Original scientific paper

https://doi.org/10.19279/TVZ.PD.2021-9-3-11

DESIGN AND FABRICATION OF OPTIMISED AEROSTATIC DRY GAS SEALS USING ADVANCED NUMERICAL MODELS AND NEXT GENERATION PRODUCTION TECHNOLOGY

Schaham Schoar ; University of Duisburg-Essen, Chair of Turbomachinery, Duisburg, Germany
Arno Elspaß ; University of Duisburg-Essen, Chair of Manufacturing Technology, Duisburg, Germany
Hans Josef Dohmen ; University of Duisburg-Essen, Chair of Turbomachinery, Duisburg, Germany
Stefan Kleszczynski ; University of Duisburg-Essen, Chair of Manufacturing Technology, Duisburg, Germany
Friedrich-Karl Benra ; University of Duisburg-Essen, Chair of Turbomachinery, Duisburg, Germany

Abstract

To avoid pollution of the environment, it is necessary to separate the oil of the oil- lubricated bearings of a turbomachine from the atmosphere. For this purpose, gas driven sealing systems which operate with a non- toxic gas are used. These sealing systems must be robust and reliable but also should have a low consumption of the operating gas to meet economic criteria. Furthermore, the seals should be tight without any operating medium when the turbomachine is at a standstill “blocked situation”. All these requirements are combined in the so- called aerostatic seals which are used in the industry already. The robust aerostatic seals are manufactured conventionally by drilling a defined number of holes with fixed diameter in the seal sliding ring to ensure the permeability. The characteristic of the seals can be influenced in a certain spectrum by varying the number and the diameter of the holes. This effect has already been demonstrated by Gerke (1991), Schulz (1999) or Dormann (2002), among others. Actually, the possibilities of conventional manufacturing processes restrict the use of the complete potential of such seal types. An approach to increase the performance of this seals is the application of Additive Manufacturing (AM) processes directly during the design. It is widely accepted, that AM processes offer a great potential in terms of geometrical freedom and thus for optimised functionality. One of the main advantages of these AM processes is that exposure strategies which contain the typic process parameters can be set for each part separately. Furthermore, the technic offers a great potential for production of filigree structures. With these structures it is possible to manufacture a seal with the necessary permeability as well as dense material which serves as a mounting device.As shown in a previous publication from Schoar et al. (2019), a numerical model which is required to support the design process of seals with undefined as well as defined distributed permeabilities has been derived and validated using a test bench. In this work, the AM process of laser-based powder bed fusion of metals is used to generate coaxial gas seals with defined permeability distributions according to the calculations of the numerical model. It is shown that the fabrication of AM dry gas seals with the required permeability distributions is possible. A comprehension of the results from the numerical model and the experiment proves, that the validated numerical model can be used for the design of seals with different permeabilities and thus for the aerostatic dry gas seals (ADGS).

Keywords

ADDITIVE MANUFACTURING; PBF- LB/M; STATIC SEAL; DRY GAS SEAL

Hrčak ID:

273773

URI

https://hrcak.srce.hr/273773

Publication date:

10.11.2021.

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