Remarkable efforts have been made to improve the part load compressor operation by a broadened, more efficient working range of variable inlet guide vanes (VIGVs). Though axial VIGVs with either open blade tips or hub are state of-the-art, a direct comparison of both basic vane designs has hardly been considered. VIGVs with hub promise a more efficient flow deflection by avoided blade tip vortices, an improved radial guidance of the flow, and the shift of stall effects towards lower stagger angles by increased averaged blade Reynolds numbers. At the same time, the hub goes with shortcomings such as the losses induced by the struts and wall-blade interactions at the blade tips. To identify whether the expected advantages outweigh the drawbacks, the performance of two, customary VIGVs with and without hub were juxtaposed. Investigations were carried out by five-hole probe wake field traverses and oil film flow visualisations. The full low loss working range was covered by a sufficient range of investigated stagger angles. Whereas the vane configuration with open blade tips proved superiority at high stagger angles, the vane with hub becomes worthwhile at successively reduced stagger angles. From a fluid mechanical perspective, the hub is hence recommended if a wide load range is frequently requested by the compressor application.    «

Remarkable efforts have been made to improve the part load compressor operation by a broadened, more efficient working range of variable inlet guide vanes (VIGVs). Though axial VIGVs with either open blade tips or hub are state of-the-art, a direct comparison of both basic vane designs has hardly been considered. VIGVs with hub promise a more efficient flow deflection by avoided blade tip vortices, an improved radial guidance of the flow, and the shift of stall effects towards lower stagger angl...    »