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Reacting boundary layers in a homogeneous charge compression ignition (HCCI) engine

Hultqvist, Anders LU ; Engdar, Ulf LU ; Johansson, Bengt LU and Klingmann, Jens LU (2001) SAE 2001 World Congress
Abstract

An experimental and computational study of the near-wall 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... (More)

An experimental and computational study of the near-wall 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.

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Abstract (Swedish)
An experimental and computational study of the near-wall 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... (More)
An experimental and computational study of the near-wall 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)
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author
; ; and
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
SAE Technical Papers
article number
2001-01-1032
pages
15 pages
conference name
SAE 2001 World Congress
conference location
Detroit, MI, United States
conference dates
2001-03-05 - 2001-03-08
external identifiers
  • scopus:85072470280
ISBN
0148-7191
DOI
10.4271/2001-01-1032
language
English
LU publication?
yes
id
70f12de6-04ea-4aa0-92a2-5275cd86d73a
date added to LUP
2018-10-18 12:42:53
date last changed
2021-01-04 14:53:29
@inproceedings{70f12de6-04ea-4aa0-92a2-5275cd86d73a,
  abstract     = {<p>An experimental and computational study of the near-wall 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.</p>},
  author       = {Hultqvist, Anders and Engdar, Ulf and Johansson, Bengt and Klingmann, Jens},
  booktitle    = {SAE Technical Papers},
  isbn         = {0148-7191},
  language     = {eng},
  month        = {12},
  title        = {Reacting boundary layers in a homogeneous charge compression ignition (HCCI) engine},
  url          = {http://dx.doi.org/10.4271/2001-01-1032},
  doi          = {10.4271/2001-01-1032},
  year         = {2001},
}