Helical Ribs Research Articles

Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading

Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading

Technologies to improve wellbore cleaning

Relevance. The main technological process when constructing oil and gas wells is effective wellbore cleaning, especially when drilling horizontal and deviated wells. The article deals with the peculiarities of wellbore drilling technology according to the traditional method in combination with water and hydrocarbon-based polymer-clay solutions, as well as improvement of drilling mud removal properties taking into account density, drilling pump productivity, rheological parameters of the fluid, geometry of the well annulus, shape and concentration of drill cuttings particles. Insufficient cleaning of the well bottom hole causes undesirable phenomena leading to various complications. The object of the research is the technology of cuttings transportation along the wellbore to the surface. The basic formulas characterizing the work of interchangeable hydromonitor nozzles are given. The quality of wellbore cleaning depends on the degree of flow turbulence. Aim. To develop technical solutions that contribute to improving the quality of wellbore cleaning. Methods. Optimal geometrical parameters of hydraulic nozzles for double-deck anti-vibration bit and design of drill pipes with helical ribs have been established by experimental works. Results and conclusions. A double-deck anti-vibration bit with interchangeable hydro-monitor nozzles and drill pipes with helical ribs were developed. Implementation of these developments in the practice of drilling operations will improve the quality of wellbore cleaning by creating a turbulent regime of drilling fluid flow.

Vortex-induced vibration response of the cylinder inspired by Terebridae

Vortex-induced Vibration (VIV) responses of the three-dimensional cylinders inspired by Terebridae are numerically investigated at the Reynolds number ranges of 0.8 × 104 ≤ Re ≤ 8.0 × 104. By Terebridae, we mean that inspired by its slender structural shape, and whether it can be used to improve the VIV suppression performance of the traditional structures. Three different cylinders are considered, including the smooth cylinder (T0), the Terebridae-inspired cylinder with four-start helical ribs (T1), and the Terebridae-inspired cylinder with six-start helical ribs (T2). The VIV responses of T1 and T2 is effectively suppressed, and T1 shows better suppression performance. The results show that the maximum cross-flow amplitude ratio of T1 is reduced by 70.7 % compared with that of T0, and the maximum in-line amplitude ratio of T1 is reduced by 85.7 % compared with that of T0. Compared with the maximum mean-drag coefficient of T0, it is reduced by 44.0 % for T1. In the high Reynolds number ranges, the galloping phenomenon does not occur for T1 and T2, and the relationship between the mean-drag coefficients of T0, T1 and T2 is Cd‾ (T2) > Cd‾ (T1) > Cd‾ (T0). It is found that the changes of Q-criterion vortex structure and wake flow play an important role in the VIV response. The Q-criterion vortex of T0 is a slightly curved linear shaped, and the Q-criterion vortices of T1 and T2 are break up. The three-dimensional geometry of the Terebridae-inspired cylinder undermines the correlation of vortex-shedding along the span. The wake flow of T0 can develop normally. The wake flow of T1 quickly rolls up after passing through the top separation point, and the reattachment of the wake vortex destroys the development of the original wake flow. The continuous development of the boundary layer is destroyed by multiple Terebridae-inspired ribs of T2, resulting in the broken wake. Through the comparison of vortex force, it can be seen that the vortex force of T1 is significantly weakened compared to that of T0, and this also indicates that the three-dimensional geometry of T1 can effectively reduce the intensity of the wake flow.

CFRP Conical Grid Space Structure with Embedded Fiber Optics: Design, Manufacturing and Test

This article discloses the activity developed in the framework of the research project “GRID” aiming at the feasibility demonstration of a fiber optic sensing system (FOS), based on fiber Bragg gratings (FGB), embedded in the ribs of a conical grid structure demonstrator in composite material (CFRP), manufactured by means of dry robotic winding, liquid resin infusion and oven curing. This structure represents an optimized and highly efficient conical adapter for satellite applications that was designed under the same requirements of a conventional CFRP benchmark solution in order to evaluate possible mass savings. Specific interfaces were conceived in order to facilitate the insertion of the fiber optics in the center of helical ribs—pausing the automated deposition phase of the dry preform—and secure them to the structure. Representative grid articles were produced and tested to select the materials and evaluate the preliminary feasibility of the integrated system in conjunction with the infusion process. The proper functioning and use of the sensing system were finally proven during the various phases of the mechanical testing campaign of the demonstrator. Such a campaign included stiffness and strength evaluations and culminated with the catastrophic failure of the structure. The significant amount of data collected from several sensors embedded in the ribs and from conventional sensors glued outside the ribs helped us to better understand the structural behavior and to validate the design and analysis models. The main steps of the design, manufacturing and tests of this project are here addressed.

