High-Momentum Jet Flames at Elevated Pressure, C: Statistical Distribution of Thermochemical States Obtained From Laser-Raman Measurements

Abstract

A detailed investigation on flame structures and stabilization mechanisms of confined high momentum jet flames by 1D-laser Raman measurements is presented. The flames were operated with natural gas (NG) at gas turbine relevant conditions in an optically accessible high pressure test rig. The generic burner represents a full scale single nozzle of a high temperature FLOX® gas turbine combustor including a pilot stage. 1D-laser Raman measurements were performed on both an unpiloted and a piloted flame and evaluated on a single shot basis revealing the thermochemical states from unburned inflow conditions to burned hot gas in terms of average and statistical values of the major species concentrations, the mixture fraction and the temperature. The results show a distinct difference in the flame stabilization mechanism between the unpiloted and the piloted case. The former is apparently driven by strong mixing of fresh unburned gas and recirculated hot burned gas that eventually causes autoignition. The piloted flame is stabilized by the pilot stage followed by turbulent flame propagation. The findings help to understand the underlying combustion mechanisms and to further develop gas turbine burners following the FLOX® concept. Together with the connected papers A, B and D, the results form a unique and comprehensive data set for the validation of numerical simulation models.

Numerical Simulation of a High Momentum Jet Flame at Elevated Pressure: A quantitative Validation with Detailed Experimental Data

“…One operating point which is investigated experimentally by , Severin et al (2017), Ax et al (2019) and Nau et al (2018) is chosen from the experimental data. It represents the case with the most comprehensive data set.…”

“…It represents the case with the most comprehensive data set. The chosen operating point corresponds to case U described in Severin et al (2017) and Ax et al (2019). Natural gas with a CH 4 content of 92.5-95.8% is used as fuel for this operating point .…”

“…The model combustor investigated is based on a FLOX® burner and operates at gas turbine relevant conditions. The combustion chamber is optically accessible and well characterized by experiments conducted at the high pressure test rig HBK-S at the Institute of Combustion Technology at the German Aerospace Center (DLR) Severin et al, 2017;Nau et al, 2018;Ax et al, 2019;Schäfer et al, 2019).…”

“…By comparing the simulations conducted the influence of the combustion chamber wall temperature on the combustion process is also investigated. Detailed flow field data resulting from Particle Image Velocimetry (PIV) (Severin et al, 2017) and Laser-Raman (Ax et al, 2019) measurements are used to verify the simulation results.…”

Numerical Investigation of a High Momentum Jet Flame at Elevated Pressure: A Quantitative Validation with Detailed Experimental Data

“…The model combustor investigated is based on a FLOX® burner and operates at gas turbine relevant conditions. The combustion chamber is optically accessible and well characterized by experiments conducted at the high pressure test rig HBK-S at the Institute of Combustion Technology at the German Aerospace Center (DLR) Severin et al, 2017;Nau et al, 2018;Schäfer et al, 2019;Ax et al, 2020).…”