Perforation Diameter Research Articles

A wellbore-fracture coupled fracturing model to simulate non-uniform fracture propagation under multiple clusters of fracturing

Multiple clusters of fracturing within one stage have been widely used in the unconventional reservoir production. However, the non-uniform fracture propagation under multiple clusters of fracturing has not yet fully been understood, due to the fluid flow in the wellbore being neglected in the fracturing model. In view of this, a wellbore-fracture coupled fracturing model was established to simulate fracture non-uniform propagation under multiple clusters of fracturing. In this model, the governing equation was firstly given based on the pressure continuity and flow conservation, to obtain the flow distribution in each fracture. Then, equations of fracture propagation, fracture height growth and stress shadow were combined to determine the fracture geometric parameters. Substituting fracture geometric parameters into the governing equation, the wellbore-fracture coupled fracturing model was finally solved. The proposed model was validated by a ABAQUS cohesive elements numerical by comparing the fracture parameters, respectively considering conditions of wellbore-fracture coupling and non-wellbore-fracture coupling, within a maximum deviation that did not exceed 6.14%. Using the proposed model, the parametric analyses were performed, including energy-related parameters and wellbore-related parameters. For energy-related parameters, with the increase of surface energy density of rock and the minimum principal stress, the fracture length and height decreased, while the fracture width increased to some extent. In addition, with the increase of pumping rate of fracturing fluid, the fracture length, height and width increased significantly. For wellbore-related parameters, with the decrease of diameter of perforation and perforation number as well as the increase of wellbore roughness coefficient and viscosity of fracturing fluid and cluster distance, the flow distribution in each fracture and the injection pressure became more uniform and the non-uniform propagation of each fracture was reduced, but fracture dimensions were simultaneously decreased.

Numerical analysis of Plastic Perforated Panel for Acoustic Protection

Acoustic protection is an important aspect in various industrial, commercial and residential applications. In order to reduce the transmission of noise, perforated panels are frequently used as a barrier. The present study aims to conduct a numerical analysis of plastic perforated panels for acoustic protection. The study employed a finite element method (FEM) approach and focused on the propagation of acoustic waves through perforations of varying diameters (30 mm, 40 mm, 50 mm, 60 mm, 70 mm and 90 mm) and at different frequencies (250 Hz, 500 Hz, 1000 Hz and 1500 Hz). The numerical analysis was conducted using the finite element software ANSYS. This work offers numerical analysis models of acoustic wave propagation, which can be used by those interested in similar problems, for different environments, in closed or open spaces. The results showed that the perforation diameter and frequency play a crucial role in the performance of the plastic perforated panels as an acoustic barrier. The results of the author�s research pointed out that the plastic materials can be used successfully in the construction of acoustic barriers. Next to it, the findings of this study can provide valuable insights for engineers and designers in the selection and optimization of plastic perforated panels for acoustic protection applications.

Comparison Between Numerical and an Experimental Results of Pressure Drop in a Perforated Horizontal Wellbore with a 90° Perforations Phasing

Comparison Between Numerical and an Experimental Results of Pressure Drop in a Perforated Horizontal Wellbore with a 90° Perforations Phasing

Investigation of slanted perforation diameter in tabs for supersonic jet control

PurposeThis study aims to investigate the effect of slanted perforation diameter in tabs for the control of Mach 1.4 underexpanded supersonic jet flow characteristics.Design/methodology/approachNumerical investigation was carried out for NPR 5 to analyze the effect of slanted perforation diameter in tabs to control the Mach 1.4 jet. Four sets of tabs with slanted circular perforation geometries (Φp = 1, 1.5, 2 and 2.5 mm) were considered in this study. The inclination angle of 20° (αP) with reference to the jet axis was maintained constant for all the four tabs considered.FindingsDetermined value indicates there is a 68%, 71%, 73% and 75% drop in supersonic core for the Φp = 1, 1.5, 2.0 and 2.5 mm, respectively. The results show that the tabs with 2.5 mm perforation diameter were found to be efficient in reducing the supersonic jet core in comparison with other tab cases. The reduction in supersonic core length is due to the extent of miniscule vortices exuviating from slanted small and large diameter perforation in the tabs.Practical implicationsThe concept of slanted perforation can be applied in scramjet combustion, which finds its best application in hypersonic vehicles and in noise suppression in fighter aircraft.Originality/valueSlanted perforation and circular shapes with different diameters have not been studied in the supersonic regime. Examining the effect of circular diameter in slanted perforation is an innovation in this research paper.

