Download or read book Studies of Turbulent Mixing and Combustion in Supersonic Heterogeneous Flows written by Kenneth N. C. Bray and published by . This book was released on 1971 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the program was the development of analytical models of various flow configurations which can be used in the design of supersonic air-breathing propulsion systems. The work described in the report represents an extension of earlier studies in the program to conditions that exist in air-augmented rocket systems. These conditions vary according to the nature of the rocket propellant, as liquid propellants usually produce only gaseous fuel-rich combustion products whereas solid propellant rockets emit heterogeneous products which contain small combustible particles. The inclusion of particles produces significant effects upon reacting turbuelent flows, particularly when the particles themselves continue to burn. Some predictions of their behavior in a reacting flow field are presented. A series of systematic tests has been planned by which the experimental conditions proceed stepwise through conditions of increasing primary stream (rocket exhaust) complexity starting with a cold nonreactive gas and ending with a hot, reactive, heterogeneous mixture. The method permits the effects of temperature, of gaseous combustion and solid combustion upon a supersonic, reacting flow field to be isolated. Results obtained from the experimental tests are presented, and some conclusions are drawn from the data. (Author).
Download or read book Ignition and Sustaining of Combustion by Energy Addition in Turbulent Supersonic Flow written by Kenneth N. C. Bray and published by . This book was released on 1970 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the study is to obtain data on turbulent, supersonic combustion which will facilitate development of ignition systems for use in scramjet engines under conditions when combustion cannot occur spontaneously. To this end a simple analytical model of a reacting, turbulent flow is presented, based upon the a priori assumption that combustion and turbulent mixing can be uncoupled. Predictions from this model are compared with some new experimental data on the ignition of ethylene in air. Both premixed and unpremixed situations are included. Tests of the validity of the mixing model are made for the nonreacting case by comparing predicted and measured velocity profiles in a duct; a satisfactory agreement is obtained. The predicted ignition requirements also match the measured values in most cases, with mixing- and reaction-rate data taken from the literature. Until uncertainties in these mixing- and reaction-rate expressions can be substantially reduced, the use of more subtle coupling models in the determination of ignition requirements does not appear to be justified. A much simpler model is also presented and used to derive a useful criterion for the prediction of the ignition boundaries in premixed fuel-air flows. (Author).
Download or read book Turbulent Reacting Flows and Supersonic Combustion written by C. T. Bowman and published by . This book was released on 1990 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation of supersonic combustion flows was carried out. The principal objective of the research was to gain a more fundamental understanding of mixing and chemical reaction in supersonic flows. The research effort comprised three inter-related elements: (1) an experimental study of mixing and combustion in a supersonic plane mixing layer; (2) development of laser-induced fluorescence techniques for time-resolved two-dimensional imaging of species concentration, temperature and velocity; and (3) numerical simulations of compressible reacting flows. The specific objectives and the results of the research is summarized. Keywords: Turbulent reacting flow; Supersonic combustion. (jhd).
Download or read book Mixing Chemical Reactions and Combustion in High Speed Turbulent Flows written by P. E. Dimotakis and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focuses on fundamental investigations of mixing, chemical-reaction, and combustion, in turbulent, subsonic, and supersonic flows. It is comprised of an experimental effort; an analytical, modeling, and computational effort; and a diagnostics- and instrumentation-development effort. Computational studies are focusing on fundamental issues pertaining to hydrocarbon ignition and combustion as well as investigations of the Rayleigh-Taylor instability.
Download or read book Supersonic Mixing and Combustion of Coaxial Hydrogen Air Streams in a Duct written by James E. Drewry and published by . This book was released on 1971 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: A basic investigation of supersonic mixing and combustion which is relevant to advanced propulsion concepts for a high Mach number, high altitude flight regime is described. A method of laboratory simulation is employed which is considered to be suitable for fundamental studies of diffusional-controlled mixing and combustion of confined coaxial streams of hydrogen and air under conditions approaching those of actual flight. A unique test facility consisting of a gas-fired, ceramic-brick air storage heater and an electrical-resistance hydrogen heater was used to generate test flow conditions at low static pressures, over wide ranges of temperature and velocity. Research studies have been carried out to obtain basic flow field data pertinent to the problem of turbulent mixing and combustion of heterogeneous gas streams under these conditions. Auto-ignition data from tests involving sustained combustion at an air Mach number of 2.6 are also presented. (Author).
