Experimental Study of Coupling Vibration Characteristics Between a Thin Cylindrical Water Storage Tank and Its Contained Liquid

2005 ◽  
Author(s):  
Akira Maekawa ◽  
Yasutaka Shimizu ◽  
Michiaki Suzuki ◽  
Katsuhisa Fujita
Keyword(s):  
Storage Tank ◽  
Excitation Frequency ◽  
Fluid Pressure ◽  
Water Storage ◽  
Fem Analysis ◽  
Shaking Table ◽  
Vibration Modes ◽  
Coupled Vibration ◽  
Fluid Structure ◽  
Water Storage Tank

A large cylindrical water storage tank typically has a thin sidewall. When such a tank is under an earthquake, the vibrations of the water inside are coupled with the vibrations of the sidewall, producing a phenomenon called fluid-structure coupled vibration. The fluid-structure coupled vibration is an important issue for a tank like this to achieve reasonable seismic-proof design. Even though there have been many studies on fluid-structure coupled vibrations, only a few of them have examined the dynamic fluid pressure and oval vibrations. This paper reports on the investigations into the characteristics of oval vibrations exhibited by a cylindrical water storage tank, in which a vibration test was conducted using a shaking table, the correlation of changes in the excitation force and behaviors of dynamic fluid pressure with the appearance and growth of oval vibrations were analyzed, and the modes of oval vibrations that appeared were identified. The vibration test was conducted using a scale model tank of a large cylindrical water storage tank and a shaking table. The input vibrations were sinusoidal waves of 53 Hz, a frequency that was in the vicinity of the resonance frequency. The test took the form of a large amplitude excitation test, which increased the acceleration of the input vibrations gradually. The response acceleration of the tank and the dynamic fluid pressure were measured. Strain gages attached around the trunk of the tank were used to identify oval vibration modes. The frequency analysis of the dynamic fluid pressure revealed two major peaks, one at 53 Hz which matched the excitation frequency and the other at 106 Hz which was double the excitation frequency. It showed that the dynamic fluid pressure has nonlinear behavior like higher-harmonic resonance. The frequency analysis of the responses on the trunk of the tank arising from oval vibrations also revealed two major peaks, one at 53Hz and the other at 106Hz. The behavior of dynamic fluid pressure and the behavior of oval vibrations were coupled. It was found that a certain magnitude of the response acceleration of the tank that gave rise to oval vibrations were in proportion to the rate of increase of the response acceleration of the tank. In other words, oval vibrations appeared at a relatively low response acceleration if the response acceleration increased slowly, whereas oval vibrations appeared only at a relatively high response acceleration if the response acceleration increased quickly. An analysis of the circumferential distribution of circumferential strains around the trunk of the tank revealed the presence of two oval vibration modes with different circumferential wave numbers: 14 and 16, which have not been predicted by the FEM analysis. None of the natural frequencies determined by the FEM analysis of the two different vibration modes matched 106 Hz; however, a half of the sum of the two natural frequencies was close to 106 Hz. Thus oval vibrations were found to have a nonlinear characteristics experimentally.

Study of Correlation Between Beam Vibration and Oval Vibration on Cylindrical Water Storage Tank

2005 ◽  
Author(s):  
Akira Maekawa ◽  
Yasutaka Shimizu ◽  
Michiaki Suzuki ◽  
Katsuhisa Fujita
Keyword(s):  
Natural Frequency ◽  
Large Amplitude ◽  
Storage Tank ◽  
Excitation Frequency ◽  
Water Storage ◽  
Scale Model ◽  
Vibration Test ◽  
Large Radius ◽  
Water Storage Tank ◽  
Test Tank