Optimization method of oriented perforation parameters improving uneven fractures initiation for horizontal well fracturing

Horizontal well oriented perforation fracturing is a common technique for unconventional oil and gas production. With the wide application of this technology, issues such as uneven fracture initiation and high initiation pressure appeared, which limited the fracturing effect for unconventional oil and gas. To improve the current situation for oriented perforation fracturing, we establish a numerical model of oriented perforation fracturing for horizontal wells using three-dimensional lattice method. The effects of perforation depth and diameter on fracture initiation pressure, fracture morphology and stimulating area are obtained through numerical simulation. Meanwhile, we propose a depth-controlled and a diameter-controlled oriented perforation design method for uniform fracture initiation. The research results show that, the growth of perforation depth and diameter would lower fracture initiation pressure. Increasing the perforation depth can improve the issue of uneven fracture initiation for oriented perforation fracturing in horizontal wells. Compared with conventional oriented perforation, the depth-controlled and diameter-controlled oriented perforation can significantly improve the uneven fracture initiation issue. The depth-controlled oriented perforation can effectively increase the stimulating area, and induce narrow and long fractures in high elastic modulus formations. The diameter-controlled oriented perforation is suitable for high in-site stress and can reduce fracture initiation pressure. The depth-controlled oriented perforation optimal design is applied to an objective well, Well H-21 of the Chang 73 target layer in Changqing Oilfield, China. Numerical results show that the proposed method can reduce the fracture initiation pressure by 12.6% and increase the fracture area by 11.80%, which can effectively solve the issue of uneven fracture initiation.

Analysis of risk factors for duodenal leak after repair of a duodenal perforation

BackgroundRepairing of a duodenal perforation is a well accepted procedure, but clinically, approximately 4% of patients develop duodenal leaks after perforation repair, increasing the risk of death. We retrospectively analyzed clinical data from 168 patients at our hospital to explore risk factors for duodenal leak after perforation repair and developed a nomogram for predicting postoperative duodenal leak.MethodsThis retrospective case–control study totalled 168 patients undergoing repair of a duodenal perforation with omentopexy at the General Surgery Department, Dongnan Hospital of Xiamen University, from January 2012 to January 2022. The patients were divided into the non-leak group and the leak group. Risk factors were evaluated by analyzing the patient’s sex, shock, diameter and anatomic position of the ulcer, use of NSAIDS and Glucocorticoid, history of drinking, diabetes, chronic diseases, age, time of onset of symptoms and lab tests.ResultOne hundred fifty-six patients (92.9%) who did not develop leaks after repair of a duodenal perforation were included in the non-leak group, and 12 (7.1%) developed leaks were included in the leak group. In univariate analysis, there were significant differences between the two groups referring to age, shock, NSAIDs, albumin, and perforation size (P < 0.05). The area under the ROC curve for perforation diameter was 0.737, the p-value was 0.006, the optimal cutoff point was 11.5, sensitivity was 58.3%, and specificity was 93.6%, the positive predictive value is 41.1%, and the negative predictive value is 98.0%. In the internal validation of the performance of the nomogram, the C-index and AUC of the model were 0.896(95%CI 0.81–0.98), demonstrating that the nomogram model was well calibrated.ConclusionThe study discussed the risk factors for postoperative duodenal leak in patients undergoing repair of a duodenal perforation, and a nomogram was constructed to predict the leak. Future prospective studies with large sample sizes and multiple centres are needed to further elucidate the risk of duodenal leak after repair of a duodenal perforation.

