Editor-in-Chief: Dr. R. I Sujith
published quarterly ISSN 1756-8277 2012 journal prices/format options
2012 is volume 4
Combustion dynamics is a growing area that has received fresh emphasis due to advances in energy efficient and low emission combustion systems for ground-based as well as aerospace power plants. The occurrence of thermo-acoustic instabilities, popularly known as combustion instabilities, has been a plaguing problem in the development of combustors for rockets, jet engines, power generating gas turbines and process or domestic heaters. Significant advances in understanding and controlling combustion instability is critical for pushing the operating envelope of the existing installations, and in avoiding delays and cost overruns in development programmes. Understanding and reducing combustion noise has been a priority in recent times, in an effort towards reducing noise pollution from power plants. Low emission combustors are prone to combustion instabilities and flame blow out. Rapid developments in pulse detonation engines are fuelling research in the area of detonation. Pulse combustors are used to improve the efficiency of energy intensive processes, by taking advantage of the increased mass, momentum and energy transport in the presence of high intensity acoustic fields. Liquid fuels are often used in combustors; therefore, combustion dynamics is often closely related to droplet and spray dynamics and atomization.
The topic is, of course, not new. However, it has been the case that published research on combustion dynamics has been scattered among numerous journals and conference proceedings, not all of them readily accessible. It is in order to draw this work together in one publication, and to reflect the growing importance of the subject, that the International Journal of Spray and Combustion Dynamics is being established.
The International Journal of Spray and Combustion Dynamics will publish developments covering fundamental and applied research in combustion and spray dynamics. Fundamental topics include advances in understanding unsteady combustion, combustion instability and noise, flame-acoustic interaction and its active and passive control, duct acoustics, blow out and flash back, deflagration and detonations, droplet and spray dynamics and combustion, atomisation, droplet and spray-acoustic interactions,. Applied topics include all aspects of combustion instabilities in solid and liquid rocket motors and gas turbine combustors, combustion noise, pulse detonation engines, active control of combustion instabilities and active control of sprays. As well as original contributions, state of the art reviews and surveys will be published.
Subtopics include, among others, experimental diagnostics of combustion dynamics, computational combustion including RANS and LES for the study of combustion dynamics, unsteady fluid mechanics, mixing, system identification and low order modelling of dynamic phenomena, role of coherent structures in combustion dynamics, flame response measurements and calculation, non-normality and nonlinearity in flame acoustic interaction, analytical acoustics, liquid sheet break-up and stability, active control of sprays, experimental diagnostics of sprays, modelling of spray break-up phenomena, two phase flow modelling and spray and droplet combustion.
Modeling and Identification of Thermoacoustic Instabilities at Various
Operating ConditionsAndré S.P. Niederberger1, Bruno
B.H. Schuermans2, and Lino Guzzella1
1Measurement and Control Laboratory, ETH Zurich, Switzerland
2ALSTOM (Switzerland) Ltd.
Abstract: This paper describes the identification and modeling of a test rig designed to study thermoacoustic instabilities. Various operating conditions with different flame structures are identified. Physics-based models are used in a network model in order to advance the understanding of the phenomena involved. The parameters identified of the flame correlate well with the observed flame shapes. The transfer function from a loudspeaker input to a pressure reading is assembled and compared to measurements. Reflection coefficients are introduced to study the amplifying frequency ranges of the flame, which correspond to the highest peaks in the pressure spectrum.
Simulation of Axial Combustion Instability Development and Suppression
in Solid Rocket Motors
David R. Greatrix
Department of Aerospace Engineering, Ryerson University, 150 Victoria Street, Toronto, Ontario, Canada M5B 2K3
Abstract: In the design of solid-propellant rocket motors, the ability to understand and predict the expected behaviour of a given motor under unsteady conditions is important. Research towards predicting, quantifying, and ultimately suppressing undesirable strong transient axial combustion instability symptoms necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. An updated numerical model incorporating recent developments in predicting negative and positive erosive burning, and transient, frequency-dependent combustion response, in conjunction with pressure-dependent and acceleration-dependent burning, is applied to the investigation of instability-related behaviour in a small cylindrical-grain motor. Pertinent key factors, like the initial pressure disturbance magnitude and the propellants net surface heat release, are evaluated with respect to their influence on the production of instability symptoms. Two traditional suppression techniques, axial transitions in grain geometry and inert particle loading, are in turn evaluated with respect to suppressing these axial instability symptoms.
