Experimental Study and Method of Sloshing Model Test Considering Gas-Liquid Density Ratio
- Yangjun Ahn (Seoul National University) | Yonghwan Kim (Seoul National University) | Sang-Yeob Kim (Ship & Offshore Technology Center, Korean Register)
- Document ID
- International Society of Offshore and Polar Engineers
- International Journal of Offshore and Polar Engineering
- Publication Date
- September 2019
- Document Type
- Journal Paper
- 257 - 268
- 2019. The International Society of Offshore and Polar Engineers
- sloshing, LNG, scaling laws, density ratio, gas mixture
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- 4 since 2007
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This paper presents a methodology and the results of sloshing model tests considering gas-liquid density ratio. Experiment materials of conventional sloshing model tests needed to be altered for more proper scaling. Experimental methods for handling alternative gas mixture were introduced to match the density ratio. The described methods were practical, and accurately estimated the density ratio in the model tank. To illustrate the effects of the density ratio, extensive regular tests had been conducted with two rectangular models by regular sinusoidal excitations: one for the impulse pressure comparison, and the other for the local flow comparison. Obvious effects of the density ratio had been investigated.
Sloshing in LNG carriers can lead to large impact loads on a containment system. It is important to assess these impact loads for the adequate design of the cargo containment systems. Because of the stochastic and highly nonlinear characteristics of sloshing, an experimental approach has been mainly used and recommended by ship classification societies (American Bureau of Shipping, 2006; Bureau Veritas, 2011; Det Norske Veritas, 2006; Lloyd’s Register, 2009). Methodologies and their developments have been illustrated by the classification societies and primary studies of Gervaise et al. (2009), Kuo et al. (2009), and Kim et al. (2012).
In the application of the experimental approach, scaling the experiment results in the actual design is one of the difficulties. This scaling issue of sloshing model tests has been extensively studied, but a complete conclusion has not been drawn. The Vaschy-Buckingham theorem is a fundamental idea, and many studies have been based on suggesting and identifying dimensionless numbers. Bass et al. (1980) explained that the global behavior of the fluids might be governed by Froude scaling, so that the ullage pressures could be Froude scaled. Local behavior, however, significantly affects sloshing loads on the cargo hold containment systems, and it does need different scaling laws.
|File Size||4 MB||Number of Pages||12|