帕鲁特金矿通风在线监测系统建设与优化

针对帕鲁特金矿井下通风系统通风阻力过大、循环风严重、深部进风不足及风流调控不合理等问题,该研究提出了基于KJ973金属非金属矿山综合监控系统的井下通风在线监测系统建设方案,并基于该系统的监测数据制定矿井通风系统的优化方案,使用Ventsim软件数值模拟优化后的矿井通风系统,结果显示:优化后大部分风流经西风井送至深部采区,少部分风流经采区斜坡道向深部斜坡道流动,为井下各工作面风量的分配和调节提供可靠的数据支撑,同时为其他矿山在数字化建设和通风系统优化等方面提供了借鉴。

竖井型大长城市隧道火灾通风的数值模拟研究

随着城市建设发展,竖井型隧道越来越多地应用于城市交通隧道中。本文采用稳态与非稳态方法对火灾工况下竖井型隧道的气流场进行了数值模拟,分析了竖井型自然通风口对高温烟气扩散的影响。研究认为,竖井自然通风口引入隧道外冷空气,显著降低火源端部温度,可在一定程度上减少高温烟气对火源处隧道顶板的破坏。通过竖井引入新风,显著降低火源附近的有毒气体浓度,改善了火灾救援条件。火灾产生的有毒烟气由隧道洞口集中排放转变为竖井自然通风口分散排放,这对制定火灾救援、人员疏散方案有重要的指导作用。

并联双风机数值计算模型对隧道通风效果的影响

隧道通风射流风机的数值计算模型会影响计算结果,当双射流风机并联运行,需要考虑风机间相互影响时更需要研究射流风机模型对通风效果与风机工作状态的影响。本文通过风机测试与隧道通风测试分别验证了动态旋转风机模型与隧道通风射流模型的正确性,并研究了动态旋转风机模型与常用的稳态射流模型对整体隧道通风效果与风机运行工作状态的影响。通过比较了两者之间的差异,得出了动态旋转风机模型可以更好的模拟计算出风机后的瞬态射流流场、更好的计算出风机工作状态点的结论。

基于Fluent巷道断面平均风速点定位监测模拟研究

为了确定与巷道断面内平均风速相适应的风速传感器的安设位置,以保证巷道风量监测的准确性,利用Fluent软件在不同巷道类型、不同断面尺寸、不同风速的条件下,对24个矿井巷道模型的风流场进行了三维数值模拟,确定了巷道断面中轴线上与平均风速相等的点位,并得到了该点位置与巷道断面的关系,其中矩形巷道该点位置至顶板距离为巷道高度的11%～12%,半圆拱形巷道该点位置至顶板距离为巷道高度的15%～16%;同时,给出了平均风速位置查询表格和计算公式,并与实测结果比较,发现风速数据基本吻合,为矿井利用风速传感器准确监测巷道风量提供了有力保障。

毛细管辐射空调加置换通风系统在夏热冬冷地区应用可行性分析

本文分析了毛细管辐射空调加置换通风复合空调系统在夏热冬冷地区应用的可行性。并且对复合空调系统不同的送风方式进行数值模拟,得出在空调房间上置送风口的送风方式可以使空调房间气流更均匀的结论,同时这种送风方式也能更好地避免结露现象的产生。

自然通风与分层空调耦合运行的节能分析

自然通风及分层空调在大空间建筑中均有单独使用,而将两者结合使用的研究较少。本文应用FLUENT软件,对采用自然通风耦合分层空调方式下的室内热环境进行了数值模拟,并与单独采用分层空调方式进行比较。结果表明,采用耦合送风可以显著改善室内热环境,降低室内空调能耗,是大空间建筑节能的发展方向,值得深入研究。

Ventilation control of tunnel drilling dust based on numerical simulation

In order to control the dust pollution produced by air leg rock drill in the trolley area during the excavation of long-distance single ended tunnel,the full-scale physical model of working face was established by using FLUENT software,and the numerical simulation analysis of tunnel drilling ventilation and dust removal parameters was carried out.The results show that it is difficult to control the dust pollution of the face by conventional ventilation,and the drilling dust is distributed in the range of 10 m from the face;after the introduction of the long pressure and short suction ventilation scheme,when the ratio of compressed air volume to exhaust air volume is 0.72,the height of the pressure fan is 2.5 m,the distance between the pressure fan and the palm face is 20 m,and the exhaust fan is 12 m away from the palm,the dust concentration control efficiency of the working face is increased by about 60%.Therefore,in the similar long-distance single head tunnel construction,it is appropriate to adopt the dust removal method of long-distance short suction and exhaust fan to ensure the working environment.

