A stage-by-stage compressor modeling technique for single- and dual-spool compression systems

The objective of this effort was to extend a current one-dimensional, time-dependent, single-spool, stage-by-stage compressor modeling technique to include dual-spool compression systems. Prior to development of the dual-spool capability, a solution to a numerical instability problem which had existed in some previous compressor modeling efforts was developed by reformulating the modeling technique to use MacCormack's explicit differencing scheme and a method of characteristics boundary treatment to solve the set of differential equations. This investigation describes the numerical technique used to provide a more numerically stable model, incorporation of that numerical technique into an existing one-dimensional, single-spool compressor model, and the formulation of a dual-spool compression system model. The dual-spool model was applied to a current compression system and several types of planar destabilizing disturbances were studied to determine their effect on compression system stability. Model predictions were validated against experimental data whenever possible. This extension provides a tool for studying overall compression system and interspool reaction to time-variant planar disturbances and compression system throttling transients.