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High liquid content is obtained in the T-junction side arm, which affects the operational performance of downstream equipment installed in offshore petroleum industries. Diameter ratio, velocity ratio, and side arm angle of T-junction play dynamic role to control phase redistribution. The effect of these parameters on liquid take-offs is unclear from literature, without any agreement among researchers. Literature only provides empirical correlations valid for one specific application for which the correlations were developed. There is a dire need of correlations with high accuracies to conclude the effect of a certain variable on liquid carryovers based on available data. Objectives of this study are to collect data from multiple research publications, develop easy to use correlations, and to study parameters response surfaces. Plot digitization and Design Expert software are utilized for data collection and statistical analysis, respectively. Results depicted that phase separation improves by reducing diameter ratio to 0.33 and upward inclined side arm. Furthermore, liquid carryovers escalate by increasing velocity ratio and decrease at higher velocity ratios. This research study is first attempt in last few decades which is based on collection of data from different experimentation facilities and eliminating confusions among researchers about effect of parameters on phase separation. [ABSTRACT FROM AUTHOR]

In recent years, there has been growing interest in olive genotypes (Olea europaea L.) suitable for super-high-density (SHD > 1200 trees/hectare) orchards. To date, only a few cultivars are considered fitting for such cultivation system. In this study, the first results on the architectural characteristics of the canopy of ten new olive genotypes are presented. Their suitability for SHD orchards was evaluated and compared with the cultivar 'Arbequina', which is considered suitable for SHD olive orchards and, for this reason, was used as the control. Several canopy measurements were taken, and some architectural parameters, such as branching frequency, branching density, and branch diameter/stem diameter ratio were calculated. The branching frequency value was greater than 0.20 in 'Arbequina' and in only four of the genotypes. The branching density in five genotypes was similar to 'Arbequina'. 'Arbequina' had the lowest value for the branch diameter/stem diameter ratio, and only three genotypes had similar values. These initial results showed that only one genotype has all canopy architectural characteristics comparable to those of the cv. 'Arbequina'. Further studies are needed to evaluate the production traits of these new genotypes and complete their characterization. [ABSTRACT FROM AUTHOR]

In recent years, there has been growing interest in olive genotypes (Olea europaea L.) suitable for super-high-density (SHD > 1200 trees/hectare) orchards. To date, only a few cultivars are considered fitting for such cultivation system. In this study, the first results on the architectural characteristics of the canopy of ten new olive genotypes are presented. Their suitability for SHD orchards was evaluated and compared with the cultivar ‘Arbequina’, which is considered suitable for SHD olive orchards and, for this reason, was used as the control. Several canopy measurements were taken, and some architectural parameters, such as branching frequency, branching density, and branch diameter/stem diameter ratio were calculated. The branching frequency value was greater than 0.20 in ‘Arbequina’ and in only four of the genotypes. The branching density in five genotypes was similar to ‘Arbequina’. ‘Arbequina’ had the lowest value for the branch diameter/stem diameter ratio, and only three genotypes had similar values. These initial results showed that only one genotype has all canopy architectural characteristics comparable to those of the cv. ‘Arbequina’. Further studies are needed to evaluate the production traits of these new genotypes and complete their characterization.

Two-dimensional numerical simulations for flow and heat transfer around two heated and unheated tandem cylinders are done for the Reynolds number Re = 150, and the temperature ratio Ts*=1−2.3. Ts* is defined as a ratio of cylinder surface temperature Ts and free stream flow temperature T∞. The spacing ratio L/Dd is varied in the range of 2to8, and diameter ratios Du/Dd in between 0.5to2, where L is the center-to-center distance between the upstream cylinder having diameter Du and the downstream cylinder having diameter Dd. Four different heating scenarios were considered: (1) both unheated cylinders (reference), (2) heated upstream cylinder, (3) heated downstream cylinder, and (4) both heated cylinders. The mean drag coefficient CD‾, fluctuations in the amplitude of the drag coefficient CD, root mean square (RMS) of lift coefficient CL′, mean surface heat transfer coefficient h‾ and Strouhal number St were obtained as a function of L/Dd and Du/Dd for both upstream and downstream cylinders. CD‾ on the downstream cylinder reduces to a value lower than that of a single cylinder in all cases due to the presence of the upstream cylinder. In addition, CD‾ on both cylinders generally increases with the increase in L/Dd for a constant Du/Dd. A major fall of 89.7% in CD‾ is seen at L/Dd = 4 and Du/Dd = 1 for the downstream cylinder when only the downstream cylinder is heated compared with both unheated cylinder scenarios. Similarly, a fall of 117.5% is seen in CD‾ on the downstream cylinder is observed for both the cylinders heated scenario at L/Dd = 8 and Du/Dd = 2. For upstream heated cylinder cases, around 96.4% rise in h‾ is observed for the Du/Dd from 2 to 0.5 for all L/Dd, while for the downstream heated cylinder scenario, for L/Dd = 2 and 4, the rise in h‾ is 46.2% and 71.5%, respectively, when reducing the Du/Dd from 2 to 0.5.

