Rib Pattern Research Articles

Effects of turning vane on flow control and heat transfer in ribbed two-pass channel with varied rib patterns

Faced with the escalating cooling requirements of turbine blades, two-pass channels with ribs on the internal surfaces have been extensively employed to enhance internal wall heat transfer. Considering the potential to mitigate flow separation and pressure losses generated by channel curvature, in this study, a computational fluid dynamics approach based on the realizable k-ε turbulence model is employed to explore the effects of turning vane introduction on the flow and heat transfer characteristics of two-pass channels with varying rib configurations. The rib configurations are identified as NN, NP, PP and PN. “N” denotes the ribs rotated 45° clockwise relative to the flow direction, while “P” denotes the ribs rotated 45° counterclockwise. The results indicate that the introduction of turning vanes improves the flow uniformity in the downstream channel of the two-pass channel with N-patterned upstream ribs, enhancing inter-rib heat transfer in the downstream channel. It also strengthens the heat transfer performance at the bend region of the two-pass channel with P-patterned upstream ribs. Furthermore, the introduction of turning vanes results in a decrease in friction loss factor for two-pass channels with various rib arrangements at varying levels of Reynolds numbers. The reduction is more pronounced in the two-pass channel featuring N-patterned upstream ribs, with a maximum decrease of 18.6 %. In contrast, the decrease is only 5.2 % in the PP-patterned rib channel. Additionally, the thermal performance factor of NP-patterned and NN-patterned rib channels increases by 8.5 % and 8.7 % respectively after the insertion of turning vanes. However, the enhancement is limited in the PP-patterned and PN-patterned rib channels.

Experimental studies on bond behaviour of steel rebar with different rib patterns in concrete

The bond between concrete and steel rebar is one of the most crucial parameters in the construction of reinforced concrete structures. The load-bearing capacity and serviceability of these structures depend heavily on bond strength. The rib pattern of the rebar plays a significant role in enhancing bond behaviour. The impact of different rebar patterns on bond studies in the concrete mix is found to be limited. In the study, six concrete mixes were prepared and tested. Three of these mixes incorporated fly ash in varied amounts to partially replace cement, while the other three mixes had no fly ash. Three different rib patterns of steel bars were embedded into these six grades of concrete. The pull-out tests were used to assess the bond strengths of various combinations in accordance with RILEM recommendations. The findings show that the ribs in rebars significantly increase mechanical interlocking whereas the presence of fly ash improves chemical adhesion in bond behaviour. Particularly, pattern 2 rebar (transverse rib thickness, 0.797 mm; transverse rib width, 2.06 mm; rib spacing (inner to inner), 6.428 mm; longitudinal rib thickness, 1.04 mm; longitudinal rib width, 2.312 mm; rib inclination angle, 66.39o; nominal diameter, 16 mm; length of transverse rib, 25 mm) exhibited notably superior bond strength, reaching a maximum of 17.21 MPa in M30 grade concrete in which 95 kg/m³ of fly ash was used as a replacement for cement.

Spatiotemporal distribution and morphological diversity of the Cambrian Wiwaxia: New insights from South China

Wiwaxia is a well-known Cambrian animal and a relative of annelids and molluscs, characterized by its densely arranged, imbricated dorsal sclerites. Despite its prevalence in the fossil record, the scarcity of articulated specimens leading to persistent uncertainties regarding its morphological diversities and evolutionary history has fueled ongoing investigations. This study presents an additional articulated specimen and isolated sclerites from the Cambrian Stage 4 Douposi Formation in Yunnan Province, South China, representing a new species—Wiwaxia douposiensis sp. nov. The newly described materials, originating from a new Cambrian Konservat-Lagerstätte, exhibit typical Burgess Shale-type preservation. They unveil a distinctive two-order rib pattern and aspect ratios of sclerites. The temporal and spatial distribution of Wiwaxia suggests a potential origination centered in South China during the Cambrian Age 3, with an expanding pattern from shallow to deep waters and from warm-humid to dry-cold climates during the Cambrian Age 4 to Drumian. Statistical and phylogenetic analyses highlight the dual aspects of conservative aspect ratios in sclerites, and morphological variations observed at the species levels within Wiwaxia.

