Author: Krishna Lakshminarasimhan
Publisher:
ISBN:
Category :
Languages : en
Pages : 246
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Book Description
Previous and current work show that flame length and soot luminosity of laminar and turbulent nonpremixed jet flames can be significantly reduced by high-frequency, high-amplitude forcing of the fuel flow rate. The current work focuses on understanding the physical mechanisms responsible for these changes to the flow/flame structure for the case where the forcing is sufficiently strong that significant reverse flow exists at the exit of the fuel delivery tube. The high-amplitude forcing is achieved by pulsing the fuel at the organ-pipe resonance frequency of the fuel delivery tube. Quantitative mixture fraction imaging in nonreacting jets indicates that the strongly pulsed jets exhibit dramatically enhanced mixing as compared to unpulsed jets. In the pulsed jets the mean mixture fraction falls below 0.08 in as little as 3 diameters downstream of the nozzle exit and no pure jet fluid exists outside of the nozzle due to in-tube mixing. Simultaneous OH and acetone planar laser induced fluorescence (PLIF) performed in methane jet flames shows that the OH zones are much broader and more wrinkled in the resonantly pulsed jet as compared to the unpulsed jet, and are greatly contorted by the vortical structures. A unique feature of the pulsed flames is that the reaction zones appear to close downstream of a vortical structure, just a few diameters downstream of the nozzle exit, in a region where the mixture fraction imaging (for non-reacting flows) shows reduced mixture fraction. Furthermore, the flame anchors on the outer-upstream edge of the vortical structures where the fuel mixture fraction is reduced due to enhanced entrainment. The significant in-tube premixing and the enhanced entrainment appear to be the predominant mechanisms that cause the reduction in length and luminosity of high-amplitude, high-frequency pulsed nonpremixed jet flames.
Author: Tim C. Lieuwen
Publisher: Cambridge University Press
ISBN: 1107015995
Category : Science
Languages : en
Pages : 427
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Book Description
This book deals with unsteady combustor issues, which have posed key challenges associated with development of clean, high-efficiency combustion systems.
Author:
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 138
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Book Description
Author: Nedunchezhian Swaminathan
Publisher: Cambridge University Press
ISBN: 1139498584
Category : Technology & Engineering
Languages : en
Pages : 447
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Book Description
A work on turbulent premixed combustion is important because of increased concern about the environmental impact of combustion and the search for new combustion concepts and technologies. An improved understanding of lean fuel turbulent premixed flames must play a central role in the fundamental science of these new concepts. Lean premixed flames have the potential to offer ultra-low emission levels, but they are notoriously susceptible to combustion oscillations. Thus, sophisticated control measures are inevitably required. The editors' intent is to set out the modeling aspects in the field of turbulent premixed combustion. Good progress has been made on this topic, and this cohesive volume contains contributions from international experts on various subtopics of the lean premixed flame problem.
Author: Vinayak Vidyadhar Barve
Publisher:
ISBN: 9780549052555
Category :
Languages : en
Pages : 282
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Book Description
Unforced and strongly forced cold-flow jets are simulated using a higher order finite volume CFD code. The jet was forced by varying the jet exit velocity over a range of forcing amplitudes and frequencies and it was found that the jet Strouhal number (St) was the important parameter in characterizing flowfield development. Further, the forced jets showed increased entrainment and increased entrainment rates as compared to the non-forced jets.
Author: David Anthony Cicoria
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 198
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Book Description
Author: Fabrizio Bisetti
Publisher:
ISBN:
Category :
Languages : en
Pages : 582
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Book Description
Author: Mitchell D. Smooke
Publisher: Springer
ISBN:
Category : Science
Languages : en
Pages : 264
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Book Description
In this comprehensive text a systematic numerical and analytical treatment of the procedures for reducing complicated systems to a simplified reaction mechanism is presented. The results of applying the reduced reaction mechanism to a one-dimensional laminar flame are discussed. A set of premixed and non-premixed methane-air flames with simplified transport and skeletal chemistry are employed as test problems that are used later on to evaluate the results and assumptions in reduced reaction networks. The first four chapters form a short tutorial on the procedures used in formulating the test problems and in reducing reaction mechanisms by applying steady-state and partial-equilibrium approximations. The final six chapters discuss various aspects of the reduced chemistry problem for premixed and nonpremixed combustion.
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 1006
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Book Description
Author: Hiroshi Tsuji
Publisher: CRC Press
ISBN: 1420041037
Category : Nature
Languages : en
Pages : 425
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Book Description
Maximize efficiency and minimize pollution: the breakthrough technology of high temperature air combustion (HiTAC) holds the potential to overcome the limitations of conventional combustion and allow engineers to finally meet this long-standing imperative. Research has shown that HiTAC technology can provide simultaneous reduction of CO2 and nitric
