scholarly journals CFD Modelling and Optimization Procedure of an Adhesive System for a Modular Climbing Robot

2020 ◽  
Author(s):  
Miguel Hernando ◽  
Virgilio Gómez ◽  
Alberto Brunete ◽  
Ernesto Gambao
Keyword(s):  
Power Consumption ◽  
Numerical Models ◽  
Optimization Procedure ◽  
Adhesive System ◽  
Power Calculation ◽  
Cfd Modelling ◽  
Consumption Ratio ◽  
Adhesion System ◽  
Infrastructure Inspection ◽  
Modelling And Optimization

Adhesion systems are very important in robots for infrastructure inspection (especially in vertical walls). They present the challenge of optimizing the ratio vacuum/power consumption in battery-powered robots. In this paper a CFD (Computer Fluid Dynamics) modelling and optimization process of a robot adhesion system is carried out to determine the best performing configuration in terms of vacuum and power consumption. Analytical and numerical models were developed to predict the behaviour of the system for different configurations. The models were validated, using test rig measurements, by calibrating an arbitrary defined inlet height that simulates the leakage flow. Then, different geometric parameters were varied to determine the best performing configuration based on the vacuum/power consumption ratio value. The model presented in the paper was capable of predicting the behaviour of the system for different configurations, with a margin of error of 15% for the vacuum prediction and a 25% for the motor power calculation. Finally, the model was used to optimize parameters of the system, like the number of blades of the impeller. The adhesion system was conceived for the modular autonomous climbing legged robot ROMERIN.

scholarly journals CFD Modelling and Optimization Procedure of an Adhesive System for a Modular Climbing Robot

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1117
Author(s):  
Miguel Hernando ◽  
Virgilio Gómez ◽  
Alberto Brunete ◽  
Ernesto Gambao
Keyword(s):  
Power Consumption ◽  
Numerical Models ◽  
Optimization Procedure ◽  
Adhesive System ◽  
Power Calculation ◽  
Cfd Modelling ◽  
Consumption Ratio ◽  
Adhesion System ◽  
Infrastructure Inspection ◽  
Modelling And Optimization

Adhesion systems are very important in robots for infrastructure inspection (especially in vertical walls). They present the challenge of optimizing the ratio vacuum/power consumption in battery-powered robots. In this paper, a CFD (computer fluid dynamics) modelling and optimization process of a robot adhesion system is carried out to determine the best performing configuration in terms of vacuum and power consumption. Analytical and numerical models were developed to predict the behaviour of the system for different configurations. The models were validated, using test rig measurements, by calibrating an arbitrary defined inlet height that simulates the leakage flow. Then, different geometric parameters were varied to determine the best performing configuration based on the vacuum/power consumption ratio value. The model presented in the paper was capable of predicting the behaviour of the system for different configurations, with a margin of error of 15% for the vacuum prediction and 25% for the motor power calculation. Finally, the model was used to optimize parameters of the system, like the number of blades of the impeller. The adhesion system was conceived for the modular autonomous climbing legged robot ROMERIN.

scholarly journals Thermal-Structural Design of Actively-Cooled Panels Reinforced by Light-Weight Truss Cores

2013 ◽  
Author(s):  
Hongwei Song ◽  
Mingjun Li ◽  
Chenguang Huang ◽  
Xi Wang
Keyword(s):  
Heat Transfer ◽  
Structural Analysis ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Environment ◽  
Numerical Models ◽  
Lightweight Design ◽  
Optimization Procedure ◽  
Combustion Gas ◽  
Design Variables

This paper focuses on thermal-structural analysis and lightweight design of actively-cooled panels reinforced by low density lattice-framed material (LFM) truss cores. Numerical models for actively-cooled panels are built up with parametric codes to perform the coupled thermal-structural analysis, considering the internal thermal environment of convective heat transfer in the combustor and convective heat transfer in the cooling channel, and internal pressures from the combustion gas and the coolant. A preliminary comparison of the LFM truss reinforced actively-cooled panel and the non-reinforced panel demonstrates that the thermal-structural behavior is significantly improved. Then, an optimization procedure is carried out to find the lightest design while satisfying thermal deformation and plastic strain constraints, with thicknesses of face sheets and topology parameters of LFM truss as design variables. The optimization result demonstrates that, compared with the non-reinforced actively-cooled panels, weight reduction for the panel reinforced by LFM truss may reach 19.6%. We have also fabricated this type of actively-cooled panel in the laboratory level, and the specimen shows good mechanical behaviors.

