合成射流作用机理及其对共轴射流掺混的影响

对合成射流流场及其作用下的内、外涵共轴射流流场进行了二维非定常数值模拟, 研究了合成射流流场和共轴射流流场情况.结果表明,合成射流由一系列对称分布在中心线 2侧的旋涡对组成,频率与激振频率相同,对外场构成一扰动力;涡对自形成后向远处运移 速基本稳定;腔内和腔外涡对的形成及发展变化过程总体保持一致,在每时刻则呈现截然相 反的发展态势;中心线速度的降幅起伏变化分布是由激励器的激振变化引起的,体现了涡量 产生、发展变化的基本特征;合成射流激励器的采用可使共轴射流截面掺混率比未加激励时 得到增加,增强了共轴射流的掺混效果.

Process mechanism of synthetic jet and its effect on the mixing in coaxial jets

Two-dimensional unsteady numerical simulation was carried out to inve s tigate the flowfields surrouding a synthetic jet actuator and its effect on the mixing in coaxial jets. The synthetic jet flowfield and the coaxial jets flowfie ld were investigated. The results show synthetic jet comprises a series of vorte x pairs, which distribute around the centerline symmetrically. Its frequency kee p same to the actuator′s frequency. This is a disturbed force for the outer flo w field. The movement velocity of vortex pairs is nearly constant. The formation a nd development of the outer flowfield have the same rule as that of the inner fl owfield. But they are opposite to each other at the certain moment. As a result of actuating device, the centerline velocity distribution shows that the amplitu de decreases gradually, which represents the radical characteristic of vorticity d evelopment. The mixing ratio of coaxial jets increases comparatively because of the synthetic jet actuators, and the mixing effects in coaxial jets also become more agreeable.