圆排波瓣弯曲混合管引射实验与数值模拟

将圆排波瓣喷管配以不同的弯曲混合管组成引射混合器 ,实验研究了弯曲混合管的几何参数 ,试验结果表明 :当弯曲角β=40°时 ,弯曲混合管的引射流量比φ与同样直径的圆柱混合管相当 ;当β>40°时 ,弯曲混合管的引射流量比φ相比于同样直径的圆柱混合管有较大的下降 ,φ随β的增加下降很快 ;φ随混合管截面比λ的增加先增大后下降 ,虽然峰值小于圆柱混合管的最大引射流量比 ,但是峰值对应的值却近似等同于圆柱混合管的截面比 ;φ随次流进口截面比 σ的增加而接近线性增大。进行了 1 /2的 1 2波瓣喷管弯曲混合管引射混合器的 3 D不可压流流场的数值模拟 ,模拟结果表明 :当 β>40°时 ,弯曲混合管引射流量比 φ下降的主要原因是弯曲混合管转弯部分由于主流射流冲击 ,静压力较高 ,从而弯曲部分附近的有效流通截面积减小 ,严重影响了次流的出流。另外 ,计算的壁面静压系数与测量值符合良好 

Experimental and Numerical Study of Ejection Characteristics of Circular Lobe Ejector with Bend Mixers

For the purpose of infrared stealth, the lobe and bend exhaust nozzle is required for the turbo shaft engine to eject surrounding cooling air and to change the direction of exhaust jets.The test model used was a set of circular twelve-lobe nozzles with bend mixers.The effects of the mixer bend angles β,the mixer to lobe cross sectional area ratio λ and the cross sectional area ratio σ of the secondary inlet to lobe on ejection ratio φ was studied.The experimental results show that for β=40°,the ejection ratio φ of the bend mixer is the same as that of the cylindrical mixer with the same diameter.For β>40°,the ejection ratioφ relative to the cylindrical mixer decreases significantly.With the increase of the mixer cross sectional area ratio λ,at first the ejection ratio φ increases and then decreases.The maximum ejection ratio φ_maxis less than that of the cylindrical mixer,but the optimal cross sectional area ratio λ_maxis about the same as that of the cylindrical mixer.The ejection ratio φ increases approximately linearly with the cross sectional area ratio σ.Because of the symmetrical feature of the lobe mixer,for simplicity,3D incompressible flow field of half of the mixer was numerically simulated.The calculated wall static pressure coefficients agree well with the measured ones.The numerical results show that the main reason for the significant decrease of the ejection ratio φ when the mixer bend angle is larger than 40° is due to the high static pressure along the bend part of the mixer,and the high static pressure chokes the effective flow passage area.