There are numerous conditions where gas turbine engines ingest small particulates. Of particular concern are the particles (~1-10 micrometer) that are ejected into the atmosphere as volcanic ash. Ingestion of these particles has numerous detrimental effects. Particle collisions cause abrasion of compressor blades, leading to loss of efficiency. Ingested particles that partially or completely melt in the combustion region can deposit on downstream structures, leading to decreased airflow. These particles usually cannot be removed and may require replacement of the engine. Such particles also plug the small holes used for film cooling of turbine blades and nozzle guide vanes, leading to blade overheat and failure. The proposed research will develop a discrete-element method for the transport, reaction, collision and adhesion of small particles in a gas turbine engine. This model will be developed to be incorporated with existing CFD codes. This tool will allow engine designers to assess the vulnerability of their designs to ingested particles and to examine the efficacy of proposed mitigation strategies. Since both military and commercial aircraft are subject to performance degradation due to ingested particles we anticipate interest from military, commercial and industrial gas turbine designers and manufacturers.
Benefit: Development of technologies for mitigation of the effects of ingested reactive particles by gas turbines engines is of interest to DoD for application to all aircraft, including fixed wing craft and rotorcraft. In addition, this technology may be of interest to new ship and land vehicle designs powered by gas turbines to preempt the potential use of reactive particle clouds to degrade the performance of their power plants. The development of such mitigation technologies will be of high level interest to owners and operators of commercial aircraft and commercial power plants that employ gas turbines. Commercial aircraft are interested in order to minimize the degradation of performance and the possibility of disaster that could occur due to the aircraft encountering an unseen cloud of reactive particles, such as that due to a volcanic eruption. Commercial power plants should want to harden their gas turbines against potential terrorist attacks by the release of clouds of reactive particles to degrade the performance of the plants and yield blackouts. There are (outside of formerly Iron Curtain countries) about a dozen aircraft (airplane, helicopter, missile) GT jet engine manufacturers, as well as land-, ship- or vehicle-based GT manufacturers. We expect that each would have about a dozen numerical codes that could use the particle model in several groups sprinkled over the company. Also there are roughly a dozen research groups (e.g., university departments, institutes) in the US and a like number in Europe, each with several codes. Further, with appropriate modifications to our particle reaction model, the numerical tool we propose will be applicable to a broad range of activities: transport of evaporating droplets in medical aerosols, distribution of spores within buildings, adherence of radioactive particles in nuclear accident sites, accretion of salt particles in marine equipment and ice particles on aircraft. Importantly, our work in Phase II as outlined above will cast our numerical tool in the form of a User Defined Function for the commercial fluid dynamics computer code Fluent, which is perhaps the most widely used such code. This will make the implementation of our tool effectively automatic (and thus attractive) for this wide community of users. With these considerations, we expect that with the successful demonstrations in Phase II with Pratt & Whitney, we will have a market for 10 20 tools in 2021, with that number increasing each year so that by 2025 we will sell about 50 tools to Fluent users and others. Consulting, where we provide advice or perform simulations for customers, will be an active part of our commercial venture. We expect that at least three such contracts per year is realistic.
Keywords: particle collision, particle collision, reactive particles, Gas Turbines, particulate flow, Volcanic ash, Computational Fluid Dynamics, particulate fouling, discrete element method
