化学激光器环形与线形分流管道对比的数值分析

Numerical Investigation of Comparing Annular with Linear Distribution Flow Pipeline in Chemical Laser

环柱型化学激光器中使用的分流管道的总管为环形弯曲管道,支管分布在内侧圆弧或外侧圆弧上,结构与线形分流管道有较大差别。应用计算流体力学方法,对上述各分流管道进行了三维的数值模拟及对比分析。结果表明,线形分流管道总管内的总压高于支管分布在外侧圆弧上的环形管道,但低于支管分布在内侧圆弧上的环形管道;无论是支管分流,抑或环形管道内的二次流现象都会使总管截面上产生径向速度,使得流体流动呈现明显的三维特征;分流管道各支管流量沿主流流动方向基本上是上升的,这与总管的总压分布趋势相反,而与总管的静压分布趋势相似;比较而言,支管分布在外侧圆弧上的环形分流管道的支管流量波动幅度最小,在均匀分配气流方面最具优势,线形分流管道居中,支管分布在内侧圆弧上的环形分流管道最差。

Distribution flow pipeline used in cylindrical chemical laser is composed of an annular general pipeline and a limited quantity of branch pipelines that are connected with the inner or outer circular arc of general pipeline.Its structure and flow field characteristics differ from those of linear distribution flow pipeline used in conventional chemical laser.Flow field characteristics of above-mentioned three kinds of distribution flow pipelines were analyzed contrastively based on three-dimension computational fluid dynamics methods.The numerical simulation results demonstrate that total pressure of general pipeline in linear distribution flow pipeline is higher than that in outer-circular-arc annular pipeline,but lower than that in inner-circular-arc annular pipeline.Both distribution flows of branch pipelines and secondary flows produced in annular general pipeline can excite radial velocity on the section plane of general pipeline.These phenomena enable the gas flow of general pipeline to have remarkable three-dimension characteristics.Mass flow rates of branch pipeline outlets are higher and higher along the direction of main gas flow movement.Its trend is contrary to upward tendency of total pressure in general pipeline,but is similar to downward tendency of static pressure in general pipeline.By comparison,Mass flow rate fluctuating amplitude of branch pipeline outlets in outer-circular-arc annular distribution flow pipeline is smaller than that in linear distribution flow pipeline,and the amplitude in inner-circular-arc annular distribution flow pipeline is the biggest of the three.As a result,outer-circular-arc annular distribution flow pipeline is of advantage among the three methods in distributing uniformly gas flow,while inner-circular-arc annular pipeline is the lowest and the linear distribution flow pipeline goes between the other two.