高压天然气多孔节流效应及冲蚀特性分析

Multi-Hole Throttling Effect and the Erosion Characteristics of the High Pressure Natural Gas

基于欧拉-拉格朗日多相流模型方法 ,采用RNGk-ε湍流模型和Sutherland viscosity law可压缩流体黏度修正模型及改进的冲蚀模型,对高压天然气单孔和多孔节流过程进行数值模拟。通过高压天然气单孔节流数值模拟质量流率变化规律,与理论计算结果对比,验证了所采用的模型和计算方法的准确性,并考察了高压天然气流经单孔和多孔突缩结构的不同节流效应及冲蚀特性。计算结果表明,天然气流经多孔固定节流油嘴降压后,体积膨胀形成的最高流速值明显低于单孔固定油嘴,同时多孔均匀射流减少了单孔射流形成的卷吸冲蚀损伤,并在多股射流下的搅混作用下,冷核心能迅速混合,在后续油嘴腔体内更易实现压力回升和速度稳定现象,相比单孔节流可以有效地抑制冲蚀损伤及天然气水合物生成几率。

Based on Euler-Lagrange multi-phase flow numerical simulation method,the single hole and multi-hole throttling process of the highly compressed natural gas was studied by using the RNG k-ε turbulent model,the Sutherland Viscosity Law compressible fluid viscosity model,and the advanced erosion model numerical simulation.The calculated mass flow variation law in the throttle choke is compared with the theoretical calculations,which verifies the adopted models and calculating methods.And then the throttling effect and the erosion characteristic of the high pressure natural gas was studied to check its specific law with different throttle holes by using the advanced erosion model.Results show that,high pressure natural gas can reduce pressure and expansion when it flows through the single hole and multi-hole throttle choke,leading to a highspeed jet region near its outlet.But the maximum jet velocity of multi-hole throttle choke is significantly lower than that of the single hole.At the same time the multi-hole uniform jet reduces the vortex entrainment and the wall erosion damage,making it easier to mix the cold core and achieve stable pressure recovery at the role of the multi-jet mixing effect.Therefore,the multi-hole throttling can effectively restrain the erosion damage and the gas hydrate formation probability.