Rib Design Research Articles

Heat Transfer Performance Optimization of Rectangular Channel with Truncated-root Ribs

Cooling designs inside the gas turbine blades of aircraft engines are aimed to solve a problem that has existed since the very beginning of the aerospace industry. Since the working environment of turbine blades is extremely harsh when the temperature can rise to 2000K, which is considered a huge challenge for any materials. Therefore, cooling designs such as rib turbulators have always been researched and optimized for better heat transfer enhancement in the cooling mechanism of turbine blades. In this study, a geometric optimization of the rib turbulators inside a rectangular channel was performed with the aim to maximize heat transfer performance. This study investigated the effect of four rib configurations on the heat transfer efficiency of the channel, which include square, truncated-root, convergent truncated-root, and divergent truncated-root rib. Thereby, a module of coupling Python and OpenFOAM was developed to automatically perform the optimization of truncated-root rib design at Reynolds number of 37,000 with design variables are the upstream and downstream height with Powell optimization method. The aim is to figure out the point where the maximum heat transfer performance of the channel is achieved. The study presented in a specific, productive, and accurate way the factors that directly and indirectly affect the heat transfer performance of the channel, thereby giving the optimal results that the channel has the highest heat transfer performance of the presented designs. The results show that the highest heat transfer performance of the optimized design is 12.45% higher than the standard square ribs case.

A Numerical Modelling Approach to Find the Stability of RIB and Snook in Mechanised Depillaring Panel — A Case Study of Kurja Mine

Depillaring by conventional techniques created many irregular shaped pillars, mainly located at shallow depths in different coalfields of India. Continuous Miner Technology (CMT) has been introduced to extract these coal pillars scientifically with safety and productivity with greater depth. Leaving a proper sized rib or snook is a legal requirement as it decides the efficiency and safety of the pillar. However, CMT of square/rectangular shaped pillars created irregular shaped rib and snook. With the conventional empirical formula it is difficult to estimate the strength of such ribs or snooks. These ribs or snooks should be of sufficient size to protect the adjacent slicing operation and junction as well as they should fail in a controlled manner when machines shift inside the extraction. Field studies of different mines found several factors affecting the design of rib or snook. They are various types of induced stress, geological disturbances, manner of extraction etc. Proper assessment of the performance of different sizes and shapes of ribs and snooks in the field is complex due to the problematic underground mining environment for depillaring. For successful operation of the CMT required to study every depending parameter scientifically. Therefore, a numerical model is conducted to estimate the factor of safety of rib and snook to calculate the rib and snook stability. Results of field and simulation studies are presented and discussed in this paper to determine the rib’s stability in the continuous miner panel to create a safe environment for the men and machines.

Determination and Investigation of Natural Frequency Values of A Composite Cover With Rib Design Added

In this study, a long, thin and flexible carbon fiber reinforced composite cover was designed using the CAD module of Unigraphics NX program. Analysis results for different modes were obtained by applying modal analysis to this design with finite element method in ANSYS environment. The modal analysis process is explained in detail, and basic methods and mathematical equations are mentioned. Analysis results were examined in detail, and bending and torsion conditions were evaluated. Based on the analysis results, in order to improve the stiffness of the composite cover, a rib design was made and added to the initial design. A modal analysis process was carried out for ribbed cover design. As a result of the modal analysis, natural frequency values in different mode parameters were obtained and evaluated. With the addition of ribs to the initial valve design, an improvement of %35.52, % 38.79,% 58.07,% 129.11,% 100.35 and % 106.65 was observed in mode 1, mode 2, mode 3, mode 4, mode 5 and mode 6 values, respectively.

