Aeromechanics of passive rotation in flapping flight

2010 ◽  
Vol 660 ◽  
pp. 197-220 ◽  
Author(s):  
J. P. WHITNEY ◽  
R. J. WOOD
Keyword(s):  
Aerodynamic Force ◽  
Equations Of Motion ◽  
Beat Frequency ◽  
Element Model ◽  
Rotational Dynamics ◽  
Model Parameters ◽  
Passive Rotation ◽  
Out Of Plane ◽  
Three Degree Of Freedom ◽  
Blade Element

Flying insects and robots that mimic them flap and rotate (or ‘pitch’) their wings with large angular amplitudes. The reciprocating nature of flapping requires rotation of the wing at the end of each stroke. Insects or flapping-wing robots could achieve this by directly exerting moments about the axis of rotation using auxiliary muscles or actuators. However, completely passive rotational dynamics might be preferred for efficiency purposes, or, in the case of a robot, decreased mechanical complexity and reduced system mass. Herein, the detailed equations of motion are derived for wing rotational dynamics, and a blade-element model is used to supply aerodynamic force and moment estimates. Passive-rotation flapping experiments with insect-scale mechanically driven artificial wings are conducted to simultaneously measure aerodynamic forces and three-degree-of-freedom kinematics (flapping, rotation and out-of-plane deviation), allowing a detailed evaluation of the blade-element model and the derived equations of motion. Variations in flapping kinematics, wing-beat frequency, stroke amplitude and torsional compliance are made to test the generality of the model. All experiments showed strong agreement with predicted forces and kinematics, without variation or fitting of model parameters.

Energy harvesting from aeroelastic vibrations induced by discrete gust loads

2016 ◽  
Vol 28 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Claudia Bruni ◽  
James Gibert ◽  
Giacomo Frulla ◽  
Enrico Cestino ◽  
Pier Marzocca
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Flow Region ◽  
Rotational Displacement ◽  
Reduced Order ◽  
Piezoelectric Elements ◽  
Out Of Plane ◽  
Gust Loads ◽  
Three Degree Of Freedom ◽  
Euler Bernoulli Beam

This article evaluates the amount of energy that can be extracted from a gust using an aeroelastic energy harvester composed of a flexible wing with attached piezoelectric elements. The harvester operates in a subcritical flow region. It is modeled as a linear Euler–Bernoulli beam sandwiched between two piezoceramics. The extended Hamilton’s principle is used to derive the harvester’s equations of motion and an eigenfunction expansion is used to form a three-degree-of-freedom reduced-order model. The degrees of freedom retained in the model are two flexural degrees for the in-plane and out-of-plane displacements, and a torsional degree for the rotational displacement. Wagner and Küssner functions are used to represent the unsteady aerodynamic and gust loading, respectively. The amount of energy extracted from the system is then compared for two different deterministic gust profiles, 1-COSINE and two sharp-edged gusts forming a square gust, for various magnitudes and durations. The results show that the harvester is able to extract more energy from the square gust profile, although for both profiles the harvester extracts more power after the gust has subsided.

scholarly journals A semi-empirical model of the aerodynamics of manoeuvring insect flight

2020 ◽  
Author(s):  
Simon M. Walker ◽  
Graham K. Taylor
Keyword(s):  
Sagittal Plane ◽  
Insect Flight ◽  
Aerodynamic Force ◽  
Three Dimensional ◽  
Element Model ◽  
Parameter Estimates ◽  
Free Flight ◽  
Kinematic Data ◽  
Semi Empirical ◽  
Blade Element

Blade element modelling provides a quick analytical method for estimating the aerodynamic forces produced during insect flight, but such models have yet to be tested rigorously using kinematic data recorded from free-flying insects. This is largely because of the paucity of detailed free-flight kinematic data, but also because analytical limitations in existing blade element models mean that they cannot incorporate the complex three-dimensional movements of the wings and body that occur during insect flight. Here, we present a blade element model with empirically-fitted aerodynamic force coefficients that incorporates the full three-dimensional wing kinematics of manoeuvring Eristalis hoverflies, including torsional deformation of their wings. The two free parameters were fitted to a large free-flight dataset comprising N = 26, 541 wingbeats, and the fitted model captured approximately 80% of the variation in the stroke-averaged forces in the sagittal plane. We tested the robustness of the model by subsampling the data, and found little variation in the parameter estimates across subsamples comprising 10% of the flight sequences. The simplicity and generality of the model that we present is such that it can be readily applied to kinematic datasets from other insects, and also used for the study of insect flight dynamics.

scholarly journals A semi-empirical model of the aerodynamics of manoeuvring insect flight

