Suppression of NOx Emission of a Lean Staged Combustor for an Aircraft Engine

Fujiwara, Hitoshi; Matsuura, Kazuaki; Shimodaira, Kazuo; Hayashi, Shigeru; Kobayashi, Masayoshi; Oda, Takeo; Horikawa, Atsushi; Matsuyama, Ryusuke; Ogata, H.; Kinoshita, Yasuhiro

doi:10.1115/gt2011-46256

Cited by 6 publications

(3 citation statements)

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“…Because of the possibility of controlling NO x emissions at a very low level, the lean premixed staged combustion is often applied by most manufacturers to replace the traditional diffusion combustion. 3,4 The lean premixed combustor developed by Rolls-Royce, 5–7 General Electric 8,9 and JAXA 10–12 have been widely used to meet the requirements of low emission. The fuel and the oxidant are premixed first when lean premixed combustion technology is adopted.…”

Section: Introductionmentioning

confidence: 99%

The effects of swirl number on the combustion characteristics in an internally-staged combustor

Zhao

Liu

Zhang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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The three-dimensional turbulent swirling flame in an internally-staged combustor is numerically investigated. Four cases over a range of swirl intensities are explored by the Flamelet Generated Manifold model in this paper. Special attention is paid to analyzing the variation of the flow field, temperature, major species concentrations and emissions. The results clearly show the effects of swirl number on the size of the center recirculation zone, fuel distribution and combustion characteristics. When the third premixed stage swirl number increases from 0.6 to 1.2, the axial length of the center recirculation zone decreases by 3.7%, while the radial length increases by 6.9%. The characteristics of the flow field play an important role in the spatial distribution of the fuel, which further affects the temperature distribution in the combustor. The backflow effect is enhanced, resulting in a greater concentration of fuel at the outlet of the swirler. After the maximum temperature is reached at the exit position of the pilot stage, the temperature decreases compared to the peak temperature downstream as the proportion of premixed combustion mode increases. This creates a high concentration region of OH at the outlet of the pilot stage injector and the heat release region is squeezed upstream. At the same time, the volume of the high-temperature region downstream of the pilot stage is reduced. In addition, as the swirl number of the third premixed stage increases from 0.6 to 1.2, the emissions of NO and CO decrease by 28.7% and 75%, respectively.

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Section: Introductionmentioning

confidence: 99%

The effects of swirl number on the combustion characteristics in an internally-staged combustor

Zhao

Liu

Zhang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Then the two injectors had been tested on realistic altitude relight conditions, which demonstrated comparable altitude relight characteristics. 13 Kobayashi et al 14,15 developed a lean staged combustor, which selected prefilm atomizer as the pilot fuel nozzle. The key design parameters of this injector were experimentally examined on ignition stability, and results indicated that concentrated fuel distribution in the central recirculation zone was beneficial for the flame stability.…”

Section: Introductionmentioning

confidence: 99%

The quantitative characterization of the ignition process for a lean staged injector: Influence of the air split between pilot swirlers

Yang

Liu

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part G:

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The ignition of a lean staged injector aimed at aeronautical application is a transient and complex phenomenon, which involves fluid dynamics, turbulent mixing, chemical kinetics, as well as their mutual interactions. In the present research, a staged injector, designed based on stratified partially premixed combustion concept, is introduced. The ignition performance of stratified partially premixed injectors with different air split ratios between pilot swirlers are experimentally acquired, which exhibits apparent distinctions. In order to make quantitative analyses, the classical physical ignition model is improved, in which the flame propagation process is further divided into the axial and radial propagation sub-processes. Nonreacting flow field and discrete phase simulations, validated by experiment results, are utilized to obtain the velocity and spray distributions. Physical parameters characterizing the ignition sub-processes are defined and calculated based on the numerical simulation results. Conclusions are made by comparing the physical parameters of the ignition sub-processes. The radial propagation of the ignition kernel is responsible for the ignition performance difference between the two injectors with different pilot air split ratios (PASR) in that the average equivalence ratio along the radial propagation route of PASR = 7:3 is one order richer than that of PASR = 2:8. The present ignition analysis and model can be further extended and developed for the optimization of ignition performance of lean staged injector.

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“…For reduction of NOx from aircrafts, coaxial-staging lean burn fuel injection systems have been studied intensively these days [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] and some of them have been already in service. Typically, they consist of a non-premixedmode pilot nozzle at the center for flame stability and a lean premixed-mode main nozzle surrounding the pilot for drastic NOx reductions.…”

Section: Introductionmentioning

confidence: 99%

Visualization of pilot flame of an optically-accessible coaxially-staged aero-engine lean-burn fuel injector

Matsuura

Uesaka

Iwasaki

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The visualization of the pilot flame of a coaxially-staged aero-engine lean-burn fuel injector, not only downstream but also inside of the pilot nozzle, was successfully performed at realistic aero-engine conditions. Optical access toward the inside of the nozzle was achieved through the inner and outer shrouds, both of which were made of transparent quartz. The image distortion caused by complex contours of the two shrouds was corrected by a method based on optical ray tracing, which realized precise determination of spatial intensity distribution of optical signals. Line-of-sight OH chemiluminescence, cross-sectional OH-LIF, kerosene LIF and kerosene Mie scattering were employed as diagnostic tools. The effects of pilot local air-to-fuel ratio on spray flame structure were revealed, both inside and downstream of the pilot nozzle under stable combustions. As the pilot mixture got rich, the main reaction zone moved from inside of the pilot nozzle to the region near the injector lip downstream of the injector exit. The OH-LIF signal was detected near the central axis surrounded by the fuel spray. It was also observed near the back-step of the pilot nozzle for the rich cases. The experiments under combustion oscillation were also conducted and the correlation of phenomena inside and downstream of the pilot nozzle was captured. It was clarified that the reaction enhancement in the outer part of the lip vortex region was caused by the convection of rich mixture, which appeared near the pilot atomizer lip at 150~210deg earlier oscillation phase angle. KeywordsAero-engine combustor, Optical burner/injector, Staged lean-burn injector, Laser induced fluorescence, Ray tracing, Optical refraction correction, Elevated temperature and pressure IntroductionFor reduction of NOx from aircrafts, coaxial-staging lean burn fuel injection systems have been studied intensively these days [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] and some of them have been already in service. Typically, they consist of a non-premixedmode pilot nozzle at the center for flame stability and a lean premixed-mode main nozzle surrounding the pilot for drastic NOx reductions. For such an injector, both fuel injection and fuel/air mixing start a few centimeter upstream from the injector exit (i.e. entrance of the combustion chamber). Moreover, this is also true for its pilot flame. Therefore, many important phenomena take place in regions enclosed by the metal walls of the injector, where the application of optical diagnostics is not straightforward compared with a conventional combustor. In our previous work, visualization of fuel spray/vapor behavior and fuel/air mixing inside the main nozzle (i.e. the premixing duct) was performed by high speed visualization and/or LIF techniques [10,11,15]. Through a fullycontoured quartz-made transparent outer-shroud, dynamic motion of fuel sprays under combustion oscillations at an elevated pressure and temperature was clearly captured and discussed in relation to the flame dynamics downstream [15]. ...

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Suppression of NOx Emission of a Lean Staged Combustor for an Aircraft Engine

Cited by 6 publications

References 0 publications

The effects of swirl number on the combustion characteristics in an internally-staged combustor

The effects of swirl number on the combustion characteristics in an internally-staged combustor

The quantitative characterization of the ignition process for a lean staged injector: Influence of the air split between pilot swirlers

Visualization of pilot flame of an optically-accessible coaxially-staged aero-engine lean-burn fuel injector

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