Numerical Simulation And Design Of Airplane’s Hot-air Anti-icing System

It becomes extremely important to study the effects of icing phenomenon on aerodynamic characteristics and design the corresponding anti-icing system,because the airplanes’ icing phenomenon seriously affects aero:dynamic performance and flight safety during the flight.This paper adopts numerical simulation method to study the effects of several icing parameters on the aerodynamic characteristics of airplanes and designs corresponding hot-gas anti-icing system aimed at critical state point.The main work includes the following aspects:First,we analyzed the influence law of the airfoil’s aerodynamic characteristics affected by the changes of icing parameters,such as icing temperature,flight velocity,ambient pressure,water droplet diameter and liquid water content.Then according to the icing atmospheric conditions of transport category airplanes in appendix C of CCAR25 Department,a series of typical icing state points are determined for a certain airfoil.And the icing calculation of each state point is carried out to obtain the ice shape of each state point.Division and reconstruction of the airfoil grids before and after icing are both done.Calculation of aerodynamic characteristics before and after icing is obtained as well.Second,for the purpose of design the hot air anti-icing system,we focus on the study of structure parameters of piccolo,and summarize theoretical design process.The calculation method of pressure drop and temperature drop is given in this paper,and the above calculation method is about diametric arrangement holes section and variable diametric non-arrangement holes section of piccolo.According to the design process of piccolo and calculation method,a procedure is designed to calculate the parameters of piccolo.Third,a method aimed at calculating thermal coupling in inner and outer flow field is proposed based on user-defined functional features of Fluent.According to the calculation results of outer flow field,droplet impingement characteristics are obtained by Euler method.Based on the calculation results of droplet impingement characteristics,we adopt surface anti-icing thermal load calculation method which is based on Messinger model to calculate each heat flow in the outer surface of the skin.Thus,the heat absorbed by each control volume on the outer surface of the skin can be determined.In the end,the interpolation method where the distance between the two control units is nearest is adopted to realize heat flow density interpolation of inconsistent interface in inner and outer flow field.So we achieve the thermal coupling in inner and outer flow field.We calculate the anti-icing system by icing calculation software FENSAP-ICE,and compare that with the numerical simulation results.The feasibility of the proposed numerical simulation method is verified,and the structure of hot-gas anti-icing system is optimized simply.