Special Issue "Selected Papers from the 12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics (ETC12)"

A special issue of International Journal of Turbomachinery, Propulsion and Power (ISSN 2504-186X).

Deadline for manuscript submissions: closed (31 December 2017)

Special Issue Editor

Guest Editor
Prof. Marcello Manna

Dipartimento di Ingegneria Industriale, Università degli Studi di Napoli Federico II, via Claudio 21, 80125, Naples, Italy
Website | E-Mail
Phone: +39 (0)81-7683287
Fax: +39 (0)81.67.65.69
Interests: turbomachinery design systems; numerical methods; turbulence modelling; wind turbines; propellers

Special Issue Information

Dear Colleagues,

The 12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics (ETC 12) was held in April, 2017, in Stockholm (Sweden). The conference covered, from scientific and engineering perspectives, fluid dynamics and thermodynamics of turbomachines, as well as of turbomachinery-based propulsion systems and power systems.

In this Special Issue we are gathering the highest quality papers presented at the conference; a collection of excellent works of high interest to the turbomachinery community that showcase cutting-edge research in Europe.

Prof. Marcello Manna
Guest Editor

Published Papers (11 papers)

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Open AccessEditorial Excellence in Turbomachinery Research: The Best of the 12th European Turbomachinery Conference
Int. J. Turbomach. Propuls. Power 2018, 3(3), 19; https://doi.org/10.3390/ijtpp3030019
Received: 29 June 2018 / Accepted: 29 June 2018 / Published: 9 July 2018
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Research

