Bionic Fin Research Articles

Impact of Bionic Fins on Supercritical CO2 Serpentine Microtube in Various Flow Directions

Impact of Bionic Fins on Supercritical CO2 Serpentine Microtube in Various Flow Directions

Hydrodynamic Simulation and Experiment of a Self-Adaptive Amphibious Robot Driven by Tracks and Bionic Fins.

Amphibious robots have broad prospects in the fields of industry, defense, and transportation. To improve the propulsion performance and reduce operation complexity, a novel bionic amphibious robot, namely AmphiFinbot-II, is presented in this paper. The swimming and walking components adopt a compound drive mechanism, enabling simultaneous control for the rotation of the track and the wave-like motion of the undulating fin. The robot employs different propulsion methods but utilizes the same operation strategy, eliminating the need for mode switching. The structure and the locomotion principle are introduced. The performance of the robot in different motion patterns was analyzed via computational fluid dynamics simulation. The simulation results verified the feasibility of the wave-like swimming mechanism. Physical experiments were conducted for both land and underwater motion, and the results were consistent with the simulation regulation. Both the underwater linear and angular velocity were proportional to the undulating frequency. The robot's maximum linear speed and steering speed on land were 2.26 m/s (2.79 BL/s) and 442°/s, respectively, while the maximum speeds underwater were 0.54 m/s (0.67 BL/s) and 84°/s, respectively. The research findings indicate that the robot possesses outstanding amphibious motion capabilities and a simplistic yet unified control approach, thereby validating the feasibility of the robot's design scheme, and offering a novel concept for the development of high-performance and self-contained amphibious robots.

Structure optimization of intercooler bionic fins based on artificial neural network and genetic algorithms

The bionic fins inspired by the shark are proposed to enhance the thermal-hydraulic performance of the intercoolers in this work. The geometric parameters of the fins are investigated to examine the effects on thermal-hydraulic performance. The height and width of protrusions are chosen as optimization parameters based on the results of the geometric parameter analysis. Non-dominated genetic algorithms are combined with artificial neural networks to obtain the optimal solution for the geometry parameters. The artificial neural networks used in this study exhibit a reliable accuracy with errors below 10 % (with mostly remaining below 5 %). The optimal values for the height and width of the protrusions are determined to be 1.01 mm and 0.82 mm, which results in a Colburn factor of 0.01923 and a comprehensive index of 0.04305. Compared with the original design, the optimized structure yields 17.69 % and 4.77 % increments for the Colburn factor and comprehensive index. Compared with the original model, the intercooler with the optimal structure exhibits a 9.9 % increase in entropy generation and a 20.2 % enhancement in the exergy difference between the inlet and outlet.

Heat charge performance prediction and optimization of locally refined bionic fin heat exchanger with PCM and nanoparticles based on NSGA-II

Phase change energy storage plays an important role in the popularization of renewable energy sources (wind, solar, geothermal, etc.). However, previous studies have paid little attention to the correlation and optimal solution of phase transformation thermal performance prediction. This research combines Response Surface Methodology with the Non-dominated Sorting Genetic Algorithm II to forecast and enhance the performance of tree-shaped biomimetic latent heat storage units, targeting optimal functionality under operational conditions. Initially, the study delves into a mechanistic analysis of the heat transfer in latent heat storage units, focusing on the coupling of conductive and natural convective heat transfer during the melting phase. The synergistic enhancement of heat conduction and convection is realized through locally refined and punched fins. Subsequently, Response Surface Methodology was applied to analyze the interactions between the design variables and the objective functions, leading to the attainment of Pareto-optimal frontiers using the Non-dominated Sorting Genetic Algorithm II. The results demonstrate that the Pareto-optimal solutions substantially improved the Nusselt number of novel biomimetic latent heat storage units by 42.58%–45.58 %, relative to tree-shaped fin latent heat storage units. Concurrently, the Fourier number was reduced by 17.54%–19.22 %. Moreover, the effect of adding nanoparticles (aluminum, copper oxide, and copper) to the phase change material was studied. The results show that the proposed locally refined optimal fin structure is superior to the addition of nanoparticles.

Control mechanisms of different bionic structures for hydrofoil cavitation

Cavitation limits the efficient and stable operation of rotating machinery. The exploration of control methods for hydrofoil cavitation is important for improving the performance of hydraulic machinery. The leading-edge protuberances of the humpback flipper and the spine structure of the tail fin of sailfish are two common bionic structures for cavitation control; however, the control effects of both have limitations. Accordingly, in this study, a passive control method for hydrofoil cavitation was developed by combining the two bionic structures. With the large eddy simulation method, the cavitation processes of wavy leading-edge hydrofoil, bionic fin spine structure hydrofoil, and novel bionic combined structure hydrofoil were studied under a cavitation number of σ = 0.8. The control mechanisms of the three bionic structures for the hydrofoil cavitation were investigated. The results indicated that the novel bionic combined hydrofoil realised the superposition and complementation of the control effects of the two single bionic structures and achieved a better cavitation inhibition effect, reducing the total volume of cavitation by 43 %. In addition, it enhanced the stability of the flow field and reduced the standard deviation of the pressure coefficient on the suction surface by up to 46.55 %. This research provides theoretical support for the optimisation and modification of the blades of hydraulic machinery, such as propellers and pump turbines.

A Novel Squid-Inspired AUV Design: Revolutionizing Coral Reef Preservation Through CFD and Experimental Insights into Drag and Maneuverability

This study focuses on conceptualizing and optimizing an advanced bionic robotic solution to surmount the limitations of current observational vehicles in coral reef conservation. Human divers are traditionally subjected to physiological challenges, while current robotic alternatives grapple with operational impediments, including anthropogenic marine disturbances. Utilizing advanced robotics tailored for marine ecosystems with intricate topologies and fragile corals, this study aims to enhance conservation precision in the face of climatic shifts and marine pollution from anthropogenic activities.This paper develops a squid-inspired Autonomous Underwater Vehicle (AUV), whose behavior is then examined and improved utilizing both experiments and Computational Fluid Dynamics.(CFD). The governing equations considered here are the incompressible Reynolds-Averaged Navier-Stokes (RANS) with an iterative solver for both the pressure-Poisson and momentum equations. Apart from CFD analysis, a prototype was assembled and experimentally tested to validate the CFD outcomes and assess the lift from its bionic rudders. The maneuverability is optimized through careful designs and parameter studies of several features.A head length is determined to balance viscous and pressure drag while achieving the least total drag in the AUV design. Additionally, a disk is introduced at the AUV’s front, which reduces fluid contact, thereby decreasing the viscous drag. While this modification slightly increased pressure drag, it yielded an overall reduction in total drag. Experimental observations confirmed a propulsion speed and underscored the necessity for maximizing rudder extension.The developed AUV’s squid-like design, optimized via CFD, ensures drag reduction by 5.34% and energy efficiency. By mimicking squid dynamics, disturbances to marine biota are minimized. The incorporation of bionic fins, empirically fine-tuned, enhances the AUV’s agility. These attributes establish it as an exceptional prototype, setting a precedent for future coral reef monitoring systems and augmenting conservation strategies.

Design and thermal performance analysis of a new micro-fin liquid cooling plate based on liquid cooling channel finning and bionic limulus-like fins

As the current channel-type liquid cooling plate generally suffer from high pressure loss and low cooling efficiency, making electric vehicles have to face problems such as high battery pack temperature and short mileage. To solve the above problems with channelized liquid-cooled plate, the conventional liquid-cooled channel was first rectangularly finned, and the size of the fins was optimized by varying the longitudinal spacing ratio f/a and transverse spacing ratio w/b between adjacent fins. Results show that the liquid-cooled plate had the lowest average temperature and pressure drop and the best overall performance when the size of the fins in the corresponding directions and the size of the spacing between the corresponding directions were equal. Secondly, on the basis of the optimization, the preferred fin form was preliminarily biomimetic. CFD simulation results show that the bionic limulus-like fins (BLLF) were more effective, with pressure drop (ΔP) and average temperature (T_ave) improved to a certain extent, compared with the rectangular and oval conventional shape fins. Subsequently, the number of inlets and outlets and their layout positions were discussed. Then, in order to further improve the performance of the cold plate, according to the shape characteristics of the limulus, the scrambler fins were homogenized to form a central channel and two secondary channels were added diagonally upward, which continued to construct a new type of microfin for the bionic limulus, and a multi-objective optimization of the secondary channels was carried out with L, W, α, and β as the parameters. Compared with the original model, T_ave and ΔP of the optimal model were reduced by 1.69 °C (4.61 %) and 6.81 Pa (54.26 %). Finally, the effect of the variation of Reynolds number on the thermal performance was discussed. It can be seen that the bionic fin design approach obtained in this study will provide a reference for liquid-cooled channel finning optimization.

Leaf-vein bionic fin configurations for enhanced thermal energy storage performance of phase change materials in smart heating and cooling systems

In the present study, we investigated the effect of different structures of a novel leaf vein bionic fin and various arrangements in the tube on the complete melting time of phase change materials (PCM) in a triplex-tube thermal energy storage (TES) system. RT82 was adopted as the phase change material. The enthalpy-porosity method was employed for this numerical study. The numerical model was validated against experimental data from a previous reference. The simulation results demonstrate that the novel fins deliver significant reductions in the duration of complete melting. Based on fin-branched vein numbers of 1, 2 and 3, increasing the fin angle from 30° to 60° can reduce the complete melting time by up to 14.3%. Additionally, adjusting the fin arrangement can save up to 6.35% of the complete melting time. The proper arrangement of the fins can improve the heat transfer performance of the PCM. The non-dimensional quantities analysis of the calculated results shows that the melting time is negatively correlated with the non-dimensional angle. As the non-dimensional parameter, fin arrangement number decreases from 1, the complete melting time corresponding to the fins of different structures first decreases and then increases for the phase change material.

Numerical Simulation of Unsteady Hydrodynamic Characteristics of Bionic Fin

A long uncompressed fin driven by fin rays is designed in this paper, and its kinematic model is established. The SST K-ω turbulence model is used to solve the N-S equation of three-dimensional unsteady incompressible fluid, and the hydrodynamic characteristics of the uncompressed fin are studied. The results show that when the undulating fin is started, the velocity of the surrounding fluid gradually increases with the movement of the fin surface, and the fluid moves from the leading edge of the undulating fin to the back edge along the fin surface. A relatively obvious anti-Karman vortex street is formed on both sides of the fin, and a jet is formed at the tail of the fin to generate forward thrust.

Design and Hydrodynamic Experiment Research on Novel Biomimetic Pectoral Fins of a Ray-Inspired Robotic Fish

Bionic propulsion has certain advantages over traditional propellers. Much research on pectoral fins as bionic propellers for ray-inspired robots has been made, but rarely did they compare the hydrodynamic performance of different fins on the same platform to find out optimal balance. In this paper, the existing prototypes are categorized into three structure types, and a new bionic pectoral fin module used on a ray-inspired robotic fish was presented, together with a novel 2-DOF spatial parallel mechanism as the bionic propeller. Motion analysis of the mechanism agreed well with the pectoral fin kinematic model, providing a reliable basis to test different types of fins. Design and fabrication of the new bionic fin module as well as two traditional ones are also explained. Hydrodynamic experiment was conducted to study the differences between each fin type under various working conditions. Results indicate that the thrust generated by the fin oscillation is closely related to four parameters (amplitude, frequency, phase difference, and flow velocity), and there are optimal value ranges for better propelling performance when the frequency is around 0.5 Hz and phase difference is near 30°. Thanks to better profile preservation and hydro force interaction, the newly proposed pectoral fins had higher performance than the traditional ones in terms of thrust generation and controllability when the amplitude is higher than 30° and frequency is over 0.3 Hz. An average thrust of 2.98 N was recorded for the new fin module at the max amplitude of 60°, 11.6% and 16.4% higher than the other two comparative test groups, respectively.

Design and Experimental Research on a Bionic Robot Fish with Tri-Dimensional Soft Pectoral Fins Inspired by Cownose Ray

Bionic propulsion has advantages over traditional blade propellers, such as efficiency and noise control. Existing research on ray-inspired robot fish has mainly focused on a single type of pectoral fin as bionic propeller, which only performed well in terms of pure speed or maneuverability. Rarely has the performance of different fin types been compared on the same platform to find an optimal solution. In this paper, a modularized robot fish with high-fidelity biomimetic pectoral fins and novel multi-DOF propelling mechanism is presented. A kinematic model of the pectoral fin based on motion analysis of a cownose ray is introduced as guidance for the propelling mechanism design. A high-fidelity parametric geo-model is established and evaluated based on statistical data. The design and fabrication process of the 3D soft bionic fins, as well as the robot platform, is also elaborated. Through experiments comparing the performance of different fin types constructed with different materials and approaches, it was found that the new soft fins made of silicon rubber have better performance than traditional fins constructed with a flexible inner skeleton and a permeable outer skin as a result of better 3D profile preservation and hydrodynamic force interaction. The robot ray prototype also acquires a better combination of high speed and maneuverability compared to results of previous research.

Nonlinear Error Feedback Positioning Control for a Pneumatic Soft Bionic Fin via an Extended State Observer

This paper presents a nonlinear error feedback controller for a pneumatic soft bionic fin based on an extended state observer. Manufacturing process is shown for a bionic stingray with the pneumatic soft bionic fin. A test experiment is carried out for a driving part in the pneumatic soft bionic fin by upper chamber inflated and lower chamber inflated with different internal pressures. A dynamic nonlinear system is established for the pneumatic soft bionic fin by test experiment results and kinematic modeling. Total disturbances of the dynamic nonlinear system are estimated and compensated by the extended state observer and the nonlinear error feedback controller, respectively. Moreover, both the convergence of the extended state observer and stability of the dynamic nonlinear system are proved by Lyapunov approach. Finally, simulation results are shown to verify the effectiveness of the proposed control method for the pneumatic soft bionic fin.

Influence on Fluid Flow and Heat Transfer of a Bionic Fin in Plate-fin Heat Exchanger

Influence on Fluid Flow and Heat Transfer of a Bionic Fin in Plate-fin Heat Exchanger

Research on Under-actuated Flexible Pectoral Fin of Labriform Fish

The new propulsor, whose inspiration is from pectoral fins of fishes, has arisen increasing attention. To improve the performance of the existing labriform bionic pectoral fin, based on the structure and control mechanism of real fish pectoral fin, the under-actuated technology was utilized to design a new flexible bionic pectoral fin. Then, the kinematic model of pectoral fin during fish forward steady swimming and the dynamic model of bionic pectoral was built. Finally, Matlab was used to simulate the kinematic and dynamic performance of bionic pectoral fin. The simulation result shows that the new flexible bionic pectoral fin can imitate the propulsion motion morphology of pectoral fin during fish forward steady swimming well. However, due to the restriction of kinematic model of pectoral fin and structure as well as physical properties of bionic fin ray, there is still tolerance between the locomotion morphology of bionic pectoral fin and that of real fish. Therefore, it is necessary to develop further research on kinematic modeling of pectoral fin and bionic design of fin ray. Additionally, the new bionic pectoral fin reduces the number of the driving variables, providing the possibility and the basis of further reducing the volume as well as the complexity of bionic device of pectoral fin.

Design Optimization of a Bionic Fish with Multi-Joint Fin Rays

This paper aims to design a novel bionic fish propelled by oscillating paired pectoral fins. Flapping motion deformation of the nature sample, the cow-nosed ray, is realized with simple mechanical structure through optimization. Locomotion analysis of the nature sample under linear cruise swimming conditions is carried out. Simplified mathematical models of the pectoral fin are obtained to be the design foundation of the bionic fin rays and the bionic fish. The number of fin rays is decided according to the passing kinematic wave shape and number. Distance and structure parameters are optimized, and determined by the minimum area error method. A novel two-stage slide–rocker mechanism is designed to fulfill the driving requirements with only one servo motor. System design of a new bionic fish robot is presented, including the mechanical design and the control method. Main bionic characteristics extracted from the cow-nosed ray are fulfilled by the prototype and verified by experiments.

Modeling and Hydrodynamic Characteristics of Bionic Undulate Fin Propeller Driven by Hydraulic

The bionic undulating propeller driven by hydraulic system has different structure, kinematic and dynamic characteristics than that of the common bionic undulating propellers driven by other sources. This paper highlights firstly the structure and driving mechanism of bionic undulating propeller with a hydraulic system, and then setup its kinematic model, based on ruled-surface equation. Changing rules of dynamic mesh for bionic fin is designed based on kinetic model. Later on, the changing courses of hydrodynamic force caused by the bionic undulating fin are calculated and studied with the CFD (Computational Fluid Dynamics) method, as well as the changing characteristics of the fluid pressure field. The analysis showed that while driven by hydraulic system, the bionic propeller could produce full-baseline undulating motion, and has flexible start-up process, as well as doubled-frequency character. The bionic undulating fin driven by hydraulic system puts up flexible characters on both kinematic and dynamics. Key Words: Hydraulic Driven; Undulating Fin; Bionic Propeller; Dynamic Mesh; Hydrodynamics

Modeling and Control of a Bionic Bladder System Designed for Bionic Underwater Robots

Bionic underwater robot is a new-type underwater r obot which propelled and controlled by several bion ic fins. Heaving motion is an indispensably function f or most bionic underwater robots. Bionic bladder sy stem is an apparatus which can realize both heaving and pitchi ng control. It was inspired by biologic fish's blad der. It was composed of a cylinder, a piston, a pipe, a rolling guide, two ball screws and two servomotors. The dynamic models of the bionic bladder system for heaving and pitchi ng motion were established and based on which a dual-velocity control system was designed. Two control channels r ealized decoupling by setting different control cyc les, and a PID controller are designed for each control channel. S imulations with the real design parameters and diff erent control cycles were performed. Results indicated that the b ionic bladder system can get a good control perform ance with proper control parameters.

Experimental Study and Hydrodynamic Performance Analysis of a Bio-Tail Fin Propellant System

In order to research the bionic mechanics in unsteady flow and the hydrodynamic performance of the oscillating tail fin, in this paper, an experimental device imitating bionic tail fin were built, the design concepts and the rolling systems of the mechanical tail fins were demonstrated, including the procedures and correlated works on the selection of the servo motors, online control and signal data collecting and processing. The movements of the mechanical tail fin could be optimized by the comparisons of the propulsion efficiency, thrust coefficient, lateral force coefficient and torque coefficient at different conditions. Meanwhile, error analysis is carried out to correct the movement curves and obtain more precise experimental data and results.