From the wavelet analysis, sloshing energies are mainly distributed around the external excitation frequency and expanded to high frequencies under violent condition. Afterwards, average values of the wavelet spectra are extracted to do a quantitative study at various points. The evolutions of theoretical and experimental wavelet spectra are discussed and the corresponding Fourier spectrums are compared. It focuses on variations and distributions of the wavelet energy in elastic tanks.
Figures in flexiglass free#
Morlet wavelet transform is introduced to analyze the free surface elevations and sloshing pressures. Different excitation frequencies are considered with low-fill-depth and large amplitude. Hydroelastic effect of sloshing is studied through an experimental investigation.
The study can provide a theoretical reference for the prediction system of oil spill emergency. The deviation of the transverse oil velocity is much larger than that of the rising time and the vertical oil velocity.
In the rising process of the oil particles, the vertical velocity of the oil is mainly affected by the spilled discharge, and the transverse velocity is more dependent on the water velocity. The spilled discharge is the primary factor affecting the rising time of the oil particles. The rising process of the oil can be divided into three stages: full, dispersion and aggregation period. The spilled oil under water is mainly distributed in the form of the scattered particles with different sizes. The sensitivity study of the characteristic physical quantities to various factors are presented afterward. The influence of the water flow and the spilled discharge on the behavior of the spilled oil are analyzed from both qualitative and quantitative perspectives. The oil trajectory, velocity and the rising time to the surface are obtained through this system. By the non-contact optical measuring technology, an image acquisition and data analysis system is designed to explore the spilled mechanism and characteristic. The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed to the surface. It is suggested to consider the effect of the entrapped air on the determination of the slamming load for the design of super-large LNG tanks in the offshore engineering.Ī physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow. The existence of the air cavity leads to a significant reduction of the maximum slamming load and structural response but an increase in the pressure impulse in spatial distribution. Therefore, the impact mode is changed from liquid-direct impact to liquid-indirect impact. The results show that the air cavity plays a cushion role between free surface and elastic wall. Furthermore, both impact load and structural response are measured and studied in the spatial and temporal distribution under shallow-water condition. The evolution of free surface and the development of entrapped air are analyzed quantitatively.
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Thus, a series of experiments are designed and conducted in an elastic rectangular tank under shallow-water condition. Studying the effect of entrapped air on slamming load is essential to understand the air-free surface-elastic structure interaction. The free surface entrapping air may easily happen under shallow-water condition in the tank, which could result in structural local failure.
The liquid impact induced by slamming in the membrane-type tank is an important issue for the design of Floating Liquefied Natural Gas (FLNG) facilities.
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