Download or read book Mixing Chemical Reactions and Combustion in Subsonic and Supersonic Turbulent Flows written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research conducted under sponsorship of this grant focused on fundamental investigations of mixing, chemical-reaction, and combustion processes, in turbulent, subsonic, and supersonic flows. Research on hydrocarbon-combustion extended previous work highlighting deficiencies in existing chemical-kinetics models for ethylene combustion. Experiments in the 2- and 3-D structure and mixing of turbulent transverse jets yielded new results on isotropy and Reynolds number effects. Work in high-speed flows and subsonic-diffusers demonstrated considerable control via mass injection. Direct numerical simulations of Rayleigh-Taylor instability flows attained the highest Reynolds numbers to date yielding results on mixing and over-all growth rates. Image Correlation Velocimetry was applied to free jets and OH-tagged lines. Advances in high-performance digital-imaging systems were implemented, permitting high frame-rate and high-resolution multi-dimensional data acquisition in many of the experiments.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimization of Passive Flow Control Technique for Enhanced Turbulent Mixing in Supersonic Propulsion written by Andrious Nelson and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Author's abstract: Scramjets are supersonic combustion ramjets where there is no mechanical compressor to compress air for combustion. The technology behind engines flying at supersonic speeds has been explored since 1947. It has been in only recent years where the computational power is great enough to handle the challenges. One main challenge with engines is the problem of efficiency. The research conducted explores the background information of scramjets and significant flow field characteristics to optimize the turbulent mixing efficiency. A computational domain was chosen based on a study that revealed that adding dimpled surfaces upstream of a cavity flame holder would suppress pressure oscillations. Suppressing pressure oscillations causes less damage done to the structure of the scramjet engine and reduce the aeroacoustics generated. The research done intends to optimize the dimple diameter and dimple depth to increase mixing found in the cavity. Eight models were created by increasing or decreasing the dimple diameter from 20 mm and increasing the dimple depth from 6 mm. Each case was simulated at freestream velocities, 25 m/s, 35 m/s, 45 m/s, and 55m/s. The velocity contour and vectors showed that the L/D ratio of less than 10 followed the same characteristics of an open cavity where there are two main recirculation regions found in the cavity. Analyzing the pressure identified that the drag inside of a scramjet engine is less when there are dimpled surfaces. Turbulent eddy dissipation and turbulent eddy frequency confirmed that there were recirculation regions of larger eddies found inside the dimples. The skin friction coefficient revealed that adding dimples, increased flow separation in the cavity close to the trailing edge and adds flow separation or mixing at the dimples. To reduce drag and increase mixing in the scramjet engine case Dia20d10 was chosen. This case showed no apparent effects due to increased freestream velocity along the trailing edge of the cavity and increased mixing at the leading edge.
Download or read book Chemical Reactions in Turbulent Mixing Flows written by and published by . This book was released on 1990 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research conducted fundamental investigations of turbulent mixing, chemical reaction and combustion processes in turbulent, subsonic and supersonic flows. This program is comprised of an experimental effort, an analytical effort, a computational effort, a modeling effort, and a diagnostics development and data-acquisition effort; the latter as dictated by specific needs of the experimental part of the overall program. Our approach has been to carry out a series of detailed theoretical and experimental studies primarily in two, well-defined, fundamentally important flow fields: free shear layers and axisymmetric jets. To elucidate molecular transport effects, experiments and theory concern themselves with both liquids and gases, primarily in moderate to high Reynolds number flows. Modeling has been focused on both shear layers and turbulent jets, with an effort to include the physics of the molecular transport processes, as well as formulations of models that permit the full chemical kinetics of the combustion process to be incorporated. Our recent analytical efforts have concentrated on a hydrodynamic analysis of the stability of compressible shear layers. The computational studies are, at present, focussed at fundamental issues pertaining to the computational simulation of both compressible and incompressible flows.
