Investigation of the stress-strain state of a turbine blade twisted according to the potential vortex law by the finite element method

Increase of power and complication of turbomachinery design is accompanied by stricter requirements to their reliability. Increasing the service life of turbomachinery is also one of the main tasks of quality improvement. Since the blade is a highly loaded element of any turbomachine, high operational requirements are imposed on it, expressed in reliability and durability of this element. A large number of factors affect the performance of the blade, one of which is its twist. The purpose of the current study is to determine the effect of twist of a gas turbine blade twisted according to the potential vortex law.

The results of research of twist law influence on stress-strain state of the blade of the last stage of axial gas turbine, twisted according to the potential vortex laware presented. For this purpose, using the internal packages Ansys, CFX and Static Structural, we performed an interdisciplinary conjugate analysis of the solutions of the computational gas dynamics and static strength problems. During the analysis of the static strength problem we considered the tensile stresses arising in the field of centrifugal forces, bending stress (in different planes — from the pressure difference between inlet and outlet and from the pressure difference on the concave and convex surfaces of the blade), torsional stress, as well as thermal stress.

Evaluation of the obtained results in conjunction with the analysis of previously derived analytical dependencies allowed to establish the influence of blade twist on the stress-strain state. The factor of torsion stresses and deformations should be taken into account when designing twisted blades and their subsequent gas-dynamic and strength estimation.

1. “Computational analysis of a gas turbine blade with different materials,” Singh H. P., Rawat A., Manral A. R., and Kumar P., Mater. Today Proc., vol. 44, pp. 63 – 69, 2021, doi: 10.1016/J.MATPR.2020.06.486.

2. “Structural analysis of gas turbine blades made of Mo-Si-B under transient thermo-mechanical loads,” Kauss O., H. Tsybenko H., Naumenko K., Hütter S., and Krüger M., Comput. Mater. Sci., vol. 165, pp. 129 – 136, Jul. 2019, doi: 10.1016/J.COMMATSCI.2019.04.023.

3. “Thermomechanical stress analysis for gas turbine blade with cooling structures,” Tong F., Gou W., Li L., Gao W., and Feng Yue Z., Multidiscip. Model. Mater. Struct., vol. 14, no. 4, pp. 722–734, Oct. 2018, doi: 10.1108/MMMS-08-2017-0081.

4. Ilchenko B. V., Gizatullin R. Z., Yarullin R. R., "Analysis of stress and strain state of blades of turbine k-210-130: Proceedings of Akademenergo, pp. 74 – 81, 2011, Accessed: Apr. 28, 2022. [Online]. Available: https://eds.s.ebscohost.com/eds/detail/detail?vid=0&sid=bb5bbebb-0618-4da2-afe0-4e6402d80030%40redis&bdata=Jmxhbmc9cnUmc2l0ZT1lZHMtbGl2ZQ%3D%3D#AN=edselr.16910324&db=edselr