障碍物位置对瓦斯爆炸火焰传播影响的数值模拟

利用计算流体动力学软件FLUENT研究了受限空间内平行障碍物和交错障碍物对火焰形状的影响.模拟采用500mm×150mm二维矩形空间模型,计算了2个平行障碍物、2个交错障碍物、3个平行障碍物、3个交错障碍物等4种工况下的火焰发展过程.障碍物间距100 mm,阻塞率为0.5.选取k-epsilon Realizable湍流模型,P1辐射模型和涡耗散模型模拟瓦斯爆炸火焰传播.模拟结果表明:受到交错障碍物影响,10ms处已经出现明显的火焰湍流,且交错障碍物具有更大的预热区面积.火焰传播过程与实验相近,模拟结果可靠,为进一步利用数值模拟方法研究瓦斯爆炸相关内容提供了参考.     

瓦斯爆炸运动火焰生成压力波的数值模拟

从三维N-S方程出发，用TVD格式，对瓦斯爆炸过程中火焰产生压力波的过程进行了数值模拟，在此基础上，模拟了氢氧燃烧驱动的破膜过程以及破膜前后压缩波、稀疏波对火焰阵面的影响，同时，也研究了瓦斯爆炸过程中，压力波、火焰与障碍物的相互作用，数值模拟结果与理论分析吻合较好，从而进一步验证了该程序能处理含有化学反应和复杂管道的预混可燃气体爆炸问题。     

湍流的诱导及对瓦斯爆炸火焰传播的作用

对巷道面积突变和巷道分叉对瓦斯爆炸过程中火焰传播速度的影响进行了试验研究。并利用加速环研究了巷道支架对瓦斯爆炸传播规律的影响，在此基础上对湍流的形成过程进行了理论分析。研究结果表明，管路分叉，面积突变对瓦斯爆炸过程中火焰传播规律有重要影响，导致产生附加湍流，使瓦斯爆炸过程中火焰的传播速度迅速增大；在管道内装加速环，将使瓦斯爆炸过程中湍流度加剧，火焰的传播速度更大，激波生成的位置。最大点位置前移。强度增大，研究结果对指导现场防治瓦斯爆炸和减轻瓦斯爆炸的威力具有重要作用。     

障碍物对瓦斯爆炸过程中火焰和爆炸波的影响

对瓦斯爆炸过程中障碍物对火焰和爆炸波的影响进行了试验研究．结果表明,障碍物对瓦斯爆炸过程中产生的火焰和爆炸波具有重要影响．有障碍物存在时,火焰的传播速度将迅速提高,在２０倍长径比处达到最大值,随后逐渐衰减,直至熄灭．原因是障碍物的存在加剧了火焰传播过程中的湍流现象,而湍流又加速了火焰传播．障碍物的存在使爆炸波的传播曲线变化幅度迅速增大,并可能产生突变界面和马赫数Ｍ≥１的情况,即产生激波,从而增大瓦斯爆炸的威力．因此,应尽量减少矿井巷道中的障碍物．     

交错障碍物对瓦斯爆炸影响的实验研究

为了研究交错障碍物对瓦斯爆炸火焰形状、火焰速度及爆炸压力的影响,设计并搭建了150mm×150mm×500mm半封闭透明腔体的瓦斯爆炸实验台,采用化学当量比浓度的甲烷-空气预混气体,并与平行障碍物工况进行了比较.实验结果表明:与平行障碍物相比,交错障碍物明显增强了火焰形变,提高了火焰速度和爆炸压力,其中火焰速度和爆炸压力的提升率最高分别达到78.0%和198%.因此,在实际巷道中,应尽量避免障碍物的交错放置.     

不同间距障碍物下瓦斯爆炸特性的实验研究

利用自建的模拟煤矿巷道的水平管道式气体爆炸实验系统,在置障条件下对瓦斯爆炸特性进行实验研究,改变内置障碍物的间距,研究其对瓦斯爆炸压力及火焰传播速度的影响规律.结果表明:瓦斯爆炸压力随着障碍物间距的增加呈现缓慢递增的变化规律;而火焰传播速度也随着障碍物间距的增加而递增.总体来说,障碍物间距的改变对爆炸压力的影响程度比其对火焰传播速度的影响要小一些.     

