Dynamics of a Radial Electrorheological Clutch

1999 ◽  
Vol 13 (14n16) ◽  
pp. 2119-2126 ◽  
Author(s):  
M. Whittle ◽  
R. J. Atkin ◽  
W. A. Bullough
Keyword(s):  
Yield Stress ◽  
High Speed ◽  
Fluid Dynamic ◽  
Equations Of Motion ◽  
Time Dependent ◽  
Maximum Acceleration ◽  
Bingham Plastic ◽  
Viscous Component ◽  
Output Load ◽  
Dynamic Restriction

Time dependent solutions to the equations of motion for flow in an enclosed radial electro-rheological clutch are developed and discussed in relation to the speed of operation. The method follows a procedure previously developed for cylindrical clutch geometry but in this case analytical solutions are obtained. The fluid is treated as a homogeneous continuum obeying the Bingham plastic constitutive equation incorporating a yield stress and viscous component. The results show that the acceleration expected from a consideration of yield stress and inertia is not always achieved. The viscous component places fluid dynamic restriction on the maximum acceleration of the output rotor. However, this limit is only approached if the output load inertia is very low. The results have a bearing on the choice of fluid for high speed operation.

Dynamics of an Electrorheological Valve

1996 ◽  
Vol 10 (23n24) ◽  
pp. 2933-2950 ◽  
Author(s):  
M. Whittle ◽  
R.J. Atkin ◽  
W.A. Bullough
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Equations Of Motion ◽  
Plastic Viscosity ◽  
Time Dependent ◽  
Electrode Gap ◽  
Bingham Plastic ◽  
Speed Of Response ◽  
Viscous Component

Time dependent solutions to the equations of motion for flow in an electro-rheological valve are developed and discussed in relation to the limiting speed of operation. The fluid is considered to be a homogeneous continuum obeying the Bingham plastic constitutive equation incorporating a yield stress and viscous component. The results show that the speed of response is determined principally by the plastic viscosity and electrode gap irrespective of the yield stress and corroborates earlier work.

Propagation of acoustic pulses in some fluids with yield stress

2011 ◽  
Vol 89 (2) ◽  
pp. 219-224
Author(s):  
Anna Perelomova
Keyword(s):  
Yield Stress ◽  
Apparent Viscosity ◽  
Acoustic Pulse ◽  
Time Dependent ◽  
Unusual Property ◽  
Leading Order ◽  
Bingham Plastic ◽  
Small Parameters ◽  
Thixotropic Fluid ◽  
Approximate Equations

This study is devoted to the derivation of approximate equations governing acoustic pulses in flows with yield stress, including some time-dependent flows with a slow dependence on time of yield stress and apparent viscosity. The modeling of yield stress and apparent viscosity in the vicinity of a zero deformation rate allows us to consider a thixotropic fluid as a Bingham plastic with coefficients that are dependent on time. The ordering scheme results in equations that are valid in leading order with respect to a number of small parameters. The unusual property of the domains of a waveform with positive and negative shear stress to propagate with different velocities is discovered. The illustration concerns the initially bipolar acoustic pulse, which becomes positive after some time. The proposed theory predicts broadening of a pulse due to the yield stress, starting at some time after the beginning of its evolution.

Time-Dependent Solution of Unsteady Fluid Flow Equations for High Speed Oscillating Compressible Flows and Blast Wave Propagations

2020 ◽  
Author(s):  
Ramlala P. Sinha
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Blast Wave ◽  
High Speed ◽  
Fluid Dynamic ◽  
Time Dependent ◽  
Arbitrary Boundary ◽  
One Dimensional ◽  
Unsteady Fluid ◽  
Energy Equations

Abstract A solution of the highly complex unsteady high speed oscillating compressible flow field inside a cylindrical tube has been obtained numerically, assuming one dimensional, viscous, and heat conducting flow, by solving the appropriate fluid dynamic and energy equations. The tube is approximated by a right circular cylinder closed at one end with a piston oscillating at very high resonant frequency at the other end. An iterative implicit finite difference scheme is employed to obtain the solution. The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties. The solution would also be valid for tapered tubes if the variations in the cross-sectional area are small. In successfully predicting the time dependent results, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems. The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid-structure interaction heat transfer enhancement, and fluidic pyrotechnic initiation devices. It can further be easily extended to cover muzzle blasts and nuclear explosion blast wave propagations in one dimensional and/or radial spherical coordinates with or without including energy generation / addition terms.

Shock Wave and Flow Velocity Measurements in a High Speed Fan Rotor Using the Laser Velocimeter

1977 ◽  
Vol 99 (2) ◽  
pp. 181-187 ◽  
Author(s):  
D. C. Wisler
Keyword(s):  
Shock Wave ◽  
Flow Velocity ◽  
High Speed ◽  
Fluid Dynamic ◽  
Equations Of Motion ◽  
Seed Particle ◽  
Gas Velocity ◽  
Velocity Measurements ◽  
Rotating Blade ◽  
Finite Difference Solution

The laser velocimeter, an instrument capable of making nondisturbing gas velocity measurements, was used to determine shock wave locations and to make gas velocity measurements within the rotating blade row of a 550-m/s (1800-ft/s)-tip speed fan rotor. The velocimeter measures the transit time of a seed particle across interference fringes produced at the intersection of a split and crossed laser beam. The rotor flowfields were obtained at several radial immersions for operating-line and near-stall throttle settings. The results show the change in shock pattern and flow velocity as the compressor is throttled toward stall. Analytical predictions of the flowfield were also obtained using both the method of characteristics and a time-dependent, finite-difference solution of the fluid dynamic equations of motion. The analytical results and the flowfield measurements are considered to be in good agreement.

