Rib Shape Research Articles

Математический расчет и значение коэффициента восстановления формы грудной клетки при планировании торакопластики врожденной воронкообразной деформации грудной клетки

Актуальность. Врожденная воронкообразная деформация грудной клетки характеризуется разным по глубине и ширине западением грудины и передних отделов ребер. Формообразование, его прогнозирование, расчет деформированного состояния грудной клетки и их изучение при планировании торакопластики по D. Nuss по поводу этой патологии является важной проблемой ортопедии и торакальной хирургии. Цель работы — расчет коэффициента восстановления формы грудной клетки путем соотношения глубины воронкообразной деформации и размера грудной клетки во фронтальной плоскости до и после математического моделирования торакопластики по D. Nuss. Материалы и методы. Для оценки перемещений ребер в зависимости от глубины деформации грудной клетки h были построены две модели. Первая модель представляет собой плоскую раму на опорах, элементы которой состоят из хрящевых частей ребер и грудины. Для данной модели определялась зависимость усилия F, которое необходимо для исправления глубины деформации грудной клетки. Вторая модель представляет собой изогнутый стержень, моделирующий ребро, к одному из концов которого приложена опорная нагрузка, вычисленная при анализе первой модели. Для данной модели определялось перемещение точки фиксации пластины под действием заданного усилия. Для получения более точных результатов были проведены исследования методом конечных элементов на модели грудной клетки. Результаты. Моделировалась коррекция глубины воронкообразной деформации без фиксации пластины к ребрам. Была проведена оценка перемещений участков ребер в месте фиксации пластины при разной глубине воронкообразной деформации грудной клетки: h = 2–5 см. Анализ результатов расчета показал, что после коррекции глубины деформации грудной клетки происходит уменьшение ее размера во фронтальной плоскости. Так, при максимальной глубине деформации h = 5 см отклонение участков ребер в месте фиксации пластины произошло на 2,4 см. Выводы. Установлена зависимость между глубиной воронкообразной деформации и размером грудной клетки во фронтальной плоскости при моделировании новообразованной формы грудной клетки при торакопластике по D. Nuss. Математически рассчитан коэффициент восстановления формы грудной клетки, который составляет 2 (2∆=h), где h — глубина воронкообразной деформации. Практическое значение коэффициента заключается в том, что при планировании торакопластики и придании формы пластине расстояние между ее латеральными концами, которые соответствуют форме грудной клетки и прилегают к ребрам, перед коррекцией воронкообразной деформации необходимо уменьшить на 1/2 h, где h — глубина воронкообразной деформации, для полноценного прилегания к ребрам в послеоперационном периоде.

Effect of Rib Shape on Flow Regime and Heat Transfer

In current study, flow behavior and heat transfer properties in a square channel roughened with square, right triangle, isosceles triangle and circular ribs were examined. The validation test was performed for an experimental square rib case with a pitch ratio (P/e) of 9 and a blockage ratio (e/H) of 0.1. Only to examine the rib shape factor; height, base width, and rib spacing were taken the same in all cases. The study investigated the effect of various rib shapes on flow characteristics, overall thermal performances, normalized heat transfer distributions, and friction factors (pressure losses) at Reynolds numbers of 30,000 and 60,000. As a result of the numerical study, it was found that the rib shape effect did not cause as big differences in the flow properties as the blockage ratio (rib height) and pitch ratio (rib spacing) effect. In terms of the average Nusselt number enhancement, the right triangular ribbed case performed best, circular ribbed case performed worst, while the isosceles ribbed case performed better than square ribbed case. The isosceles ribbed case and right triangular ribbed case cause higher friction factor and pressure loss, while minimum friction is obtained in circular ribbed case and then in square ribbed case. As a result, in terms of overall thermal performances, right triangular ribbed case provided the best performance, followed by isosceles triangular ribbed case. The circular ribbed case produced less friction than the square ribbed case. The thermal performance of the square ribbed case was slightly higher than that of circular ribbed case.

