Three-dimensional Tube Research Articles

Optimization of Turbulent Flow Heat Transfer in a 3D Cubic Shell Heat Exchanger using Non-Mixture Multiphase Nanofluids

The present work investigates the turbulent flow heat transfer in a three-dimensional cubic shell and tube heat exchanger employing non-mixture multiphase nanofluid, specifically SiO₂-H₂O. Computational Fluid Dynamics (CFD) simulations were carried out to study the variation of both shell and tube inlet velocities and optimize the thermal performance of the exchanger. The Reynolds-averaged Navier-Stokes (RANS) solver and the k-epsilon turbulent model were employed, and the results were validated against experimental data and numerical results from the available literature. Key results showed that reducing the tube’s Reynolds number to 75% of the shell’s inlet velocity yields the highest total heat transfer rate of 26,692 Watt, marking an impressive 54% improvement over the baseline conditions. Lowering the tube inlet velocity improved the fluid residence time leading to enhanced heat absorption and higher performance. However, reductions in either fluid Reynolds number below 75% led to diminished heat transfer rates, attributed to reduced turbulent kinetic energy and less effective thermal mixing. These findings provide valuable insights into the role of nanofluids in boosting heat transfer efficiency, offering practical implications for industries seeking to enhance energy conservation and optimize thermal systems such as air conditioning and heating systems, thermal power plants, automotive and aerospace industries, as well as solar thermal power plants.

Tumor-Derived Immunoglobulin-Like Transcript 4 Promotes Postoperative Relapse via Inducing Vasculogenic Mimicry through MAPK/ERK Signaling in Hepatocellular Carcinoma

Traditional anti-angiogenesis drugs are usually unsatisfactory in hepatocellular carcinoma (HCC) treatment. Therefore, it is urgent to find new precise therapeutic targets and further develop more effective drugs for the treatment of HCC. Vasculogenic mimicry (VM) is different from classical endothelium-dependent angiogenesis and associated with poor prognosis in patients with malignant tumor. However, the mechanism underlying VM occurrence is complex and not fully defined. Immunoglobulin-like transcript (ILT) 4, as a negative regulator of immune response, was recently found expressed in many solid tumors. However, whether and how ILT4 regulate VM remains unclear. In this study, we found VM enriched in HCC tissues especially in tissues from patients who experience relapse within 5 years after surgery. Similarly, ILT4 expression level was also higher in HCC tissues from patients who experience relapse within 5 years after surgery. Linear regression analysis revealed a positive correlation between the expression of ILT4 and VM density. Further, Overexpression/knockdown of ILT4 expression upregulated/downregulated VM related marker, three-dimensional tube formation, the migration and invasion of HCC cell lines in vitro. Mechanistic studies showed that ILT4 promoted VM formation via MAPK/ERK signaling. In conclusion, this study provides a rationale and mechanism for ILT4-mediated postoperative relapse via inducing VM in HCC. The related molecular pathways can be used as novel therapeutic targets for the inhibition of HCC angiogenesis and postoperative relapse.

Effect of a three-dimensional nanotube array substrate on photocatalytic conversion performance of CO2 gas to methanol by amine-loaded CuO/ZnO catalysts

The photocatalytic conversion of CO2 gas into energy-dense hydrocarbons holds the potential to address both environmental and energy problems. Catalysts consisting of CuO clusters/nanoparticles and ZnO nanorods on a metallic nanotube array (MeNTA) silicon substrate were utilized for CO2 reduction. The surface of the catalysts was modified with 3-amino-propyltriethoxysilane (APTES), the amine terminal of which can selectively bind CO2 gas. When photocatalytic CO2 reduction was performed with varying APTES and CuO contents, the highest methanol production of 4.5 mmol/g(catalyst) was obtained at 10 wt% APTES and 7.5 mM CuO contents. The high yield in the present work in comparison with previous reports is due to some advantages of the present catalytic system such as its enhanced activity, significant selectivity, and easy production: Nanometer-sized CuO produced by femtosecond pulse laser irradiation provides a larger active surface per volume and a free surface without a protector, which is favorable for advancing the catalytic activity. The formation of a heterojunction interface in a nanocomposite of p-type CuO and n-type ZnO increases holes at the valence band level of CuO, resulting in advantageous photovoltaic efficiency. The introduction of APTES on the catalyst surface enhances CO2 adsorption and brings about CO2 gas near the catalyst to accelerate the reaction rate. Finally, a three-dimensional tube array on the substrate enlarges the surface per volume for catalyst-loading compared to the two-dimensional substrate. Thus, the proposed catalytic system consisting of amine-loaded CuO/ZnO constructed on a three-dimensional nanotube array substrate is preferable for the photocatalytic conversion of CO2 gas to methanol.

