摘要:

Heterogeneous reaction is considered to be main mechanism in desulfurization from the flue gas by low temperature plasmas. The radical SO3 plays a major part in oxidizing sulfiteions to sulfate ions in reference to Huie's proposal. Solving the kinetic equationsreveals that the hydroxyl radicals absorbed in the liquid phase may contribute over 85% of desulfurization rate. which is over ten times of that due to gas phase reactions. The predicted area factor effect is proved by the experiments.

ISSN:0010-2202    

DOI:10.1080/00102209808924162

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A systematic study of alternative single- and two-zone turbulence models proposed in the literature is performed by comparing their performance against experimental results. These models are evaluated in the context of a quasi-dimensional spark-ignition engine simulation based on the turbulent entrainment model of combustion. Crank-angle resolved cylinder pressures predicted by various models are compared to in-cylinder measurements. All models are calibrated at one operating point and their performance is assessed by keeping all empirical constants fixed at their calibration values. By performing full cycle simulations, it is shown that the two-zone models can better predict engine combustion over a wide range of speeds and loads without relying on adjustable constants or experimental initial values for each operating point.

ISSN:0010-2202    

DOI:10.1080/00102209808924163

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Flash-back of laminar methane/air flames on slit and tube burners in a wide range of burner widths and with equivalence ratios between 0.9 and 1.2 is investigated. A comparison between measured and calculated values of the critical gradients shows that the critical gradients predicted by the numerical model do not deviate more than 10% from the measured critical gradients for burners with a width/diameter ranging from 4 to 10mm and with equivalence ratios between 0.9 and 1.1. The maximum difference between the computed critical gradients of the slit and the tube burner flames is approximately 10% at a width/diameterof 4mm. The differences are not visible in the experimental data because of experimental inaccuracies. For burners sizes larger than 6 mm the differences almost vanish. An analytical model which described the decrease of the critical gradient as a function of the burner width/diameter shows that this increase is mainly caused by the curvature of the parabolic velocity profile near the burner wall.

ISSN:0010-2202    

DOI:10.1080/00102209808924164

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper presents a parallel multigrid method for computing inviscid and viscous high speed steady-state flows with reacting hydrocarbons. The governing equations for reactive flow are solved using an explicit multigrid algorithm while treating the chemical source terms in a point implicit manner. The CUSP (Convective Upwind and Split Pressure) scheme is used to provide necessary artificial dissipation without contaminating the solution. This explicit method yields excellent parallel speedups, thus enabling the calculation of reactive flows with detailed chemical kinetics including large numbers of species and reactions. Results indicate good multigrid speedups and adequate resolution of the reaction zone in inviscid and viscous two-dimensional hydrogen/air and methane/air test cases.

ISSN:0010-2202    

DOI:10.1080/00102209808924165

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An experimental study of the liftoff heights and visible flame lengths of hydrogen jet diffusion flames in still air as well as the liftoff, blowout, and blowoff characteristics of pure and diluted hydrogen flames with or without co-flowing air stream is presented. The results show that away from the forced convection limit the flame lengths for different fuel nozzle diameters can be collapsed onto a single curve if they are plotted in terms of the non-dimensional groupings. The jet diffusion flame in still air is liftoff and drop-back at an exit velocity of 535m/s and 320m/s, respectively. As the co-flowing air and pure hydrogen exit velocities are respectively increased to 7.5 ∼ 8.5 m/s and 500m/s, a very sensitive blowout region appears in the diffusion flames. Further increases of the co-flowing air velocity beyond 8.5 mlscause the flames blowoff. Under no co-flowing air conditions, the blowoff of the hydrogen diluted with air flames is dependent on the mixture exit velocities and diluent concentrations, and is independent of nozzle diameters. However, the blowout of the diluted flames is dependent on the exit velocities, diluent concentrations, and nozzle diameters.