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

Dynamic characteristics of a drill in the drilling process

2003 ◽  
Vol 217 (2) ◽  
pp. 161-167 ◽  
Author(s):  
B W Huang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Thrust Force ◽  
Time Dependent ◽  
Drilling Process ◽  
Improve Quality ◽  
Vibration Model ◽  
High Speed Drilling ◽  
Spinning Speed ◽  
Twisted Beam

The dynamic characteristics of high-speed drilling were investigated in this study. To improve quality and produce a higher production rate, the dynamic characteristics of the drilling process need to be studied. A pre-twisted beam is used to simulate the drill. The moving Winkler-type elastic foundation is used to approximate the drilling process. A time-dependent vibration model for drilling is presented. The spinning speed, pre-twisted angle and thrust force effects of the drill are considered. The numerical analysis indicates that the natural frequency is suddenly reduced as the drill moves into a workpiece.

Kinematics of Tongue Projection in Chamaeleo Oustaleti

1991 ◽  
Vol 159 (1) ◽  
pp. 109-133 ◽  
Author(s):  
PETER C. WAINWRIGHT ◽  
DAVID M. KRAKLAU ◽  
ALBERT F. BENNETT
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Maximum Velocity ◽  
Head Movements ◽  
Florida State University ◽  
State University ◽  
Maximum Acceleration ◽  
Related Family ◽  
High Speed Cinematography ◽  
Tongue Movements

The kinematics of prey capture by the chamaeleonid lizard Chamaeleo oustaleti were studied using high-speed cinematography. Three feeding sequences from each of two individuals were analyzed for strike distances of 20 and 35 cm, at 30°C. Ten distances and angles were measured from sequential frames beginning approximately 0.5 s prior to tongue projection and continuing for about 1.0 s. Sixteen additional variables, documenting maximum excursions and the timing of events, were calculated from the kinematic profiles. Quantified descriptions of head, hyoid and tongue movements are presented. Previously unrecognized rapid protraction of the hyobranchial skeleton simultaneously with the onset of tongue projection was documented and it is proposed that this assists the accelerator muscle in powering tongue projection. Acceleration of the tongue occurred in about 20ms, reaching a maximum acceleration of 486 m s−2 and maximum velocity of 5.8m s−1 in 35 cm strikes. Deceleration of the tongue usually began within 5 ms before prey contract and the direction of tongue movement was reversed within 10 ms of prey contact. Retraction of the tongue, caused by shortening of the retractor muscles, reached a maximum velocity of 2.99 ms−1 and was complete 330 ms after prey contact. Projection distance influences many aspects of prey capture kinematics, particularly projection time, tongue retraction time and the extent of gape and head movements during tongue retraction, all of which are smaller in shorter feedings. Though several features of the chameleon strike have apparently been retained from lizards not capable of ballistic tongue projection, key differences are documented. Unlike members of a related family, the Agamidae, C. oustaleti uses no body lunge during prey capture, exhibits gape reduction during tongue projection and strongly depresses the head and jaws during tongue retraction. Note: Present address: Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA.

Comparison of the fast-start performances of closely related, morphologically distinct threespine sticklebacks (Gasterosteus spp.)

1996 ◽  
Vol 199 (12) ◽  
pp. 2595-2604 ◽  
Author(s):  
T Law ◽  
R Blake
Keyword(s):  
Angular Velocity ◽  
High Speed ◽  
High Performance ◽  
Gasterosteus Aculeatus ◽  
Morphological Characteristics ◽  
Maximum Velocity ◽  
Threespine Stickleback ◽  
Biomechanical Study ◽  
Maximum Acceleration ◽  
Fast Start

Fast-start escape performances for two species of threespine stickleback, Gasterosteus spp., were investigated using high-speed cinematography (400 Hz). The two fishes (not yet formally described, referred to here as benthic and limnetic) inhabit different niches within Paxton Lake, British Columbia, Canada, and are recent, morphologically distinct species. All escape responses observed for both species were double-bend C-type fast-starts. There were no significant differences between the species for any linear or angular parameter (pooled averages, both species: duration 0.048 s, distance 0.033 m, maximum velocity 1.10 m s-1, maximum acceleration 137 m s-2, maximum horizontal angular velocity 473.6 rad s-1 and maximum overall angular velocity 511.1 rad s-1). Benthics and limnetics have the greatest added mass (Ma) at 0.3 and 0.6 body lengths, respectively. The maximum Ma does not include the fins for benthics, but for limnetics the dorsal and anal fins contribute greatly to the maximum Ma. The deep, posteriorly placed fins of limnetics enable them to have a fast-start performance equivalent to that of the deeper-bodied benthics. Both the limnetic and benthic fishes have significantly higher escape fast-start velocities than their ancestral form, the anadromous threespine stickleback Gasterosteus aculeatus, suggesting that the high performance of the Paxton Lake sticklebacks is an evolutionarily derived trait. In this biomechanical study of functional morphology, we demonstrate that similar high fast-start performance can be achieved by different suites of morphological characteristics and suggest that predation might be the selective force for the high escape performance in these two fishes.

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