Experimental Study of Perfobond Rib Shear Connector under Lateral Force

A series of full-scale pushed out tests were performed on the Perfobond rib shear connector. The tests were designed to examine the performance of the Perfobond rib shear connector under different rib hole sizes and shapes, reinforcing bar sizes, rib thicknesses, as well as the presence of lateral forces. It has been revealed from the test results that the rib hole size and reinforcement diameter may not act independently, and the influence of one’s size is actually dependent on the size of the other one. The lateral forces also affect the performance of the shear connector; for example, the capacity of the shear connector would be larger under compression than under tension. The existence of transverse pretension stress accelerated the cracking of concrete, leading to the strength and stiffness of concrete, perforated plate, and reinforcing rebars unable to fully exert their effect. In addition, the constraint effect of transverse stress improved the strength and stiffness of concrete and delayed the concrete cracking, bringing the strength and stiffness of concrete, perforated plate, and reinforcing rebars into full play, and resulting in a significant improvement in the shear capacity of Perfobond rib shear connectors.

Numerical modeling of an innovative arc shape rib based solar air heater

Solar air heating is a solar thermal technology wherein the sun energy is absorbed by an intermediate medium and utilized to heat air. In the present paper, a solar air heater equipped with innovative arc shaped ribs is considered. The heat transfer process in the proposed solar air heater is evaluated numerically for Reynolds numbers between 6000 and 12000. The influences of the rib cross section type, the inter-rib distance, the aspect ratio and the pitch of the ribs on the thermal efficiency of solar air heater are analyzed. Results indicate that firstly, ribs with quadrangular type of cross section exhibit the best coefficient of performance. Moreover, ribs with low pitch (40 mm) and aspect ratio equal to 0.5 show the highest thermal performance. Also, the effect of the distance between the ribs on the thermal efficiency of the considered solar air heater is insignificant. Finally, two correlations are obtained for the average Nusselt number and friction factor based on three dimensionless geometric factors.

Compressive testing and finite element analysis-based confined concrete model for stiffened square FRP-concrete-steel double-skin tubular columns

A new variation of fibre-reinforced polymer (FRP) confined concrete-steel double-skin tubular column (DSTC) shows more promise than its traditional form when steel stiffeners are provided on the inner steel tube. Stiffeners can provide better composite action between individual DSTC components, reduce local buckling, and potentially improve confined concrete behavior. The present study performs the first-ever experimental and analytical investigation to quantify the influence of stiffened steel tube on the confined concrete behavior of square-shaped DSTCs. First, a total of 18 DSTC specimens were tested by varying the steel stiffener properties, such as quantity, configuration for the similar total stiffener-rib area, effective placement, and rib cross-section dimensions and shape. Providing stiffened steel tubes in DSTCs showed a significant increase in axial load capacity (up to about 52% in this study) with enhanced ductility than unstiffened specimens. Then the test results were used to propose an analysis-based confined concrete model for square-shaped stiffened DSTCs. Detailed finite element analyses were performed for validation study using the proposed concrete model. The numerical results showed excellent agreement with tests (about 2–4% average errors at critical elastic, peak and ultimate axial loads) and captured well both the elastic and inelastic compressive behavior of stiffened DSTCs. Finally, this study proposed a simple analytical equation for accurately estimating the peak axial load-bearing capacity of square-shaped stiffened DSTCs.

Large-Eddy Simulation Investigation of Modified Rib Shapes on Heat Transfer in a Ribbed Duct

Abstract Internal cooling of the gas turbine blade is critical for the durability of the blade material. One of the ways to accomplish this is by passing coolant through serpentine passages roughened with surface elements to enhance the heat transfer. In the present study, the traditional square rib (SQ-rib) placed normal to the flow direction is modified to a backward-facing step rib (BS-rib) and a forward-facing step rib (FS-rib). Large-eddy simulation (LES) is carried out for a square duct at Reb = 20000. Results show that the modified rib shapes result in substantial increase in heat transfer over the square rib with only a marginal increase in flow losses. The BS-rib shape produces the highest heat transfer augmentation followed by the FS-rib. The overall heat transfer augmentation for the BS-rib and FS-rib is 18% and 10% larger than the SQ-rib, respectively. Thermal-hydraulic performance is enhanced by 15%.