AbstractThe study of contact mechanics is rapidly expanding in scope and importance. However, most studies of spherical do not spend significant time comprehensively analysing PEEQ, especially in the effect of friction coefficient and diameter ratio. This study aims to introduce comprehensive research examining diameter ratio and friction coefficient influencing equivalent plastic strain (PEEQ) during contact between two brass solids. In this study, the finite element method analysed an elastic-perfectly plastic brass material. The finite element model was two hemispheres with diameter ratios ranging from 1 to 5. In addition, the diameter in the upper hemisphere is 17.5 mm in all variations, while the bottom hemisphere follows the diameter ratio. The current study confirmed that the finite element results agreed well with the previous results’ analytical contact models. The findings also revealed that differences in ratio diameter and friction coefficient were significant to PEEQ. Therefore an increase in the coefficient of friction causes an expansion of the maximum PEEQ area for a diameter ratio of 1 and a reduction in the PEEQ maximum area for diameter ratios of 2 to 5. Expansion and contraction on the PEEQ area indicated that the contact radius widens and contracts as the coefficient of friction and diameter ratio change. Further research is required to investigate the effect of other parameters in PEEQ analysis, such as material properties and multiple cycle loading conditions. Furthermore, the practical implications of these findings may contribute to our understanding of engineering design and failure analysis.

Ultra-high-performance concrete (UHPC)-filled duct connection is an innovative solution for joining assembled structures, in which the anchorage performance of the rebar and UHPC filled in bellows plays a critical role in determining the overall connection effectiveness. To establish a reliable anchorage length and a bond–slip relationship between rebar and UHPC within a bellow, a total of 16 specimens were conducted, and pullout tests were carried out. Two parameters were considered, including the diameter ratio (D/d), representing the proportion of the diameter of the bellow D to the diameter of the steel bar d, and anchorage length (L). By analyzing the failure modes, load versus deflection curves, and steel strain data, the influences of the diameter ratio and anchorage length on the anchorage performance were discussed. The test results showed that the failure mode changed from rebar pullout to rebar breakage as the anchorage length increased from 3 d to over 10 d. The reliable anchorage length of the rebar was recommended to be at least 10 d with a diameter ratio (D/d) of 2.4. Moreover, a fitting bond–slip model was proposed based on the experimental bond–slip curves between the rebar and UHPC interface within the bellows with high precision. These findings constitute a crucial basis for the comprehensive stress analysis of assembled structures connected using UHPC grouted in bellows. [ABSTRACT FROM AUTHOR]

To control greenhouse gas emissions and improve the sustainability of renewable energy technologies, thermal energy storage systems are receiving significant attention in recent years. Extensive research has been conducted on shell-and-tube Latent Heat Thermal Energy Storage (LHTES) systems to match energy supply and demand. The selection of the tube and shell diameter in the heat exchanger is a crucial aspect in the design of LHTES systems. This research intends to deliver the most suitable shell-to-tube diameter ratio for the complete operation of horizontal thermal energy storage. Different shell-to-tube diameter ratios were studied using two schemes: (i) varying the shell diameter on a fixed-sized inner tube, and (ii) varying the inner tube diameter within a fixed shell diameter. The outer shell was constructed of acrylic, while the inner tube was made from copper, and paraffin RT50 was used as the phase change material. Numerical simulations were performed using the enthalpy-porosity method and verified with data from the literature. Performance indicators, such as average liquid fraction, temperature, average storage/retrieval rate, Fourier number and storage/retrieval density were utilized to evaluate the system's performance. Results indicated that the thermodynamic characteristics were similar in both schemes. The maximum energy density was found to be around 268 kJ/kg and remained constant until a diameter ratio of 5 and 4 for the charging and discharging processes, respectively, before decreasing. During charging, the Fourier number decreased initially and then stabilized at 0.4 after the diameter ratio of 5, while it stabilized at 1.2 during discharging. The best diameter ratio was found between 4 and 5 for the charging process, and between 3 and 4 for the discharging process. Ultimately, the most suitable diameter ratio was recommended as 4 for the complete cycle. • Effect of shell-to-tube diameter ratio in a horizontal LHTES has been investigated. • Energy storage density remains constant up to a specific diameter ratio. • Fourier number plays a critical role in identifying the best diameter ratio. • Most favourable ratio lies between 4 and 5 for charging and 3 to 4 for discharging. • Overall, the most suitable ratio is recommended as 4 for the complete operation. [ABSTRACT FROM AUTHOR]