2021 ◽  
Vol 18 (177) ◽  
Author(s):  
Simon M. Walker ◽  
Graham K. Taylor
Keyword(s):  
Sagittal Plane ◽  
Insect Flight ◽  
Aerodynamic Force ◽  
Three Dimensional ◽  
Element Model ◽  
Parameter Estimates ◽  
Free Flight ◽  
Kinematic Data ◽  
Semi Empirical ◽  
Blade Element

Blade element modelling provides a quick analytical method for estimating the aerodynamic forces produced during insect flight, but such models have yet to be tested rigorously using kinematic data recorded from free-flying insects. This is largely because of the paucity of detailed free-flight kinematic data, but also because analytical limitations in existing blade element models mean that they cannot incorporate the complex three-dimensional movements of the wings and body that occur during insect flight. Here, we present a blade element model with empirically fitted aerodynamic force coefficients that incorporates the full three-dimensional wing kinematics of manoeuvring Eristalis hoverflies, including torsional deformation of their wings. The two free parameters were fitted to a large free-flight dataset comprising N = 26 541 wingbeats, and the fitted model captured approximately 80% of the variation in the stroke-averaged forces in the sagittal plane. We tested the robustness of the model by subsampling the data, and found little variation in the parameter estimates across subsamples comprising 10% of the flight sequences. The simplicity and generality of the model that we present is such that it can be readily applied to kinematic datasets from other insects, and also used for the study of insect flight dynamics.

Understanding Tire Dynamic Characteristics for Vehicle Dynamics Ride Using Simulation Methods

2019 ◽  
Vol 48 (3) ◽  
pp. 188-206
Author(s):  
Yaswanth Siramdasu ◽  
Kejing Li ◽  
Robert Wheeler
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Element Model ◽  
Design Parameters ◽  
Model Parameters ◽  
Ring Model ◽  
Design Changes ◽  
Parameter Variations ◽  
Tire Dynamics ◽  
Three Degree Of Freedom

ABSTRACT The dynamic characteristics of a tire are studied by simulating its rolling over a cleat and observing the effect on in-plane rigid belt vibration modes. Three modeling approaches are used to understand various tire design parameters affecting the tire dynamics relevant for vehicle ride performance. First, a simplified three-degree-of-freedom rigid ring model is used for fundamental understanding of these modes. Next, a detailed finite element model accounting for component compliances is used for studying the sensitivity of the modes to most common design parameter variations employed in tire development. Finally, to study these tire design changes in operation, vehicle simulations using CarSim and FTire models are performed. FTire model parameters corresponding to tire design parameters are adjusted accordingly. Observations are reported of the effects of tire design parameters on cleat responses and on correlation of results between finite element and FTire models.

Model of vortex flow of charge in a vessel with turbine impeller

1987 ◽  
Vol 52 (8) ◽  
pp. 1888-1904
Author(s):  
Miloslav Hošťálek ◽  
Ivan Fořt
Keyword(s):  
Boundary Conditions ◽  
Equations Of Motion ◽  
Theoretical Data ◽  
Eddy Diffusion ◽  
Quantitative Agreement ◽  
Creeping Flow ◽  
Model Parameters ◽  
Mean Flow ◽  
Two Dimensional Flow ◽  
Vorticity Transport

A theoretical model is described of the mean two-dimensional flow of homogeneous charge in a flat-bottomed cylindrical tank with radial baffles and six-blade turbine disc impeller. The model starts from the concept of vorticity transport in the bulk of vortex liquid flow through the mechanism of eddy diffusion characterized by a constant value of turbulent (eddy) viscosity. The result of solution of the equation which is analogous to the Stokes simplification of equations of motion for creeping flow is the description of field of the stream function and of the axial and radial velocity components of mean flow in the whole charge. The results of modelling are compared with the experimental and theoretical data published by different authors, a good qualitative and quantitative agreement being stated. Advantage of the model proposed is a very simple schematization of the system volume necessary to introduce the boundary conditions (only the parts above the impeller plane of symmetry and below it are distinguished), the explicit character of the model with respect to the model parameters (model lucidity, low demands on the capacity of computer), and, in the end, the possibility to modify the given model by changing boundary conditions even for another agitating set-up with radially-axial character of flow.

