In this paper, a 3D model of a gas turbine used in a single-stage turbojet engine, including stator and rotor, is considered for structural and thermal analysis. A modified conjugate heat transfer (CHT) method is used in a developed computer code to predict heat flux and the coupled non-adiabatic external flow field and temperature field on the blades. The thermo-elastic behavior of one blade made of Rene’ 80H is studied by the finite element method, where the temperature distribution, and the thermal and centrifugal stresses are calculated. Thermal stresses are studied for the materials with temperature-dependent properties and are compared to those with constant material parameters, E (T), α (T) and K (T). To have a complete CHT procedure, a unique consideration is utilized to link the boundary conditions. To verify the CHT method and temperature distribution on the blade, an experimental study is carried out during a metallographic study in the laboratory. A scanning electron microscopy is used to observe microstructures in different sections of the target blade. The precipitation of the blade carbides and grain type and size characterization are discussed to verify the results. The results indicate (through the size of γ′ and MC type) an increased temperature in different levels of a blade from root to tip. The alloy deterioration mostly occurs in the critical areas where blade’s mechanical properties decrease considerably.

SEM Gamma Prime Observation in a Thermal and Stress Analysis of a First-stage Rene’ 80H gas Turbine Blade: Numerical and Experimental Investigation

Effect of pyrometer type and wavelength selection on temperature measurement errors for turbine blades

This article developed an analytical two-color thermometry model combined with a mathematical radiative heat transfer model. The proposed model was used to investigate the performance of two-color pyrometry affected by absorption bands in hot combustion gases. This model was validated by comparing with a range of measured data and the results of other numerical solutions. The analysis of the temperature errors produced by a high-temperature H2O–CO2–N2 mixture in three measurement situations was presented. The presence of the high-temperature H2O–CO2–N2 mixture greatly affected the measurement accuracy of two-color pyrometry. Minimizing the absorption and emission effects by selection of the instrument spectral band is useful when interfering combustion gases are at low concentrations. The results showed that the measured temperature had an apparent oscillatory phenomenon due to combustion gases’ absorption and emission effects. This phenomenon tended to further strengthen with a thicker hot interfering ga...

Quantifying the Effects of Combustion Gases’ Radiation on Surface Temperature Measurements Using Two-Color Pyrometry

Accurate measurement of turbine blades temperature is of great significance to ensure the safe operation of the engine. The temperature measurement of turbine blades is generally carried out by radiation temperature measurement method, but due to the particularity of the working environment of turbine blades, the temperature measurement results will be greatly affected. In various research applications, it has been pointed out that environmental influences may cause errors in blade radiation temperature measurement. Influencing factors include the reflection effect of adjacent hot end components, the radiation and absorption effect of high temperature gas, and the errors introduced in the process of radiation temperature measurement data processing and calculation. In this paper, the radiation temperature measurement methods of engine turbine blades have been discussed. On this basis, the influence of turbine blade radiation temperature and its elimination methods are summarized. 

Review: radiation temperature measurement methods for engine turbine blades and environment influence

https://iopscience.iop.org/article/10.1088/1361-6501/aab394/pdf

Ketui Daniel Kipngetich

Papers

Reflection error correction of gas turbine blade temperature

Analyzing the influence of combustion gas on a gas turbine by radiation thermometry