Plate structure optimization and performance study of a new continuous flow electrocoagulation reactor

Electrocoagulation (EC) process is an environmentally friendly and effective water treatment method. A folded plate EC reactor has been developed to remove pollutants such as azo dyes and COD from wastewater. There is a dead zone in the corner position of this electrocoagulation reactor, so this study aims to improve this problem and strengthen the EC mass transfer process in the reactor. A circular perforation treatment at the corner of the folded plate electrode is proposed to promote the exchange between the dead zone and the active zone and enhance the mixing strength. Taking methyl orange as the target pollutant, the effects of perforation diameter, perforation spacing and plate arrangement were considered, and these parameters were optimized by Box-Behnken model. The results show that the removal efficiency of 92.16% is obtained when the perforation diameter is 4 mm, the perforation spacing is 20 mm and the plate arrangement is 0.5 L height difference between the front and back plates. In addition, the RTD curve shows that the dead zone of the perforated electrode is lower, the dimensionless variance is larger, and the mixing effect is better. The cost was reduced by perforation design and optimization of operating parameters, and the COD removal efficiency of 16.8% and the decolorization efficiency of 17.4% were increased in pharmaceutical wastewater.

Assessment of the diagnostic accuracy of strip and furcal perforations in different sizes by cone beam computed tomography.

Root perforation is an adverse event that may accidentally occur during root canal treatment and can adversely affect the treatment plan and tooth prognosis. This study aimed to assess the accuracy of cone beam computed tomography (CBCT) for detecting the strip and furcal perforations with different sizes. The mesiolingual canals of 155 extracted human mandibular first molars were instrumented and randomly divided into four experimental groups and one control group (n = 31). Furcal (in the pulp chamber floor) and strip perforations with 0.5, 1, 1.5, and 2mm in diameter were manually created. The teeth were randomly mounted in bovine ribs and scanned using CBCT. Two radiologists unaware of the study groups observed the images and reported the greatest perforation diameter. The inter-observer agreements were calculated. The diagnostic accuracy was compared for furcal and strip perforations with different sizes. The inter-observer agreement for detecting furcal and strip perforations with different sizes were good. The diagnostic accuracy was 100% for the absence of perforation in each group. CBCT can detect the absence of perforation with high accuracy. The diagnostic accuracy of CBCT in the presence of strip and furcal perforation with different sizes was not significant.

Effect of Antiscalant Usage and Air Diffuser Perforation Diameter on Filtration Performance of Submerged Flat Sheet MBR for Treatment of High Salinity and Scaling Propensity Wastewater

Membrane fouling and mineral scaling remain major drawbacks for MBR technology. Membrane fouling reduces the filtration ability in MBR systems by increasing transmembrane pressure (TMP) and thus increases the operational cost. This study focused on the application of commercially available antiscalant in a pilot MBR system and the effect of diffuser perforation diameter for the treatment of high mineral scaling propensity wastewater. Submerged flat sheet membranes (Kubota, nominal pore size: 0.4 µm) were used in the pilot-scale test unit operated in the wastewater treatment plant of ITOB Organized Industrial Zone, Izmir, Turkey. The commercially available antiscalants employed were coded AS-1 and AS-2 for antiscalant study. Long term effect of the two antiscalants employed was investigated under high mixed liquor suspended solid (MLSS) concentration (17–21 g/L) for two months of MBR operation. The effect of low MLSS concentration (10–13 g/L) was also studied without changing the concentration of antiscalant type and concentration. AS-1 was found to be more effective in terms of mineral scale control. The effect of diffuser perforation diameter (1, 3 and 5 mm) on mineral scaling minimization in MBR pilot system was also studied. The best performance with respect to membrane fouling control was found with an air diffuser having 3 mm of diffuser perforated diameter. Some quality analyses of the product water were also carried out to assess the effect of antiscalant addition on microbial activities in the MBR unit. The findings in this study reveal that the use of antiscalants has not affected biological treatment performance of MBR pilot system. The removal ranges obtained during all MBR studies were 98.47–99.9%, 84.62–99.4%, 89.5–98.5%, 86.90–99.9%, 67.01–99.2%, 75.03–93.9%, and 20.36–71.5% for total suspended solid (TSS), color, chemical oxygen demand (COD), NH4-N, PO4-P, NO2-N, and total nitrogen (TN) respectively.

