Fin Shape Research Articles

Flapping Soft Fin Deformation Modeling using Planar Laser-Induced Fluorescence Imaging.

Propulsive mechanisms inspired by the fins of various fish species have been increasingly researched, given their potential for improved maneuvering and stealth capabilities in unmanned vehicle systems. Soft materials used in the membranes of these fin mechanisms have proven effective at increasing thrust and efficiency compared with more rigid structures, but it is essential to measure and model the deformations in these soft membranes accurately. This study presents a workflow for characterizing the time-dependent shape deformation of flexible underwater flapping fins using planar laser-induced fluorescence (PLIF). Pigmented polydimethylsiloxane fin membranes with varying stiffnesses (0.38 MPa and 0.82 MPa) are fabricated and mounted to an assembly for actuation in two degrees of freedom: pitch and roll. PLIF images are acquired across a range of spanwise planes, processed to obtain fin deformation profiles, and combined to reconstruct time-varying 3D deformed fin shapes. The data are then used to provide high-fidelity validation for fluid-structure interaction simulations and improve the understanding of the performance of these complex propulsion systems.

Numerical investigation on the performance and environmental aspect of roll bond photovoltaic thermal unit condenser incorporating fins on the absorber

To contribute to the sustainable energy production, the current paper proposed and numerically solved a model of roll bond photovoltaic thermal (RB-PVT) condenser with fins by using ANSYS Sotfware18. First, the effect of four different fin shapes and number was analyzed to determine the fin shape and number best suit for the study. Last, on the basis of RB-PVT unit condenser with 3 fins of straight rectangular shape, a sensitivity was conducted considering fin length and width in the range of 0.2–0.7 mm, and 195⁰-255⁰ and 345⁰-285⁰ for the position of fin on left and right side of the fixed one, respectively. The highest average values in heat dissipation flux, pressure drop and overall fin efficiency were respectively obtained to be 1792.693 W/m2, 86.471 kPa and 79.767% when varying fin(s) width and angle. In addition, the average refrigeration coefficient of performance (COP) of 5.079 and which is higher than that of previous studies was achieved. Meanwhile, the maximum average of 258.07 united state dollars (USD) would be saved to capture and store 8.603 tons of emissions (CO2), after every 5 years. RB-PVT unit with fins not only can improve the system performance but also can help achieving a clean environment.

Three-dimensional shape optimization of fins in a printed circuit recuperator using S-CO2 as the heat-transfer fluid

Printed circuit heat exchangers (PCHEs) are among the most promising candidates for recuperators in the S-CO2 Brayton cycle owing to their high-pressure resistance and high compactness, where the fins are usually installed in channels to improve the thermal-hydraulic performance. The fin shape optimizations have been performed in several previous studies for enhancing the heat transfer and reducing the pressure drop. However, most of them are limited to two-dimensional optimization where the shape variation along the height direction was ignored. In the present study, three-dimensional fin shape optimizations are performed for the PCHE recuperators using S-CO2 as heat transfer fluid to further improve the thermal-hydraulic performance. The heat transfer and pressure drop characteristics in channels with optimized fins are comprehensively evaluated by comparing against conventional cylindrical fins and airfoil fins. The results indicate that the optimized three-dimensional fins feature variable cross-sections along the height direction. Such three-dimensional fins can significantly diminish the impact area of fluid, which is conducive to reducing the local flow resistance caused by high-velocity gradient and consequently improving the comprehensive heat transfer performance. Under the typical working condition studied in this paper, the heat transfer capacity in hot channels of recuperators with the optimized three-dimensional fins is 21.2% greater than the cylindrical fins, and 17.3% greater than the airfoil fins when the identical pressure drop is fixed; while the heat transfer capacity in cold channels with the optimized three-dimensional fins is 24.3% greater than the cylindrical fins, and 29.3% greater than the airfoil fins. In addition, the robustness analysis indicates that the optimized three-dimensional fins can yield more excellent thermal-hydraulic performance than conventional cylindrical fins and airfoil fins over a wide range of working conditions.