Thermal performance characteristics of a micro-combustor with swirl rib fueled with premixed hydrogen/air

Outer wall temperature and exergy efficiency of micro-combustor are very essential in determining micro-thermophotovoltaic energy conversion effectiveness. In this study, a swirl rib was designed to improve the thermal efficiency of micro-combustor since a swirl flow can be formed when the hydrogen/air mixture passes through the swirl rib, which increases the residence time and turbulence intensity of the mixture. Effects of position, height, spacing, and shape of the swirl rib on the thermal performance of a cylindrical micro-combustor were investigated numerically. The thermal performance shows different trends with the variation of these geometric parameters, and an optimum mean outer wall temperature of 1260 K is obtained at the distance between the inlet and the rib of 7 mm, the rib height of 1.2 mm and the rib spacing of 0.5 mm, but this optimum setting triggers the large pressure drop that impedes further improvement of the micro-combustor performance. To minimize this effect, three rip shapes including rectangle, trapezoid and inversed trapezoid was designed. The results show that the micro-combustor with trapezoidal rib presents better thermal performance. This study provides theoretical guidance for the optimal design of the hydrogen-fueled micro-combustor.

NOx emission and energy conversion efficiency studies on ammonia-powered micro-combustor with ring-shaped ribs in fuel-rich combustion

Ammonia, as an alternative option of conventional hydrocarbon energy source, can achieve carbon free emission. However, the production of NOx is responsible for photochemical pollution and human health. In order to reduce NOx emission at the premise of guaranteeing energy conversion efficiency, three micro-combustors with different ring-shaped ribs in a cross-sectional view of 1) rectangular, 2) Ո-shaped and 3) Ս-shaped are proposed and fuelled by NH3. Extensive numerical comparisons are made with 3D models built by structured mesh. The effects of 1) inlet velocity, 2) equivalence ratio, 3) rib shape and 4) key parameters of these ribs are evaluated. In addition, the normalized sensitivity of NO formation and related reaction pathways are analyzed. It is found that the double-rib structure is more conducive to achieving better thermal performance. Besides, HNO is found to contribute the most of NO, while NH and NH2 are beneficial to the consumption of NO. When the dimensionless distance x between the rib and the combustor inlet is 3/9, comparing the condition of Φ being 1.1 and 1.0, NO emission is reduced by 47.0%, while the radiation efficiency is only decreased by 1.76%. This work has proven that a high energy conversion efficiency and a low NO emission can be achieved at the same time by properly optimizing the internal structure of the combustor in fuel-rich condition.

Computational study of rib shape and configuration for heat transfer and fluid flow characteristics of microchannel heat sinks with fan-shaped cavities

Cavities and ribs are usually utilized in the design of microchannel heat sink systems, and their combination may lead to the optimum overall performance. However, it remains unclear how different combination methods contribute to the performance and efficiency of the systems. Computational fluid dynamics simulations were conducted to identify the optimum rib shape and configuration for the systems with fan-shaped cavities. The ribs are rectangular, diamond, hexagonal, or elliptic in cross-section. The effects of rib shape, dimensions, and configuration are investigated, and the optimum comprehensive performance was determined. The results indicated that the shape, dimensions, and configuration of ribs are important factors that affect performance and heat transfer efficiency. The shape and position of ribs must be optimized to minimize pressure drop while maximizing heat removal efficiency. The shape of ribs can be an important factor in obtaining high efficiency of heat removal while limiting the pressure drop across the channels. When the ribs are rectangular in shape, the maximum pressure drop occurs but the maximum relative Nusselt number is achieved. The maximum comprehensive performance factor is achieved when the ribs are elliptic in shape and the Reynolds number is highest. Further improvement in performance can be achieved by choosing particular rib dimensions and configuration. In order to provide appropriate benefit to such a microchannel heat sink system without inducing additional pressure drop that reduces the performance of the system, it is desirable to properly shape and position the ribs relative to the cooling flow and the cavities in a way that takes best advantage of the benefits provided by the combination of cavities and ribs. The effect of trailing edge vortexes on heat transfer performance is significant. A maximum comprehensive performance factor of 1.96 is achieved when the Reynolds number of the laminar flow is 460.

