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Labyrinth seals design using multi-material topology optimization based on a level set approach

Grant number: 18/21350-3
Support type:Scholarships abroad - Research Internship - Post-doctor
Effective date (Start): March 01, 2019
Effective date (End): February 29, 2020
Field of knowledge:Engineering - Mechanical Engineering
Principal Investigator:Emílio Carlos Nelli Silva
Grantee:Hélio Emmendoerfer Junior
Supervisor abroad: Kurt Maute
Home Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Local de pesquisa : University of Colorado Boulder, United States  
Associated to the scholarship:16/09923-2 - Labyrinth seals design using topology optimization based on a level set approach, BP.PD

Abstract

This work aims to use topology optimization to improve the efficiency of labyrinth seals, which are non-contacting seals used extensively in turbomachinery, from the use of multiple materials. Topology optimization is a computational method to find the best distribution of material in a structure in order to maximize or minimize an objective function. A multi-objective topology optimization problem that considers both fluid and structural areas is proposed. Concerning fluids, the objective is to minimize the leakage flow (or maximize the pressure drop) passing through the seal. Taking into account structural aspects, the focus of this research plan is to deal with the multi-material topology optimization problem with constraints on the von Mises stress field. Within this context, materials with different properties are distributed in the labyrinth seal: stiffer materials are employed in regions with high pressure (inlet) to avoid deformations to the optimized flow path and, consequently, change the leakage, and softer materials are used in regions with lower pressure (outlet). From this latter property in the seal, the concepts of compliant mechanism design are introduced to obtain flexible profiles. Thus, smaller gaps between shaft and seal can be considered bringing improvements as lower leakage levels, the increase of the lifetime of the seal and flexibility of the seal in case of rubbing with the shaft. A level set framework is used to control the (multi-material) solid-fluid design domain. The level set method allows for a clear tracking of boundaries along the optimization process and it does not need post-processing techniques. It is expected that distinct material properties in certain regions of the labyrinth seal may result in increased performance. The fabrication of the resulting optimized geometries is feasible by additive manufacturing technologies, including parts combining many materials.