Passive control of aerodynamically forced vibrations of supersonic turbomachine rotors by splitter blades

1986 ◽  
Author(s):  
S. FLEETER ◽  
D. TOPP ◽  
D. HOYNIAK
Keyword(s):  
Passive Control ◽  
Forced Vibrations

scholarly journals Dynamical Analysis Applied to Passive Control of Vibrations in a Structural Model Incorporating SMA-SE Coil Springs

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Yuri J. O. Moraes ◽  
Antonio A. Silva ◽  
Marcelo C. Rodrigues ◽  
Antonio G. B. de Lima ◽  
Rômulo P. B. dos Reis ◽  
...  
Keyword(s):  
Smart Materials ◽  
Passive Control ◽  
Structural Model ◽  
Physical World ◽  
Forced Vibrations ◽  
Dynamical Analysis ◽  
Modal Shape ◽  
Irreversible Damage ◽  
Second Mode ◽  
Structure Configuration

Mechanical vibrations are severe phenomena of the physical world. These oscillations may become undesirable and may cause temporary and even irreversible damage to the system. There are several techniques to minimizing these vibration effects ranging from passive methods to the use of controllers with smart materials. In this sense, this study aims to analyze a passive vibration control system installed in a structure that simulates two-floor buildings. This system based on the incorporation of one SMA-SE (Superelastic Shape Memory Alloys) coil springs configuration for energy dissipation and the addition of damping. Modal analysis was performed using analytical, numerical, and experimental methods. In an experimental basis, response amplitudes were analyzed for free and forced vibrations in different configurations. As compared with the structure configuration with steel spring, the forced vibrations FRF (Frequency Response Function) analysis showed a reduction in displacement transmissibility of up to 51% for the first modal shape and 73% for the second mode in the SMA-SE coil spring configuration. As for damping, there was a considerable increase in the order of 59% in the first mode and 119% in the second, for the SMA-SE springs configuration.

Passive Control of a Hydraulic Valve

1989 ◽  
Author(s):  
John D. Charlton ◽  
James J. Brickley
Keyword(s):  
Passive Control ◽  
Hydraulic Valve

UNCERTAINTIES ON ADHESIVE LAYER FOR A PLATE STRUCTURE: PASSIVE CONTROL

2019 ◽  
Author(s):  
Guilherme Silva Prado ◽  
Heinsten Frederich Leal dos Santos
Keyword(s):  
Passive Control ◽  
Adhesive Layer ◽  
Plate Structure

Chemical Permeation Enhancers for Transdermal Delivery of Thiocolchicoside: Assessment of Ex-vivo Skin Flux and In-vivo Pharmacokinetics

2017 ◽  
Vol 10 (5) ◽  
pp. 3827-3835
Author(s):  
Y Madhusudan Rao ◽  
Gayatri P ◽  
Ajitha M ◽  
P. Pavan Kumar ◽  
Kiran kumar
Keyword(s):  
Passive Control ◽  
Ex Vivo ◽  
Skin Permeation ◽  
In Vivo Studies ◽  
Permeation Enhancers ◽  
Casting Technique ◽  
Chemical Permeation Enhancers ◽  
Chemical Permeation ◽  
In Vivo Pharmacokinetics

Present investigation comprises the study of ex-vivo skin flux and in-vivo pharmacokinetics of Thiocolchicoside (THC) from transdermal films. The films were fabricated by solvent casting technique employing combination of hydrophilic and hydrophobic polymers. A flux of 18.08 µg/cm2h and 13.37µg/cm2h was achieved for optimized formulations containing 1, 8-cineole and oleic acid respectively as permeation enhancers. The observed flux values were higher when compared to passive control (8.66 µg/cm2h). Highest skin permeation was observed when 1,8-cineole was used as chemical permeation enhancer and it considerably (2-2.5 fold) improved the THC transport across the rat skin. In vivo studies were performed in rabbits and samples were analysed by LC-MS-MS. The mean area under the curve (AUC) values of transdermal film showed about 2.35 times statistically significant (p<0.05) improvement in bioavailability when compared with the oral administration of THC solution. The developed transdermal therapeutic systems using chemical permeation enhancers were suitable for drugs like THC in effective management of muscular pain.    

Disorganization of a hole tone feedback loop by an axisymmetric obstacle on a downstream end plate

2014 ◽  
Vol 757 ◽  
pp. 908-942 ◽  
Author(s):  
K. Matsuura ◽  
M. Nakano
Keyword(s):  
Nozzle Exit ◽  
Passive Control ◽  
Control Method ◽  
Three Dimensional ◽  
Acoustic Power ◽  
Shear Layers ◽  
Mean Velocity ◽  
End Plate ◽  
Air Jet ◽  
Practical Engineering

AbstractThis study investigates the suppression of the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. The mean velocity of the air jet $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}u_0$ was $6\text {--}12\ \mathrm{m}\ {\mathrm{s}}^{-1}$. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length $L_{im}$ between the nozzle and the end plate was 50–90 mm. We propose a novel passive control method of suppressing the tone with an axisymmetric obstacle on the end plate. We find that the effect of the obstacle is well described by the combination ($W/L_{im}$, $h$) where $W$ is the distance from the edge of the end plate hole to the inner wall of the obstacle, and $h$ is the obstacle height. The tone is suppressed when backflows from the obstacle affect the jet shear layers near the nozzle exit. We do a direct sound computation for a typical case where the tone is successfully suppressed. Axisymmetric uniformity observed in the uncontrolled case is broken almost completely in the controlled case. The destruction is maintained by the process in which three-dimensional vortices in the jet shear layers convect downstream, interact with the obstacle and recursively disturb the jet flow from the nozzle exit. While regions near the edge of the end plate hole are responsible for producing the sound in the controlled case as well as in the uncontrolled case, acoustic power in the controlled case is much lower than in the uncontrolled case because of the disorganized state.

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