Mesh-based topology, shape and sizing optimization of ribbed plates

In this paper, we present a new parameterization and optimization procedure for minimizing the weight of ribbed plates. The primary goal is to reduce embodied CO2 in concrete floors as part of the effort to diminish the carbon footprint of the construction industry. A coupled plate-beam finite element model and its computational mesh enable simultaneous topology, shape and sizing optimization of ribbed plate systems. Using analytical sensitivity analysis and gradient-based optimization, we achieve significant weight reductions in the range of 24–57%, in comparison to reference designs with regular ribbing patterns. The results strengthen the argument in favor of ribbed plates as a structural system that can serve the environmental goals of the construction industry. While our focus is on ribbed concrete plates in buildings, the proposed mesh-based design parameterization is applicable in the general case of optimizing stiffened shells—with potential contributions also to automotive and aerospace applications. All computer codes used in this study are freely available through a public repository, https://zenodo.org/records/11489996.

Investigation on energy, economic, and environmental aspects of double-pass solar air heater.

Numerous research studies have found that a double-pass solar air heater (DPSAH) performs better than a single-pass solar air heater (SAH). This suggested study aims to evaluate the performance of a DPSAH setup in Southern Tamil Nadu, India. Several artificial roughness features have been incorporated into the solar black-coated absorber plate for this examination. Broken ribs with semi-circular and semi-polygonal shapes are used and explicitly tested on the absorber plate. Next, the efficiency of these rib designs is contrasted with a typical flat plate DPSAH. These studies also employ three different mass flow rates (0.01kg/s, 0.02kg/s, and 0.03kg/s), enabling a thorough assessment of the DPSAH system's performance at each rate. These studies' findings demonstrate that adding artificial roughness to the solar collector plate has a beneficial effect on the turbulence of fluid flows. As a result, this innovation increases the double-pass solar air heater's (DPSAH) heat transfer rate. It is noteworthy that compared to the DPSAH with flat plates, both rib designs perform better. It is important to remember that the semi-polygonal ribs function better than the semi-circular ones. The average efficiency values for the semi-polygonal rib structure are 17.1%, 18.7%, and 19.1% greater than those seen for flat plates. These efficiency values are additionally 4.4%, 7.4%, and 8.7% higher than those attained with the semi-circular rib topologies at flow rates of 0.01kg/s, 0.02kg/s, and 0.03kg/s, respectively. The study goes into considerable detail on how particular rib patterns can be advantageous economically and environmentally.

Stiffening patterns for freeform composite shell structures

This paper investigates innovative approaches for enhancing the structural integrity of form-found shell structures with a focus on rib-based reinforcements. It discusses the significance of ribs in enhancing stability and addressing the sensitivity of form-found structures to various loads. Traditional methods such as increasing shell thickness or introducing supports often compromise efficiency and aesthetics. A more intelligent approach involves reinforcing the shell with ribs and advanced materials. Diverse rib patterns are presented, including geometric, biomimetic, and topological optimization-inspired designs, each adhering to a 50 % volume constraint, when compared to the original shell. Physical testing and numerical simulations demonstrate that these rib patterns significantly increase stiffness and buckling resistance. The findings presented in the paper suggest that combining form-finding methodologies with well-designed rib patterns can create sustainable and resilient structures, contributing to a reduction in both the consumption of materials and the environmental impact of these structures.

Development of correlations of Nusselt number and friction factor of solar thermal collector equipped with hybrid rib roughness

In this advanced and comprehensive research, a pioneering hybrid rib configuration, amalgamating arc and V-shaped ribs, is precisely engineered to delve into the complex synergistic effects between this cutting-edge rib design and the heat transfer and fluid flow behavior within a solar thermal collector (STC) specifically utilized for direct air heating. The focal point of this investigation is the impact of the rib pattern on pivotal performance indicators, notably the Nusselt number (Nu) and the friction factor (f). This specific rib roughness design emanates from an exhaustive analysis of a spectrum of non-dimensional roughness parameters: the arc angle (α), the attack angle (β), the relative positioning of the V ribs (D/w), the relative spacing of the ribs (p/e), and the rib height (e/D). These parameters are studied within defined ranges: 30̊‐60̊, 30̊‐60̊, 0.2–1, 8–12, and 0.023–0.043, respectively. The results of highlight a significant improvement in heat transport, as indicated by a significant increase in the Nusselt number (Nu), which has risen impressively by a factor of 3.08. Furthermore, this paper presents development of correlations for Nu and f, taking into account the roughness parameters of the hybrid ribs and the flow Reynolds number, in order to precisely forecast these key performance measurements.