The study of contact mechanics is rapidly expanding in scope and importance. However, most studies of spherical do not spend significant time comprehensively analysing PEEQ, especially in the effect of friction coefficient and diameter ratio. This study aims to introduce comprehensive research examining diameter ratio and friction coefficient influencing equivalent plastic strain (PEEQ) during contact between two brass solids. In this study, the finite element method analysed an elastic-perfectly plastic brass material. The finite element model was two hemispheres with diameter ratios ranging from 1 to 5. In addition, the diameter in the upper hemisphere is 17.5 mm in all variations, while the bottom hemisphere follows the diameter ratio. The current study confirmed that the finite element results agreed well with the previous results' analytical contact models. The findings also revealed that differences in ratio diameter and friction coefficient were significant to PEEQ. Therefore an increase in the coefficient of friction causes an expansion of the maximum PEEQ area for a diameter ratio of 1 and a reduction in the PEEQ maximum area for diameter ratios of 2 to 5. Expansion and contraction on the PEEQ area indicated that the contact radius widens and contracts as the coefficient of friction and diameter ratio change. Further research is required to investigate the effect of other parameters in PEEQ analysis, such as material properties and multiple cycle loading conditions. Furthermore, the practical implications of these findings may contribute to our understanding of engineering design and failure analysis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University of Engineering Science / Shanghai Gongcheng Jishu Daxue Xuebao is the property of Journal of Shanghai University of Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study examines the flow and thermal characteristics of a tube containing perforated conical inserts by varying the Reynolds number in the range of 4000–20000. The perforated conical insert having (d/D) ratio of 0.3, (p/D) ratio of 2, (x/L) ratio of 0.25, and N = 6 showed the minimum entropy generation. Second law analysis showed that the solid inserts of a lower pitch to diameter ratio are suitable to transfer high energy transfer at lower Reynold's number, whereas the perforated conical inserts are found to be effective at higher Reynolds numbers. Empirical correlations are developed for solid and perforated conical inserts. [ABSTRACT FROM AUTHOR]

In recent years, three kinds of auxetic yarns have mainly been developed, namely helical auxetic yarns based on the ring spinning system and the hollow spindle system and braided auxetic yarns based on the braiding system. However, these auxetic yarns have some drawbacks, such as an unstable structure or no obvious auxetic effect. In this paper, auxetic yarns were successfully braided by wrap filaments and a core filament based on a braiding system, which overcame the slippage problem in the traditional helical yarn structure. Yarns were spun by different structural parameters of the core filament, the wrap filaments and braiding filament, including the diameter ratio, braiding speed and different numbers of wrap filaments. The results showed that all parameters have an impact on the Poisson's ratio of auxetic yarns and, in addition, the braided auxetic yarns can cause the yarns to be in the pre-stretching state; once the stretching effect occurs, the Poisson's ratio will directly change from a negative value. Since the new auxetic yarns were produced using a high-speed braiding machine and filaments, this would pave the way for their mass production. This provides a certain research basis for mass production of the stable auxetic yarn structure, and based on the realization of the pre-stretching state, it also provides more possibilities for future research. [ABSTRACT FROM AUTHOR]

An improved model to calculate the length of the mixing chamber of the ejector was proposed on the basis of the Fano flow model, and a method to optimize the structures of the mixing chamber and diffuser of the ejector was put forward. The accuracy of the model was verified by comparing the theoretical results calculated using the model to experimental data reported in literature. Variations in the length of the mixing chamber Lm and length of the diffuser Ld with respect to variations in the outlet temperature of the ejector Tc, outlet pressure of the ejector pc, and the expansion ratio of the pressure of the primary flow to that of the secondary flow pg/pe were investigated. Moreover, variations inLm and Ld with respect to variations in the ratio of the diameter of the throat of themotivenozzle to thediameterof themixing chamber dg0/dc3 and ratioof the outlet diameter of thediffuser to the diameter of themixing chamber dc/dc3 were investigated. The distribution of flowfields in the ejector was simulated. Increasing Lm and dc3 reduced Tc and pc. Moreover, reducing pg/pe or dg0/dc3 reduced Tc and pc. The length of the mixed section Lm2, which was determined on the basis of the Fano flow model, increased as pg increased and decreased as dc3 increased. The mixing length Lm1, which was considered the primary flow expansion, showed the opposite trend with that of Lm2. Moreover, Ld increased as pg/pe and dc/dc3 increased. When the value of dc was 1.8 to 2.0 times as high as that of dc3, the semi-cone angle of the diffuser ranged between 6° and 12°. At a constant dc/dc3, decreasing Tc and pc increased Ld. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC)-filled duct connection is an innovative solution for joining assembled structures, in which the anchorage performance of the rebar and UHPC filled in bellows plays a critical role in determining the overall connection effectiveness. To establish a reliable anchorage length and a bond–slip relationship between rebar and UHPC within a bellow, a total of 16 specimens were conducted, and pullout tests were carried out. Two parameters were considered, including the diameter ratio (D/d), representing the proportion of the diameter of the bellow D to the diameter of the steel bar d, and anchorage length (L). By analyzing the failure modes, load versus deflection curves, and steel strain data, the influences of the diameter ratio and anchorage length on the anchorage performance were discussed. The test results showed that the failure mode changed from rebar pullout to rebar breakage as the anchorage length increased from 3 d to over 10 d. The reliable anchorage length of the rebar was recommended to be at least 10 d with a diameter ratio (D/d) of 2.4. Moreover, a fitting bond–slip model was proposed based on the experimental bond–slip curves between the rebar and UHPC interface within the bellows with high precision. These findings constitute a crucial basis for the comprehensive stress analysis of assembled structures connected using UHPC grouted in bellows.

