COMBUSTION RESEARCH & FLOW TECHNOLOGY INC — Department of Defense STTR Phase I: N23A-T003

Description

Ingestion of silicate particles into aircraft gas turbine (GT) engines remains a serious hazard to both commercial and military aircraft. Helicopters and low-flying fixed-wing aircraft in desert environments are exposed to airborne sand particulate. Both commercial and military aircraft can be exposed to runway dust as well as high-altitude volcanic ash. These silicate particulates present a hazard to aircraft, particularly if ingested into GT engines where they can block cooling passages and cause structural and performance degradation when deposited on internals either in solid or molten form. It is essential that mitigation strategies be developed to minimize the impact of particulate ingestion on engine integrity. To do this in an efficient and economical way, computational tools are required to allow prediction of particle transport and behavior in engine airflow passages, including high-temperature transition to a molten state and deposition on engine surfaces. CRAFT Tech has developed an advanced simulation methodology for modeling the transport and deposition of solid and molten silicate-based particulate (e.g. sand, ash, road dust) in a Reactive Solids Tool (RST), which has been validated for silicate deposition up to 1600K temperatures. The RST can track millions of particles of varying size and material through a complex geometry, predict local regions susceptible to solid, molten or semi-molten particle deposition, and report the state (solid/molten) and time-dependent deposit temperature and thickness. Unique features of the RST include a default silicate material database, and a state-of-the-art molten particle deposition model calibrated to gas-phase temperatures up to 1700K. The RST is fully functional for parallel-computing with either RANS or LES solvers and can be used for production engineering calculations to predict the potential for solid/molten particle deposits in complex high-temperature flows. Significant deposit buildup on a surface presents additional modeling challenges. First, the presence of deposits must be accounted for by modifying the computational grid to replicate the flow blockage produced by the deposit. A second challenge is properly accounting for the role of surface temperature on deposition. The objective of the proposed effort is to extend the RST to account for the effects of deposit accumulation on flowfield blockage and thermal interaction with the engine structure. CRAFT Tech will partner with the Ohio State University to extend the RST modeling capabilities with mesh-morphing linked to the deposit thickness, coupling of a conjugate heat transfer model accounting for deposit buildup, and extension of the RST deposition model to account for surface temperature and slag deposit properties. These enhancements will provide OEM’s and design/analysis personnel the capability to accurately characterize the effects of deposit buildup on gas turbine performance, maintenance, and structural damage.