Large Eddy Simulation of Turbulent Supersonic Combustion and Characteristics of Supersonic Flames PDF Download

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 470

View

Book Description

Author: Mingbo Sun
Publisher: Springer Nature
ISBN: 9811535957
Category : Technology & Engineering
Languages : en
Pages : 380

View

Book Description
This book describes the unsteady phenomena needed to understand supersonic combustion. Following an initial chapter that introduces readers to the basic concepts in and classical studies on unsteady supersonic combustion, the book highlights recent studies on unsteady phenomena, which offer insights on e.g. interactions between acoustic waves and flames, flow dominating instability, ignition instability, flame flashback, and near-blowout-limit combustion. In turn, the book discusses in detail the fundamental mechanisms of these phenomena, and puts forward practical suggestions for future scramjet design.

Author: Peter Cocks
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
This work evaluates the capabilities of the RANS and LES techniques for the simulation of high speed reacting flows. These methods are used to gain further insight into the physics encountered and regimes present in supersonic combustion. The target application of this research is the scramjet engine, a propulsion system of great promise for efficient hypersonic flight. In order to conduct this work a new highly parallelised code, PULSAR, is developed. PULSAR is capable of simulating complex chemistry combustion in highly compressible flows, based on a second order upwind method to provide a monotonic solution in the presence of high gradient physics. Through the simulation of a non-reacting supersonic coaxial helium jet the RANS method is shown to be sensitive to constants involved in the modelling process. The LES technique is more computationally demanding but is shown to be much less sensitive to these model parameters. Nevertheless, LES results are shown to be sensitive to the nature of turbulence at the inflow; however this information can be experimentally obtained. The SCHOLAR test case is used to validate the reacting aspects of PULSAR. Comparing RANS results from laminar chemistry and assumed PDF combustion model simulations, the influence of turbulence-chemistry interactions in supersonic combustion is shown to be small. In the presence of reactions, the RANS results are sensitive to inflow turbulence, due to its influence on mixing. From complex chemistry simulations the combustion behaviour is evaluated to sit between the flamelet and distributed reaction regimes. LES results allow an evaluation of the physics involved, with a pair of coherent vortices identified as the dominant influence on mixing for the oblique wall fuel injection method. It is shown that inflow turbulence has a significant impact on the behaviour of these vortices and hence it is vital for turbulence intensities and length scales to be measured by experimentalists, in order for accurate simulations to be possible.

Author: Yuri Paixao De Almeida
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description

Author: Tarek Echekki
Publisher: Springer Science & Business Media
ISBN: 9400704127
Category : Technology & Engineering
Languages : en
Pages : 496

View

Book Description
Turbulent combustion sits at the interface of two important nonlinear, multiscale phenomena: chemistry and turbulence. Its study is extremely timely in view of the need to develop new combustion technologies in order to address challenges associated with climate change, energy source uncertainty, and air pollution. Despite the fact that modeling of turbulent combustion is a subject that has been researched for a number of years, its complexity implies that key issues are still eluding, and a theoretical description that is accurate enough to make turbulent combustion models rigorous and quantitative for industrial use is still lacking. In this book, prominent experts review most of the available approaches in modeling turbulent combustion, with particular focus on the exploding increase in computational resources that has allowed the simulation of increasingly detailed phenomena. The relevant algorithms are presented, the theoretical methods are explained, and various application examples are given. The book is intended for a relatively broad audience, including seasoned researchers and graduate students in engineering, applied mathematics and computational science, engine designers and computational fluid dynamics (CFD) practitioners, scientists at funding agencies, and anyone wishing to understand the state-of-the-art and the future directions of this scientifically challenging and practically important field.

Author: Doyle Knight
Publisher:
ISBN:
Category :
Languages : en
Pages : 12

View

Book Description
A Large Eddy Simulation (LES) methodology has been developed for supersonic turbulent flows with strong shock boundary layer interaction. Results are presented for an expansion-compression corner at Mach 3 and compared with experimental data.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

View

Book Description
The interaction of a shock wave with a turbulent boundary layer is a central problem in supersonic inlet flows. This work uses numerical and analytical techniques to study shock/turbulence interaction in order to identify and explain factors important in shock/boundary layer interaction. Direct numerical simulation of a normal shock wave with an isotropic turbulent field of vorticity and entropy fluctuations showed that negative upstream correlation between the vorticity and entropy fluctuations enhances the turbulence across the shock. Positive upstream correlation has a suppressing effect. A new numerical method providing excellent high wavenumber resolution while reducing the computational cost was developed. A model with no adjustable constants was developed to study the vortex breakdown resulting from the interaction of canard or forbody vortices with the shock waves in a supersonic inlet flow. Very good agreement with both experiment and computation was obtained. A numerical method to compute shock/turbulence interaction using a conservative form of the Large Eddy Simulation (LES) equations has been developed and validated. LES of the interaction of isotropic turbulence with a normal shock was performed and comparisons with direct numerical simulation (DNS) results were favorable. A new Fortran 90 code has been developed for the computation of shock/turbulence interaction. The code is an improved version of codes used previously in shock/turbulence interaction simulations.

Author: Rogério Goncalves Dos santos
Publisher:
ISBN:
Category :
Languages : en
Pages : 125

View

Book Description
The combustion is one of the principal ways to produced energy used nowadays, it is also a complex phenomenon, where the turbulent flow, chemical reactions, different phases and different heat transfer phenomena can interact. Better understanding of these interactions is essential to improve the actual combustion system and to developed the new ones. The goal of this thesis is to study the interaction of the turbulent combustion with the thermal radiation by the use of three-dimensional numerical simulation. For that, using a computational tool named CORBA, a code for the combustion Large Eddy Simulation (LES) was coupled with a radiative heat transfer code. This technique allows the exchange of information between the two codes without big changes in their structure, then it is possible to take advantages of the different characteristic time from each phenomenon in a high performance parallel computational environment. In a first time, two-dimensional simulation of a turbulent propane/air premixed flame stabilized downstream a triangular flame holder has been realised. After the changing of the twodimensional radiation code for another three-dimensional one, the same configuration was simulated in 3D. A mesh with more than 4.7 millions cells for the combustion code (AVBP) and more than 3.3 millions cells for the radiation code (DOMASIUM) are used. Results show a changing in the temperature and species fields, as well as in the flame dynamics when the thermal radiation was taken into account, with a minor intensity in the three-dimensional simulations. This method, also, shows that it is possible to perform 3D complex simulations in a industrial acceptable time.

Author: Jason W. Norris
Publisher:
ISBN:
Category :
Languages : en
Pages : 202

View

Book Description

Author: Bonnie J. McBride
Publisher:
ISBN:
Category : Chemical equilibrium
Languages : en
Pages : 100

View

Book Description