Investigation of Laminar–Turbulent Transition on a Rotating Wind-Turbine Blade of Multimegawatt Class with Thermography and Microphone Array

Reichstein, Torben; Schaffarczyk, A. P.; Dollinger, Christoph; Balaresque, Nicolas; Schülein, Erich; Jauch, Clemens; Fischer, Andreas

doi:10.3390/en12112102

Cited by 32 publications

(38 citation statements)

References 26 publications

(32 reference statements)

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“…Since the chordwise surface temperature gradient is indicative of the state of the boundary layer [30], [34], we have used the second derivative of the temperature distribution to identify the presence of significant above measurement noise inflexion points which are related to events in the aerodynamic behavior of the boundary layer [20], [23], [24], [35].…”

Section: Measurements and Post-processingmentioning

confidence: 99%

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Laminar-Turbulent Transition on a Cambered NACA 16-009 Airfoil at Low Speed

Marinus

Vercauteren

Vandenberghe

et al. 2020

IREME

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Infrared thermography, force measurements, and oil flow visualizations are used to investigate the flow patterns around a cambered NACA16-409 airfoil at low Mach number. This cambered profile is widely used for propellers despite the lack of knowledge concerning its flow characteristics. The post-processing of thermograms relies on the analysis of the surface temperature gradient and identification of inflexion points in the temperature distribution. The observations made on the thermograms, based on the distribution of the temperature and Stanton number, are substantiated by the oil flow visualizations. RANS simulations with a transitional SST k-ω & γ turbulence model corroborate the analysis and deliver detailed insight in the flow around the airfoil. Depending on the angle of attack, three distinct flow patterns have been identified: laminar flow with early separation, laminar separation bubble with trailing edge separation, and turbulent flow with trailing edge separation. The shift between the last two regimes occurs sharply. The prediction capability of the transitional RANS simulations and XFOIL in terms of separation as well as reattachment location are compared with the experimental results. The force-coefficients dependency on the angle-of-attack, obtained by experiments, XFOIL, and RANS simulations, bear the traces from these flow patterns.

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Section: Measurements and Post-processingmentioning

confidence: 99%

“…These techniques range from simple contrast-based algorithms to differential analysis of a sequence of images in space [16], [18]- [20], [26], [33] or time [25].…”

Section: Introductionmentioning

confidence: 99%

Laminar-Turbulent Transition on a Cambered NACA 16-009 Airfoil at Low Speed

Marinus

Vercauteren

Vandenberghe

et al. 2020

IREME

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“…In addition to the DAN-AERO experimental campaign (Madsen et al, 2010) (Troldborg et al, 2013), of which the current analysis is based on, there have been other field experiments on boundary layer transition on rotating wind turbine blades using microphones glued on the surface (Van Ingen and Schepers, 2012), hot film and pressure tubes (Schwab et al, 2014) (Schaffarczyk et al, 2017), microphones on the suction side in addition to the ground based thermographic cameras (Reichstein et al, 2019). All these experiments pointed to a fact that more field experiments are needed on the wind turbine blades in order to characterize the transition behaviour with inflow turbulence and rotational effects.…”

