Novel Test Facility for Investigation of the Impact of Thermally Induced Stress Gradients on Fatigue Life of Cooled Gas Turbine Components
| Autor: | Kathrin A. Fischer, Marcus Thiele, Uwe Gampe |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Gas turbines
Materials science Test facility 010308 nuclear & particles physics Nuclear engineering Mechanical Engineering Energy Engineering and Power Technology Aerospace Engineering 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Stress (mechanics) Temperature gradient 020303 mechanical engineering & transports Radiant heating Induced stress Fuel Technology 0203 mechanical engineering Heat flux Nuclear Energy and Engineering 0103 physical sciences 0210 nano-technology 010306 general physics Turbocharger |
| Zdroj: | Journal of Engineering for Gas Turbines and Power. 141 |
| ISSN: | 1528-8919 0742-4795 |
| Popis: | A novel test facility has been designed and set up for the investigation of the influence of stationary temperature, and thus thermally induced stress gradients with respect to the damage evolution of cooled gas turbine components. Thermally induced stress gradients differ from geometrically induced stress gradients. From the point of view of stress mechanics, they are independent from external loads. From the perspective of material mechanics, their impact on service life is influenced by locally different material properties and strength. However, the impact of thermally induced stress gradients on the cyclic life of high loaded, cooled components is not precisely known. In order to increase knowledge surrounding these mechanisms, a research project was launched. To achieve high temperature gradients and extended mechanical stress gradients, large heat fluxes are required. The authors developed a test bench with a unique radiant heating to achieve very high heat fluxes of q̇ ≥ 1.6MW/m2 on cylindrical specimen. Special emphasis has been placed on homogenous temperature and loading conditions in order to achieve valid test results comparable to standard low cycle or thermo-mechanical fatigue tests. Different test concepts of the literature were reviewed and the superior performance of the new test rig concept was demonstrated. The austenitic stainless steel 316L was chosen as the model material for commissioning and validation of the test facility. The investigation of thermally induced stress gradients and, based on this analysis, low-cycle fatigue tests with superimposed temperature gradients were conducted. Linear elastic finite element studies were performed to calculate the local stress-strain field and the service life of the test specimens. The test results show a considerable influence of the temperature gradient on the low-cycle fatigue life of the investigated material. Both the temperature variation over the specimen wall and thermally induced stresses are stated to be the main drivers for the change in low-cycle fatigue life. The test results increase the understanding of fatigue damage mechanisms under local unsteady conditions and can serve as a basis for improved lifetime calculation methods. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|