Numerical simulation study of gob air leakage field and gas migration regularity in downlink ventilation

Aiming at the issue that mass of gas emission from mining gob and the gas exceeded in working face, gob air leakage field and gas migration regularity in downlink ventilation was studied. In consideration of the influence of natural wind pressure to analyze the stope face differential pressure, gob air leakage field distribution and gas migration regularity theoretically. Established a two-dimensional physical model with one source and one doab, and applied computational fluid dynamics analysis software Fluent to do numerical simulation, analyzed and contrasted to the areas of gob air leakage on size and gas emission from gob to working face on strength when using the downlink ventilation and uplink ventilation. When applied downward ventilation in stope face, the air leakage field of gob nearly working face, and the air leakage intensity were smaller than uplink, this can effectively reduce the gas emission from gob to working face; when used downlink ventilation, the air leakage airflow carry the lower amount of gas to doab than uplink ventilation, and more easily to mix the gas, reduced the possibility of gas accumulation in upper comer and the stratified flows, it can provide protection to mine with safe and effective production.

Numerical simulation of ventilation in blinding heading

The way of ventilation in all its forms and characteristics in the blinding heading was studied.On the basis of computational fluid dynamics (CFD) the turbulence model of restrained ventilation in blinding heading was set up,and the calculation boundary condi- tions were analyzed.According to the practice application the three-dimensional flow field of ventilation in blinding heading was simulated by the computational fluid dynamics soft- ware.The characteristics of the ventilation flow field such as the temperature field zone and the flow filed zone and the rule of the flow velocity were obtained.The ventilation in blinding heading under certain circumstances was calculated and simulated for optimiza- tion.The optimal ventilation form and related parameters under given condition were ob- tained.The rule of the ventilation in blinding heading was theoretical analyzed,which pro- vided reference for the research on the process of mass transfer,the rule of hazardous substances transportation and ventilation efficiency,provided a new method for the study of reasonable and effective ventilation in blinding heading.

Simulation on dissolute and dust dispersion in comprehensive mechanized heading face with forced-exhaust ventilation

According to the characteristics of comprehensive mechanized heading face, established the mathematical model of single-phase air flow with κ-ε two equations model, and have established κ-ε-θ-κp mathematic model to solve two-phase flow of gas and particles in dust space with eulerian-eulerian method and eulerian-lagrangian method. Numerical solution of gas-particle two-phase flow was put forward based on collocated grid SIMPLE algorithm. Moreover, numerical simulation of dust concentration in fully mechanized caving face was carded out by using Fluent software. Finally, when in forced-exhaust ventilation circumstance, drawer type fan drum have less dust absorption, and most of dust spread to the other site; the dust concentration is inversely proportional to the distance from tunneling head, and the dust concentration has already diffused to decrease below 102 mg/m3 at the position ofx=12 m. Dust are more focused on relative side（in the range about y from 0 to 2 meter） of roadway space of press-ventilated fan drum, especially between tunneling place and drawer type fan drum; the roadway with road header have a higher dust concentration. These conclusions provide reliable theory basis for the dust prevention in comprehensive mechanized heading face.

