60220 - An Efficient Prediction Method for the Azimuthal Migration of Combustion Inhomogeneity in Multi-Stage Cooled Turbines 

The outlet temperature of combustor is generally monitored by thermocouples at the turbine exhaust. In order to establish the corresponding relationship between the temperature measured by each thermocouple and the working state of each burner, the azimuthal migration of the combustion hot/cold steaks in the multi-stage turbines needs to be quantified. Experiments to measure this migration have high cost and considerable error. It is also difficult to quantify the migration under multiple working conditions. Three-dimensional full-annulus unsteady simulation can obtain this migration. But the simulation of a single working condition could take several weeks, which is too expensive for engineering use.

An efficient prediction method for the azimuthal migration of combustion inhomogeneity in multi-stage cooled turbines is proposed in this paper. This method adds custom variables to the single-passage CFD model of the cooled turbine. By solving the transport equation of the variables, the migration of hot/cold steaks can be predicted by steady-state numerical simulation using the mixing plane at rotor-stator interfaces. The migration computed by this method is compared with the full-annulus unsteady simulation results in multiple design/off-design conditions. The two results are very consistent in the distribution of the migration along the spanwise. The numerical results also agree well with the experimental result under the test condition. However, under certain off-design conditions, the prediction of this method deviates from the result of full-annulus unsteady numerical simulation. Further, the reason of the deviation of this method is discussed. The method proposed in this paper can obtain the azimuthal migration of hot/cold steaks in multi-stage cooled turbines at a low computational cost. It can be applied to the combustion fault diagnosis of gas turbine and precise maintenance of the burners.