Fin Type Research Articles

Experimental investigation of heat transfer in aluminum wings with NACA 4040 profile

Heat transfer is a working area where different numerical results are obtained from different materials, different environments, independent observations are made, data can be collected at different bases based on the abundance of data input. effects on heat transfer. The effects of air flow, air temperature and air pressure on heat transfer were discussed. Unlike the previous studies, the construction of the fin is made of aluminum and the choice of the NACA 4040 wing profile as the shape of the fin was one of the major factors in the differences in the test output. Since the results obtained from the experiments included many products or development factors in the application and production areas that are important, the fact that this study was carried out with aluminum material and the results of the experiments in this direction became a factor increasing the circulation in these processes. In our studies, one type of fin was used.

Thermal analysis of heat transfer with different fin geometry through straight plate-fin heat sinks

The benefits of using straight parallel -fin heat sinks with add and subtract fins are study by utilizing experimental and Computational simulation methods. Three-dimensional numerical simulations with different parameters were studied. Numerical simulations studied two types of straight plate fins: first model is straight plate-add fin heat sinks and second model is straight plate-subtract fin heat sinks. Experiments are studied with three shapes for the same dimensional numerical simulations: straight plate, straight with add semicircular and straight with subtract semicircular fin in turbulent forced-convection for Reynolds number in the range of 6300–35,120 and heat flux 1194–23353 W/m2. It is noticed from results that heat transfer coefficient show a good agreement between numerical simulation and experimental tests and increases at about (38%, 43%) for straight with added semicircular and straight with subtract semicircular fins when compared with straight than other shapes fins. Additionally, Nusselt number increases at about (21% and 32%) for straight with added semicircular and straight with subtract semicircular fins when compared with straight than other shapes fins.

Thrust and efficiency enhancement scheme of the fin propulsion of the biomimetic Autonomous Underwater Vehicle model in low-speed flow regime

Efficient low-speed Autonomous Underwater Vehicles (AUV) could adopt a propulsion mechanism with a biomimetic approach of caudal fin propulsion. The developments of the biomimetic AUV have very little attention to the systematic enhancement scheme of the fin performance. Therefore, many unclear relations of the parameters in thrust generation and efficiency of the various types of biomimetic fins. The present study proposes a systematic enhancement scheme of the static and dynamic performances of the biomimetic fins in a low-speed regime. This scheme involves rigid, cupping, and flexible single-joint fins of the acceleration-reaction fin mechanism and a high aspect ratio lunate shape two-joint fin of the lift-based fin mechanism. Average net-force and Thrust-to-Power Ratio evaluated the static performance, while the estimated cruising speed characterized the dynamic performance. The present study shows that the flexible single-joint fin improved the maximum values of the rigid fin performance by three times in average net-force, five times in thrust-to-power ratio, and two and a half times in estimated cruising speed. The two-joint fin enhanced the static and dynamic performances of the flexible fin by three times in average net-force, four times in thrust-to-power ratio, and one and a half times in estimated cruising speed. The present study suggests that flexibility has a role as a thrust vectoring factor. Furthermore, the lift-based mechanism in the two-joint fin provides effective and efficient thrust generation. In the present study, the two-joint fin was the effective and efficient fin propulsion mechanism in a low-speed regime.

A CASE STUDY ON STABILISER FIN-HULL INTERACTION USING CFD AND MODEL EXPERIMENTS

A case study was conducted to investigate and quantify stabiliser fin-hull interaction using a combination of Computational Fluid Dynamics and physical model experiments. The fin-hull interaction was studied by comparing the lift and drag of a stabiliser fin in a free stream condition and when attached to a hull. The findings of this case study showed that using free stream fin characteristics to predict performance of a stabiliser fin fitted to the hull resulted in an over-prediction of drag by up to 46% and under-prediction of lift by up to 75% for the speeds and angle of attack analysed. These discrepancies are for this case study only and in practice will vary for different hull forms, fin types, fin location and angles of attack. However, the research highlights the limitations of using free stream fin characteristics to predict the performance of a fin fitted to a hull.

