弯曲混合管引射系统引射-混合特性数值研究

Numerical Computation for Pumping and Mixing Performance on Mixer-Ejector with Curved Mixing Duct

通过三维CFD数值计算,揭示弯曲混合管-波瓣喷管构成的引射混合系统内流场特性,分析了引射系统主要结构参数对引射混合器性能产生的影响。计算结果表明:混合管的弯曲,迫使主流发生偏转,高速主流对壁面冲击,造成近壁面以及混合管内的静压升高,故降低了系统引射流量;高温核心主流随着弯曲引起的二次流向弯管外侧运动,继而向两侧运动,温度等值线最终呈马鞍状。混合管弯曲角度对引射系数影响很大,弯曲角度的增加造成引射流量的迅速减小。弯曲角度大于40°后,混合管出口的热混合效率急剧降低。波瓣瓣宽增加引起混合管截面比减小和主流速度减小,导致引射流量比的急剧减小。随着波瓣扩张角的增大,引射流量比呈先增加后减小趋势。

Based on three-dimen.sional CFD（Computational fluid dynamics） for the lobed mixer-ejector combined with curved mixing duct, internal flow characteristics of the mixer-ejector are discussed, and effects of the main geometry parameters on the lobed mixer-ejector performance are revealed. Results show that the impingement of the primary flow on the curved wall cause the increase of the static pres- sure near the wall and the interior of mixing duct, and the pumping ratio is reduced. The curved angle of the mixing duct is the most significant factor on the pumping ratio. The pumping ratio is rapidly reduced with the increase of the curved angle. And the thermal mixing efficiency is also sharply reduced when the angle exceeds 40^o. As the lobe width is increased, the pumping ratio is sharply decreased by the reduced area ratio of the mixing duct and primary flow velocity. The pumping ratio is enhanced firstly and then decreased with the increase of the lobe penetration angle.