Overlying strata movement of recovering standing pillars with solid backfilling by physical simulation

To analyze the overlying strata movement law of recovering room mining standing pillars with solid backfilling.Physical simulation experiments with sponge and wood as the backfilling simulation material were tested.The results show that:(i) The covering-rock mechanics of the overly strata comes from "two-arch structures + hinged girder + bend beam" to "backfilling material + hinged girder + bent beam" by increasing the fill ratio from 0%to 85%,the beginning of overlying strata movement appears later and the total duration of subsidence velocity increased from zero to the highest value increases.The trend of "single polarization" of the subsidence velocity curves becomes noticeable and the velocity variation trend becomes stable,(ii) The equiponderate aeolian sand was added to improve the anti-pressure ability of the loess,and the corresponding ground processing & transportation system was designed.

Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis

A coupled intravascular-transvascular-interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network. This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels. Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille＇s law and Darcy＇s law, respectively, transvascular flow is described by Starling＇s law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convection on the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.

Wind tunnel simulation of wind loading on a solid structure of revolution

The wind tunnel simulations of wind loading on a solid structure of revolution with one smooth and five rough surfaces were conducted using wind tunnel tests. Timemean and fluctuating pressure distributions on the surface were obtained, and the relationships between the roughness Reynolds number and pressure distributions were analyzed and discussed. The results show that increasing the surface roughness can significantly affect the pressure distribution, and the roughness Reynolds numbers play an important role in the change of flow patterns. The three flow patterns of subcritical, critical and supercritical flows can be classified based on the changing patterns of both the mean and the fluctuating pressure distributions. The present study suggests that the wind tunnel results obtained in the supercritical pattern reflect more closely those of full-scale solid structure of revolution at the designed wind speed.

Effects of Rotor Solidity on the Performance of Impulse Turbine for OWC Wave Energy Converter

Impulse turbine, working as a typical self-rectifying turbine, is recently utilized for the oscillating water column（OWC） wave energy converters, which can rotate in the same direction under the bi-directional air flows. A numerical model established in Fluent is validated by the corresponding experimental results. The flow fields, pressure distribution and dimensionless evaluating coefficients can be calculated and analyzed. Effects of the rotor solidity varying with the change of blade number are investigated and the suitable solidity value is recommended for different flow coefficients.

Controlling Roll Temperature by Fluid-Solid Coupled Heat Transfer

Currently, when magnesium alloy sheet is rolled, the method of controlling roll temperature is simple and inaccurate. Furthermore, roll temperature has a large influence on the quality of magnesium alloy sheet; therefore, a new model using circular fluid flow control roll temperature has been designed. A fluid heat transfer structure was designed, the heat transfer process model of the fluid heating roll was simplified, and the finite di erence method was used to cal?culate the heat transfer process. Fluent software was used to simulate the fluid?solid coupling heat transfer, and both the trend and regularity of the temperature field in the heat transfer process were identified. The results show that the heating e ciency was much higher than traditional heating methods(when the fluid heat of the roll and tempera?ture distribution of the roll surface was more uniform). Moreover, there was a bigger temperature di erence between the input and the output, and after using reverse flow the temperature di erence decreased. The axial and circum?ferential temperature distributions along the sheet were uniform. Both theoretical calculation results and numerical simulation results of the heat transfer between fluid and roll were compared. The error was 1.8%–12.3%, showing that the theoretical model can both forecast and regulate the temperature of the roll(for magnesium alloy sheets) in the rolling process.

Construction and stability of an extra-large section chamber in solid backfill mining

In solid backfill mining without gangue removal, the gangue is separated directly underground and backfilled into goaf. This necessitates the underground construction of an extra-large section chamber for separation equipments. For the construction of an extra-large section chamber in the Tangshan mine, we proposed an active support through a combination of bolting, anchor cables, lining, and a reinforced chamber floor by inverted arch pouring. ABAQUS software was used to analyze the surrounding rock deformation and the plastic zone development of the chamber under different excavation schemes.The best excavation scheme was determined, and the effectiveness of the combined supports was verified. In practice, the engineering installation showed good overall control of the movement of the surrounding rock, with roof-to-floor and side-to-side convergences of 154.6 and 77.5 mm, respectively,which meets the requirements for underground coal gangue separation.

Gateside packwall design in solid backfill mining-A case study

Based upon characteristic movement features of the overlying strata in solid backfill mining and in-situ observations,an associated model representing a roadway support system has been developed.Based on the Winkler foundation and beam model,the current study presents a static analysis of the model,thus permitting acquisition of a theoretical formula pertaining to roof convergence.Through use of working face 6304-1(Jisan Colliery) as the research setting,the association between roof convergence magnitude and both packwall strength and width have been elucidated.Based upon observed conditions at the working face,realistic packwall parameters have been formulated,with numerical simulation results and field application results indicating that design parameters garnered from the developed formula successfully adapted to local geological movement and deformation.Accordingly,roadway deformation was shown to be within the permissible range,thus satisfying mine production requirements.The proposed method in the current study may give a design basis for pack design in the context of SBM under similar conditions.