Dimensionless correlations for estimating the permeability of perforated packaging films to oxygen

Several methods have been applied to estimate the permeance provided by perforations for perforated-mediated modified atmosphere package design. However, no dimensionless correlations have been proposed that comply with the principles of dynamic similarity and could therefore be applied with confidence to different packaging systems. The purpose of this work was to apply the Buckingham π theorem and obtain a generic correlation that obeys the principles of dynamic similarity. A correlation between the Stanton number (St) and the Schmidt (Sc) and Peclet (Pe) numbers was proposed and fitted to a set of 46 datapoints. The results showed that the correlation could be simplified to a proportionality between St and the reciprocal of Pe with a proportionality constant of 0.863. That implied that the influence of the perforation diameter was so dominant that the mass transfer coefficient (which is the same as the permeance given by the perforations) was simply proportional to the reciprocal of the perforation diameter, within the experimental variability. This result was validated with an additional set of 10 experiments. Mass transfer coefficients varied between 1 and 6 cm/s.

Evaluation of the dynamic behaviors of a train braking system considering disc–block interface characteristics

Disc–block interface properties have prominent influence on the dynamic behaviors of train braking systems. In this study, the tribological characteristics of small-scale train friction blocks with different perforation diameters at the centre of the block surface were investigated using a disc–block test rig. And the Stribeck model parameters of the disc–block friction interface were identified to intuitively characterize the evolution law of stick–slip characteristics with the variation of block perforation diameters. Then, a trailer bogie braking system model of a high-speed train considering the coupling effects between the essential brake unit, wheelset and bogie frame was established. And the identified Stribeck parameters were introduced into the proposed braking system dynamics model to establish a relationship between the friction characteristics of the disc–block interface and the dynamic behaviors of the train braking system. Based on this, the cross-scale analysis was performed to evaluate the dynamic performance of a train braking system affected by the perforated friction block via classical stability theory and numerical simulation. The results show that the friction block with a perforation diameter of 3 mm can effectively suppress the stick–slip vibration of the disc–block friction interface, then reducing the oscillation of system components and enhancing the stability of the entire trailer bogie system.

Numerical modeling of shaped charge jet penetration into ceramic–metal double-layered medium using smoothed particle hydrodynamics

The prediction of the damage effects of shaped charge projectile to ceramic–metal multi-layered target is a challenging task to address. In this paper, the smoothed particle hydrodynamics (SPH) method is applied to simulate the penetration of the metal jet generated by the shaped charge detonation into ceramic–metal double-layered plates. The presented SPH model incorporates different equations of states. Moreover, the elastic-perfectly plastic constitutive model and the Johnson–Holmquist-II material constitutive model were employed for modeling the mechanical behaviors of the solid materials in this study. Firstly, simulation of the high velocity impact process of a ceramic ball on a ceramic–metal double-layered plate was conducted to validate the presented constitutive model. After the validation of the numerical model, simulations of penetration of a shaped charge into a double-layered ceramic–metal plate by using millions of SPH particles were conducted. The simulation results (perforation diameter and debris cloud) are in good agreement with the available experimental data, which shows that our in-house SPH solver is capable of tackling the shaped charge detonation and its penetration into multi-layered structures very well. Furthermore, the presented SPH model can reproduce different types of fracture patterns observed in experiments and their dynamic formation processes.

Description of sound absorption by a flat resonator stacking metamaterial with double porosity model

Acoustic metamaterials can be designed by inserting along the path of a sound wave periodically spaced side resonators. An example of efficient design was recently proposed consisting of a perforated stacking of flat annular cavities (the pancake resonator), the perforation allowing the propagation of sound waves. The pancake resonator is used in absorber mode and the theoretical description of sound absorption can be achieved with the help of the theory of sound propagation in fluid saturated porous media in which two porosities are considered: the main porosity associated with the perforation and a porosity associated with the flat cavity volumes. Considering a perforation diameter and flat cavity thickness ranging from submillimetric values to a few millimeters allows a wide range of material permeabilities and permeability contrasts between main pore and stacking of cavities. The relatively small values of diameter and cavity thickness also results in the existence of viscous and thermal boundary layers in the main pore (the perforation) and in the flat cavities. This metamaterial makes simultaneous use of viscothermal losses and periodicity in order to achieve low frequency sound absorption for an overall small absorber thickness. Experimental results are also presented for the validation of the model.

