Contacting mechanical seal design using a simplified hydrostatic model

Abstract

While hydrostatic theory of mechanical face seal operation is well understood, there has always been some difficulty in applying this idea to the design of seals that contact. In this paper, a simple mixed friction model of seal load support is formulated. Surface roughness is an essential parameter. Mechanical contact load support and hydrostatic load support are both considered. Load support equilibrium is always satisfied. The minimum film thickness and leakage are found. Considering both fluid and mechanical contact friction, the total power consumption is found. The model works equally well for convergent or divergent films. This model is combined with both thermally—caused and pressure—caused radial taper effects using a simple relationship. Using very few algebraic equations, one can solve for the equilibrium operating conditions for practical seals. Design guidelines concenrning balance ratio, presure rotation coefficient, thermal rotation coefficient, and initial taper are developed by studying various nondimensional parameters which arise from this simple model. Typical seal performance is predicted and compared to some experimental data. The model can be easily used by others and provides immediate and practical results for seal design.