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Rapid mix concepts for low emission combustors in gas turbine enginesNASA LeRC has identified the Rich burn/Quick mix/Lean burn (RQL) combustor as a potential gas turbine combustor concept to reduce NOx emissions in High Speed Civil Transport (HSCT) aircraft. To demonstrate reduced NOx levels, NASA LeRC soon will test a flametube version of an RQL combustor. The critical technology needed for the RQL combustor is a method of quickly mixing combustion air with rich burn gases. Two concepts were proposed to enhance jet mixing in a circular cross-section: the Asymmetric Jet Penetration (AJP) concept; and the Lobed Mixer (LM) concept. In Phase 1, two preliminary configurations of the AJP concept were compared with a conventional 12-jet radial-inflow slot design. The configurations were screened using an advanced 3-D Computational Fluid Dynamics (CFD) code named REFLEQS. Both non-reacting and reacting analyses were performed. For an objective comparison, the conventional design was optimized by parametric variation of the jet-to-mainstream momentum flux (J) ratio. The optimum J was then employed in the AJP simulations. Results showed that the three-jet AJP configuration was superior in overall mixedness compared to the conventional design. However, in regards to NOx emissions, the AJP configuration was inferior. The higher emission level for AJP was caused by a single hot spot located in the wake of the central jet as it entered the combustor. Ways of maintaining good mixedness while eliminating the hot spot were identified for Phase 2 study. Overall, Phase 1 showed the viability of using CFD analyses to evaluate quick-mix concepts. A high probability exists that advancing mixing concepts will reduce NOx emissions in RQL combustors, and should be explored in Phase 2, by parallel numerical and experimental work.
Document ID
19910009735
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Talpallikar, Milind V. (CFD Research Corp. Huntsville, AL., United States)
Smith, Clifford E. (CFD Research Corp. Huntsville, AL., United States)
Lai, Ming-Chia (Wayne State Univ. Detroit, MI., United States)
Date Acquired
September 6, 2013
Publication Date
October 1, 1990
Subject Category
Aerodynamics
Report/Patent Number
NASA-CR-185292
NAS 1.26:185292
Accession Number
91N19048
Funding Number(s)
CONTRACT_GRANT: NAS3-25834
PROJECT: RTOP 537-02-11
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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