k-epsilon equation for compressible reciprocating engine flows
The k-epsilon model currently is being used by several investigators as a submodel for the calculation of turbulent flows in engines using multidimensional procedures. As this submodel mainly was developed and tested for incompressible flows, attempts were made and described in the literature to modify the model to suit engine applications. In these attempts, little effort was made to examine the basic k and epsilon equations closely. Because these equations contain information that could be quite helpful in developing the model. In the present study the basic k and epsilon equations are examined with an analysis tailored to identify important terms that appear during compression/expansion in engine cylinders. It transpires from the analysis that some terms that were neglected basically in earlier studies could be quite large. Modeling some of these terms in the epsilon equation was relatively straightforward and did not add any unknown constants. Thus, these terms were added to the epsilon equation in the new model. The remaining terms, which are significant only during combustion, are more complex, and it is doubtful that they could be modeled without the addition of model constants. Because of a lack of data necessary to estimate the model constants, these terms were neglected. A comparison between the new and an earlier version of the model revealed that the new version yielded more physically plausible results.
- Research Organization:
- General Motors Research Laboratories, Warren, Michigan
- OSTI ID:
- 6497275
- Journal Information:
- J. Energy; (United States), Vol. 7:4
- Country of Publication:
- United States
- Language:
- English
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