Direct Comparison of Particle-Tracking and Sectional Approaches for Shock
Douglas A Schwer, K Kailasanath
Center for Reactive Flow and Dynamical Systems, Code 6410, Naval Research Laboratory, Washington, DC 20375
Abstract: Dispersed-phase flows are important for a wide variety of problems, and several numerical approaches for the solution of dispersed-phase flows have been proposed and implemented in the past. The present research implements two popular approaches to dispersed-phase flows: the Lagrangian particle-tracking approach and the Eulerian sectional approach. A direct comparison between the two methods is made for a range of shock driven seeded flow-fields. First, different drag models are investigated using the particle-tracking method for a range of conditions, and then direct comparisons between the two methods are made for shock speed attenuation and shock-wave profiles. In addition, resolution requirements are investigated to determine the number of sections and the number of particles required to obtain good agreement between the methods. Then, two-dimensional simulations are done to investigate the effect of each method on more complicated flow-fields. Results showed both methods can be used to obtain very similar results, although each method has benefits and drawbacks. The glass particles were then replaced with water droplets, and the effect of vaporization and droplet breakup were investigated. Although vaporization was well represented with the sectional approach, different droplet breakup models had to be implemented for the different approaches, with some significant differences in the resultant droplet distributions. The reason for this is that breakup models require a droplet deformation time before breaking up, and thus a droplet history. This droplet history is difficult to implement in sectional approaches (and Eulerian methods in general), and so the breakup model must be changed. Similar profiles could be reproduced with the sectional method, but significant differences persisted. The results did show, however, that the Eulerian sectional approach is a viable method for computing complex, multi-dimensional flow-fields and can provide significant numerical advantages when compared with Lagrangian particle-tracking methods, especially in flooded environments such as examined here.
Testing Premixed Turbulent Combustion Models by Studying Flame Dynamics
ANDREI N. LIPATNIKOV
Department of Applied Mechanics, Chalmers University of Technology, Göteborg, 412 96, Sweden
Abstract: First, the following universal feature of premixed turbulent flame dynamics is highlighted: During an early stage of flame development, the burning velocity grows much faster than the mean flame brush thickness, because the two processes are controlled by the small-scale and large-scale turbulent eddies, respectively. Second, this feature of developing flames is exploited in order to test a number of different models of premixed turbulent combustion by theoretically and numerically studying an interaction of an initially laminar, planar, one-dimensional flame with a statistically stationary, planar, one-dimensional, and spatially uniform turbulent flow not affected by combustion. To test as many models as possible in a simple and unified manner, various combustion models are divided into three generalized groups: (i) algebraic models, which invoke an algebraic expression for the mean rate of product creation, (ii) gradient models, which involve a gradient-type source term in a balance equation for the mean combustion progress variable, and (iii) two-equation models, which deal not only with a balance equation for the mean combustion progress variable but also with either a balance equation for the flame surface density or a balance equation for the mean scalar dissipation rate. Analytical and numerical results reported in the paper indicate that solely the gradient models are able to yield substantially different growth rates of the turbulent burning velocity and the mean flame brush thickness.
About the zero Mach number assumption in the calculation of thermoacoustic
F. NICOUD1 and K. WIECZOREK1,2
1University Montpellier II - I3M CNRS UMR 5149, Place Eugène Bataillon. 34095 Montpellier cedex 5 - France.
2CERFACS - 42, Av. Gaspard Coriolis, 31057 Toulouse cedex 1 - France.
Abstract: This paper presents an analytical/numerical study of the effects of the mean flow on thermo-acoustic instabilities. Simple quasi-1D configurations such as a 1D premixed flame in a duct connected to a nozzle are considered in order to investigate to what extent the frequency of oscillation and growth rate are modified when the Mach number is not zero. It is demonstrated that the zero Mach number assumption for the mean flow can lead to significant errors, especially when the mean flow is not isentropic, a condition which is always met in combustion applications. The analysis confirms that terms involving the mean velocity may contribute to the disturbance energy equation as much as the the ame forcing ('Rayleigh') term. Besides, the net eect of the non zero Mach number terms on the stability of the modes strongly depends on both the boundary conditions and the flame response. For moderate Mach number values of order 0:05, the errors made by assuming that the mean flow is at rest are large enough to change the stability of the frequencies of interest in an academic combustor.
Dr. R. I Sujith
Professor, Departmentof Aerospace Engineering, IIT Madras, Chennai 600036, India
John Abraham (Purdue)
Alain Berlemont, France (Coria)
M. J. Brear, Australia (U Melbourne)
H.S. Dou, Singapore (National University of Singapore)
Prof. Derek Dunn-Rankin (University of California)
Osamu Fujita, Japan (Hokkaido University)
B. Greenberg, Israel (Technion, Israel Institute of Technology)
G. Gogos, USA (University of Nebraska - Lincoln)
A. K. Gupta, USA (U. Maryland)
Y. Hardalupas, UK (Imperial College)
M.P. Juniper, UK (Cambridge)
K. Kailasanath, USA (Naval Research Lab)
J. B. W. Kok, The Netherlands (U. Twente)
Prof. C. J. Lawn (Queen Mary College, University of London)
T. Lieuwen, USA (Georgia Tech)
Kun Luo (Zhejiang University)
F. Nicoud, France (Montpellier)
M.V. Panchagnula, India (Indian Institute of Technology Madras)
J. Park, Korea (Pukyong National University)
W. Polifke, Germany (TU Munich)
B. Schuermans, Switzerland (Alstom)
C. Willert, Germany (DLR Köln)
Prof. Vladimir E. Zarko, Russia (Institute of Chemical Kinetics and Combustion)
K.H. Yu (Maryland)
Journal submission can be made to firstname.lastname@example.org