Analysis of thermo-hydraulic and entropy generation characteristics for flow through ribbed-wavy channel

PurposeThe purpose of this study is to analyze the thermal, hydraulic and entropy generation characteristics for laminar flow of water through a ribbed-wavy channel with the top wall as wavy and bottom wall as flat with ribs of three different geometries, namely, triangular, rectangular and semi-circular.Design/methodology/approachThe finite element method-based numerical solver has been adopted to solve the governing transport equations.FindingsA critical value of Reynolds number (Recri) is found beyond which, the average Nusselt number for the wavy or ribbed-wavy channel is more than that for a parallel plate channel and the value of Recri decreases with the increase in a number of ribs and for any given number of ribs, it is minimum for rectangular ribs. The performance factor (PF) sharply decreases with Reynolds number (Re) up to Re = 50 for all types of ribbed-wavy channels. For Re > 50, the change in PF with Re is gradual and decreases for all the ribbed cases and for the sinusoidal channel, it increases beyond Re = 100. The magnitude of PF strongly depends on the shape and number of ribs and Re. The relative magnitude of total entropy generation for different ribbed channels varies with Re and the number of ribs.Practical implicationsThe findings of the present study are useful to design the economic heat exchanging devices.Originality/valueThe effects of shape and the number of ribs on the heat transfer performance and entropy generation have been investigated for the first time for the laminar flow regime. Also, the effects of shape and number of ribs on the flow and temperature fields and entropy generation have been investigated in detail.

Morphological variability of Oswaldocruzia filiformis (Nematoda: Molineidae) in amphibians from European Russia

The morphological and morphometric variability of the nematode Oswaldocruzia filiformis from ten amphibian species (Pelophylax ridibundus, Pelophylax lessonae, Pelophylax esculentus, Rana arvalis, Rana temporaria, Bufo bufo, Bufotes viridis, Pelobates vespertinus, Bombina bombina and Lissotriton vulgaris) was studied. The sampling was performed during the period of 2018–2020 in fifteen localities of European Russia. We examined the following morphological features: the number of crests in mid-body level, the shape of lateral alae, the shape of cephalic vesicle, shape and structure of spicules in males, the shape and structure of male caudal bursa, the shape and structure of the dorsal ray of bursa; and the measurements of nine morphometric characteristics in nematode females and seven characters in males, subjected to variability. Significant differences in the variability of morphometric characteristics of O. filiformis of both sexes in different amphibian species and amphibians from various regions were revealed. Likewise, significant differences were revealed for most of morphometric features of O. filiformis from amphibians of the same species from different regions of Russia. The type of male caudal bursa and the structure and shape of spicules were identical in all O. filiformis males studied. Likewise, we have not found variability in the structure of the reproductive system in O. filiformis females. Variability was noted in the shape and size of the cephalic vesicle and lateral alae, in the number at the mid-body level, in the shape and structure of the dorsal rib of male caudal bursa. Differences in morphometric characteristics of O. filiformis from amphibians of the same species from different regions of Russia can be explained by the phenotypic plasticity of the species. While variations in the nematode morphology from different amphibian species are caused by the host-induced morphological variability of the parasite. Differences in the size of nematodes and their morphology in different regions of Russia studied may be caused by changes in ecological conditions in amphibian habitats. The broad morphological variability of the nematode O. filiformis increases the adaptive capabilities of the helminth and allows it to parasitize a wide range of hosts.

The case of 'A Rhino Horn': case report and proposal for modification to the Hetsroni and Kelly classification.