A large cylindrical water storage tank, widely used at power stations and chemical plants, typically has a large radius/wall-thickness ratio. The relatively thin sidewall of such a tank can deform easily during an earthquake due to vibrations of the tank structure. In order to improve the seismic-proof design practices for a water storage tank of flexible structure and to develop a new seismic resistance evaluation method to be adopted in future, it is important to understand the dynamic responses of such a tank to seismic motions including the nonlinearity of responses to large amplitude vibrations. This paper reports on the results of vibration test, in which sinusoidal wave excitations with large amplitude were conduced to the scale model tank of a thin-walled cylindrical water storage tank, and the theoretical analysis of the dynamics of the vibratory behaviors that were observed during the vibration test. First, a frequency sweep test was performed over the range that covered the natural frequency. The response of the test tank as a whole to given vibrations remained almost the same over the excitation frequency range. Frequency analysis of the response of the tank failed to locate any resonance points at or around frequencies that had been determined by the basic vibration characteristic test that we had conducted in advance. Next, a large amplitude excitation tests were carried out, in which the test tank was excited intensively by several tens of sinusoidal waves of a fixed frequency that was in the vicinity of the resonant frequency. The response of the tank as a whole in the form of beam vibrations did not intensify in proportion to the input acceleration; it did not go beyond a certain level. Since both of the tests produced significant oval vibrations on the sidewall of tank, the influence of oval vibrations over beam vibrations was analyzed. The analysis concerning the deflection of the sidewall of tank by the additional appearance of oval vibrations in the presence of beam vibrations revealed that a major decrease in the flexural rigidity reduced the response (beam vibrations) of the whole tank. The phenomenon was modeled using a nonlinear equation of motion, assumed that the rigidity depended on the amplitude of oval vibrations. The analysis using this equation explained the results of the above-mentioned tests very well. Thus, it was demonstrated both empirically and analytically that beam vibrations of a cylindrical water storage tank are reduced by the appearance of oval vibrations that have the effect of lowering the natural frequency.

Vibration Test of 1/10 Scale Model of Cylindrical Water Storage Tank

2004 ◽  
Author(s):  
Akira Maekawa ◽  
Yasutaka Shimizu ◽  
Michiaki Suzuki ◽  
Katsuhisa Fujita
Keyword(s):  
Storage Tank ◽  
Large Scale ◽  
Seismic Waves ◽  
Fluid Pressure ◽  
Water Storage ◽  
Seismic Excitation ◽  
Scale Model ◽  
Vibration Test ◽  
Water Storage Tank ◽  
Circumferential Distribution

Large-scale cylindrical water storage tanks have a large ratio of radius to thickness, which means their thickness is relatively thin compared with the radius. Regarding seismic responses, the deformation of a tank frame is significantly influenced by the sloshing of the water inside the tank and by the bulging vibration of the tank structure, therefore it is important to consider such deformation theoretically and experimentally. This paper describes the results of a vibration test with a 1/10 reduced scale model of a large-scale industrial cylindrical water storage tank, conducted particularly to clarify the dynamic behavior of the tank during a seismic excitation. First a sinusoidal wave excitation experiment was performed for the scale model tank, which measured axial distributions of dynamic fluid pressures, strains and accelerations. Ovaling vibration of the scale model tank also was examined by measuring the circumferential distribution of strains. Furthermore, the dependence of dynamic fluid pressure on the acceleration magnitude of the input excitation was investigated. Secondly, a seismic excitation experiment was conducted using typical seismic waves. Finally, the measuring results were compared with the values calculated using common seismic-proof design methods based on the Housner method or velocity potential theory and the finite element method. Considering the differences between the experiment values and numerical design ones, it became obvious that there was inconsistent between the positive and the negative pressures of the dynamic fluid pressure and that the dynamic fluid pressure was dependent on the acceleration magnitude. And it was suggested that such phenomena were caused by ovaling vibration. They, however, had little effect on the seismic-proof design of the tank in the range of acceleration used in this study.

