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Computation have been made of the three‐dimensional flow field development, chemical reaction and combustion processes in a typical afterburner system under both isothermal and reacting flow conditions. The calculations are based upon a numerical solution of the time‐averaged transport equations for mass, momentum, turbulence kinetic energy, dissipation rate, enthalpy and species concentrations using a finite‐volume formulation. The physical models include the k—ε turbulence model, the eddy break‐up model, a two‐step reaction model, a droplet vaporization and combustion model and six‐flux radiation model. The mean flow structures are presented in important longitudinal and cross‐sectional planes which show certain striking similarities and contrasting differences for isothermal and reacting flows. The flame stabilizer flow is shown to be dominated by a complex combination of recirculation and vortex patterns. Combustion alters convergence and mixing flow patterns downstream of the flame stabilizer, thus influencing the selection of the fuel injection system. The predicted reacting flow parameters identify a number of design parameters such as fuel injector location, high degree reaction zone, nozzle opening area and the corresponding fuel flow rate.

A mathematical model has been developed to study turbulent, confined, swirling flows under reacting non‐premixed conditions. The model solves the conservation equations of mass, momentum, energy, species, and two additional equations for the turbulent kinetic energy and the turbulent length scale. Combustion has been modelled by means of a one‐step overall chemical reaction. The numerical predictions based on the eddy‐break‐up model of turbulent combustion show a recirculation zone in the form of a one‐celled toroidal vortex at the combustor centreline. High levels of turbulence characterize the recirculation zone, whose diameter and velocity first decrease and then increase as the magnitude of the outer swirl number is first decreased from counter‐swirl to zero and then increased to co‐swirl flow conditions. Counter‐swirl produces steeper velocity gradients at the inter‐jet shear layer, promotes faster mixing and yields better combustion efficiency than co‐swirl. The numerical results are compared with those obtained under non‐reacting conditions in order to assess the influence of the heat release on the size of the recirculation zone.

A mathematical model has been developed to study incompressible, isothermal, turbulent, confined, swirling flows. The model solves the conservation equations of mass, momentum, and two additional equations for the turbulent kinetic energy and the rate of dissipation of turbulent kinetic energy. The numerical predictions show a recirculation zone in the form of a one‐celled toroidal vortex at the combustor centreline. High levels of turbulence characterize the recirculation zone. The length, diameter and maximum velocity of the recirculation zone first decrease and then increase as the magnitude of the outer swirl number is first decreased from counter‐swirl to zero and then increased to co‐swirl flow conditions. Counter‐swirl produces steeper velocity gradients at the inter‐jet shear layer and promotes faster mixing than co‐swirl. The numerical results also indicate that the mass of the recirculation zone first decreases and then increases as the outer swirl number is first decreased from counter‐swirl to zero and then increased to co‐swirl conditions. The diameter, maximum velocity and mass of the recirculation zone are monotonically increasing functions of the inner jet swirl number. The recirculation zone length, diameter and mass are almost independent of the Reynolds number and outer‐to‐inner jet axial velocity ratio.

The purpose of this paper is to perform the simulation to explore the gap flow field under a hypersonic air flow. Thermal protection systems of hypersonic vehicles generally consist of thermal insulation tiles, and gaps between these tiles probably cause a severe local aerodynamic thermal effect.

The discretizations of convection flux term and temporal term in the governing equation with chemical equilibrium, respectively, take AUSM+-up flux-vector splitting scheme and the implicit lower-upper symmetric Gauss–Seidel method. Based on these, the flow field in a deep gap is simulated by means of the computer codes that the authors have written.

The numerical results show that the heat flux distribution in a gap has a good agreement with experimental results. Importantly, the distribution of heat flux is “U” shaped and the maximum of the heat flux occurs at the windward corner of a gap.

To explore the gap flow field under a hypersonic air flow, which is a chemically reacting, all speed and viscous flow, a novel model with an equivalent ratio of specific heats is presented. The investigation in this paper has a guide for the design of the thermal protection system in hypersonic vehicles.

Solutions of the twin plane jets HF chemical laser flow based on a turbulent kinetic theory, due to a modified Green’s function method, are presented. The calculated results of probability density function (PDF) of various chemical species in velocity space, and mass fraction concentration distributions of various reactants and products in the flow field, are revealed and discussed in this analysis. The transport phenomena of different pumping rate, collisional deactivation rate, and radiative deactivation rate in the interaction between the twin plane jets HF chemical laser show that the properties of species mass fraction concentrations, collisional reaction rate, and radiative incident intensity are the dominant factors. The present study provides the fundamentals for theoretical understanding of twin plane jets HF chemical laser and further application to multiple‐jet HF chemical laser analysis.

The purpose of this paper is to optimize the performance of an incinerator plant in terms of NO emissions and temperature of particles 2 s after the last air injection, which must be above 850°C as established from the Directive 2000/76/EC of the European Parliament and of the Council – December 4, 2000 on dioxins formation in waste incineration plants.

Investigation is made by coupling proper models developed within three commercial software environments: FLUENT, to reproduce the thermodynamic field inside the combustion chamber of the incinerator plant taken into account, MATLAB, to evaluate the position and temperatures of the particles 2 s after the last air injection, MODEFRONTIER, to change both the secondary air mass flow rate and the equivalent heat transfer coefficient of the refractory walls to fulfill the conflicting objectives of reducing the NO formation and increasing the mean gases temperature as required by the Directive.

The investigations suggest that it is possible to create the conditions allowing the reduction of NO emissions and the fulfilment of the European limits. In particular, the obtained results suggest that increasing the overall mass flow rate of the secondary air and using a different refractory material on the walls, the environmental performance of the incinerator plant can be improved.

