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Papers by Kevin Nordin-Bates

Research paper thumbnail of A computational study of supersonic combustion in strut injector and hypermixer flow fields

Proceedings of the Combustion Institute

Achieving sufficiently high combustion efficiency and stability in supersonic combustion is extre... more Achieving sufficiently high combustion efficiency and stability in supersonic combustion is extremely challenging and highly dependent on the fuel-injection and mixing strategies adopted. A viable approach to this is the strut injector, which by inducing flow recirculation, facilitates flame stabilization in the strut-wake. In this investigation we examine in detail the flow, mixing, self-ignition and flame stabilization mechanisms of conventional and alternating-wedge injection struts. In order to analyze these, we consider NAL’s supersonic combustor, equipped with two conventional two-stage injection struts, and an alternating-wedge injection strut, in conjunction with ONERA’s vitiation air heater. Experimental results, including spontaneous flame images, wall-pressure and Planar Laser Induced Fluorescence (PLIF) images of hydroxyl (OH) are here combined with computational results based on finite-rate chemistry Large Eddy Simulation (LES) with skeletal hydrogen-air reaction mechan...

Research paper thumbnail of Understanding Scramjet Combustion using LES of the HyShot II Combustor: Stable Combustion and Incipient Thermal Choking

51st AIAA/SAE/ASEE Joint Propulsion Conference, 2015

Research paper thumbnail of Combustion LES of a Multi-Burner Annular Aeroengine Combustor using a Skeletal Reaction Mechanism for Jet-A Air Mixtures

51st AIAA/SAE/ASEE Joint Propulsion Conference, 2015

Research paper thumbnail of Understanding Scramjet Combustion using LES of the HyShot II Combustor

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference, 2015

Research paper thumbnail of Numerical simulation and analysis of the transition to turbulence

Lecture Notes in Physics, 1997

The aim of this survey is to discuss some of the difficulties one can encounter both when solving... more The aim of this survey is to discuss some of the difficulties one can encounter both when solving Navier-Stokes equations for incompressible flows by an obstacle and analysing the approximate solutions. Far to be exhaustive, some main aspects of the numerical simulation are deliberately pointed out, in addition to the way the obstacle is taken into account and to the

Research paper thumbnail of Numerical modelling and analysis of the transition to detonation in gases

Research paper thumbnail of Developing the next-generation climate system

Research paper thumbnail of Numerical simulation of detonation structures using a thermodynamically consistent and fully conservative reactive flow model for multi-component computations

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2009

Research paper thumbnail of Well-balanced compressible cut-cell simulation of atmospheric flow

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2009

Cut-cell meshes present an attractive alternative to terrain-following coordinates for the repres... more Cut-cell meshes present an attractive alternative to terrain-following coordinates for the representation of topography within atmospheric flow simulations, particularly in regions of steep topographic gradients. In this paper, we present an explicit twodimensional method for the numerical solution on such meshes of atmospheric flow equations including gravitational sources. This method is fully conservative and allows for time steps determined by the regular grid spacing, avoiding potential stability issues due to arbitrarily small boundary cells. We believe that the scheme is unique in that it is developed within a dimensionally split framework, in which each coordinate direction in the flow is solved independently at each time step. Other notable features of the scheme are: (i) its conceptual and practical simplicity, (ii) its flexibility with regard to the one-dimensional flux approximation scheme employed, and (iii) the well-balancing of the gravitational sources allowing for stable simulation of near-hydrostatic flows. The presented method is applied to a selection of test problems including buoyant bubble rise interacting with geometry and lee-wave generation due to topography.