Composite anisogrid lattice toroidal shell: Application to a load-carrying rim of the spacecraft reflectarray antenna

A novel design of the composite transformable/foldable rim of the spacecraft reflectarray antenna is presented in the paper. The rim is made in the form of anisogrid lattice toroidal shell split into six parts that are jointed using hinges containing helical springs. The springs create the moments required to deploy the antenna in orbit. A dielectric flexible flat membrane with reflective radiating elements generating a radio signal with required directivity is stretched on the rim. An algorithm of the finite-element model generation is developed for the toroidal rim using a typical finite-element unit cell of lattice structure. The lattice toroidal shell is modelled as a three-dimensional frame composed of curvilinear ribs. The results of design analysis of the lattice rim delivering a minimal mass to its structure subject to constraints imposed on the fundamental frequency, values of stress, and the buckling load factor are presented in this work. The corresponding set of design parameters of lattice structure, including the angle of orientation of helical ribs, number of helical ribs of one orientation, and size of the ribs’ cross section are identified based on these results.

Flow field and heat transfer of ferromagnetic nanofluid in presence of magnetic field inside a corrugated tube

The present study investigates the effects of using a magnetic field on the flow field and heat transfer of ferromagnetic Fe3O4/H2O nanofluid considering two-phase model for nanofluid in heat exchanger equipped with helical ribs. Three methods are employed to enhance the thermal efficiency of heat exchanger, as employing of corrugations, utilizing nanofluid as heat transfer fluid, and employing the magnetic field. The performance evaluation criteria index (PEC) is employed to analyze the thermal-hydraulic characteristics of the heat exchanger. The main aim is to achieve an optimum model with the highest performance evaluation criteria value. Usaging of corrugated heat exchanger or nanofluid can increase the average Nusselt number and friction factor in the tube sharply. Also, it is understood that the presence of a magnetic field has a significant effect on the heat transfer enhancement inside the heat ex-changer. The model with magnetic field of 600 G has the highest Nusselt number ratio among all studied models, which is followed with 400 G, 200 G, and 0 magnetic fields, respectively. Furthermore the effects of different corrugation heights, widths, and pitches have been stud-ied. Finally, usage of the novel corrugated heat exchanger with 14 mm corrugation heights, 9 mm rib width, and 12.5 mm blade pitches filled with nanofluid, and under a magnetic field of 600 G it suggested as the most efficient configuration. Also, at the Reynolds number of 4,000, the highest performance evaluation criteria values are achieved.

Experimental investigation of entropy generation in a pipe heat exchanger with turbulence generator inside and on the outside

The thermal performance of a pipe heat exchanger can be improved with the use of turbulator inserts. This is accompanied with a drop in pressure because of secondary swirl flow creation in the exchanger. A number of experiments were performed to find the entropy formation with twisted tape inserts inside a tube and helical ribs over the outside of a tube heat exchanger. A counter flow system with water being used as a working fluid was used. The simple pipe validation was performed using standard correlations, and the findings were found to be within an acceptable range. As the Reynolds number was increased, it was discovered that the irreversibility of heat transfer gets increased. As the twist ratio falls, the entropy created due to friction increased. The Bejan number demonstrates that the formation of entropy is mostly attributable to the irreversibility of heat transport rather than the irreversibility of fluid friction. A Bejan value close to one suggests that there is a significant irreversibility of heat transfer in all instances.

Invoking Pre-Rotation Induced Flow to Improve the Performance of Gas Turbine Film Cooling

The present study proposes a novel method to improve the performance of film cooling. In this type of cooling, due to the presence of counter-rotating vortex pairs downstream of the injection hole, the formed film on the surface tends to detach from the surface. A new geometry is proposed to overcome this vortex pair. In this geometry, the injection passage is equipped with one or more helical ribs. These ribs induce rotation in the injected cooling fluid flow which prevents the separation of the coolant film from the surface. Analysis and optimization of the effective parameters are done including the injection angle, the height, thickness, number, and pitch of the ribs. The results show that by exceeding the injection angle from an optimum value, the mixing tendency of the injected fluid and main flow increases, and the cold fluid film liftoff occurs faster. On the other hand, as this angle decreases, the pressure drop rises. Considering both the heat transfer and pressure drop effects, the best performance is observed at the injection angle of 20°. Moreover, the best performance is achieved for the ribbed passage (of D diameter) with two ribs of 0.025D ​​thickness, 0.1D height, and 0.33D rib pitch.

