On the Periodically Unsteady Interaction of Wakes, Secondary Flow Development and Boundary Layer Flow in an Annular LPT Cascade: Part 2 — Numerical Investigation

Winhart, Benjamin; Sinkwitz, Martin; Engelmann, David; Mare, Francesca di; Mailach, Ronald

doi:10.1115/gt2018-76873

Cited by 5 publications

(3 citation statements)

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“…Thus, especially in the hub region, a distinction between passage vortex (PV) and the pressure side leg of the horse shoe vortex (HSV-PL) is enabled for t/T BP = 1/3, as the HSV-PL slides beneath the PV and pushes it along the suction side trailing edge radially inward, before it blends again with the PV. As could be shown in detail in [52,53,55,56], this periodic and short-duration event is based on the upstream wake impact on the developing HSV-PL, which is massively diverted in the front part of the blade passage by the impinging wake structure. Also, the unsteadiness of the suction side corner separation, shaping the concentrated shed vortex (CSV) can be realized.…”

Section: Impact On the Secondary Flow Structuresmentioning

confidence: 98%

“…The presented investigations give a brief outline of key findings from recent publications by the authors, where the unsteady impact of periodic bar wakes on the flow field downstream of the stator row as well as on the stator profile pressures and boundary layers were discussed. For details, please see [51][52][53][54][55][56][57][58].…”

Section: Sub-project D-influence Of Periodic Wakes On the Transient Near-wall Flow In Anmentioning

confidence: 99%

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Near-Wall Flow in Turbomachinery Cascades—Results of a German Collaborative Project

Engelmann

Sinkwitz

Mare

et al. 2021

IJTPP

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This article provides a summarizing account of the results obtained in the current collaborative work of four research institutes concerning near-wall flow in turbomachinery. Specific questions regarding the influences of boundary layer development on blades and endwalls as well as loss mechanisms due to secondary flow are investigated. These address skewness, periodical distortion, wake interaction and heat transfer, among others. Several test rigs with modifiable configurations are used for the experimental investigations including an axial low speed compressor, an axial high-speed wind tunnel, and an axial low-speed turbine. Approved stationary and time resolving measurements techniques are applied in combination with custom hot-film sensor-arrays. The experiments are complemented by URANS simulations, and one group focusses on turbulence-resolving simulations to elucidate the specific impact of rotation. Juxtaposing and interlacing their results the four groups provide a broad picture of the underlying phenomena, ranging from compressors to turbines, from isothermal to non-adiabatic, and from incompressible to compressible flows.

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Section: Impact On the Secondary Flow Structuresmentioning

confidence: 98%

Section: Sub-project D-influence Of Periodic Wakes On the Transient Near-wall Flow In Anmentioning

confidence: 99%

Near-Wall Flow in Turbomachinery Cascades—Results of a German Collaborative Project

Engelmann

Sinkwitz

Mare

et al. 2021

IJTPP

Self Cite

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“…They found that the wake reduced the end-wall secondary flow losses at higher Reynolds number [21]. Winhart et al analyzed the complex interactions between the wake, the secondary flow structure and the boundary layer flow to determine the contribution of the secondary flow components to the turbulent kinetic energy [22,23]. Darji studied the generation location of horseshoe vortices and the development pattern of endwall flow under different working conditions [24].…”

Section: Introductionmentioning

confidence: 99%

Effects of Flow Coefficient on Turbine Aerodynamic Performance and Loss Characteristics

Yang

Luo

et al. 2022

International Journal of Aerospace Engineering

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The effects of flow coefficient on the gas flow and loss characteristics inside the high-pressure turbine is investigated using a numerical simulation. In this paper, the midspan of the first stator of the “Lisa” 1.5 stage high-pressure turbine is used as a prototype to obtain different flow coefficients by changing the stagger angle and the exit angle. The boundary conditions of all cases are consistent with the experimental data of “Lisa”. The results show that the flow coefficient is decreased from 0.478 to 0.374 as the stagger angle is varied from 44.2° to 56.2° and from 0.630 to 0.341 as the exit angle is varied from 63° to 75°. Large stagger angle or large exit angle both cause an increase in turbine aerodynamic losses. The similarity between the two is that both cause enhanced effect of transverse secondary flow in the passage. The difference is that with large stagger angle, the adverse pressure gradient affects a large area, resulting in large boundary layer losses; with large exit angle, the passage vortex is weakened but with a large influence area.

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On the Periodically Unsteady Interaction of Wakes, Secondary Flow Development, and Boundary Layer Flow in An Annular Low-Pressure Turbine Cascade: An Experimental Investigation

Sinkwitz

Winhart

Engelmann

et al. 2019

Journal of Turbomachinery

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The experimental results reported in this contribution address the time-dependent impact of periodically unsteady wakes on the development of profile and end wall boundary layers and consequently on the secondary flow system. Experimental investigations are conducted on an annular 1.5 stage axial turbine rig at Ruhr-Universität Bochum’s Chair of Thermal Turbomachines and Aeroengines. The object under investigation is a modified T106 profile low-pressure turbine (LPT) stator row at a representative exit flow Reynolds number of 200,000. By making use of an annular geometry instead of a linear cascade, the influence of curvilinear end walls, nonuniform, increasing pitch across the span and radial flow migration can be represented. Incoming wakes are generated by a variable-speed driven rotor equipped with cylindrical bars. Special emphasis is put on the wake-induced recurrent formation, suppression, weakening, and displacement of individual vortices and separated flow regimes. For this, based on a comprehensive set of time-resolved measurement data, the interaction of impinging bar wakes and boundary layer flow and thus separation and its periodic manipulation along the passage end walls and on the blade suction surface are studied within the frequency domain.

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On the Periodically Unsteady Interaction of Wakes, Secondary Flow Development and Boundary Layer Flow in an Annular LPT Cascade: Part 2 — Numerical Investigation

Cited by 5 publications

References 0 publications

Near-Wall Flow in Turbomachinery Cascades—Results of a German Collaborative Project

Near-Wall Flow in Turbomachinery Cascades—Results of a German Collaborative Project

Effects of Flow Coefficient on Turbine Aerodynamic Performance and Loss Characteristics

On the Periodically Unsteady Interaction of Wakes, Secondary Flow Development, and Boundary Layer Flow in An Annular Low-Pressure Turbine Cascade: An Experimental Investigation

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