Computational Investigation of Coupling Guard Heating and Mitigation
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High coupling guard temperature and oil misting on a power recovery expander led to a computational fluid dynamics (CFD) investigation of air flow and heat transfer in the coupling guard. The analyses included full 360-degree geometry, varying inlet and outlet configurations, different exhaust pressures, and both including and neglecting the flange bolt heads. With bolt heads included, the predicted coupling guard surface temperatures approximately matched values measured in the field. In the particular field problem addressed here, the measured temperatures were 219 to 222°F (104- 106°C), while the CFD predicted temperature ranged from 209- 227°F (98-108°C). Among the important findings are: The moving bolt heads generate much of the heat in a coupling guard; Properly placed outlet ports can use the bolt heads as a blower, increasing air flow through the coupling guard and lowering the temperature; Small reductions in exhaust pressure can lower the coupling guard surface temperature significantly. Numerous plots, graphs, and tables give insight into the flow field inside the coupling guard. These analyses can guide the design of coupling guards with lower surface temperatures.
Jariwala, Vishal; Turner, Daryll; Hardin, James (2014). Computational Investigation of Coupling Guard Heating and Mitigation. Texas A&M University. Turbomachinery Laboratories. Available electronically from