In this paper, the challenge is to increasing of the heat exchanger performance by placing different size balls inside the tubes. the development of previous studies to enhance relatively bad case of heat transfer where the inserting (a large ball and then a small ball) to collide the water molecules in the ball and generate turbulent flow (Reynolds number range from 50,000 to 350,000) and thus increase the thermal performance due to collision of particles with the inner casing of the tube and reduce the stagnation near the wall. The usefulness of small ball, after the big ball, is Reduce of gets wake flow. A simulation was made when changing the diameter ratio of big to small ball (Dr = 3, 4, 5). Also, the distance between the big ball and the small ball was changed (X = 2, 3, 5) mm. It was concluded that the best ball diameter ratio and best Distance is (Dr= D_b/D_sb = 5), (X = 3 mm), respectively. The pressure drop acts as a side effect of enhancement. Therefore, the method of equal pumping was adopted. The average thermal performance factor (TPF=1.178) of tube with insert the balls enhanced by 17.8% at (x=3mm) and (Dr=5) when compared with smooth tube.

T-junction is broadly utilized for phase separation, as it has a notable function as a conduit to distribute fluid, due to its simple design, low maintenance cost and adaptability to offshore industries. The geometrical parameters that influence phase separation make the phase re-distribution unpredictable. Even though the diameter ratio of the T-junction has a prominent effect on phase separation, it was not thoroughly and comprehensively reviewed specifically. This review article intends to fill in that gap, focusing solely on the effect of the diameter ratio on phase separation, specifically for two-phase flow in branching T-junction. Initially, the inversely proportional relation between diameter ratio and phase separation is discussed, reported first in the 1970s. Besides, a critical analysis in 1998, is reported which challenged the inverse proportionality. Unfortunately, their disagreement was not addressed for more than a decade. Lastly, two different criteria to determine the separation efficiency, state-of-the-art T-junction design and side arm modifications are summed up with conclusions. The primary contribution of this research is that it takes into account the agreement and disagreements among the researchers for inverse proportionality between phase separation and diameter ratio, including some critical findings that were not reported in the past in review articles. Some recommendations for future research in this domain are also reported.

Chamfered circular ring (CCR) innovated from conventional circular ring by introducing chamfered surface on its periphery at 30o attack angle is numerically investigated to study its effect on fluid flow characteristics, heat transfer enhancement, and friction factor in a heat exchanger pipe. In order to study flow blockage effect on overall performance of device, three diameter ratios (DR = Di/Do = 0.6, 0.7 and 0.8) with three spacing ratios (SR = s/D = 1, 2 and 3) are used. Turbulent model k – ε, RNG with enhanced wall treatment is used to solve governing equations. Results showed that CCR chamfered surface produced nozzle jet effect on pipe wall surface through clearance of 1 mm, which further induced turbulent and recirculating flow effect near pipe wall area. This resulted into higher heat transfer rate. All the diameter ratios with SR = 1 showed thermal performance factor value more than unity at most of the lower Reynolds number. The range of TPF shown by DR = 0.6, 0.7 and 0.8 with SR =1 is 1.21–0.93, 1.23–0.97, and 1.19–0.99, respectively. Compromised results of TPF are shown by DR = 0.7 and DR = 0.8 at SR = 1. Chamfered circular ring has shown better results over circular ring, perforated conical ring, short length twisted tape, twin co-twisted tape, wire rod bundles, and perforated twisted tape. Numerical results showed better agreement with predicted results within the range of 10%. Highest TPF of 1.23 is shown by DR = 0.7 and SR = 1 at Re 6000. Graphical Abstract [ABSTRACT FROM AUTHOR]

The transient flow behind a bluff body is a common phenomenon in engineering applications. However, most of the research attention is fully developed flow, rather than the initial stages of flow formation. In this work, the transient flow in the initial stage behind a translationally and rotationally started cylinder with multiple control cylinders is investigated by the dynamic mesh method. The solutions in this paper agree well with the experimental data and numerical solutions reported in the open literature. The results show that the shedding of the vortex from the transient flow in the initial stage slows down with the increase of the number of control cylinders. The magnitude of the hydrodynamic coefficient of the main cylinder decreases with the increase of diameter ratios, but the fluctuations and instability of the transient flow are generated at the same time. [ABSTRACT FROM AUTHOR]

The ducted tidal turbine models have been developed to utilize the conversion of the kinetic energy on ocean currents. The research in refining the turbine characteristics has been carried out by modifying the turbine’s shape and size. This study investigated flow characteristics in the meridional section of five ducted turbines models for seawater flow with velocity U0 = 1.5 m/s. The ducted turbine design and construction have five different impeller house diameters and fixed inlet and outlet diameters. The potential energy flow theory and experimental data are used to analyze the flow characteristics of the model. The results show that flow velocity in the x-direction at the inlet and outlet cross-section is getting smaller, reducing the impeller house cross section. Each impeller house size reduction increases the flow speed in the impeller house cross-section and also pressure on all other cross-sections tested. In the inlet area, the increased pressure indicates a decrease in speed flow and discharge coefficient value. The discharge coefficient value decreases from CQ = 0.9 at the diameter ratio of dr = 1 to CQ = 0.56 at the diameter ratio of dr = 0.375. The maximum value of power coefficient was determined at dr = 0,61÷0.73 or dr = 0.69 which is equivalent to average internal flow velocity Vr =2.0÷2.6 m/s and the static pressure ps = 97.1÷ 94.4 kPa. At the ratio value of D0/D2 = 0.83, the optimal diameter ratio dropt=0,61÷0.73 is in line with the duct model of case 3 and case 4, but it may be determined solely as for case 4.

