This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
LDV Measurements of Velocities and Turbulence Intensities in a Production SI Engine Under Motored and Firing Conditions
Technical Paper
1999-01-0955
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Laser Doppler Velocimetry (LDV) was used to make measurements of velocities and turbulence intensities at a location near the wedge-type combustion chamber center in a production SI engine under motored and firing conditions. The ensemble-averaged and conditionally-sampled data-processing techniques were employed to investigate the raw velocity data for motored and firing conditions respectively.
The turbulence field measured under firing conditions is different from the motored data only after the spark ignition begins. There exists a dramatic change in ensemble-averaged mean velocity in the direction of flame propagation due to the fast volume expansion of burned gas when the flame front pass through the measurement point. Initially, the flame moves away from the spark plug and toward the measurement point, pushing the unburned gas ahead of it. Passage of the flame induces a horizontal velocity in the opposite direction. After the flame passes the measurement point, a sharp increase in horizontal velocity occurs ahead of the flame as the burned gas expands into the chamber, pushing the unburned gas ahead of it. After the flame has passed the measurement point, the sharp increase in velocity is followed by a marked drop in velocity behind the flame, as the fresh mixture burned in the flame region expands compressing both the burned and unburned gases. Gradually the velocity increases again due to the angular momentum of the swirl.
Conditional sampling on the crank shaft angle of maximum pressure revealed that the engine cycles with smaller crank shaft angle of maximum pressure had higher burning rates and had mean velocities changing dramatically in the direction of flame propagation when the flame passed through the measurement point, suggesting a correlation between the turbulence intensity at time of ignition and the crank angle of maximum pressure. Furthermore, there exist different turbulence flow fields in the burned and unburned gas regions, suggesting different analytical techniques should be used to resolve the cyclic variations in the two regions.
Recommended Content
Authors
Citation
Liu, R., Liu, W., Wu, L., and Zhao, C., "LDV Measurements of Velocities and Turbulence Intensities in a Production SI Engine Under Motored and Firing Conditions," SAE Technical Paper 1999-01-0955, 1999, https://doi.org/10.4271/1999-01-0955.Also In
In-Cylinder Velocity Measurements, Combustion, and Flow Diagnostics
Number: SP-1446; Published: 1999-03-01
Number: SP-1446; Published: 1999-03-01
References
- Lancaster, D.R. Krieger, R.B. Sorenson, S.C. Hull, W.L. Effects of Turbulence on Spark-Ignition Engine Combustion SAE paper 760160
- Hamamoto, Y. Hisao, O. Yamamoto, H. Sugahara, R. Effects of Turbulence on Combustion of Homogeneous Mixture of Fuel and Air in a Closed Vessel Bulletin of JSME 27 226 April 1984
- Groff, E.G. Matekunas, F.A. The Nature of Turbulent Flame Propagation in a Homogeneous Spark-Ignition Engine SAE paper 800133
- Lorenz, M. Prescher, K. Cycle Resolved LDV Measurements on a Fired SI-Engine at High Data Rates Using a Conventional Modular LDV-System SAE paper 900054
- Catania, A.E. Mittica, A. Extraction Techniques and Analysis of Turbulence Quantities from In-Cylinder Velocity Data Trans. of the ASME 111 July 1989
- Liou, T.M. Santavicca, D.A. Cycle-Resolved LDV measurements in a motored IC Engine Trans. of The ASME 107 June 1985
- Fansler, T.D. French, D.T. Cycle-Resoled Laser-Velocimetry Measurements in a Reentrant-Bowl-in-Piston Engine SAE paper 880377
- Witze, P.O. Martin, J.K. Borgnakke, C. Fluid Motion during Flame Propagation in a Spark Ignition Engine SAE paper 840377
- Witze, P.O. Martin, J.K. Borgnakke, C. Conditionally-Sampled Velocity and Turbulence Measurements in a Spark Ignition Engine Combustion Science and Technology 34 1984 301 317
- Hall, M.J. Bracco, F.V. A Study of Velocities and Turbulence Intensities Measured in Firing and Motored Engines SAE paper 870453