Heat transfer characteristics and anti-icing performance of hot-air impingement jets

This study presents a combined test and numerical investigation of heat transfer characteristics and anti-icing performance of a nacelle hot-air anti-icing system, which employs a double-row impinging jet configuration integrated with a piccolo tube. High-resolution Nusselt number distributions on the inner surface of the anti-icing cavity were obtained by using transient thermochromic liquid crystal thermography over a Reynolds number range of 15 000 to 40 000, leading to the establishment of a heat transfer correlation model suitable for engineering applications. Through internal-to-external conjugate heat transfer simulations, the anti-icing temperature distributions under typical nacelle operating conditions were further analyzed. The results demonstrate that increasing the Reynolds number from 15 000 to 40 000 enhances the average Nusselt number at the inner lip surface by a factor of 2.4 and raises the hot-air consumption by approximately 2.7 times, whereas the average anti-icing surface temperature increases by only 28.4 ℃. These findings indicate that merely increasing hot-air mass flow provides limited improvement in anti-icing efficiency and highlight substantial potential for reducing air consumption through structural optimization and heat transfer enhancement. Moreover, variations in the angle of attack significantly influence anti-icing performance, as a 5.6° angle of attack reduces the average surface temperature by approximate 13.6 ℃ compared to the 0° condition, underscoring the importance of optimizing jet arrangement to align with regions experiencing the highest icing loads.