Vortex-Wake-Blade Interaction in a Shrouded Axial Turbine

Schlienger, J.; Kalfas, A. I.; Abhari, Reza S.

doi:10.1115/1.1934263

Cited by 37 publications

(11 citation statements)

References 12 publications

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“…This probe is a modified version of the conventional single sensor probe already used in previous investigations [16][17][18] and has a second sensor sensitive of pitch angle variation of the flow. The dimensions of each piezoresistive sensor are 0:4 0:8 mm, the distance between the two sensors is approximately 2.2 mm and the tip diameter of the probe is 1.8 mm.…”

Section: B Measurement Technologymentioning

confidence: 99%

See 1 more Smart Citation

Turbulence Measurements and Analysis in a Multistage Axial Turbine

Porreca

Hollenstein

Kalfas

et al. 2007

Journal of Propulsion and Power

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This paper presents turbulence measurements and detailed flow analysis in an axial turbine stage. Fast response aerodynamic probes were used to resolve aperiodic fluctuations along the three directions. Assuming incompressible flow, the effective turbulence level and Reynolds stress are retrieved by evaluating the stochastic velocity component out of the measured time-resolved pressure and flow angle fluctuations along the streamwise, radial, and circumferential direction. A comparison between turbulence intensity and measured total pressure shows that flow structures with higher turbulence level are identified in the region of loss cores at the exit of the second stator passage. Turbulence intensity is evaluated under isotropic and nonisotropic assumption in order to quantify the departure from isotropic conditions. The measurements show that locally the streamwise fluctuating component can be twice bigger than the radial and tangential component. The current analysis shows that multisensor fast response aerodynamic probes can be used to provide information about the mean turbulence levels in the flow and the Reynolds stress tensor, in addition to the measurements of unsteady total pressure loss. Nomenclature c = absolute velocity vector e = mean unit vector in the secondary flow definition p = static pressure p d = dynamic head s, , r = streamwise, circumferential, and radial directions T=T 0 = blade passing period fraction t = time u = streamwise velocity component u,ṽ,w = periodic velocity component: phase-lock averaged u 0 , v 0 , w 0 = stochastic (aperiodic) velocity components v = circumferential velocity component w = radial velocity component = yaw angle = pitch angle x = absolute uncertainty of quantity x = density Subscripts/superscripts 1 = probe position 1 iso = isotropic assumption NS = nonsimultaneous sec = secondary flow vector

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Section: B Measurement Technologymentioning

confidence: 99%

“…This paper follows a series of studies on unsteady flows in a multistage environment, conducted on the same shrouded turbine geometry and focused on blade interaction [16][17][18][19]. A methodology is proposed to derive turbulence quantities along the three spatial directions.…”

mentioning

confidence: 99%

Turbulence Measurements and Analysis in a Multistage Axial Turbine

Porreca

Hollenstein

Kalfas

et al. 2007

Journal of Propulsion and Power

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“…2. The overall average of the discharge angle evaluated on the whole downstream plane [17] or the radial distribution of the pitchwise averaged outlet angle has also been applied. 3.…”

Section: The Casing Boundary Layer Cannot Be Consideredmentioning

confidence: 99%

On the definition of the secondary flow in three-dimensional cascades

Persico

Gaetani

Dossena

et al. 2009

Proceedings of the Institution of Mechanical Engineers, Part A:

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The present article proposes a novel methodology to evaluate secondary flows generated by the annulus boundary layers in complex cascades. Unlike two-dimensional (2D) linear cascades, where the reference flow is commonly defined as that measured at midspan, the problem of the reference flow definition for annular or complex 3D linear cascades does not have a general solution up to the present time. The proposed approach supports secondary flow analysis whenever exit streamwise vorticity produced by inlet endwall boundary layers is of interest. The idea is to compute the reference flow by applying slip boundary conditions at the endwalls in a viscous 3D numerical simulation, in which uniform total pressure is prescribed at the inlet. Thus the reference flow keeps the 3D nature of the actual flow except for the contribution of the endwall boundary layer vorticity. The resulting secondary field is then derived by projecting the 3D flow field (obtained from both an experiment and a fully viscous simulation) along the local reference flow direction; this approach can be proficiently applied to any complex geometry. This method allows the representation of secondary velocity vectors with a better estimation of the vortex extension, since it offers the opportunity to visualize also the region of the vortices, which can be approximated as a potential type. Furthermore, a proficient evaluation of the secondary vorticity and deviation angle effectively induced by the annulus boundary layer is possible. The approach was preliminarily verified against experimental data in linear cascades characterized by cylindrical blades, not reported for the sake of brevity, showing a very good agreement with the standard methodology based only on the experimental midspan flow field. This article presents secondary flows obtained by the application of the proposed methodology on two annular cascades with cylindrical and 3D-designed blades, stressing the differences with other definitions. Both numerical and experimental results are considered.

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“…Last but not least, it provides total and static pressure measurements, which can be used for the evaluation of the blade-row and stage performance. Thanks to the very high temporal resolution, these probes also allowed to investigate experimentally the complex flow phenomena connected to unsteady blade row interaction [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Technology Development of Fast-Response Aerodynamic Pressure Probes

Gaetani

Persico

2020

IJTPP

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This paper presents and discusses the recent developments on the Fast-Response Aerodynamic Pressure Probe (FRAPP) technology at the Laboratorio di Fluidodinamica delle Macchine (LFM) of the Politecnico di Milano. First, the different geometries developed and tested at LFM are presented and critically discussed: the paper refers to single-sensor or two-sensor probes applied as virtual 2D or 3D probes for phase-resolved measurements. The static calibration of the sensors inserted inside the head of the probes is discussed, also taking into account for the temperature field of application: in this context, a novel calibration procedure is discussed and the new manufacturing process is presented. The dynamic calibration is reconsidered in view of the 15-years’ experience, including the extension to probes operating at different temperature and pressure levels with respect to calibration. As for the probe aerodynamics, the calibration coefficients are discussed and the most reliable set here is evidenced. A novel procedure for the quantification of the measurement uncertainty, recently developed and based on the Montecarlo methodology, is introduced and discussed in the paper.

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Vortex-Wake-Blade Interaction in a Shrouded Axial Turbine

Cited by 37 publications

References 12 publications

Turbulence Measurements and Analysis in a Multistage Axial Turbine

Turbulence Measurements and Analysis in a Multistage Axial Turbine

On the definition of the secondary flow in three-dimensional cascades

Technology Development of Fast-Response Aerodynamic Pressure Probes

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