A novel age-group classification method for Irrawaddy dolphins based on dorsal fin shape features

The Irrawaddy dolphin is an endangered marine mammal species; therefore, there is an urgent need to take protective measures, especially in terms of population breeding and evolution. To address this, it is important to understand the age group structure of populations. Unlike biological individual identification and biological object detection based on pattern classification methods, a new age-group classification (AGC) method was developed to classify Irrawaddy dolphins into three age groups: older, middle-aged, and juvenile. Taking into account the relation between the dorsal fin shape features of Irrawaddy dolphins and their age, the AGC method constructed several dorsal fin geometric morphological features, such as leading edge length and dorsal fin height, using edge extraction and curve fitting of dolphin images. After performing a multicollinearity test on these features, nine effective features were obtained. A model was then trained to classify Irrawaddy dolphins according to their age groups. The experimental results demonstrated that the AGC method has a high classification accuracy of 80.20% for older dolphins. In contrast to individual identification and object detection methods, the proposed AGC method facilitates the analysis of population structure stability and dynamics by classifying Irrawaddy dolphins by age.

A Review on Peltier Device and Heat Dissipation of It’s Hot Surface Using Fins

Abstract: The branch of thermal science is widely involved in refrigeration theory used at many places like Air Conditioners, Air Cooler, Refrigerator, etc. Refrigeration cycles and their concept were newly introduced in early 1834 and after that in 1913 refrigerators for possible to use for home applications and at various places. When it comes to cooling mainly the refrigeration process comes in mind for the solution, But Peltier effect which is reverse of seebeck effect is also well known for cooling as portable cooling in compact size is possible by TEC Module as Peltier devices generates heating at one side and cooling at other side when there is a voltage difference between two dissimilar metals. TEC Module of various ampere gives various ranges of temperature at different voltages and current. Different models of TEC Module (Peltier device) are mainly varied in terms of current as no. of P-N junctions remains same as voltage and current can be modified. The heat generated in at one side of Peltier device is extremely high and if that heat is not dissipating then TEC module will be damaged and won’t be possible to bring back in working conditions. So, in Heat Transfer the theory of extended surface is mainly important for heat dissipation. So different geometry of fins is being used such as rectangular fins, Annular fins, Trapezoidal fins, Inversely Trapezoidal fins, etc. The shape and thickness of fins are the most important factors affects heat dissipation. Another thing needed to be taken in account is analysis on material composition of fins which is affected by the term thermal conductivity of the materials. Keywords: Peltier Device, Thermoelectric Module, Heat Dissipation, Fins, Peltier Effect, Refrigeration, Heating, Portable cooling, and heating.

Topology optimization of an airfoil fin microchannel heat exchanger using artificial intelligence

High-performance microchannel heat exchangers are needed to supply heat for power conversion for nuclear microreactors. An airfoil fin microchannel design, constructed of Alloy 617 with helium as the working fluid, is analyzed and optimized using a design of experiments with artificial intelligence techniques. The use of airfoil fins offers the potential to reduce pressure drop across the heat exchanger, as compared to other types of channel configurations. A framework for topology optimization of airfoil fin printed circuit heat exchangers (PCHEs) has been developed that can be readily extended to different fin sizes and shapes, as well as different inlet and operating conditions, materials of construction, and working fluids. An optimization procedure is developed that employs computational fluid dynamics for a set of design points identified using Latin hypercube sampling. Computational fluid dynamics is used to analyze a simplified two-channel configuration where five design parameters are varied – inlet angle, fin scale, extent of staggering, transverse and longitudinal pitches. Two methods (a 5D polynomial and a regression neural network) are compared for generating surrogate models and the resulting response surface approximation is input to a genetic algorithm that is used to identify a set of optimal parameters. The optimal geometries are found across six channel Reynolds numbers ranging from 1000 to 5000, since inlet conditions affect flow through the heat exchanger. A set of optimal designs that maximizes heat transfer and minimizes pressure drop is identified, and a thermal stress analysis is performed on the optimal design. Correlations for the Nusselt number and Darcy friction factor are developed that can be useful for thermal hydraulic analyses using system codes. Thermal stresses are analyzed and a brief discussion of the status of code cases of PCHEs for nuclear applications is given. Testing and thermomechanical modeling is needed to facilitate future code compliance of PCHEs for high pressure and high temperature applications.

Genomic consequences of domestication of the Siamese fighting fish.

