Contact deformation of the pipeline sealing unit

Authors

Keywords:

turbine, pipeline, flange connection, contact problem, stress-strain state, contact

Abstract

The features of the turbine steam line sealing unit stress-strain state are examined on the basis of the usage of a three-dimensional design model of the construction and contacting surfaces. The considered unit consists of the pipeline, a crimp casing consisting of two halves with an outlet in one of them, and a gasket. A mathematical model that takes into account the mechanical loads caused both by the internal steam pressure on the steam line wall and by the casing fasteners tightening has been formed. This model also includes contact interaction in the sealing unit on the contact surface of the pipeline, the upper and lower halves of the casing. This contact problem solving method, based on the application of the finite element method, is proposed. The finite element model is based on twenty-unit three-dimensional finite elements with three degrees of freedom at each unit. Eight-unit contact finite elements were used to describe contact and sliding between surfaces. Contact conditions are taken into account with the penalty method usage. The verification of the model and the software that implements the proposed method is carried out by comparing the calculation results and experimental data obtained on the physical model of the pipeline. The physical model was made from a low-modulus material with full geometric similarity and the same ratio of the elastic moduli of materials as in a real object. The stress-strain state of the sealing unit of a real pipeline in a three-dimensional setting was determined and the most stressed zones in the unit, which require increased attention during the design and operation of pipelines and their connections, were identified. The developed approach and software make it possible to determine the contact pressure for the horizontal joint flanges of highly stressed cylinder bodies of powerful steam turbines, which helps to avoid a large number of expensive experimental studies.

Author Biography

Andrii O. Kostikov, A. Pidhornyi Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi St., Kharkiv, 61046, Ukraine)

Associate Member of NASU

References

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Published

2021-01-10

Issue

Vol. 23 No. 4 (2020)

Section

Power Engineering

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Copyright (c) 2021 Serhii A. Palkov, Andrii O. Kostikov

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