**Paper:
Performance mapping of rectangular-rounded hydraulic reciprocating seals
to minimize leakage, frictional work and and abrasive wear with the aid
of a duty parameter****.**

**Author:
****George
K. Nikas **

**Published in: **Tribology International, 2023, 179, 108191

**Abstract**

**Highlights**

- New duty parameter proposed for performance evaluation of rectangular-rounded, reciprocating seals.
- Sealing performance mapping via an objective-function of frictional work and abrasive wear under leakage constraint.
- Full performance mapping in a matter of seconds of the CPU time of a personal computer.
- Performance optimization of a given seal (nullification of leakage per cycle and concurrent minimization of frictional work and abrasive wear).
- Linear relation established between the average film thickness of the sealing contact and the new duty parameter.

**A figure from this
work**

A real rectangular-rounded hydraulic rod seal for reciprocating motion
has been analysed in the article using the author's in-house developed and
experimentally
validated software ROSEAL, which accounts for more than 45 design,
material, dimensional and operating parameters. A parametric study on the
effects of the sealed pressure, the stroking velocity and the edge
(corner) radius of curvature of the seal was conducted with data for about
750 of the aforementioned triplets, such that sealing performance was
thoroughly mapped. The below figure is a contour plot of the mass leakage
per cycle (*Q*_{c}) of the seal for the proposed new duty
parameter *N* (*N*_{in} for instrokes and *N*_{out}
for outstrokes). The dashed boundary separates the green area of zero
leakage from the blue area where there is a leak at the end of every
cycle. The target is to achieve zero leakage without starving the sealing
contact of fluid during instrokes and so without causing increased
abrasion. Optimum values for the duty parameters *N*_{in}
and *N*_{out} for minimizing frictional work and abrasive
wear with the aid of an objective function proposed in the paper have been
established in the analysis as those corresponding to lambda ratio (λ) of
1 and 3, where lambda is the ratio of the average film thickness of the
flat portion of the sealing contact over the composite RMS (root mean
square) roughness. Given those constraints, optimal working conditions are
identified as those corresponding to either point E or F in the figure,
depending on the value of *c*, where *c* 𝜖 [0, 1] is a
weighting coefficient using the previously mentioned objective function to
allow selective prioritization by the researcher to either the frictional
work or the abrasive wear of the seal. In case there are constraints in
the sealing system that preclude operating at either point E or F, a
compromise can be accepted by selecting any point of area EFGA.
Subsequently, having selected optimal values for *N*_{in}
and *N*_{out}, input data corresponding to *N*_{in}
and *N*_{out} can be selected to complete the optimization
process.