Heat transfer enhancement on a concave surface using sweeping impinging jets: Comparison of vortex-based and conventional oscillators

Abstract

While the impinging sweeping jet generated by a conventional fluidic oscillator has been extensively investigated for its remarkable convective heat transfer performance, the cooling performance of the recently designed vortex-based fluidic oscillator on impinged hot plates remains unexplored. This study numerically investigates the cooling performance of oscillatory jets generated by the vortex-based fluidic oscillator compared to the conventional fluidic oscillator and a steady non-oscillatory jet impinging on a hot concave surface. The Fluent 2023R2 software was employed for solving the unsteady Reynolds-averaged Navier–Stokes equations with the k–ω SST model through the finite volume method. Numerical simulations were conducted at various dimensionless nozzle-to-surface distances (X/D = 2, 4, and 6) and Reynolds numbers (20,000, 30,000, and 40,000). The performances of both oscillators were assessed through the time-averaged velocity, temperature, and Nusselt number. The results demonstrated that the vortex-based fluidic oscillator, as an innovative type of fluidic oscillator, outperformed conventional fluidic oscillators by enhancing heat transfer and reducing pressure drop, attributed to its smaller size and higher operational frequency. At X/D values of 2, 4, and 6, the mean Nusselt number for the vortex-based oscillator exhibited respective increases of 19 %, 23 %, and 16 % compared to the conventional oscillator. In addition, these values were respectively 38 %, 34 %, and 24 % higher than those for the steady non-oscillatory jet. Furthermore, the thermal enhancement factor of the vortex-based oscillator demonstrated increases of 20 %, 23 %, and 21 %, respectively, in comparison with the conventional oscillator. These findings suggest that the novel vortex-based fluidic oscillator holds significant promise for replacing conventional oscillators in industrial cooling applications.

Keywords

• Cooling performance
• Concave surface
• Vortex-based oscillator
• Conventional oscillator
• Sweeping impinging jet
• Pressure loss