Numerical study on enhanced melting heat transfer of PCM by the combined fractal fins

The melting heat transfer characteristics of PCM were studied in different combined types of heat exchangers. The effect of combining two different bifurcation level fractal fins was considered for PCM melting heat transfer in a phase change heat exchanger. Based on fractal theory and enthalpy-porosity method, a PCM melting model of two-dimensional unsteady heat transfer was established in a combined fractal fin heat exchanger. The influences of some factors, such as combined types of fractal fins, bifurcation level, heat transfer area of the fins and the spacing of the fins, were discussed for the melting heat transfer process. The results show that the complete melting time of PCM in a combined fractal fin heat exchanger is reduced by 68% compared with the traditional fractal fin heat exchanger. The melting time shows decreasing first and then gradually stabilizing as the bifurcation level number and heat transfer area of the combined fractal fins increase. The melting rate of PCM is the fastest in the Case 4 heat exchanger, and the complete melting time of PCM is the shortest in the Case 3 heat exchanger. Fin spacing and heat transfer area have a significant impact on the complete melting time. On this basis, the thermal performance coefficients between the fins zone and PCM zone are defined. The complete melting time of PCM is found to be exponentially negatively correlated with the thermal performance coefficient by curve fitting. The temperature distribution uniformity coefficient is proposed to evaluate the temperature distribution uniformity during the melting process of PCM. It is found that the temperature distribution uniformity of Case 2 has the best at the end of melting. The above results provide a theoretical basis for structural design of the heat exchanger with combined fractal fins to enhance PCM melting heat transfer.

Design and Realization of Labriform Mode Swimming Robot Based on Concave Pectoral Fins

A Swimming performance underlies the biomechanical properties and functional morphology of fish fins. In this article, design and realization of a swimming robot propelled by a pair of pectoral fin is implemented. The suggested shape of the pectoral fins is concave; this type of fin provides a simple approach in generating effective hydrodynamic thrust force through only one degree of freedom (1-DOF). Next, we show the effect of varying fin oscillation speed in two phases, the first phase is the power stroke one, where the fins start to push toward the backward of the body, and the recovery phase, where the fins return toward the frontal part of the body. The detailed steps of the robot design are presented and the thrust force exerted by pectoral fins has been evaluated. The robot is consisting of a rigid-body with an elliptical cross-sectional area, which helps in minimizing the water resistance during the thrusting process. Since pectoral fins provide a vital role in the propulsion mechanism of Labridae fish, the proposed model is driven by a pair of concave-shaped fin to simulate labriform mode swimming mechanism. For motion control, we have suggested to use PID controller in order to improve the system performance. The kinematic and dynamic model of a swimming robot has been derived based on Newton-Euler equations, while an evaluation of the total hydrodynamic forces that are exerted on the swimming robot's body is studied via the computational fluid dynamics (CFD) method. The proposed design has been validated theoretically via Solidworks{\textregistered} platform and examined experimentally. The results of the simulation and practical experiments showed the validity and agility of Labriform swimming robot.

Season and species influence stable isotope ratios between lethally and non-lethally sampled tissues in freshwater fish.