Research paper thumbnail of Developing the next-generation climate system models: challenges and achievements

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2009

Research paper thumbnail of An Eulerian algorithm for coupled simulations of elastoplastic-solids and condensed-phase explosives

Journal of Computational Physics, 2013

The performance of non-ideal condensed-phase explosives depends on the nature of the confiner mat... more The performance of non-ideal condensed-phase explosives depends on the nature of the confiner material as well as the charge itself, so the accurate modelling of this confiner and its interaction with the explosive allows for improved performance predictions. Traditionally, numerical methods for solving such multi-material problems have used Lagrangian or mixed Eulerian-Lagrangian approaches, but recent advances in numerical methods for coupling CFD (Computational Fluid Dynamics) and CMD (Computational Material Dynamics) algorithms has made such coupled simulations possible in the Eulerian frame of reference. However, to date, the explosive material representation within these simulations has been restricted to the single-phase Euler equations. In the present study we couple a multiphase chemically-active model for condensed-phase explosives to an elastic-plastic model for inert confiner materials. In the presented algorithm, the ghost-fluid method is employed to represent the evolving material interfaces as discontinuities on discrete space. The coupling between the materials at these interfaces is achieved by means of a new approximate mixed Riemann solver, developed as part of this research. In addition we present a mixed Riemann solver for a simpler transport model, which ignores compaction effects at the interface. The robustness and accuracy of the developed solvers is demonstrated by comparisons against results from the original ghost-fluid method and exact solutions of model Riemann problems. To allow for more realistic material behaviour, the mixed Riemann solvers are subsequently extended to handle the shock Mie-Grüneisen equation of state, and an iterative procedure is suggested to increase accuracy as required. These mixed Riemann solvers demonstrate their suitability for explosive-solid interactions in two test cases of multi-phase detonations confined by an elastic-plastic solid.

Research paper thumbnail of The growth of fractal dimension of an interface evolution from the interaction of a shock wave with a rectangular block of SF6

Communications in Nonlinear Science and Numerical Simulation, 2011

The interface between air and a rectangular block of sulphur hexafluoride (SF6), impulsively acce... more The interface between air and a rectangular block of sulphur hexafluoride (SF6), impulsively accelerated by the passage of a planar shock wave, undergoes Richtmyer-Meshkov instability and the flow becomes turbulent. The evolution of the interface was previously simulated using a multi-component model based on a thermodynamically consistent and fully conservative formulation and results were validated against available experimental data (Bates et al. Richtmyer-Meshkov instability induced by the interaction of a shock wave with a rectangular block of SF6, Phys Fluids, 2007; 19:036101). In this study, the CFD results are analyzed using the fractal theory approach and the evolution of fractal dimension of the interface during the transition of the flow into fully developed turbulence is measured using the standard box-counting method. It is shown that as the Richtmyer-Meshkov instability on the interface develops and the flow becomes turbulent, the fractal dimension of the interface increases asymptotically toward a value close to 1.39, which agrees well to those measured for classical shear and fully developed turbulences.

Research paper thumbnail of Nonlinear dynamics and chaos analysis of one-dimensional pulsating detonations

Combustion Theory and Modelling, 2005

To understand the nonlinear dynamical behaviour of a one-dimensional pulsating detonation, result... more To understand the nonlinear dynamical behaviour of a one-dimensional pulsating detonation, results obtained from numerical simulations of the Euler equations with simple one-step Arrhenius kinetics are analysed using basic nonlinear dynamics and chaos theory. To illustrate the transition pattern from a simple harmonic limit-cycle to a more complex irregular oscillation, a bifurcation diagram is constructed from the computational results. Evidence suggests that the route to higher instability modes may follow closely the ...

Research paper thumbnail of Compressible Multi-Gas Flow Simulation

Research paper thumbnail of Richtmyer-Meshkov instability induced by the interaction of a shock wave with a rectangular block of SF

Physics of Fluids, Mar 1, 2007

In this article the interaction of a shock wave with a rectangular block of sulphur hexafluoride,... more In this article the interaction of a shock wave with a rectangular block of sulphur hexafluoride, occupying part of the test section of a shock tube, is studied by experimental and numerical means. The difference between the ratios of the specific heats of the two gases (air and) gives rise to numerical problems (generation of spurious waves at their interface). This necessitated the development of a multifluid algorithm (augmented Navier-Stokes formulation). The governing equations are based on a thermodynamically ...

