CMC Combustor Demonstration in a Small Helicopter Engine

Silicon-based ceramics are attractive materials for use in gas turbine engine hot sections due to their high temperature mechanical and physical properties as well as lower density than metals.   Ceramic matrix composite (CMC) hot section components offers the potential elimination of the film cooling to provide reduced emissions and increased durability.  The high temperature capability of a CMC combustor is expected to increase the life of the combustor while enabling the elimination of film cooling and a reduction of combustor cooling.  In addition, the profile of the combustion gas entering the turbine is predicted to improve which will increase the life of turbine components.  Further improvements in the CO, NOx and smoke emissions are projected.

UTRC and P&W Canada partnered to demonstrate an advanced combustor configuration that was enabled by high temperature CMC materials, in a PW200 series combustor.  The PW200 series have reverse flow combustors and the program presented significant challenges in design and fabrication.  The advanced CMC configuration was successfully tested in a PW206 combustor rig.  At full power, a 40-50% reduction in pattern factor relative to the bill-of-material metal combustor was measured.  The combustor exit plane temperatures were generally better mixed due to the combined effects of (1) eliminating the cold film layers near the combustor walls and (2) the increase in fuel injector count enabled by the increase in dilution air.  The CMC combustor was also successfully tested in an engine configuration.  Post test gas path surfaces of the EBC coated CMC combustor components were in good condition.