Siamese fighting (betta) fish are among the most popular and morphologically diverse pet fish, but the genetic bases of their domestication and phenotypic diversification are largely unknown. We assembled de novo the genome of a wild Betta splendens and whole-genome sequenced 98 individuals across five closely related species. We find evidence of bidirectional hybridization between domesticated ornamental betta and other wild Betta species. We discover dmrt1 as the main sex determination gene in ornamental betta and that it has lower penetrance in wild B. splendens. Furthermore, we find genes with signatures of recent, strong selection that have large effects on color in specific parts of the body or on the shape of individual fins and that most are unlinked. Our results demonstrate how simple genetic architectures paired with anatomical modularity can lead to vast phenotypic diversity generated during animal domestication and launch betta as a powerful new system for evolutionary genetics.

Emergence of asymmetric straight and branched fins in horizontally oriented latent heat thermal energy storage units

Mobilized thermal energy storage units have a vital role in reducing energy consumption in buildings by enabling industrial waste heat to be used in buildings. High conductive fins can enhance the heat transfer performance of mobilized thermal energy storage tanks which suffer significantly from the low thermal conductivity of phase change materials. On the other hand, investment costs of the mobilized thermal energy storage tanks need to be decreased to compete with fossil fuel-driven systems in buildings. The present study numerically investigates the effect of innovative fin structures on the melting performance for fixed fin material volume to disable cost increase. Two-dimensional models with phase change were simulated for shell-and-tube heat exchangers. The shell geometry was designed sufficiently large to observe the melting growth of phase change material independent from shell walls within the given charging time. Straight and Branched type fin structures with the fin numbers of Nfin=2, 4, and 6 were simulated to uncover the effect of shape and length scale of fins on natural convection-driven melting. It was found that Straight fin type is more suited than Branched fins as they do not show significant melting enhancement with increased complexity and cost. The fin structures in all cases performed better when located at the top of the heat transfer fluid tube, even though the literature considers that top-located fins inhibit natural convection circulations. Varying the number of fins from (2-fin) to (4-fin) causes 15.8% increase in melting ratio, but further increase in the fin number (6-fin) reduces melting ratio below the (4-fin) case. Within (4-fin) structures located at the top, using distinct fin lengths yields melting ratio to increase 28.1%. Overall, the results show that heat transfer could be improved by varying the fin structure without increasing total fin volume and cost. The melting region growth shape with optimized fin structure forms the basis for the multitube arrangement of mobilized thermal energy storage units to enhance heat transfer performance with low cost.

Hydrodynamic effects of the caudal fin shape of fish in carangiform undulatory swimming

As an important structure for generating thrust, the shapes of fish tails have adaptively evolved to achieve great swimming performance through natural selection over hundreds of millions of years. The particular optimal tail shape of fish is not universal for all situations but significantly varies with other factors, such as undulatory kinematics. In this study, using a sharp-interface immersed boundary method with a self-propelled model, we investigated the hydrodynamic performance of swimmers that equipped with three different caudal fins in a common undulatory mode, carangiform locomotion, to determine the optimal shape. The three caudal fins tested are as follows: a round fin emulating that of snakehead fish ( channidae), an indented fin emulating that of saithe ( Pollachius virens), and a lunate fin emulating that of tuna ( Thunnus thynnus). At the regular undulating amplitude A = 0.1 L at the tail tip (L is the body length), the swimmer with the indented tail achieves the highest speed U = 1.45 L/s with a relatively high quasi-propulsive efficiency of η q = 0.324; at a higher undulating amplitude A = 0.15 L, the indented tail swimmer achieves slightly lower speed than the lunate fin swimmer, who has the highest speed (2.06 L/s vs. 2.07 L/s), but the efficiency of the former is higher than that of the latter. Therefore, the indented fin is believed to perform the best among the three fins tested regarding carangiform undulatory swimming. This finding is consistent with observations made on fish in nature, for example, carangiform swimming fish that have been evolving for hundreds of millions of years have a caudal fin similar to the indented caudal fin in the current study.

