Performance prediction and optimization of an industrial centrifugal compressor inlet guide vane system

Variable inlet guide vanes (VIGV) can significantly extend the stable operating range of industrial centrifugal compressors as a result of imparting swirl to the inlet flow. They can typically operate at setting angles ranging from -20 degrees to +80 degrees, and are therefore normally made from flat plate. An undesirable consequence of the large setting angles required by the vanes is a pressure loss leading to a decrease in the overall stage efficiency. An ideal inlet guide vane system will therefore induce large swirl angles in the icier flow with a low associated pressure loss. Efforts have been made to determine the performance characteristics of an existing VIGV design using both an experimental test facility and numerical techniques. The results obtained from these techniques are far more comprehensive than earlier full-scale performance testing. Validation of the performance of the existing design using these techniques has led to the development of a new vane design and potential improvements to the inlet ducting geometry. The test techniques and resulting analyses of the existing design are presented here along with some analyses and predictions of the performance of the improved VIGV system design.