A comparative study of passive control on flow structure evolution and convective heat transfer enhancement for impinging jet

作者：Du, Xuzhi; Yang, Zhigang^*; Jin, Zheyan; Xia, Chao; Bao, Di

来源：International Journal of Heat and Mass Transfer, 2018, 126: 256-280.

DOI：10.1016/j.ijheatmasstransfer.2018.01.061

• Impinging jet
• Passive control
• Flow structure
• Heat transfer
• PIV
• IR thermography
• LES

The present study experimentally and numerically investigated the passive control on flow structure evolution and convective heat transfer enhancement for impinging jet. Four different impinging jets, including a baseline circular jet (CJ) and three passive controlled jets, i.e., an elliptic jet (EJ), a circular-chevron jet (CCJ) and an elliptic-chevron jet (ECJ), were comparatively analyzed by utilizing the Particle Image Velocimetry (PIV) technique, infrared (IR) thermography and large eddy simulation (LES) over a wide range of jet-to-wall distances (H/D) at the jet Reynolds number (Re) of 20,000. The results showed that, unlike CJ which presented a general shedding of axisymmetric toroidal vortices, EJ showed highly deformed toroidal structures accompanied with the axis switching effect, both CCJ and ECJ exhibited the well-organized counterrotating streamwise vortex pairs developing from the chevron notches. All the three passive controlled strategies were found to induce a stronger mixing and fluctuating activity near around the stagnation region, especially for ECJ (i.e., the passive-passive controlled device) which showed the highest turbulence level approaching the target wall due to the double-passive enhancement. Moreover, compared with the baseline jet CJ, all the passive controlled jets achieved a significant heat transfer improvement in the vicinity of the stagnation point, particularly for ECJ which presented the highest heat transfer enhancement of about 41% at H/D = 5. Whereas both CCJ and ECJ were found to exhibit a less-than-ideal heat transfer performance at a small H when the heat transfer uniformity was specifically considered, due to the anisotropic thermal imprint distributions.

• 出版日期2018-11
• 单位中国商用飞机有限责任公司北京民用飞机技术研究中心; 同济大学