Investigations on Design Space for Highly Loaded Tandem Bladed Axial Flow Rotor- novel Stator for Low-speed Compressor Research Facility

Abstract

Tandem bladed axial flow compressor concept has immense potential for increasing the stage loading over conventional stages. This infers significant improvement in gas turbine engine operational economics and performance. However, implementation of tandem configuration invites additional three dimensionalities in the flow field. This complicates the design process limiting the realization of the tandem bladed rotor concept. The present study addresses the strategies for development of a low-speed axial compressor design implementing tandem bladed rotor and single stator. Both the rotor and stator flow mechanisms have been investigated in detail using steady state simulations. A highly loaded tandem bladed rotor is followed by single bladed stator which handles the highly swirled flow. The single blade configuration of stator results in higher diffusion factor which is more susceptible to the flow separation. Moreover, a dual wake structure evolves through the rotor passage due to highly loaded individual blades. The stage design follows an unconventional approach of tandem rotor-single stator over the reported tandem rotor-tandem stator or only tandem bladed stator configuration. The aerodynamic match between the tandem bladed rotor and stator has been of critical importance in development of this design. The rotor has been designed for highest possible energization of flow by fine tuning the variation of tandem nozzle geometry throughout the span to complement the intended loading profile. The stator is aimed at letting the flow pass through with a chordwise varying diffusion profile. The novelty of the work lies in discussion of tandem rotor and single bladed stator flow physics altogether highlighting the interdependence of decision-making process for both.

Keywords

• tandem rotor
• dca camber
• vortex breakdown
• tip clearance
• flow blockage