防爆柴油机排气阻火器流场分析及结构改进

发布时间：2018-03-08 20:34

本文选题：防爆柴油机　切入点：排气系统　出处：《中北大学》2015年硕士论文　论文类型：学位论文

【摘要】：防爆柴油机排气系统主要由排气歧管、排气波纹管、废气处理装置、阻火器和排气管组成。其中，排气阻火器是保证防爆柴油机隔爆性能的必备装置，能防止排气系统回火、窜火，但同时会使排气背压上升，严重影响防爆柴油机的排气性能；因此，研究阻火器的流场与结构形式，对提高防爆柴油机的综合性能具有实际工程意义。本文针对6100防爆柴油机排气阻火器进行研究，在保证隔爆能力的基础上，从降低排气阻力的角度出发，，设计了一款结构新型的阻火器，主要研究内容和成果如下：（1）对近十年来国内外的阻火器专利信息进行了分析，了解当前国内外阻火器的先进技术、理论，并由此对阻火器未来的发展方向做出预测。（2）对平板阻火器隔爆实验做数值仿真，验证了本文所用的计算方法的可行性。通过对实验装置的几何模型做适当简化，采用GAMBIT建立其二维模型；通过FLUENT对网格做独立性分析，结合实际情况确定了定解条件，对封闭系统内甲烷/空气预混气体的点燃及爆炸过程进行模拟，将模拟结果与实验计算进行对比，结果发现，二者大致相符，说明本文所采用的数值计算方法是可行的。（3）对平板阻火器及波纹阻火器内部流场进行模拟，比较不同结构形式阻火器的隔爆性能与流通能力，获得结构形式对阻火器性能的影响规律：阻火器狭缝尺寸越大、自由面积率越高，隔爆性能便越差；火焰的淬熄距离与阻火器的自由面积率不成线性关系；阻火器流通能力的优劣正好跟它的隔爆性能相反，二者此消彼长，相互矛盾。（4）参考SCR催化器载体的结构提出方格孔阻火器，并对其做流场分析；为方格孔阻火层确定相关尺寸，利用流固耦合方法，算出气流经过阻火器时栅栏片的变形量，并根据煤炭行业的相关规定：栅栏片的平面度不能大于0.15mm，确定栅栏片的厚度为0.4mm；对方格孔做流场分析，要求方格孔须满足隔爆性能，并尽量降低排气阻力，按这两个要求确定方格孔的尺寸为1.2mm×1.2mm，阻火器在气流方向上的厚度为65mm。（5）对最终设计好的方格孔阻火器做三维流场分析，并与平板式、波纹式阻火器的性能进行比较，最终发现，方格孔阻火器阻火性能与波纹阻火器的相差无几，且流通性能要优于波纹阻火器的流通性能。本文设计的方格孔阻火器，参考了SCR催化器载体的结构，这也意味着，催化器载体经过适当的调整后也可具备隔爆能力。因此，本文的研究，使催化器与阻火器实现一体化成为可能，从而可精简防爆柴油机排气系统组成，降低排气阻力，达到提高防爆柴油机性能的目的，这对防爆柴油机的防爆技术及尾气的净化均有理论与工程意义。
[Abstract]:The exhaust system of explosion-proof diesel engine is mainly composed of exhaust manifold, exhaust corrugated tube, exhaust gas treatment device, fire arrester and exhaust pipe. But at the same time, the exhaust back pressure will rise, and the exhaust performance of explosion-proof diesel engine will be seriously affected. Therefore, the flow field and structure of the igniter are studied. It is of practical engineering significance to improve the comprehensive performance of explosion-proof diesel engine. In this paper, the exhaust arrester of 6100 explosion-proof diesel engine is studied. On the basis of ensuring the flameproof capability, the exhaust resistance is reduced. A new type of fire arrester is designed. The main research contents and results are as follows:. This paper analyzes the patent information of fire arresters at home and abroad in recent ten years, and finds out the advanced technology and theory of fire arresters at home and abroad, and predicts the future development direction of fire arresters. 2) numerical simulation on flameproof flat-plate fire arrester is made, which verifies the feasibility of the calculation method used in this paper. Through the proper simplification of the geometric model of the experimental device, the two-dimensional model is established by using GAMBIT, and the independence of the mesh is analyzed by FLUENT. Combined with the actual situation, the conditions of the fixed solution are determined, and the ignition and explosion process of the methane / air premixed gas in the closed system is simulated. The simulation results are compared with the experimental calculation. It is found that the results are roughly consistent with each other. It is shown that the numerical method used in this paper is feasible. 3) the internal flow field of flat and corrugated fire arresters is simulated, and the flameproof performance and circulation ability of different structural types are compared. The influence of structural forms on the performance of fire arresters is obtained: the bigger the slit size is, The higher the free area ratio is, the worse the flameproof performance is. The quenching distance of flame does not have a linear relationship with the free area ratio of the flame arrester. The flow ability of the flame arrester is just opposite to its flameproof performance. (4) referring to the structure of the carrier of SCR catalytic converters, this paper puts forward a grid pore arrester and analyzes its flow field, determines the relevant dimensions for the square hole fire arrester layer, and calculates the deformation of the palisade when the airflow passes through the arrester by using the fluid-solid coupling method. According to the relevant regulations of the coal industry, the planeness of the palisade plate can not be greater than 0.15 mm, and the thickness of the palisade slice is determined to be 0.4mm.The flow field analysis of the other hole requires that the square hole must meet the flameproof performance and reduce the exhaust resistance as far as possible. According to these two requirements, the size of the square hole is 1.2mm 脳 1.2mm, and the thickness of the igniter in the direction of air flow is 65mm. Finally, it is found that the fire resistance performance of square hole fire arrester is no different from that of corrugated fire arrester, compared with the performance of flat plate type and corrugated type fire arrester, and the three dimensional flow field analysis of the finally designed square hole fire arrester is compared with that of flat plate type and corrugated type fire arrester. The circulation performance of corrugated firearm is better than that of corrugated firearm. The lattice orifice arrester designed in this paper refers to the structure of SCR catalytic converter carrier, which means that the catalyst carrier can also have flameproof ability after proper adjustment. It is possible to realize the integration of catalytic converters and fire arresters so as to simplify the composition of the exhaust system of explosion-proof diesel engines, reduce the exhaust resistance, and achieve the purpose of improving the performance of explosion-proof diesel engines. This is of theoretical and engineering significance to explosion proof technology and exhaust gas purification of explosion-proof diesel engine.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK423

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