Effect of Ice and Blade Interaction Models on Compressor Stability Available to Purchase

Incidents of partial or total thrust loss at cruise due to engine icing (mainly ice crystals and super-cooled water droplets at altitudes greater than 10,000 feet) have been recorded over the past several years. As air traffic continues to increase in subtropical areas where high moisture laden air is present at subfreezing conditions, engine icing probability increases. There is a need to better understand compressor dynamics under icing conditions which will help designers to develop more accurate and fast ice detection systems and anti-icing mechanisms. Stage re-matching occurs due to heat exchange between air and ice which dictates the stall inception stage in the compressor. It has been shown that compressor stages re-match under icing conditions — front stages are choked while rear stages throttle due to ice melting and evaporation. Such an analysis uses various empirical models to represent ice-breakup and water-splash processes as ice/water particles interact with rotors/stators. The following paper presents a compressor stall sensitivity analysis around different splash models. The effect of droplet splash at both rotor and stator blades, blade solidity effect and trailing edge shed effect are modeled. A representative 10 stage high speed compressor section operating near design point (100% Nc) is used for the study. Results show that T3 drop and overall compressor operability is a function of evaporating stages and droplet-blade interaction models influence them. A comprehensive compressor stability envelope has been evaluated for different models. It is observed that droplet-blade interaction behavior influences overall compressor stability and stall-margin predictions can vary by as much as 25% with different models. Therefore, there is a need for better calibration and continual improvement of empirical models to capture compressor inter-stage dynamics and stage re-matching accurately under ice/water ingestion.