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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

# Laboratory Study of Premixed $H2$-Air and $H2–N2$-Air Flames in a Low-Swirl Injector for Ultralow Emissions Gas Turbines

[+] Author and Article Information
R. K. Cheng, D. Littlejohn

Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

The linear dependency of $ST$ on $u′$ is not universal as $ST$ in other burners tends to be nonlinear and shows “bending.”

J. Eng. Gas Turbines Power 130(3), 031503 (Apr 02, 2008) (9 pages) doi:10.1115/1.2836480 History: Received May 09, 2007; Revised September 17, 2007; Published April 02, 2008

## Abstract

The objective of this study is to conduct laboratory experiments on low-swirl injectors (LSIs) to obtain the basic information for adapting LSI to burn $H2$ and diluted $H2$ fuels that will be utilized in the gas turbines of the integrated gasification combined cycle coal power plants. The LSI is a novel ultralow emission dry-low $NOx$ combustion method that has been developed for gas turbines operating on natural gas. It is being developed for fuel-flexible turbines burning a variety of hydrocarbon fuels, biomass gases, and refinery gases. The adaptation of the LSI to accept $H2$ flames is guided by an analytical expression derived from the flow field characteristics and the turbulent flame speed correlation. The evaluation of the operating regimes of nine LSI configurations for $H2$ shows an optimum swirl number of 0.51, which is slightly lower than the swirl number of 0.54 for the hydrocarbon LSI. Using particle image velocimetry (PIV), the flow fields of 32 premixed $H2$-air and $H2–N2$-air flames were measured. The turbulent flame speeds deduced from PIV show a linear correlation with turbulence intensity. The correlation constant for $H2$ is 3.1 and is higher than the 2.14 value for hydrocarbons. The analysis of velocity profiles confirms that the near field flow features of the $H2$ flames are self-similar. These results demonstrate that the basic LSI mechanism is not affected by the differences in the properties of $H2$ and hydrocarbon flames and support the feasibility of the LSI concept for hydrogen fueled gas turbines.

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## Figures

Figure 1

The first prototype LSI for Taurus 70 engine

Figure 2

Schematics of the LSI setup

Figure 3

Operating regime of LSI-R for H2

Figure 4

Operating maps of LSIs with UH center plates

Figure 5

Operating maps of LSIs with UH center plates

Figure 6

Normalized 2D velocity vectors and normalized shear stresses measured in nonreacting flows of U0=18m∕s in (a) LSI-R and (b) LSI-VH1 and in H2∕air flames of ϕ=0.35 and U0=18m∕s in (c) LSI-R and (d) LSI-VH. Dashed lines mark the leading edges of the flame brushes.

Figure 7

Comparison of the turbulent flame speed ST of H2 and hydrocarbon flames

Figure 8

Nondimensionalized axial aerodynamic stretch rate ax measured in the nonreacting (a) and reacting (b) flow fields of the LSIs

Figure 9

Virtual origin x0 deduced for the nonreacting (a) and reacting (b) flow fields of the LSIs

Figure 10

Centerline velocity profiles of H2 flames by LSI-VH1

Figure 11

Radial profiles at x=12mm of H2 flames by LSI-VH1

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