In this study, the dynamic characteristics of water droplets impinging on a heated cylinder were investigated using a high-speed camera regarding the diameter ratios between droplet and cylinder. Water droplets generated by a needle in the range of 2.5 mm to 5.0 mm in diameter were impinged onto a cartridge heater with surface temperature of 25 °C and 300 °C. The diameter of the cartridge heater was 6.0 mm. The recording rate of the high-speed camera was set to 10,000 Hz, and the Weber number was controlled from 17.4 to 217 by adjusting the free-fall height of the water droplets. As a result, the dynamic characteristics of water droplets impinging on cylinder were different depending on the diameter ratio and Weber number. In the high-temperature region, the water droplets were detached from the cylinder after the impingement by Leidenfrost effect. Under conditions of low Weber number and low diameter ratio, the water droplets were rebounded in the opposite direction of the impingement, maintaining its shape. However, as the Weber number increases, the water droplets impinging on cylinder were broken-up and detached by the Leidenfrost effect regardless of the diameter ratio. This study is expected to be utilized to determine the dynamic characteristics of droplet, and be applied such as phenomenon analysis of the heat transfer and cooling. [ABSTRACT FROM AUTHOR]

Owing to its high heat storage capacity and fast heat transfer rate, packed bed latent heat storage (LHS) is considered as a promising method to store thermal energy. In a packed bed, the wall effect can impact the packing arrangement of phase change material (PCM) capsules, inducing radial porosity oscillation. In this study, an actual-arrangement-based three-dimensional packed bed LHS model was built to consider the radial porosity oscillation. Its fluid flow and heat transfer were analyzed. With different cylindrical sub-surfaces intercepted along the radial direction in the packed bed, the corresponding relationships between the arrangement of capsules and porosity oscillation were identified. The oscillating distribution of radial porosity led to a non-uniform distribution of heat transfer fluid (HTF) velocity. As a result, radial temperature distributions and liquid fraction distributions of PCMs were further affected. The effects of different dimensionless parameters (e.g., tube-to-capsule diameter ratio, Reynolds number, and Stefan number) on the radial characteristics of HTF and PCMs were discussed. The results showed that different diameter ratios correspond to different radial porosity distributions. Further, with an increase in diameter ratio, HTF velocity varies significantly in the near wall region while the non-uniformity of HTF velocity in the center region will decrease. The Reynolds and Stefan numbers slightly impact the relative velocity distribution of the HTF—while higher Reynolds numbers can lead to a proportional improvement of velocity, an increase in Stefan number can promote heat storage of the packed bed LHS system.

In this paper, the challenge is to increasing of the heat exchanger performance by placing different size balls inside the tubes. the development of previous studies to enhance relatively bad case of heat transfer where the inserting (a large ball and then a small ball) to collide the water molecules in the ball and generate turbulent flow (Reynolds number range from 50,000 to 350,000) and thus increase the thermal performance due to collision of particles with the inner casing of the tube and reduce the stagnation near the wall. The usefulness of small ball, after the big ball, is Reduce of gets wake flow. A simulation was made when changing the diameter ratio of big to small ball (Dr = 3, 4, 5). Also, the distance between the big ball and the small ball was changed (X = 2, 3, 5) mm. It was concluded that the best ball diameter ratio and best Distance is (Dr= Db/Dsb = 5), (X = 3 mm), respectively. The pressure drop acts as a side effect of enhancement. Therefore, the method of equal pumping was adopted. The average thermal performance factor (TPF=1.178) of tube with insert the balls enhanced by 17.8% at (x=3mm) and (Dr=5) when compared with smooth tube. [ABSTRACT FROM AUTHOR]

Fixed bed reactor as a commonly used catalytic device and adsorption equipment in the chemical industry has attracted widespread attention. This paper presents a simple and feasible method which combines CFD with DEM to simulate the fixed bed reactor with the diameter ratio ranges in 2–8. The variation of the void ratio with different diameter ratios obtained from the model used in this paper was in comparison with the theoretical results derived by de Klerk and Dixon. The maximum error between the simulated results and the theoretical results was less than 10%, indicating that the model used in this study had a high degree of confidence. On this basis, the effects of the diameter ratio on the distribution of velocity and pressure were investigated. The distribution of velocity and pressure at different diameter ratios illustrated that when the diameter ratio was 5, the velocity distribution was uniform, and the pressure drop was relatively insignificant, which was beneficial to the reaction process. The model used in this paper could provide a new and concise method for the design and verification of fixed bed reactor. [ABSTRACT FROM AUTHOR]

The simple geometry configuration of T-junctions and their capability to act as partial phase separators, especially on offshore platforms, made them common pipeline system components in power and process industries. Moreover, in the pursuit of achieving better phase separation by controlling the maldistribution occurred in the component phases of a mixture at the junction, industries often utilise reduced T-junctions. Nevertheless, most of the published data in which industries was based on to adopt the previous configuration was relating on fully horizontal T-junctions with large main pipe diameters although T-junctions are rarely placed in a horizontal position in such industries, whilst the usage of small main pipe diameters could also lead to scaling down their size. In this regard, the present paper aimed to extend the available data by performing numerical analysis and studying both regular and reduced T-junctions with a small main pipe diameter, and upward inclination angles. It was observed that reduced Tjunctions performed worse in terms of phase separation compared to regular T-junctions for all inlet conditions applied and irrespective of the side arm inclination, whereas in case of regular T-junctions a superior separation performance was ensured for the inclined side arm at 30°.

