Performance prediction of an industrial centrifugal compressor inlet guidevane system

Variable inlet guide vanes (VIGVs) can significantly extend the stable oper ating range of industrial centrifugal compressors as a result of imparting swirl to the inlet flow. Typical setting angles range from -20 degrees to 80 degrees; therefore the vanes are normally made from flat plate. An undes irable consequence of the large setting angles required by the vanes is a p ressure loss, leading to a decrease in the overall stage efficiency. An ide al inlet guide vane system will therefore induce large swirl angles in the inlet flow with a low associated pressure loss. Efforts have been made to determine the performance characteristics of an e xisting VIGV design using both an experimental test facility and numerical techniques. The results obtained from these techniques are far more compreh ensive than earlier full-scale performance testing. Validation of the perfo rmance of the existing design using these techniques has led to the develop ment of a new vane design and potential improvements to the inlet ducting g eometry. The test techniques and resulting analyses of the existing design are prese nted here together with some analyses and predictions of the performance of the improved VIGV system design.