Thermal performance comparison between bias acoustic liner and acoustic liner for aircraft anti-icing

Abstract

Acoustic liner is essential to reduce noise pollution in the aircraft engine. There is a suggestion to reduce more noise by installing the acoustic liner on the nacelle lip-skin. However, there are thermal issues including a low temperature of the acoustic liner surface and its poor heat transfer mechanism increase of ice thickness on the nacelle surface. This phenomenon leads to the higher engine power to increase the acoustic liner surface tempera-ture. Thus, aircraft manufacturers proposed to install the bias acoustic liner instead of the acoustic liner on the nacelle lip-skin integrated with an anti-icing system to improve the thermal characteristics of the acoustic liner. Therefore, the present work studies the thermal performance comparison between bias acoustic liner and acoustic liner on the nacelle lip-skin integrated with an aircraft anti-icing system. The simulation study is conducted using the CFD ANSYS Fluent in four different real flight conditions including taxi, climb, hold, and descent. The numbers of both acoustic liners and bias acoustic liners are varied from 1 to 6. The results show that the local dimensionless temperature of nacelle lip-skin with the bias acoustic liner at wrap locations is between 39 % and 100 % higher than that of the nacelle lip-skin with the acoustic liner alone. Further, the average dimensionless temperature of the nacelle lip-skin called the ratio between the average temperature of the nacelle lip skin with respect to ambient and the temperature of the hot air with respect to ambient are analyzed. The maximum average dimensionless temperature of nacelle lip-skin increases to 31.36 %, 26.35 %, 30.43 %, and 13.8 % for the climb, descent, hold, and taxi conditions, respectively, when considering bias acoustic liner instead of acoustic liner. The hold condition shows the highest average Nusselt number with the increasing number of bias acoustic liners, followed by descent, taxi, and climb conditions. In conclusion, the bias acoustic liner enhances the thermal performance of the nacelle lip-skin anti-icing system.