Experimental study on the effects of large centrifugal forces on step-stabilized flames

A. Lapsa, Werner Dahm

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Citations (Scopus)

Abstract

Results are presented from an experimental study that examines the effects of transverse accelerations as large as ±5000 g's on premixed combustion stabilized at a backward-facing step. Large centripetal accelerations are induced by flowing a premixed reactant stream - in this case a propane-air mixture - at various speeds through a curved channel. The resulting centrifugal forces act on the high-density reactants and low-density products and have profound effects on the reactant/product mixing, flame propagation mechanisms, and the resulting blowout limits. A backward-facing step placed on either the radially inner or outer boundary of the flow channel is used to stabilize the flame. The flow speed, equivalence ratio, step height and step position are systematically varied, and shadowgraph and chemiluminescence imaging are used to reveal the effects of the transverse acceleration. Negative accelerations, where the step is placed on the inner circumference of the flow path, act to inhibit the mixing of reactants into the recirculation zone and lead to incomplete combustion. Positive accelerations, where the step is placed on the outer circumference of the flow path, dramatically enhanced the mixing between reactants and products. In this case the flame propagation angle, which is driven primarily by "centrifugal pumping", is found to be independent of the flow velocity. In the non-ideal environment of the laboratory combustor, the blowout limits under a positive centrifugal field are shown to be largely comparable to those in the straight combustor, while a negative centrifugal field demonstrates significantly enhanced blowout limits.

Original languageEnglish (US)
Title of host publication5th US Combustion Meeting 2007
PublisherCombustion Institute
Pages3388-3399
Number of pages12
Volume6
ISBN (Print)9781604238112
StatePublished - 2007
Externally publishedYes
Event5th US Combustion Meeting 2007 - San Diego, United States
Duration: Mar 25 2007Mar 28 2007

Other

Other5th US Combustion Meeting 2007
CountryUnited States
CitySan Diego
Period3/25/073/28/07

Fingerprint

centrifugal force
flames
transverse acceleration
backward facing steps
circumferences
flame propagation
combustion chambers
Combustors
products
shadowgraph photography
chemiluminescence
channel flow
Propane
propane
Chemiluminescence
equivalence
Channel flow
pumping
flow velocity
Flow velocity

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physical and Theoretical Chemistry
  • Mechanical Engineering

Cite this

Lapsa, A., & Dahm, W. (2007). Experimental study on the effects of large centrifugal forces on step-stabilized flames. In 5th US Combustion Meeting 2007 (Vol. 6, pp. 3388-3399). Combustion Institute.

Experimental study on the effects of large centrifugal forces on step-stabilized flames. / Lapsa, A.; Dahm, Werner.

5th US Combustion Meeting 2007. Vol. 6 Combustion Institute, 2007. p. 3388-3399.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Lapsa, A & Dahm, W 2007, Experimental study on the effects of large centrifugal forces on step-stabilized flames. in 5th US Combustion Meeting 2007. vol. 6, Combustion Institute, pp. 3388-3399, 5th US Combustion Meeting 2007, San Diego, United States, 3/25/07.
Lapsa A, Dahm W. Experimental study on the effects of large centrifugal forces on step-stabilized flames. In 5th US Combustion Meeting 2007. Vol. 6. Combustion Institute. 2007. p. 3388-3399
Lapsa, A. ; Dahm, Werner. / Experimental study on the effects of large centrifugal forces on step-stabilized flames. 5th US Combustion Meeting 2007. Vol. 6 Combustion Institute, 2007. pp. 3388-3399
@inproceedings{d6ca49adf2b14ccd883c7a385947c716,
title = "Experimental study on the effects of large centrifugal forces on step-stabilized flames",
abstract = "Results are presented from an experimental study that examines the effects of transverse accelerations as large as ±5000 g's on premixed combustion stabilized at a backward-facing step. Large centripetal accelerations are induced by flowing a premixed reactant stream - in this case a propane-air mixture - at various speeds through a curved channel. The resulting centrifugal forces act on the high-density reactants and low-density products and have profound effects on the reactant/product mixing, flame propagation mechanisms, and the resulting blowout limits. A backward-facing step placed on either the radially inner or outer boundary of the flow channel is used to stabilize the flame. The flow speed, equivalence ratio, step height and step position are systematically varied, and shadowgraph and chemiluminescence imaging are used to reveal the effects of the transverse acceleration. Negative accelerations, where the step is placed on the inner circumference of the flow path, act to inhibit the mixing of reactants into the recirculation zone and lead to incomplete combustion. Positive accelerations, where the step is placed on the outer circumference of the flow path, dramatically enhanced the mixing between reactants and products. In this case the flame propagation angle, which is driven primarily by {"}centrifugal pumping{"}, is found to be independent of the flow velocity. In the non-ideal environment of the laboratory combustor, the blowout limits under a positive centrifugal field are shown to be largely comparable to those in the straight combustor, while a negative centrifugal field demonstrates significantly enhanced blowout limits.",
author = "A. Lapsa and Werner Dahm",
year = "2007",
language = "English (US)",
isbn = "9781604238112",
volume = "6",
pages = "3388--3399",
booktitle = "5th US Combustion Meeting 2007",
publisher = "Combustion Institute",