Optimization of Fin with Rectangular and Triangular Shapes by Levenberg – Marquardt Method

The article proposes using the Levenberg – Marquardt (L – M) method to optimize the fin with the longitudinal profile. The objective in optimizing the fin shape: The fin volume achieved the minimum value, with the optimization variables being the fin's width and length. The research performed two problems about optimal design the fin with the straight profile for triangular and rectangular shapes, obtained a tiny relative error compared to the results of the published studies. Specifically, the problem with the triangular-shaped fin, the relative error of the minimum volume compared to the two published is 0.022% & 0.092%; and the problem with the rectangular-shaped fin, the relative error is 0.68% & approximately 0%, respectively.

Thermal and Flow Analysis of Different Shaped Pin Fins for Improved Heat Transfer Rate

In this paper, a micro pin fin heat sink is numerically investigated with four fins geometries (circular, elliptical, square, and drop shape) at two types of arrangement styles, inline and staggered arrangement. The hydrodynamic and thermal characteristics of different fin geometries and two arrangement styles have been compared under the exact value of Reynolds number and constant wall temperature thermal boundary conditions. The Reynolds number was sweeping in the range of (400-2800) to ensure the fluid flow velocity impact in the pin fin performance. The results obtained indicate that a longitude pin fin dropped with increasing Reynolds number at a distributed temperature. Also, the circler Pin fin reaches the lowest temperature comparison to the rest of the three-pin fin types. Generally, according to the extracted, Nusselt number for different geometries increased versus increasing the Reynolds number. Observe that the elliptical fin shape yields the highest Nusselt number at all Reynolds numbers. Moreover, the elliptical pin fin ejects the highest heat transfer rate, which indicates the pin fin performance. Furthermore, skin friction has a significant function with variation in Reynolds number.

Investigation of Tip Temperature of a Ring Fashioned Fin for CI Engine Using Ansys Modeling

Abstract: As the name imply prolonged surfaces to extract most amount of heat via out the surfaces. There are such a lot of researcher check out the heat transfer from the C I engine by using the use of fins, however nobody can calculate the top temperature of fin and to formulate the result by way of using Finite Element approach. It's far very vital to transfer warmness from the C I engine .The warmth transfer coefficient may be decided the usage of superior FEA codes which include fluid mechanics .Those simplified terms constitute a aggregate of several elements ,which include powerful floor vicinity ,lateral fin conduction ,boundary layer formation and cloth conductivity. It's miles very difficult to modeled a hoop form fin .Each pin should be individually discredited ,increasing the modeling time significantly .On this studies we have to used simulation application will be advanced for predicting and optimizing thermal performance of different sorts of fin component like round fin, axial fin and we compare ring form fin with triangular profile .The end result of the ring form fin can be additionally in comparison with the ones axial fins and ring shape fin with triangular profile the use of finite detail evaluation software advanced on Ansys software. Apart from this we additionally look into the temperature size and thermal pressure distribution. Keywords: Geometric modeling, thermal stress distribution, triangular profile,

Abnormal trend in hot carrier degradation with fin profile in short channel FinFET devices at 14 nm node

This study investigates the impact of fin profiles under hot carrier stress, which defines different base widths: wide-base samples with the smallest slope, medium-base samples, and narrow-base samples with a larger slope. The performance of the narrow samples is better than the medium samples, regardless of transconductance, on-state current, subthreshold swing or drain-induced barrier lowering, demonstrating that the narrow profile samples’ mobility and gate control are better. In long channel devices, the trend of hot carrier degradation (HCD) is in agreement with previous references, and is dependent on the transverse electric field and the fin shapes. However, this trend does not exist for short-channel devices. Positive bias stress and technology computer aided design simulation are applied for investigation and to clarify the reasons for this abnormal HCD trend. Finally, by fitting the multiple vibrational excitation (MVE) mechanism, the slope of the trend lines in the short channel devices are found to indeed match the bending mode. In other words, the disappearance of the general trend between the HCD and fin profiles is caused by the change in the mechanism in the short-channel device. Because the MVE mechanism is independent from the electric field, the narrow profile fin shape more effectively promotes gate control and better performance without affecting the reliability in short channel devices. These results can provide a clear direction for fin shape designers in the future.

