompatible in greenhouse pollination experiments was analyzed in order to investigate the capacity to self fertilize under field conditions. A subset of 36 plants from open pollinations were analyzed by means of AFLP markers. All plants were found to be the result of outcrossing events, thereby demonstrating the utility of these kinds of rose genotypes as effective pollen sinks for future gene flow analyses under field conditions. Furthermore, it was demonstrated that isolation distances of 250 m from large rose plantations are insufficient to prevent gene flow between populations.     

Simulation of thermocapillary flow in a two dimensional cavity with lattice Boltzmann method

Thermocapillary flow driven by an unbalanced surface tension plays the most important role for mass and heat transport in floating zone melt crystal growth under microgravity. The authors develop both a serial and a parallel codes with lattice Bhatnagar-Gross-Krook(BGK) model using two distribution functions, and numerically study the thermocapillary flow in a two dimensional square cavity with a single free surface under microgravity condition. The serial code is developed by combining collision and propagation step, using a temporary array to continuously read distribution functions, and its performance is improved two times faster than the code with separating the collision and propagation step. The MPI parallel code is proposed utilizing one dimensional partitioning and non-blocking communication. The accurate and reliable results are achieved with both the serial and parallel codes by comparing with CFD results simulated by the finite volume method; the MPI parallel code has high performance.     

四流T型中间包控流装置优化的水模拟分析

以某钢厂四流中间包为研究对象,根据相似原理建立了1∶3的物理模型。模型研究了不同结构的挡墙、导流孔和湍流抑制器对中间包内流动特性的影响。实验结果表明,“Y”型挡墙和梯形湍流抑制器(方案F)组合的控流装置能获得相对较优的实验结果。采用方案F的控流装置后,总体的死区比例从原型的23.69%降为8.02%,钢液能得到更为充分的混匀;各流平均停留时间的标准差从原型方案的23.56降低到7.34,各流一致性也得到了明显的改善。     

Numerical simulation of solid liquid flow of Yangtze River water in a semi annulus reentry tube

The flow of Yangtze River water in a semi annulus reentry tube was numerically simulated using a Eulerian Two phase Flow Model and computational fluid dynamics. The results show that, for Reynolds number Re=28×104, silt particles with representative diameter ds=0030 3 mm are separated in reentry tubes of all curvature (R/r) sizes, while silt particles with ds=0010 2 mm separate only slightly. Silt particles with ds=0108 5 mm, which posses a strong separation effect, are separated relatively less in reentry tubes of R/r=10~40 than in tubes with other R/r sizes.