露天矿坑飏尘防治用风障结构参数性能影响的模拟分析

Simulated analysis of the characteristic features of the windbreak structural parameters in the open-cut mining practice

基于某露天矿坑飏尘防治用风障工程建立数学和物理模型,探究风障结构参数对风障庇护效果的影响。运用正交试验原理和计算流体动力学软件Fluent对不同风障高度h、风障倾角α和风障厚度d的27组风障工况进行试验,并选取风障后相对平均风速及风障阻力作为考察指标,对试验结果进行直观分析及方差分析,得到不同风障结构因素对其庇护效果影响的显著性大小排序:风障厚度、风障倾角、风障高度。给出了优化型风障并分析了其后沿流水平距离变化时不同高度间相对风速的变化,得出在开孔率和高度相同时,直立风障的庇护效果与风障阻力和风障厚度呈正相关,并当厚度大于12.5mm时,风障庇护效果缓慢增强,风障阻力却迅速增大。

Taking an open-cut mine as our case study sample to prevent, shelter from or reduce the dust panicle emission, we have established a physical model as well as a numerical simulation for the wind-breaking structure while analyzing the shelter effects through the study of the structural parameters concerned. To begin with, we have picked up three normal structural parameters, i.e. the height, the thickness and the triangle, each of which is to be chosen for different values. Take the height of windbreak for instance, they are 20 m, 30 m and 40 m, respectively. At the same time, we have done 27 simulated experiments by using the computational fluid dynamics software known as Fluent in accordance with the principle of orthogonal tests. The above said simulations have been developed on the basis of SIM- PLE algorithm, on the standard k - ε model under high Re to enclose the general control equations. In our experiments, the simulated inlet wind speed u0 was supposed to be equal to 3 m/s, whereas the average relative speed after the windbreak （u/uo） and its pressure drop （△p0.4h）were taken as the tested indexes. In addition, we have analyzed the numerical simulation results, as shown in the tested indexes, so as to make clear the significance of the structural factors for protecting the effect in a great variance, because the structural factors influence the sheltering effect in three ways, as shown in thickness, triangle and height, from which we can deduce the optimized wind- break data in the form of A2B1 C2. To be exact, it will be possible for us to deduce the change of the relative flow speed at the different heights （0.2 h, 0.4 h, 0.6 h and 0.8 h）and deferent horizontal levels of windbreak A2B1 C2. That is to say, the nearer to the land surface, the better the shelter effect. Besides, it is also necessary to make clear the effect of thickness on the shelter. In this connection, we have chosen 6 different A2B1 C windbreak models to further our numerical simulations with six kinds of thicknesses, that is, 5.0 mm, 7.5 mm, 10.0 mm, 12.5 mm, 15.0 mm and 17.5 mm, which permits us to find the changes of relative flow velocities at different heights （0.2 h, 0.4 h, 0.6 h and 0.8 h）and horizontal levels of windbreak A2B1 C2. The above results show that the increase of the windbreak thickness helps to reduce the wind velocity, though the pressure drop around the windbreak is likely to rise. Particularly at the thickness of 12.5 mm, the wind-speed after the windbreak tends to slow down, though the pressure tends to drop sharply.