A Mixed Friction Hydrostatic Face Seal Model With Phase Change

1980 ◽  
Vol 102 (2) ◽  
pp. 133-138 ◽  
Author(s):  
A. O. Lebeck
Keyword(s):  
Phase Change ◽  
Design Parameters ◽  
Face Seal ◽  
Mechanical Contact ◽  
Two Phase ◽  
Mixed Friction ◽  
Mechanical Face Seal ◽  
Higher Temperature ◽  
And Performance ◽  
Very High

A mixed friction hydrostatic mechanical face seal model is presented. Load support and friction due to mechanical contact and the effect of a phase change are considered. The results show that a phase change within the seal interface leads to a greater fraction of the load being supported by fluid film pressure than for an all liquid or all gas phase seal. As seal operating temperature approaches the boiling point of the sealed fluid, very high leakage is predicted. An explanation for puffing is offered. The effect of various design parameters on two phase seal operation is examined. On a theoretical basis, operation at a higher temperature reduces seal wear rate and friction. The model can be used by seal designers to predict instability and performance for a two phase seal.

Experimental Evaluation of a Mixed Friction Hydrostatic Mechanical Face Seal Model Considering Radial Taper, Thermal Taper, and Wear

1982 ◽  
Vol 104 (4) ◽  
pp. 439-447 ◽  
Author(s):  
L. A. Young ◽  
A. O. Lebeck
Keyword(s):  
Surface Roughness ◽  
Radial Profile ◽  
Surface Characteristics ◽  
Experimental Investigations ◽  
Test Duration ◽  
Face Seal ◽  
Mixed Friction ◽  
Face Seals ◽  
Water Test ◽  
Mechanical Face Seal

In this paper the results of experimental investigations of the effects of radial taper on mechanical face seals are presented and compared to theory. The previously published theory considers the effects of thermal taper caused by a temperature gradient in the seal rings; mixed friction in the case where load support is shared between hydrostatic support and partial contact of the seal faces; surface roughness, which affects both load sharing and leakage; and wear, which alters the radial profile. Fifteen tests were run using a 100 mm diameter carbon versus tungsten carbide seal at 1800 rpm and 3.45 MPa in water. Test duration was up to 100 hr. Varying amounts of radial taper were used. Tests were run at balance ratios of 1.00 and 0.75. Initial and final surface profiles were recorded. Seal torque, leakage, and face temperatures were recorded as functions of time. Results show that theory predicts initial torque and leakage as functions of initial taper quite well, given knowledge of seal surface characteristics. Predicted equilibrium thermal taper as a function of torque for a balance ratio of 1.0 is good. For a seal having a balance ratio of 0.75, predicted equilibrium thermal rotation shows some agreement but more experimental data are needed. The results of 1.00 balance ratio tests suggest that after a long period of operation, any initial taper will be worn away and the seal would continue to operate as a parallel face seal. Results from long-term tests indicate that the wear coefficient is not a constant. While the experimental results support the basic concepts of the model, the results show where further work must be done to better understand the role of surface roughness and wear processes in mechanical face seals.

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