Subspine impingement syndrome by definition involves a prominent antero-inferior iliac spine (AIIS) which can lead to impingement on the femoral neck thereby causing symptoms. We present the case of a 22-year-old semi-professional athlete who presented with a Type III AIIS morphology leading to subspine impingement syndrome and was managed via a mini open anterior approach. Radiological examination revealed a fairly prominent left AIIS resembling the ‘horn of a rhino’ extending to the trochanteric region anteriorly. A mini-anterior surgical approach was utilized for the resection of the ‘rhino horn’ and the rectus femoris was reattached. The patient remained asymptomatic at the one-year follow-up and had resumed weightlifting. Following this case, we propose a new classification of the type III AIIS morphology in view of the clinical presentation. The AIIS type III-Standard represents an extension from the acetabular rim to less than 1 cm (type III-S) and type III-Large, with an extension from the acetabular rim beyond 1 cm (type III-L). The type III-L will further be divided into two groups based on its relation to the ilium, type III-Lr (‘rib shape’) and type III-Lrh (‘rhino horn’).

An experimental investigation on mechanical performances of 3D printed lightweight ABS pipes with different cellular wall thickness

In recent years, cellular structures have attracted great deal of attention of many researchers due to their unique properties like exhibiting high strength at low density and great energy absorption. Also, the applications of cellular structures (or lattice structures) such as wing airfoil, tire, fiber and implant, are mainly used in aerospace, automotive, textile and biomedical industries respectively. In this investigation, the idea of using cellular structures in pipes made of acrylonitrile butadiene styrene (ABS) material was focused on and four different pipe types were designed as honeycomb structure model, straight rib pattern model, hybrid version of the first two models and fully solid model. Subsequently, these models were 3D printed by using FDM method and these lightweight pipes were subjected to compression tests in order to obtain stress-strain curves of these structures. Mechanical properties of lightweight pipes like elasticity modulus, specific modulus, compressive strength, specific compressive strength, absorbed energy and specific absorbed energy were calculated and compared to each other. Moreover, deformation modes were recorded during all compression tests and reported as well. The results showed that pipe models including lattice wall thickness could be preferred for the applications which don’t require too high compressive strength and their specific energy absorption values were notably capable to compete with fully solid pipe structures. In particular, rib shape lattice structure had the highest elongation while the fully solid one possessed worst ductility. Lastly, it is pointed out that 3D printing method provides a great opportunity to have a foresight about production of uncommon parts by prototyping.

Enhancement of heat transfer in SAH with polygonal and trapezoidal shape of the rib using CFD

A numerical investigation was carried out in Solar Air Heater (SAH) by implementing an artificial rough absorber plate for higher thermal performances. A polygonal transfer rib, the forward and backward trapezoidal rough ribs were nominated for simulation analysis using ANSYS, Fluent version 13.0. The Renormalization k-ε model was selected to predict the augmentation of Nusselt number (Nu), friction factor (ƒ) characterization and Thermo Hydraulic Performances (THP) for a proposed rib by varying relative roughness pitch P/e = [3.33–20] and relative roughness height e/D = [0.03–0.09]. Dittus Boelter and Blasius correlation were used for validating the smooth surface of Nu and ƒ besides compared with the rough surface to ascertain augmentation of heat transfer. The investigation reported on the performance of Nu and ƒ of the proposed rib at a Reynolds number ranges from 3800 to 18,000. The result reveals that the polygonal rib shape with relative roughness pitch P/e = 3.33 has produced higher Nu and gradual reduction of ƒ at Reynolds number 18000. It was found that THP has achieved a maximum of 1.89 in P/e = 10 & e/D = 0.06 at Reynolds number 15000 in the backward trapezoidal rib.

