The Effect of Manufacturing Variations on Unsteady Interaction in a Transonic Turbine

Clark, John P.; Beck, Jeff; Kaszynski, Alex A.; Still, Angela; Ni, Ron-Ho

doi:10.1115/1.4039361

Cited by 4 publications

(1 citation statement)

References 34 publications

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“…In addition, the computational cost of URANS models often make them impractical for the purposes of design, let alone for high-volume assessments. If resources permit, URANS CFD could provide useful insights for dynamic blade loading (Clark et al, 2018).…”

Section: Digital Twinmentioning

confidence: 99%

The Required Aerodynamic Simulation Fidelity to Usefully Support a Gas Turbine Digital Twin for Manufacturing

Lee¹,

Dawes²,

Coull³

2020

Proceedings of Global Power &Amp; Propulsion Society

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With the imminent digitalisation of the manufacturing processes of gas turbine components, a large volume of geometric data of as-manufactured parts is being generated. This geometric data can be used in aerodynamic simulations to predict component performance. Both the cost and accuracy of these simulations increase with their fidelity. To efficiently exploit Digital Twin technology, one must therefore understand how realistic the aerodynamic simulations need to be to give useful performance predictions. This paper considers this issue for a sample of scrapped high-pressure turbine rotor blades from a civil aero engine. The measured geometric data was used to build aerodynamic models of varying degrees of realism, ranging from quasithree-dimensional blade sections for an Euler solver to three-dimensional, multi-passage and multi-stage Reynolds-Averaged-Navier-Stokes models. The flow near the tip of these shrouded blades is sensitive to manufacturing variability and can switch between two quasi-stable horseshoe vortex modes. In general, capacity and exit flow angle can be adequately predicted by three-dimensional, single-passage calculations: averaging single-passage calculations gives a good prediction of the multi-passage behaviour. For efficiency and stage loading, the approach of averaging single-passage calculations is less accurate as the multi-passage behaviour requires an accurate prediction of the horseshoe vortex modes. Aerodynamic Simulation Hierarchy The aerodynamic environment of a turbine blade is complex and can only be captured using physics-based simulations. Computational Fluid Dynamics (CFD) tools that encompass a range of fidelities have been used by various published studies and they will be discussed here in the order of increasing fidelity. Considering the high volume of manufactured blades, rapid CFD tools like the Multiple blade Interacting Streamtube Euler Solver (MISES) (Drela, 1985) are attractive. MISES is a streamtube Euler solver coupled to an integral boundary layer code that is limited to quasi-three-dimensional (Q3D) blade sections. It has been used to assess compressor (Garzon

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Section: Digital Twinmentioning

confidence: 99%

The Required Aerodynamic Simulation Fidelity to Usefully Support a Gas Turbine Digital Twin for Manufacturing

Lee¹,

Dawes²,

Coull³

2020

Proceedings of Global Power &Amp; Propulsion Society

View full text Add to dashboard Cite

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Effects of Downstream Vane Bowing and Asymmetry on Unsteadiness in a Transonic Turbine

Clark

Anthony

Ooten

et al. 2018

Journal of Turbomachinery

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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 (3D), 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 nonuniform pitch.

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Surrogate Modeling of Manufacturing Variation Effects on Unsteady Interactions in a Transonic Turbine

Brown

Beck²,

Kaszynski³

et al. 2018

Journal of Engineering for Gas Turbines and Power

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This effort develops a surrogate modeling approach for predicting the effects of manufacturing variations on performance and unsteady loading of a transonic turbine. Computational fluid dynamics (CFD) results from a set of 105 as-manufactured turbine blade geometries are used to train and validate the surrogate models. Blade geometry variation is characterized with point clouds gathered from a structured light, optical measurement system and as-measured CFD grids are generated through mesh morphing of the nominal design grid data. Principal component analysis (PCA) of the measured airfoil geometry variations is used to create a reduced basis of independent surrogate model parameters. It is shown that the surrogate model typically captures between 60% and 80% of the CFD predicted variance. Three new approaches are introduced to improve surrogate effectiveness. First, a zonal PCA approach is defined which investigates surrogate accuracy when limiting analysis to key regions of the airfoil. Second, a training point reduction strategy is proposed that is based on the k–d tree nearest neighbor search algorithm and reduces the required training points up to 38% while only having a small impact on accuracy. Finally, an alternate reduction approach uses k-means clustering to effectively select training points and reduces the required training points up to 66% with a small impact on accuracy.

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The Effect of Manufacturing Variations on Unsteady Interaction in a Transonic Turbine

Cited by 4 publications

References 34 publications

The Required Aerodynamic Simulation Fidelity to Usefully Support a Gas Turbine Digital Twin for Manufacturing

The Required Aerodynamic Simulation Fidelity to Usefully Support a Gas Turbine Digital Twin for Manufacturing

Effects of Downstream Vane Bowing and Asymmetry on Unsteadiness in a Transonic Turbine

Surrogate Modeling of Manufacturing Variation Effects on Unsteady Interactions in a Transonic Turbine

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