Simulation and analysis of creep and fatigue of gas turbine blades

The increasing use of gas turbines in the industry has attracted the attention of researchers to improve the performance and increase the reliability of its components. Turbine blades are one of the most basic and valuable components of turbines and are subject to unpredictable deterioration and failure due to complex stress and heat conditions. These sudden failures can damage other parts of the turbine by causing damage to the production circuit. In addition, replacing these blades can incur heavy costs for power plants. For this reason, the analysis of creep and fatigue of gas turbine blades with the help of CAE software is very important.

gas-turbine-failure

gas-turbine-failure

The makers and users of the blades are always trying to determine the useful life of the parts and to repair or replace them in due time. Therefore, the main issue in estimating the life of industrial parts is always to increase efficiency and productivity and increase profits and reduce financial losses. In this regard, finite element numerical simulation (FEA) and computational fluid dynamics (CFD) software play a colorful role in analyzing the creep and fatigue of gas turbine blades.

Movable gas turbine blades are one of the most sensitive parts of the turbine. Because they are subjected to high temperature and stress loads during service. Movable blades are affected by factors such as fatigue and creep. These factors limit their lifespan and should be taken into consideration when designing, building and inspecting gas turbines. Estimating the life of these components is essential to prevent the sudden failure of moving vanes during operation and, consequently, to prevent severe damage to the gas turbine assembly.

The hot gases around the peroxide are oxidizing and contain destructive substances such as sulfate and chloride. These materials are both corrosive and wear due to their high speed. Under combined loading conditions, at high temperatures and periodic loading, creep and fatigue effects are seen in the components. Creep and fatigue will damage and reduce the properties of the material and ultimately shorten the life of the parts. Using the creep and fatigue analysis of gas turbine blades, we can have a better understanding of the mechanical behavior of gas turbine blades in their operating conditions.

fatigue-creep-cfd-fem-abaqus-ansys-gas-turbine

fatigue-creep-cfd-fem-abaqus-ansys-gas-turbine

Methods for estimating the life of gas turbine blades

In total, three computational methods, non-destructive (NDT) and destructive, are considered and used to analyze the creep and fatigue of gas turbine blades and to estimate their life. Destructive and non-destructive methods are sometimes stated to have higher accuracy than computational methods, but the high costs that these methods incur to the employer make the use of computational methods such as numerical finite element simulations at the top of the method. Has taken into account the estimated life of the blades.

gas-turbine-fracture-fatigue-creep

gas-turbine-fracture-fatigue-creep

Turbine blade failure mechanisms

Numerous breakdown mechanisms are effective in reducing the life of turbine blades. Among them can be

  • Creep
  • Fatigue
  • Corrosion
  • Oxidation and
  • Erosion noted

Therefore, in estimating the life of the blades, all these parameters should be considered as much as possible.

Gas-turbine

Gas-turbine

Creep life prediction models

To predict the creep life of Larsen-Miller, Monkman-Grant, Cole-Castillo, Dobbs-Milica, Manson-Huffred, Sherby-Dern models are the most famous and widely used models available.

Hearts predict life fatigue

Caffeine-Manson, Bern-Stein, Zamrick, Kanasaki, and Russell models are also popular models in the field of fatigue life prediction.

Predicting the creep-mutual fatigue life

In this regard, various models based on the laws of energy conservation and motion size conservation, such as Ling Chen, models based on Goswami viscosity to make a connection between creep data and material fatigue at high temperatures, the gradual evolution model of cheerful damage and many models Others have been developed in recent years.

Hypotheses and questions

In order to simulate and analyze the problems of simulation and analysis of creep and fatigue of gas turbine blades, some basic questions and assumptions need to be asked.

Is the blade cooling? (If not, the blade isothermal assumption in stable operating conditions can be used to determine suitable working and boundary conditions)

  • Perform static analysis to determine the stress distribution in the blade
  • Determining critical areas and sections with the help of static analysis
  • Perform creep analysis to determine the minimum creep strain rate on the blade
  • Determining the fatigue life of the blade by defining the plastic properties of the material, and the rotational speed of the rotor
  • Estimation of life in creep and net fatigue
  • Estimation of creep-reciprocal fatigue life using one of the considered models
  • Have the blades suffered initial corrosion or abrasion?
  • Blade material and the best material models to define it in the software
  • Precise loading conditions

Application of gas turbine in industry

The most important applications of gas turbines in the power plant industry are energy, oil and gas, and aerospace.

Software used:

In designing and analyzing the creep and fatigue of gas turbine blades, the following CAD and CAE software have been used more than other software. However, each company can use similar software according to its work policy and strategy.

Katia software (geometric modeling)
Ionic graphics software (geometric modeling)
ABAQUS (finite element analysis)
ANSYS (finite element analysis)
MSC-Fatigue Life Estimation and Fatigue Analysis
Fe-safe life estimation and analysis

 

If you have any questions about creep and fatigue analysis of gas turbine blades and fixing their defects and shortcomings, you can contact our experts.