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Open AccessArticle Numerical Investigation of Secondary Flow and Loss Development in a Low-Pressure Turbine Cascade with Divergent Endwalls
Int. J. Turbomach. Propuls. Power 2018, 3(1), 5; https://doi.org/10.3390/ijtpp3010005
Received: 7 December 2017 / Revised: 31 January 2018 / Accepted: 1 February 2018 / Published: 9 February 2018
Cited by 2 | PDF Full-text (1398 KB) | HTML Full-text | XML Full-text
Abstract
Secondary flow and loss development in the T106Div-EIZ low-pressure turbine cascade are investigated utilizing (U)RANS simulations in cases with and without periodically incoming wakes at Ma2th=0.59 and Re2th=2×
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Secondary flow and loss development in the T106Div-EIZ low-pressure turbine cascade are investigated utilizing (U)RANS simulations in cases with and without periodically incoming wakes at M a 2 t h = 0 . 59 and R e 2 t h = 2 × 10 5 . The predictions are compared to experimental data presented by Kirik and Niehuis (2015). The axial mid-span and overall loss development in the T106Div-EIZ and the T106A-EIZ in the steady case are analyzed regarding the effects caused by the different loading distributions and by the divergent endwall geometry. Furthermore, the entropy generation is analyzed in the T106Div-EIZ with periodically incoming wakes in several axial positions of interest and compared to the undisturbed steady case. It is found that in the front-loaded T106Div-EIZ, the incoming wakes cause a premature endwall loss production in the front part of the passage, resulting in a lower intensity of the secondary flow downstream of the passage and a redistribution of the loss generation components. Full article
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Open AccessArticle Simulation of Indexing and Clocking with Harmonic Balance
Int. J. Turbomach. Propuls. Power 2018, 3(1), 1; https://doi.org/10.3390/ijtpp3010001
Received: 9 November 2017 / Revised: 15 December 2017 / Accepted: 15 December 2017 / Published: 22 December 2017
Cited by 2 | PDF Full-text (2624 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this paper is to demonstrate how the harmonic balance method can be used to predict rotor–rotor and stator–stator interactions in turbomachinery. These interactions occur in the form of clocking and indexing. Whereas clocking refers to the dependency of the performance
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The aim of this paper is to demonstrate how the harmonic balance method can be used to predict rotor–rotor and stator–stator interactions in turbomachinery. These interactions occur in the form of clocking and indexing. Whereas clocking refers to the dependency of the performance on the relative circumferential positioning of the rotors or stators, the term indexing is used when different blade (or vane) counts lead to an aperiodic time-averaged flow. The approach developed here is closely related to the one presented by He, Chen, Wells, Li, and Ning, who generalised the Nonlinear Harmonic method to zero-frequency disturbances. In particular, configurations with only one passage per blade row are used for the simulations. We validate the methods by means of the simulation of a fan stage configuration with rotationally asymmetric inlet conditions. It is demonstrated that the harmonic balance solver is able to accurately predict the inhomogeneity of the time-averaged flow field in the stator row. Moreover, the results show that the approach offers a considerable gain in computational efficiency. Full article
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Open AccessArticle Parameterised Model of 2D Combustor Exit Flow Conditions for High-Pressure Turbine Simulations
Int. J. Turbomach. Propuls. Power 2017, 2(4), 20; https://doi.org/10.3390/ijtpp2040020
Received: 8 August 2017 / Revised: 3 November 2017 / Accepted: 4 December 2017 / Published: 8 December 2017
Cited by 1 | PDF Full-text (21259 KB) | HTML Full-text | XML Full-text
Abstract
An algorithm is presented generating a complete set of inlet boundary conditions for Reynolds-averaged Navier–Stokes computational fluid dynamics (RANS CFD) of high-pressure turbines to investigate their interaction with lean and rich burn combustors. The method shall contribute to understanding the sensitivities of turbine
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An algorithm is presented generating a complete set of inlet boundary conditions for Reynolds-averaged Navier–Stokes computational fluid dynamics (RANS CFD) of high-pressure turbines to investigate their interaction with lean and rich burn combustors. The method shall contribute to understanding the sensitivities of turbine aerothermal performance in a systematic approach. The boundary conditions are based on a set of input parameters controlling velocity, temperature, and turbulence fields. All other quantities are derived from operating conditions and additional modelling assumptions. The algorithm is coupled with a CFD solver by applying the generated profiles as inlet boundary conditions. The successive steps to derive consistent flow profiles are described and results are validated against flow fields extracted from combustor CFD. Full article
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Open AccessArticle The Effect of Hot Streaks on a High Pressure Turbine Vane Cascade with Showerhead Film Cooling
Int. J. Turbomach. Propuls. Power 2017, 2(3), 15; https://doi.org/10.3390/ijtpp2030015
Received: 10 May 2017 / Revised: 5 September 2017 / Accepted: 6 September 2017 / Published: 13 September 2017
Cited by 2 | PDF Full-text (9868 KB) | HTML Full-text | XML Full-text
Abstract
Hot streak migration in a linear vane cascade with showerhead film cooling was experimentally and numerically investigated at isentropic exit Mach number of Ma2is = 0.40, with an inlet turbulence intensity level of Tu1 = 9%. Two tangential positions of the
