Model for generation the liquid phase zones for volcanic ash melt in the combustion chamber of a turbojet: different flight modes for a mainline aircraft

The study presents the numerical simulation results for a process of the ash liquid phase zone generation in the aircraft engine combustion chamber. The simulation was performed for three operation modes: the aircraft enters an ash cloud while cruise flight, the aircraft exits the ash cloud during climb-out; the aircraft exits the cloud during the flight idle mode (recommended by ICAO). This study was conducted for the case of a dual-flow turbojet engine PD-14 (the mainline aircraft MS-21) under the impact from the Sheveluch volcanic ash in the air. Our simulations revealed that there are significant zones inside the PD-14 engine combustion chamber where the gas temperatures are above the meting point for volcanic ash. The high temperatures zones (creating a risk of volcanic ash melting inside the engine) account for over 54 % of the flame tube volume. Additionally, for the nominal flight mode (climb-out), the volume of ash melt zone exceeds 81 % of the total volume, and the flight idle mode provides only 25.3 % of the volume.