Cooling Air Flow Characteristics in Gas Turbine Components

Abstract

An analytical model for the prediction of cooling air flow characteristics (mass flow rate and internal pressure distribution) in gas turbine components is discussed. The model addresses a number of basic flow elements typical to gas turbine components such as orifices, frictional passages, labyrinth seals, etc. Static bench test measurements of the flow characteristics were in good agreement with the analysis. For the turbine blade, the concept of equivalent pressure ratio is introduced and shown to be useful for predicting (i) the cooling air flow rate through the rotor blade at engine conditions from the static rig and (ii) cooling air leakage rate at the rotor serration at engine conditions. This method shows excellent agreement with a detailed analytical model at various rotor speeds. A flow calibration procedure preserving flow similarity for blades and rotor assemblies is recommended.