Multi-scale pore model construction and damage behavior analysis of SiCf/SiC composite tubes

SiCf/SiC composite materials are essential for spacecraft thermal protection, determining the safety of spacecraft. However, their complex structures and intricate fabrication processes have led to an unclear understanding of their failure mechanisms, limiting their application. In this study, circumferential compression experiments were conducted, and X-ray computed tomography (X-CT) was used to analyze the distribution characteristics of pore spaces. The experimental results indicate that damage manifests as secondary fracture phenomena based on temporal evolution characteristics. Specifically, after experiencing performance degradation of 24.73–60.96%, the material still maintained basic stability, exhibiting a performance recovery of 31.55–36.1% under the applied load until failure. To predict the dynamic damage behavior of materials at multiple scales, a multi-scale method combining statistical and microscopic approaches was proposed. A micro representative volume element (RVE) random fiber pore distribution model was established based on random processes and random medium theory. Finally, considering the CT data and the principle of minimum potential energy, a macroscopic finite element model of the micro-pores' structural characteristics in a three-dimensional wound tube was reconstructed. The results indicate that cracks initiate around pore defects and gradually propagate to form crack bands. The model closely matches the macroscopic damage and microscopic characteristics of the material. This work provides a new approach for the numerical simulation of pore defects in such materials.

Forced convective rate and pressure drop through a packed annulus: a numerical simulation

Porous materials are used in engineering and industry due to their heat transmission qualities. This study examined forced convection flow through an annular tube packed with sphere balls of various materials and sizes using numerical analysis. The sphere balls were permeable. Ceramic, plastic, and steel with spherical diameters of 3, 5, and 6 and porosity of 0.4 were tested for heat dissipated and fluid flow. Also, test the impact of steel balls of diameter 6mm with 0.6 and 0.8 porosity. The numerical simulation results are used to analyze the forced convection and fluid flow parameters of a three-dimensional annular tube with continuous heat flux in the Reynold number range (5000-14000). Steel balls had an 80% higher heat transfer coefficient than annular tubes without porous mediums. The simulation showed that inserting the porous media increased annular tube pressure loss. The maximum heat transfer coefficient improved by about 80% when the spherical diameter is 3 mm. Also, the result illustrated the heat transfer coefficient of steel balls Increased by about 79%, 69%, and 49%, with 0.4, 0.6, and 0.8 respectively

Influence factors of frictional heat between bristles and rotor for a multi-stage brush seal

Frictional heat generates at frictional surface caused by contact between bristles of brush seal and rotor, which leads to early failure of the seal, especially downstream stage of multi-stage brush seal (MBS). In this paper, a three-dimensional tube bundle model of the MBS was established to study change of heat flux on the frictional surface among stages, internal temperature distribution of bristles and leakage flow characteristics of the seal. Moreover, three control strategies (i.e., increasing height of backing plate to rotor hbp, decreasing interference between bristles and rotor Δr and decreasing axial width of bristle pack wab) were analyzed to further investigate influence mechanism of the frictional heat. Results showed that the frictional heat at bristle tips mainly depend on formation of frictional heat caused by friction between bristle tip and rotor, transfer of heat from upstream stage to downstream one and dissipation of heat with flow of the airflow passing through the seal. For a traditional MBS with same structural single-stage seal units, a remarkable increasing bristle temperature at bristle tip of downstream stage and an increasing vortex area of airflow with higher temperature in chambers implied accumulation of the frictional heat at the downstream stages. Increase of hbp enhanced dissipation of the heat due to increasing passage area of airflow. Both decrease of Δr and decrease of wab obviously reduced bristle temperatures at downstream stages due to decreasing formation of the frictional heat. Furthermore, the decrease of wab had a lower bristle temperature compared to the increase of hbp, indicating a higher impact of the frictional heat formation on bristle temperature at downstage stages.

