Aerodynamic limits of gas turbine compressor during high air offtakes for minimum load extension

Szymański, Artur; Igie, Uyioghosa; Abudu, Kamal; Hamilton, Richard

doi:10.1016/j.applthermaleng.2021.116697

Cited by 5 publications

(4 citation statements)

References 33 publications

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“…The simulation cases of power augmentation and ramp-up rates are also described in the work from an engine-level thermodynamic analysis perspective. Similarly, some of the engine performance details are presented in Szymanski et al [12] that is related to the present study, though with a different context (air extraction).…”

Section: D Analytical Engine Model and Performancementioning

confidence: 74%

“…The rotor's tip gap was assumed to be 1% of the blade height, with cantilevered stators and no hub or interstage leakages. The CFD setup and verification, including mesh and turbulence model sensitivity for the design case, are presented in Szymanski et al 12 that is related to this study. The referred work shows that the model meets compressor aerodynamic requirements based on parameters such as the diffusion factor, total pressure loss coefficient, axial velocity ratio and flow coefficient.…”

Section: D Cfd Multi-stage Compressor Model and Assessment Metricsmentioning

confidence: 99%

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Aerodynamic limits air injection for heavy-duty gas turbine: Compressor aerodynamic limits for power augmentation and ramp-up capabilities

Szymański

Igie

Hamilton

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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Improved operational flexibility of gas turbines can play a major role in stabilising the electric power grid, by backing up intermittent renewable power. Gas turbines offer on-demand power and fast dispatch of power that is vital when renewable power reduces. This has brought about increasing demand to improve the ramp-up rate of gas turbines. One approach is through the injection of compressed air from energy storage or an auxiliary compressor. This method is the focus of the present work, which shows for the first time, the implications and limits of compressor air injection in a high-fidelity Computational Fluid Dynamics model (CFD). The 3D multi-stage model of the compressor was developed in ANSYS CFX v19.2, while the boundary conditions related to the injection cases have been obtained from a corresponding 0D engine model. The upper limits to air injection determine how much air can be injected into the engine, providing indicative values of power augmentation and ramp-up rate capabilities. These have been previously addressed by the authors using 0D models that do not consider the compressor aerodynamics in great detail. The CFD study has shown that for power augmentation, 16% of compressed air (based on compressor exit) is allowed based on the onset of stall. It also shows that increasing air injection amplifies losses, blockage factor and absolute velocity angle. Also, about 30% of the blade span from the hub is dominated by a rise in the total pressure loss coefficient, except the outlet guide vane for which separation occurs at the tip. For the ramp-up rate analysis, up to 10% air injection is shown to be sustainable. The work shows that the improvements in the 0D analytical engine model are plausible, in addition to demonstrating similar limits at different ambient temperatures.

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Section: D Analytical Engine Model and Performancementioning

confidence: 74%

Section: D Cfd Multi-stage Compressor Model and Assessment Metricsmentioning

confidence: 99%

Aerodynamic limits air injection for heavy-duty gas turbine: Compressor aerodynamic limits for power augmentation and ramp-up capabilities

Szymański

Igie

Hamilton

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

Self Cite

View full text Add to dashboard Cite

show abstract

“…Historically, the choice of aspect ratio (AR) has always involved the simultaneous consideration of a number of key design parameters such as work output per stage, diffusion, efficiency, surge margin and mechanical integrity. This discussion is related to changing the compressor load by means of geometric changes, although recent research also indicates the possibility to change the machine load based on air extraction [5].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Blade Aspect Ratio’s Influence on High-Speed Axial Compressor Performance