Particle deposition in ventilation duct with convex or concave wall cavity

A numerical study is carried out on particle deposition in ducts with either convex or concave wall cavity.Results show that,if compared with smooth duct,particle deposition velocitiesVd^+increase greatly in ducts with wall cavities.More specifically,forτ+<1,Vd^+increase by about 2–4 orders of magnitude in the cases with the convex and concave wall cavities;forτ+>1,Vd^+grows relatively slower.Enhancement of particle deposition with wall cavities is caused by the following mechanisms,i.e.,interception by the wall cavities,expanded deposition area,and the enhanced flow turbulence.In general,addition of wall cavities is contributive for particle deposition,so it provides an efficient approach to remove particles,especially with small size,e.g.,PM2.5.Moreover,the convex wall cavity leads to a larger increment ofVd^+than the concave wall cavity.However,taking pressure loss into account,thoughVd^+is relatively lower,duct with the concave wall cavity is more efficient than that with the convex wall cavity.

Multi-factor influence of cross-sectional airflow distribution in roadway with rough roof

The wall surface roughness renders a significant impact on ventilation of roadways and cross-sectional wind speed distribution.Herein,the wall roughness(Ra)in the roadway has been defined theoretically.Moreover,three-center arched roadway models for different situations are established based on the normal distribution of roof roughness.The influence of inlet velocity,roof roughness and roadway height on wind speed distribution is systematically studied by using Fluent software.At Ra=0.1 m,the simulation results reveal that the wind speed is negatively related to the distance from the wall to the point where 80%of the central wind speed is reached(DA).Also,the wind speed distribution is significantly influenced by increasing the roof roughness.However,the wind speed distribution becomes asymmetric at Ra=0.2 m and 0.3 m.Furthermore,the low-speed area(v≤1 m/s)started to concentrate on the roof with the increase of roadway height.Overall,an Ra value of<0.1 m can reduce the influence of wall roughness on wind speed distribution of the roadway,which is suggested in practical applications.

Numerical Modeling and Analysis of Gas Entrainment for the Ventilated Cavity in Vertical Pipe

A semi-empirical gas entrainment model was proposed for the ventilated cavity in vertical pipe, based on which, a complete numerical scheme was established by coupling with the Eulerian-Eulerian two-fluid model to predict the multiscale flow field created by ventilated cavity. Model predictions were validated against experimental measurements on void fraction and bubble size distributions. Simulations were carried out to explore the effect of ventilation rate and inlet turbulence intensity on the macroscale cavity shape and the bubbly flow downstream of the ventilated cavity. As the ventilation rate increasing, a reverse trend was observed for the void fraction and bub-ble size distributions. It is concluded that the average void fraction in the pipe flow region is determined by the vo-lumetric ratio between liquid and gas. However, the bubble size evolution is dominated by the breakage effect induced by turbulence in the vortex region. Furthermore, simulations were conducted to analyze geometric scale effect based upon Froude similitude. The results imply that the velocity distributions were properly scaled. Slight scale effect was seen for the void fraction caused by faster dispersion of bubbles in the larger size model. The comparatively greater bubble size was predicted in the smaller model, implying significant scale effects in terms of tur-bulence and surface tension effect. It reveals that empirical correlations valid in wide range are required for the extrapolation from small-size laboratory models.

Numerical investigation of turbulent bubbly wakes created by the ventilated partial cavity

This paper presents a numerical study on the turbulent bubbly wakes created by the ventilated partial cavity.A semi-empirical approach is introduced to model the discrete interface of the ventilated cavity and its complex gas leakage rate induced by the local turbulent shear stress.Based on the Eulerian-Eulerian two-fluid modeling framework,a population balance approach based on MUltiple-SIze-Group (MUSIG) model is incorporated to simulate the size evolution of the sheared off microbubbles and its complex interactions with the two-phase flow structure in the wake region.Numerical predictions at various axial locations downstream of the test body were in satisfactory agreement with the experimental measurements.The captured bubbly wake structure illustrates that the bubbles may disperse as a twin-vortex tube driven by gravity effect.The predicted Sauter mean bubble diameter has confirmed the dominance of the coleascense process in the axial direction.As the bubbles develop downstream,the coleascense and breakup rate gradually reach balance,resulting in the stable bubble diameter.A close examination of the flow structures,gas void fraction distributions and the bubble size evolution provides valuable insights into the complex physical phenomenon induced by ventilated cavity.