Physical model of fluid flows in spacecraft tank

The results of an experimental study of liquid fuel flows in the tanks of a spacecraft during its rotation are presented. The analysis of structure and character of flows development on time is carried out, variants of graphic dependences approximation are offered. Graphical diagrams are presented, according to which it is convenient to present a three-dimensional nonlinear picture of non-stationary axisymmetric flow in a spherical reservoir, as well as methods of influencing flows with the help of internal baffles. Estimation of the obtained experimental data probability testifies to the rather high quality of the measurement results and the constructed picture of the currents in the spherical tank with internal baffles.

Prioritization of Noise Control Solutions in an Oil Refinery Using the Noise Control Priority Index

Background: It is essential to decide on where to allocate available resources and identify priorities in noise control. Objectives: This study was performed to prioritize noise control solutions in various units of an oil refinery using the noise control priority index (NCPI). Methods: This cross-sectional study was conducted in an oil refinery in 2019. The standard of ISO 91612 was applied in the first stage to assess workplaces and determine the values of the noise pressure level (SPL). The activity of stations and the duration of workers’ presence in these stations were determined via interviews with the supervisors and senior personnel of each unit. The NCPI value in various units was determined using three variables, including the number of exposed people, exposure duration, and the weighting factor related to the sound pressure level (SPL). Finally, units were prioritized based on the final NCPI value. Results: Totally, 10 units were assessed based on the ISO9612 standard. The results revealed that 8.09% of the assessed stations were in the safe zone, 62.24% in the warning zone, and 29.66% in the hazard zone. The highest noise emission was related to the NTA unit (98 dB), and the lowest noise emission was observed in the spherical reservoir unit (84 dB). The NTA unit with 12 workers had the highest noise control priority index (1.25) among the units. Conclusions: The NCPI index makes it possible to appropriately prioritize noise control solutions in various industrial units and also implement technical and noise control plans in the oil and gas industries.

Numerical modeling of a double-walled spherical reservoir

Extensive and important class of multilayer shell structures is three-layer structures. In a three-layer structure, a rigid filler plays an important role, due to which the bearing layers are spaced that gives the layer stack high rigidity and durability with a relatively low weight. By combining the thicknesses of the bearing layers and the filler, the desired properties of a three-layer shell structure can be achieved. Compared with traditional single-walled, three-layer construction has increased rigidity and durability, which allows reducing the thickness and weight of the shells. In order to reduce the metal content of the spherical reservoir for storing liquefied gases, this work considers the design of a double-walled reservoir, in which the inter-wall space is filled with reinforced polyurethane. Numerical modeling made it possible to determine the parameters of the stress-strain state of the structure with an error of no more than 5 %. It has been established on the example of a reservoir with a volume of 4000 m3 that the spatial structure of the spherical reservoir wall can reduce the metal content up to 19 %. Field of application for the research results is the assessment of the stress-strain state of spherical reservoirs at their designing. Method for building the structure of a double-walled spherical reservoir in the SCAD software has been developed, which allows calculating the stress-strain state (SSS) by the finite element method. Numerical model of a double-walled spherical reservoir has been developed. It was found that to obtain calculation results with an error of P ≤ 5 % the size of the final element should not exceed 300×300×δ mm. Design of a double-walled spherical reservoir was investigated. Design parameters have been established to ensure the operational reliability of the structure with a decrease in metal content in comparison with a single-wall reservoir by 19 %.

Analysis of reservoir’s mass influence on the system free – surfaced liquid and spherical reservoir

Within the framework of combined motion the effect of ratio of masses of reservoir and liquid on the behavior of a free surface of liquid in the reservoir of spherical shape is studied. We suppose that liquid is ideal and it fills partially the reservoir. Mathematical modelling is done on the basis of the model, which takes into account combined character of nonlinear dynamics of liquid and the reservoir. Examples were done based on mathematical model of combined motion of liquid in spherical reservoir and free-surfaced liquid under harmonic force disturbance in horizontal direction. Two cases of the ratio of masses in the system are considered. First, the mass of the reservoir is 5 times less than the mass of the liquid; the mass of the reservoir is 5 times greater than the mass of the liquid. In order to identify specific features of the system behavior, the results were compared with the results for liquid behavior in cylindrical and conical reservoirs. It was ascertained that mass increasing has no tendency of converging to a steady mode of motion, which was confirmed experimentally. Distinctions of manifestation of nonlinear processes for the below-resonance, near-resonance and above-resonance modes are shown. We note manifestation of nonlinear effects such as modulation, the presence of high-frequency normal modes of oscillations, antiresonance and drift of the mean of oscillations.

ANALYSIS OF POWER INTERACTION OF A LIQUID AND A SPHERICAL RESERVOIR WHEN SYSTEM MOTION IS EXCITED BY A PERIODIC FORCE

Interaction of a reservoir with a free-surfaced liquid for vibration disturbance of the reservoir motion by a periodic force in a below-resonance, near-resonance and above-resonance ranges of frequencies is considered. Specific features of the effect of geometric shape of the reservoir on the development of dynamic processes are analyzed. For studying the system dynamics we consider variants of cylindrical and spherical reservoirs.

Thermal Homogenization in Spherical Reservoir by Electrohydrodynamic Conduction Phenomenon

Effect of electric conduction phenomenon on the mixing mechanism is studied numerically to thermally homogenize a dielectric liquid with an initial nonuniform temperature distribution. The fluid is stored in a spherical reservoir, and the electrodes are embedded on the reservoir surface such that the resultant local electric body forces mix the fluid. The electric field and electric body force distributions along with the resultant velocity field at the final steady-state condition are presented. The mixing mechanism is illustrated by the time evolution of temperature distribution inside the reservoir. The effects of primary dimensionless numbers on the mixing time are studied.

Thermal Homogenization in Spherical Reservoir by EHD Conduction Phenomenon

Electrohydrodynamic (EHD) conduction phenomenon involves the interaction of electric field and flow field in a dielectric fluid medium via the process of dissociation and recombination of free charges. This paper numerically studies the effect of electric conduction phenomenon on the mixing mechanism of two fluids with identical physical properties but separated due to the non-homogeneity of the temperature field. The fluid is designated to be restored in a spherical reservoir and it is not spontaneously mixed since the reservoir is predicted to be located in non-gravity environment. The electrodes are embedded on the reservoir surface such that the resultant electric body force causes the fluid with higher temperature mixes with the colder fluid and vice versa. The electric field and electric body force distribution and the resultant velocity field are presented. The results are illustrated in the form of time evolution of temperature distribution inside the reservoir. The effects of primary dimensionless numbers on the mixing time are studied.