TECHNOLOGY AREA(S): Air Platform, Electronics, Sensors

ACQUISITION PROGRAM: Navy and USMC gas turbine aero-engines (e.g., T700, F414, F135, etc.) and future aero-engine systems

OBJECTIVE: Develop an improved engine-mounted sensor system for detection, classification, and characterization of inlet particles to gas turbine engines.� The sensor and associated processing equipment should be compatible with aircraft size, weight, and power (SWaP).

DESCRIPTION: Coarse sand to fine dusts, aerosol particulates, organic dirt, aerosol and water-spray salts at low altitudes, uniquely volcanic ash generally at high altitudes, and any similar natural minerology from global Naval littoral spaces are currently ingested into Naval propulsion and power gas turbines in large but unknown and variable amounts.� Significant internal accumulations are at times seen in repair processing, occluding both hot-primary and cooler-secondary flowpaths.� A Naval gas turbine may process up to one million pounds of air during each two-hour sortie with instantaneously varying contaminant levels.� As engines are operated to higher gas and component surface temperatures, rapid accumulation of the combined dusts and salt may generate molten fusions in turbine hot sections, especially when low melting temperatures mixtures are ingested.� General examples of low melting temperature mixtures have been coined �Calcia-Magnesia-Alumina-Silicate (CMAS)�.� However, the inlet ingested natural minerals and salts are not so simply defined.� Verified risks to flight operations due to ingested mixture chemistries and kinetics of adhesion and sintering are forming thick deposits of �CMAS�.� These and other large airborne particles can also erode compressors and seals, and different unique mixture chemistries will clog turbine cooling holes with and without sintering thermal reactions.� Further, corrosion from salt and volcanic ash sulfates is another problem.� If melted-, or salt-fluxed sintered-, dusts accumulate on turbine vanes and blades, it leads to primary-flow blockage and notable rapid power loss events.� Protective coatings throughout the engine can become damaged extensively and rapidly from erosion and chemical reactions.� It is desired to create a flight-weight, low-volume, engine-integrated sensor system that can measure instantaneously and trending over full-engine life, the total mass, inlet loading rate, particle size distribution, compositional melting point, and salt-fractions.� It will contribute engine in-flight risk assessment to damaging events from volcanic ash and low melting temperature mixtures.� The sensor will be capable of reporting historical exposure rates and ingestion totals in all air-breathing operating environments and altitudes.

PHASE I: Conduct interviews with industry and Naval experts in engine diagnostics and safety of flight in dust or volcanic-ash laden environments.� Determine the specific detailed design options and an initial set of requirements for an operational aero-engine contaminant sensing system.� Select and evaluate the feasibility of one or more key sensing functions of the concept design.� Develop a product concept design showing how it is to be integrated on a current and/or future fleet aircraft, including locations on engines and diagnostic system interfaces.� Determine and justify needed measurement uncertainty requirements for the various measurement characteristic options.� Identify steps that will be taken in Phase II to meet the overall device specifications within a specific application context including what attributes should be included within any new context to improve either affordability, measurement fidelity, or reliability.

PHASE II: Based upon the Phase I design, deliver a prototype of the operational sand and particulate sensor system for aircraft gas turbine engines.� In a contaminated flow rig or on a contaminated small turbine engine, demonstrate that it delivers the required measurement characteristics, accuracies, and uncertainties.

PHASE III DUAL USE APPLICATIONS: Dual-use application is possible to commercial aircraft operating in volcanic regions and also austere events regions.� Ruggedize and mature the sand and particulate sensor system for a specific application context of interest to a Navy acquisition sponsor. �Consider methods to further improve affordability, measurement fidelity, and/or reliability.

REFERENCES:

1. National Research Council. �A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs�. Consensus Study Report, 2006. https://www.nap.edu/catalog/11780/a-review-of-united-states-air-force-and-department-of-defense-aerospace-propulsion-needs

2. Lekki, J., Guffanti, M., Fisher, J., Erlund, B., Clarkson, R., and van de Wall, A. �Multi-Partner Experiment to Test Volcanic-Ash Ingestion by a Jet Engine�. February, 2013. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130013612.pdf

3. MIL-STD-810G (w/ Change-1), �Department Of Defense Test Method Standard: Environmental Engineering Considerations And Laboratory Tests�. April 15, 2014. http://everyspec.com/MIL-STD/MIL-STD-0800-0899/MIL-STD-810G_CHG-1_50560/

4. Powder Technology, Inc. �Air Force Research Lab, 03 Test Dust�. http://www.powdertechnologyinc.com/product/afrl-03-test-dust/

5. Phelps, A. and Pfedderer, L. �Development of a naturalistic test media for dust ingestion CMAS testing of gas turbine engine�. ECI Symposium Series in "Thermal Barrier Coatings IV", 2015. http://dc.engconfintl.org/thermal_barrier_iv/29

6. Czugala, M., Maher, D., et al. "CMAS: fully integrated portable centrifugal microfluidic analysis system for on-site colorimetric analysis". RSC Advances. July 2013. http://doras.dcu.ie/18844/1/CMAS_fully_integrated_portable_Centrifugal.pdf

7. �Process Particle Counter (PPC) Sensor/Controller For Optimizing Power Recovery Expander And Gas Turbine Performance�. PPC Application Note, 08/06/04. http://www.processmetrix.com/research_and_development/downloads/PPC_Refinery_application.pdf

8. "The Forward Scattering Spectrometer Probe (FSSP)." Centre for Atmospheric Science, Manchester, UK.� http://www.cas.manchester.ac.uk/restools/instruments/cloud/fssp

9. United States Patent 9714967 B1. �Electrostatic dust and debris sensor for an engine�. July 25, 2017. https://www.google.com/patents/US9714967

10. United States Patent 20120068862 A1. �Systems and Methods for Early Detection of Aircraft Approach to Volcanic Plume�. March 22, 2010. https://www.google.com/patents/US20120068862

11. United States Patent 7,535,565. �System and Method for Detecting and Analyzing Compositions�. May 19, 2009. https://patentimages.storage.googleapis.com/pdfs/US7535565.pdf

12. Haldeman, C. �Small Engine and Gradient Rig Integration for CMAS and Other Environmental Pollutant Evaluation�. �Environmental Effects� session May 24th, Propulsion Safety & Sustainment Conference PS&S 2017

13. Haldeman, C. �Turbine Infrared Thermal Measurement System Development-Turbine Rig Deployment to Support Product Life Cost Reduction�. �Environmental Effects� session May 25th, Propulsion Safety & Sustainment Conference PS&S 2017

14. Murugan, M., Ghoshal, A., Walock, M., Nieto, A., Bravo, L., Barnett, B., Pepi, M., Swab, J., Pegg, R. T., Rowe, C., Zhu, D., and Kerner, K. �Microstructure Based Material-Sand Particulate Interactions and Assessment of Coating for High Temperature Turbine Blades�. Help understanding �CMAS� turbine damage: GT2017-64051. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170008019.pdf

15. Krisak, M. B. �Environmental Degradation of Nickel-Based Superalloys Due to Gypsiferous Desert Dusts�. United States Air Force Institute of Technology, AFIT-ENY-DS-15-S-066. http://www.dtic.mil/dtic/tr/fulltext/u2/a621803.pdf

16. University of Dayton Research Institute. �Particle Erosion Test Facility (Sand and Dust)�. https://www.udri.udayton.edu/NonstructuralMaterials/Coatings/Pages/ParticleErosionTestFacility.aspx

KEYWORDS: Gas Turbine; Sand-dust Sensor; Particulate Sensor; Aerosol Salt; Airborne Contaminants