The field of stable isotope ecology is moving away from lethal sampling (internal organs and muscle) towards non-lethal sampling (fins, scales and epidermal mucus). Lethally and non-lethally sampled tissues often differ in their stable isotope ratios due to differences in metabolic turnover rate and isotopic routing. If not accounted for when using non-lethal tissues, these differences may result in inaccurate estimates of resource use and trophic position derived from stable isotopes. To address this, the authors tested whether tissue type, season and their interaction influence the carbon and nitrogen stable isotope ratios of fishes and whether estimates of species trophic position and resource use are affected by tissue type, season and their interaction. This study developed linear conversion relationships between two fin types and dorsal muscle, accounting for seasonal variation. The authors focused on three common temperate freshwater fishes: northern pike Esox lucius, yellow perch Perca flavescens and lake whitefish Coregonus clupeaformis. They found that fins were enriched in 13 C and depleted in 15 N compared to muscle in all three species, but the effect of season and the interaction between tissue type and season were species and isotope dependent. The estimates of littoral resource use based on fin isotope ratios were between 13% and 36% greater than those based on muscle across species. Season affected this difference for some species, suggesting the potential importance of using season-specific conversions when working with non-lethal tissues. Fin and muscle stable isotopes produced similar estimates of trophic position for northern pike and yellow perch, but fin-based estimates were 0.2-0.4 trophic positions higher than muscle-based estimates for lake whitefish. The effect of season was negligible for estimates of trophic position in all species. Strong correlations existed between fin and muscle δ13 C and δ15 N values for all three species; thus, linear conversion relationships were developed. The results of this study support the use of non-lethal sampling in stable isotope studies of fishes. The authors suggest that researchers use tissue conversion relationships and account for seasonal variation in these relationships when differences between non-lethal tissues and muscle, and seasonal effects on those differences, are large relative to the scale of isotope values under investigation and/or the trophic discrimination factors under use.

Heat transfer analysis on different pin fin types using Solid Works

A fin is an extended part of an object whose purpose is to raise the rate of heat transfer mainly by convection. The heat flow in any object depends on the surface area, temperature difference, and convection coefficient. As convection coefficient cannot vary after a certain limit and temperature difference depends on the process, the way to increase the rate of heat transfer is to increase surface area which was done by adding fins. In this study, steady-state thermal analysis is performed on different types of fins and fins of different heights by using Solid works simulation. Different materials of fins are also used to verify results as the rate of heat transfer is independent of material. Aluminum 6061 and Copper is used as material for rectangular and cylindrical pin fins. In comparison, rectangular pin fin has a high rate of heat transfer as compared to copper pin fin, and also the rate of heat transfer is directly proportional to the height of the fins irrespective of the profile.

Multi-physics modeling of thermochemical heat storage with enhance heat transfer

• A multi-physical model of CaO/Ca(OH) 2 hydration process is simulated. • Thermal conductivity of solid-phase has a significant effect on hydration process. • Relationships between fins and reaction are explored. • Axial fins shorten the exothermic time to 83.4%. Thermochemical heat storage technology is an important component in energy system, and plays a key role in the balance of energy supply and demand. A multi-physics model is constructed to study the hydration process in a tubular reactor, including fluid flow, heat transfer and reaction. Variations of temperature and conversion of CaO are discussed in detailed to reveal exothermic reaction characteristics. Besides, effects of different reaction conditions during hydration are studied, such as porosity, temperature, pressure, flow rate and thermal conductivity. It is found that the low thermal conductivity of solid-phase is the most important factor which limits the reaction. The heat transfer process can be greatly promoted by adding fins, due to the high heat conductivity. However, the relationship between the reactor structure and the performance of the thermochemical heat storage is not quantitatively clear. The present study aims to investigate the impact of the arrangement of fins on the hydration process. Finally, different types of fins with high thermal conductivity are employed in the reactor. Attributing to the fact that the equilibrium temperature is affected by the vapor pressure, thermochemical reactors with different fin configurations have different flow characteristics and pressure drops, leading to different reaction characteristics. It is shown that the exothermic time was reduced to 84.32% (axial fins), 89.97% (radial fins), and 88.71% (spiral fins) of the original, respectively. This study can reveal the coupling relations of multi-physics fields in thermochemical heat storage, and provide theoretical basis for the design of thermochemical heat storage reactors.

