Effects of droplet shape on impact force of low-speed droplets colliding with solid surface

Zhang, Ruizi; Zhang, Bin; Liu, Qian; Li, Jingyin; Guo, Penghua

doi:10.1007/s00348-019-2712-7

Cited by 35 publications

(13 citation statements)

References 35 publications

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“…Following are the LE structural response parameters that are used to quantify LEE damage: (1) peak impact forces (F imp ), (b) water hammer pressure (p wh ), and (c) damage erosion rate (D i )(Figure 3). The F imp on the blade's leading edge is given by an analytical model developed by [30,31]. The analytical model is verified in our previous work [22] and F imp is given as:…”

Section: Droplet Impact Responses and Associated Lee Damage Rate ( ḋI )mentioning

confidence: 74%

Leading Edge Erosion of Wind Turbine Blades: Effects of Environmental Parameters on Impact Velocities and Erosion Damage Rate

Verma

Jiang

Ren

et al. 2020

Volume 9: Ocean Renewable Energy

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Leading edge erosion (LEE) of a wind turbine blade (WTB) is a complex phenomenon that contributes to high operation and maintenance costs. The impact between rain droplets and rotating blades exerts cyclic fatigue stresses on the leading edge — causing progressive material loss and reduced aerodynamic performance. One of the most important parameters for erosion modelling and damage prediction is the relative impact velocity between rain droplets and rotating blade and depends upon the environmental conditions. The environmental condition, in general, could vary for onshore and offshore wind turbines (OWTs) — for instance, the presence of wave-induced loads along with less turbulent wind and varying rainfall conditions in the offshore environment. The present paper tries to provide guidelines whether all these parameters need to be included for LEE modelling. Aero-hydro-servo-elastic simulations are carried out for a rotating blade based on the NREL 5 MW turbine by considering realistic environmental conditions for a land-based wind turbine and monopile-supported OWT. Further, the impact velocities and erosion damage rate, evaluated using a surface fatigue model, are analysed and compared for different environmental conditions. It is found that rainfall intensity and turbulence intensity influences the impact velocity minorly, however, has a substantial effect on the overall erosion damage rate. For instance, for the investigated load cases, an 8% increase in the impact velocity is observed when the turbulence intensity increases from 6% to 26%, which indicates an increase of erosion damage rate by more than 40%. Furthermore, no substantial influence is found due to the effects of wave-induced loads on the wind turbine.

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Section: Droplet Impact Responses and Associated Lee Damage Rate ( ḋI )mentioning

confidence: 74%

Leading Edge Erosion of Wind Turbine Blades: Effects of Environmental Parameters on Impact Velocities and Erosion Damage Rate

Verma

Jiang

Ren

et al. 2020

Volume 9: Ocean Renewable Energy

View full text Add to dashboard Cite

show abstract

“…The following are the LE structural response parameters that are used to quantify LEE damage: (a) peak impact forces (F imp ), (b) water hammer pressure (p wh ), and (c) erosion damage rate (D i ) (Figure 4). The F imp on the blade's leading edge is given by an analytical model developed by [30,31]. The analytical model is verified in our previous work for wind turbine blades [20], and F imp is given as:…”

Section: Relative Impact Velocity Between Rain Droplets and The Rotating Blade ( V Imp )mentioning

confidence: 87%

Effects of Onshore and Offshore Environmental Parameters on the Leading Edge Erosion of Wind Turbine Blades: A Comparative Study

Verma

Jiang

Ren

et al. 2021

Journal of Offshore Mechanics and Arctic Engineering

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The presence of rain-induced leading edge erosion of wind turbine blades (WTBs) necessitates the development of erosion models. One of the essential parameters for erosion modeling is the relative impact velocity between rain droplets and the rotating blade. Based on this parameter, the erosion damage rate of a WTB is calculated to estimate the expected leading edge lifetime. The environmental conditions that govern this parameter have site-specific variations, and thus, rain and wind loading on a turbine differ for onshore and offshore locations. In addition, there are wave loads present in the offshore environment. The present paper tries to provide guidelines for erosion modeling and investigates whether there are differences in erosion of blades due to (1) varying rainfall conditions modeled using different droplet size distributions for onshore and offshore locations in combination with (2) winds of varying turbulence intensities and (3) wave-induced loads. Aero-hydro-servo-elastic simulations are carried out for an onshore wind turbine (WT) and a monopile-supported offshore WT. Furthermore, erosion variables such as the relative impact velocities and the associated erosion damage rate of a blade are analyzed for various blade azimuth angles. The study shows that the rainfall intensity and turbulence intensity minorly influence the impact velocity and pressure but have a substantial effect on the overall erosion damage rate. Additionally, a significantly higher erosion damage rate is found for blades exposed to offshore rainfall conditions than for blades under onshore rainfall conditions. Furthermore, no substantial influence on erosion is found because of wave-induced loads.

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“…Anantharamaiah et al 20 and Sanada et al 21 studied the influence of jet geometry on impact pressure, and found that the characteristics of the shock wave are related to the shape of the spherical droplet. Zhang 22 studied the dynamic characteristics of low-speed droplet hitting solid surface by the finite element method, and obtained the generation and expansion of water jet peening and the transient characteristics of water hammer pressure. However, the water jet peening they studied does not involve the impact pressure distribution on different cross sections of the flow field.…”

Section: Introductionmentioning

confidence: 99%

“…When the water jet vertically acts on the surface of the object, the impact pressure changes with the distance to the nozzle and spreads from the jet center to the surrounding. [23][24][25][26][27][28] Therefore, it is the scientific basis and key to establish an accurate calculation formula to describe the impact pressure distribution of the elliptical nozzle in order to realize the highefficiency treatment of high pressure water jet in engineering application. Song et al 29 studied the influence of the orifice flow geometry on the trajectory of the jet liquid column through experiments.…”

Section: Introductionmentioning

confidence: 99%

A new calculation formula to describe the dynamic pressure of water jet peening with elliptical nozzle for high-efficiency treatment

Zheng

Luo

Zhang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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Water jet peening is a good potential method to control welding residual stresses. The water jet with elliptical nozzle can improve the treatment efficiency due to its large treatment area. In this article, the water jet velocity and dynamic pressure for different elliptical nozzle dimensions and standoff distances are discussed by numerical simulation. The results show that when the axial distance is 10 mm, the effective impact diameter of the elliptical nozzle a/b=8–12 is about 2 times or more than that of the circular nozzle. The length of the jet core of the elliptical nozzle is only related to the outlet structure and is independent of the inlet pressure. The correlation between the dimensionless core length of the elliptical water jet and its long and short axes is derived. When the ratio of the major axis to the minor axis is between 7 and 13, the core length of the elliptical water jet is 7–7.5 times that of its minor axis. Combining the suitable treatment area and dynamic pressure, the elliptical nozzle with an axis ratio of 8 is recommended to control the welding residual stress. Finally, a new formula for calculating dynamic pressure distribution is proposed for the elliptical nozzle water jet at different stages.

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Effects of droplet shape on impact force of low-speed droplets colliding with solid surface

Cited by 35 publications

References 35 publications

Leading Edge Erosion of Wind Turbine Blades: Effects of Environmental Parameters on Impact Velocities and Erosion Damage Rate

Leading Edge Erosion of Wind Turbine Blades: Effects of Environmental Parameters on Impact Velocities and Erosion Damage Rate

Effects of Onshore and Offshore Environmental Parameters on the Leading Edge Erosion of Wind Turbine Blades: A Comparative Study

A new calculation formula to describe the dynamic pressure of water jet peening with elliptical nozzle for high-efficiency treatment

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