Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150172

150172 - Effect of Exhaust Gas Recirculation on Laminar Burning Velocity and Intrinsic Cellular Instabilities for a Hydrogen Sequential Stage Gas Turbine Combustor 

Often referred to as a fuel of the future, hydrogen has gained significant attention in recent years since the advancement of current power generation systems is constrained by limited energy resources and increasing regulations on emissions. Unlike conventional hydrocarbon fuels, hydrogen combustion generates zero-carbon, making it a promising solution in the fight against climate change. Additionally, hydrogen can be generated through electrolysis powered by renewable wind or solar systems using the excess energy during the generation surplus, with the potential to store hydrogen for medium to long term energy storage cycles i.e., Power-to-Gas H2.

The use of hydrogen, coupled with sequential staged combustion can enable a reduction in NOx emissions and decarbonized energy for gas turbine engines. Major initiatives are underway to achieve 100% hydrogen powered turbines in the gas turbine industry by 2030. The essential feature of sequential two-stage combustors is that combustion takes place in two successive stages in series at nearly the same pressure. Autoignition of the hydrogen/air/residual mixture and propagation of the flame stabilizes the flame in the second combustion stage. However, the existence of post combustion products in the second combustion stage affects the stability and reactivity of the flame. The reactivity, exothermicity, and essential flame/combustion stability characteristics, such as blowoff, blowout, flashback, and liftoff, of a combustible mixture are associated with the laminar burning velocity of the fuel.

 To investigate the effect of the post combustion products on the combustion of the H₂/air mixture in the second combustion stage, laminar burning velocity measurements were performed using a constant volume combustion vessel of hydrogen/air mixtures diluted with exhaust gases. A mixture of 35 % H₂O+ 65 % N₂, by mole, was used to represent the actual combustion products from the first stage with dilution ratios of 0-40%, by volume. The measurements were performed at 3 bar, 373-473K, and equivalence ratios of 0.7-1.0. High speed schlieren imaging was used to capture the flame propagation and the data was used to investigate the instability cellularity characteristics of the flame.  The experimental measurements show that the flame speed decreases almost linearly with increased dilution levels. 1-D chemical kinetic simulations were combined with experimental measurements to quantify the effect of EGR on the flame thickness, Lewis number and expansion ratio across the flame. The mean cell area and number of cells were also calculated from the collected experimental data. Results show that adding higher levels of EGR dilution can enhance the flame hydrodynamic stability.

Presenting Author: Ahmed Barain Michigan State University

Presenting Author Biography: I am Ahmed Barain, a research assistant at the Mechanical Power Engineering Department, Michigan State University- East Lansing-USA.
My work is focused on alternative fuels. During my master studies, I investigated the atomization process of Jatropha biofuel for aviation applications. I am currently investigating the burning velocities and ignition delay times of diluted hydrogen/air mixtures for gas turbine applications.

Authors:

Elisa Toulson Michigan State University
Ahmed Barain Michigan State University