}

TY - GEN

T1 - Experimental study on the effects of large centrifugal forces on step-stabilized flames

AU - Lapsa, A.

AU - Dahm, Werner

PY - 2007

Y1 - 2007

N2 - Results are presented from an experimental study that examines the effects of transverse accelerations as large as ±5000 g's on premixed combustion stabilized at a backward-facing step. Large centripetal accelerations are induced by flowing a premixed reactant stream - in this case a propane-air mixture - at various speeds through a curved channel. The resulting centrifugal forces act on the high-density reactants and low-density products and have profound effects on the reactant/product mixing, flame propagation mechanisms, and the resulting blowout limits. A backward-facing step placed on either the radially inner or outer boundary of the flow channel is used to stabilize the flame. The flow speed, equivalence ratio, step height and step position are systematically varied, and shadowgraph and chemiluminescence imaging are used to reveal the effects of the transverse acceleration. Negative accelerations, where the step is placed on the inner circumference of the flow path, act to inhibit the mixing of reactants into the recirculation zone and lead to incomplete combustion. Positive accelerations, where the step is placed on the outer circumference of the flow path, dramatically enhanced the mixing between reactants and products. In this case the flame propagation angle, which is driven primarily by "centrifugal pumping", is found to be independent of the flow velocity. In the non-ideal environment of the laboratory combustor, the blowout limits under a positive centrifugal field are shown to be largely comparable to those in the straight combustor, while a negative centrifugal field demonstrates significantly enhanced blowout limits.

AB - Results are presented from an experimental study that examines the effects of transverse accelerations as large as ±5000 g's on premixed combustion stabilized at a backward-facing step. Large centripetal accelerations are induced by flowing a premixed reactant stream - in this case a propane-air mixture - at various speeds through a curved channel. The resulting centrifugal forces act on the high-density reactants and low-density products and have profound effects on the reactant/product mixing, flame propagation mechanisms, and the resulting blowout limits. A backward-facing step placed on either the radially inner or outer boundary of the flow channel is used to stabilize the flame. The flow speed, equivalence ratio, step height and step position are systematically varied, and shadowgraph and chemiluminescence imaging are used to reveal the effects of the transverse acceleration. Negative accelerations, where the step is placed on the inner circumference of the flow path, act to inhibit the mixing of reactants into the recirculation zone and lead to incomplete combustion. Positive accelerations, where the step is placed on the outer circumference of the flow path, dramatically enhanced the mixing between reactants and products. In this case the flame propagation angle, which is driven primarily by "centrifugal pumping", is found to be independent of the flow velocity. In the non-ideal environment of the laboratory combustor, the blowout limits under a positive centrifugal field are shown to be largely comparable to those in the straight combustor, while a negative centrifugal field demonstrates significantly enhanced blowout limits.

UR - http://www.scopus.com/inward/record.url?scp=77956845532&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77956845532&partnerID=8YFLogxK

M3 - Conference contribution

SN - 9781604238112

VL - 6

SP - 3388

EP - 3399

BT - 5th US Combustion Meeting 2007

PB - Combustion Institute

ER -