Flow and thermal performance analysis of an oscillating jet nozzle in a flat double-wall optimized via the response surface method

• The cooling performance of a single-nozzle oscillating jet was investigated using Response Surface Methodology (RSM). • Using Response Surface Methodology (RSM)to optimize the geometric parameters of the oscillating jet nozzle. • Geometric factors on the cooling performance are optimized. • The application of oscillating jet in the double-layer wall of a flat plate. To enhance the heat transfer uniformity of double-wall cooling, this study proposes a novel structure integrating self-excited oscillating jet nozzles with double-wall cooling. The cooling performance of a single oscillating jet nozzle was first investigated using the Response Surface Methodology (RSM). By predicting the average Nusselt number on the impingement target surface and the maximum jet deflection angle, the geometric dimensions were optimized, and the optimized configuration was applied to a flat-plate double-wall system. Under identical operating conditions, the thermal performance of three configurations—Inline Impingement Jet (IIJ), Inline Oscillating Jet (IOJ), and Staggered Oscillating Jet (SOJ)—was experimentally compared. Numerical simulations analyzed the flow and heat transfer characteristics at different Reynolds numbers. Results show that under experimental conditions, the average target surface temperature of IOJ is lower than that of IIJ, while the heat transfer capacity of SOJ is significantly enhanced compared to IOJ. At Re = 70,000, compared to IIJ, IOJ and SOJ improved heat transfer by 10.8 % and 36.7 %, respectively. However, the oscillating jet configurations exhibit higher flow resistance coefficients. Although the staggered arrangement (SOJ) significantly reduces the resistance coefficient compared to the in-line arrangement (IOJ), its overall comprehensive cooling effectiveness remains relatively low. The oscillating jet device notably improves heat transfer uniformity: as the Reynolds number increases, the temperature non-uniformity factor decreases for all models. At Re = 140,000, the TR values for IIJ, IOJ, and SOJ are 0.082, 0.074, and 0.068, respectively, indicating that the SOJ configuration achieves the best temperature uniformity.