<p>Adapting Tandem Bladed rotor configuration brings special flow features at the exit compared to conventional rotor. &nbsp;For tandem bladed rotor, there is presence of strong dual-tip leakage flow, atypical exit flow angle distributions, corner blade separations leading to larger wakes at the exit of rotor to name a few. This makes the aerodynamic design of downstream stator challenging in terms of overall performance as well as operational stability. The modern compressor requisite of being lighter and cost-efficient which needs to be taken care of for both aerodynamic and mechanical requirement. To overcome all these challenges, the cantilever type stator has been chosen and been &nbsp;analysed for present study. The effects of different hub gap sizes of the cantilever stator in combination with tandem bladed axial compressor stage are investigated in this paper. The goal of the work is to get further insights into the aerodynamic performance using detailed flow field. The numerical study was done using reliable ANSYS TurboGrid® for mesh generation and the commercial package ANSYS CFX® 18.0 was used for steady-state simulation. Stationary hub boundary conditions have been employed for the stator with 1% and 2% (of span) clearance. For no clearance case, the region of momentum deficit was observed in the vicinity of the hub endwall and suction surface. The region keeps growing along both streamwise and span wise direction as a low momentum bubble. This low momentum bubble seems to be transported more along the span and towards the suction surface. The solution strategy explored to mitigate the effect of hub corner separation by adapting cantilevered stator. The role played by secondary flow &nbsp;in feeding the low momentum flow along the span is seen to be moderated by the high momentum leakage flow originating from the pressure side. The leakage jet from the blade pressure side reenergized the low momentum fluid on the suction surface refraining it to travel along the span and mitigate its &nbsp;effect by suppressing the separation tendency near end wall region. The formation of large size bubble gets reduced in overall extent both in circumferential and span wise direction. &nbsp;This phenomenon is letting the low momentum flow to pass along the low span region. Numerically obtained results provide &nbsp;an insightful mechanism of the interaction of secondary flow structures and the influence of hub clearance flow. Hub corner stall, which is the consequence of low momentum fluid sweeping across the blade passage near the end wall in the presence of hub clearance. This phenomenon diminishes the &nbsp;extent and overall effect of the hub corner stall which was observed with no-clearance. The interaction of hub leakage vortex and passage vortex leads to mitigation of overall secondary flow adverse effects. As a result, the performance improvement at design and peak pressure mass flow conditions have been elucidated by using cantilever stator.</p>

Numerical Investigations on Application of Cantilever Stator on Aerodynamic Performance of Tandem Bladed Axial-Flow Compressor Stage

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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