Rifled microtubes with helical and conductive ribs for endurable sensing device

Helical fibers represent of one of the most extraordinary objects in living organisms and have recently produced through a coaxial microfluidic spinning process. But the requirement of collection capillaries may limit scalable production because of blockage liability, structural rigidity and cumbersome fabrication of capillary. Structural vulnerability of helical fibers could also limit their practical applications, e.g., in fabric and as wearable devices. Herein for the first time we showed that helical fibers could be produced solely with a core steel needle with double concentric sleeves through a coaxial wet spinning process, without the requirement of microfluidic spinning capillary. They were encapsulated into protection microtubes in an unprecedented form of rifled microtubes with helical ribs. The presence of protection microtubes promote not only their mechanical properties, but also structural endurance to various practical circumstances. These rifled microtubes could serve as endurable and sensitive wearable strain/stress sensors (up to ∼300% strain and ∼100 kPa stress) to monitor various human motions, without showing conspicuous performance decay even after >104 cycles of measurements. This study offers not only a facile and scalable pathway of producing helical fibers, but also an unprecedented platform of rifled microtubes as endurable and sensible sensors of strain and pressure.

Turbulent heat transfer in pipes with increased roughness through shavings of helical ribs

Large-eddy simulations of mircrostructured pipes are carried out in this study. The pipes are helically ribbed with several starts from which shavings are cut out along the rib. A Reynolds number of 16,000 and a Prandtl number of 9 are applied. Cyclic boundary conditions are used to simulate an infinitely long pipe and a LES turbulence model is applied. The results show that both the number of starts and the distance of the shavings along the rib, have an impact on turbulence and heat transfer. An optimum was found for the number of starts regarding heat transfer. The heat transfer area increases for a higher number of starts, but the flow-related heat transfer decreases. Thus, an optimal arrangement of starts was identified for this pipe configuration. The variation of the arrangement showed that the pressure loss can be reduced by an inline configuration, whereby the heat transfer is only slightly decreased. It can be shown that the simulations can contribute to optimising complex structures in the future and thus accelerate the development process of new geometries. It can be shown that the development of new heat exchanger pipes is also possible with complex structures, this can be demonstrated here for the first time for structures that can actually be fabricated.

3D scanning and 3D printing to develop internally helically ribbed tubes

We developed 3D scanning and rapid prototyping-based approach for an easier design of high precision, single pass tube drawing technology dedicated to the manufacturing of high-quality internally helically ribbed tubes. The major difficulty in the currently used process design is the identification of floating plug stability criterion allowing manufacturing of high precision helical ribs. The novelty of the proposed approach is therefore to use a combination of 3D scanning and rapid prototyping processes to design a complex floating plug geometry based on minimizing membrane energy. It was combined with computer-aided design of drawing die geometry and process parameters of the optimal tube drawing.

Numerical study on a fractal-like multi-cell tubes with the Fibonacci helical section under axial crushing

A novel bio-inspired fractal-like multi-cell tube (FMT) was developed based on the Fibonacci spiral structure in creatures. A numerical study on FMTs with different sectional configurations was conducted under axial crushing using the nonlinear finite element method. Three criteria used to evaluate the crashworthiness of the FMTs: initial peak crush force ( Fp), specific energy absorption ( Es), and crush force efficiency ( Cf). The effects of different numbers of helical ribs N and wall thickness t on the crashworthiness and deformation mode of the FMTs were analyzed. Secondly, an analytic hierarchy process (AHP) method and a complex proportional assessment (COPRAS) method were applied to select the best possible sectional configuration. According to this method, three types of FMT with one, three, and five ribs (FMT1, FMT3, and FMT5) were determined to have a superior sectional configuration. Finally, a metamodel-based multi-objective optimization method based on a polynomial regression metamodel and multi-objective particle optimization (MOPSO) algorithm were employed to optimize the structural parameters of the FMT1, FMT3 and FMT5 under six designed cases, including two criteria cases and three criteria cases, where t and basic diameter D1 of the Fibonacci helical were considered the design variables. The multi-objective optimization results indicated that the optimal D1 does not exceeding 15 mm, the optimal t ranges from 0.29 to 0.72 mm under three criteria cases. Further research pertaining to the crashworthiness analysis of FMTs under oblique crushing should be conducted.

