Analysis of Brittle Target Fracture from a Subsonic Water Drop Impact

Rosenblatt, M.; Ito, Y. M.; Eggum, GE

doi:10.1520/stp35803s

Cited by 8 publications

(8 citation statements)

References 4 publications

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“…This picture of jetting is contrary to w hat has often been described in the drop-impact literature (even by the present authors). However, careful study of our photographic evidence and of plots of computer simulations (Rosenblatt et al 1979) support the view th a t the jetting motion is initially towards the target surface rather than tangential to it. The relief waves moving into the drop soon bring the high-pressure phase of the process to an end, with the additional development, which can be observed in the experiments of Camus (1971), th a t the crossing of the relief waves produce sufficient tensile stresses to initiate cavitation of the liquid.…”

mentioning

confidence: 68%

Studies of two-dimensional liquid-wedge impact and their relevance to liquid-drop impact problems

Field

Lesser

Dear

1985

Proc. R. Soc. Lond. A

108

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In the initial stage of liquid-drop impact, the contact region expands faster than the wave speed in the liquid. This causes compressible behaviour in the liquid, and high transient pressures. High-velocity jetting results when the wave motion in the liquid overtakes the expanding contact edge and moves up the free surface of the drop. The detailed pressure fields in this early time history of impact have been calculated by Lesser ( Proc . R . Soc . Lond . 377, 289 (1981)) for both two and three-dimensional liquid masses and for targets of finite admittance. An important result is that the edge pressures exceed the central ‘water-hammer’ pressure 3ρ 0 CU i and at the time of shock-detachment approach ca . 3ρ 0 CU i . At this stage the edge pressures, for both spherical drops and two-dimensional liquid wedges, depend only on the impact velocity and the instantaneous angle between the liquid and solid surfaces. This suggests that the essential features of the early stage of liquid impact can be usefully studied by producing impacts with two-dimensional liquid wedges, and predicted data for pressures, shock angles and velocities are presented. Experiments are described for producing impacts with preformed shapes by using water-gelatine mixtures and observing the impact events with high-speed photography. The results confirm the main features of the model and give information on edge pressures, jetting, cavitation in the liquid and the effect of the admittance of the solid. The relevance of the results to the damage and erosion of materials subjected to liquid impact is discussed. In particular, it is possible to explain the apparently low damage-threshold of some materials, the form of damage and its development with repeated impact. The study highlights the importance of the detailed surface geometry in the region of contact.

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mentioning

confidence: 68%

Studies of two-dimensional liquid-wedge impact and their relevance to liquid-drop impact problems

Field

Lesser

Dear

1985

Proc. R. Soc. Lond. A

108

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“…where the subscript s refers to the solid body variables. It is then concluded in several studies [62][63][64][65] that the impact pressure has spatial and temporal distribution in the impact zone, as well as a maximum peak value that occurs at a critical contact radius (r c ). The maximum peak value was seen to be more important than the full pressure distribution and many equations to quantify the maximum peak pressure were provided, such as Heymann's approximation [63]:…”

Section: Water Hammer Pressurementioning

confidence: 99%

“…The full temporal and spatial distribution of the impact pressure was provided by many numerical works [65][66][67][68][69], where some such as Rosenblatt et al [65] confirmed Heymann's approximation of the maximum peak pressure. Once the impact pressure is obtained, it is usually used as a boundary loading condition acting on the solid target.…”

Section: Water Hammer Pressurementioning

confidence: 99%

“…Then the characteristics of the impact pressure caused by droplet impact and the consequent temporal and spatial stress and strain fields in the solid are obtained. This has received considerable attention in the period between the 1960s and 1980s and many analytical and numerical models were developed, notably Blowers' analytical solution [64], Hwang [128], Rosenblatt [65,129], Adler [114], and Lesser [130]. A comprehensive review of the analytical and numerical efforts done to characterize the impact pressure distribution and stresses in the solid was reported by Lesser and Field [131].…”

Section: Erosion Model Formulation and Challengesmentioning

confidence: 99%

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Water Droplet Erosion of Wind Turbine Blades: Mechanics, Testing, Modeling and Future Perspectives

Ibrahim

Medraj

2019

Materials

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The problem of erosion due to water droplet impact has been a major concern for several industries for a very long time and it keeps reinventing itself wherever a component rotates or moves at high speed in a hydrometer environment. Recently, and as larger wind turbine blades are used, erosion of the leading edge due to rain droplets impact has become a serious issue. Leading-edge erosion causes a significant loss in aerodynamics efficiency of turbine blades leading to a considerable reduction in annual energy production. This paper reviews the topic of water droplet impact erosion as it emerges in wind turbine blades. A brief background on water droplet erosion and its industrial applications is first presented. Leading-edge erosion of wind turbine is briefly described in terms of materials involved and erosion conditions encountered in the blade. Emphases are then placed on the status quo of understanding the mechanics of water droplet erosion, experimental testing, and erosion prediction models. The main conclusions of this review are as follow. So far, experimental testing efforts have led to establishing a useful but incomplete understanding of the water droplet erosion phenomenon, the effect of different erosion parameters, and a general ranking of materials based on their ability to resist erosion. Techniques for experimentally measuring an objective erosion resistance (or erosion strength) of materials have, however, not yet been developed. In terms of modelling, speculations about the physical processes underlying water droplet erosion and consequently treating the problem from first principles have never reached a state of maturity. Efforts have, therefore, focused on formulating erosion prediction equations depending on a statistical analysis of large erosion tests data and often with a combination of presumed erosion mechanisms such as fatigue. Such prediction models have not reached the stage of generalization. Experimental testing and erosion prediction efforts need to be improved such that a coherent water droplet erosion theory can be established. The need for standardized testing and data representation practices as well as correlations between test data and real in-service erosion also remains urgent.

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“…Une approche monodimensionnelle du choc élastique du microjet contre la paroi opposée permet de donner l'ordre de grandeur de l'amplitude de l'onde de choc, selon la nature de la paroi -dans le fluide : [5]. L'échelle de temps caractéristi-que de cette onde est liée à la taille du microjet :…”

Section: With the Aim Ofgainingunclassified

Empreintes dues à l'implosion de bulles isolées : Etude paramétrique expérimentale

Dorey¹,

Nienaltowska

1988

La Houille Blanche

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Analysis of Brittle Target Fracture from a Subsonic Water Drop Impact

Cited by 8 publications

References 4 publications

Studies of two-dimensional liquid-wedge impact and their relevance to liquid-drop impact problems

Studies of two-dimensional liquid-wedge impact and their relevance to liquid-drop impact problems

Water Droplet Erosion of Wind Turbine Blades: Mechanics, Testing, Modeling and Future Perspectives

Empreintes dues à l'implosion de bulles isolées : Etude paramétrique expérimentale

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