Search

A review of existing research on signatures of gas turbine faults is presented. Faults that influence the aerothermodynamic performance of compressors and turbines, such as fouling, tip clearance increase, erosion, variable geometry system malfunction, and object impact damage, are covered. The signatures of such faults, which are necessary for establishing efficient gas path diagnostic methods, are studied. They are expressed through mass flow capacity and efficiency deviations. The key characteristics of the ratio of such deviations are investigated in terms of knowledge existing in published research. Research based on experimental studies, field data, and results of detailed fluid dynamic computations that exist today is found to provide such information. It is shown that although such signatures may be believed to have a unique correspondence to the type of component fault, this is only true when a particular engine and fault type are considered. The choice of diagnostic methods by developers should, thus, be guided by such considerations instead of using values taken from the literature without considering the features of the problem at hand. [ABSTRACT FROM AUTHOR]

An approach for preliminary aero-engine design, incorporating a mean-line code for the design of axial-flow, multi-stage compressors, is presented. The compressor mean-line code is developed and integrated within a framework for the preliminary design and assessment of aero-engine concepts. It is then combined with modules for compressor map generation, multi-point engine design, steady-state and transient engine off-design performance and aircraft mission analysis. Implementation examples are presented, demonstrating the determination of the optimal combination of compressor and engine design parameters for achieving minimum fuel burn over a specific aircraft mission, while obeying constraints that guarantee operability over the entire flight envelope. Constraints related to compressor stability during transient maneuvers between idle and static take-off conditions and engine temperature limits at maximum take-off are respected by the final design. The results demonstrate the potential for design trade-offs between engine performance at the aircraft mission level and compressor aerodynamic stability. [ABSTRACT FROM AUTHOR]

Disks in gas turbines are optimized for minimum weight, while satisfying both geometry and stress constraints, in order to minimize the engine production, operation, and maintenance costs. In the present paper, a tool is described for the preliminary mechanical design of gas turbine disks. A novel formulation is presented, where the disk weight minimization is achieved by maximizing the stresses developed in the disk. The latter are expressed in the form of appropriately defined design and burst margins. The computational capabilities of the tool developed are demonstrated through comparisons to calculations with a higher fidelity tool. The importance of accurately calculating thermal stresses is demonstrated and the ability of the tool for such calculations is discussed. The potential and efficiency of the tool are illustrated through a proposed re-design of the disks of a well-documented ten-stage compressor. Finally, the integration of the tool into an overall engine design framework is discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]