CCRobot-IV: An Obstacle-Free Split-Type Quad-Ducted Propeller-Driven Bridge Stay Cable-Climbing Robot

This letter presents CCRobot-IV, the fourth version of a climbing robot designed for bridge cable-inspection tasks. CCRobot-IV inherits design features from the previous CCRobot series, and has improved capability for crossing cables with obstacles such as helical ribs, small metal accessories, and various other obstacles. CCRobot-IV consists of a quad-ducted propeller-driven climbing precursor and an affiliated payload-carrying body. Because a quad-ducted propeller does not depend on friction generated by mutual contact and extrusion, the precursor’s locomotion is decoupled from the surface of the bridge cable and the obstacles on it. When the precursor climbs up to reach the set position, it uses its gripper’s self-locking palms to grasp the bridge cable, which creates a fixed anchor point that allows the payload-carrying body to pull itself up using wires and two winches (which are a type of driving wheel that do not require extrusion force on the cable to produce adhesion and friction). Therefore, the robot’s payload capacity is also decoupled from adhesion to the cable surface, and thus the entire system has obstacle-free operation. Experimental tests and field tests have demonstrated CCRobot-IV’s climbing performance, payload capacity, and potential application utility.

Finite-element modelling, analysis and design of anisogrid composite lattice spoke of an umbrella-type deployable reflector of space antenna

Practical design procedure of a new configuration of anisogrid composite lattice spoke of an umbrella-type deployable reflector of space antenna is presented in the paper. The spoke has a form of long lattice shell with the cross-section made in the form of rounded rectangle. The loads applied to the spoke are generated by the radio-reflective stretched mesh of the deployed reflector. Mass of the spoke is taken as an objective function in the formulated design problem, with constraints imposed on the characteristics of deformability, strength, and stability of the structure. The solution of the problem is based on the results of parametric analyses performed using the finite-element method. The set of design parameters of lattice structure includes the angle orientation of helical ribs, number of helical ribs of one orientation, widths of the helical and hoop ribs, and height of the ribs. A specialised algorithm is developed and applied to the generation of finite-element model for the anisogrid lattice spoke with rectangular cross-section. Using this model, the effects of variations of the parameters of lattice structure on the maximum deflection, maximum stresses in the ribs, and buckling load factor are analysed. Based on the results of these analyses the optimum set of the parameters of lattice structure is identified. At the first stage, feasible values of the structural parameters satisfying the set of constraints are calculated. Then, the optimum combination delivering the minimum value of the spoke mass is determined.

Turbulent Heat Transfer in Pipes with Increased Roughness Through Shavings of Helical Ribs

Turbulent Heat Transfer in Pipes with Increased Roughness Through Shavings of Helical Ribs

Experimental Comparative Analysis of Overall Heat Transfer Coefficient in Counter-Flow Heat Exchanger by using Helical Ribs

More performance or reduced the size of heat exchanger can be achieved by heat transfer enhancement technique. Tube helical ribs have been used as one of the passive heat transfer enhancement technique and are most widely used tube in a several heat transfer process. The results of the heat transfer characteristics in horizontal double pipe with helical ribs are presented. Six test section with different characteristics parameters of helical rib depth 1.0mm, 1.25mm, 1.5mm and helical rib pitch 4mm, 6mm, 8mm, are tested. Cold water and hot water are used as the working fluids in the shell side and tube side respectively. Experiments are performed under the condition of mass flow rate varying from 0.030 to 0.130kg/s for cold water and 0.040 to 0.140kg/s for hot water respectively. The inlet cold and hot water temperature are between 28- 300C and between 68-710C respectively. The results obtained from the tubes with helical ribs are compared with those without helical ribs. It is found that the helical ribs have a significant effect on the heat transfer coefficient and the heat transfer increases with the helical rib pitches and depth. Based on fitting the experimental data, on- isothermal correlations of the heat transfer coefficient and friction factor are proposed.

Equivalent continuum method for anisogrid composite lattice conical shells with equiangular, equidistant and geodesic spiral ribs

This paper is concerned with filament winding trajectories of helical ribs of anisogrid composite lattice conical shells. Filament winding can be designed to coincide with equiangular, equidistant and geodesic spiral trajectories. The unified geometrical formulas of the three types of conical spiral and circumferential curves are established. As a consequence, three types of lattice conical shells are built and the corresponding geometric parameters of lattice conical shells are obtained. Additionally, the smearing method, adopting straight-line and curved-line assumptions for helical ribs, respectively, is applied to calculate the elastic properties and the global stiffness properties along with the classical membrane theory. The finite element analysis verifies the analytical results and also shows a closer correspondence with numerical results for the curved-line assumption than the straight-line assumption. Further, the global stiffness properties of three types of lattice conical shells are compared using the single variable method. The results indicate that the flexural stiffness and the torsional stiffness of the lattice conical shell with equiangular helical ribs are the maximum and the axial stiffness of the shell with geodesic helical ribs is the maximum among them, while the values of all stiffness properties of the shell with equidistant helical ribs are the minimum among them.