Influence of Narrow Rectangular Channel ( AR = 1 : 4 ) on Heat Transfer and Friction for V- and W-Shaped Ribs in Turbine Blade Applications

Effective cooling of blades with a nominal pressure drop is essential for performance augmentation and thermal management of gas turbines. Hence, present work is aimed at determining the heat transfer enhancement and friction for W- and V-shaped ribs inside a rectangular cooling channel having hydraulic diameter ( D h ) of 0.048 m and aspect ratio ( AR ) 1 : 4. Ribs are fixed facing downstream with angle of attack ( α ) 45° on opposite walls. Pitch ( P ) between two successive ribs is 25 mm for both cases. Continuous V- and W-shaped ribs with height to channel hydraulic diameter ratio ( e / D h ) 0.052 and 0.0416 and pitch to height ratio ( P / e ) 10 and 12.5, respectively, have been examined for Reynolds number ( Re ) range 20000-80000. Heat transfer augmentation achieved at Re 80000 is 1.94 and 1.8 times higher than Re 20000 for V- and W-shaped ribs, respectively. Streamwise and spanwise variations in local Nusselt number ratio are highest for V-shaped ribs, which are estimated to be 31% and 12%. For W-shaped ribs, variations are 17.5% and 3.5%. Nusselt number ( Nu ) is highest along span length 0.5 w for V-shaped ribs due to dominance of apex induced secondary flow. For W-shaped ribs, Nusselt number along the span lengths is found to be nearly same view uniformity in secondary flow. Maximum enhancement ( Nu / N u o ) estimated for both the rib shapes is 3.9 at Re 20000. Due to increased rib height, friction losses for V-shaped ribs are higher than W-shaped ribs. Maximum friction loss increment is estimated to be 85% for V-shaped ribs and 42% for W-shaped ribs between Re 20000 and 40000. For both rib shapes, impact of ribs is found to be greatest at Re 40000. Thermohydraulic performance ( THP ) for W-shaped ribs is superior to V-shaped ribs. Best THP achieved for W- and V-shaped ribs are 3.7 and 3.4 at Re 20000.

Performance and exergy analysis of different perforated rib designs of triple tubes heat exchanger employing hybrid nanofluids

In the current investigation, heat, flow characteristics, and exergy analysis of hybrid and single nanoparticles-based water passing through a triple ribbed tube heat exchanger (TRTHE) under several design and operation parameters are studied. A computational fluid dynamics (CFD) modeling is carried out using ANSYS-FLUENT 19 code while the validation criteria are accomplished with experimental data and empirical correlations in the literature. The model technique of 3D re-normalization group (RNG)/k–ϵ with enhanced wall treatment is chosen considering the conjugate heat transfer between the fluids. A user-defined function is utilized to specify the thermophysical properties of nanofluids and water based on the operating fluid temperature. The design and operating nanofluid velocity and temperature of inner, intermediate, and outer tubes are 0.7 m/s at 10 °C, 0.05–0.13 m/s at 70 °C, and 0.05 m/s at 18 °C, respectively. The ribs under consideration are trapezoidal, semi-circular, semi-elliptical, triangular, rectangular, and square-shaped and the tested perforated louver widths are 0.5, 1, 1.5, and 2 mm. Three hybrid combinations of nanomaterials (oxide/oxide, oxide/carbide, oxide/carbon nanotube) by constant volume percent of 50/50% are employed with water as a base fluid under a constant volume concentration of 0.1%. Four different kinds of nanoparticles are chosen as Al2O3, MgO, SiC, and MWCNT in order to perform the present study.The obtained findings manifested that the hybrid nanofluid of Al2O3+MWCNT/H2O achieves a higher heat transfer rate compared with single nanofluids. A lower rib louver width with semi-circular rib geometry and staggered rib arrangement leads to an increase in the Nusselt number and effectiveness of the TRTHE. The use of semi-circular rib shape produces a rise of dimensionless exergy loss rate by about 5.4–21.6% more than other rib shapes.