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Hot streak migration in a linear vane cascade with showerhead film cooling was experimentally and numerically investigated at isentropic exit Mach number of Ma2is = 0.40, with an inlet turbulence intensity level of Tu1 = 9%. Two tangential positions of the hot streak center were taken into account: 0% of pitch (hot streak is aligned with the vane leading edge) and 45% of pitch. After demonstrating that computations correctly predict hot streak attenuation through the vane passage with no showerhead blowing, the numerical method was used to investigate hot streak interaction with showerhead film cooling, at blowing ratio of BR = 3.0, corresponding to a coolant-to-mainstream mass flow ratio of MFR = 1.15%. The effects of mixing and coolant interaction on the hot streak reduction were interpreted under the light of the superposition principle, whose accuracy was within 12% on the leading edge region, in the central section of the vane span. Full article
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Open AccessArticle Influence of Pressure Fluctuations on the Mean Value of Different Pneumatic Probes
Int. J. Turbomach. Propuls. Power 2017, 2(3), 13; https://doi.org/10.3390/ijtpp2030013
Received: 20 March 2017 / Revised: 1 August 2017 / Accepted: 7 August 2017 / Published: 30 August 2017
Cited by 1 | PDF Full-text (3651 KB) | HTML Full-text | XML Full-text
Abstract
For this study, measurements were carried out in a one-and-a-half stage test turbine. In order to characterize the flow field and to obtain steady flow quantities, five-hole probes are used in the rig in several measurement planes. Although a very high resolution in
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For this study, measurements were carried out in a one-and-a-half stage test turbine. In order to characterize the flow field and to obtain steady flow quantities, five-hole probes are used in the rig in several measurement planes. Although a very high resolution in circumferential and radial direction is possible with five-hole probes, only certain sectors of the flow field can be measured due to quite long measurement times. For this reason, total pressure rakes, which can be traversed 360 degrees in a circumferential direction, were built for this test configuration. During foregoing measurements, differences between the total pressure measured with the rakes and the total pressure measured with a five-hole probes were observed, especially in the measurement plane downstream of the rotor where the flow is highly unsteady. It was found that the measured value for total pressure is particularly influenced by the stochastic pressure fluctuations and turbulence and can therefore deviate significantly from the “real” value. Full article
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Open AccessArticle Adjoint-Based Design Optimisation of an Internal Cooling Channel U-Bend for Minimised Pressure Losses
Int. J. Turbomach. Propuls. Power 2017, 2(2), 10; https://doi.org/10.3390/ijtpp2020010
Received: 26 May 2017 / Revised: 26 May 2017 / Accepted: 2 June 2017 / Published: 21 June 2017
Cited by 3 | PDF Full-text (4295 KB) | HTML Full-text | XML Full-text
Abstract
The success of shape optimisation depends significantly on the parametrisation of the shape. Ideally, it defines a very rich variation in shape, allows for rapid grid generation of high quality, and expresses the shape in a standard Computer Aided Design (CAD) representation. While
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The success of shape optimisation depends significantly on the parametrisation of the shape. Ideally, it defines a very rich variation in shape, allows for rapid grid generation of high quality, and expresses the shape in a standard Computer Aided Design (CAD) representation. While most existing parametrisation methods fail at least one of these criteria, this work introduces a novel parametrisation method, which satisfies all three. A tri-variate B-spline volume is used to define the volume to be optimised. The position of the external control points are used as design parameters, while the internal control points are repositioned to ensure regularity of the transformation. The grid generation process transforms a Cartesian grid (defined in parametric space) to the physical space using the tri-variate net of control points. This process guarantees a high grid quality even for large deformations, and has extremely low computational cost as it only involves a transformation from parameter space to physical space. This allows the computation of the grid sensitivities with respect to the design variables at a fraction of the cost of a Computational Fluid Dynamics (CFD) iteration, therefore allowing the use of one-shot methods. This novel parametrisation is applied to the shape optimisation of a U-bend passage of a turbine-blade serpentine-cooling channel with the objective to minimise pressure losses. A steady state, Reynolds-Averaged, density-based Navier-Stokes solver is used to predict the pressure losses at a Reynolds number of 40,000. The sensitivities of the objective function with respect to the control points are computed using a hand-derived adjoint solver and geometry generation system. A one-shot approach is used to simultaneously converge flow, gradient and design, resulting in a rapid design approach with a design time equivalent to approximately 10 normal CFD runs, while still maintaining a CAD representation of the geometry. A large reduction in pressure loss is obtained, and the flow in the optimal geometry is analysed in detail. Full article
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Open AccessArticle Effects of the Approximations Embodied in the Momentum Theory as Applied to the NREL PHASE VI Wind Turbine
Int. J. Turbomach. Propuls. Power 2017, 2(2), 9; https://doi.org/10.3390/ijtpp2020009
Received: 12 May 2017 / Revised: 6 June 2017 / Accepted: 6 June 2017 / Published: 15 June 2017
Cited by 5 | PDF Full-text (306 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates the impact of the standard approximations embodied in the well-known Momentum Theory on its performance prediction capabilities. To this aim, the results of the momentum theory, which is still widely used in all Blade Element/Momentum codes for the analysis and/or
