Numerical investigation of rain droplet impact on offshore wind turbine blades under different rainfall conditions: A parametric study

Verma, Amrit Shankar; Castro, Saullo G.P.; Jiang, Zhiyu; Teuwen, Julie J.E.

doi:10.1016/j.compstruct.2020.112096

Cited by 56 publications

(50 citation statements)

References 30 publications

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“…Majority of the misalignment occurs till 30°, with frequency being less than 5% for wind-wave misalignment greater than 60° ( Bachynski et al 2014). Currently, there are limited published literature sources (Jiang et al 2018;Verma et al 2019c;Verma et al 2019d;Verma et al 2020a;Verma et al 2020b) dealing with the effects of wind-wave misalignment on the installation phases of OWTs, although several studies in the past emphasised operational and parked conditions of OWTs for design purposes. Barj et al (2014), Bachynski et al (2014) and Zhou et al (2017) investigated the effect of misalignment on the operational loads for floating OWTs, whereas Fischer et al (2011) investigated the effect of misalignment on monopile-type OWTs.…”

Section: Article Highlightsmentioning

confidence: 99%

Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment

Verma

Jiang

Ren

et al. 2020

J. Marine. Sci. Appl.

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Most wind turbine blades are assembled piece-by-piece onto the hub of a monopile-type offshore wind turbine using jack-up crane vessels. Despite the stable foundation of the lifting cranes, the mating process exhibits substantial relative responses amidst blade root and hub. These relative motions are combined effects of wave-induced monopile motions and wind-induced blade root motions, which can cause impact loads at the blade root’s guide pin in the course of alignment procedure. Environmental parameters including the wind-wave misalignments play an important role for the safety of the installation tasks and govern the impact scenarios. The present study investigates the effects of wind-wave misalignments on the blade root mating process on a monopile-type offshore wind turbine. The dynamic responses including the impact velocities between root and hub in selected wind-wave misalignment conditions are investigated using multibody simulations. Furthermore, based on a finite element study, different impact-induced failure modes at the blade root for sideways and head-on impact scenarios, developed due to wind-wave misalignment conditions, are investigated. Finally, based on extreme value analyses of critical responses, safe domain for the mating task under different wind-wave misalignments is compared. The results show that although misaligned wind-wave conditions develop substantial relative motions between root and hub, aligned wind-wave conditions induce largest impact velocities and develop critical failure modes at a relatively low threshold velocity of impact.

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Section: Article Highlightsmentioning

confidence: 99%

Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment

Verma

Jiang

Ren

et al. 2020

J. Marine. Sci. Appl.

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“…The damage is in fact a 3D dynamic consequence resulting in the propagation of shock waves [3,4]. The droplet numerical modelling has been broadly studied by different authors [5][6][7][8]. As the water droplet impinges on the surface, a longitudinal compressional normal stress wave front in the top surface material further advances towards the coating-substrate interface, where a portion of the stress wave is reflected back into the coating with a different amplitude (depending on the relative material acoustic impedance) and yields a transverse shear wave.…”

Section: Introductionmentioning

confidence: 99%

“…This simplification is applicable since shear stresses and shear material characterization directly related with other important damage mechanisms as peeling, debonding, delamination or crack evolution are out of the wear fatigue analysis case involved. The analysis (or design) of Leading-Edge Protection systems depends on the material properties in the configuration and the operational load to which it is designed during its realistic life, that is, it must be able to withstand accelerated loads and also fatigue field regimes [6,9]. To make a selection or design of a specific coating protection system, appropriate modelling requires to be defined [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 1: Modelling Approach

Doménech

Renau

Šakalytė³

et al. 2020

Coatings

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Top coating are usually moulded, painted or sprayed onto the wind blade Leading-Edge surface to prevent rain erosion due to transverse repeated droplet impacts. Wear fatigue failure analysis based on Springer model has been widely referenced and validated to quantitatively predict damage initiation. The model requires liquid, coating and substrate speed of sound measurements as constant input parameters to define analytically the shockwave progression due to their relative vibro-acoustic properties. The modelling assumes a pure elastic material behavior during the impact event. Recent coating technologies applied to prevent erosion are based on viscoelastic materials and develop high-rate transient pressure build-up and a subsequent relaxation in a range of strain rates. In order to analyze the erosion performance by using Springer model, appropriate impedance characterization for such viscoelastic materials is then required and represents the main objective of this work to avoid lack of accuracy. In the first part of this research, it is proposed a modelling methodology that allows one to evaluate the frequency dependent strain-stress behavior of the multilayer coating system under single droplet impingement. The computational tool ponders the operational conditions (impact velocity, droplet size, layer thickness, etc) with the appropriate variable working frequency range for the speed of sound measurements. The second part of this research defines in a complementary paper, the ultrasonic testing characterization of different viscoelastic coatings and the methodology validation. The modelling framework is then used to identify suitable coating and substrate combinations due to their acoustic matching optimization and to analyze the anti-erosion performance of the coating protection system.

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“…In order to identify suitable coating and composite substrate combinations based on their potential stress reduction on the surface and interface different studies are related with the droplet impact phenomena [9,10]. Recent studies treat the complexity of the single droplet impact problem with the fatigue analysis under repeated impact [11], and considering material viscoelastic approaches [12][13][14]. The Springer [4] model is applied and industry validated [5] for wear top-coating rain erosion lifetime assessment.…”

Section: Introductionmentioning

confidence: 99%

Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 2: Material Characterization and Rain Erosion Testing Evaluation

Doménech

García-Peñas

Šakalytė³

et al. 2020

Coatings

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Under droplet impingement, surface leading edge protection (LEP) coating materials for wind turbine blades develop high-rate transient pressure build-up and a subsequent relaxation in a range of strain rates. The stress-strain coating LEP behavior at a working frequency range depends on the specific LEP and on the material and operational conditions, as described in this research in a previous work. Wear fatigue failure analysis, based on the Springer model, requires coating and substrate speed of sound measurements as constant input material parameters. It considers a linear elastic response of the polymer subjected to drop impact loads, but does not account for the frequency dependent viscoelastic effects for the materials involved. The model has been widely used and validated in the literature for different liquid impact erosion problems. In this work, it is shown the appropriate definition of the viscoelastic materials properties with ultrasonic techniques. It is broadly used for developing precise measurements of the speed of sound in thin coatings and laminates. It also allows accurately evaluating elastic moduli and assessing mechanical properties at the high frequencies of interest. In the current work, an investigation into various LEP coating application cases have been undertaken and related with the rain erosion durability factors due to suitable material impedance definition. The proposed numerical procedures to predict wear surface erosion have been evaluated in comparison with the rain erosion testing, in order to identify suitable coating and composite substrate combinations. LEP erosion performance at rain erosion testing (RET) technique is used widely in the wind industry as the key metric, in an effort to assess the response of the varying material and operational parameters involved.

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Numerical investigation of rain droplet impact on offshore wind turbine blades under different rainfall conditions: A parametric study

Cited by 56 publications

References 30 publications

Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment

Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment

Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 1: Modelling Approach

Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 2: Material Characterization and Rain Erosion Testing Evaluation

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