Measurement and Prediction of Tip Leakage Losses in an Axial-Flow Transonic Turbine

Wehner, M. U.; Bütikofer, J.; Hustad, C-W.; Bölcs, A.

doi:10.1115/97-gt-203

Cited by 4 publications

(2 citation statements)

References 16 publications

(13 reference statements)

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“…The principal sources of these losses in the axial turbine are profile, shock, tip-leakage, and end-wall losses, which have already been reported by Wei 51 and discussed by many authors. [52][53][54][55][56][57][58][59][60][61] Concerning the velocity variation in the HPT, the velocity gradient in the stator was positive because the static enthalpy of temperature was then converted to kinetic energy. So, in the stator, the fluid was accelerated, while the temperature decreased in the rotation direction.…”

Section: Baseline 1d; 2d Full Hpt Flow-path Calculationmentioning

confidence: 99%

Aero-thermodynamic and chemical process interactions in an axial high-pressure turbine of aircraft engines

Nguyen

Nguyen-Tri

Vancassel

et al. 2018

International Journal of Engine Research

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Precise investigation of aero-thermodynamic and chemical processes relating to environmental precursor pollutants in an aircraft turbine is challenging because of the complexity of transformation processes at high temperature and high pressure. We present here, for the first time, new insights into the study of aero-thermodynamic processes, formation of nitrate and sulfate aerosol precursors, and investigate the influence of chemical processes on aero-thermodynamics. We also shed light on the effect of three-dimensional blade profile, radial spacing, and rotor speed on the performance of a high-pressure turbine. We highlight that flow vortex and the variation of chemical formation which appear in both rear stator blades and rear rotor blades. We found that the chemical processes were affected by the evolution of temperature (maximum of 16.9%) and flow velocity (maximum of 38.8%). Contrary to the conservative one-dimensional and two-dimensional modeling, which provide only the flow trends and flow evolution at cylindrical surface, respectively, our three-dimensional modeling approach offers the possibility of combining information on radial spacing and rotor-speed effect by providing three-dimensional images of spatial-geometry effect on aero-thermodynamic and chemical processes. Quantitatively, the magnitude of change in aero-thermodynamics and nitrogen oxidation may be expected to be up to 17% and 48%, respectively, over a stage of the high-pressure turbine.

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Section: Baseline 1d; 2d Full Hpt Flow-path Calculationmentioning

confidence: 99%

Aero-thermodynamic and chemical process interactions in an axial high-pressure turbine of aircraft engines

Nguyen

Nguyen-Tri

Vancassel

et al. 2018

International Journal of Engine Research

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“…No.1 with gap height 3mm, the predicted leakage loss gm) increased from 0.041 to 0.052, when including the additional entropy generation due to a shock within the gap. Wehner et al(1997) originally underpredicted losses for test Case No.2 in the annular cascade, and therefore included an empirical factor increasing the tangent of the flow angle by 1.13. To achieve a similar correction using the modified loss value obtained for Case No.1, resulted in a factor of 1.18.…”

Section: On Casementioning

confidence: 99%

Investigation of Tip Leakage Effects in Transonic Flow Using a Parallel Unstructured Navier-Stokes Code

Hustad

Bölcs

Wehner³

1997

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery

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Calculated results for tip flow around two different blade configurations are presented and compared with experimental data. The first configuration (case number 1) is a flat-plate profile tested in a linear transonic tunnel — the profile is an idealized representation of the aft-section of some highly curved turbine blades. The second configuration (case number 2) originates from the outer profile on the last-stage-blade of a steam turbine, however it is also reminiscient of a section from a turbine blade with supersonic exit flow. This configuration was tested in an annular cascade at Mach numbers representative of engine operating conditions. The computed results were obtained using a parallel 3D unstructured Navier-Stokes code. The code runs on a work-station cluster, as well as being optimized for the 256 processor Cray T3D at EPFL: the code is capable of gigaflop performance using more than 3 million cells — adaptive mesh refinement thus allows enhanced resolution within the tip gap region. For each configuration we have calculated two Runs. In both cases, Run-1 is similar to the experimental conditions, so that direct comparison between measured and calculated results is possible. With case number 1/Run-2 we re-calculated the flow without imposing a prescribed inflow boundary-layer along the sidewall. Comparison between the two runs helped reveal how free-stream total pressure can establish itself within the tip gap region. For the second configuration — in the annular cascade — we were interested in observing the influence of relative movement between the blade tip and adjacent sidewall. Hence for case number 2/Run-2 we imposed a circumferential velocity on the adjacent sidewall. This modified the effective sidewall boundary-layer and had a noticeable influence on the development of the tip-leakage flow.

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Influences of a multi-cavity tip on the blade tip and the over tip casing aerothermal performance in a high pressure turbine cascade

et al. 2019

Applied Thermal Engineering

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Measurement and Prediction of Tip Leakage Losses in an Axial-Flow Transonic Turbine

Cited by 4 publications

References 16 publications

Aero-thermodynamic and chemical process interactions in an axial high-pressure turbine of aircraft engines

Aero-thermodynamic and chemical process interactions in an axial high-pressure turbine of aircraft engines

Investigation of Tip Leakage Effects in Transonic Flow Using a Parallel Unstructured Navier-Stokes Code

Influences of a multi-cavity tip on the blade tip and the over tip casing aerothermal performance in a high pressure turbine cascade

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