Dynamic Fluid Pressure in Vibration Experiment of Cylindrical Water Storage Tank

2004 ◽  
Vol 2004.5 (0) ◽  
pp. 199-200
Author(s):  
Akira MAEKAWA ◽  
Yasutaka SHIMIZU ◽  
Michiaki SUZUKI ◽  
Katsuhisa FUJITA
Keyword(s):  
Storage Tank ◽  
Fluid Pressure ◽  
Water Storage ◽  
Water Storage Tank ◽  
Vibration Experiment

Energy-saving analysis of air source heat pump integrated with a water storage tank for heating applications

2020 ◽  
Vol 180 ◽  
pp. 107029
Author(s):  
Pin Wu ◽  
Zhichao Wang ◽  
Xiaofeng Li ◽  
Zhaowei Xu ◽  
Yingxia Yang ◽  
...  
Keyword(s):  
Energy Saving ◽  
Heat Pump ◽  
Storage Tank ◽  
Water Storage ◽  
Water Storage Tank ◽  
Air Source Heat Pump

scholarly journals The effect of household storage tanks/vessels and user practices on the quality of water: a systematic review of literature

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Musa Manga ◽  
Timothy G. Ngobi ◽  
Lawrence Okeny ◽  
Pamela Acheng ◽  
Hidaya Namakula ◽  
...  
Keyword(s):  
Systematic Review ◽  
Water Quality ◽  
Storage Tank ◽  
Grey Literature ◽  
Water Storage ◽  
Storage Tanks ◽  
Water Storage Tank ◽  
Hygiene Practices ◽  
Quality Of Water ◽  
Vessel Material

Abstract Background Household water storage remains a necessity in many communities worldwide, especially in the developing countries. Water storage often using tanks/vessels is envisaged to be a source of water contamination, along with related user practices. Several studies have investigated this phenomenon, albeit in isolation. This study aimed at developing a systematic review, focusing on the impacts of water storage tank/vessel features and user practices on water quality. Methods Database searches for relevant peer-reviewed papers and grey literature were done. A systematic criterion was set for the selection of publications and after scrutinizing 1106 records, 24 were selected. These were further subjected to a quality appraisal, and data was extracted from them to complete the review. Results and discussion Microbiological and physicochemical parameters were the basis for measuring water quality in storage tanks or vessels. Water storage tank/vessel material and retention time had the highest effect on stored water quality along with age, colour, design, and location. Water storage tank/vessel cleaning and hygiene practices like tank/vessel covering were the user practices most investigated by researchers in the literature reviewed and they were seen to have an impact on stored water quality. Conclusions There is evidence in the literature that storage tanks/vessels, and user practices affect water quality. Little is known about the optimal tank/vessel cleaning frequency to ensure safe drinking water quality. More research is required to conclusively determine the best matrix of tank/vessel features and user practices to ensure good water quality.

scholarly journals Minimum Number of Experimental Data for the Thermal Characterization of a Hot Water Storage Tank

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4741
Author(s):  
María Gasque ◽  
Federico Ibáñez ◽  
Pablo González-Altozano
Keyword(s):  
Experimental Data ◽  
Water Temperature ◽  
Temperature Profile ◽  
Storage Tank ◽  
Water Storage ◽  
Hot Water ◽  
Experimental Temperature ◽  
Inlet Temperature ◽  
Water Storage Tank ◽  
Minimum Number

This paper demonstrates that it is possible to characterize the water temperature profile and its temporal trend in a hot water storage tank during the thermal charge process, using a minimum number of thermocouples (TC), with minor differences compared to experimental data. Four experimental tests (two types of inlet and two water flow rates) were conducted in a 950 L capacity tank. For each experimental test (with 12 TC), four models were developed using a decreasing number of TC (7, 4, 3 and 2, respectively). The results of the estimation of water temperature obtained with each of the four models were compared with those of a fifth model performed with 12 TC. All models were tested for constant inlet temperature. Very acceptable results were achieved (RMSE between 0.2065 °C and 0.8706 °C in models with 3 TC). The models were also useful to estimate the water temperature profile and the evolution of thermocline thickness even with only 3 TC (RMSE between 0.00247 °C and 0.00292 °C). A comparison with a CFD model was carried out to complete the study with very small differences between both approaches when applied to the estimation of the instantaneous temperature profile. The proposed methodology has proven to be very effective in estimating several of the temperature-based indices commonly employed to evaluate thermal stratification in water storage tanks, with only two or three experimental temperature data measurements. It can also be used as a complementary tool to other techniques such as the validation of numerical simulations or in cases where only a few experimental temperature values are available.

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