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Erosion Resistant Coatings for Large-Diameter Gas Turbine Engine Compressor Integrally-Bladed Rotors (IBRs) and Lift-Fan Blades

Description:

TECHNOLOGY AREA(S): Air Platform 

OBJECTIVE: Develop and apply erosion-resistant coatings to lift fan blades and/or large-diameter IBRs (integrally bladed rotors) for large Short Take-off and Vertical Landing (STOVL) aircraft.  

DESCRIPTION: Aircraft operating in sand/dust environments experience erosion of the gas turbine engine compressor airfoils that deteriorates engine performance; increases fuel consumption; increases maintenance, logistic support, and costs; and decreases safety-of-flight. This will present a particular challenge for large STOVL aircraft, which are likely to ingest large amounts of abrasive particles during the critical take-off and landing stages of operation. While the implementation of inlet barrier filters has provided some protection for helicopter engine compressor airfoils, that solution will not help here because the lift fan blades in a STOVL aircraft are directly exposed to the full force of any dust or debris that may be kicked up from the ground during lift-off and landing. The successful application of erosion-resistant coatings designed to handle those particular conditions will be key to sustaining safety of flight and aircraft system performance. Historically, the application of erosion-resistant coatings in the compressor section of helicopter engines operating in desert environments has resulted in increased engine time-on-wing and engine performance retention. However, the compressor airfoils in helicopter engines are much smaller (typically 10 cm or less in length) than the compressor airfoils on some large STOVL aircraft engines’ IBRs. For example, a first-stage IBR can measure approximately one-meter in diameter. These large-size IBRs are expensive to manufacture and replace. Hence, the potential of an erosion-resistant coating maintaining component efficiency and delaying component degradation of large-diameter IBRs will be critical in reducing total operating costs. A previous SBIR topic (N08-144) focused on developing an erosion-resistant coating with damping properties for the compressor airfoils on the JSF aircraft’s integrally bladed rotors (IBR), but that effort ended well short of implementation. This project seeks erosion-resistant coatings for the much more vulnerable lift fan blades and main engine IBRs on a production basis. The coatings must be able to withstand the austere operating environments of gas turbine engines such as high cycle fatigue (HCF) and stresses due to surge and aerodynamic and centrifugal loads. At the same time, they should not spall or delaminate after absorbing foreign object damage. 

PHASE I: Determine the feasibility of applying erosion-resistant coatings on large-diameter engine fan/compressor IBRs and lift fan blades. 

PHASE II: Demonstrate the application of the coating on a large-diameter IBR and/or lift fan blade. Conduct erosion tests on current bill-of-material and coated large-diameter IBRs and/or lift fan blades to characterize the baseline erosion rates. Develop a plan for productionizing the coating process for large-diameter IBRs and/or lift fan blades, including estimates for non-recurring and recurring costs to apply production coatings, and predict savings and benefits for large STOVL aircraft engines. 

PHASE III: Transition application of the selected erosion-resistant coatings to the JSF engine compressors and/or lift fan IBRs. The application of erosion-resistant coatings on large diameter compressor airfoils and IBRs has potential application for compressor airfoils on large turbofan engines powering commercial aircraft fleets. 

REFERENCES: 

1. Valleti, Krishna, Puneet, C., Rama Krishna, L., and Shrikant V Joshi, “Studies on cathodic arc PVD grown TiCrN based erosion resistant thin films,” Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. Vol. 34 (4), Article number 041512. July 1, 2016. ; 2. Urbahs, A., Rudzitis, J., Savkovs, K., Urbaha, M., Boiko, I., Leitans, A., and Lungevics, J., "Titanium compound erosion-resistant nano-coatings", Key Engineering Materials, Vol 674 (2016) PP 283-8.; 3. SBIR topic N08-144 (Erosion Resistant Coatings for Large Size Gas Turbine Engine Compressor Airfoils); solitation number 2008.2

KEYWORDS: Erosion; Resistant; Coatings; Airfoils; Lift Fan Blades; Gas Turbine Engines 

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