摘要:

The blowoff and liftoff characteristics of lifted turbulent diffusion flames of liquefied petroleum gas and compressed natural gas are investigated with a range of burner diameters. Uninhibited flames as well as flames inhibited by either Bromotrifluoromethane, (CF3Br known as Halon-1301), N2or Ar have been studied. The coflowing air stream is set at about 42cm/s. The inhibitor is either premixed with the fuel or introduced externally in the air stream via a circular injector positioned at the jet exit plane. The flames are videotaped and subsequently analysed.

ISSN:0010-2202    

DOI:10.1080/00102209508907758

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The prediction of nitric oxide (NO) formation in turbulent flames requires a modelling approach that takes into account the coupled nature of local turbulent mixing and chemical reaction. The Conditional Moment Closure (CMC) and Probability Density Function (PDF) methods have been developed to include these interactions, and have been applied in this case to predict NO formation in a turbulent nonpremixed hydrogen jet flame with a Reynolds number of 10000.

ISSN:0010-2202    

DOI:10.1080/00102209508907759

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A post-transitional, spatially-developing, exothermically reacting shear-layer is simulated using the transport-element method. The scheme, which solves the unaveraged, time-dependent coupled scalar-transport and Navier-Stokes equations, in their gradient and vorticity transport forms, respectively, is Lagrangian, grid-free and adaptive. The Shvab- Zeldovich formulation is exploited to provide solutions for both moderately fast and infinitely fast reactions. In the case of a finite reaction rate, Arrhenius kinetics are assumed. Numerical results are used to evaluate the effectiveness- with respect to predicting the dynamic effects of combustion exothermicity on the flow- of the infinite reaction rate model in approximating finite reaction rate combustion. Results indicate that as long as the reaction is last compared to the flow and abrupt non-equilibrium transient phenomena, such as quenching, are avoided, the computationally more efficient infinite reaction rate model offers a reasonable substitute of its finite reaction rate counterpart. For both models the externally-forced flow growth rate is reduced in the presence of combustion exothermicity through the alteration of the mechanism of interaction of the vortical structures from paring to tearing and the alignment of the eddy larger dimension with the streamwise direction. By comparing cases with different enthalpies of reaction we show that the performance of the infinite reaction rate model improves as the Damkohler number is raised.

ISSN:0010-2202    

DOI:10.1080/00102209508907760

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor