Numerical Investigation of Transversely Injected Pulsed Jets in a Supersonic Flow PDF Download
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Author: Touraj Sahely
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 154
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Book Description
Author: Touraj Sahely
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 154
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Book Description
Author: Nehemiah Joel Williams
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 186
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Book Description
The investigation of fuel delivery mechanisms is a critical design point in the development of supersonic combustion ramjet (scramjet) technology. Primary challenges include proper penetration of the jet in the supersonic crossflow while keeping total pressure losses and wall drag to a minimum. To reduce drag and heat loads especially at high burner entry Mach numbers it is desirable to use a minimally intrusive means of fuel delivery. Pulsation of gaseous jets has been shown to increase penetration and mixing in subsonic flows. A limited number of experimental studies and even fewer numerical studies have suggested that when applied to supersonic crossflows, gaseous jets pulsed in the kilohertz range of frequencies improve jet penetration and mixing. To improve on the limited number of numerical studies of pulsed jets in supersonic crossflows (PJISF), 2D and 3D computational fluid dynamics (CFD) simulation models of non-excited (steady) and sinusoidally excited (pulsed) jets were constructed using ANSYS FLUENT 15.0. The 2D investigation included pulsation at 8,16, 32 and 48 kHz. These simulation results showed that pulsation at 16 kHz provided the best jet penetration improvement in the jet near field and far field among all frequencies sampled. A 3D wall-modeled Large Eddy Simulation (WMLES) was constructed with the goals resolving large scale turbulent flow structure and observing the time evolution of a jet pulsed in a supersonic crossflow, as well as to compare the effects of sinusoidal pulsation at 16 kHz with steady injection for the same flow conditions as the 2D case. A comparison of the jet trajectories between the steady and pulsed injection cases demonstrated that for sinusoidal pulsation of a jet at 16 kHz over the equivalent cycle averaged injection total pressure and momentum flux ratio, jet penetration is improved over the steady jet, up to 50% in the near field of the jet. Furthermore, improved mass concentration decay associated with jet-crossflow mixing and far field total pressure recovery has been demonstrated as a result of pulsation of the jet.
Author: Mingbo Sun
Publisher: Springer
ISBN: 9811360251
Category : Technology & Engineering
Languages : en
Pages : 284
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Book Description
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.
Author: Steven W. Clark
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Steven W. Clark
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 106
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Author: Leo Patrick O'Hare
Publisher:
ISBN:
Category :
Languages : en
Pages : 206
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Author: Mostafa Barzegar Gerdroodbary
Publisher: Butterworth-Heinemann
ISBN: 0128211407
Category : Technology & Engineering
Languages : en
Pages : 230
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Book Description
Scramjet engines are a type of jet engine and rely on the combustion of fuel and an oxidizer to produce thrust. While scramjets are conceptually simple, actual implementation is limited by extreme technical challenges. Hypersonic flight within the atmosphere generates immense drag, and temperatures found on the aircraft and within the engine can be much greater than that of the surrounding air. Maintaining combustion in the supersonic flow presents additional challenges, as the fuel must be injected, mixed, ignited, and burned within milliseconds. Fuel mixing, along with the configuration and positioning of the injectors and the boundary conditions, play a key role in combustion efficiency. Scramjets: Fuel Mixing and Injection Systems discusses how fuel mixing efficiency and the advantage of injection systems can enhance the performance of the scramjets. The book begins with the introduction of the supersonic combustion chamber and explains the main parameters on the mixing rate. The configuration of scramjets is then introduced with special emphasis on the main effective parameters on the mixing of fuel inside the scramjets. In addition, basic concepts and principles on the mixing rate and fuel distribution within scramjets are presented. Main effective parameters such as range of fuel concentration for the efficient combustion, pressure of fuel jet and various arrangement of jet injections are also explained. This book is for aeronautical and mechanical engineers as well as those working in supersonic combustion who need to know the effects of compressibility on combustion, of shocks on mixing and on chemical reactions, and vorticity on the flame anchoring. Explains the main applicable approaches for enhancement of supersonic combustion engines and the new techniques of fuel injection Shows how the interaction of main air stream with fuel injections can develop the mixing inside the scramjets Presents results of numerical simulations and how they can be used for the development of the combustion engines
Author: Mark P. Wilson
Publisher:
ISBN: 9781423583189
Category : Airplanes
Languages : en
Pages : 159
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Book Description
In pursuit of more efficient and effective fuel-air mixing for a SCRAMJET combustor, this study was conducted to investigate relative near field enhancements of penetration and mixing of a discrete low-angled (25 deg) injected air jet into a supersonic (M=2.9) cross flow. The enhancements were achieved by injecting the transverse air jet parallel to the compression face of eight different ramp geometries. The jet-ramp interactions created collinear shock structures, baroclinic torque vorticity enhancement, ramp spillage enhanced vorticity, magnus effect penetration enhancement, and increased total pressure loss. Shadowgraph photography was used to identify the shock structures and interactions in the flow field. Measurements of mean flow properties were used to establish the jet plume size, jet plume penetration and to quantify the total pressure loss created by the ramps. Rayleigh-Mie scattering images were used for both qualitative flow field assessments and quantitative analysis of the plume trajectory and mixing rate. Results indicate that up to a 20% increase in penetration height and plume expansion can be achieved by injection over a ramp compared to simple transverse injection. This increase in penetration and mixing incurs up to a 15% loss in total pressure. The most critical geometric aspects that affect the flow are the ramp compression face shape and frontal aspect, and the location and strength of ramp generated expansion.
Author: Alfredo de Gregorio de Juan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Jain-Ming Wu
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 13
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