The preliminary design of multistage axial compressors in gas turbine engines is typically accomplished with mean-line methods. These methods, which rely on empirical correlations, estimate compressor performance well near the design point, but may become less reliable off-design. For land-based applications of gas turbine engines, off-design performance estimates are becoming increasingly important, as turbine plant operators desire peaking or load-following capabilities and hot-day operability. The current work develops a one-dimensional stage stacking procedure. This includes a newly-defined blockage term, which is used to estimate the off-design performance and operability range of a 13-stage axial compressor. The new blockage term is defined to give mathematical closure on static pressure, and values of blockage are shown to collapse to a curve as functions of stage inlet flow coefficient and corrected speed. Utility of the stage stacking procedure is demonstrated by estimation of the minimum corrected speed which allows stable operation of the compressor. Further utility of the stage stacking procedure is demonstrated with a bleed sensitivity study, which estimates a bleed schedule to expand the compressor’s operating range.
Development and Applications of a Stage Stacking Procedure