Research paper thumbnail of A computational study of supersonic combustion in strut injector and hypermixer flow fields

Proceedings of the Combustion Institute

Achieving sufficiently high combustion efficiency and stability in supersonic combustion is extre... more Achieving sufficiently high combustion efficiency and stability in supersonic combustion is extremely challenging and highly dependent on the fuel-injection and mixing strategies adopted. A viable approach to this is the strut injector, which by inducing flow recirculation, facilitates flame stabilization in the strut-wake. In this investigation we examine in detail the flow, mixing, self-ignition and flame stabilization mechanisms of conventional and alternating-wedge injection struts. In order to analyze these, we consider NAL’s supersonic combustor, equipped with two conventional two-stage injection struts, and an alternating-wedge injection strut, in conjunction with ONERA’s vitiation air heater. Experimental results, including spontaneous flame images, wall-pressure and Planar Laser Induced Fluorescence (PLIF) images of hydroxyl (OH) are here combined with computational results based on finite-rate chemistry Large Eddy Simulation (LES) with skeletal hydrogen-air reaction mechan...

Research paper thumbnail of Understanding Scramjet Combustion using LES of the HyShot II Combustor: Stable Combustion and Incipient Thermal Choking

51st AIAA/SAE/ASEE Joint Propulsion Conference, 2015

Research paper thumbnail of Combustion LES of a Multi-Burner Annular Aeroengine Combustor using a Skeletal Reaction Mechanism for Jet-A Air Mixtures

51st AIAA/SAE/ASEE Joint Propulsion Conference, 2015

Research paper thumbnail of Understanding Scramjet Combustion using LES of the HyShot II Combustor

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference, 2015

Research paper thumbnail of Numerical simulation and analysis of the transition to turbulence

Lecture Notes in Physics, 1997

The aim of this survey is to discuss some of the difficulties one can encounter both when solving... more The aim of this survey is to discuss some of the difficulties one can encounter both when solving Navier-Stokes equations for incompressible flows by an obstacle and analysing the approximate solutions. Far to be exhaustive, some main aspects of the numerical simulation are deliberately pointed out, in addition to the way the obstacle is taken into account and to the

Research paper thumbnail of Numerical modelling and analysis of the transition to detonation in gases

Research paper thumbnail of Developing the next-generation climate system

Research paper thumbnail of Numerical simulation of detonation structures using a thermodynamically consistent and fully conservative reactive flow model for multi-component computations

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2009

Research paper thumbnail of Well-balanced compressible cut-cell simulation of atmospheric flow

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2009

Cut-cell meshes present an attractive alternative to terrain-following coordinates for the repres... more Cut-cell meshes present an attractive alternative to terrain-following coordinates for the representation of topography within atmospheric flow simulations, particularly in regions of steep topographic gradients. In this paper, we present an explicit twodimensional method for the numerical solution on such meshes of atmospheric flow equations including gravitational sources. This method is fully conservative and allows for time steps determined by the regular grid spacing, avoiding potential stability issues due to arbitrarily small boundary cells. We believe that the scheme is unique in that it is developed within a dimensionally split framework, in which each coordinate direction in the flow is solved independently at each time step. Other notable features of the scheme are: (i) its conceptual and practical simplicity, (ii) its flexibility with regard to the one-dimensional flux approximation scheme employed, and (iii) the well-balancing of the gravitational sources allowing for stable simulation of near-hydrostatic flows. The presented method is applied to a selection of test problems including buoyant bubble rise interacting with geometry and lee-wave generation due to topography.

