Compressor Modeling and Simulation Using Object-Oriented Turbomachinery Analysis Code (OTAC)

Abstract

The objective of this research is to investigate the capabilities of OTAC as a compressor modeling tool suitable for conceptual design in an academic research environment. The investigation was carried out by modeling two multi-stage compressor models, the NACA 5-stage transonic compressor and the GE E3 high pressure compressor. For these models the Aungier compressor loss and deviation model was coded in several OTAC sub-elements.The NACA compressor, being very similar in design to the empirical data base used in the Aungier loss model, provided an excellent demonstration of the model capability. The effect of increasing the number of streamlines was observed generally to improve the accuracy of the loss prediction and the shape of the speedline characteristics.The E3 HPC, having numerous stages made up of more modern airfoil designs, required additional adjustment to the loss model. A process for identifying and adjusting several tuning factors was demonstrated. It was found that separating the loss matching from the velocity triangle matching facilitated the process. To accomplish this, the design point was first matched in "calibration mode", whereby the OTAC solver setup was modified to match the tangential velocities provided in the E3 design report which did not satisfy the simple radial equilibrium assumption of OTAC.While much work still remains to be done, this preliminary investigation has demonstrated that OTAC may be a useful teaching tool, bridging the gap between introductory engine cycle analysis courses and advanced turbomachinery analysis courses. The capability of the model also appears suitable for serious conceptual design applications within an integrated multidisciplinary design environment.