A Study of the Behaviour of a Single-Bladed Waste-Water Pump

2006 ◽  
Vol 220 (2) ◽  
pp. 79-87 ◽  
Author(s):  
J Keays ◽  
C Meskell
Keyword(s):  
Waste Water ◽  
Power Consumption ◽  
Turbulence Model ◽  
Numerical Models ◽  
Sewage Treatment ◽  
Computational Cost ◽  
Primary Source ◽  
Pressure Head ◽  
Primary Objective ◽  
Pump Efficiency

A single-vaned centrifugal pump, typical of the kind employed in waste-water applications (e.g. sewage treatment), has been investigated numerically. The primary objective was to identify a modelling approach that was accurate, but at an acceptable computational cost. A test program has been executed to provide data to validate the numerical models. The global performance of the pump was assessed in terms of the pressure head, the mass flowrate, the power consumption, and the pump efficiency. In addition, time-resolved surface-pressure measurements were made at the volute wall. Five combinations of three modelling approximations (two or 3D; k-ε or Reynolds stress model turbulence model; unsteady or quasi-steady) were investigated and compared with the experimental results. It was found that the choice of turbulence model did not have a significant effect on the predictions. In all cases, the head-discharge curve was well predicted. However, it was found that only the quasi-steady models could capture the trend of the power consumption curve, and hence that of the efficiency. Discrepancies in the magnitude of the power consumption can be accounted for by the lack of losses such as leakage in the numerical models. Qualitative analysis of the numerical results identifies the trailing edge of the impeller as the primary source of power loss, with the flow in the region of the cut water also contributing significantly to the poor overall efficiency of the design.

Limits to optimization: fluid dynamics, adhesive strength and the evolution of shape in limpet shells

2000 ◽  
Vol 203 (17) ◽  
pp. 2603-2622 ◽  
Author(s):  
M.W. Denny
Keyword(s):  
Fluid Dynamics ◽  
Shell Height ◽  
Adhesive System ◽  
Hydrodynamic Forces ◽  
Optimal Shape ◽  
Shell Morphology ◽  
Rocky Shores ◽  
Adhesion System ◽  
Selection For ◽  
Lift And Drag

Limpets are commonly found on wave-swept rocky shores, where they may be subjected to water velocities in excess of 20 m s(−1). These extreme flows can impose large forces (lift and drag), challenging the animal's ability to adhere to the substratum. It is commonly thought that the conical shape of limpet shells has evolved in part to reduce these hydrodynamic forces while providing a large aperture for adhesion. This study documents how lift and drag actually vary with the shape of limpet-like models and uses these data to explore the potential of hydrodynamic forces to serve as a selective factor in the evolution of limpet shell morphology. At a low ratio of shell height to shell radius, lift is the dominant force, while at high ratios of height to radius drag is dominant. The risk of dislodgment is minimized when the ratio of height to radius is 1.06 and the apex is in the center of the shell. Real limpets are seldom optimally shaped, however, with a typical height-to-radius ratio of 0.68 and an apex well anterior of the shell's center. The disparity between the actual and the hydrodynamically optimal shape of shells may be due to the high tenacity of limpets' adhesive system. Most limpets adhere to the substratum so strongly that they are unlikely to be dislodged by lift or drag regardless of the shape of their shell. The evolution of a tenacious adhesion system (perhaps in response to predation) has thus preempted selection for a hydrodynamically optimal shell, allowing the shell to respond to alternative selective factors.

A Road Map for CFD Modelling of Forced Cooled Packages

2006 ◽  
Author(s):  
Emre O¨ztu¨rk ◽  
Ilker Tari
Keyword(s):  
Heat Transfer ◽  
Numerical Models ◽  
Turbulence Models ◽  
Thermal Design ◽  
Heat Sinks ◽  
Convergence Criteria ◽  
Cfd Modelling ◽  
Road Map ◽  
Discretization Schemes ◽  
Cfd Analyses

In this study, Computational Fluid Dynamics, which has taken its position in the thermal design of electronic packages, was used in order to draw a CFD road map for forced cooling conjugate heat transfer analyses in heat generating electronic systems. The main sources of error in CFD analyses arise from inappropriate numerical models including turbulence models, radiation modeling and discretization schemes, insufficient grid resolution, and lack of convergence. A complete computer chassis model with heat sinks and fans inside was created and parametric analyses were performed to compare the effects of different turbulence models, discretization schemes, mesh resolutions, convergence criteria, and radiative heat transfer. Two commercially available CFD software packages were used, Icepak™ for pre-processing, Fluent™ for solution and post-processing. The road map was applied to three different heat sinks modeled into the full chassis. Numerical results were compared with the available experimental data and they were in good agreement.

