[en] To study the variation regularities of the mass, evaporation, temperature, and pressure of LNG in the gas cylinder with time, LNG was used as the working medium, and three specifications of LNG gas cylinders (150L, 330L, and 450L) were selected for heat transfer calculation. For the liquefied medium in the LNG gas cylinders, a saturated homogeneous model was adopted. For the heat transfer calculation of the adiabatic layer of LNG gas cylinders, a multilayer insulation structure model of radiation and heat conduction was adopted. According to the thermodynamic relations in the saturated state, the relations between the temperature and the physical parameters of the liquefied medium were fitted. The calculation method and calculation model were verified by the experimental data of liquid nitrogen for three specifications of LNG cylinders (150L, 330L, and 450L). According to the calculation model, the variation regularities of LNG thermodynamic parameters with time were obtained at a normal temperature. In the initial period of evaporation, the increasing temperature rate of LNG, the evaporating rate of LNG, and the pressure-boost rate of LNG in the gas cylinder are slow, and then these rates increase. The final mass of boil-off gas (BOG) produced by the phase change finally reaches 0.68% of the total mass of the medium in the gas cylinder. (paper)

[en] Highlights: • Flow patterns in large cylinder arrays are experimentally studied. • Different flow patterns occur after the first row due to lower turbulence levels. • Bistable flows are identified in the array at a given transversal spacing ratio. • Trends are identified for the turbulence energy distribution along the rows. • The last row is at higher risk of vibration due to turbulent buffeting. - Abstract: Studies on flow-induced vibrations in large tube bundles are usually focused solely on frequency analysis, without considering the flow patterns which are responsible for the fluid forces. Furthermore, investigations which involve variations in the spacing ratios do not separate transversal and longitudinal proximity effects. The purpose of this article is to separately analyze the influence of the transversal (T/D) and longitudinal (L/D) spacing ratios of a confined in-line cylinder array with five rows on the flow characteristics and to identify flow patterns. The laser Doppler anemometry technique was employed to acquire the mean velocity and its fluctuations in the transversal and longitudinal directions between the cylinder rows. Strouhal numbers and regimes reported in the literature were identified in the experiments. The same regime did not always persist along all cylinder rows for a given spacing ratio, as a result of the combined longitudinal and transversal proximity effects and also of the generation of turbulence by the array. For the smallest T/D ratio, a quasi-steady behavior associated with the biased flow pattern was noted in the experimental set-up and flip-flopping was observed in one case. Additionally, the flow characteristics in these arrays diverged from tube bundle classifications described in the literature. The behavior of the fluid forces and susceptibility to vibrations in the array were predicted based on the turbulence intensity of the incident flow of the cylinders. The results reinforced the need to extend flow pattern investigations to arrays with more cylinder rows and to consider both transversal and longitudinal proximity effects, when studying flow-induced vibrations.

[en] In the 1980’s Manchester University carried out over 110 tests on cylinders with a composite wall (steel-concrete-steel) subjected to external pressure as already reported in the literature. This paper describes further tests on 9 cylinders with a composite wall and a dome end subjected to external pressure and reports the results and compares them with theory. The cylinders were 500 mm diameter and 1250 mm long and four of them had penetrations through the cylinder wall. These tests were carried out under contract for Tecnomare SpA of Italy and have not been previously reported because of confidentiality reasons. The agreement between test behaviour, failure load and the theory developed at Manchester University is good. The philosophy for the design of such vessels for seabed structures is discussed and a ‘depth margin’ method proposed as it is a more realistic way of applying safety. Examples of designs for different depths are given and compared with the predicted failure pressure. (Author)

[en] In this paper, we study a thick cylinder with uncertain external pressure. The traditional model was extended in fuzzy context. We use the governing equation which was rewritten as delta operator equation. The interpretations of external pressure are based on triangular, trapezoidal and Gaussian fuzzy numbers. By Adomian Decomposition Method gives an approximate solution. The maximal and minimal radial stresses are obtained, corresponding to the level cut. Finally, we get the methodology for simulating uncertain problems in fuzzy context and utility of each membership function. (paper)

[en] Classical problem of an infinite flow past an infinite porous cylinder perpendicular to its axis is considered for the micropolar liquid. It is demonstrated that for a porous body, classical Stokes paradox exists neither in non-polar nor in polar liquid, i.e. non-trivial solutions was found unlike in the case of impermeable infinite obstacle. The solution is presented in finite analytical form, which is ready for exploitation in experiments and engineering applications. The interrelation of liquid and porous medium characteristics and their influence on the flow velocity is studied.

[en] We present an alternative method to determine in a simpler and quicker way the reaction flux in circular loops and saddle-coil sets, as applied in rock magnetometers. The dipole may be in an arbitrary direction and on an arbitrary position with respect to the sensing coil set. After the evaluation of the reaction flux, several test experiments are presented which verify the calculations. Finally, the impact of the image effect on the signal uniformity in commercial rock magnetometers is discussed. (orig./BUD)

No abstract available

[en] Cylindrical structures such as pipes and shafts are widely used in various industrial facilities. Recently, researches on magnetostrictive transduction of torsional waves have been actively reported for the nondestructive evaluation of those cylindrical structures. However, the existing magnetostrictive patch transducer has somewhat inconvenient and time. Consuming process like patch bonding to a structure since it should employ a magnetostrictive patch having strong magnetostriction. To overcome these limitations of the existing transducer, in this work, we develop a novel modular magnetostrictive transducer to generate and measure torsional waves to inspect a cylindrical structure. The proposed transducer can be applied as viscous liquid coupling with shear couplant or dry coupling without coupling media instead of patch bonding to a structure. We describe a detailed structure of the modular transducer and conduct some experiments to verify its performance

No abstract available

[en] Highlights: • Effects of side ratio on energy harvesting from galloping of rectangles are studied. • The onset galloping velocity decreases with increasing the side ratio. • A side ratio of ∼1.0 is good for energy harvesting at high reduced flow velocities. • Side ratios within1.62–2.0 is beneficial for harvesting at low reduced velocities. Rectangular cylinders have been identified as ideal bluff bodies for galloping-based energy harvesting, while a systematic study of the effects of the side ratio (i.e., the ratio between the cylinder width and the cylinder height) remains unavailable. This study investigates the influences of the side ratio on the piezoelectric energy harvesting from the transverse galloping of a rectangular cylinder based on a representative electro-aero-mechanical model, in which the aerodynamic force is calculated by the quasi-steady theory. The existing experimental aerodynamic coefficients for rectangular cylinders with side ratios of 0.62–3.0 are utilized as inputs of the quasi-steady aerodynamic force model. The influences of the side ratio and load resistance on the onset velocity, displacement, and power output of the galloping-based energy harvester are investigated. The results show that the onset velocity of galloping is dependent on the load resistance while this dependency becomes less significant with increasing the natural frequency. The onset galloping velocity of the energy harvester decreases with increasing the side ratio, and the lowest onset velocity is achieved by a rectangular cylinder with a side ratio of around 2.50. The largest vibration amplitude is achieved by the cylinder with a side ratio of 1.62 or 2.0 at low flow velocities, while the largest vibration amplitude is always achieved by the square cylinder at high flow velocities. Therefore, the side ratio of a galloping-based energy harvester should be designed according to its working environment: the optimal side ratio is around 1.0 if the harvester is expected to work at relatively high reduced flow velocities, while the optimal side ratio is around 1.62–2.0 if the harvester is expected to be effective at relatively low reduced flow velocities. These conclusions can provide references for designing galloping-based energy harvesters with rectangular cylinders as bluff bodies.