Design and Evaluation of a Lean-Premixed Hydrogen Injector with Tangential Entry in a Sector Combustor

Abstract

Hydrogen use in a gas turbine engine has many benefits. Chief among these is the elimination of carbon based emissions. The only products and emissions from the combustion process are water vapor and oxides of nitrogen (NOx). However due to the lower flammability limit of hydrogen, it can be burned at much lower equivalence ratios that typical hydrocarbon fuels, and thus reducing the emissions of NOx. Multiple efforts have been made for the design of premixing injectors for gaseous hydrocarbon fuels, but very few attempts have been made for hydrogen.

To this end a premixing hydrogen injector was designed for the cruise engine condition for a PT6-20 turboprop engine. Swirl generated by tangential entry was utilized as a means to enhance mixing and as a convenient means to stabilize the flame. A prototype was designed to prevent flashback and promote a high degree of mixing, as well as a test combustor to evaluate the performance of the injector at scaled engine conditions. Numerical simulations were also performed to analyze the flowfield at the engine conditions. Performance and emissions data are used to draw conclusions about the feasibility of the injectors in the PT6 engine.