Numerical Investigation of Hydraulic-Thermal Performance for a Double-Pipe Heat Exchanger Equipped with 45°-Helical Ribs

In this paper, the hydraulic-thermal performance of a double-pipe heat exchanger equipped with 45°-helical ribs is numerically studied. The ribbed double-pipe heat exchanger is modelled using three heights (H = 0, 2.5, 3.75, 5 mm) of 45°-helical ribs. Two numbers (4-ribs and 8-ribs) of 45°-helical ribs are attached on the outer surface of the inner pipe of the counter-flow double-pipe heat exchanger and compared with a smooth double-pipe heat exchanger. Three-Dimensional computational fluid dynamics (CFD) model for a laminar forced annular flow is performed in order to study the characteristics of pressure drop and convective heat transfer. In addition, the influence of rib geometries and hydraulic flow behaviour on the thermal performance is system-atically considered in the evaluations. The annular cold flow is investigated with the range of Reynolds numbers from 100 to 1000, with three heights of ribs at the same width (W = 2 mm) and inclined angles of (θ = 45°).The results illustrate that the average Nusselt number and pressure drop increase with an in-creasing number of ribs, the height of ribs and Reynold number, while the friction factor decreas-es with increasing Reynolds numbers. The percentage of averaged Nusselt number enhancement for three rib heights (H = 2.5, 3.75 and 5 mm) at 4-ribs is (34%, 65% and 71%), respectively, While for 8-ribs the enhancement percentage is (48%, 87% and 133%) as compared with the smooth double-pipe heat exchanger at Re = 100. The best performance evaluation criteria of (PEC) at (8-ribs, and H = 5 mm) is 2.8 at Re = 750. The attached 45-helical ribs in the annulus path can generate kind of secondary flows, which enhance the fluid mixing operation between the hot surface of the annular gap and the cold fluid in the mid of the annulus, which lead to a high-temperature distribution. Increasing the height of 45°-helical ribs lead to an increase in the sur-face area subjecting to convective heat transfer.

A strategy of parallel winding of circumferential ribs and helical ribs for composite cylindrical grid structures

The advanced grid structure is a typical fiber reinforced polymer composite structure with high specific stiffness and high specific strength which has a broad prospect of application in the aerospace field. However, the current manufacturing process inevitably introduces wrinkles and voids at the intersection, which results in decreased performance of the grid structure. In this paper, the effect of winding patterns on the structure at grid intersections is studied.The mathematical model for steering fibers at intersections and the parallel winding strategy of circumferential and helical ribs in a cylindrical grid structure are both developed.These models show that fiber bridges and buildup always exist at intersections where fibers are steered. The fiber morphologies at the intersections of the grid structures formed by different fiber paths are compared. And finite element models are developed to analyze the effect of different paths on the strength of the structures at the intersection. A cylinder grid structure is manufactured, and a uniaxial compression test is carried out to evaluate it compressive performance.

Numerical study on the nanofluid flows and temperature behaviors in the spirally coiled tubes with helical ribs

The nanofluids heat transfer and flow behaviors in the spirally coiled tube with and without helical ribs are simulated using the Eulerian two-phase turbulent model. A model used in the present study is 8.5 mm diameter copper tube, bending into the spirally coiled tube with and without helical ribs under constant wall temperature conditions. As flowing in the spirally coiled tube, the secondary flow is induced by the centrifugal force. In contrast, the swirling flow is caused by the pipe's helical ribs, which have significant effects on the Brownian motion of nanoparticles suspending the base fluid and then results in higher heat transfer enhancement. It can be found that the helical rib configurations have a significant effect on the velocity and temperature contours. The Nusselt number from the spirally coiled tube with helical ribs is 12.45% higher than those without helical ribs. However, due to more flow complexity and roughness augmentation, the pressure drop across the test section also increases. Besides, adding 0.05% nanoparticles by volume to water enhances the Nusselt number by 8.21%—also, the overall enhancement in heat transfer.