基于流场数值模拟的射流清管器喷嘴优化设计

天然气管道中的黑粉严重影响管输效率与安全,现有的带皮碗、磁铁及钢刷的清管器对黑粉的清除效率较低,且易出现卡球现象。射流作用产生的冲击流场对管内积液、杂质的清除效果较好,基于射流原理提出了利用射流清管器清理天然气管道黑粉的方法。为了达到最佳的射流清除效果,需要优化清管器喷射组件中文氏管喷嘴的关键结构参数。文氏管喷嘴结构包括收缩段、水平段及扩散段,其中扩散段的参数对射流效果起关键作用。基于计算流体力学的原理,以Fluent软件为模拟工具,选定实际气体状态模型定义管道内天然气参数,考虑文氏管喷嘴扩散段中扩散长度与扩散角的影响,对清管器的射流过程进行仿真分析。通过比较不同扩散段参数模型在射流流场中流速和湍流动能的云图以及变化曲线,得到具有最佳射流效果的天然气管道射流清管器喷嘴结构。

Optimal design of jet pig nozzle based on numerical simulation of flow field

Pipeline transportation efficiency and safety are seriously affected by black powder in natural gas pipelines. The black powder removal is less efficient, and the pig blockage phenomenon is easy to occur when using existing pig with leather bowl, magnet and steel brush. The impingement flow field generated by the jet can bring a good removal effect against the liquid accumulation and impurities in the pipeline. Based on the jet principle, a method of cleaning black powder in natural gas pipeline by jet pig was proposed. To obtain the most optimal jet cleaning effect, it is necessary to optimize the key structural parameters of the Venturi nozzle in pig nozzle structure. The Venturi nozzle structure comprises a contraction section, a horizontal section and a diffusion section, wherein the parameters of the diffusion section is crucial to the jet effect. Based on the principle of computational fluid dynamics and the simulation tool Fluent, the actual gas state model was used to define the natural gas parameters in the pipeline. Taking into account the influence of diffusion length and diffusion angle in the diffusion section of Venturi nozzle, the jet process of the pig was simulated and analyzed. By comparing the nephogram and variation curves of the flow rate and turbulence kinetic energy of different diffusion section parameter models in jet flow field, the nozzle structure of gas pipeline jet pig with the optimal jet effect was obtained.