Russian scientists have discovered how volcanic ash affects the performance of aircraft engines.

There are over 1,000 active volcanoes on Earth. Volcanic ash clouds released into the atmosphere pose a significant threat to aircraft. The ash affects the fuselage and aerodynamic surfaces of the airplane, as well as the turbojet engines. The accumulation of ash particles on the nozzle can lead to engine failure. With the global increase in air travel, flight safety has become a top priority, particularly regarding the assessment of engine performance when aircraft encounter volcanic ash clouds. Scientists from ODK-Aviadvigatel and Perm Polytechnic have, for the first time, quantitatively evaluated the volumes of high-temperature zones within the engine tract where ash particles transition into a liquid phase, posing a hazard.

2025-01-04 10:00:14https://naked-science.ru/article/column/pepel-vliyaet-na-rabotu

The research findings have been published in the scientific journal "Thermophysics and Aeromechanics" of the Siberian Branch of the Russian Academy of Sciences.

The accumulation of glassy ash deposits on the nozzle apparatus significantly reduces the cross-sectional area, resulting in persistent compressor surging. Ultimately, this leads to engine shutdown during flight, as occurred on December 15, 1989, when a Boeing 747 entered a dense ash cloud from the Redoubt volcano (Alaska, USA) at an altitude of 7,500 meters. The crew attempted to climb above the volcanic ash cloud at nominal power. As a result, all four engines shut down, and only the pilot's skill prevented a disaster.

“When flying in conditions of ash-laden air, ash particles enter the engine's air intake and then through the compressor into the combustion chamber, where they melt under the influence of high gas temperatures (over 1400 °C). When these particles land on the turbine's nozzle blades, they cool and crystallize, forming deposits. This reduces the space between the blades. Consequently, it leads to a loss of gas-dynamic stability in the compressor and engine shutdown,” explains Taras Abramchuk, deputy head of the combustion chambers department at "ODK-Aviadvigatel".

Researchers from Perm conducted numerical modeling of thermophysical processes in the combustion chamber under three operating modes of the advanced engine: cruising, nominal, and low power mode while exposed to ash from the Shiveluch volcano in the Kamchatka range.

“We found that the volume of high-temperature zones within the combustion chamber for the PD-14 engine, where melting of volcanic ash particles is possible, exceeds 54 percent at cruising mode, more than 81 percent during climb mode, and no more than 25.3 percent at low power flight mode. This confirms the necessity of reducing the engine's operating mode,” comments Diana Popova, an engineer at ODK-Aviadvigatel and a postgraduate student at the "Aviation Engines" department of Perm Polytechnic University.

“The results obtained fully support the recommendations of the International Civil Aviation Organization (ICAO) to reduce engine thrust to low power to decrease the volume of zones where particle melting may occur. Subsequently, exit the ash cloud by turning the aircraft 180 degrees. Returning to nominal mode to fly over the cloud is unacceptable,” adds Alexey Sazhenkov, assistant managing director at ODK-Aviadvigatel and a candidate of technical sciences.

The research conducted by ODK-Aviadvigatel and Perm Polytechnic University has helped assess the melting zones of volcanic ash particles and identify the modes during which there is a risk of engine shutdown. This will enhance flight safety.