Gas Turbine engine components like Combustor, Diffuser, and Turbines are subjected to very high temperatures. Predicting accurate temperatures of such components demand accurate Radiation modeling along with Conduction and Convection. Radiation heat transfer modeling is very complex due to non linear dependence on temperature and additional parameters driving the heat transfer like shape factor, emissivity, surface area and absorbtivity of material.
The commercial software ANSYS developed various Radiation techniques like ‘Radiation Matrix’, ‘Radiosity’ and ‘Radiation modeling between a surface and a point’. A detailed study has been carried out to compare different Radiation models. The ease of building the model, computational time, accuracy, and limitations are thoroughly examined. It is found that all existing methods have some limitations in accuracy, computational time or system requirements.
To overcome some of these limitations, a new technique called ‘Surface Effect Element Method’ is proposed in this paper. This method uses ‘Radiosity’ for the shape factor computation and ‘Radiation modeling between a surface and a point’ for modeling Radiation between two surfaces. The average of one surface temperature is transferred to a single point which in turn is used to model the Radiation to the second surface and the same procedure is repeated for the second surface too.
A detailed study is carried out and the proposed technique is compared against the available methods. The new technique enables accurate computation of transient temperatures for gas turbine components leading to accurate life prediction for these components. It is shown that ‘Surface Effect Element Method’ has comparable accuracy but significantly lower cycle time and efforts compared to existing methods.
Transient thermal stresses and thermal deformations of a semi-infinite solid cylinder with heated moving end surface. Effect of heat transfer on the end surface.