Enhancing recuperators performance in supercritical CO2 Brayton cycle of solar power plants through ribbed heat transfer plates

Sixteen diverse combinations of ribbed heat transfer plates (HTPs), comprising continuous and discontinuous rib configurations, are investigated as potential replacements for traditional smooth HTPs in both the low-temperature recuperator (LTR) and high-temperature recuperator (HTR) of supercritical CO2 Brayton cycles. The findings indicate that the impacts of the introduced HTPs are more significant under the operating conditions of the LTR than those of the HTR. Generally, the incorporation of denser ribs at the upstream sections of both the hot and cold flow paths leads to a significant enhancement in j-factor values. On the hot side of the LTR, these increases exceed 60%, while on the cold side, they surpass 40%. It is also observed that variations in rib pitch exert a more substantial influence on thermal performance compared to alterations in rib length. When comparing non-uniform rib patterns, it is found that the use of ribs with variable lengths increases f-factor values, whereas the design of HTPs with variable rib pitches decreases these values. The design of HTPs with a non-uniform arrangement of rib pitch yields the best overall performance in the LTR. The performance index values for the hot-side and cold-side of this model reach 1.39 and 1.26, respectively.

Mechanism of branching morphogenesis inspired by diatom silica formation

The silica-based cell walls of diatoms are prime examples of genetically controlled, species-specific mineral architectures. The physical principles underlying morphogenesis of their hierarchically structured silica patterns are not understood, yet such insight could indicate novel routes toward synthesizing functional inorganic materials. Recent advances in imaging nascent diatom silica allow rationalizing possible mechanisms of their pattern formation. Here, we combine theory and experiments on the model diatom Thalassiosira pseudonana to put forward a minimal model of branched rib patterns-a fundamental feature of the silica cell wall. We quantitatively recapitulate the time course of rib pattern morphogenesis by accounting for silica biochemistry with autocatalytic formation of diffusible silica precursors followed by conversion into solid silica. We propose that silica deposition releases an inhibitor that slows down up-stream precursor conversion, thereby implementing a self-replicating reaction-diffusion system different from a classical Turing mechanism. The proposed mechanism highlights the role of geometrical cues for guided self-organization, rationalizing the instructive role for the single initial pattern seed known as the primary silicification site. The mechanism of branching morphogenesis that we characterize here is possibly generic and may apply also in other biological systems.

A new asymmetric rhynchonellide from the Cretaceous of the Eastern Prebetic (Southeastern Spain)

The external and internal features and the microstructure of the asymmetric rhynchonellides from the Albian–Cenomanian (Cretaceous) transition from the Alicante Province (Eastern Prebetic, Southeastern Spain) have been herein studied. Previous authors placed these rhynchonellides in Cyclothyris difformis, consequently attributing an unquestionable Cenomanian age (Upper Cretaceous) to the deposits in which they appear. The long dorsally concave crura and the leptinoid pattern microstructure of the shell confirm their attribution to the genus Cyclothyris. However, among other diagnostic criteria (e.g., ribbing pattern, relative width), C. difformis shows facultative type of asymmetry; while the forms studied here show obligate asymmetry. Therefore, the new species Cyclothyris ementitum sp. nov. is formally described, being characterized by the biconvexity of its shell, its obligate type of asymmetry and an ornamentation of around 25 ribs on each valve. Thus, the study and revision of these rhynchonellides has contributed to updating the record and distribution of the asymmetric Cretaceous rhynchonellides of the genus Cyclothyris. This work opens a new line of research to better understand the biostratigraphical calibration of the Cretaceous sediments from the Eastern Prebetic, and a new insight into the possible origin of the obligate asymmetry present in C. ementitum.

