Rolls-Royce and Pratt & Whitney have signed a joint agreement with Virginia Tech for pre-competitive research focused on the impact of environmental contaminants on aeroengine operation and testing. The four-year project will leverage Virginia Tech’s research and cross-discipline expertise on engine operation, instrumentation, and geosciences as well as the current research relationships that both Pratt & Whitney and Rolls-Royce have with the university.

The multidisciplinary group, teamed with Mechanical Engineering, Aerospace and Ocean Engineering, and Geosciences, will work together to tackle the impact of the airborne particulate on aircraft engines, which is a huge challenge for today’s aviation industry.

—Changmin Son, the Rolls-Royce Commonwealth Professor at Virginia Tech

This research relationship continues longstanding collaboration between Rolls-Royce and Pratt & Whitney on issues that are common across the aerospace industry. The two companies have partnered on several government-based research projects, including a study focused on volcanic ash damage to aircraft engines.

In an open-access paper published in the journal Aerospace in 2021, researchers from the University of Manchester and Rolls-Royce Civil Aerospace outline the problem:

The dangers posed to the safe operation of gas turbine engines in the presence of airborne particulate such as volcanic ash and mineral dusts are well documented, ranging from benign events resulting in minimal damage to engines being rendered inoperative and safety margins compromised. Encounters between aircraft and volcanic ash remain rare, but their consequences are well known due to several high-profile incidents involving commercial airliners.

… Airborne mineral dust is encountered with much higher frequency due to the growth of aviation in arid regions and can be especially severe during dust storms. Due to its constant presence in these environments, dust ingestion is often unavoidable, and although not encountered in large quantities over short time periods typical of volcanic ash, multiple flight cycles combined with dust storms can see the total quantity ingested reach comparable levels. However, to date, analogous safe quantities of mineral dust that can be tolerated by an engine have yet to be established.

This inability to avoid frequent ingestion of airborne particulate combined with the impracticality of airspace closures has precipitated a shift towards model-driven, risk-based approaches in which certain levels of damage, performance loss and reductions in safety margin can be tolerated to maintain efficiency of operations. Key to this is the ability to determine safe quantities of airborne particulate that can be ingested by an engine without compromising safety margins.

—Ellis et al.

Deposited volcanic ash on the high pressure turbine nozzle guide vanes of a Rolls-Royce RB211-524C engine involved in an encounter with the volcanic ash plume from the 1982 eruption of Mount Galunggung in Indonesia. Ellis et al.

Work on this front has taken place in the US, UK, and around the world, with various groups developing some of the basic understanding needed before complex modeling can be undertaken. The collaboration between Pratt & Whitney, Rolls-Royce and Virginia Tech in this research initiative is designed to add the more complicated engine testing available at Virginia Tech to further develop mitigation strategies, and to provide information back to these more basic research activities from actual engine operations.

Rolls-Royce has enjoyed a strong relationship with Virginia Tech for decades, collaborating on a variety of research projects to measure and evaluate engine performance under different conditions. This new joint research project will help further industry understanding of airborne particles—a key contributor to engine degradation—and their impact on operability.

—Lisa Teague, head of Emerging Technologies and Innovation at Rolls-Royce LibertyWorks

Detrimental effects of particle ingestion are common concerns in the aerospace industry and can lead to accelerated engine aging and performance loss.

Pratt & Whitney sees this as a great opportunity to improve our basic understanding of an issue that is critically important to our entire industry. Virginia Tech has the right expertise and facilities to help us make an impact as the joint research team will investigate the fundamentals of particle (sand/dust) properties as the particles pass through the engine with the goal of improving analysis methods to better predict those effects.

—Frank Preli, vice president, Propulsion and Materials Technologies, Pratt & Whitney

The short-term goal for this work is leveraging learning from smaller engine tests, which will be performed on a Rolls-Royce M250 engine, to influence large engine test programs by accounting for the difference in engine architecture and operating conditions.

The impact of environmental contaminants costs hundreds of millions of dollars of losses annually for both commercial and military operations as air travel has expanded around the world. This is a multifaceted problem that ranges from basic scientific questions about complex chemistry of the environmental contaminants within the engine, to fleet operations, maintenance procedures, engine design and even weather prediction. It spans a wide range of scientific issues to practical engineering problems which are well suited to a multi-discipline focused project.

Resources

• Ellis, Matthew, Nicholas Bojdo, Antonio Filippone, and Rory Clarkson. (2021) “Monte Carlo Predictions of Aero-Engine Performance Degradation Due to Particle Ingestion” Aerospace 8, no. 6: 146. doi: 10.3390/aerospace8060146