Optimization of the bipolar plate rib structure in proton exchange membrane fuel cells with an analytical method

In order to make proton exchange membrane fuel cell vehicles more marketable, not only should costs be reduced, but service life should also be further increased. Important factors determining the expected service life are the deformation and the stress distribution within the carbon paper gas diffusion layer (GDL), on which the rib structure of the bipolar plates (BPP) has a significant impact. Against this background, a new analytical method is firstly developed to predict the deformation and stress distribution within the GDL, due to compression by the ribs, with high accuracy and low computing resources. Based on the analytical method, a new parabolic rib geometry is then proposed, which can significantly reduce the maximum normal and shear stresses occurring within the GDL, thus reducing the possibility of its mechanical damage. The optimized rib design provides guidance for designing and processing commercial fuel cell BPPs.

Two‐dimensional‐numerical investigation on the influence of first rib distance from the entrance of channel on Nusselt number and pressure drop

AbstractEnhancing the heat transfer coefficient in heat sinks can be achieved by surface modification techniques. Although the addition of ribs increases heat transfer capacity, it also increases pressure drop, lowering the channel's thermohydraulic performance (THP) factor. Rib research began a decade ago, with the majority of studies focusing on new rib designs or factors such as relative roughness pitch, relative roughness height, channel width, and channel height (geometric optimization) to improve THP. The goal of this study is to investigate the influence of the positioning of the first rib from the channel entrance on the Nusselt number, pressure drop, and THP factor with a simple design that could be manufactured easily. Three distinct rib designs are evaluated with rib positioning from the channel entrance, rib thickness, pitch, and Reynolds number as the parameters. It was found that the fluid starts settling up at the ribs as the ribs are moved closer to the channel entry point, thus increasing the pressure drop and reducing the fluid velocity. For the proposed design and dimensions, the Nusselt number increases by 3%–5%, and the pressure drop lowers by 4%–14% when the first rib is placed away from the channel entrance.

Effects of Rib Design on the Unsteady Tip Heat Transfer Amplitude for a Turbine Rotor Blade

Abstract By solving the unsteady Reynolds-averaged Navier–Stokes equations and SST k–ω turbulence model, effects of rib design on the unsteady tip heat transfer amplitude for a turbine rotor blade with different rotating speeds are numerically investigated. The results of turbulence model validation are in good agreement with the experimental data. The grid independence verification is also satisfied. The results indicate that the averaged heat transfer coefficient of ribbed tip is 3.1% lower than that of traditional squealer tip and the amplitude of the heat transfer coefficient at the ribbed blade tip is 31.7% lower than that at the traditional squealer tip at standard speed condition. Low-energy passing wake causes the variation of flow field pressure near the tip clearance, which changes the strength of vortex such as pressure corner vortex, scratching vortex, leading edge vortex, and rib vortex inside the cavity, and thus causes the tip heat transfer coefficient fluctuation. At 85% standard speed, the average heat transfer coefficient amplitude of the ribbed tip is reduced by 35.4%. At 115% standard speed, the average heat transfer coefficient amplitude of the ribbed tip is reduced by 44.5%. Ribbed blade tip is suitable to reduce the heat transfer coefficient in turbine design

Impact Damage Analysis of Fiber Reinforced Plastic Structure with Rib

Fiber reinforced plastic (FRP) is a widely used structural form in engineering. FRP ribs can absorb most of the impact energy to protect the structure from damage. The purpose of this study is to obtain the impact resistance of FRP ribs by test and simulation. Taking glass fiber reinforced plastic (GFRP) oil sump as the object, the damage degree of structure under different impact angles, impact velocity, and impactor masses is compared and analyzed by material test, impact test, and simulation. It can be seen from the test results that the design of surface ribs has a great influence on the energy absorption effect of the shell. The constitutive parameters of the shell material are obtained by testing, and the failure mode of the ribs is analyzed by finite element simulation. The impact effects of flying stones with different incident angles, velocities, kinetic energy, and geometric dimensions on the shell are compared and analyzed. The results show that, at the same impact energy, the impact resistance characteristics change regularly under different working conditions. Under a certain incident angle, the damage effect caused by flying stones in a specific mass range is greater. Beyond a certain incident angle, the damage begins to occur, and the larger the incident angle is, the greater the damage effect is. Combined with the actual situation and road standards, the defense of medium quality flying stones is a major concern in the design of oil pan. The results are helpful for designing reasonable ribs to improve the reliability of FRP structures.

Research on the Rational Design Method of Strength Reinforcement for Thin-Walled Structure Based on Limit Load Analysis

Thin-walled structures subjected to internal or external pressure usually need to be reinforced with ribs. The design of ribs is generally based on experiences in engineering, and the results are often very conservative. In this paper, an approach for the rational design of reinforced ribs on thin-walled structures is proposed based on the limit load analysis method, maximizing the limit load of the reinforced thin-walled structure or minimizing the weight of the reinforced ribs. Firstly, the limit load numerical analysis was conducted to study rib forms at the continuous and discontinuous regions of the structure and find the rational ribs which provide the most effective reinforcement for the structure. Then, using the proposed rib forms, an engine test cabin was re-designed based on the limit load analysis to verify the feasibility and effects of the rib design. The engine test cabin after the redesign of the rib plate can reach 98% of the limit load of the original test cabin while the weight of reinforcing ribs is only 62% of the weight of the original ones, which means that the reinforcement design approach based on the limit load analysis method and the rib forms proposed in this paper is effective and feasible, and can achieve a structural lightweight design.

Exergy-Based Thermo-Hydraulic Performance of Roughened Absorber in Solar Air Heater Duct

This paper presents the thermo-hydraulic performance of small conical ribs on the absorber plate of a solar energy air heater (SAH) using exergy analysis. Application of conical protrusion ribs on the absorber is an attractive solution for enhancing the thermal performance of a SAH. However, these ribs are also responsible for high friction losses and increased fan power consumption caused by the turbulent air flow. To optimize the rib design, it is vital to consider both thermal and hydraulic performance at the same time. The SAH was assessed using an analytic method which predicts the exergy efficiency under operating parameters (e.g., Reynolds number, solar insolation and temperature increase parameter). The following geometric quantities of ribs were evaluated for optimum exergy efficiency: the relative rib height (e/D), which was in the range between 0.200 and 0.044, and the relative rib pitch (p/e), which was in the range between 6 and 12. The combination of a relative rib height of 0.044 and relative rib pitch of 10 exhibits the highest exergy efficiency of 0.0202. The optimization of the rib geometric quantities parameters was performed by considering the temperature increase parameter, aiming to achieve maximum exergy efficiency. The combination of rib parameters e/D = 0.044 and p/e = 10 are noted to yield best performance when operating at a temperature increase parameter above 0.0141 K∙m2/W.

Performance Investigation on Mono-Block-Layer Build Type Solid Oxide Fuel Cells with a Vertical Rib Design

Compared with planar-type solid oxide fuel cells (SOFCs), mono-block-layer build (MOLB)-type SOFCs have additional three-phase boundaries per unit volume, and their performance is severely limited by their longer current path. To resolve this issue, a vertical rib design, which was evaluated using a numerical method, was proposed. Compared with the conventional design, the power density for the vertical rib design increased by 12.32%. This is because the vertical rib design provides another short path for current, which not only reduces the ohmic loss in the cathode, but also decreases the ohmic polarization caused by the contact resistance. However, the vertical rib design hinders the transport of oxygen in the cathode and increases the concentration loss. Therefore, the vertical rib size design is crucial. Based on the influence of the vertical rib width, the vertical rib widths on the cathode and anode sides of 0.7 and 1 mm are recommended for different contact resistances, respectively.

Case Studies on Enhanced Heat Transfer in a Square Duct with Modified V-Shaped Ribs (MVR): A CFD Analysis

This research presents structural improvement of V-shaped ribs for a tested square duct (TSD). The V-shaped ribs, which are inserted at the middle of the TSD (called type A), and the V-shaped ribs, which are placed on the opposite TSD walls (called type B), are modified to increase the structural stabilization. The effects of rib height to duct height, b / H = 0.05 – 0.30 ; V-shaped bar thickness to duct height, a / H = 0.025 and 0.050; and flow directions (V-Upstream and V-Downstream) are considered. The new design of the V-shaped ribs is called “modified V-shaped ribs or MVR.” The present problem is solved by the numerical method (commercial code). The flow and heat transfer features of the TSD are illustrated. The numerical result reveals that the MVR give both flow and heat transfer patterns similarly as the general V-shaped rib. The impinging flows, swirling flows, and disturbing thermal boundary layer, which lead to enhanced heat transfer, are observed. Over the investigated range, the enhanced heat transfer about 18.12 times above the smooth duct with the optimal thermal enhancement factor about 4.16 is detected.

ТЕХНИКО-МОРФОЛОГИЧЕСКИЕ И СТИЛИСТИЧЕСКИЕ ОСОБЕННОСТИ ИЗРАЗЦОВ СИБИРИ КАК ИСТОРИЧЕСКОГО ИСТОЧНИКА

Tiles are ceramic products with a front plate and a vertical framed rib (1 inch or higher) on the back side, intended for architectural or stove lining. They became a completely new phenomenon in Siberia in the 17th–18th centuries. Their distribution is associated with the process of civilizational modernization, which entailed the emergence of new industries, technologies, and specialists. Buildings and stoves with tiled decor have not been preserved in the region, written information is scarce, so the main source for the study of Siberian tiles is archaeological materials. The most representative archaeological collections of tiles are from Tobolsk, Tyumen, Tomsk, Yeniseisk, single fragments of tiles were found in Beryozovo, Kuznetsk, Irkutsk and the village of Kemerova. The technical and morphological characteristics of tiles include: the composition of the dough, the quality of fi ring, the size and shape of the front plate, the method of processing and decorating the face, color, rib design. All types of tiles are represented in Siberia: relief terracotta, glazed green and multi-color, single-color smooth, multi-color painted smooth. Relief polychrome tiles dominate quantitatively. All types of tiles are made of red clay. A fragment of a stamp for imprinting an image on an adobe oven was found in Berezovo. Siberian tiles, influenced by the Moscow tiling school, represented at the same time one of the peripheral variations of the transformation of the metropolitan tradition. In the technical and stylistic features of the Siberian tiles, the influence of the European tradition was also reflected. The spread of tile decor and tile trade in the region is a significant manifestation of the transfer of technologies, intercultural exchange and interaction, a vivid embodiment of the process of development and civilizational transformation of Siberia.

On the effective elastic modulus of the ribbed structure based on Schwarz Primitive triply periodic minimal surface

Recently, Schwarz Primitive triply periodic minimal surfaces (P-TPMS) lattice structure has received more and more attention due to its superior mechanical properties and unique topological configuration. In this paper, the effective elastic parameters and deformation behavior of the primary P-TPMS structure and its ribbed reinforced structure are studied, as well as the law of the influence of the change of relative density on them. An analytical model is developed, which can efficiently and accurately predict the effective uniaxial modulus of the ribbed P-TPMS lattice structure based on the effective uniaxial modulus of the primary P-TPMS lattice and the rib structure. By comparing the calculation results of the primary P-TPMS structure with the ribbed P-TPMS lattice structure utilizing the finite element analysis (FEA), it can be obtained that the vertical ribbed design can effectively improve the effective uniaxial modulus of the primary P-TPMS structure.

Evaluation of porous rib and flow pulsation on microchannel thermal performance using a novel thermal lattice Boltzmann method

In this study, a new thermal lattice Boltzmann model (TLBM) is developed to simulate conjugate heat transfer in a microchannel heat sink (MCHS) with porous ribs and pulsatile flow inlet. The examined parameters include the rib to channel height ratio (Hr*), Strouhal number (St), and Reynolds number (Re), which are varied from 0.25 to 0.75, 0 to 3.2, and 100 to 300, respectively. The proposed TLBM is based on the double distribution function framework and capable of addressing heat transfer in combined fluid and porous media conditions. The simulation data show that the flow pulsation inside MCHS with porous ribs not only improves the bulk mean temperatures but also eliminates the rib recirculation zones at some phases, which promotes both the local and overall heat transfer. For fixed Re, the overall Nusselt number (Nu‾/Nu0) and Fanning friction coefficient (f‾/f0) increase and then decrease with increasing St. The maximum values appear at St = 2. For fixed Re and St, the thermal performance factor (TPF) displays a single peak trend with Hr* and the optimal TPF of 2.2 occurs at Hr*=0.5. In addition, compared with the previous ribbed, baffled, and porous MCHSs, the proposed porous rib design under pulsating conditions reports the highest Nu‾/Nu0 of 13.4 in the range of f‾/f0≤200. Finally, the correlations of Nu‾/Nu0 and f‾/f0 with Re, St, and Hr* for the present MCHS are established for the first time, with average differences below 6.7% and 12.4%, respectively.

Investigations of Rake and Rib Structures in Sand Traps to Prevent Sediment Transport in Hydropower Plants

In order to increase the lifespan of hydraulic turbines in hydropower plants, it is necessary to minimize damages caused by sediment erosion. One solution is to reduce the amount of sediments by improving the design of sand trap. In the present work, the effects on sand trap efficiency by installing v-shaped rake structures for flow distribution and rib structures for sediment trapping is investigated numerically using the SAS–SST turbulence model. The v-shaped rake structures are located in the diffuser near the inlet of the sand trap, while the ribs cover a section of the bed in the downstream end. Three-dimensional models of the sand trap in Tonstad hydropower plant are created. The present study showed that integrating rib type structure can reduce the total weight of sediments escaping the sand trap by 24.5%, which leads to an improved sand trap efficiency. Consequently, the head loss in the sand trap is increased by 1.8%. By additionally including the v-shaped rakes, the total weight of sediments escaping the sand trap is instead increased by 48.5%, thus worsening the sand trap efficiency. This increases head loss by 12.7%. The results also show that turbulent flow commencing at the sand trap diffuser prevents the downstream settling of sediments with a diameter of less than one millimeter. The hydraulic representation of the numerical model is validated by comparison with particle image velocimetry measurements of the flow field from scale experiments and ADCP measurements from the prototype. The tested rib design has not previously been installed in a hydropower plant, and can be recommended. The tested v-shaped rakes have been installed in existing hydropower plants, but this practice should be reconsidered.

Numerical and Theoretical Study of Performance and Mechanical Behavior of PEM-FC Using Innovative Channel Geometrical Configurations

Proton exchange membrane fuel cell (PEM-FC) aggregation pressure causes extensive strains in cell segments. The compression of each segment takes place through the cell modeling method. In addition, a very heterogeneous compressive load is produced because of the recurrent channel rib design of the dipole plates, so that while high strains are provided below the rib, the domain continues in its initial uncompressed case under the ducts approximate to it. This leads to significant spatial variations in thermal and electrical connections and contact resistances (both in rib–GDL and membrane–GDL interfaces). Variations in heat, charge, and mass transfer rates within the GDL can affect the performance of the fuel cell (FC) and its lifetime. In this paper, two scenarios are considered to verify the performance and lifetime of the PEM-FC using different innovative channel geometries. The first scenario is conducted by adopting a constant channel height (H = 1 mm) for all the differently shaped channels studied. In contrast, the second scenario is conducted by taking a constant channel cross-sectional area (A = 1 mm2) for all the studied channels. Therefore, a computational fluid dynamics model (CFD) for a PEM fuel cell is formed through the assembly of FC to simulate the pressure variations inside it. The simulation results showed that a triangular cross-section channel provided the uniformity of the pressure distribution, with lower deformations and lower mechanical stresses. The analysis helped gain insights into the physical mechanisms that lead to the FC’s durability and identify important parameters under different conditions. The model shows that it can assume the intracellular pressure configuration toward durability and appearance containing limited experimental data. The results also proved that the better cell voltage occurs in the case of the rectangular channel cross-section, and therefore, higher power from the FC, although its durability is much lower compared to the durability of the triangular channel. The results also showed that the rectangular channel cross-section gave higher cell voltages, and therefore, higher power (0.63 W) from the fuel cell, although its durability is much lower compared to the durability of the triangular channel. Therefore, the triangular channel gives better performance compared to other innovative channels.