In the present work, conical frustums (d/D = 0.3) are used as turbulators to form an insert of a heat exchanger tube. Both the perforated and imperforated conical inserts in a diverging arrangement (DR arrangement) are experimentally studied. The effects of the parameters like pitch ratio (p/D), the number of perforated holes (N), and relative location of perforations (x/L) on thermal and fluid characteristics are investigated. The results indicate that the inserts are effective in mixing the fluid at a lower temperature in the core region with the fluid at a higher temperature near the wall. Perforation and its effect on thermo-hydraulic performance are critically examined in the study. Perforations near the small-end diameter of the conical insert are found to be effective in terms of reduction in frictional loss and also increment of heat transfer near the wall region. The maximum thermo-hydraulic performance (η) is found to be 1.38 for the perforated conical insert in the diverging arrangement (PDR) having d/D = 0.3, p/D = 2, x/L = 0.5, N = 4 at the Reynolds number of 6258. [ABSTRACT FROM AUTHOR]

The hydraulic capsule pipeline (HCP) is regarded as the third-generation pipeline, first and second generation being fluid and slurry pipelines, respectively. For increasing the performance of these pipelines, capsule numbers in the pipeline must be increased, thereby increasing solid throughput. In the present study, computational fluid dynamics (CFD) modeling of a three-dimensional (3D) concentric capsule train was carried out. The focus of this work was to study the effects of intercapsule spacing (S), diameter ratio (k), and aspect ratio (a) on the performance of the pipeline in amount of energy consumption. Results show that for k=0.8 , a=1.25 , and S=0.75 times of capsule length, the capsule train requires minimum power to move ahead. A detailed optimal cost analysis was also carried out, which revealed that total cost of the pipeline is first reduced then increased with the enlargement in pipeline diameter. Hence, optimizing the diameter of a hydraulic pipeline transporting capsule was the subject of this study. [ABSTRACT FROM AUTHOR]

Heave plates are structural components used for reducing the vibrations caused by environmental forces on marine and offshore structures by changing the hydrodynamic properties. The fact that the added mass increase via heave plates does not always lead to the structural response reduction underscores the role of damping in maintaining the vibration amplitude within allowable limits. In the present experimental study, a novel combined rigid-elastic design is used to improve the damping through the velocity increase in the elastic part and added mass creation in the central rigid part. The desired percentage of total added mass and damping can be adjusted by changing the rigid-to-elastic parts diameter ratio, which is the main scope of this experimental research. Frequency of vibration, which affects the elastic edge excited mode shapes, also affects the forming of the vortex shedding. Experimental tests show that the frequency increase generally causes high damping performance provided that the excited mode shapes are axisymmetric, which strongly depends on equivalent stiffness and mass. [ABSTRACT FROM AUTHOR]

Circular ring inserts are found to enhance the heat transfer rates in the tube flow, while perforations in the ring inserts mitigate the frictional losses. In this study, the geometry of perforated ring is modified by creating lanced holes with a deflector. The experimental data for lanced ring are collected by varying the pitch ratio from 3.33–6.66 and diameter ratio from 0.5–0.6 in the Reynolds number range of 10000–37754. The enhancements in the Nusselt number and friction factor are found to vary in the range of 1.69–4.1 and 16–72, respectively. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vortex induced vibration (VIV) is the major cause of several catastrophic disasters due to fatigue failures induced by drag and lift forces in aerodynamic systems. This study investigates the control of VIV phenomenon through passive bubble tab(s) having a small diameter (d) relative to the main circular cylinder (D) in a two-dimensional (2-D) flow domain. Using ANSYS Fluent computational software, flow analysis was conducted at a Reynolds number (Re) of 80 for various bubble tab configurations at different spacing ratios (x/D) and diameter ratios (d/D). The drag coefficient, the velocity and pressure contours, along with the flow streamlines in each case were studied. The results indicated the optimized tab(s) positions for different spacing ratios, diameter ratios, and configurations. The study effectively established that passive bubble tabs can potentially control VIV associated with flows around a circular cylinder. [ABSTRACT FROM AUTHOR]

