Computational model of tandem rectangular elastomeric seals for reciprocating motion

A numerical model developed by Nikas [Nikas GK. Elastohydrodynamics and mechanics of rectangular elastomeric seals for reciprocating piston rods. Trans ASME, J Tribol 2003;125(1):60–9; Nikas GK. Determination of polymeric sealing principles for end user high reliability. Technical Report DOW-08/01 (Dowty project), Mechanical Engineering Department, Tribology Section, Imperial College London, London; 2001; Nikas GK. Theoretical study of solid back-up rings for elastomeric seals in hydraulic actuators. Tribol Int 2004;37(9):689–99; Nikas GK. Analytical study of the extrusion of rectangular elastomeric seals for linear hydraulic actuators. Proc IMechE, Pt J J Eng Tribol 2003;217(5):365–73; Nikas GK. Transient elastohydrodynamic lubrication of rectangular elastomeric seals for linear hydraulic actuators. Proc IMechE, Pt J J Eng Tribol 2003;217(6):461–73; Nikas GK, Sayles RS. Nonlinear elasticity of rectangular elastomeric seals and its effect on elastohydrodynamic numerical analysis. Tribol Int 2004;37(8):651–60] to study rectangular elastomeric seals used in linear hydraulic actuators has been expanded to study the system of two identical seals in a row at some distance from each other (tandem or dual seals). The objective is to evaluate the leakage performance of this particular seal arrangement and possible problems associated with the development of a substantial interseal pressure, which have been observed in some experimental studies. The updated model involves anti-extrusion rings supporting the tandem seals. The present study covers the full typical range of operating conditions of such seals, namely sealed pressure between nearly zero and 35 MPa, stroking velocity between 0.05 and 0.5 m/s, and operating temperature from −54 to +135 °C. The leakage results are in quantitative and qualitative agreement with experimental studies and industrial experience. It is found that the tandem seal arrangement offers a significant reduction of leakage (in the order of 50% or more) compared with the single-seal configuration and that the interseal pressure remains low until the time when it rises abruptly to high value, even exceeding the sealed pressure and risking seal failure. However, by allowing a sufficiently large interseal space, the interseal pressure problem is resolved for the projected service life of the sealing system.