CFD Simulation of Helium Flow Loop Test Section

A helium flow loop is being assembled at Oak Ridge National Laboratory to analyze heat transfer enhancement for systems such as blanket and divertor components. To efficiently identify optimum geometries for heat transfer enhancement in these applications, simulation work is performed to optimize test section designs that are built and tested in the helium flow loop that operates at 4 MPa and a mass flow rate of 100 g/s. Different ribbed geometries that examine rib shape, rib height, rib orientation, rib spacing, and three-dimensional orientation are modeled and simulated in STAR-CCM+ to compare their ability to remove heat and mitigate pressure drop. Following the simulations, models are selected and manufactured for the helium flow loop tests. Simulations initially focus on a hydrodynamic study to determine the appropriate mesh and physics models and then add a heat flux to analyze the heat transfer abilities of the models. The simulations are run in steady state and use a Reynolds-averaged Navier-Stokes k-ε turbulence model. The helium is modeled as an ideal gas. The simulation explores models of geometries that enhance the heat transfer and decrease pressure drop with an overall goal of increasing fluid collision with the wall. Enhanced geometries are simulated to select appropriate designs for manufacturing, and preliminary experimental results are used to validate the simulations. The factors that are being analyzed in the comparison between the experimental and the simulated results include matching thermocouple temperatures, pressure drop, roughness, and fluid velocity.

Research on Construction Control of Vertical Rotation of Concrete-filled Steel Tubular Basket Arch Bridge

This paper focuses on the theme of bridge construction control, using the finite element analysis and calculation program as the platform, taking a concrete-filled steel tube concrete basket arch bridge as the research object, combining the theoretical foundation of the concrete filled steel tube basket arch bridge, and using finite element software to simulate the rotating structure in three dimensions Simulation, analysis of the force status and longitudinal and lateral changes of the rotating structure at various angles and when closing, and the structural stability analysis of the rotating process. The most unfavorable stress conditions and the most vulnerable to instability conditions are determined. And through simulation, the accuracy of the line shape of the steel pipe arch rib in the vertical rotation process, the accuracy of the arch axis detection and the accuracy of the elevation detection are estimated.

Optimized Design of Structure of High-Bending-Rigidity Circular Tube

Circular tubes are widely used in daily life and manufacture under bending load. The structural parameters of a circular tube, such as its wall thickness, number and shapes of ribs, and supporting flanges, are closely related to the tube’s bending rigidity. In this study, a tube with eight ribs and a flange was optimized, in order to obtain the lowest weight, through comprehensive structural optimization. We obtained the optimal structural parameters of the tube and the influence of the structural parameters on the tube’s weight. The structural parameters of tubes with different numbers of ribs were optimized. The tube with different number of ribs had the same inner diameter, bending load, and length as the tube with eight ribs. We conducted an experiment to verify the structural optimization simulation. Different tube sizes were subsequently optimized. The optimized tube with four trapezoidal ribs and a flange reduced the weight by more than 73% while maintaining the same deformation. The weight of the optimized tube with a flange reached a stable value after four trapezoidal ribs were added. When the number of ribs was two, the weight was the largest. The analysis results were consistent with the numerical results. A new AWATR (appropriate width and thickness of ribs can improve the bending rigidity of the tubes) formula was proposed, which can effectively improve the bending rigidity of tubes. Different shapes of tubes were optimized and compared. The optimized tube with four trapezoidal ribs and a flange was the lightest and easy to manufacture.

Impact of rib shape on heat transfer using LES

Numerical studies of the flow field and heat transfer in a fully developed ribbed channel have been performed using Large Eddy Simulation (LES). Validation of the LES against measurements shows encouraging agreement. An immersed boundary method (IBM) has been implemented and validated for use with LES to solve the challenge of varying complex rigid geometries. Ten different rib shapes are investigated aiming to improve heat transfer performance, i.e., square, perforated, triangular with increasing height in the flow direction, triangular with decreasing height in the flow direction, pentagonal with increasing height in the flow direction, pentagonal with decreasing height in the flow direction, house-shaped, groove-shaped, semicircular and arc. The triangular rib with increasing height in the flow direction, with the largest recirculation bubble, was found to provide the best heat transfer performance (accounting for pressure loss), giving up to 7% greater heat transfer than the basic square profile. Ribs with larger recirculating zones tend to provide better heat transfer performance. Rounded-corners with the shortest recirculation zones deteriorated heat transfer performance. Adding round edges to the triangular_up ribs to fit manufacturing conditions, led to heat transfer performance reduction of 12–16%.