The influence of aeration and compressibility on slamming loads during cone water entry

Elhimer, Mehdi; Jacques, Nicolas; Alaoui, Aboulghit El Malki; Gabillet, Céline

doi:10.1016/j.jfluidstructs.2016.12.012

Cited by 24 publications

(6 citation statements)

References 48 publications

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“…2019; Güzel & Korkmaz 2020), but also by modifying the near-surface region via, for example, aeration (Elhimer et al. 2017) or liquid jet-induced acceleration (Speirs et al. 2019 a ).…”

Section: Introductionmentioning

confidence: 99%

“…(Kornhauser 1964;May 1975;Seddon & Moatamedi 2006;Guillet et al 2020). Previous studies have shown that impact forces can be reduced not only through object geometry (McGehee, Hathaway & Vaughan 1959;Thompson 1965;Li & Sigimura 1967;May 1970;Qi et al 2016;Sharker et al 2019;Güzel & Korkmaz 2020), but also by modifying the near-surface region via, for example, aeration (Elhimer et al 2017) or liquid jet-induced acceleration (Speirs et al 2019a). An interesting extension to the idea of free surface modification is to launch a precursory object to agitate the free surface before entry.…”

Section: Introductionmentioning

confidence: 99%

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Impact force reduction by consecutive water entry of spheres

et al. 2021

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“…2019; Güzel & Korkmaz 2020), but also by modifying the near-surface region via, for example, aeration (Elhimer et al. 2017) or liquid jet-induced acceleration (Speirs et al. 2019 a ).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact force reduction by consecutive water entry of spheres

et al. 2021

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“…Similar results are shown in the work of Bredmose et al 16 who also developed a numerical model to simulate this violent flow and capture the shock wave after impact. Moreover, the impact load of a plate and a cone into pure and aerated water is studied respectively by Ma et al 14 and Elhimer et al 17 The necessity of taking the compressibility into account is proved by their work. Despite the influence of aeration effect on the maximum impact load is confirmed, there are still some issues to be studied further.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical study on hydrodynamic impact of a disk in pure and aerated water

Hong

Wang

Liu

2020

Proceedings of the Institution of Mechanical Engineers, Part M:

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The hydrodynamic loads of a disk impacting pure and aerated water are investigated experimentally and numerically. Experiments are performed on a rigid disk with different aeration levels and focus on the spatial and temporal pressure distribution. Drop tests are conducted by a specially designed apparatus to prevent the variation of velocity during the slamming period. A specially designed bubble generator, able to adjust the void fraction, is utilized to generate uniform and tiny bubbles. A high-speed camera is utilized to record the water spray and splash curtain. A homemade compressible multiphase solver based on the reduced five equation model is adopted to evaluate the impact loads, which assumes the water and bubbles sharing the same velocity and pressure. The results show that bubbles in the water have a significant influence on the impact loads. As the void fraction increases from zero to nearly 1%, the peak impact pressure is reduced considerably and the impact duration is becoming obviously longer. In aerated water impact, the disk has a more uniform pressure distribution on the surface. However, the pressure impulse in aerated impact tests is basically unchanged compared with that in pure water.

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“…Reducing this peak impact force is of significant interest because it presents structural failure risk to impinging bodies like aircraft landing on water, water landing spacecraft, underwater missiles, divers, base jumpers, etc., (Kornhauser 1964;May 1975;Seddon & Moatamedi 2006;Guillet et al 2020). Previous studies have shown that impact forces can be reduced not only through object geometry (McGehee et al 1959;Thompson 1965;Li & Sigimura 1967;May 1970;Qi et al 2016;Sharker et al 2019;Güzel & Korkmaz 2020), but also by modifying the near-surface region via, for example, aeration (Elhimer et al 2017) or liquid jet-induced acceleration (Speirs et al 2019a). An interesting extension to the idea of free surface modification is to launch a precursory object to agitate the free surface before entry.…”

Section: Introductionmentioning

confidence: 99%

Impact force reduction by consecutive water entry of spheres

Rabbi,

Speirs,

Kiyama

et al. 2020

Preprint

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Free-falling objects impacting onto water pools experience a very high initial impact force, greatest at the moment when breaking through the free surface. Many have intuitively wondered whether throwing another object in front of an important object (like oneself) before impacting the water surface may reduce this high impact force. Here, we test this idea experimentally by allowing two spheres to consecutively enter the water and measuring the forces on the trailing sphere. We find that the impact acceleration reduction on the trailing sphere depends on the dynamics of the cavity created by the first sphere and the relative timing of the second sphere impact. These combined effects are captured by the non-dimensional 'Matryoshka' number, which classifies the observed phenomena into four major regimes. In three of these regimes, we find that the impact acceleration on the second sphere is reduced by up to 78% relative to impact on a quiescent water surface. Surprisingly, in one of the regimes the force on the trailing sphere is dramatically increased by more than 400% in the worst case observed. We explain how the various stages of cavity evolution result in the observed alterations in impact force in this multi-body water entry problem.

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The influence of aeration and compressibility on slamming loads during cone water entry

Cited by 24 publications

References 48 publications

Impact force reduction by consecutive water entry of spheres

Impact force reduction by consecutive water entry of spheres

Experimental and numerical study on hydrodynamic impact of a disk in pure and aerated water

Impact force reduction by consecutive water entry of spheres

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