Topologically optimized flexible tricolor-shape micro-fibre arrayed film and three-dimensional tube display concurrent magnetism, luminescence and conductive aeolotropy

From the perspective of topology design, innovative devise concepts and manufacturing technologies are of great significance for manufacturing high-performance multifunctional composites. Herein, a one-dimensional tricolor-shape micro-fibre was innovatively devised and constructed via a triaxial parallel electro-spinning. As a study case and application, the unique structured [CoFe2O4/polymethylmethacrylate (PMMA)]//[polyaniline (PANI)/PMMA]//[Eu(TTA)3phen/PMMA] magnetic-conductive-luminescent multi-functionalized tricolor-shape micro-fibre arrayed film (marked as MTMAF) were fabricated by orientational arrangement of the tricolor-shape micro-fibres. Meanwhile, magnetic-conductive-luminescent multi-functional quasi tricolor-shape micro-fibre arrayed film (marked as MQMAF) and magnetic-conductive-luminescent multi-functional tricolor-shape nano-strip arrayed film (marked as MTNAF) were also fabricated by alteration of the proportions of solvents. It is further found that MTMAF has better performances than those of MTNAF and MQMAF. The tricolor-shape micro-fibre achieves the partitioning of three separate functional partitions on the microscopic-level through the elaborate topology devise and an electrospinning technology. More importantly, since magnetic, conductive, and luminescent fillings are limited in their subareas, adverse interactions among them can be effectively avoided, resulting in superior poly-functional performances. Since the intense conductive aeolotropism and multifunctionality, MTMAF can be employed as a stable micro-circuit interconnection, offering a foundation for practical applications. Red luminescence can be used to supervise whether MTMAF properly works or not in darkness. Three-dimensional tubes are constructed via crimping the MTMAF in two various modes. The high integration of zero-dimensional nanoparticles, one-dimensional micro-construction blocks, two-dimensional films and three-dimensional tubes is achieved in one material. The construction of three-dimensional tubes achieves the transformation of materials from two-dimension to three-dimension. Furthermore, a universal technique to manufacture micro-fibre/nano-strip with three micro-subareas has been established for constructing multi-functional composites, other functional fillings also can be introduced into the tricolor-shape micro-fibre/nano-strip to achieve different multi-function.

Experimental and Numerical Investigations on Thermal-Hydraulic Performance of Three-Dimensional Overall Jagged Internal Finned Tubes.

To satisfy the demand for efficient heat transfer, a novel three-dimensional overall jagged internal finned tube (3D-OJIFT) was fabricated, using the rolling-ploughing/extruding method. The thermal performance of the 3D-OJIFT were studied and compared in experiments and three-dimensional numerical simulations. The RNG k-ε turbulence model is well verified with the experimental results. By analyzing the distributions of velocity, temperature, and turbulence kinetic energy, it was found that the 3D-OJIFT destroyed the development of the velocity and thermal boundary layers, increased the turbulence disturbance, and reduced the temperature gradient, thus improving the heat transfer. The influences of the jagged height and jagged spiral angle of the 3D-OJIFT are discussed. The Nu and f increased as the jagged height of the 3D-OJIFT increased. The Nusselt number of the 3D-OJIFT was 1.67-2.04 times the value for the smooth tube. In addition, the comprehensive heat transfer performance of the 3D-OJIFT improved after increasing the jagged spiral angle. Compared with conventional internal helical-finned tubes and other reinforcement structures reported in the literature, the 3D-OJIFT demonstrated better comprehensive heat transfer performance. Finally, empirical correlations of the 3D-OJIFT were obtained.

