Performance Analysis of a Turbine Stage Having Cooled Nozzle Blades With Trailing Edge Ejection

Abstract

This work presents an aerothermodynamic modeling of a cooled turbine blade and the performance analysis of a turbine stage having cooled nozzle blades with trailing edge coolant ejection. A mean line analysis, based on the well-known Ainley-Mathieson scheme, is adopted for the basic loss prediction of the blade rows without cooling. A unique model regarding the interaction between coolant and main gas is proposed. The interactions considered are the heat transfer from main gas to coolant and the temperature and pressure losses by the mixing of two streams due to the trailing edge coolant ejection. For a model turbine stage with nozzle cooling, parametric analyses are carried out to investigate the effect of main design variables (amount of coolant flow, coolant temperature and coolant ejection area) on the stage performance. The influences of coolant mass flow ratio and temperature on the mixing loss and specific work are investigated. The results are also rearranged to investigate the effect of blade temperature on the specific work. Analysis is also carried out by varying the ejection area, which may give useful criteria in determining the coolant condition and ejection hole size of real gas turbine engines.