IMPROVED ALGORITHMS FOR LOW POWER MULTIPLEXOR DECOMPOSITION

2005 ◽  
Vol 14 (06) ◽  
pp. 1085-1099
Author(s):  
SHAOFA YANG ◽  
HON WAI LEONG
Keyword(s):  
Power Consumption ◽  
Low Power ◽  
Power Dissipation ◽  
Optimization Procedure ◽  
Decomposition Algorithm ◽  
Major Portion ◽  
Decomposition Problem ◽  
Reduce Power Consumption ◽  
Speed Up

It has been estimated that multiplexors (MUXes) make up a major portion of the circuitry in a typical chip. Therefore, to reduce power consumption of a chip, it is important to consider the design of MUXes that consumes less power. This is called the low power MUX decomposition problem and has been studied in Ref. 1. This paper improves on the results of Ref. 1 in two ways: (a) we propose a method to speed up the algorithms in Ref. 1, and (b) we propose a post-optimization procedure to further reduce the overall power dissipation of decompositions obtained by any MUX decomposition algorithm. Using this post-optimization procedure, we have been able to further reduce the power dissipation results of Ref. 1.

scholarly journals Experimental and Numerical Trimming Optimizations for a Mainsail in Upwind Conditions

2016 ◽  
Author(s):  
Matthieu Sacher ◽  
Frédéric Hauville ◽  
Régis Duvigneau ◽  
Olivier Le Maître ◽  
Nicolas Aubin ◽  
...  
Keyword(s):  
Numerical Model ◽  
Gaussian Process ◽  
Physical System ◽  
Numerical Models ◽  
Optimization Procedure ◽  
Performance Estimation ◽  
Direct Optimization ◽  
Structure Interaction ◽  
Two Parameters ◽  
Nonlinear Fluid

This paper investigates the use of meta-models for optimizing sails trimming. A Gaussian process is used to robustly approximate the dependence of the performance with the trimming parameters to be optimized. The Gaussian process construction uses a limited number of performance observations at carefully selected trimming points, potentially enabling the optimization of complex sail systems with multiple trimming parameters. We test the optimization procedure on the (two parameters) trimming of a scaled IMOCA mainsail in upwind conditions. To assess the robustness of the Gaussian process approach, in particular its sensitivity to error and noise in the performance estimation, we contrast the direct optimization of the physical system with the optimization of its numerical model. For the physical system, the optimization procedure was fed with wind tunnel measurements, while the numerical modeling relied on a fully nonlinear Fluid-Structure Interaction solver. The results show a correct agreement of the optimized trimming parameters for the physical and numerical models, despite the inherent errors in the numerical model and the measurement uncertainties. In addition, the number of performance estimations was found to be affordable and comparable in the two cases, demonstrating the effectiveness of the approach

Preliminary Design of Floating Point Absorber Offshore Rio de Janeiro

2015 ◽  
Author(s):  
Milad Shadman ◽  
Segen F. Estefen ◽  
Claudio Alexis Rodriguez Castillo ◽  
Marcelo I. Lourenço
Keyword(s):  
Rio De Janeiro ◽  
Reference Site ◽  
Numerical Models ◽  
Electrical Power ◽  
Optimization Procedure ◽  
Wave Climate ◽  
Floating Point ◽  
Concept Design ◽  
Climate Conditions ◽  
Point Absorber

The Rio floating point absorber (FPA) is designed for a reference site located near an island offshore Rio de Janeiro. According to the reference site characteristics, a two-body floating point absorber concept design is chosen to convert ocean wave energy into electrical power. An innovative procedure aiming at finding an optimal shape adapted to predefined wave climate conditions, using the Design of Experiments (DOE) method, is applied. A simple linear damper model is used to represent the Power Take-Off (PTO) mechanism. The optimization procedure is divided into Buoy and support (spar/plate) steps, so the optimized buoy is determined first and then a proper support is determined to reach a satisfactory two-body FPA system. The nonlinearities are not considered in this study and linear Numerical models are developed using AQWA/ANSYS and Minitab software in frequency domain. Finally, a preliminary optimized model of the two-body FPA is determined in accordance with the particular sea site information of the Rio de Janeiro.

scholarly journals Mechanical analyses on the digital behaviour of the Tokay gecko ( Gekko gecko ) based on a multi-level directional adhesion model

2015 ◽  
Vol 471 (2179) ◽  
pp. 20150085 ◽  
Author(s):  
Xuan Wu ◽  
Xiaojie Wang ◽  
Tao Mei ◽  
Shaoming Sun
Keyword(s):  
Angular Displacement ◽  
Adhesive System ◽  
Rigid Substrate ◽  
Gekko Gecko ◽  
Euler’S Elastica ◽  
Adhesion System ◽  
Tokay Gecko ◽  
Multi Level ◽  
Adhesion Model ◽  
Level Scale

This paper proposes a multi-level hierarchical model for the Tokay gecko ( Gekko gecko ) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko 's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko 's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid substrate, the directional adhesion behaviour of the seta has been investigated. The lamella-induced attachment and detachment have been modelled to simulate the active digital hyperextension (DH) and the digital gripping (DG) phenomena. The results suggest that a tiny angular displacement within 0.25° of the lamellar proximal end is necessary in which a fast transition from attachment to detachment or vice versa is induced. The active DH helps release the torque to induce setal non-sliding detachment, while the DG helps apply torque to make the setal adhesion stable. The lamella plays a key role in saving energy during detachment to adapt to its habitat and provides another adhesive function which differs from the friction-dependent setal adhesion system controlled by the dynamic of G. gecko 's body.

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