Towards Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

Jain, Nishan; Bravo, Luis; Kim, Dokyun; Murugan, Muthuvel; Ghoshal, Anindya; Ham, Frank; Flatau, Alison B.

doi:10.1115/gt2019-91592

Cited by 3 publications

(4 citation statements)

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“…With the baseline geometry providing tip clearance of 16% rotor chord, the simulations predicted adiabatic efficiencies of 51.7%, 51.6% and 54.9% when Grids A-C were used, respectively. Additional details of predicted flow-field in grid sensitivity simulations at 16% tip clearance is available in the authors' previous work [46]. The predicted adiabatic efficiency values are lower than typically observed in gas turbine engines and are likely caused by the losses incurred due to the large tip clearance in the baseline CAD geometry.…”

Section: Effect Of Grid Resolutionmentioning

confidence: 97%

“…The variation in adiabatic efficiency with rotor RPM for the two tip clearances is shown as a bar chart in Figure 24. The adiabatic efficiencies at 16% chord tip clearance were obtained from the authors' previous publication [46]. As evident in the bar chart, the reduction in efficiency with deviation in RPM from design value highlights the performance deterioration at off-design conditions due to the increase in unsteady flow interaction.…”

Section: Effect Of Rotor Speedmentioning

confidence: 99%

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Massively Parallel Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

et al. 2020

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Gas turbine engines are required to operate at both design and off-design conditions that can lead to strongly unsteady flow-fields and aerodynamic losses severely impacting performance. Addressing this problem requires effective use of computational fluid dynamics tools and emerging models that resolve the large scale fields in detail while accurately modeling the under-resolved scale dynamics. The objective of the current study is to conduct massively parallel large eddy simulations (LES) of rotating turbomachinery that handle the near-wall dynamics using accurate wall models at relevant operating conditions. The finite volume compressible CharLES solver was employed to conduct the simulations over moving grids generated through Voronoi-based unstructured cells. A grid sensitivity analysis was carried out first to establish reliable parameters and assess the quality of the results. LES simulations were then conducted to understand the impact of blade tip clearance and operating conditions on the stage performance. Variations in tip clearance of 3% and 16% chord were considered in the analysis. Other design points included operation at 100% rotor speed and off-design conditions at 75% and 50% of the rotor speed. The simulation results showed that the adiabatic efficiency improves dramatically with reduction in tip gap due to the decrease in tip leakage flow and the resulting flow structures. The analysis also showed that the internal flow becomes highly unsteady, undergoing massive separation, as the rotor speed deviates from the design point. This study demonstrates the capability of the framework to simulate highly turbulent unsteady flows in a rotating turbomachinery environment. The results provide much needed insight and massive data to investigate novel design concepts for the US Army Future Vertical Lift program.

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Section: Effect Of Grid Resolutionmentioning

confidence: 97%

Section: Effect Of Rotor Speedmentioning

confidence: 99%

Massively Parallel Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

et al. 2020

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“…In order to cope with the above-mentioned problems, the wide working condition power turbine blades are developing in the direction of highlyloaded, large incidence angle, and low Reynolds number state. The United States has carried out more indepth research work in this research area, including high-precision calculation methods, 48,55 the influences of incidence angle, 56 inlet turbulence, [57][58][59][60][61] and Reynolds number effects, [62][63][64] etc. The specific research results can be found in related papers.…”

Section: Flow and Loss Characteristics Of Variable Speed Power Turbinesmentioning

confidence: 99%

“…Figure 4.Representative design and off-design conditions under variable speed power turbine operation 55. …”

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Advances in aerodynamics of power turbines for marine and aviation applications

Gao

Zhao

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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The use of power turbines has the advantage of flexible output load adjustment, and is a major configuration of marine gas turbines and aviation turboshaft/turboprop engines. Marine gas turbines and aviation turboshafts and turboprop engines generally have multiple working states and multiple working conditions change laws, which cause the aerodynamic performance of power turbines to fluctuate greatly with changes in working conditions, and different variable working conditions have a severe impact on the turbine loss characteristics. Therefore, it is necessary to deeply understand the internal flow mechanism of power turbines under off-design working conditions in different power turbine application modes, and carry out researches on the design methods of power turbines under wide working conditions. This paper summarizes and analyzes the recent advances in the field of aerodynamics of power turbines for marine and aviation applications. This review covers the following topics that are important for power turbine designs: (1) turbine flow loss prediction models under multiple operating conditions, (2) aerodynamic design and flow mechanism of power turbines for marine gas turbines, (3) aerodynamics of variable speed power turbines for turboshaft/turboprop engines, and (4) other issues about power turbines for marine and turboshaft/turboprop engines. The emphasis is placed on the aerodynamic design and flow mechanism of marine and aviation power turbines. We also present our own insights regarding the current research trends and the prospects for future developments.

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