Detached Eddy Simulation: Recent Development and Application to Compressor Tip Leakage Flow

He, Xiao; Zhao, Fuquan; Vahdati, Mehdi

doi:10.1115/1.4052019

Cited by 27 publications

(16 citation statements)

References 54 publications

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“…Previous RANS simulations have inferred that the SA model underpredicts the eddy viscosity in the tip blockage cell and hence leads to premature stall. 28,46 This work confirms that modifying the production term of the SA model in the tip blockage cell is conceptually correct.…”

Section: Further Discussion a Rans Turbulence Modeling Of Tip Leakage...supporting

confidence: 74%

“…The second-order implicit time integration scheme is applied for temporal discretization. For simulation of turbulent flows, the standard Spalart-Allmaras turbulence model 25 and its variants 26 are available for the RANS branch, and the standard DDES method 27 and its upgrades 28 are available for the hybrid RANS/LES branch. Validation and verification of HADES can be found in previous works.…”

Section: Methodology a Flow Solvermentioning

confidence: 99%

“…Validation and verification of HADES can be found in previous works. 26,28 In this work, a variation of the SA-based DDES method 28 is used. Compared to the original formulation, 27 an alternative grid spacing is adopted as described in Eq.…”

Section: Methodology a Flow Solvermentioning

confidence: 99%

“…At the inlet, the measured radial profile of total pressure, total temperature, and velocity directions are prescribed. Since the measured freestream TKE is two orders of magnitude smaller than those generated by the Kelvin-Helmholtz instability in the main TLV core, 28 no additional turbulent perturbations are given at the inlet boundary. A choked nozzle 37 is attached to the rotor exit, whose throat area is adjusted to change the compressor operating condition.…”

Section: Case Descriptionmentioning

confidence: 98%

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Spectral proper orthogonal decomposition of compressor tip leakage flow

Zhou

Rigas

et al. 2021

Physics of Fluids

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To identify the spatiotemporal coherent structure of compressor tip leakage flow, spectral proper orthogonal decomposition (SPOD) is performed on the near-tip flow field and the blade surface pressure of a low-speed compressor rotor. The data used for the SPOD analysis are obtained by delayed-detached eddy simulation, which is validated against the experimental data. The investigated rotor near-tip flow field is governed by two tip leakage vortices (TLV), and the near-tip compressor passage can be divided into four zones: the formation of main TLV (Zone I), the main TLV breakdown (Zone II), the formation of tip blockage cell (Zone III), and the formation of secondary TLV (Zone IV). Modal analysis from SPOD shows that a major part of total disturbance energy comes from the main TLV oscillating mode in Zone I and the main TLV vortex shedding mode in Zone III, both of which are low-frequency and low-rank; on the contrary, modal components in Zones II and IV are broadband and non-low-rank. Unsteady blade forces are mainly generated by the impingement of the main TLV on the blade pressure surface in Zone III, rather than the detachment of the secondary TLV from the blade suction surface in Zone IV. These identified coherent structures provide valuable knowledge for the aerodynamic/aeroelastic effects, turbulence modeling, and reduced-order modeling of compressor tip leakage flow.

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Section: Further Discussion a Rans Turbulence Modeling Of Tip Leakage...supporting

confidence: 74%

Section: Methodology a Flow Solvermentioning

confidence: 99%

Section: Methodology a Flow Solvermentioning

confidence: 99%

Section: Case Descriptionmentioning

confidence: 98%

See 2 more Smart Citations

Spectral proper orthogonal decomposition of compressor tip leakage flow

Zhou

Rigas

et al. 2021

Physics of Fluids

Self Cite

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“…Structured/Unstructured hybrid grids are compatible with the solver. The validations of the solver for a range of flows can be found in the previous works ( [27], [28], and [29]). The time integration scheme is implicit and second order accurate.…”

Section: Methodsmentioning

confidence: 99%

Investigations of the Unsteady Aerodynamic Characteristics for Intakes at Crosswind

Piovesan

Zhang

Vahdati

et al. 2022

Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions

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The ground vortex generated in front of an intake operating near the ground and subjected to crosswind is investigated using CFD and compared to the experiments. The flow field of a scale-model intake is numerically simulated with both steady and unsteady approach, with the aim of predicting ground vortex effects and to characterize the vortex unsteady behaviour. The experimental results showed that for an intake near the ground under crosswind the ground vortex that forms under the intake and the in-duct separation, when present, exhibit unsteady behaviour that becomes stronger as the crosswind velocity is increased. The simulations indicate that a steady-state approach only partially reproduces the time-averaged ground vortex characteristics and in-duct distortion losses, while an unsteady approach shows a lower level of unsteadiness compared to the experimental observations. The consequences of the unsteady flow in the intake on the fan aerodynamic and aeroelastic stability are finally discussed to reinforce that these can result in significant non-synchronous vibration (NSV) and loss of stall margin which cannot be adequately assessed if no unsteady component of the inlet distortions is taken into account.

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