Introduction: An increase in Pulmonary Artery (PA) pressure is associated with an increase in its diameter. Hence, it is necessary to know the normal range of Main Pulmonary Artery Diameter (MPAD). An attempt has been made to know the same among the Indian population. Aim: To determine the normal range of reference values for diameter of Main Pulmonary Artery (MPA) and its relation with Ascending Aorta (AA) in Indian population. Materials and Methods: A prospective cross-sectional study was conducted between October 2018 and September 2019 ((380 males, 120 females) between the age of 30-65 years). Data from the contrast CT scans of thorax of 500 subjects such as those patients with cough under evaluation, suspected lung nodule, chest wall lesions, primary or secondaries in the lung, etc., who visited the Department of Radio-diagnosis, in the Medical College of South India were analysed. Further, healthy population was also defined as those who were free from chronic cardiopulmonary illness in particular with regard to present study, which would affect the diameter of great vessels including that of PA and aorta. MPA and ascending aortic diameters were measured at the level of pulmonary artery bifurcation, viewed at fixed mediastinal window settings. Statistical Package for Social Sciences (SPSS) version 20, inferential statistics like Unpaired-t test were used to test the significant difference for variables between the two groups (males and females). The level of significance was set at 5%. Results: The MPADs of whole population ranged between 15.6- 31.6 mm, with mean diameter of 23.08±2.81 mm. Correlation between age and MPAD was statistically significant (p-value

Summary: The ring fire usually originates from the combustion of the annular‐distributed fuel, and it may occur in the low‐temperature environments such as the Arctic area and plateau area, which is kind of different from the conventional environment. In this paper, the annular pools with various shape characteristics were designed. The outside diameter ranged from 14.9 to 30.0 cm, the inside diameter increased from 0 to 24.5 cm, and the diameter ratio was from 0 to 0.858. A series of n‐heptane ring fire experiments were carried out. The results showed that for the annular pools with the same outside diameter, the mass loss rate (MLR) per unit area presents a piecewise trend with the diameter ratio. When the diameter ratio increases from 0 to 0.7, the MLR per unit area increases linearly because of the domination of air entrainment effect. When the diameter ratio is larger than 0.7, the MLR per unit area is independent of the annular shape due to the strong heat dissipation effect. Finally, a parameter named the outside circumference per unit area is put forward to characterize the annular pool. A corrected pressure modeling is established to normalize the ring fire with various shape characteristics. [ABSTRACT FROM AUTHOR]

Flow fields in the distal end-to-side anastomosis of coronary artery bypass graft are associated with intimal hyperplasia and bypass failure. This work aims to demonstrate the effect of anastomotic angle and diameter ratio on flow field of coronary artery bypass graft. The flow fields inside polydimethylsiloxane models of coronary artery bypass graft with various anastomotic angles (α = 30°, 45°, 60° and 75°) and different diameter ratios (Φ = 0.78 and 1.11) are investigated using particle image velocimetry and computational fluid dynamics method under pulsatile flow condition. The results show that the anastomotic angle is positively correlated with the number and area of the recirculation zone, and the flow field disturbance at the anastomosis will develop in the same direction. Compared with that of Φ = 0.78, when Φ = 1.11, the flow fields at the anastomosis are relatively smoother with less turbulence. [ABSTRACT FROM AUTHOR]

The microstructures with spherical end have been widely applied in micromachining and measurement. In this paper, a microelectrode with spherical end was fabricated combining electrochemical etching with spark discharge machining. Firstly, the formation mechanism of micro spherical electrode was simulated by molecular dynamics LAMMPS, and the energy model of the spherical end was established to guide machining micro spherical electrode. Secondly, on the basis of cylindrical microelectrode, the electrode tip was melted by spark discharge. Simultaneously, the molten electrode formed a spherical end due to surface tension in deionized water. Finally, sets of experiments were carried out to discuss the influence of polarity, applied voltage, and pulse width on the diameter ratio of spherical end to electrode tip. By using optimal machining parameters, the micro spherical electrode with a diameter of 21.25 μm and a coaxial error of 0.9 μm can be obtained, and the diameter ratio is almost 2. [ABSTRACT FROM AUTHOR]

Experimental and modeling studies have been performed to determine mixing characteristics of binary mixtures in a spout-fluid bed. Spherical glass beads of diameters (3.075, 1.7, 1.2, and 0.75 mm) and air as fluidizing medium have been used in the study. Effect of various system parameters, namely, initial static bed height, gas velocity, diameter ratio, mixture composition, and sampling time on mixing of binary particles has been experimentally investigated. A dimensionless correlation has been developed for mixing index. Mixing behavior has been modeled using artificial neural networks (ANNs). Training of ANN was performed using the Levenberg–Marquardt (LM) backpropagation algorithm to predict the mixing index. The predictions of the ANN were found to be in good agreement with the experimental results and predictions from developed correlations. [ABSTRACT FROM AUTHOR]

This paper presents the results of laboratory experiments and numerical simulations to investigate the effect of different piggyback pipeline configuration on the morphology of local seabed scour subject to steady currents. Piggyback pipeline configuration investigated includes the commonly used piggyback pipeline, namely a small pipe attached on the top of large pipe and new form of piggyback pipeline proposed in this study in which a small pipe is attached to the large pipe on the upstream and downstream side, respectively. Pressure gradient, drag coefficient, lift coefficient and scour extent around pipelines are measured and analyzed for a range of pipelines and current conditions. Results show that the vortex strength downstream of the commonly used piggyback pipeline is larger than that for a single as well as the new piggyback pipeline under the same condition. This new type piggyback pipeline can effectively reduce the depth and width of the scour hole. In particular, when the ratio of the small pipe diameter over the large pipe diameter is greater than 0.3, little scour under this new type piggyback pipeline occurs for the test conditions. The bed topography downstream of the pipe has also been altered to favor the backfill. • A new type of piggyback pipeline structure is proposed. • New type of piggyback pipeline reduces the depth and width of scour hole • Little scour occurs when pipe diameter ratio over a certain value. [ABSTRACT FROM AUTHOR]

