Experimental and numerical investigations on jet impingement heat transfer with different nozzles and enhanced surfaces

Hot air anti-icing systems are essential in aviation engines, preventing ice formation on inlet components during high-altitude flights. A critical factor in enhancing these systems' effectiveness is the application of jet impingement technology. In order to further enhance the performance of jet impingement heat transfer in this application scenario, the research assesses the impact of nozzle type and surface protrusion type on the anti-icing system's performance by integrating experimental and numerical approaches. Findings reveal that circular nozzles outperform swirl and satellite nozzles in heat transfer efficiency in the application of aviation anti-icing system with high jet Reynolds number. The average Nusselt number, indicative of heat transfer rate, can be increased by up to 10.54 % with protrusions. For surface protrusions, sequentially-arranged cylinder protrusions are more effective at Reynolds numbers between 8000 and 48000. Cross-arranged circular truncated cone protrusions do better at higher Reynolds numbers, from 48000 to 80000 which is the range relevant to the hot air anti-icing system. Comparing concave and flat plates with the same type of protrusions, the former shows superior heat transfer performance. The study also establishes correlations for convective heat transfer coefficients and attenuation coefficients on the concave plate with sequentially-arranged cylinder protrusions. By applying the cross-arranged circular truncated cone protrusions, which proved to be the best in our experiments, to the engine nacelle's anti-icing section, the numerical results indicate a 6.21 % increase in anti-icing thermal efficiency and an 8.31 % decrease in air bleed capacity, all under the same heat transfer conditions. The use of protrusion structures in the anti-icing system of an engine nacelle boosts thermal efficiency, lowers air bleed capacity, and reduces the fuel penalty, thereby optimizing overall performance.