Study on thermal performance of a new optimized snowflake longitudinal fin in vertical latent heat storage

Taking the casing phase change heat storage unit filled with RT55 as the research object. According to the low thermal conductivity of phase change materials, we propose a Phase Change Material (PCM) sleeve with snowflake longitudinal fin structure to improve the melting performance of vertical latent heat storage system (LHTES), and the phase change heat transfer process is simulated by numerical simulation. We studied the enhanced heat transfer characteristics of the snowflake-shaped fin structure to the casing PCM unit, and compared with the ordinary rectangular longitudinal fin and the improved snowflake-shaped longitudinal fin. The results show that the combined mechanism of snowflake finned tube structure and local heat transfer of phase change materials can significantly shorten the charging time, which is 45.59% lower than that of traditional fin melting time. Reasonable changes in fin length, width, shape and angle structure can shorten the charging time, but reduce the heat storage. We analyzed the thermal performance of the heat storage system by taking the charging time, heat storage capacity and average heat flux as evaluation indexes, and discussed the effects of flow temperature in the tube, fin material and longitudinal fin shape on the melting performance of the system.

Two new species of the butterflyfish genus Roa (Perciformes: Chaetodontidae).

Two new species of Roa (Chaetodontidae) are described. Roa semilunaris sp. nov., based on six specimens from the Mascarene Ridge (south-western Indian Ocean), is most similar to Roa jayakari (Norman, 1939), distributed in the Red Sea and the northern Indian Ocean, in having scales on the upper jaw, interrupted pale lines within the second dark body band, and similar coloration and shape of the pelvic fin. However, the former is readily distinguished from R. jayakari by a wider whitish interspace between the second and third black bands [width of interspace at lateral line level 15.9%-18.5% of standard length (SL) in R. semilunaris sp. nov. (vs. 5.1%-8.5% of SL in R. jayakari)], with 9 or 10 pored lateral-line scales in the interspace (vs. 3-5); an oval or semicircular ocellated blotch on the soft-rayed portion of the dorsal fin (vs. a circular blotch); the head higher and longer [head length 35.0%-36.7% of SL (vs. 40.8%-44.1% of SL), head height 48.1%-50.5% of SL (vs. 52.0%-56.9% of SL)], and postorbital length 14.0%-15.1% of SL (vs. 17.0%-20.5% of SL). Roa uejoi sp. nov., based on three specimens from Guam (Mariana Islands), is most similar to Roa excelsa (Jordan, 1921) (now restricted to the Hawaiian Islands and Johnston Island), but is distinguished from the latter by having a circular dorsal-fin ocellated spot (vs. spot distinctly oval in the latter) and a much more elongate, filamentous first pelvic-fin soft ray, of length 119.0%-123.4% of 2nd ray (vs. not obviously filamentous, 104.9%-105.8%). A key to the eight valid species of Roa is provided.

Scyliorhinus hachijoensis, a new species of catshark from the Izu Islands, Japan (Carcharhiniformes: Scyliorhinidae).

A new species of catshark genus Scyliorhinus, S. hachijoensis sp. nov., is described for the islands of Mikurajima, Hachijojima, and Torishima in southeastern Japan. Scyliorhinus hachijoensis has clasper hooks, which is a common feature in males of the most closely related species (S. torazame), but is distinguished by its coloration (presence of dark spots), the height of its anal fin (higher than the caudal peduncle), and the shape of pectoral and pelvic fins, and dermal denticles. Molecular data also corroborates the new species as a distinct and monophyletic taxon by nucleotide sequence analysis of three mitochondrial DNA regions.