Flow analysis in seamless hot-extruded pipes with helical inner ribbing surface

The article is devoted to numerical simulation of heat transfer processes occurring during the flow of a coolant in seamless hot-extrusion pipes with a spiral inner fin surface (TMK-IRS). A description of the numerical modeling technique is given along with the interface of the program used to create different types of internal fins. Thermohydraulic analysis of finned pipes for transient, turbulent and laminar flow regimes has been carried out. An estimate of the critical Reynolds number characterizing the transition to a turbulent regime, the nature of the transient flow regime in comparison with other classical cases is given.

A Rotor Cooling Enhanced Method for Axial Flux Permanent Magnet Synchronous Machine With Housing-Cooling

This paper focuses on the rotor thermal design of the axial flux permanent magnet synchronous machine (AFPMSM) with housing water-cooling. By adapting the effect of disc rotor self-ventilation, an enhanced cooling method has been innovated to optimize the temperature distribution of the rotor in AFPMSM. Two scenarios will be created to compare their influence on cooling enhancement of rotor with the diverse types of fins, the annular fin and the rectangular fin, each will be installed separately to the internal surface of housing. There is a significant effect by using this method in all types of AFPMSM with housing cooling, especially for multi-rotor ones. The results of CFD show that the effectiveness of annular fins is essentially enhanced, with 25% more heat dissipation achieved.

Effect of Pitch Ratio and Diagonal Length of Pin Fin of Heat Sink on Convective Heat Transfer for Turbulent Flow Condition

In this study, the impact of pitch ratio and diagonal length of pin fin on the heat sink has been numerically investigated to determine the thermo-hydraulic performance of heat sink under turbulent flow regime. Usage of pin fin on the heat sink has been preferred due to less pressure drop in comparison with general fin type. While the pitch ratio has been changed 0.75 ≤ P/e ≤ 1.1, the length of edge of fin has been changed 3 ≤ Lef ≤ 6 as geometric parameters. The working range of the study has been considered as turbulent flow regime (2658 ≤ Re ≤ 7138). The computational study has been carried out on ANSYS Fluent 2020R2 using SST k-ω with low-Re correction model to calculate RANS equations. The factors, which define thermo-hydraulic performance of the study, such as average Nusselt number, average Darcy friction factor, and thermal resistance has been elucidated in detail. Also, to detect flow characteristics comprehensively, the contours have been created for vorticity, temperature, and velocity streamline. As a results of overall assessment of this study, it is concluded that the maximum convective heat transfer performance has been obtained using Case 12 by 52% compared with the Case 1 at Re=7138.

Heat transfer enhancement of finned‐tube heat exchanger using nozzle‐ and diffuser‐shaped fins instead of straight fins

AbstractIn this paper, a new method has been used to improve the heat transfer rate in the finned‐tube heat exchanger with nozzle‐ and diffuser‐shaped arrangement. For this study, the effect of several parameters was studied numerically. For the computational fluid dynamics simulation, the continuity, momentum, and energy equations were solved by the finite volume method using the standard k–ԑ model. The rate of heat transfer increases with the decreasing of fin bend radius (15 < Rfb < 20) for both nozzle‐shaped fin and diffuser‐shaped fin. By increasing of side temperature (600 < Tside < 900) and side Reynolds number (2000 < Reside < 5000) the heat transfer rate increased for both nozzle‐ and diffuser‐shaped fins. Results showed that a nozzle‐shaped fin with a fin bend radius of 15 mm under the condition of Rein = 20,000, Tside = 900 K, and Reside = 3400 has a higher effect on heat transfer in comparison with the other types of fins. The maximum heat transfer rate was almost 39% and 35% for the nozzle‐shaped fin with a bend radius of 15 mm and diffuser‐shaped fin with a bend radius of 15 mm compared with the simple tube, respectively. Finally, correlational equations have been suggested to forecast the average Nu number as functions of various parameters of the tube equipped with different types of outer fins involving nozzle‐ and diffuser‐shaped.

Heat transfer factor j and friction factor f correlations for offset strip fin and wavy fin of compact plate-fin heat-exchangers

A unique model of heat transfer factor "j" and friction factor "f" are developed for different types of fins, which are rectangular offset strip fin, rectangular wavy fin compact heat exchangers by considering the geometric variables such as plate space (Hp), fin pitch (Pf), hydraulic diameter (Dh), wave amplitude (Aa), fin length (λ), and Reynolds number (Re). The proposed j and f models provided 98% of experimental data points within ±20% and 82.3% of experimental data points within ±10% accuracy for OSF fins. Also, they provided 100% of Kays and London's experiential data points within ±5% accuracy for wavy fins. These proposed j and f models for a wide range (120–10000) of Reynolds number flows, including laminar and turbulent flows. j model provides maximum RMSPE 15% and 2% accuracy values for PFHE offset strip fins and wavy fin geometries, respectively. f model provides maximum RMSPE 17% and 3% accuracy values for PFHE offset strip fins and wavy fin geometries, respectively. Based on RMSPE and experimental data analysis, proposed j and f models were validated and better than existing models for offset strip fins and wavy fins.

Analysis of increase in efficiency of air-cooled heat exchangers due to intensification of heat exchange

Currently, the issues of improving the heat transfer processes in air-cooled heat exchangers play a huge role in terms of increasing the cooling efficiency and thus reducing the size of heat exchangers. This significantly saves resources. There are several basic methods for increasing the heat transfer of fluids in air coolers, for example, such as: finning of tubes and heat exchange intensification with the help of tube inserts. The purpose of the study is to analyze the efficiency of different fin types and the use of tube inserts, as well as changes in the heat transfer coefficients of air and natural gas, depending on the changes in the types of fins and tube inserts, and their geometry. The application software is Xchanger Suite provided by the company HTRI to ITMO University. The result is the optimally selected geometry of the heat exchange intensifiers based on the analysis, what allows reducing the dimensions of the air- cooled heat exchangers, while providing the necessary heat load, the heat exchange surface reserve coefficient and the heat transfer coefficients.

Shape memory alloy-driven undulatory locomotion of a soft biomimetic ray robot

The objective of this study was to imitate undulatory motion, which is a commonly observed swimming mechanism of rays, using a soft morphing actuator. To achieve the undulatory motion, an artificial muscle built with shape memory alloy-based soft actuators was exploited to control the shape-changing behavior of a soft fin membrane. Artificial undulating fins were divided into two categories according to the method of generating the wave motion: single and multiple actuator-driven fins. For empirical research on the transformation and propulsion behavior of each fin type, the design and construction of bound propulsors were undertaken to mimic the structural and behavioral aspects of animals. To visualize the effect of undulatory motion on the swimming efficiency test of the fin beat frequency, a simplified soft undulating fin with a rectangular propulsor was constructed and tested. Additionally, dynamic modeling of the fin tip in wave-traveling was conducted for comparison and optimization. To optimize the thrust and propulsion efficiency of robot speed, the effects of the wave amplitude control and actuator sequence on the fin behavior were examined. An untethered robot was constructed according to the experimental results of the propulsors. Both exhibited exceptional swimming efficiency and maneuverability. The multiple actuator-driven ray robot exhibited a maximum swimming speed of 0.25 body lengths per second which is almost a similar swimming speed with previously reported robots. The developed robot achieved directional swimming (forward and backward) and turning (including rotation). Underwater exploration in an artificial environment was performed using the robot.

Numerical investigation on fin configuration improvement of 2 K sub-atmospheric plate-fin heat exchangers for the superfluid helium cryogenic systems

• The corrugated-serrated fin was proposed for the first time as a new type of fin. • A new structural parameter Lw number was defined to better describe the fin. • Numerical model under low temperature conditions was established. • The performance of corrugated, serrated and corrugated-serrated fins was compared. In order to improve the flow and heat transfer performance of 2 K sub-atmospheric pressure plate-fin heat exchanger, a new type of corrugated-serrated fin is proposed by combining corrugated and serrated fin. The Lw number is defined as a new structural parameter to describe the new type of fin. The numerical model of flow and heat transfer in the fin channels takes into account the influence of low temperature conditions with variable physical properties and has been fully verified by experimental data. Numerical investigation is performed to study the thermohydraulic characteristics of serrated fin, corrugated fin and corrugated-serrated fin. Meanwhile, three performance evaluation criteria Colburn factor j , friction factor f and TE-factor are used to qualitative compare their flow, heat transfer and overall thermo-hydraulic performance. The results reveal that the heat transfer performance of new corrugated-serrated fins is the best. Colburn factor j of the new fins increases by 19.97%~38.22% compared with corrugated fin, and increases by 25.09%~33.83% compared with serrated fin. The flow performance of the corrugated-serrated fin is slightly worse, but the overall thermo-hydraulic performance is better, especially at low Reynold number. Besides, the effects of various structural parameters on the thermohydraulic characteristics of the corrugated-serrated is obtained. The conclusions provide theoretical guidance on the design of 2 K sub-atmospheric plate-fin heat exchanger.

Computer Assisted design and performance analysis of fin type phase change hot water storage tank

The numerical simulation of the fin-type phase-change hot water storage tank is carried out and the influence of different fin height and number of fins on the heat storage characteristics of paraffin wax/expanded graphite is explored by using ANSYS software in this paper. The results indicate that during the heat storage process, the closer to the copper tube and the fins, the faster the temperature change rate. The higher the fin height, the faster the temperature change rate at the same measuring point. At the same time, the increase in the number of fins is not positively correlated with the temperature rate of each measuring point.

Heat transfer and pressure drop in turbulent nanofluid flow in a pin-fin heat sink: Fin and nanoparticles shape effects

In this paper, the turbulent flow of a nanofluid in a channel is simulated in the presence of a pin-fin heatsink. Pin fins have different shapes, including hexagonal, circular, square, and triangular that are considered in two different arrangements. Constant heat flux is applied to the heatsink from its bottom due to the operation of an electronic chip. The nanoparticles suspended in water are alumina, which are in different shapes such as blades, bricks, cylinders, and plates. Their shape effect is investigated. The nanofluid enters the channel at a constant velocity in the range of 1–3 m/s and a constant volume percentage of 2%, and exits after cooling the pin-fin heatsink. The standard k-ε turbulence model is used to model turbulent flow, and the SIMPLEC method is employed to linearize the equations. The variables include fin type, fin arrangement, nanoparticle shape, and nanofluid velocity. Their effect on the maximum and average heatsink temperature and pressure drop (ΔP) is studied. The results show that increasing the velocity leads to a reduction in heatsink temperature, and the use of brick-shaped nanoparticles and circular fin results in the best cooling performance. Also, the use of circular fin and brick nanoparticles requires less ΔP than other cases.

The Performance of the hairpin type U Shape Double pipe heat exchanger type under effect of using Passive and Active Techniques.

The process of improving and developing heat exchanger performance has received a lot of attention, and efforts are still being made by specialized researchers and engineers with a huge investigations to increase rate of heat transfer to lessen the volume size and price cost of the factories apparatus accordingly. In this experimental study, a suitable heat exchanger equipped with flow meters and thermocouples for measuring flow rates and temperatures was used with the U shape hairpin type exchanger. The bending and angle of curvature of the tubes causes vortex flow, which greatly aids to attractive the rate of heat transfer process and increase the performance, The effect of active and passive techniques with different positions of the U shape Exchanger like position (U shape and Inverse U shape ) as parallel coupling with tube liquid in series is investigated during this study. passive technique represented using the O ring fin type. and an active technique represented by the injection of an air bubble by a small compressor through a special air diffuser. The results show that the best application was with inverse U shape (∩) and the performance enhanced about (19.1%) in the case of active techniques while and (11.1%) with passive techniques and by applying both techniques together, the overall enhancement was (30.272%), So this study provides new visions for further studies.