Numerical simulation of flow hydrodynamics of struvite pellets in a liquid–solid fluidized bed

Phosphorus recovery in the form of struvite has been aroused in recent decades for its dual advantages in eutrophication control and resource protection.The usage of the struvite products is normally determined by the size which is largely depended on the hydrodynamics.In this study,flow behavior of struvite pellets was simulated by means of Eulerian–Eulerian two-fluid model combining with kinetic theory of granular flow in a liquid–solid fluidized bed reactor（FBR）.A parametric study including the mesh size,time step,discretization strategy,turbulent model and drag model was first developed,followed by the evaluations of crucial operational conditions,particle characteristics and reactor shapes.The results showed that a cold model with the mesh resolution of 16 × 240,default time step of 0.001 sec and first order discretization scheme was accurate enough to describe the fluidization.The struvite holdup profile using Syamlal–O＇Brien drag model was best fitted to the experimental data as compared with other drag models and the empirical Richardson–Zaki equation.Regarding the model evaluation,it showed that liquid velocity and particle size played important roles on both solid holdups and velocities.The reactor diameter only influenced the solid velocity while the static bed height almost took no effect.These results are direct and can be applied to guide the operation and process control of the struvite fluidization.Moreover,the model parameters can also be used as the basic settings in further crystallization simulations.

RFID天线薄膜静态变形的有限元仿真及试验研究

文中通过Solid Works Simulation有限元分析,计算了RFID天线薄膜在不同载荷和伸出长度情况下的变形量;同时搭建视觉检测试验设备,经视觉测量得到RFID天线薄膜在不同载荷和伸出长度下的变形量。综合计算结果和试验结果,发现两者在数据上基本吻合,变化趋势一致。

The ultimate goal of modeling—Simulation of system and plant performance

Modern production processes in chemical, pharmaceutical and biological industries are characterized by complex process structures, which consist of different apparatuses and process steps. Modeling the entire process requires simulating all units altogether, while taking into account interconnections between them, Nevertheless, in the area of solids processing, there is nowadays an unfilled gap from the side of computer support of process modeling in allowing effective optimization and prediction of the behavior of the whole plant, This paper presents a tool for flowsheet simulation which allows the simulation of the stationary behavior of complex processes dealing with solids and its extension towards dynamic modeling, Also, a new simulation concept is proposed on the basis of the multiscale approach. On the macroscale, fiowsheet simulation is performed with the help of the SolidSim system. Parameters for the macromodels in Solid-Sim are predicted by microscale simulation. The models for the two scales are then coupled by inter-scale communication laws. Application of the proposed modeling concept is shown by an example of fluidized bed granulation.

Thermo-elasto-hydrodynamic analysis of a specific multi-layer gas foil thrust bearing under thermal-fluid–solid coupling

Gas foil bearing faces severe and complex thermal-fluid–solid coupling issues when in ultra-high speed and miniaturized impeller machineries.In this study,a Thermo-Elasto-Hydrodynamic(TEHD)analysis of a specific multi-layer gas foil thrust bearing on the continuous loading process within a steady rotational speed is numerically investigated by a three-dimensional thermal-fluid–solid coupling method.Results indicate that the multi-layer foil exhibits nonlinear overall stiffness,with the thrust bottom foil serving as the primary elastic deformation structure,while the thrust top foil maintains a well-defined aerodynamic shape during a loading process,which helps reduce frictional damage and achieve an adequate loading capacity.For low loads,the fluctuation of the gas film is extremely sensitive,and it weakens dramatically as the load increases.The viscous heating and friction torque exhibit a linear relationship with an increasing bearing load after a rapid growth.Depending on the exact stacking sequence and contact position of the multi-layer gas foil,the overlapping configuration allows for efficient transfer of viscous-shearing heat accumulated at the smallest air film through thermal conduction while providing elastic support.Due to the strong inhomogeneity of the viscous heat under varying loads,the temperature distribution on the top foil surface shows pronounced variations,while the difference between the peak and average temperatures of the thrust plate and top foil surfaces widens substantially with an increasing load.

Investigation on the application of reformed coke oven gas in direct reduction iron production with a mathematical model

To investigate the application of reformed coke oven gas （COG） in producing the direct reduction iron （DRI）, we simulated a countercurrent gas solid moving bed reactor in which the iron ore pellet was reduced by reformed COG. An ordinary differential equation （ODE） was set based on the unreacted shrinking core model considering both mass and energy balances of the reactor. The concentration and temperature profiles of all species within the reactor were obtained by solving the ODE sys tem. The solid conversion and gas utilization were studied by changing gas flow rate, solid flow rate, reactor length, and the ratio of O/CHa to guide the practical application of COG in DRI production. Model results showed that COG was suitable for the DRI production. In order to meet the requirement of the industrial production, the minimum gas flow rate was set as 130,000 Nm3/h, and the maximum production was 90 t/h. The reactor length and the mole ratio x（O）： x（CH4） were depended on the actual industrial situations.