环形障碍物对瓦斯爆炸影响的实验研究

研究障碍物对瓦斯爆炸的影响,对预防和减小煤矿巷道内的瓦斯爆炸危害具有重要意义.利用长径比约为70的水平管道式爆炸实验装置,在常温常压下研究环形障碍物的数量、阻塞率和间距对瓦斯爆炸特性的影响.结果表明:障碍物的存在对瓦斯爆炸具有激励作用,其中障碍物的数量和阻塞率激励效果明显,而间距对其影响较小.研究结果对于预防和控制瓦斯...     

瓦斯爆炸过程中火焰厚度的实验室测定及其分析

实验探讨了瓦斯爆炸过程中火焰厚度变化特性及障碍物、膜片位置和压力等的影响。结果表明,障碍物和膜片对瓦斯爆炸过程中火焰厚度具有重要影响。当有障碍物存在时,瓦斯爆炸过程中产生的火焰厚度常常会小于无障碍物存在时所产生的火焰厚度;膜片距离源较近时,火焰厚度明显增大,火焰厚度越大,在其传播过程中对传播途径上的可燃物的点燃作用越大。研究结果对指导现场防治瓦斯爆炸、减轻瓦斯爆炸灾害具有一定的指导意义。     

瓦斯爆炸过程中火焰传播规律的模拟研究

在模拟实验和数值计算的基础上 ,研究了瓦斯爆炸过程中火焰传播规律及其加速机理 .研究结果表明 ,障碍物对瓦斯爆炸过程中火焰传播规律有重要影响 .障碍物的存在将使瓦斯爆炸过程中火焰的传播速度迅速提高 .瓦斯爆炸时 ,火焰阵面附近温度较高 ,阵面前附近区域温度梯度变化较大 ,阵面后区域的温度变化较小 .障碍物附近温度很快上升到最大值 ,然后由于化学反应结束及管道壁吸热 ,温度开始下降 .在火焰传播通道上设置的障碍物对气相火焰具有加速作用 ,加速作用的机理主要是由于障碍物诱导的湍流区对燃烧过程的正反馈造成的     

壁面粗糙度对瓦斯爆炸火焰波传播的影响

在实验研究的基础上，分析了壁面粗糙度对瓦斯爆炸过程中火焰传播规律的重要影响．研究结果表明，壁面粗糙度对瓦斯爆炸过程的影响很大，相比光滑管道，粗糙管的火焰速度大幅度提高；对于管道终端闭口系统和开口系统的瓦斯爆炸过程，壁面粗糙度对两种系统的影响规律是一致的，影响程度比较接近．基于壁面粗糙度对瓦斯爆炸影响的实验结论，从理论上分析了壁面粗糙度对高速传播的火焰区的影响，并对实验现象做出了合理解释．因此，在矿井开拓中，应尽可能减小巷道壁面的粗糙度．研究结果对指导现场如何防治瓦斯爆炸，减轻瓦斯爆炸的威力具有重要作用．     

受限空间瓦斯爆炸火焰与毒气传播研究

为揭示瓦斯爆炸过程中火焰、毒气及压力三者间相互关系,采用一端封闭的爆炸试验装置,通过改变瓦斯聚集长度和点火强度,研究了瓦斯爆轰及爆燃状态下火焰、毒气及压力传播变化规律.结果表明,管道内瓦斯爆燃状态下火焰的传播速度远小于爆轰状态下的传播速度,变化趋势呈线性;瓦斯爆炸火焰传播速度的大小直接影响爆轰的形成以及爆炸强度和爆炸传播距离;爆燃状态下火焰和毒气传播的距离基本相当,均为原始瓦斯聚集总长度的2倍左右;爆轰状态下火焰和毒气传播的距离基本相当,均大于原始瓦斯聚集长度,但传播距离不确定.     

Numerical simulation for explosion wave propagation of combustible mixture gas

A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code,Young’s technique was employed to track the interface between the explosion products and air,and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct,for point initiation,the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall,multi-peak values appear on pressure—time curve,and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct,explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products,and indicate that the ignition model and multi-material interface treatment method are feasible.     

Numerical simulation of non-contact explosion by door breaching explosive

Aiming at the estimation of personal injury attached by counter-terrorist door breaching explosive blast wave,according to the actual scene,four typical application space models of counter-terrorist door breaching explosives are established,and numerical simulation of air-blast wave propagation by non-contact explosion counter-terrorist door breaching explosive are achieved. The research results show that the overpressure behind the target door is attenuated deeply through the burglary resistant safety door,and the propagation of blast wave and the damage effect under different space conditions are obviously different.     