Topology optimization on fuel tank rib structures for fuel sloshing suppression based on hybrid fluid–solid SPH simulation

In this paper, we propose a topology optimization method for aircraft fuel tank structural design to reduce the fuel sloshing effect, which is beneficial for aircraft fuel gauge accuracy and flight safety. The method is applied to optimize the hole layouts in the tank rib to reduce fuel sloshing time, increase stiffness, and guarantee lightweight requirements. Specifically, we introduce a hybrid fluid–solid particle based simulator by modeling the impact and elastic forces between fluid (fuel) and solid (ribs, tank wall), to analysis violent fuel sloshing inside the complicated internal tanks, caused by large angle maneuvers and accelerations of an aircraft. Meanwhile, an effective optimizer is built for the rib design, in which the explicitly controlled hole layouts are projected onto the modeled solid particles, such that the process of finite element meshing and remeshing is no longer needed during each optimization iteration. In this way, our proposed method is able to work with complicated aircraft fuel tanks under violent fuel sloshing conditions. We then use a real aircraft wing tank as design case to validate the proposed framework. The result shows that by the generated layout of rib holes, the fuel sloshing time is shortened by 46%, the maximal fuel gauge error is reduced by 14%, and the maximal center of gravity (CG) shift is reduced by 0.15 m.

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.

Numerical study of high temperature proton exchange membrane fuel cell (HT-PEMFC) with a focus on rib design

The rib size is a critical engineering design parameter for high temperature proton exchange membrane fuel cell (HT-PEMFC) stack development, yet it hasn't been studied for HT-PEMFC. A three-dimensional, non-isothermal model was developed in this work to investigate the effect of channel to rib width ratios (CRWR) on the performance of HT-PEMFC. The reaction heat caused by entropy change was divided into cathodic half-reaction heat and anodic half-reaction heat. The results show that the ratio value significantly influence the gas diffusion, electron conduction and the distribution of current density in the porous electrodes. Increasing this ratio facilitates gas transport in the porous electrode but causes higher ohmic loss due to longer distance for electron conduction. As a result, an optimal ratio of about 1 is observed, which results in a peak power density of 0.428 W/cm2. High current density is observed under the channel with a small ratio value while a high ratio value would cause high current density to appear under the rib, signifying the rib size effect on electrochemical behavior of HT-PEMFC. Apart from the electrical power output, the CRWR value also greatly influences the fluid flow and temperature distribution inside the cell, which would influence the long-term stability of HT-PEMFC. In the subsequent studies, efforts will be made to develop new stack configurations with more uniform gas distribution, short electron conduction path and low temperature gradient.

Biologically-inspired rib designs for captured powder damping in additive manufacturing

This paper describes the design and impact testing of laser powder bed fusion 316L stainless steel walls with captured powder cores. The purpose is to determine the effect of biologically-inspired internal ribs on the mode shapes and damping ratios. Comparison is made between five designs: solid and powder core with {no ribs, vertical ribs, hatched ribs, and bat wing ribs}. The powder core increases damping ratios by factors of 2 to 58 depending on the mode number and design. Mode shape and modal parameter evaluations show that the ribbed powder core designs enable tailored dynamics relative to the solid wall.