Experimental investigation on jet impingement heat transfer analysis in a channel flow embedded with V-shaped patterned surface

ABSTRACT Heating and cooling systems benefit from jet impingement as it increases efficiency while reducing operating costs. The combined methodology, integrating jet impingement and passive heat transfer through the use of roughened surfaces, offers significant potential for improving heat transfer. This research presents the results of an experimental study on a channel flow commonly used for air heating, known as a solar air heater (SAH), with impinging air on the heated surface. The surface is embedded with V-shaped ribs as turbulence promoters, and it receives a continuous heat flow of 1,000 W/m2. Various design combinations were tested experimentally, including streamwise pitch ratio X/Dh = 0.866, spanwise pitch ratio Y/Dh = 0.866, jet diameter to hydraulic diameter ratio Dj/Dh = 0.065, and an angle of attack (α) ranging from 45° to 90°. During these experiments, the Re varied from 3,500 to 18,000. The optimal improvement was observed at values of X/Dh = Y/Dh = 0.866, Dj/Dh = 0.065, and α = 60°. This paper presents novel findings demonstrating that incorporating V-shaped rib patterns in SAHs can yield Nusselt numbers up to 5.2 times higher than those in smooth duct SAHs, offering substantial potential for enhanced energy efficiency. When the entering jet impacts and flows along the ribs of the absorber, the findings suggest that the V-shaped ribs accelerate the flow, resulting in enhanced heat transfer. All datasets were also analyzed for their thermo-hydraulic performance, with the maximum value recorded as 3.301 within the constraint range used in this analysis.

Novel SOFC Repeating Unit Design for the Uniform Distribution of Temperature and Thermo-Electrochemical Reaction Zone in a Commercial Scale Stack

Despite the substantial benefits provided by solid oxide fuel cell (SOFC), its low durability at high-temperature hydrocarbon-fueled operations has inhibited widespread market deployment. Thanks to the tremendous efforts of researchers, SOFC has exhibited sufficient performance to compete with other power generation technologies in the market. However, the lifespan problem due to long-term degradation remains the final obstacle for large-scale deployment. Especially when the hydrocarbon is used as fuel to take an advantage of fuel flexibility, carbon deposition can worsen the problem.A conventional crossflow type stack has the advantage of small volume, which can increase the power and energy density, but suffereing from large nonuniformities of temperature and thermo-electrochemical reactions. However, it has nonuniform temperature and species distribution, where thermo-electrochemical reactions are concentrated at the fuel inlet region. These imbalanced distributions of temperature and species are the major limitation of conventional design since certain regions of the stack are inevitably exposed to a much harsher environment than the remaining regions. For example, nickel reoxidation may occur where fuel is depleted, interfacial separation due to high polarization may appear where electrochemical reactions are concentrated, and carbon deposition may be developed where thermochemical reactions extremely occur. These specific regions might be degraded much faster than the remaining, which can threaten the entire stability of the stack.In this study, we present the novel SOFC stack design that can solve the instability problem of the conventional crossflow type design. First, the vertical gas manifold holes are rearranged to be placed in all perimeters, symmetrical in both diagonals [1]. Since this arrangement makes the stack consist of four symmetric parts, all thermodynamic variables and chemical reactions are distributed symmetrically, and the temperature gradient in the planar direction can be reduced. Second, the guide rib pattern and flow resistance field in the interconnect are optimized to have uniform gas distribution [2]. Finally, a new component, called a ‘cover’, is added in between the interconnect and cell to control the mass transport in a vertical direction [3]. Through the control of mass transport in the vertical direction, chemical reactions can occur in much larger regions rather than concentrated in the fuel inlet regions. To verify the advantages of the novel design, we compare it with the conventional design through the three-dimensional numerical model [4]. As shown in Figure 1, the nonuniformities of temperature, fuel concentration, and chemical reaction are improved through the design modification. Compared to the conventional design, the standard deviations of each variable in the novel design are decreased by 65.07%, 25.14%, and 20.28%, respectively. Entire design processes, various simulation results, and detailed analysis will be provided.

