Indian Journal of Science and Technology

Abstract

Heat distribution characteristics e.g. temperature, the local Nusselt number, local heat flux etc., contribute to ice accretion on all critical surfaces of aircraft. The non-uniformity in heat distribution at these surfaces results in low temperatures and runback ice accretion downstream from these surfaces areas. Most of the previous studies merely extracted local temperature or local Nusselt number profiles at certain locations/cross-sectional planes on the surface to describe the uniformity of the temperature, which of two does not represent the overall temperature distribution on the entire surface. This paper proposes using the Coefficient of temperature deviation (Ctem dev ), which is obtained using Statistical Quality Control (SQC) and statistical methods, as the measurement of the anti-icing system’s temperature uniformity. The discussion covers the uniformity of the temperature distribution in a nacelle lip, which is produced by Swirl Anti-Icing (SAI) system. This paper also numerically investigates the effects of an SAI system's nozzle length and nozzle rotation angle on the temperature uniformity over several Reynolds numbers (Re) in a D-chamber, ranging between 7.5 x 104 and 4.1 x 105 . At Re= 7.58 x 104 and velocity of free stream = 48.75 m/s, Ctem dev decreases by 13.7% as the Nozzle Direction Angle (NRA) changes from 0⁰ to 13⁰, which indicates that changing nozzle direction significantly improves the uniformity of the temperature distribution on a nacelle lip surface. However, according to the numerical results, Ctem dev is insensitive to nozzle length. The results also show that the uniformity of the temperature distribution improves as the Re increases, for NRA values of both 0⁰ and 13⁰.
Keywords: Anti-Icing, CFD, Coefficient of Temperature Deviation, Nusselt Number, Reynolds Number, Temperature Uniformity