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This paper investigates the impact of the standard approximations embodied in the well-known Momentum Theory on its performance prediction capabilities. To this aim, the results of the momentum theory, which is still widely used in all Blade Element/Momentum codes for the analysis and/or design of wind turbines, are compared with those obtained with an actuator disk model based on Computational Fluid Dynamics techniques. In this method, the axisymmetric and steady Euler equations are solved with a classical finite volume approach, while the turbine effects are modelled through a set of axial and tangential body forces distributed over a disk shaped region representing the rotor swept surface. Since this method does not rely on the momentum theory simplifying assumptions, it can be suitably employed to verify the momentum theory validity. The analysis is carried out using the well documented experimental data of the National Renewable Energy Laboratory Phase VI wind turbine. Full article
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Open AccessArticle Linear Stability Prediction of Vortex Structures on High Pressure Turbine Blades
Int. J. Turbomach. Propuls. Power 2017, 2(2), 8; https://doi.org/10.3390/ijtpp2020008
Received: 3 May 2017 / Revised: 16 May 2017 / Accepted: 22 May 2017 / Published: 26 May 2017
Cited by 2 | PDF Full-text (3279 KB) | HTML Full-text | XML Full-text
Abstract
Velocity profiles are extracted from time- and span-averaged direct numerical simulation data, describing the flow over a high-pressure turbine vane linear cascade near engine-scale conditions with reduced inlet disturbance levels. Based on these velocity profiles, local as well as non-local linear stability analysis
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Velocity profiles are extracted from time- and span-averaged direct numerical simulation data, describing the flow over a high-pressure turbine vane linear cascade near engine-scale conditions with reduced inlet disturbance levels. Based on these velocity profiles, local as well as non-local linear stability analysis of the boundary-layer over the suction side of the vane is carried out in order to characterise a linearly unstable region close to the trailing edge. The largest growth rates are found for oblique modes, but those are only slightly more unstable than 2D modes, which describe the locations and frequencies of most unstable modes very well. The frequencies of the most unstable linear modes predict with good accuracy the predominant frequencies found in the direct numerical simulations (DNS) close to the trailing edge. Full article
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Open AccessArticle Analysis of the Aerodynamic and Structural Performance of a Cooling Fan with Morphing Blade
Int. J. Turbomach. Propuls. Power 2017, 2(2), 7; https://doi.org/10.3390/ijtpp2020007
Received: 14 April 2017 / Revised: 15 May 2017 / Accepted: 16 May 2017 / Published: 23 May 2017
Cited by 1 | PDF Full-text (4025 KB) | HTML Full-text | XML Full-text
Abstract
The concept of smart morphing blades, which can control themselves to reduce or eliminate the need for active control systems, is a highly attractive solution in blade technology. In this paper, an innovative passive control system based on Shape Memory Alloys (SMAs) is
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The concept of smart morphing blades, which can control themselves to reduce or eliminate the need for active control systems, is a highly attractive solution in blade technology. In this paper, an innovative passive control system based on Shape Memory Alloys (SMAs) is proposed. On the basis of previous thermal and shape characterization of a single morphing blade for a heavy-duty automotive cooling axial fan, this study deals with the numerical analysis of the aerodynamic loads acting on the fan. By coupling computational fluid dynamics and finite element method approaches, it is possible to analyze the actual blade shape resulting from both the aerodynamic and centrifugal loads. The numerical results indicate that the polymeric blade structure ensures proper resistance and enables shape variation due to the action of the SMA strips. Full article
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Open AccessFeature PaperArticle Hot Streak Evolution in an Axial HP Turbine Stage
Int. J. Turbomach. Propuls. Power 2017, 2(2), 6; https://doi.org/10.3390/ijtpp2020006
Received: 24 March 2017 / Revised: 24 March 2017 / Accepted: 18 April 2017 / Published: 27 April 2017
Cited by 2 | PDF Full-text (7231 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the results of an experimental study on the evolution of hot streaks generated by gas turbine burners in an un-cooled high-pressure turbine stage. The prescribed hot streaks were directed streamwise and characterized by a 20% over-temperature with respect to the
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This paper presents the results of an experimental study on the evolution of hot streaks generated by gas turbine burners in an un-cooled high-pressure turbine stage. The prescribed hot streaks were directed streamwise and characterized by a 20% over-temperature with respect to the main flow at the stage inlet. The hot streak was injected in four different circumferential positions with respect to the stator blade. Detailed temperature and aerodynamic measurements upstream and downstream of the stage, as well as in-between the blade rows, were performed. Measurements showed a severe temperature attenuation of the hot streaks within the stator cascade; some influence on the aerodynamic field was found, especially on the vorticity field, while the temperature pattern resulted in severe alteration depending on the injection position. Downstream of the rotor, the jet spread over the pitch above the midspan and was more concentrated at the hub. Rotor secondary flows were also enhanced by hot streaks. Full article
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