COMDES-MELT: A Turbofan Engine Icing Risk Analysis Tool(LEW-20027-1)

The engine icing risk prediction code, COMDES-MELT, is a mean-line compressor analysis code coupled with an ice crystal thermodynamic state code. The COMDES-MELT code computes the velocity, pressure, temperature, and flow angles at the leading edge and trailing edge of each blade row, at the hub, mean, and tip sections. This compressor code includes the ability to calculate the effects of water vapor on the fluid properties of the air water vapor mixture based on the mole fraction of air to water vapor. The relative humidity at the engine inlet is specified, and the local specific humidity (mass of water/mass of air) is computed through each component of the inlet-fan-LPC, taking the sublimation, melting, and evaporation of an ice particle into consideration, as well as the local air temperature. The resulting effect of the humid air on the performance of the compressor is computed. Several key parameters have been identified as early indicators of ice accretion: the local wet-bulb temperature, the melt ratio within each blade row, and the ice water flow rate to air flow rate ratio. The local wet-bulb temperature is calculated at each blade row. The geometry section of the code is defined by simple circular arc rotors and stators including stage axial gaps. As the ice particles passes though the compression rotors, stators, and gaps the ice particle melting and evaporation model computes the local melt ratio, change in enthalpy, and particle temperature and diameter through each compressor component. The ratio of ice water flow rate to the air flow rate is computed at the inlet based on the ice water content in the atmosphere and the mass flow rate of air entering the engine. If the limiting values of these key parameters are met, there is a risk that ice will accrete on the surfaces of the compressor. With these parameters as the precursors to ice accretion, the blade row within the compression system can be identified that is likely to experience ice buildup at a particular engine operating condition in the vehicle flight trajectory.