Vibrational damping properties of finite microperforated plates

Microperforated plates (MPP) are traditionally used to advantageously absorb acoustic waves in sound control technologies. However, less is known concerning the additional structural damping they can induce. The latter is activated through exchanges in the viscous and thermal boundary layers near the fluid-structure interface of the microperforations. MPPs therefore offer an alternative to, or can be used together with, viscoelastic materials, commonly implemented to damp vibrations at medium and high frequencies. In this work, the structural damping capabilities of MPP are investigated. To this end, the damping performance of a finite size MPP is explored analytically through an alternative form of the Biot model, classically devoted to porous plates, and considering energy dissipation through viscous friction mechanisms. Analytical results are compared to experimental measurements of structural damping factors on various MPP samples. The model is validated and confirms the damping effect added by the microperforations in the low frequency range. A sensitivity analysis on the perforation rate and perforation diameter provides a condition for which additional damping is maximized.

Experimental analysis of a slant perforated mesh-plate photoreactor for water detoxification

A novel slant perforated mesh-plate photoreactor (SPPR) was designed and fabricated. The central assembly of SPPR was an array of slant perforated mesh-plate coated with TiO2 (P25). The performance of SPPR in water detoxification was evaluated with regard to the degradation of phenol as the target pollutant. The effects of slant plate tilt angle (α) and perforated plate opening aperture diameter on SPPR performance were investigated and analyzed. The photocatalytic performance of SPPR increased with decreasing α. The SPPR with an α of 15° and a pore size of 1 mm showed the best performance with 9.17 h required to reach 80% of phenol degradation (4-L, initial concentration: 15 mg/L). The mass transfer was introduced into the kinetic reaction model, and mass transfer coefficients were calculated for SPPRs with different structures. Flow rate and initial pollutant concentration were investigated for their effects on degradation efficiency. In addition, the activity of SPPR under natural sunlight has also been tested to explore its potential to be applied in practice.

Main factors determining the use of free MS-TRAM and DIEP flaps and comparing the results of breast reconstruction

This study aimed to compare the results of free MS-TRAM and DIEP-flap based on the volume of the transplant and the unique characteristics of blood flow in the tissues. The study included 83 patients, 42 in the MS-TRAM-flap reconstruction group and 41 in the DIEP-flap breast reconstruction group. In the MS-TRAM-flap group, 35 patients received delayed reconstruction, and 7 received one-stage breast reconstruction, including one case of bilateral transplantation. In the DIEP-flap group, 5 patients received one-stage reconstruction, and 36 received delayed reconstruction. Complications associated with the flap tissue were observed in 7 (16.67%) in the MS-TRAM-flap group and 8 (19.51%) cases in the DIEP-flap group. The total level of fat necrosis in MS-TRAM-flap was 7.14% (p=0.033), and in DIEP-flap, it was 9.75% (p=0.039) (2 patients had a substantial amount of fat necrosis, while 2 patients had a modest amount of focal fat necrosis). The number and diameter of perforators (including veins), as well as the transplant volume, are the primary determinants of whether to use a DIEP- or MS-TRAM-flap. DIEP-flap is preferred if there are 1-2 large artery perforators (≥1 mm) and tissue volume of 700-800 grams, while MS-TRAM-flap is used when the tissue volume is significant (>2/3 of standard TRAM-flap).

Numerical study on oxygen transport pattern in porous transport layer of proton exchange membrane electrolysis cells