Research paper thumbnail of Developing the next-generation climate system models: challenges and achievements

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2009

Research paper thumbnail of An Eulerian algorithm for coupled simulations of elastoplastic-solids and condensed-phase explosives

Journal of Computational Physics, 2013

The performance of non-ideal condensed-phase explosives depends on the nature of the confiner mat... more The performance of non-ideal condensed-phase explosives depends on the nature of the confiner material as well as the charge itself, so the accurate modelling of this confiner and its interaction with the explosive allows for improved performance predictions. Traditionally, numerical methods for solving such multi-material problems have used Lagrangian or mixed Eulerian-Lagrangian approaches, but recent advances in numerical methods for coupling CFD (Computational Fluid Dynamics) and CMD (Computational Material Dynamics) algorithms has made such coupled simulations possible in the Eulerian frame of reference. However, to date, the explosive material representation within these simulations has been restricted to the single-phase Euler equations. In the present study we couple a multiphase chemically-active model for condensed-phase explosives to an elastic-plastic model for inert confiner materials. In the presented algorithm, the ghost-fluid method is employed to represent the evolving material interfaces as discontinuities on discrete space. The coupling between the materials at these interfaces is achieved by means of a new approximate mixed Riemann solver, developed as part of this research. In addition we present a mixed Riemann solver for a simpler transport model, which ignores compaction effects at the interface. The robustness and accuracy of the developed solvers is demonstrated by comparisons against results from the original ghost-fluid method and exact solutions of model Riemann problems. To allow for more realistic material behaviour, the mixed Riemann solvers are subsequently extended to handle the shock Mie-Grüneisen equation of state, and an iterative procedure is suggested to increase accuracy as required. These mixed Riemann solvers demonstrate their suitability for explosive-solid interactions in two test cases of multi-phase detonations confined by an elastic-plastic solid.

Research paper thumbnail of The growth of fractal dimension of an interface evolution from the interaction of a shock wave with a rectangular block of SF6

Communications in Nonlinear Science and Numerical Simulation, 2011

The interface between air and a rectangular block of sulphur hexafluoride (SF6), impulsively acce... more The interface between air and a rectangular block of sulphur hexafluoride (SF6), impulsively accelerated by the passage of a planar shock wave, undergoes Richtmyer-Meshkov instability and the flow becomes turbulent. The evolution of the interface was previously simulated using a multi-component model based on a thermodynamically consistent and fully conservative formulation and results were validated against available experimental data (Bates et al. Richtmyer-Meshkov instability induced by the interaction of a shock wave with a rectangular block of SF6, Phys Fluids, 2007; 19:036101). In this study, the CFD results are analyzed using the fractal theory approach and the evolution of fractal dimension of the interface during the transition of the flow into fully developed turbulence is measured using the standard box-counting method. It is shown that as the Richtmyer-Meshkov instability on the interface develops and the flow becomes turbulent, the fractal dimension of the interface increases asymptotically toward a value close to 1.39, which agrees well to those measured for classical shear and fully developed turbulences.

Research paper thumbnail of Nonlinear dynamics and chaos analysis of one-dimensional pulsating detonations

Combustion Theory and Modelling, 2005

To understand the nonlinear dynamical behaviour of a one-dimensional pulsating detonation, result... more To understand the nonlinear dynamical behaviour of a one-dimensional pulsating detonation, results obtained from numerical simulations of the Euler equations with simple one-step Arrhenius kinetics are analysed using basic nonlinear dynamics and chaos theory. To illustrate the transition pattern from a simple harmonic limit-cycle to a more complex irregular oscillation, a bifurcation diagram is constructed from the computational results. Evidence suggests that the route to higher instability modes may follow closely the ...

Research paper thumbnail of Compressible Multi-Gas Flow Simulation

Research paper thumbnail of Richtmyer-Meshkov instability induced by the interaction of a shock wave with a rectangular block of SF

Physics of Fluids, Mar 1, 2007

In this article the interaction of a shock wave with a rectangular block of sulphur hexafluoride,... more In this article the interaction of a shock wave with a rectangular block of sulphur hexafluoride, occupying part of the test section of a shock tube, is studied by experimental and numerical means. The difference between the ratios of the specific heats of the two gases (air and) gives rise to numerical problems (generation of spurious waves at their interface). This necessitated the development of a multifluid algorithm (augmented Navier-Stokes formulation). The governing equations are based on a thermodynamically ...