Highlights • Energy and RANS equations with SST k-ω model are solved in transient mode. • The CBHE with a lower diameter ratio has better thermal performance and cooling. • Minimum pumping power is achieved at a diameter ratio of 0.65. • With decreasing diameter ratio, drilling cost is reduced. Abstract In this paper, the thermal and hydrodynamic performance of the coaxial borehole heat exchanger (CBHE) with different diameters ratio, during heat injection into the ground are investigated. For this purpose, the energy and Reynolds Averaged Navier-Stokes (RANS) equations with SST k-ω turbulence model are numerically solved to simulate transient fluid flow and heat transfer. Numerical simulation results are validated with results of available experimental data. The reduction of heat transfer between the annular and central region and the increase of heat transfer between the annular region and ground is the main objective of this study to improve the thermal performance of the CBHE. The results show that the temperature difference between the inlet and outlet of the CBHE rises with the decrease of diameter ratio. In order to reduce costs, instead of using a CBHE with a high diameter ratio and more borehole depth, it is better to use a CBHE with a low diameter ratio and borehole depth. Also, the optimal diameter ratio is calculated for the lowest pumping power. Of course, due to the insignificance of the pumping power against the heat transfer at the different diameters ratio, the CBHE with a lower diameter ratio is recommended because it has better thermal performance and cooling. [ABSTRACT FROM AUTHOR]

Abstract Hollow particle-drag coefficient data is valuable for designing many transport processes. However, limited published work in this regard has motivated us to perform the present work. The present work encompasses experimental terminal velocity, V and estimated drag coefficient, C D of Raschig Ring settling under gravity in Newtonian fluids for 0.2984 ≤ Re ≤ 13, 0.19 ≤ d i /d o ≤ 0.33, 0.22 ≤ d o /D ≤ 0.83 and 40° ≤ θ ≤ 90°. The influence of inner diameter to outer diameter ratio, d i /d o of the Raschig Ring and the ratio of outer the diameter of the ring to channel diameter, d o /D (blockage ratio) on the terminal velocity and drag coefficient are analyzed. The variation of the terminal velocity shows an increasing trend at lower d i /d o and higher d o /D ratios. The terminal velocity becomes higher for higher angle of inclination, θ of the flow channel. The Predictive relation for the drag coefficient is developed as a function of Re , sphericity and the channel inclination. The reliability of the developed models is confirmed by the error analysis. The Raschig Ring experiences higher drag forces than the solid cylinder. The blockage ratio is identified as responsible factor for the appearance of the difference between the present and the litrature drag coefficient data for the vertical channel. The authenticity of the present drag coefficients are therefore examined by comparing it with the theoretical values obtained by numerical simulation using Ansys Fluent v15.0 software. An excellent agreement between the predictive and the current experimental results assures the viability of the RSM model of the simulator. Graphical abstract Unlabelled Image Highlights • Drag coefficient is estimated up to Re = 13 as compared existing literature data 1.8. • The linear variation of C D with both Re and 1/ Re has signified the laminar zone. • Angle dependent correlations for C D are developed as function of Re and sphericity. • Product of C D Re is affected largely by both the viscosity and tube inclination. • RSM model of Ansys Fluent has successfully predicted the experimental C D. [ABSTRACT FROM AUTHOR]

Abstract T-junctions are often used in offshore platforms to partially separate gas from produced fluids. Poorly designed T-junctions frequently produce very high liquid (oil and/or water) carryovers, causing major issues to the downstream equipment train which is not designed to handle excessive liquid. This paper reports the liquid carryover experiments in T-junctions using five different side to main arm diameter ratios under slug flow regime. The obtained phase separation curves can be divided into two component variables; liquid-carryover threshold and peak liquid carryover. The experiments demonstrate that with a decrease in diameter ratio both of these variables decrease. Yet, for superior multiphase flow separation, a high liquid carryover threshold and a low peak liquid carryover are required. Hence, the generally accepted rule that a reduction in diameter ratio improves the phase separation is revealed to be an over-extrapolated statement. The novel findings of this work are: 1) for optimum flow splitting under slug flow conditions, the diameter ratio should be kept between 1 and 0.67, while the diameter ratio 0.67 was found to be most suitable; 2) two correlations were developed for predicting two-phase slug flow separation in different diameter ratio T-junctions. These correlations offer beneficial guidance and clarifications for a number of oil and gas flowline and pipeline applications. Highlights • Separation of two-phase slug flow was experimentally analyzed in five T-junction diameter ratios. • T-junction diameter ratio can only be reduced up to a limit, for improving phase separation. • Two correlations were presented to determine the side arm extraction of operating phases. [ABSTRACT FROM AUTHOR]