Development of SOM combustion model for Reynolds-averaged and large-eddy simulation of turbulent combustion and its validation by DNS

The derivation and closure methods of the second-order moment (SOM) combustion model are proposed. The application of this model to Reynolds averaged (RANS) and large-eddy simulation (LES) of turbulent swirling diffusion combustion, jet diffusion combustion, and bluff-body stabilized premixed combustion is summarized. It is indicated that the SOM model is much better than the eddy-beak-up (EBU) and presumed PDF models widely used in commercial software and engineering. The SOM modeling results are close to those obtained using the most accurate but much more complex PDF equation model. Moreover, it can save much more computation time than the PDF equation model. Finally, the SOM model is validated by the direct numerical simulation (DNS) of turbulent reacting channel flows. Supported by the National Natural Science Foundation of China (Grant Nos. 50606026 and 50736006), and the National Basic Research Program of China (“973”) (Grant No. G-1999-0222-07)     

防爆紫外火焰探测器的应用

文章结合PPG芜湖厂防爆紫外火焰探测器的安装工程实例,探讨了防爆紫外火焰探测器在甲类化工厂房及高危行业的应用。     

Effect of variation in gas distribution on explosion propagation characteristics in coal mines

In order to investigate the effect of variation in the distribution of gas on explosion propagation characteristics in coal mines, experiments were carried out in two different channels with variation in gas concentration and geometry. Flame and pressure transducers were used to track the explosion front velocity. The flame speed (Sf) showed a slight downward trend while the methane concentration varied from 10% to 3% in the experimental channel. The peak overpressure (Pmax) dropped dramatically when com-pared with normal conditions. As well, the values of Pmax and Sf decreased when the methane concentration dropped from 8% to 6%. The flame speed in the channel, connected to a cylinder with a length varying from 0.5 to 2 m, was greater than that in the normal channel. The peak overpressure was also higher than that under normal conditions because of a higher flame speed and stronger pressure piling up. The values of Pmax and Sf increased with an increase in cylinder length. The research results indicate that damage caused by explosions can be reduced by decreasing the gas concentration, which should be immediately detected in roadways with large cross-sections because of the possibility of greater destruction caused by more serious explosions.     

半封闭受限空间煤尘与瓦斯耦合爆炸研究

煤尘参与的瓦斯爆炸事故具有很强的破坏性和伤害性,是煤矿的重大事故之一.用一端开口的半封闭管道爆炸实验装置,通过改变瓦斯与煤尘耦合爆炸浓度及点火条件,揭示受限空间瓦斯与煤尘耦合爆炸的规律.实验结果表明,封闭下的耦合体爆炸火焰传播速度较开口状态达到极值快,但极值点距点火位置较近,开口爆炸火焰传播距离是积聚耦合体长度的2倍左右;瓦斯参与的煤尘爆炸,爆炸相对强度随瓦斯浓度的增加而增加,传播距离更远;理论推导瓦斯与煤尘耦合爆炸超压传播距离与爆炸能量的平方根成正比,与巷道断面积的平方根成反比,研究结果为防治瓦斯爆炸、事故勘验以及阻隔爆装置的研制提供了可靠的实验数据.     

超细水雾抑制瓦斯燃烧火焰的实验研究

通过搭建模拟回采工作面小尺寸实验平台,利用改造后的家用燃气灶作为燃烧器,研究了可燃预混气体火焰在超细水雾作用下火焰的变化过程,并测得了超细水雾作用于火焰过程中火焰的温度.通过改变通风速度和超细水雾的雾化速率,揭示了可燃预混气体在超细水雾氛围中火焰与温度的变化规律.通过建立稳定火焰面的力和速度平衡,找出了火焰形状拉伸扭曲的原因是破坏了火焰外焰和热气层交界面上力和速度的平衡;在其他条件一定的情况下,向模拟工作面上施加超细水雾后,火焰周围流场扰动明显增大,与在单独通风条件下相比,火焰温度跳动变化幅度和频率增大;在保证超细水雾质量浓度不变条件下,通风速度越大,则混合气体扰动越大,温度的跳动就越大,火焰的燃烧就越不稳定.实验结果表明超细水雾能很好地抑制瓦斯火焰的燃烧.