Expanding the Capability of a Legacy Combustion Flame Tube to Test High-Temperature Engine Materials in Relevant Environments

Abstract

New materials and component designs are needed to advance gas turbine engine technology and provide the performance and efficiency needs for future applications. In order to advance these materials, testing in combustion environments is a critical step prior to engine testing. In this work, we detail the design and the fabrication of a materials test sector in a flame tube combustor facility. The facility simulates a combustion environment similar to that experienced by components in gas turbine engines. The flow regime is characterized by a combination of high-temperature, high-heat flux, and high-velocity that components experience in gas turbine engines. Exposure of components in this facility allows for the study of combined environmental effects and the impact on both coating and substrate durability. The test facility may operate across a wide range of pressures from 275 to 400 psig (1896–2758 kPa) and an air flowrate of 5 lb/s (2.27 kg/s). While combustion gas temperature is expected in excess of 3000 °F (1649 °C), 900 °F (482 °C) cooling air may be supplied to the backside of components or test articles. The flame tube combustor was previously used to evaluate fuel injectors and combustion products, and the new test configuration will also allow for materials exposure to complex, engine-like conditions. The interior of the test section was additively manufactured from GRCop-84 and cryogenically fit and brazed to a stainless-steel 304 housing. The use of a copper liner minimizes welds and, with active cooling, is expected to provide better durability over traditional hardware using stainless-steel or Inconel with a ceramic liner. The test section has two opposing 9.5 in × 3.125 in (241 mm × 80 mm) removable windows that can accommodate articles up to 3.5 in (89 mm) tall. This modular design allows for custom platforms to hold coupons, panels, or airfoil shapes to be tested with minimal re-engineering or fabrication. The bolted joint and sealing remains consistent, so any new testing only needs to work within the existing design footprint. This paper will provide an overview of the facility capabilities, design considerations, as well as thermal and structural analysis of the hardware. Future testing of ceramic matrix composite (CMC) airfoils and advanced environmental barrier coatings (EBCs) will also be discussed.