An Unstructured Shock-Fitting Technique For Three-Dimensional Flows With Shock Interactions

Accurate predictions of unsteady forcing on turbine blades are essential for the avoidance of high-cycle-fatigue issues during turbine engine development. Further, if one can demonstrate that predictions of unsteady interaction in a turbine are accurate, then it becomes possible to anticipate resonant-stress problems and mitigate them through aerodynamic design changes during the development cycle. A successful reduction in unsteady forcing for a transonic turbine with significant shock interactions due to downstream components is presented here. A pair of methods to reduce the unsteadiness was considered and rigorously analyzed using a three-dimensional, time resolved Reynolds-Averaged Navier Stokes (RANS) solver. The first method relied on the physics of shock reflections itself and involved altering the stacking of downstream components to achieve a bowed airfoil. The second method considered was circumferentially-asymmetric vane spacing which is well known to spread the unsteadiness due to vane-blade interaction over a range of frequencies. Both methods of forcing reduction were analyzed separately and predicted to reduce unsteady pressures on the blade as intended. Then, both design changes were implemented together in a transonic turbine experiment and successfully shown to manipulate the blade unsteadiness in keeping with the design-level predictions. This demonstration was accomplished through comparisons of measured time-resolved pressures on the turbine blade to others obtained in a baseline experiment that included neither asymmetric spacing nor bowing of the downstream vane. The measured data were further compared to rigorous post-test simulations of the complete turbine annulus including a bowed downstream vane of non-uniform pitch.

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Numerical Investigation of Wake-Shock Interactions and Clocking in a Transonic HP Turbine

Volume 6: Turbo Expo 2003, Parts A and B ◽

10.1115/gt2003-38401 ◽

2003 ◽

Cited By ~ 4

Author(s):

Michele Marconcini ◽

Roberto Pacciani

Keyword(s):

Shock Waves ◽

Gas Turbine ◽

Three Dimensional ◽

Frame Of Reference ◽

Heavy Duty ◽

Blade Loading ◽

Shock Interactions ◽

Blade Row ◽

Wake Passing ◽

Stators And Rotors

A quasi-three-dimensional, blade-to-blade, time-accurate, viscous solver was used for the clocking optimization of a modern transonic heavy-duty, two stage gas turbine. Both stators and rotors operate in a transonic regime with fish-tail shock systems at the blade row exit. These shock systems interact with both stator and rotor wakes. A sensible reduction in the strength of shock waves was observed due to the upstream blade row wake passing. Such wake-shock interactions occur in the inter-blade gap, around locations which are fixed in the frame of reference of the downstream blade-row. The exploitation of such an effect to optimize the axial/circumferential position of blade rows is still compatible with the axial gap values commonly used for these kinds of stages. The results of the clocking investigation will be presented and discussed in terms of unsteady blade loading and efficiency variations.

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Three-dimensional shock interactions and vortices on a V-shaped blunt leading edge

Physics of Fluids ◽

10.1063/1.5101031 ◽

2019 ◽

Vol 31 (8) ◽

pp. 086102 ◽

Cited By ~ 3

Author(s):

Enlai Zhang ◽

Zhufei Li ◽

Yiming Li ◽

Jiming Yang

Keyword(s):

Three Dimensional ◽

Leading Edge ◽

Shock Interactions ◽

Blunt Leading Edge

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NUMERICAL SIMULATION OF THREE-DIMENSIONAL SHOCK-SHOCK INTERACTIONS ON A BLUNT BODY

International Journal of Computational Fluid Dynamics ◽

10.1080/10618569308904471 ◽

1993 ◽

Vol 1 (3) ◽

pp. 177-196 ◽

Cited By ~ 2

Author(s):

D. J. SINGH ◽

A. KUMAR ◽

S. N. TIWARI

Keyword(s):

Numerical Simulation ◽

Blunt Body ◽

Three Dimensional ◽

Shock Interactions

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Glancing interactions between single and intersecting oblique shock waves and a turbulent boundary layer

Journal of Fluid Mechanics ◽

10.1017/s0022112086000952 ◽

1986 ◽

Vol 170 ◽

pp. 411-433 ◽

Cited By ~ 21

Author(s):

D. J. Mee ◽

R. J. Stalker ◽

J. L. Stollery

Keyword(s):

Boundary Layer ◽

Turbulent Boundary Layer ◽

Pressure Field ◽

Superposition Principle ◽

Three Dimensional ◽

Oblique Shock ◽

Shock Interactions ◽

Expansion Waves ◽

Shock Generator ◽

Boundary Layer Interaction

The three-dimensional interactions of weak swept oblique shock and expansion waves and a turbulent boundary layer on a flat plate are investigated. Upstream influences in a single swept interaction are found to be consistent with a model of the flow involving shock/boundary-layer interaction characteristics. The model implies that there is more rapid thickening of the boundary layer close to the shock generator and this is seen to be consistent with surface streamline patterns. It is also found that a superposition principle, which is inherent in the triple-deck model of shock/boundary-layer interactions proposed by Lighthill, can be used to predict the pressure field and surface streamlines for the case of intersecting shock interactions and for the intersection of a shock with a weak expansion.

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