Download or read book Turbulent Mixing and Combustion for High Speed Air Breathing Propulsion Applications written by and published by . This book was released on 2006 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focuses on fundamental investigations of mixing and combustion, in turbulent, subsonic, and supersonic flows and is motivated by problems in high-speed air-breathing propulsion. The work is a closely coordinated effort between experiments and numerical simulation, and exploits recent developments in diagnostics and instrumentation.
Download or read book Towards a Numerical Simulation of Supersonic Mixing Combustion written by Mohammed Kamel and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design and off-design studies of the hypersonic air-breathing engines face many challenges, due to the complexity of their internal flows. The mixing and combustion processes in Supersonic-Combustion Ramjet (scramjet) engines involve complicated aerothermochemical features, such as: the interactions between shock-waves and boundary-layer, the shock induced-combustion and the recirculation zones. In this study, a numerical solver is developed and validated to be an efficient design tool capable of simulating these complicated flow features of the supersonic combustors. For the code validation, several test cases are considered to monitor the code ability to solve for the diffusive and turbulent fluxes, and the chemical source term. In addition, the code is validated by resolving the transverse sonic injection into supersonic air flow in the case of Helium injection from a flat plate, and in the case of Hydrogen injection in a single-strut scramjet engine. The effectiveness of this injection technique in mixing and flame-holding is demonstrated. The results show good agreement with the previous numerical and experimental investigations, and prove the simulator's accuracy.
Download or read book Theoretical and Experimental Investigation of Supersonic Combustion written by Antonio Ferri and published by . This book was released on 1962 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical and experimental investigation of mixing and supersonic combustion is presented. A review of the problem under investigation is given. Then an analysis of inviscid flow fields with a finite rate chemistry for a hydrogen-air reaction is presented, an an analysis of a turbulent mixing for flows with large density gradients with no chemical reaction is presented. The analysis is compared wit the experimental results. Results of the experiments in upersonic combustion are presented. (Author).
Download or read book NASA Contractor Report written by and published by . This book was released on 1978 with total page 1056 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Jet in Supersonic Crossflow written by Mingbo Sun and published by Springer. This book was released on 2019-02-18 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on research into jets in supersonic crossflow carried out by the authors’ team over the past 15 years, this book summarizes and presents many cutting-edge findings and analyses on this subject. It tackles the complicated mixing process of gas jets and atomization process of liquid jets in supersonic crossflow, and studies their physical mechanisms. Advanced experimental and numerical techniques are applied to further readers’ understanding of atomization, mixing, and combustion of fuel jets in supersonic crossflow, which can promote superior fuel injection design in scramjet engines. The book offers a valuable reference guide for all researchers and engineers working on the design of scramjet engines, and will also benefit graduate students majoring in aeronautical and aerospace engineering.
Download or read book An Investieation of Supersonic Combustion and Heterogeneous Turbulent Jet Mixing Related to the Design operation of Scram Jets written by Ian Thomas Osgerby and published by . This book was released on 1965 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Mixing in Supersonic Combustion System written by J. Swithenbank and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of Supersonic Combustion and Heterogeneous Turbulent Jet Mixing Related to the Design operation of Scramjets written by Ian Thomas Osgerby and published by . This book was released on 1965 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical kinetic calculations of the combustion time in a constant area scramjet combustion (Mo=7) indicate reaction times 0.00001 secs., and show that the combustion process is usually controlled by diffusion. The mixing process in concentric fueld/air jets is investigated by means of integral forms of the equations of motion and slow mixing requires about 50 diameter. Initial contraction of the slow inner jet is predicted by the theory, and verified by experiment. The simulation of scramjet combustion conditions by a shock tunnel is considered feasible. (Author).
