Abstract
Three different structures of a new dual fuel nozzle design concept (inner swirl nozzle, double swirl nozzle, and outer swirl nozzle) were developed for the chemically recuperated gas turbine (CRGT) combustor. The combustion flow fields in the combustor with the three nozzles were investigated, respectively, based on the FLUENT simulation. The realizable <svg style="vertical-align:-0.13794pt;width:8.6750002px;" id="M1" height="12.4375" version="1.1" viewBox="0 0 8.6750002 12.4375" width="8.6750002" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,12.162)"><path id="x1D458" d="M480 416q0 -21 -18 -41q-9 -11 -17 -7q-20 9 -42 9q-62 0 -140 -78q23 -69 88 -192q17 -31 27 -42t20 -11q16 0 62 46l17 -20q-64 -92 -119 -92q-35 0 -70 66q-41 73 -84 187q-36 -30 -62 -61q-27 -115 -35 -172q-41 -8 -78 -20l-6 6l140 612q7 28 0.5 34t-37.5 7l-34 1
l5 26q38 4 74 13.5t57 17t25 7.5q12 0 4 -32l-104 -443h2q35 38 97 93q39 35 65.5 56t62 41.5t58.5 20.5q19 0 30.5 -10t11.5 -22z" /></g> </svg>-<svg style="vertical-align:-0.13794pt;width:7.0999999px;" id="M2" height="7.9499998" version="1.1" viewBox="0 0 7.0999999 7.9499998" width="7.0999999" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path id="x1D700" d="M387 375q0 -16 -17 -31t-29 -15q-9 0 -12 13q-13 74 -80 74q-36 0 -61 -24.5t-25 -56.5t24 -51.5t68 -19.5q33 0 47 2l2 -7l-32 -42q-20 2 -54 2q-45 0 -74 -21.5t-29 -60.5q0 -41 28 -65.5t73 -24.5q78 0 145 67l17 -23q-33 -47 -84.5 -75t-111.5 -28q-70 0 -114.5 35.5
t-44.5 92.5q0 46 38 78t95 45v2q-35 10 -54.5 33t-19.5 52q0 55 53 88.5t122 33.5q67 0 98.5 -23.5t31.5 -49.5z" /></g> </svg> model and PDF model were adopted, respectively, for the turbulence flow and nonpremixed reformed gas combustion. The obtained results using these models showed good agreement with experimental results in original oil combustor. The effects of different dual fuel nozzle structures on the flow field, fuel concentration distribution, and temperature distribution in the combustor were simulated and analyzed. Results suggest that the double swirl nozzle and outer swirl nozzle can form a better flow field with obvious central recirculation zone (CRZ), shorten fuel and air mixing distance, and obtain a more uniform outlet temperature distribution, in comparison with the inner swirl nozzle. However, compared with double swirl nozzle, the outer swirl nozzle can result in a better combustion flow field with the high temperature region in the CRZ, which is important to stabilize the flame.
Highlights
Since gas turbine is compact, lightweight, quick starting, highly reliable, and simple to operate, it has been used widely for many years in aviation, shipping, electric power, fossil oil, and other industrial fields [1]
In the outer swirl nozzle or double swirl nozzle combustor, there is a counter-rotating vortex pair forming in the primary zone of the combustor, which is the main characteristic of the central recirculation zone (CRZ)
The CRZ can provide the heat source by upstream convection and mixing of hot reaction products with a fresh charge of fuel and air, and reduce the mixture velocity to be in the range of flame speed which is necessary for flame stabilization
Summary
Since gas turbine is compact, lightweight, quick starting, highly reliable, and simple to operate, it has been used widely for many years in aviation, shipping, electric power, fossil oil, and other industrial fields [1]. Zhen et al [7] performed an experiment study to investigate the effects of the nozzle length on the emission of a burner utilizing a multi-fuel-jet inverse diffusion flame. They found that the flame centerline temperature and CO/CO2 concentrations were significantly affected by the nozzle length. In order to burn the reformed gas effectively, three different structures of a new dual fuel nozzle design concept were developed. The effects of different dual fuel nozzle structures on the flow field, fuel concentration distribution, and temperature distribution in the combustor were discussed. This work could help improve the design of the dual fuel nozzle for the CRGT combustor and save experiment cost
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