On Robe’s restricted problem with a modified Newtonian potential

2020 ◽  
Vol 18 (01) ◽  
pp. 2150005 ◽  
Author(s):  
Elbaz I. Abouelmagd ◽  
Abdullah A. Ansari ◽  
M. H. Shehata
Keyword(s):  
Equilibrium Points ◽  
Equations Of Motion ◽  
Underwater Vehicles ◽  
Newtonian Potential ◽  
Second Primary ◽  
The Moon ◽  
Primary Body ◽  
Out Of Plane ◽  
Robe’S Restricted Problem ◽  
Dust Grain

We analyze the existence of equilibrium points for a particle or dust grain in the framework of unperturbed and perturbed Robe’s motion. This particle is moving in a spherical nebula consisting of a homogeneous incompressible fluid, which is considered as the primary body. The second primary body creates the modified Newtonian potential. The perturbed mean motion and equations of motion are found. The equilibrium points (i.e. collinear, noncollinear and out–of–plane points), along with the required conditions of their existence are also analyzed. We emphasize that this analysis can be used to study the oscillations of the Earth’s core under the attraction of the Moon and it is also applicable to study the motion of underwater vehicles.

Studies on Galloping of Iced Conductor Based on Tower-Line Coupling System – Aerodynamic Loads

2012 ◽  
Vol 182-183 ◽  
pp. 1630-1633
Author(s):  
Hao Jun Hu ◽  
Yuan Han Wang ◽  
Zi Dong Hu
Keyword(s):  
Finite Element ◽  
Wind Speed ◽  
Finite Element Model ◽  
Aerodynamic Force ◽  
Element Model ◽  
Aerodynamic Characteristics ◽  
Explicit Integration ◽  
Computing Platform ◽  
Coupling System ◽  
Line Coupling

Based on the second development at the ANSYS computing platform, finite element model of a Tower-Line Coupling system was established. The computational fluid dynamics module (CFX) was used for the numerical simulation of the aerodynamic characteristics of iced conductor. On the basis of the Kaimal spectrum, fast Fourier transform was introduced to prepare the wind speed simulation program WVFS with spatial correlation into consideration, thus generating aerodynamic coefficients of iced conductor at different wind attack angles as well as wind speed time series at tower-line nodes. According to the finite element model of continuous multi-conductors and the aerodynamic force- wind attack angle curve, the explicit integration is applied for numerical solution of galloping of iced conductor.

scholarly journals Rotational Dynamics of Optically Trapped Human Spermatozoa

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Elavarasan Subramani ◽  
Himanish Basu ◽  
Shyam Thangaraju ◽  
Sucheta Dandekar ◽  
Deepak Mathur ◽  
...  
Keyword(s):  
Near Infrared ◽  
Beat Frequency ◽  
Translational Motion ◽  
Rotational Dynamics ◽  
Sperm Cells ◽  
Integrated Optical ◽  
Fertility Potential ◽  
Live Sperm ◽  
Fertilization Capacity ◽  
Optically Trapped

Introduction. Optical trapping is a laser-based method for probing the physiological and mechanical properties of cells in a noninvasive manner. As sperm motility is an important criterion for assessing the male fertility potential, this technique is used to study sperm cell motility behavior and rotational dynamics.Methods and Patients. An integrated optical system with near-infrared laser beam has been used to analyze rotational dynamics of live sperm cells from oligozoospermic and asthenozoospermic cases and compared with controls.Results. The linear, translational motion of the sperm is converted into rotational motion on being optically trapped, without causing any adverse effect on spermatozoa. The rotational speed of sperm cells from infertile men is observed to be significantly less as compared to controls.Conclusions. Distinguishing normal and abnormal sperm cells on the basis of beat frequency above 5.6 Hz may be an important step in modern reproductive biology to sort and select good quality spermatozoa. The application of laser-assisted technique in biology has the potential to be a valuable tool for assessment of sperm fertilization capacity for improving assisted reproductive technology.

GPR-based novel approach for non-linear aerodynamic modelling from flight data

2018 ◽  
Vol 123 (1259) ◽  
pp. 79-92
Author(s):  
A. Kumar ◽  
A. K. Ghosh
Keyword(s):  
Aerodynamic Force ◽  
Equations Of Motion ◽  
Gaussian Process Regression ◽  
Likelihood Estimation ◽  
Flight Data ◽  
Novel Approach ◽  
Non Linear ◽  
Research Aircraft ◽  
Novel Method ◽  
Aerodynamic Modelling

ABSTRACTIn this paper, a Gaussian process regression (GPR)-based novel method is proposed for non-linear aerodynamic modelling of the aircraft using flight data. This data-driven regression approach uses the kernel-based probabilistic model to predict the non-linearity. The efficacy of this method is examined and validated by estimating force and moment coefficients using research aircraft flight data. Estimated coefficients of aerodynamic force and moment using GPR method are compared with the estimated coefficients using maximum-likelihood estimation (MLE) method. Estimated coefficients from the GPR method are statistically analysed and found to be at par with estimated coefficients from MLE, which is popularly used as a conventional method. GPR approach does not require to solve the complex equations of motion. GPR further can be directed for the generalised applications in the area of aeroelasticity, load estimation, and optimisation.

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