Turbine Blade Static Strength assessment
Nonlinear static strength analysis of the cooled turbine blade was performed.
Finite element model (FEM) was performed based on finilized 3D CAD design. Mesh model consists of 3D hexahedral and tetrahedral elements. FEM was refined in regions with stress concentration (blade root section and fillets).
Both materials have stress-strain nonlinearity and changes in yield and ultimate stress area were taken into account.
Turbine blade alloy have yield stress at 490 MPa and ultimate stress at 605 MPa for maximum operatiing temperature 1100 deg C. Variation of material Young's modulus due to temperature was also taken in account.
In temperature range 750-900 deg C abnormaly mechanical properties observed. Yield and tesile strength a bit increase untill temperature reaches 900 deg C and only then decrease.
Turbine blade investigated according to three main types of load:
All these loads were taken into account in analysis preparation.
Aerodynamic load distribuded on the blade profile.
Equal pressure drop on the blade profile is about 0.5 MPa.
Working speed of the turbine is 3000 rpm.
Blade temperature is in range 500 - 1100 deg C.
In the results stress and deformation levels were determined and investigated. Figures with stress and displacement diagram are shown in the left.
Maximum radial displacement is approx. 4.2 mm.
Small are of plastic strain occures near contact reagions.
Maximum stresses in root section of the blade are not exceed limitation.