An Analytical Solution on Vibration Reduction and Shear Force Mitigation of Cantilever Mindlin Plates Using Orthogonal Ribs

Vibration of aircraft wings and the dynamic stress concentration at the clamped edge are important research topics due to concerns on the safety of aircrafts. To have a better understanding of the problem, the free and forced vibration response of a ribbed rectangular cantilever plate representing a section of an aircraft wing is investigated in this study. A new analytical solution is developed for the vibration analysis of rib stiffened cantilever plates using Mindlin plate and Timoshenko beam theories alongside the finite integral transform technique. The one- and two-dimensional integral transforms are applied to the governing equations of beams and plates, respectively, where the coupling force components at the interface between the base plate and the beam(s) can be automatically defined during the integral transform. Eventually, the partial differential equations are transformed into a system of linear algebraic equations in which its derivation is rigorous and easily implemented. Good agreements are found between the results of analytical solution, finite element analysis (FEA) and related literature. The solution is then employed to study the vibration suppression of cantilever plates and the shear force at the clamped edge. It is found that the insertion of a pair of orthogonal ribs in the plate can effectively reduce its vibration. An optimum orthogonal ribbing pattern is obtained using multi-objective particle swarm optimization (MOPSO) algorithm, taking into consideration both the vibration suppression of the plate and the maximum induced shear force at the corners of the clamped edge.

Topology optimization of rib patterns for a freeform composite structure

This paper presents an algorithm for the design of efficient and stable composite freeform shell structures. The design workflow combines form-finding, structural analysis, and optimization techniques. To illustrate it, the paper provides a case study of the design and optimization of carbon fiber-reinforced polymer shell. After form-finding of the the initial structural shape, topology optimization was conducted to develop the reinforcing rib pattern to increase its buckling resistance. The use of optimized rib layouts greatly increased the rigidity of the shell, which was confirmed by finite element simulations.[copyright information to be updated in production process]

Hybrid manufacturing by additive friction stir deposition, metrology, CNC machining, and microstructure analysis

Aerospace flight panels must provide high strength with low mass. For aluminum panels, it is common practice to begin with a wrought plate and remove the majority of the material to attain the desired structure, comprising a thinner plate with the desired pattern of reinforcement ribs. As an alternative, this study implements hybrid manufacturing, where aluminum is first deposited on a baseplate only at the rib locations using additive friction stir deposition (AFSD). Structured light scanning is then used to measure the printed geometry. This geometry is finally used as the stock model for computer numerical control (CNC) machining. This paper details the hybrid manufacturing process that consists of: AFSD to print the preform, structured light scanning to generate the stock model and tool path, three-axis CNC machining, and post-process measurements for part geometry and microstructure.

Bond-slip response of corroded SD bars with recycled coarse aggregate concrete

Recycled aggregate concrete (RAC) has been the subject of numerous research to ensure the efficient use of aggregates made from recycling old concrete by examining various parameters in fresh and hardened phases. The present study investigates the bond-slip response of Recycled coarse aggregate concrete (RCAC) with Super Ductile (SD) reinforcing steel exposed to corrosion with varying degrees. SD rebar category is relatively new compared to the hot-rolled and TMT classes of reinforcing steel. SD has a superior bonding performance with concrete owing to the distinctive rib patterns. RILEM-specified cylindrical pull-out specimens were fabricated with RCA concrete with replacement ratios of (0%, 25%, 50%, 75%, and 100%) and centrally embedded SD bars. Pull-out specimens were immersed in NaCl solution before exposure to impressed current corrosion to achieve desired levels of corrosion. The specimens were tested for failure in a displacement-controlled Pull-out testing universal testing machine (UTM). A set of linear variable displacement transducers (LVDT) recorded the slip of the rebar at both the loaded and unloaded ends. The bond-slip response was used to characterize the overall behavior of the bond mechanism. Predictive models have been suggested for the bond strength of RCAC following corrosion. The results indicate that the bond strength of RCAC is almost similar to that of the natural aggregate concrete (NAC) exposed. The results indicated that both the bond slip and bond degradation hold good and agree with previous models. The findings can help anticipate the performance of structural elements made of recycled coarse aggregate concrete (RCAC) exposed to aggressive environments.

Three-Dimensionally Printed Expandable Structural Electronics Via Multi-Material Printing Room-Temperature-Vulcanizing (RTV) Silicone/Silver Flake Composite and RTV.

