Controlling Volumetric Heat Release Rates in a Dump Combustor Using Countercurrent Shear

AIAA Journal ◽  
2007 ◽  
Vol 45 (6) ◽  
pp. 1317-1323 ◽  
Author(s):  
A. A. Behrens ◽  
P. J. Strykowski
Keyword(s):  
Heat Release ◽  
Release Rates ◽  
Dump Combustor ◽  
Countercurrent Shear

Enhancing Combustion in a Dump Combustor Using Countercurrent Shear: Part 2 — Heat Release Rate Measurements and Geometry Effects

2005 ◽  
Author(s):  
Alison A. Behrens ◽  
Matthew J. Anderson ◽  
Paul J. Strykowski ◽  
David J. Forliti
Keyword(s):  
Heat Release ◽  
Shear Layer ◽  
Recirculation Zone ◽  
Rectangular Channel ◽  
Sudden Expansion ◽  
Flame Surface ◽  
Release Rates ◽  
Primary Flow ◽  
Dump Combustor ◽  
Countercurrent Shear

Research to advance our understanding of the countercurrent shear flow has been conducted, with particular emphasis on those characteristics of countercurrent shear that are beneficial for combustion applications. Studies carried out in a backward-facing step combustor burning prevaporized JP10-air mixtures, have examined the implementation of counterflow as a means to enhance turbulent burning velocities, with the overall objective of increasing volumetric heat release rates and thereby create a more compact combustion zone. The dump combustor is characterized by a nominally two-dimensional primary flow mixture of prevaporized fuel and air, entering a rectangular channel before encountering a 2:1 single-sided step expansion. Flow separation over the sudden expansion and the resulting recirculation set up a countercurrent shear layer downstream of the dump plane and a low velocity zone conducive to flame anchoring. Combustion control strategies aim to increase turbulent kinetic energy and flame three-dimensionality in an effort to increase flame surface area and thus burning rates. A secondary flow is created via suction at the dump plane as a fluidic control mechanism to enhance the naturally occurring countercurrent shear layer. Counterflow is shown to elevate turbulence levels and volumetric heat release rates downstream of the step in the base geometry while concomitantly reducing the scale of the recirculation zone[1]. Modifications to the rearward-facing step geometry are investigated using Particle Image Velocimetry (PIV) under isothermal flow conditions in an effort to extend the near field interaction between the recirculation zone and the incoming primary flow, thus exploiting the benefits of counterflow as seen in the base geometry. Using chemiluminescence, relative heat release rates are shown to increase by 90% with a counterflow level of 6% of the primary flow by mass in the base geometry, and a 150% increase with a counterflow level of 2.4% in the modified step geometry.

Species production and heat release rates in two-layered natural gas fires

1991 ◽  
Vol 83 (3-4) ◽  
pp. 325-332 ◽  
Author(s):  
E.E. Zukoski ◽  
J.H. Morehart ◽  
T. Kubota ◽  
S.J. Toner
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Release Rates ◽  
Species Production

Heat release rates from heavy goods vehicle trailer fires in tunnels

2005 ◽  
Vol 40 (7) ◽  
pp. 646-668 ◽  
Author(s):  
Haukur Ingason ◽  
Anders Lönnermark
Keyword(s):  
Heat Release ◽  
Release Rates

scholarly journals Oxygen-Enriched Diesel Engine Performance: A Comparison of Analytical and Experimental Results

1991 ◽  
Vol 113 (3) ◽  
pp. 365-369 ◽  
Author(s):  
R. R. Sekar ◽  
W. W. Marr ◽  
D. N. Assanis ◽  
R. L. Cole ◽  
T. J. Marciniak ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Experimental Studies ◽  
Engine Performance ◽  
Oxygen Enrichment ◽  
Published Data ◽  
Particulate Emissions ◽  
Lower Grade ◽  
Nox Emissions ◽  
Release Rates

Use of oxygen-enriched combustion air in diesel engines can lead to significant improvements in power density, as well as reductions in particulate emissions, but at the expense of higher NOx emissions. Oxygen enrichment would also lead to lower ignition delays and the opportunity to burn lower grade fuels. Analytical and experimental studies are being conducted in parallel to establish the optimal combination of oxygen level and diesel fuel properties. In this paper, cylinder pressure data acquired on a single-cylinder engine are used to generate heat release rates for operation under various oxygen contents. These derived heat release rates are in turn used to improve the combustion correlation—and thus the prediction capability—of the simulation code. It is shown that simulated and measured cylinder pressures and other performance parameters are in good agreement. The improved simulation can provide sufficiently accurate predictions of trends and magnitudes to be useful in parametric studies assessing the effects of oxygen enrichment and water injection on diesel engine performance. Measured ignition delays, NOx emissions, and particulate emissions are also compared with previously published data. The measured ignition delays are slightly lower than previously reported. Particulate emissions measured in this series of tests are significantly lower than previously reported.

Upholstered Furniture Heat Release Rates: Measurements and Estimation

1983 ◽  
Vol 1 (1) ◽  
pp. 9-32 ◽  
Author(s):  
Vytenis Babrauskas
Keyword(s):  
Heat Release ◽  
Quantitative Assessment ◽  
Fire Testing ◽  
Flame Resistance ◽  
Release Rates ◽  
New Instrument ◽  
Upholstered Furniture ◽  
Rate Information ◽  
Furniture Calorimeter ◽  
Design Factors

A new instrument, termed a furniture calorimeter, has been constructed and placed into operation for measuring furniture heat release rates based on oxygen consumption. Using the furniture calorimeter, burning rate information has been obtained on a series of 13 chairs, loveseats, and sofas, most of them specially built to permit direct comparisons of construction features. A quantitative assessment is made of the effect of fabric types, padding types (cotton batting, ordinary polyurethane foam, and California-requirements foam), and frame types. The advantages of furniture calorimeter testing over normal room fire testing are discussed. Based on these measurements, a rule is presented for estimating the heat release rate based on design factors. Finally, implications for achieving both good flame resistance and good cigarette ignition resistance are discussed.

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