| Cantilevered stators and shrouded stators are two main types of stators in axial compressor.The research on loss characteristic of two stators provides theoretical basis for flow optimal design near hub.This paper selects the rear stage of HPC as subject of study,establishes idealized stator,shrouded stator and cantilevered stator computational models,and performs the numerical simulation.Meanwhile the shrouded stator and cantilevered stator models with different clearance sizes are calculated to investigate the effect of gap size on aerodynamic performance and flow field in detail.Finally,further computations and analysis about shrouded stator with 1% span seal clearance and cantilevered stator with 2.5% span hub gap are carried out by both steady and unsteady CFD methods.The results show that when the idealist stator is used to instead of the shrouded one in CFD simulation,the total pressure loss of the stator is underestimated,the total pressure ratio of the following rotor is estimated.While the stator is shrouded,the leakage flow from labyrinth seal cavity influences the total pressure loss distribution below nearly 30% span.While the stator is cantilevered,the total pressure loss becomes more sensitive to the hub gap for large hub clearance(beyond 3.5% span);the leakage flow from hub clearance influences the total pressure loss and outlet flow angle distributions below nearly 60% span.At the design point,comparing with SS1%,the total pressure loss coefficient of CS2.5% decreases 8.46%.Cantilevered stator performance better because the rotating hub drives the low momentum flow and remove the corner stall,but the flow of following rotor is worse and non-matching as a result of the changed outlet flow angle from S1.Comparing with steady simulation method,the computation results with unsteady method have higher wake loss of the stator.In the channel the the vortex structure dominated by leakage flow changes most intense at different times. |
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