High Momentum Jet Flames at Elevated Pressure: B — Detailed Investigation of Flame Stabilization With Simultaneous PIV and OH-LIF

Abstract

A model FLOX ® combustor, featuring a single high momentum premixed jet flame, has been investigated using laser diagnostics in an optically accessible combustion chamber at a pressure of 8 bar. The model combustor was designed as a large single eccentric nozzle main burner (Ø 40 mm) together with an adjoining pilot burner and was operated with natural gas.To gain insight into the flame stabilization mechanisms with and without piloting, simultaneous Particle Image Velocimetry (PIV) and OH Laser Induced Fluorescence (LIF) measurements have been performed at numerous two-dimensional sections of the flame. Additional OH-LIF measurements without PIV-particles were analyzed quantitatively resulting in absolute OH concentrations and temperature fields.The flow field looks rather similar for both the unpiloted and the piloted case, featuring a large recirculation zone next to the high momentum jet. However, flame shape and position change drastically. For the unpiloted case, the flame is lifted, widely distributed and isolated flame kernels are found at the flame root in the vicinity of small scale vortices. For the piloted flame, on the other hand, both pilot and main flame are attached to the burner base plate, and flame stabilization seems to take place on much smaller spatial scales with a connected flame front and no isolated flame kernels.The single shot analysis gives rise to the assumption that for the unpiloted case small scale vortices act like the pilot burner flow in the opposed case and constantly impinge and ignite the high momentum jet at its root.

Wall Temperature Measurements in Gas Turbine Combustors With Thermographic Phosphors

“…Temperatures increase along the x-axis and the maximum is slightly asymmetric along the y-axis due to the location of the main nozzle at y = −10 mm. The temperature field is in qualitative agreement with the flame location obtained from OH * chemiluminescence and with gas temperatures obtained from OH-LIF measurements [24,25]. Temperature measurements on the quartz walls were challenging for two reasons: Interfering fluorescence, probably from the quartz, and window degradation, especially for temperatures above 1400 K. It should be noted that these problems were not associated with the measurements on the ceramic probe mentioned above, where measurements up to 1700 K were possible.…”

“…Temperatures on the quartz walls were measured for case U described in Severin et al [25] (λ = 1.83) and complement existing measurements from particle image velocimetry (PIV) and OH laser induced fluorescence (LIF). The phosphor (YAG:Eu and YAG:Dy) was coated at several positions as 4 × 4 mm 2 square points using the HPC binder.…”

“…The experiments were carried out at the high pressure test rig HBK-S at DLR Stuttgart. Because the FLOX ® combustor used here has been discussed in detail in previous publications, only a brief desciption is given here [24,25]. This burner was designed to provide a fuel-flexible combustor (gaseous and liquid fuels) to gain deeper insight into jet stabilized flames with or without a pilot flame.…”

Numerical Simulation 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;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.…”