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Advanced Ceramic Matrix Composite Gas Turbine Engine Research Combustor

Description:

TECHNOLOGY AREA(S): Air Platform 

OBJECTIVE: Explore, fabricate and evaluate ceramic matrix composite combustor research prototype for gas turbine engine and other air breathing propulsion applications, using advanced innovative design and manufacturing methods, to identify and mitigate SiC-SiC ceramic matrix composite materials and manufacturing vulnerabilities for CMC combustor operating in austere environments. 

DESCRIPTION: To meet the demands of current and future requirements, military gas turbine engines (GTEs) are required to operate at ever higher temperatures. Current engine temperatures can exceed 1500 °C, with future engines projected to exceed 2000 °C. Implementation of Silicon Carbide (SiC-SiC) ceramic matrix composite (CMCs) components including CMC combustor in propulsion engines of interest to the US Army is now a tangible reality, representing the most fundamental change in design and manufacturing practices for gas turbine engines since the introduction of single-crystal superalloys [1]. Advanced CMCs offer significant advantages over the current set of superalloy-based systems, but these materials can be brittle and will degrade over time, due to high temperature creep, thermal shock and cyclic thermomechanical loads. Specific innovation research focus areas include increased thermomechanical durability, increased resistance to environmental interactions, cost-effectiveness of processing and manufacturing, and improved approaches to CMC combustor component fabrication and integration. Computational tools and integrated experimental/computational methods are sought, including models/tools to predict degradation and failure mechanisms within CMC combustor. Application of SiC-based CMCs in combustion environments for gas turbine engine combustors operating at 1310° C or higher require significant scientific advancement in the SiC-SiC CMC material system. Unfortunately, exposures of these materials to high temperature combustion environments limit the effectiveness of thermally grown silica scales in providing protection from oxidation and component recession during service. The nature of the SiC based ceramic recession issue dictates that the combustor material system must provide prime reliant performance to ensure full component lifetime [1-13]. Thus the CMC combustor requires SiC-SiC bulk material system with improved state of the art thermal/environmental barrier coatings (EBCs) for limiting oxygen/water vapor transport, and high temperature phase stability, integration with metallic engine components mitigating thermal coefficient of expansion mismatch and optimized effusion combustion liner holes. 

PHASE I: Research and formulate innovative CMC combustor analysis and design methods leading to the development of affordable, high speed with high throughput manufacturing of SiC-SiC ceramic matrix composite materials for gas turbine combustors. Beyond a combination or standalone SiC-SiC manufacturing methods such as conventional chemical vapor deposition, pyrolysis infiltration process, and melt infiltration process, explore advanced manufacturing processes of CMC components including additive manufacturing methods and Field Assisted Sintering Technologies (FAST). Perform combined computational fluid dynamics and computation structural dynamics modeling and high fidelity simulation of CMC combustor concepts under combined effects of aerodynamic, thermal, combustion chemical reactance and structural loads. Using the proposed advanced manufacturing processes and preliminary design, fabricate at least three prototype curved CMC specimens with embedded impingement holes and thermal/environmental barrier coating and subject to at least 20 hot/cold two hour duration thermal cycles of steady-state combustion flame temperature of 1482 deg Celsius or higher to identify potential CMC material vulnerabilities at combustion temperatures. Post-test material characterization of the CMC curved specimens will be performed to identify any manufacturing defects and material degradation due to thermal cycling. Prototype ceramic matrix composite coupons will be delivered to CCDC Army Research Laboratory (ARL) for high temperature strength testing, fluid flow characterization, and microstructure analysis. A preliminary research grade CMC combustor analysis and design shall be conceived and delivered to CCDC – ARL at the end of Phase I. 

PHASE II: Explore, develop and validate the innovative SiC-SiC CMC research combustor using design and fabrication approaches of Phase I. Partnership with an Original Equipment Manufacturer (OEM) of gas turbine engine is encouraged. The proposer shall conduct high fidelity modeling and design analysis of the research grade CMC combustor prototype (e.g. representative medium lift rotorcraft turboshaft engine combustor prototype) including computational thermal fluid structural analysis with conjugate heat transfer methods to develop the combustor pattern factor and identify potential hotspot and highly stressed zones. Explore innovative methods for SiC-SiC CMC component integration with hot metal superalloys and advanced manufacturing of optimized embedded impingement and effusion holes within the combustor liners with thermal/environmental barrier coatings. Fully instrumented jet burner rig ground based experimental tests need to be conducted on the CMC combustors at CCDC-ARL Hot Particulate Ingestion Rig (HPIR) or another federal government or industry test facility subject to thermal cycling of at least 100 hot/cold two hour duration thermal cycles of steady-state flame temperature of 1550 deg Celsius or higher to identify CMC combustor material state vulnerabilities at engine relevant austere environment and explore possible mitigation solutions. The proposer shall perform pre and post experimental test nondestructive evaluation of the CMC combustor and post-test material characterization of the CMC combustor material system to explore and identify embedded defects including fiber and matrix cracks, identify zones of SiC fiber agglomeration, SiC matrix silica pools, large void spaces within the CMC substrate, and durable interphase materials. The proposer will research methods to alleviate the aforementioned possible defects in CMC combustor material system. Additionally, ceramic matrix composite combustor prototype(s) will be delivered to the CCDC - ARL for further full field high temperature characterization and research development including CMC microstructure analysis and further enhancement. 

PHASE III: The proposer will partner with an Engine OEM and conduct validation testing including full scale engine ground testing. The CMC combustor technology can be transitioned as prototype CMC combustor for a medium size rotorcraft turboshaft engine to PM Advanced Turbine Engine, PEO Aviation, Huntsville and CCDC – Aviation and Missile Center at Corpus Christi, TX. The end result of this research effort will be a validated approach for development of CMC Combustor transitioned to medium size future vertical aircraft propulsion system. 

REFERENCES: 

1: Ghoshal, A., Murugan M., Nieto, A., Walock, M. J. et al, "High Temperature Ceramic Matrix Composite Materials Research for Next Generation Army Propulsion System"

KEYWORDS: Ceramic Matrix Composite Materials, SiC-SiC (Silicon Carbide - Silicon Carbide), CMC Combustor Design, Interphase Layer, Jet Burner Rig Test 

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