This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
CFD Simulation and Validation of the Flow within a Motored Two-Stroke Engine
Annotation ability available
Sector:
Language:
English
Abstract
A CFD simulation of the flow within a motored two-port loop-scavenged two-stroke engine is described. The simulation is carried out using the STAR-CD CFD code and employs a multi-block approach to simulate the flow within the transfer duct, cylinder, and exhaust duct. A moving mesh with cell layer activation-deactivation is used to represent the reciprocating piston motion. Predictions of the flow within the cylinder and at the transfer port are presented over the open cycle and are compared to an existing measured velocity field for an engine speed of 600 rpm and a delivery ratio of unity. The results show the in-cylinder flow to have a highly complex structure dominated by recirculating flow features. The in-cylinder flow is considerably affected by reverse flow through the exhaust port at exhaust port opening, and is not seen to fully establish until after bottom dead centre. In comparison to the measured flow, the global flow properties and large scale flow structures are well predicted, with detailed flow being less accurately replicated. A good correlation between measured and predicted velocity fields is achieved by exhaust port closure. Predicted transfer port efflux correlates well with the measured efflux until port opening rises to 90% of full port opening, after which the flow separation that occurs within the transfer duct is not well predicted. Accuracy of port efflux prediction improves again as the measured flow re-attaches within the duct.
Recommended Content
Authors
Topic
Citation
Raghunathan, B. and Kenny, R., "CFD Simulation and Validation of the Flow within a Motored Two-Stroke Engine," SAE Technical Paper 970359, 1997, https://doi.org/10.4271/970359.Also In
References
- Amsden A. A. O'Rourke P. J. Butler T. D. “Comparisons of Computed and Measured three-dimensional Velocity Fields in a Motored Two-Stroke Engine” SAE Paper 920418 1992
- Haworth D. C. Huebler M. S. El Tahry S. H. Matthes W. R. “Multidimensional Calculations for a Two-Stroke-Cycle Engine: A Detailed Scavenging Model Validation” SAE Paper 932712 1993
- McKinley N. R. Kenny R. G. Fleck R. “CFD Prediction of a Two-Stroke, In-Cylinder Steady Flow Field An Experimental Validation” SAE Paper 940399 1994
- KIVA-3 “A KIVA Program with Block-Structured Mesh for Complex Geometries” Los Alamos National Laboratory
- Fansler T. D. French D. T. “The Scavenging Flow Field in a Crankcase Compression Two-Stroke Engine - A Three Dimensional Laser-Velocimetry Survey” SAE Paper 920417 1992
- McKinley N. R. “Two-Stroke Engine In-Cylinder Flow Structures” Department of Mechanical Engineering, Queen's University of Belfast 1994
- Smyth J. G. Kenny R. G. Blair G. P. “Motored and Steady Flow Boundary Conditions Applied to the Prediction of Scavenging Flow in a Loop Scavenged Two-Stroke Cycle Engine” SAE Paper 900800 1990
- McKinley N. R. Fleck R. Kenny R. G. “LDV Measurements of Transfer Port Efflux Velocities in a Motored Two-Stroke Cycle Engine” SAE Paper 921694 1992
- STAR-CD 2.21 Manuals Computational Dynamics Limited 1994
- Blair G. P. “An Alternative Method for the Prediction of Unsteady Gas Flow Through the Internal Combustion Engine” SAE Paper No. 912850 1991
- Courant R. Friedrichs K. Lewy H. Transaction Report NYO-7689 Math. Ann. 100 32 1928
- Launder B. E. “Current Capabilities in Modelling Turbulence in Industrial Flows” Applied Scientific Research 48 247 269 1991
- Rodi W. Scheuerer G. “Scrutinizing the k-ε Turbulence Model Under Adverse Pressure Gradient Conditions” Transactions of ASME 108 June 1996