THE BEHAVIOR OF HEAT SINK-IMPINGEMENT COOLING WITH FLAT PLATE AND ARCED FINS MODELS

In this paper, a statistical analysis was applied to the numerical predictions of temperature distribution for the heat sinks. There are two types of heat sink with an array of impingement. The first type is a flat plate heat sink, and the second type is arcs-fins heat sinks. The second type category considers five models (A, B, C, D, and E). The shapes of fins were changed, but the thickness, distance between fins, and radius were held fixed for comparing and analyzing them depending upon the improvement of the fin geometry of heat sink. The heat sinks of the two types are subjected to multi impinging flow at different Reynolds numbers (7000-11000). Thermodynamic and hydraulic results were collected. The best model was calculated through a statistical analysis. The efficiency of an arcs-fin heat sink was superior to that of the flat plate heat sink. The findings of Model D were more appropriate than those of the other models. The concave arc near the heat sink's exit (model D) created better effect than the convex arc(model E), despite the fact that the (model D) shape fins being identical to (model E) shape fins (only rotated 180° at the same location). However, Descriptive Statistics manifested that in all situations, the mean temperature for (model D) is better than (model E). The results of comparison between the flat plate heat sink and models (D and E) evinced that the average heat sink temperaturein the suggested design reduced via 12%, 8%, while the (model E) decreased by 12%, 7% for Re (7000, 9000), respectively. In addition, the two models maintained the same percentage of (8% and 7%) improvement at Re (11000). The correlation coefficient between the flat plate and the arcs-fins heat sink for model B has the highest value (0.809), while model A has the lowest value of correlation (0.673).

Pool boiling simulation of two nanofluids at multi concentrations in enclosure with different shapes of fins

The boiling process is one of the important physical phenomena that is based mainly on the phase transformation of matter. As the importance of boiling has become great with the development of scientific physics in the present time due to the large number of its uses and benefit from it in physical processes. Where it became necessary to study and improve boiling in fluids and use nanomaterials to improve this boiling. Where in our research, the boiling of water at a temperature of 100 degrees Celsius was studied with the use of nanomaterials (CuO, Al2O3) and in different concentrations to understand their effect on the boiling process. With the addition of different shapes of fins that help to increase the surface area to add heat. Three shapes of rectangular, circle and triangle fins are used, which are the main shapes of the fins. The results show that with the increase in the concentrations of nanomaterials, the boiling process increases velocity of vapor and affects pressure and velocity of flow. The best shapes that give more area for the temperature and thus increase the boiling process and velocity compared to other cases that have been verified.

Study of Offshore Patrol Vessel Models for Seakeeping and Maneuvering Improvement using Anti-Rolling Fins

Offshore patrol vessel models using anti-rolling fins with variations of fin angle and shape are investigated in this study to improve the seakeeping and maneuvering performances, especially in the combat operation of the vessel. This study focused on the determination of the effect of adding fins to the seakeeping and maneuvering performances by optimizing fin angle and shape fitted on the ship hull. The 3D ship model with three variations of fin’s shape and four variations of the fin angle was analyzed using a numerical method of computational fluid dynamic (CFD) software. Result showed that fins type NAIAD 525, has the smallest average roll response occurs at 55 deg fin with motion amplitude 5.4E-05 deg. At the same fin angle, the average pitch amplitude reaches the smallest of 2.7E-03 deg. For PRAXIS type, the smallest average roll response occurs at 60 deg fin with motion amplitude 4.7E-05 deg. But for average pitch amplitude, the lowest value occurs at 45 deg of 2.7E-03 deg. And WESMAR type, the smallest average roll response occurs at 45 deg fin with motion amplitude 3.9E-05 deg. At the same fin angle, the average pitch amplitude reaches the smallest of 2.7E-03 deg. Turning maneuvers parameter of the vessel are comply with the IMO standard. The highest value of Tactical Diameter, which is 4.91 L, occurs in condition of no environmental disturbance, while the highest value of Advance occurs in wind disturbance condition with a value of 4.29 L.

Numerical investigation of modified fin shapes for the improved heat transfer

An examination of fin surfaces with various shapes was performed in this work to determine the most efficient heat transfer rate. Models, investigations, and studies have been conducted on the geometry of fin surfaces, namely normal fins with rectangular cross section (R-Fin), fins with multiple steps (S-Fin), and multiple step fins with dimples (D-Fin). Fin surfaces with higher surface area have improved heat transmission, as determined by conceptual and numerical investigation. According to numerical data, dimpled fins improve the surface region and heat transmission of the fins. The dimples had been constructed with changing diameters to fit the fins, which are 5 mm, 4 mm, and 3 mm in diameter, and have been evaluated using a static computational approach. The purpose of this study is to demonstrate the construction, evaluation, and outcome of several fin shapes with constant input boundary conditions. The spherical grooves with various diameters were found to be more successful than the other fins, and creating notches increased heat transmission far more than augmenting the size of the stepped fin's depression.