The secondary air flow system of a gas turbine performs the cooling and sealing applications in those parts of the turbine which would otherwise be exposed to the high temperatures resulting in their life reduction or even failures. Accurate analysis of the secondary system is therefore necessary to ensure the safe design of the engine and accurate life predictions. The secondary system is analyzed through the flow network analysis which comprises of chambers or cavities connected through flow passages or restrictions (e.g. seals). The narrow flow channels form a majority of these passages especially in the turbine blades cooling system.
This paper provides a detailed formulation of a one-dimensional model for steady, compressible flow inside a channel which is based on the solution of two equations for a coupled system of mass, momentum and energy equations. The model is applicable over a wide range of subsonic to supersonic flow conditions. It has been validated for the choked flow situation and also has the capability to capture normal shocks. Hence, this model provides a fast, accurate and robust channel simulation technique that is compatible with a complex network analysis.
