The combination of a microchannel and a circular synthetic jet has been proven as a promising cooling technology for microelectronic devices. However, the flow control and heat transfer characteristics of a circular synthetic jet in a microchannel are still not clear. This work numerically investigates the interaction between a circular synthetic jet and a cross flow in a microchannel using an in-house solver based on the finite volume method and analyzes its impact on the heat transfer process to further understand the heat transfer enhancement induced by a circular synthetic jet in a microchannel. The effects of the synthetic jet Reynolds number (Re_sj = 0 to 324), dimensionless stroke length (L/H = 1.8432 to 92.16), and cross-flow Reynolds number (Re_c = 188 to 470) are studied herein. The results show that the main body of the vortex structure generated by the circular impinging synthetic jet during the discharge stage is a hairpin vortex. During the downstream motion of the hairpin vortex, the vortex legs gradually stretch and evolve into a pair of large-scale longitudinal vortex. The heat transfer enhancement induced by a circular synthetic jet can be divided into two parts according to the difference in acting mechanism: an impinging region with severe heat transfer fluctuation and an entraining region with a relatively stable heat transfer performance. The parametric study demonstrates that the enhancements of the time-area-averaged Nusselt number and the total pressure drop are mainly affected by Re_sj, while the transient heat transfer performance is determined by L/H. Furthermore, the growth rates of the time-area-averaged Nusselt number and the total pressure drop are almost independent of Re_c.

微通道和圆形合成射流的结合已被证明是一种有前途的微电子设备冷却技术。然而，在微通道中圆形合成射流的流量控制和传热特性仍然不清楚。这项工作基于有限体积法，使用内部求解器，以数值方式研究了圆形合成射流与微通道中的横流之间的相互作用，并分析了其对传热过程的影响，从而进一步了解了由圆形引起的传热增强微通道中的合成射流。合成射流雷诺数（Re _sj  = 0至324），无量纲行程长度（L / H = 1.8432至92.16）和错流雷诺数（Re _c （188-470）。结果表明，在放电阶段，圆形撞击合成射流产生的旋涡结构的主体为发夹式旋涡。在发夹涡旋的下游运动期间，涡旋腿逐渐伸展并演变为一对大型纵向涡旋。根据作用机理的不同，圆形合成射流引起的传热增强可分为两部分：传热波动大的冲击区域和传热性能相对稳定的夹带区域。参数研究表明，时域平均努塞尔数和总压降的增加主要受Re _sj影响。瞬态传热性能由L / H决定。此外，时区平均努塞尔数的增长率和总压降几乎与Re _c无关。