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Reacting Boundary Layers in Homogeneous Charge Compression Ignition (HCCI) Engine

Hultqvist, Anders LU ; Engdar, Ulf LU ; Johansson, Bengt LU and Klingmann, Jens LU (2001) SAE World Congress, 2001 In SAE Transactions p.1086-1098
Abstract
An experimental and computational study of the nearwall

combustion in a Homogeneous Charge

Compression Ignition (HCCI) engine has been conducted

by applying laser based diagnostic techniques in

combination with numerical modeling. Our major intent

was to characterize the combustion in the velocity- and

thermal boundary layers. The progress of the combustion

was studied by using fuel tracer LIF, the result of which

was compared with LDA measurements of the velocity

boundary layer along with numerical simulations of the

reacting boundary layer.

Time resolved images of the PLIF signal were taken and

ensemble averaged images were... (More)
An experimental and computational study of the nearwall

combustion in a Homogeneous Charge

Compression Ignition (HCCI) engine has been conducted

by applying laser based diagnostic techniques in

combination with numerical modeling. Our major intent

was to characterize the combustion in the velocity- and

thermal boundary layers. The progress of the combustion

was studied by using fuel tracer LIF, the result of which

was compared with LDA measurements of the velocity

boundary layer along with numerical simulations of the

reacting boundary layer.

Time resolved images of the PLIF signal were taken and

ensemble averaged images were calculated. In the fuel

tracer LIF experiments, acetone was seeded into the fuel

as a tracer. It is clear from the experiments that a proper

set of backgrounds and laser profiles are necessary to

resolve the near-wall concentration profiles, even at a

qualitative level. Partial resolution of the velocity

boundary layer was enabled by using a slightly inclined

LDA probe operated in back-scatter mode. During these

conditions, it was possible to acquire velocity data within

0.2 mm from the wall. A one-dimensional model of the

flow field was devised to make the connection between

the thermal and the velocity boundary layer.

The investigations suggest that wall interaction is not the

responsible mechanism for the rather high emissions of

unburned hydrocarbons from HCCI engines. It is

believed that the delayed oxidation, indicated by the fuel

tracer LIF experiments and numerical simulations, is due

to the thermal boundary layer. From the data at hand, it

is concluded that the thermal boundary layer is on the

order of 1 mm thick. In this boundary layer the reactions

are delayed but not quenched. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
in
SAE Transactions
pages
1086 - 1098
publisher
SAE
conference name
SAE World Congress, 2001
language
English
LU publication?
yes
id
2754f4b0-6484-4457-b65e-246464a80778 (old id 1041088)
alternative location
http://www.sae.org/technical/papers/2001-01-1032
date added to LUP
2008-03-03 08:18:02
date last changed
2016-04-16 09:20:42
@misc{2754f4b0-6484-4457-b65e-246464a80778,
  abstract     = {An experimental and computational study of the nearwall<br/><br>
combustion in a Homogeneous Charge<br/><br>
Compression Ignition (HCCI) engine has been conducted<br/><br>
by applying laser based diagnostic techniques in<br/><br>
combination with numerical modeling. Our major intent<br/><br>
was to characterize the combustion in the velocity- and<br/><br>
thermal boundary layers. The progress of the combustion<br/><br>
was studied by using fuel tracer LIF, the result of which<br/><br>
was compared with LDA measurements of the velocity<br/><br>
boundary layer along with numerical simulations of the<br/><br>
reacting boundary layer.<br/><br>
Time resolved images of the PLIF signal were taken and<br/><br>
ensemble averaged images were calculated. In the fuel<br/><br>
tracer LIF experiments, acetone was seeded into the fuel<br/><br>
as a tracer. It is clear from the experiments that a proper<br/><br>
set of backgrounds and laser profiles are necessary to<br/><br>
resolve the near-wall concentration profiles, even at a<br/><br>
qualitative level. Partial resolution of the velocity<br/><br>
boundary layer was enabled by using a slightly inclined<br/><br>
LDA probe operated in back-scatter mode. During these<br/><br>
conditions, it was possible to acquire velocity data within<br/><br>
0.2 mm from the wall. A one-dimensional model of the<br/><br>
flow field was devised to make the connection between<br/><br>
the thermal and the velocity boundary layer.<br/><br>
The investigations suggest that wall interaction is not the<br/><br>
responsible mechanism for the rather high emissions of<br/><br>
unburned hydrocarbons from HCCI engines. It is<br/><br>
believed that the delayed oxidation, indicated by the fuel<br/><br>
tracer LIF experiments and numerical simulations, is due<br/><br>
to the thermal boundary layer. From the data at hand, it<br/><br>
is concluded that the thermal boundary layer is on the<br/><br>
order of 1 mm thick. In this boundary layer the reactions<br/><br>
are delayed but not quenched.},
  author       = {Hultqvist, Anders and Engdar, Ulf and Johansson, Bengt and Klingmann, Jens},
  language     = {eng},
  pages        = {1086--1098},
  publisher    = {ARRAY(0x8766fa0)},
  series       = {SAE Transactions},
  title        = {Reacting Boundary Layers in Homogeneous Charge Compression Ignition (HCCI) Engine},
  year         = {2001},
}