Achieving enhanced multifunctional performance for structural composite supercapacitors by reinforcing interfaces with polymer coating

Carbon fiber structural composite supercapacitors possess the multifunctionality of storing electrochemical energy and withstanding mechanical loads simultaneously, attracting increased attention in electric vehicles, drones, and aircraft sectors. A polymer-based coating was meticulously constructed at the electrode/electrolyte interface to enhance adhesion and stability between active materials and the carbon fiber fabric collector under diverse conditions, especially mechanical stress. Mechanical testing and corresponding physical characterization substantiated the superior performance of the polymer coating. With the protective polymer coating, the optimized structural composite Zn-ion supercapacitor (SZSC), consisting of carbon fiber@active carbon-P (CF@AC-P) cathode, ionogel electrolyte, and Zn anode, displayed a maximum energy density of 164.6 mWh kg−1, at power density of 563.3 mW kg−1. Moreover, the optimized SZSC demonstrated stable operation over more than 8000 cycles at 0.3 mA cm−2 without capacity degradation. The optimized SZSC exhibited a tensile strength of 399.7 MPa and Young's modulus of 11.5 GPa. Furthermore, employing vacuum infusion techniques, the fabricated three-dimensional (3D) wing skin model shell and tube shell curved-surface structural composite Zn-ion supercapacitor component composites showcased exceptional electrochemical performance. These achievements further validate the practicality of 3D multifunctional composites. Consequently, this research presented a practical and straightforward interface engineering approach to develop multifunctional structural devices with remarkable electrochemical and mechanical properties.

Three-dimensional multi-layer carbon tube electrodes for AC line-filtering capacitors

Three-dimensional multi-layer carbon tube electrodes for AC line-filtering capacitors

Predicting shock-induced cavitation using machine learning: implications for blast-injury models.

While cavitation has been suspected as a mechanism of blast-induced traumatic brain injury (bTBI) for a number of years, this phenomenon remains difficult to study due to the current inability to measure cavitation in vivo. Therefore, numerical simulations are often implemented to study cavitation in the brain and surrounding fluids after blast exposure. However, these simulations need to be validated with the results from cavitation experiments. Machine learning algorithms have not generally been applied to study blast injury or biological cavitation models. However, such algorithms have concrete measures for optimization using fewer parameters than those of finite element or fluid dynamics models. Thus, machine learning algorithms are a viable option for predicting cavitation behavior from experiments and numerical simulations. This paper compares the ability of two machine learning algorithms, k-nearest neighbor (kNN) and support vector machine (SVM), to predict shock-induced cavitation behavior. The machine learning models were trained and validated with experimental data from a three-dimensional shock tube model, and it has been shown that the algorithms could predict the number of cavitation bubbles produced at a given temperature with good accuracy. This study demonstrates the potential utility of machine learning in studying shock-induced cavitation for applications in blast injury research.

Direct numerical simulation of supersonic nanoparticles flow in free-molecule regime using the angular coefficient method

We employ molecular flow methods to numerically simulate the supersonic nanoparticles flow in free-molecule regime. To streamline the computational complexity, interaction forces between the gas and solid particles are disregarded. We first develop a discrete phase model (DPM) method that integrates the non-rigid body collision model, enabling an accurate simulation of nanoparticle diffusion under the influence of the drag force and Brownian motion force. The nanoparticles considered in this study have sizes below 10 nm, and the accuracy of the DPM method is verified by comparing its results with experimental data. Subsequently, we theoretically and numerically investigate the transmission probability and number density of N2 molecules flowing through two-dimensional (2D) channels and three-dimensional (3D) tubes by using the angular coefficient (AC) method and the direct simulation Monte Carlo (DSMC) method. The findings indicate that as the diameter of the nanoparticle (dp) decreases to 1 nm, the diffusion coefficient (D) and the root mean square displacement (x) of nanoparticles approach the N2 molecules. The microscopic velocity of most N2 molecules falls within the range of 62–1400 m/s, and the macroscopic velocity of N2 flow falls within the range of Ma = 1.28–1.35. In contrast to the DSMC method, the AC method exhibits enhanced accuracy even with a reduced number of grids and obviates the process for large-scale sampling. Additionally, the solution time required by the AC method is approximately 1/10 and 1/13–1/32 of the DSMC method in 3D cylindrical tubes and 2D channels, respectively. Moreover, the AC method demonstrates superior adaptability when dealing with complex geometries.