Silva,

Grönstedt,

Xisto

et al. 2024

Aerospace

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The ratio between blade height and chord, named the aspect ratio (AR), plays an important role in compressor aerodynamic design. Once selected, it influences stage performance, blade losses and the stage stability margin. The choice of the design AR involves both aerodynamic and mechanical considerations, and an aim is frequently to achieve the desired operating range while maximizing efficiency. For a fixed set of aerodynamic and geometric parameters, there will be an optimal choice of AR that achieves a maximum efficiency. However, for a state-of-the-art aero-engine design, optimality means multi-objective optimality, that is, reaching the highest possible efficiency for a number of operating points while achieving a sufficient stability margin. To this end, the influence of the AR on the performance of the first rotor row of a multistage, multi-objective, high-speed compressor design is analyzed. A careful setup of the high-speed aerodynamic design problem allows the effect of the AR to be isolated. Close to the optimal AR, only a modest efficiency variation is observed, but a considerable change in compressor stability margin (SM) is noted. Decreasing the AR allows for increasing efficiency, but at the expense of a reduced surge margin. This allows the designer to trade efficiency for stability. Increasing the AR, however, is shown to reduce both the surge margin and efficiency; hence, a distinct optimality in stability is observed for the analyzed rotor blade row. In this work, optimality in the surge margin with respect to the AR is observed, whereas there is a close to optimal efficiency. The predicted range from AR = 1.10 to AR = 1.64 is only indicative, considering that the definition of multi-objective optimality requires balancing efficiency and the surge margin and that the choice of balancing these two criteria requires making a design choice along a pareto optimal front.

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“…Historically, the choice of aspect ratio (AR) has always involved the simultaneous consideration of a number of key design parameters such as work output per stage, diffusion, efficiency, surge margin and mechanical integrity. This discussion is related to changing compressor load by means of geometric changes, although recent research also indicates the possibility to change the machine load based on air extraction [5].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Blade Aspect Ratio Influence on High-Speed Axial Compressor Performance

Silva,

Grönstedt,

Xisto

et al. 2024

Preprint

View full text Add to dashboard Cite

The ratio between blade height and chord, named aspect ratio (AR), plays an important role in compressor aerodynamic design. Once selected, it influences stage performance, blade losses, and the stage stability margin. The choice of the design AR involves both aerodynamic and mechanical considerations, and a reasonable aim is frequently to achieve a desired operating range while maximizing efficiency. For a fixed set of aerodynamic and geometric parameters there will be an optimal choice in AR that achieves a maximum efficiency. However, for a state-of-the-art aero-engine design optimality means multi-objective optimality, that is reaching the highest possible efficiency for a number of operating points while achieving a sufficient stability margin. To this end, the influence of the AR on the performance of the first rotor row of a multistage multi-objective high-speed compressor design is analyzed. A careful setup of the high-speed aerodynamic design problem allows the effect of the AR to be isolated. Close to the optimal AR, only a modest efficiency variation is observed, but a considerable change in compressor stability margin (SM) is noted. Decreasing the AR allows for an increasing efficiency, but at the expense of a reduced surge margin. This allows the designer to trade efficiency for stability. Increasing the AR, however, is shown to reduce both surge margin and efficiency, hence a distinct optimality in stability is observed for the analyzed rotor blade row. In this work, the optimality in surge margin with respect to AR is observed whereas a close to optimal efficiency. The predicted range from AR=1.10 to AR=1.64, is only indicative, considering that the definition of a multi-objective optimality requires balancing efficiency and surge margin and that the choice of balancing these two criteria requires making a design choice along a pareto optimal front.

show abstract

Aerodynamic limits of gas turbine compressor during high air offtakes for minimum load extension

Cited by 5 publications

References 33 publications

Aerodynamic limits air injection for heavy-duty gas turbine: Compressor aerodynamic limits for power augmentation and ramp-up capabilities

Aerodynamic limits air injection for heavy-duty gas turbine: Compressor aerodynamic limits for power augmentation and ramp-up capabilities

Analysis of Blade Aspect Ratio’s Influence on High-Speed Axial Compressor Performance

Analysis of Blade Aspect Ratio Influence on High-Speed Axial Compressor Performance

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