Section: Introductionmentioning

confidence: 99%

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

Özçakmak¹,

Madsen²,

Sørensen³

et al. 2020

Preprint

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Abstract. Laminar-turbulent transition behaviour of a wind turbine blade section is investigated in this study by means of field experiments and 3-D computational fluid dynamics (CFD) rotor simulations. The power spectral density (PSD) integrals of the pressure fluctuations obtained from the high frequency microphones mounted on a blade section are analyzed to detect laminar-turbulent transition locations from the experiments. The atmospheric boundary layer (ABL) velocities and the turbulence intensities (T.I.) measured from the field experiments are used to create several inflow scenarios for the CFD simulations. Results from the natural and the bypass transition models of the in-house CFD EllipSys code are compared with the experiments. It is seen that the bypass transition model results fit well with experiments at the azimuthal positions where the turbine is under wake and high turbulence, while the results from other cases show agreement with the natural transition model. Furthermore, the influence of inflow turbulence, wake of an upstream turbine and angle of attack (AOA) on the transition behaviour is investigated through the field experiments. On the pressure side of the blade section, at high AOA values and wake conditions, variation of the transition location covers up to 44 % of the chord during one revolution, while for the no wake cases and lower AOA values, variation occurs along a region that covers only 5 % of the chord. The effect of the inflow turbulence on the effective angle of attack as well as its direct effect on transition is observed. Transition locations for the wind tunnel conditions and field experiments are compared together with 2D and 3D CFD simulations. In contrast to the suction side, significant difference in the transition locations is observed between wind tunnel and field experiments on the pressure side for the same airfoil geometry. It is seen that the natural and bypass transition models of EllipSys3D can be used for transition prediction of a wind turbine blade section for high Reynolds number flows by applying various inflow scenarios separately to cover the whole range of atmospheric occurrences.

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“…Envelope methods (Gleyzes et al, 1983;Drela and Giles, 1987) and approximate methods (Stock and Degenhart, 1989) were developed. The effect of disturbance environment on the transition process has been studied by Morkovin (1969) and Reshotko (1969).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the DAN-AERO experimental campaign (Madsen et al, 2010;Troldborg et al, 2013), on which the current analysis is based, there have been other field experiments on boundary layer transition on rotating wind turbine blades using microphones glued on the surface (Jan Leendert Van Ingen and J. Gerard Schepers, personal communication, 2020), hot film, pressure tubes (Schwab et al, 2014;, microphones on the suction side, and the ground-based thermographic cameras (Reichstein et al, 2019). All these experiments pointed to the fact that more field experiments are needed on the wind turbine blades in order to characterize the transition behavior with inflow turbulence and rotational effects.…”

Section: Introductionmentioning

confidence: 99%

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

Özçakmak¹,

Madsen

Sørensen³

et al. 2020

Wind Energ. Sci.

View full text Add to dashboard Cite

Abstract. Laminar-turbulent transition behavior of a wind turbine blade section is investigated in this study by means of field experiments and 3-D computational fluid dynamics (CFD) rotor simulations. The power spectral density (PSD) integrals of the pressure fluctuations obtained from the high-frequency microphones mounted on a blade section are analyzed to detect laminar-turbulent transition locations from the experiments. The atmospheric boundary layer (ABL) velocities and the turbulence intensities (T.I.) measured from the field experiments are used to create several inflow scenarios for the CFD simulations. Results from the natural and the bypass transition models of the in-house CFD EllipSys code are compared with the experiments. It is seen that the bypass transition model results fit well with experiments at the azimuthal positions where the turbine is under wake and high turbulence, while the results from other cases show agreement with the natural transition model. Furthermore, the influence of inflow turbulence, wake of an upstream turbine, and angle of attack (AOA) on the transition behavior is investigated through the field experiments. On the pressure side of the blade section, at high AOA values and wake conditions, variation in the transition location covers up to 44 % of the chord during one revolution, while for the no-wake cases and lower AOA values, variation occurs along a region that covers only 5 % of the chord. The effect of the inflow turbulence on the effective angle of attack as well as its direct effect on transition is observed. Transition locations for the wind tunnel conditions and field experiments are compared together with 2-D and 3-D CFD simulations. In contrast to the suction side, significant difference in the transition locations is observed between wind tunnel and field experiments on the pressure side for the same airfoil geometry. It is seen that the natural and bypass transition models of EllipSys3D can be used for transition prediction of a wind turbine blade section for high-Reynolds-number flows by applying various inflow scenarios separately to cover the whole range of atmospheric occurrences.

show abstract

Investigation of Laminar–Turbulent Transition on a Rotating Wind-Turbine Blade of Multimegawatt Class with Thermography and Microphone Array

Cited by 32 publications

References 26 publications

Laminar-Turbulent Transition on a Cambered NACA 16-009 Airfoil at Low Speed

Laminar-Turbulent Transition on a Cambered NACA 16-009 Airfoil at Low Speed

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

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