Numerical Investigation of Bluff-Body Configurations for Enhanced Hydrogen Combustion Performance

Abstract

Abstract. This study investigates the effects of bluff-body geometries and hydrogen fractions on the combustion performance of non-premixed methane–hydrogen flames. Using computational fluid dynamics (CFD), the impact of varying hydrogen fractions (0%, 20%, 40%, 60%, 80%, and 100%) in a methane–hydrogen fuel mixture and bluff-body angles (20 deg, 40 deg, and 60 deg) on velocity profiles, temperature distributions, Damköhler number profiles, OH and emissions (CO and NOx) is analyzed. Results show that increasing hydrogen fractions results in a more concentrated velocity core and higher peak temperatures, leading to shorter, more compact flames with improved combustion efficiency. Bluff-body angles influence recirculation zones, which enhance flame stability and mixing, with larger angles expanding these zones and improving flame stabilization. A noticeable shift in flame centerline temperature and velocity field is observed beyond 40% hydrogen, while 20% hydrogen fraction in methane has minimal effect, indicating limited impact on combustion dynamics. Larger bluff-body angles result in increased turbulence levels and raised temperature levels, whereas higher hydrogen fractions produce more compact flames with reduced temperature variations. Hydrogen-enriched flames exhibit lower NOx and CO emissions due to shortening nitrogen's exposure to high temperatures and enhancing combustion efficiency. Furthermore, replacing methane with hydrogen significantly reduces CO2 emissions, but the cost of hydrogen exceeds the value of carbon credits. This highlights the need for more affordable hydrogen production and higher carbon credit prices to make hydrogen a financially viable option for widespread adoption.