Three-dimensional (3D) printing has various applications in many fields, such as soft electronics, robotic systems, biomedical implants, and the recycling of thermoplastic composite materials. Three-dimensional printing, which was only previously available for prototyping, is currently evolving into a technology that can be utilized by integrating various materials into customized structures in a single step. Owing to the aforementioned advantages, multi-functional 3D objects or multi-material-designed 3D patterns can be fabricated. In this study, we designed and fabricated 3D-printed expandable structural electronics in a substrateless auxetic pattern that can be adapted to multi-dimensional deformation. The printability and electrical conductivity of a stretchable conductor (Ag-RTV composite) were optimized by incorporating a lubricant. The Ag-RTV and RTV were printed in the form of conducting voxels and frame voxels through multi-nozzle printing and were arranged in a negative Poisson's ratio pattern with a missing rib structure, to realize an expandable passive component. In addition, the expandable structural electronics were embedded in a soft actuator via one-step printing, confirming the possibility of fabricating stable interconnections in expanding deformation via a missing rib pattern.

An experimental and numerical investigation of energy absorption of sportswear in seam area

This study aims to investigate the energy absorption of seam areas in sportswear. Weft knitted fabrics with two structures of plain and rib were fabricated by polyester/Lycra and viscose/ Lycra yarns. Fabrics were stitched in two stitch classes. Moreover, two types of seams were considered. A pull-out test was carried out on all samples to determine the energy absorption values. Furthermore, a finite element model was applied to predict the energy absorption of each structure. The unit cell of each sample was created in ABAQUS software and the tensile load was applied to the stitch yarn. The unit cells of the fabric and the stitched section were modeled in the meso-scale and then elastic and viscoelastic properties of the yarns were assigned to the model. The energy absorption of the sample with rib pattern, lapped seam, and 607 stitch class was more than other samples. Also, the numerical and experimental results showed a high correlation with each other in samples with 304 stitch class and flat seam type.

First occurrence of the rare middle Jurassic ammonite genus Erymnocerites Jeannet from southern Poland

ABSTRACT The genus Erymnocerites Jeannet is recorded for the first time from Poland. A single specimen, assigned to Erymnocerites argoviensis Jeannet is recorded from the Callovian Lamberti Zone from the Ogrodzieniec quarry (southern Poland). It is associated with upper Callovian forms of Peltoceras schroederi, Kosmoceras duncani and Quenstedtoceras lamberti. However, this condensed bed also yielded lowermost Oxfordian species of Peltoceratoides (Peltoceratoides) williamsoni, Peltoceratoides (Parawedekindia) arduennensis, Euaspidoceras subbabeanum, E. babeanum, Bukowskites minax, Cardioceras spp. and Hecticoceras (Putealiceras) punctatum, suggesting a condensation spanning the uppermost Callovian to lowermost Oxfordian for the lower beds at the Ogrodzieniec quarry. The recorded specimen differs from the middle Callovian Coronatum Zone E. argoviensis, which is a much larger (still septate at 188 mm), more depressed, less evolute, and has a rounded whorl section. However, based on the similarities in septal suture line and ribbing pattern, and considering the morphological variations in pachyceratids, the Polish specimen is referred to E. argoviensis. Based on the size difference between the Herznach (Switzerland) holotype of E. argoviensis (phragmocone~188 mm; maximum shell diameter~320 mm) and the Polish specimen (phragmocone 76 mm; maximum shell diameter 133 mm), it is speculated and the latter be the corresponding microconch.

Active Textile Fabrics from Weaving Liquid Crystalline Elastomer Filaments.

Active fabrics, responding autonomously to environmental changes, are the "Holy Grail" of the development of smart textiles. Liquid crystal elastomers (LCEs) promise to be the base materials for large-stroke reversible actuation. The mechanical behavior of LCEs matches almost exactly the human muscle. Yet, it has not beenpossible to produce filaments from LCEs that will be suitable for standard textile production methods, such as weaving. Based on the recent development of LCE fibers, here, the crafting of active fabrics incorporating LCE yarn, woven on a standard loom, giving control over the weave density and structure, is presented. Two types of LCE yarns (soft and stiff) and their incorporation into several weaving patterns are tested, and the "champions" identified: the twill pattern with stiffer LCE yarn that shows the greatest blocking force of 1-2Ncm-1 , and the weft rib pattern with over 10% reversible actuation strain on repeated heating cycles. Reversible 3D shape changes of active fabric utilize the circular weaving patterns that lead to cone shapes upon heating. The seamless combination of active LCE yarns into the rich portfolio of existing passive yarns can be transformative in creating new stimuli-responsive actuating textiles.