Loss Characterisation of a Variable Inlet Guide Vane Configuration with Split Blades and Centrepiece

Authors

Roman Gawin Frank  - University of the Bundeswehr Munich, Germany
Christian Wacker - MAN Energy Solutions, Germany
Dragan Kožulovic - University of the Bundeswehr Munich, Germany
Reinhard Niehuis - University of the Bundeswehr Munich, Germany

Abstract

Throughout the past decades, remarkable efforts have been made to improve the part load operation of compressors by a broadened, more efficient working range of the variable inlet guide vane (VIGV). The main focus has been put on the development of advanced blade geometries. Especially adjustable blades with an independent front and tail blade segment proved to be particularly promising. Potential benefits of an implemented centrepiece, which is not self-evident in many industrial compressor applications, has often been neglected, in turn. Avoided blade tip vortices and a lower tendency of open flow separation by higher, minimum local Reynolds numbers nevertheless promise a significant advantage of the hub. To prove whether these advantages outweigh detriments such as losses induced by the hub struts and additional wall-blade interactions, the performance of two VIGV configurations with and without centrepiece are juxtaposed in the following. The experimental comparison was carried out by five-hole probe wake field traverses and oil film visualizations. The influence of recent blade developments is furthermore considered by the investigation of a customary, symmetric blade and a modern split blade geometry. The latter configuration was proposed by Händel et al. [1] and firstly integrated in an annular cascade by Frank et al. [2]. It is based on a variable front and rear blade segment, which enables an independent adjustment of the camber line at varied stagger angles. The measurements of the configurations with and without integrated hub and the two blade geometries were performed along the full low loss working range of the VIGV between stagger angles of 40 and 90_. The experiments were conducted at the VIGV test facility of the University of the Bundeswehr Munich [3]. Details regarding the benefits of an integrated centrepiece and its potential synergies with a split blade will be outlined in the proposed paper. Bibliography [1] Händel, D., Niehuis, R., and Klausmann, J., 2015. “Aerodynamic Investigation of an Advanced VIGV Design of Adjustable Geometry for Very High Flow Turning”. GT2015-42166, ASME Turbo Expo. [2] Frank, R. G., Wacker, C., and Niehuis, R., 2021. “Loss Characterization of a Conventional Variable Inlet Guide Vane”. Int. J. Turbomach. Propuls. Power, 6(30). [3] Frank, R. G., Wacker, C., and Niehuis, R., 2020. “A New Test Facility for Advanced Testing of Variable Inlet Guide Vanes”. MTT2520A18, MTT Measuring Techniques in Turbomachinery.