ISSN:0010-2202    

DOI:10.1080/00102209808924166

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A stochastic model is proposed to describe the correlation between the scalar fluctuations and their dissipation and the distribution of the conditional scalar dissipation in flows characterised by ‘young’ scalar turbulence, such as the mixing layer formed between opposed jets. It predicts the scalar field from an ensemble of instantaneous scalar interfaces of specified functional form, referred to as mixinglets, randomly displaced in space, and is shown to compare favourably with experimental data from counterflows and direct numerical simulations of scalar fields characterised by short residence times. The model is initially formulated to account for molecular diffusion and turbulent convection and then extended to include all turbulent transport processes by incorporating a description for the instantaneous turbulent strain rates. The contribution of each mechanism to the evolution of the single and joint statistics is quantified individually and the ability of the model to represent conditional scalar statistics with application to combustion modelling is addressed.

ISSN:0010-2202    

DOI:10.1080/00102209808924167

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The theoretical model or metal agglomeration in solid propellants comhustion is developed. The derivation of the basic integral equation for agglomeration theory is produced. The analytical solution of the equation for monodisperse initial metal powder is obtained. The effect of different factors on the agglomeration process are investigated. The comparison with known experimental data is carried out.

ISSN:0010-2202    

DOI:10.1080/00102209808924168

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This article is a continuation of the work (Rashkovsky, 1998).The solution method of equation of metal agglomeration in solid propellants combustion theory is suggested. Itis based on statistical tests method (Monte Carlo method). Different agglomeration mechanisms have been investigated and agglomerates probability density function for different ammonium perchlorate (AP) particles spectra have been obtained, as well as dependencies ofaverage mass agglomerates diameter upon average mass diameter of AP particles. It is shown, that mass agglomerates distribution is of polymodal nature, which corresponds to knownexperimental data. Effect of different factors on agglomerates dispersity has been investigated. This paper includes analysis of different calculated schemes. Besides, the peculiarities of Monte Carlo method applying and common recommendations, necessary for making new calculation models of the metal agglomeration process in composite solid propellants combustion are considered. The effect of different process parameters on the agglomerationintensity are investigated.

ISSN:0010-2202    

DOI:10.1080/00102209808924169

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Due to the complexity of the combustion processes of airbag Inflators, neural networks are adopted for the inverse problem of specifying combustion parameters in the design of airbag inflators. Successful use of neural networks has been demonstrated in this study. During the training and verification phases of the use of neural networks, the predicted target vectors (i.e., the diameter and number of the gas-generation propellant pellets) are within 1.3% and 1.9%, respectively, of the training and testing vectors. The predicted pressure-time histories in the discharge task are also in excellent agreement with the training and testing pressure-time histories. Neural networks are also found to be able to predict well outside the training domain in this study. Based on the results from a parametric study, the values of neural network parameters for obtaining the best training quality are also summarized in this paper.

ISSN:0010-2202    

DOI:10.1080/00102209808924170

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Accurate jump relations for Chapman-Jouguet (CJ) and overdriven gaseous detonation waves are derived. The difficulty in accurately approximating the energy equation in a perfect gas two-gamma detonation jump formulation is resolved by adjusting the authentic combustion heat release in terms of linearly approximated up- and down-stream sensible enthalpies at the CJ condition where it is exactly satisfied for CJ and well approximated for overdriven waves. The basis of the success of the derived two-gamma jump relations is explained. Explicit thermodynamic jump relations across a normal detonation wave are obtained. These approximate jump relations depend on the following four parameters: γ upstream isentropic exponent (or the gamma giving pertinent upstream sound speed for defining Mj); γJ, CJ isentropic exponent (or the gamma giving pertinent sound speed for a CJ state); Mjupstream Mach number; and MJ, CJ Mach number. γJand Mjcan be obtained numerically, or experimentally with the derived jump relations. Comparisons of exact numerical and the present approximate calculation for jump conditions of CJ and overdriven detonations for methane- and hydrogen-oxygen systems show excellent agreement over a wide range of upstream Mach number, temperature, pressure, and mixture conditions.

ISSN:0010-2202    

DOI:10.1080/00102209808924171

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor