Figure 26. Effect of increased fluid viscosity on flow circulation/heat removal.

the interfaces (even for the tapered surface design), combined with the relatively poor thermal properties of the oil, result in a sharp (84%) decrease in heat removal, relative to the case for water (Figure 15).

Summary and Conclusions

The thermofluid design of dual mechanical seals used to prevent leakage from rotating shafts in industrial fluid-handling equipment was investigated. The purpose of the study was to examine effects of various design and operational parameters on convective removal of friction-generated heat within the seal itself. Using Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD), confirmed by laboratory testing, the performance of virtual prototypes was examined to evaluate the effectiveness and thermal efficiency of barrier fluid flows.

As anticipated, the results show that axial circulation of fluid to and from warmer regions within the seals promotes heat removal. Design features favoring axial circulation include larger radial gaps between rotating and stationary components, as well as axially-tapered surfaces which act to propel cooler fluid toward the heat-producing interfaces of the seal. Other conditions found to improve the cooling performance of barrier fluids are increased speed of shaft rotation, larger rates of barrier fluid throughflow, and fluids having lower viscosities such as water and Ethylene-Glycol/water mixtures.

The findings revealed by this study have helped guide the design of cooler-operating, longer-lasting dual mechanical seal. Much of the credit for the success of the project is attributed to the versatile and novel ways in which the computed CFD data could be visualized and more clearly understood using the unique capabilities of Data Explorer.

Acknowledgements

The authors would like to express their thanks to the following individuals whose efforts helped make this work possible: Kevin McArthur, Paul Philippon, Bo Ruan, Shifeng Wu, and John Yurka, A. W. Chesterton Co.; Liz Marshall, Fluent Inc.; Greg Abram, Rob Look, Holly Rushmeier, Rich Sefecka, and Lloyd Treinish IBM Visualization Data Explorer; Chris Doehlert; and Dan Freund and Mark Smith, Silicon Graphics.