Performance Characterization of Turboshaft Engines: Work Potential and Second-Law Analysis

This paper develops and describes work potential analysis methods applicable to turboshaft engine flow-fields. These methods are based on the second-law of thermodynamics and enable a unified, comprehensive assessment of performance at the part, component, and engine levels. The focus herein is on using gas specific power as a work potential figure of merit in analyzing turboshaft engines. This is shown to be a useful tool for assessing local performance potential in a gas turbine flow-field. The fundamental relationships between heat, work, and irreversibility in turboshaft engines are developed and the relationship of flow irreversibility to engine performance losses is discussed. These theoretical ideas are then formulated in a method that enables characterization of performance losses in terms of engine spatial location and loss mechanism. This method is then demonstrated at the engine system level via cycle analysis, at the component level via quasi 1-D analysis, and at the part level via a stator row multi-dimensional CFD simulation analyzed in terms of irreversible entropy production.