Cooling performance improvement of impingement hybrid synthetic jets in a confined space with the aid of a fluid diode

• Published in: Applied thermal engineering 2019-07, Vol.157, p.113749, Article 113749
• Main Authors: Yu, Qinghua, Mei, Ziyue, Bai, Mengqi, Xie, Danmei, Ding, Yulong, Li, Yongliang
• Format: Article
• Language: English
• Subjects: Aerodynamics; Air temperature; Computational fluid dynamics; Computer simulation; Confined space; Confined spaces; Cooling; Diodes; Flow characteristics; Fluid diode; Fluid flow; Heat transfer; Impingement; Impingement cooling; Nozzles; Performance enhancement; Synthetic jet; Synthetic jets; Volumetric efficiency
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2019.113749

•Hybrid synthetic jet based on fluid diode is used to suppress hot air recirculation.•Impingement hybrid synthetic jet with a longer convergence nozzle performs better.•The optimal hybrid synthetic jet obtains a high volumetric efficiency up to 95.8%.•The target temperature decreases by 24.9 °C and the Nusselt number increases by 54.7%. For the conventional synthetic jet in a confined space, the recirculation of heated air at a small nozzle-to-surface spacing results in deterioration of its impingement cooling ability. To overcome this drawback, various novel fluid diodes are designed and introduced to form hybrid synthetic jets in this paper. Numerical analyses are carried out to reveal the cooling performance enhancement mechanism of the hybrid synthetic jets with the aid of fluid diodes. Instantaneous images of velocity contour and streamline at one cycle are comparatively presented to elaborate on their flow characteristics. Based on the simulation results, the volumetric efficiency, air temperature at the nozzle exit, average temperature on the heated surface and average Nusselt number are further calculated to quantify the improvements of the proposed hybrid synthetic jets compared to the conventional synthetic jet. The hybrid synthetic jet with a convergence nozzle generates the best cooling ability among various configurations. This study provides significant guidance for the design of novel hybrid synthetic jets with high-efficiency impingement cooling performance.