CONDENSATION HEAT TRANSFER IN SMOOTH AND THREE-DIMENSIONAL DIMPLED TUBES OF VARIOUS MATERIALS

The heat transfer and pressure drop of R410A and R32 within a smooth and an enhanced dimpled tube were measured for mass fluxes from 100 to 400 kg m<sup>-2</sup> s<sup>-1</sup>, average vapor qualities between 0.2 and 0.8, and saturation temperatures between 35°C and 45°C. The test section was 2 meters in length, and the outer and inner diameters of the tube were 9.52 and 8.32 mm, respectively. The inner surface of the enhanced tube was dimpled. Three dimpled tubes and three smooth tubes, differing by material (copper, aluminum, and stainless steel) were tested to examine the material effect. The measured condensation heat transfer coefficient (HTC) for the copper smooth tube was 1.10 to 1.16 times higher than that of the aluminum, and likewise, between 1.19 and 1.31 times higher than that of the stainless-steel tube. Similarly, the condensation HTC for the copper dimpled tube was 1.06 to 1.15 times higher than that of the aluminum dimpled tube, and 1.26 to 1.38 times higher than that of stainless-steel dimpled tube. In general, and the condensation HTC for R32 was greater than that for R410A, mainly due to the greater liquid thermal conductivity of R32. Flow patterns were observed for different vapor qualities and used to establish corresponding heat transfer mechanisms. Finally, a new correlation for dimpled tubes was proposed based a modified smooth tube correlation, which predicted the measurements within an error band of 20&#37.

WKB analysis of the bifurcation for a three-dimensional neo-Hookean cylindrical tube under restricted compression

We study the bifurcation of a three-dimensional neo-Hookean elastic cylindrical tube under axial compression, where the movement of the outer surface is restricted. For the first time, the WKB method is applied to the three-dimensional eigenvalue problem and the bifurcation conditions are calculated for thick and thin-walled cylinders, separately. In this paper, two WKB expansions are considered for the two cases (i.e. for large axial or circumferential mode number) and the asymptotic expansion of the eigenvalue is obtained for each case separately. It is found that the changes of the axial stretch relative to the thickness of the cylinder have a boundary layer structure. The dependency of the axial stretch on the mode numbers, length and the wall thickness is assessed. The critical stretches occur for the finite critical mode numbers and are an decreasing function of the thickness of the tube, so thick cylinders are easier to buckle. Also, transitions between axial and circumferential modes occur in three points for mode numbers of 10,20 and at a point for mode number of zero. Using the compound matrix method to verify the analytical results, the comparison of outcomes of the numerical and analytical data shows a good agreement.

On the unsteady cavitation characteristics of compressible liquid nitrogen flows through a venturi tube

In this paper, the unsteady cavitating flows of liquid nitrogen (LN2) through a three-dimensional (3D) venturi tube in different thermal cavitation modes are modeled based on the mixture multiphase model with the LES method and Sauer-Schnerr cavitation model. A numerical framework considering compressibility and the thermal effects of cryogenic fluids is developed, and the modified temperature-dependent Tait equations of state provide the mathematical closure. The numerical results are compared with those from previous experiments that we have conducted, and it is indicated that the simulations and experiments agree well. Condensation shock wave propagation is observed to be initiated by the impingement of the collapse-induced pressure waves from the previously shedding cloud, and details of the process are presented. The impacts of the thermal effect on the cavitation dynamics, especially the evolution of cavitation patterns and dynamic interactions between cavitation and vortex, are analyzed. The numerical results show that the formulation of condensation shock generated at the rear of the cavity varies with temperature. In addition to the pressure waves caused by shed vapor collapse, the violent mass transfer process at the closure region of the cavity releases a substantial quantity of latent heat, initiating further condensation towards the cavity as liquid temperature decreases. The entropy production theory is derived and implemented, and different entropy production terms are established in unsteady LN2 cavitating flow with different thermal effects to understand the interactions between cavitation and entropy production. The present study provides insight into the interactions of cavitation-condensation shock in the LN2 cavitating flow and contributes to a better understanding of the influences of thermal effects on cryogenic cavitation dynamics.

