Abstract
Current offshore engineering design codes for wave loading are based on pure water, but wave impacts often involve aerated flow, either as a result of air entrapment as the wave overturns or due to impact with a wave that is already broken. Therefore, it is necessary to develop a new understanding of how design codes should incorporate water-air mixture for wave impact. This experimental study investigates aeration effects on wave impacts by means of slamming impacts of a square flat plate onto a pure and aerated water surface, with zero degree dead-rise angle. The (low) aeration level between 0% and 1.6% was applied and the drop velocity varied from about 1 m/s to 7 m/s. There was a significant reduction in the peak impact loads (both pressure and force) for impact in aerated water compared to that in pure water. There was also a significant reduction in the first phase of the pressure and force impulse for aerated water. The variation in impulsive loadings is less sensitive than peak loadings for impacts. The implication for design is that maximum instantaneous loads may be conservative in the presence of aerated water.
Highlights
Hydrodynamic impact problems are frequently encountered in marine engineering (Faltinsen, 1993 & 2000; Kapsenberg, 2011), water sports (Rubin, 1999) and natural hazards (Kay, 2014; Rodgers & Bryson, 2014)
The ditching of an aircraft on the water surface is another problem of water slamming on a body which can lead to damage to the aircraft and potential loss of life
The maximum acceleration due to the impact was not captured by the 200g accelerometer as the signal was clipped from the moment that the plate hit the water surface (Figure 3a)
Summary
Hydrodynamic impact problems are frequently encountered in marine engineering (Faltinsen, 1993 & 2000; Kapsenberg, 2011), water sports (Rubin, 1999) and natural hazards (Kay, 2014; Rodgers & Bryson, 2014). Von Kármán (1929) developed the first theory to estimate pure water impact for a wedge and for a horizontal plate. Several experimental studies have been undertaken to investigate water slamming by dropping a wedge (Chuang, 1966a; Zhu, 1995; Zhao et al, 1997), a horizontal-bottomed body (Chuang, 1966b; Verhagen, 1967; Zhu, 1995; Faltinsen, 2000; Bullock et al, 2001; Kwon et al, 2003; Ermanyuk et al, 2005; Oh et al, 2009), a horizontal circular cylinder (Lange and Rung, 2011; Van Nuffel et al, 2014) and a pyramid onto a still pure water surface (Alaoui et al, 2012 & 2015). Smith et al (1998) conducted a series of drop tests of a horizontal plate onto waves of different steepness
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