A transient, two-dimensional and two-phase numerical model is established to study the nature of oxygen transport in proton exchange membrane electrolysis cells (PEMEC). Randomly generated circle fibers are used to construct a patterned porous transport layer (PTL), and the volume of fluid (VOF) method is employed to capture accurate gas-liquid interfaces. The patterns of oxygen transport and the relationship between multiple transport paths are analyzed in detail. We propose for the first time the concept of ‘isolation belt’, which is composed of a series of narrow throats, hindering the spontaneous combination of different oxygen transport paths. The influence of PTL perforation and spatially-graded fiber diameters on oxygen transport are explored. The numerical results show that perforation can probabilistically destroy the ‘isolation belt’, forming a transport path with high priority, which helps to reduce oxygen saturation. Moreover, when the porosity of PTL remains unchanged, reducing the fiber diameter in the region near the catalyst layer (CL) can significantly reduce the local oxygen saturation. The pressure variation reveals its consistency with the maximum throat width of the oxygen transport path, which indicates the law of capillary pressure. From the perspective of mathematical probability theory, a novel functional expression of the profile of oxygen saturation with respect to the structural properties of PTL is proposed to make a concise explanation of gas bubble transport in the context of PEMEC or similar gas-liquid porous flow. The highlights in this paper include: • Comprehensive spatiotemporal profile for in the process of oxygen penetration. • The concept of isolation belt for spontaneous merging of oxygen pathways. • A mathematical explanation for probability of oxygen saturation distribution. • Influence of PTL perforation and graded fiber diameters on oxygen saturation.

Catastrophic Failure Assessment of Sealed Cabin for Ultra large Manned Spacecraft in M/OD Environment

Hypervelocity impacts of Micrometeoroid and Orbital Debris (M/OD) may lead to catastrophic failure of long-term flight manned spacecraft in orbit. Risk assessment for manned spacecraft in M/OD environment is of great significance for the safety of human space missions. For typical catastrophic failure modes of manned spacecraft such as gas-leakage-induced astronaut hypoxia, sealed cabin fracture, and spacecraft breakup, catastrophic failure assessment method using critical perforation diameters and critical crack lengths of sealed cabins and critical fragment size of spacecraft breakup as failure criteria are proposed. In addition, corresponding modules of catastrophic failure assessment were developed and integrated with Meteoroid and Orbital Debris Assessment and Optimization System Tools, providing an effective assessment tool for researching on the safety of manned spacecraft. On the basis of which, catastrophic failure evaluation of sealed cabin for a specific ultralarge manned spacecraft in the M/OD environment was conducted, providing references for on-orbit mission safety evaluation.

Fluid dynamics analysis and optimized throttling design of L-shaped multi-stage high pressure reducing valve

Traditional high-pressure pressure reducing valves are mostly linear, occupying a lot of space and costing a lot. In this study, a L-shaped multi-stage high pressure reducing valve (L-HPRV) is newly designed, it can be widely used in space constrained pipelines, reducing floor space and thus lower costs. Then, the steam flow in L-HPRV is investigated with an experimental validated numerical method. Next, a parametric sensitivity study is conducted to investigate the effects of typical throttling components on fluid dynamics of the newly designed L-HPRV. Finally, based on the parametric sensitivity study, the optimized throttling design of L-HPRV is achieved. The results show that the rhombus-shaped perforated plates is considered to be the first choice for better fluid dynamics. Larger perforated plate diameter (D1/D0) and perforated sleeve diameter (D2/D0) relates to better aerodynamic performance. Chamfer radius has limited effects on fluid dynamics. N-stage adjustable perforated plate effectively disperses the pressure drop and velocity rising gradient in the throttling components at all levels. The preferred level ranking with better fluid dynamics for L-HPRV is obtained.

Experimental evaluation of the effect of perforated spiral fins on the thermal performance of latent heat storage units

The spiral fins are widely employed as an innovative fin configuration in latent heat storage units (LHSU) to improve the poor thermal conductivity of Phase Change Material (PCM). Its persistent annulus promotes heat exchange in PCM, but still interferes with buoyancy-driven natural convection. Perforation is a potential solution to facilitate natural convection. Based on this, the thermal properties of the punctured spiral finned LHSU were experimentally studied. An experimental setup was constructed with three spiral finned LHSUs, two of which were installed with perforated spiral fins with 16 mm and 12 mm perforation diameters. The axial and radial temperature distribution, heat transfer characteristics and efficiency were evaluated for three LHSUs. Experimental results showed that the thermal performance of LHSU was improved remarkably by using perforated spiral fins with higher heat benefits achieved at lower heat transfer areas. The thermal efficiency and average heat flux reached 63.4 % and 1370.7 W/m2 respectively, while the average Nusselt number was 44.0 % higher than that of the solid fin. For the same perforation area, fins with higher diameter perforations achieve superior thermal properties and stronger convective heat transfer, while fins with lower diameter perforations continue to limit natural convection.