Abstract
A mean-line compressor performance calculation method is presented that covers the entire operating range, including the choked region of the map. It can be directly integrated into overall engine performance models, as it is developed in the same simulation environment. The code materializing the model can inherit the same interfaces, fluid models, and solvers, as the engine cycle model, allowing consistent, transparent, and robust simulations. In order to deal with convergence problems when the compressor operates close to or within the choked operation region, an approach to model choking conditions at blade row and overall compressor level is proposed. The choked portion of the compressor characteristics map is thus numerically established, allowing full knowledge and handling of inter-stage flow conditions. Such choking modelling capabilities are illustrated, for the first time in the open literature, for the case of multi-stage compressors. Integration capabilities of the 1D code within an overall engine model are demonstrated through steady state and transient simulations of a contemporary turbofan layout. Advantages offered by this approach are discussed, while comparison of using alternative approaches for representing compressor performance in overall engine models is discussed.
Highlights
Development of gas turbine engines is a highly iterative procedure that involves different disciplines [1]
BRM models any type of blade row [rotor, stator, inlet guide vanes (IGVs), of variable or fixed geometry] and establishes the row outlet conditions by solving iteratively the set of equations formed by mass and gas composition continuity, the conservation of energy, and loss and deviation correlations introduced to calculate the flow across the row
The component was operated in both 0D and 1D mode for two values of NcRdes; one which is present in the map data (95%) and one that is between existing values (96.3%)
Summary
Development of gas turbine engines is a highly iterative procedure that involves different disciplines [1]. They formulated a bisection method for solving the system of mean-line equations at subsonic, supersonic, and choke conditions They described a modelling approach for extending the choked portion of the map characteristics where they increased the losses of the duct following a choked blade row, until the last row or the compressor exit chokes. The Mean-Line Code for performance analysis of axial-flow, multi-row compressors, was developed and validated in the same environment as the conventional 0D components for turbomachinery performance simulations, used to build overall engine models. BRM models any type of blade row [rotor, stator, inlet guide vanes (IGVs), of variable or fixed geometry] and establishes the row outlet conditions by solving iteratively the set of equations formed by mass and gas composition continuity, the conservation of energy, and loss and deviation correlations introduced to calculate the flow across the row. The magnitude of differences of the results using the two approaches will be presented in the results section
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