Studying Angiogenesis Using Matrigel In Vitro and In Vivo.

Angiogenesis plays a critical role in physiology and pathophysiology of the human body; hence, it is important to explore the methods to study angiogenesis under in vitro and in vivo settings. Here, we describe three different methods to assess angiogenesis using Matrigel: an in vitro two- or three-dimensional (2D/3D) tube formation or angiogenesis assay using endothelial cells with growth factor supplemented Matrigel, an ex vivo sprouting angiogenesis assay embedding aortic rings in the Matrigel, and finally, Matrigel plug assays wherein Matrigels are implanted into the flanks of mice to assess the recruitment of endothelial cells to form new blood vessels in vivo.

A modular continuous robot constructed by Miura-derived origami tubes

Folding a flat sheet under a specific crease pattern can form a three-dimensional origami tube, which has been proven to exhibit unique mechanical properties and has wide engineering applications. In this study, a novel Miura-derived origami tube is designed, and its precise circular closing condition and mechanical properties are systematically analyzed, revealing that the proposed origami tube has programmable stiffness characteristics. Polyvinyl chloride (PVC) sheet enables the origami tube to have the characteristics of flexibility, bending, compression, and torsion resistance. Then, a modular design strategy for the novel continuous robot constructed with the Miura-derived origami tube as the backbone is proposed. A continuous robot with three origami tube modules in series is designed and fabricated as a representative case. Three steel wires drive each module to achieve independent contraction or bending movement. The unified installation of steel wire-driven motors on the base endows the robot with a lightweight, interconnected inner space, high scalability, and flexibility backbone. The kinematic relationships among the driving space, configuration space, and task space are investigated by geometric model and constant curvature assumption, with the circular trajectory tracking and reachable workspace revealed by numerical simulations. Further, the kinematic decoupling or the multi-driving model based on the stiffness difference of the origami tube between multi-segments is discussed. Finally, three prototype experiments demonstrate both the rationality of introducing origami tubes to design the continuous robot and the application potential.

Influence of pH value on tube formation of human dermal microvascular endothelial cells and its molecular mechanism

Influence of pH value on tube formation of human dermal microvascular endothelial cells and its molecular mechanism

X-ray microtomography analysis of the damage mechanisms in 3D circular braided carbon fiber/epoxy resin composite tubes under axial impact compression

The dynamic behavior of three-dimensional (3D) circular braided composite tubes with different braided parameters was experimentally investigated subjected to axial impact compression using a Split Hopkinson Pressure Bar (SHPB). The damage characterization of the post-impacted tubes was examined using scanning electron microscope (SEM) and X-ray micro-computed tomography (micro-CT). The influence of braided parameters and strain rate, including braided angle, the number of braided layer and axial yarn, on the dynamic mechanical properties, progressive crush characteristics and failure mechanism of 3D braided composite tubes was analyzed in detail. It was found that the smaller braided angle and the larger numbers of braided layers contributed to better axial dynamic properties. The compressive strength, stiffness and specific energy absorption (SEA) of 3D five direction (3D5D) tubes with axial yarn were larger than those of 3D four direction (3D4D) tubes without axial yarn. Meanwhile, the dynamic mechanical response and damage patterns of braided tubes exhibited significant strain rate effects. The impact compression failure mechanisms of braided tubes were mainly fiber tows crushing, fiber breakage, fiber buckling, shear fracture, resin cracking, interfacial cracks, fiber-matrix debonding, etc.

Multi-scale Progressive Damage and Failure Behavior Analysis of Three-Dimensional Winding SiC Fiber-Reinforced SiC Matrix Composite Tube

Multi-scale Progressive Damage and Failure Behavior Analysis of Three-Dimensional Winding SiC Fiber-Reinforced SiC Matrix Composite Tube