Entropy generation analysis – the subject of the study described in this two-part feature – is a potential analytical technique that is being developed to provide a useful way of enhancing the functionality of labyrinth seals and perfecting their structure. Compared with conventional techniques, the approach aims to provide a more fundamental analysis of the energy dissipation phenomenon in labyrinth seals and a quantitative description of the amount of energy lost in various flow regions.
Entropy generation analysis – the subject of the study described in this feature – is a potential analytical technique that is being developed to provide a useful way of enhancing the functionality of labyrinth seals and perfecting their structure. Compared with conventional techniques, the approach aims to provide a more fundamental analysis of the energy dissipation phenomenon in labyrinth seals and a quantitative description of the amount of energy lost in various flow regions. The first part of this article, which appears here, mainly looks at the approach and numerical results of the associated research. The second instalment, which will appear in a forthcoming issue of Sealing Technology, will continue coverage by explaining how the technique may be applied.
This article provides details of an analytical study that simulates the characteristics and features of the Rieber joint system, applied to buried pipes made from polyvinyl chloride (PVC). The aim of the research described is to ensure that municipal distribution lines are sealed effectively in the long term, whilst making it easier for crews working in the field to join pipes. Excellent correlation is obtained between computer-based simulation and actual testing of PVC pipe assemblies involving the Rieber gasket.
As simple, small, low-friction and low-cost sealing elements, O-rings are widely used in various types of pumps. When a pump's inner pressure increases, the risk of O-ring failure rises concurrently. The numerical calculations discussed in this article have been done to analyse the mode and root cause of the failure of an O-ring that is installed in a high-lift pump. A novel dual-sealing ring design is also described. The first part of this article, which appears here, mainly describes the computational approach and failure cause analysis based on numerical results. The second instalment will be published in Sealing Technology, Issue 8, Volume 2022.
Advanced rotor–stator seals are becoming more and more common in the latest generation of jet engines. In order to develop new radial seals and fully understand existing ones, testing needs to be done under full-scale conditions. It is necessary to be able to evaluate a new seal concept at “scale one”, under representative operating temperatures, pressure and rotational speed. This article – published in two instalments – presents details of an advanced new test-rig that is able to achieve this goal. It describes many facets of its design, construction, commissioning and use, and the challenges associated with its development.
In the USA, energy technology and oil-field services company Baker Hughes Co has improved the reliability and efficiency of its subsea control system by using technology developed by Greene, Tweed & Co Inc. As this focus article explains, the use of the company's Seal-Connect and electrical harness assembly protects against contamination and interference, and simplifies maintenance.
PUB, Singapore's National Water Agency, has adopted acoustic leak detection tools that are able to “listen” and pinpoint developing leaks in underground water pipes, to minimise water loss, as this brief focus article explains.
The impeller sealing ring in a pump is a critical component that plays an important role in reducing inner flow leakage. The nature of its design is closely related to the volumetric efficiency of the pump. This article provides details of a novel “J-shaped” impeller sealing ring design – in which the clearance length is extended through the use of a special bended structure – and explains its operating principles using fluid mechanics. In addition, a commercial double-suction split-case centrifugal pump is used to validate the new design scheme, and contractive computation results show that it offers a significant advantage in terms of volumetric efficiency, compared with conventional “L-shaped” structures. This work may provide a new, promising impeller sealing ring structure that has broad application in pumps. The first part of this article, which appears here, mainly describes background to the work, and the scheme and principles of the design. The second instalment will be published in the June 2021 issue of Sealing Technology.
Henkel Adhesive Technologies and Analyticon Instruments GmbH have developed a special measuring system for a mobile XRF spectrometer to boost process efficiency at an agricultural machinery parts manufacturer based in Germany. As this article explains, it enables metal coatings to be analysed rapidly.
This article provides details of an experimental study that was carried out to analyse the intrinsic and combined effects of applying surface texturing and a diamond coating to mechanical seals. It explains how these methods enhance seal performance – especially under extreme operating conditions. In order to achieve this, the work involved experimentally comparing, in terms of friction torque and the leakage rate, the performance of textured mechanical seals, and textured and diamond-coated faces, with corresponding components that were untreated.
This article discusses various types of gaskets and allied technology that are used in the nuclear industry in France. After initially covering spiral-wound gaskets, with asbestos winding as the sealing element, it looks at what are referred to as “Graphite Expanse Matrice” gaskets, and their sealing characteristics. In addition, it also explains how calculations for metal-to-metal contact gaskets are done in accordance with the RCC-M® nuclear code, the French standard for the design and construction of pressurised equipment relating to the nuclear island of pressurised water reactor power plants. It concludes with a summary of the types, power-ratings and location of pressurised water reactor facilities in France that are in use or under construction.
This brief focus article explains how the use of a specially developed fibre-reinforced material – trademarked by Metflex Precision Moulding, which is part of Freudenberg Sealing Technologies (FST) – helps prevent system leaks in gas meters and regulators employed in the natural gas industry.
Material-specific modelling is typically employed to analyse components subject to multi-axial loading that are used in engineered systems and structures. To identify the parameters of the model, different tests are used, but these can be both time consuming and costly. Researchers Dr.-Ing. Vladimir Kolupaev, M.Sc. Alok R. Mehta and Dipl.-Ing. (FH) Axel Nierbauer at Germany's Fraunhofer Institute for Structural Durability and System Reliability LBF have developed an efficient method for determining when – in addition to the use of tensile tests – compression tests are necessary, as this article briefly explains.
Trelleborg Sealing Solutions has developed what is described as a unique elastomer material that is compliant with all major global food regulations and standards. Here we briefly look at this versatile material which, according to the company, is suitable for use in a wide range of applications.