Many other parameters could be optimized and, at the same time, more detailed models could be used for the Computational Fluid Dynamics simulations. Moreover, also the energy generated at the plant would need a better investigation in order to understand if optimal conditions can be really achieved.

The work covers new aspects of Waste-to-Energy (WtE) systems, since it deals with an optimization study of plant design and operating parameters. This kind of investigation allows not only to improve already existing technologies for WtE systems, but also to develop new ones.

In various kinds of materials processes, heat and mass transfer control in nuclear phenomena, constructing buildings, turbines and electronic circuits, etc., there are numerous problems that cannot be enlightened by uniform wall temperature. To explore such physical phenomena researchers incorporate non-uniform or ramped temperature conditions at the boundary, the purpose of this paper is to achieve the closed-form solution of a time-dependent magnetohydrodynamic (MHD) boundary layer flow with heat and mass transfer of an electrically conducting non-Newtonian Casson fluid toward an infinite vertical plate subject to the ramped temperature and concentration (RTC). The consequences of chemical reaction in the mass equation and thermal radiation in the energy equation are encompassed in this analysis. The flow regime manifests with pertinent physical impacts of the magnetic field, thermal radiation, chemical reaction and heat generation/absorption. A first-order chemical reaction that is proportional to the concentration itself directly is assumed. The Rosseland approximation is adopted to describe the radiative heat flux in the energy equation.

The problem is formulated in terms of partial differential equations with the appropriate physical initial and boundary conditions. To make the governing equations dimensionless, some suitable non-dimensional variables are introduced. The resulting non-dimensional equations are solved analytically by applying the Laplace transform method. The mathematical expressions for skin friction, Nusselt number and Sherwood number are calculated and expressed in closed form. Impacts of various associated physical parameters on the pertinent flow quantities, namely, velocity, temperature and concentration profiles, skin friction, Nusselt number and Sherwood number, are demonstrated and analyzed via graphs and tables.

Graphical analysis reveals that the boundary layer flow and heat and mass transfer attributes are significantly varied for the embedded physical parameters in the case of constant temperature and concentration (CTC) as compared to RTC. It is worthy to note that the fluid velocity is high with CTC and lower for RTC. Also, the fluid velocity declines with the augmentation of the magnetic parameter. Moreover, growth in thermal radiation leads to a declination in the temperature profile.

The proposed model has relevance in numerous engineering and technical procedures including industries related to polymers, area of chemical productions, nuclear energy, electronics and aerodynamics. Encouraged by such applications, the present work is undertaken.

Literature review unveils that sundry studies have been carried out in the presence of uniform wall temperature. Few studies have been conducted by considering non-uniform or ramped wall temperature and concentration. The authors are focused on an analytical investigation of an unsteady MHD boundary layer flow with heat and mass transfer of non-Newtonian Casson fluid past a moving plate subject to the RTC at the plate. Based on the authors’ knowledge, the present study has, so far, not appeared in scientific communications. Obtained analytical solutions are verified by considering particular cases of the published works.

A simple convection algorithm for simulation of time‐dependent supersonic and hypersonic flows of a perfect but viscous gas is described. The algorithm is based on conservation and convection of mass, momentum and energy in a grid of rectangular cells. Examples are given for starting flow in a shock‐tube and oblique shocks generated by a wedge, at Mach numbers up to 30.4. Good comparisons are achieved with well‐known perfect gas flows.

The purpose of this paper is to focus on MHD unsteady flow of Carreau fluid over a variable thickness melting surface in the presence of chemical reaction and non-uniform heat sink/source.

The flow governing partial differential equations are transformed into ordinary ones with the help of similarity transformations. The set of ODEs are solved by a shooting technique together with the R.K.–Fehlberg method. Further, the graphs are depicted to scrutinize the velocity, concentration and temperature fields of the Carreau fluid flow. The numerical values of friction factor, heat and mass transfer rates are tabulated.

The results are presented for both Newtonian and non-Newtonian fluid flow cases. The authors conclude that the nature of three typical fields and the physical quantities are alike in both cases. An increase in melting parameter slows down the velocity field and enhances the temperature and concentration fields. But an opposite outcome is noticed with thermal relaxation parameter. Also the elevating values of thermal relaxation parameter/ wall thickness parameter/Prandtl number inflate the mass and heat transfer rates.

This is a new research article in the field of heat and mass transfer in fluid flows. Cattaneo–Christov heat flux model is used. The surface of the flow is assumed to be melting.

The purpose of this paper is to scrutinize the heat and mass transfer attributes of three-dimensional bio convective flow of nanofluid across a slendering surface with slip effects. The analysis is carried out subject to irregular heat sink/source, thermophoresis and Brownian motion of nanoparticles.

At first, proper transmutations are pondered to metamorphose the basic flow equations as ODEs. The solution of these ODEs is procured by the consecutive application of Shooting and Runge-Kutta fourth order numerical procedures.

The usual flow fields along with density of motile microorganisms for sundry physical parameters are divulged via plots and scrutinized. Further, the authors analyzed the impact of same parameters on skin friction, heat and mass transfer coefficients and presented in tables. It is discovered that the variable heat sink/source parameters play a decisive role in nature of the heat and mass transfer rates. The density of motile microorganisms will improve if we add Al-Cu alloy particles in regular fluids instead of Al particles solely. A change in thermophoresis and Brownian motion parameters dominates heat and mass transfer performance.

To the best of the knowledge, no author made an attempt to investigate the flow of nanofluids over a variable thickness surface with bio-convection, Brownian motion and slip effects.