Introductory PZT Actuators Optimal Working Configuration Experimental Study in a Turbofan Engine Fan Rotor Blade

2020 ◽  
Author(s):  
Fabio Botta ◽  
Andrea Rossi
Keyword(s):  
Rotor Blade ◽  
Vibration Suppression ◽  
Resonant Mode ◽  
Turbofan Engine ◽  
Active Systems ◽  
Rotating Blade ◽  
Modal Damping ◽  
Resonant Modes ◽  
Turbomachinery Blades ◽  
External Forces

Abstract Vibration suppression systems are often crucial to extend the life cycle of the structures in several engineering fields. The passive systems are the most commonly used but, in case of dynamic loads, the active systems show a greater efficiency. Since the external forces acting on a rotating blade may excite several vibrational modes simultaneously, an active multi-modal damping device could enhance the damping action. The piezoelectric (PZT) actuators seem to be the most promising but their placing on the structure plays a crucial role. In this paper, some PZT actuators have been mounted on the surface of an actual rotor blade from the second fan stage of a turbofan engine and their working configuration has been optimized on the basis of a previously developed model. Thereby, the actuators are able to efficiently damp the most detrimental resonant mode or a resonant modes coupling. The experimental results show that the proposed system well suits the application and may be considered as an alternative method to deal with vibration issues in turbomachinery blades.

Robust Vibration Suppression of Resonant Modes by Feedback Compensation Realized Using Allpass Filters

2009 ◽  
Vol 129 (10) ◽  
pp. 981-988 ◽  
Author(s):  
Noriaki Hirose ◽  
Makoto Iwasaki ◽  
Motohiro Kawafuku ◽  
Hiromu Hirai
Keyword(s):  
Vibration Suppression ◽  
Allpass Filters ◽  
Resonant Modes ◽  
Feedback Compensation

scholarly journals Graph-facilitated resonant mode counting in stochastic interaction networks

2017 ◽  
Vol 14 (137) ◽  
pp. 20170447 ◽  
Author(s):  
Michael F. Adamer ◽  
Thomas E. Woolley ◽  
Heather A. Harrington
Keyword(s):  
Dynamical Systems ◽  
Applied Mathematics ◽  
Direct Calculation ◽  
Resonant Mode ◽  
Interaction Networks ◽  
Deterministic System ◽  
Stochastic Dynamical Systems ◽  
Graph Theoretic ◽  
Resonant Modes ◽  
Parameter Ranges

Oscillations in dynamical systems are widely reported in multiple branches of applied mathematics. Critically, even a non-oscillatory deterministic system can produce cyclic trajectories when it is in a low copy number, stochastic regime. Common methods of finding parameter ranges for stochastically driven resonances, such as direct calculation, are cumbersome for any but the smallest networks. In this paper, we provide a systematic framework to efficiently determine the number of resonant modes and parameter ranges for stochastic oscillations relying on real root counting algorithms and graph theoretic methods. We argue that stochastic resonance is a network property by showing that resonant modes only depend on the squared Jacobian matrix J 2 , unlike deterministic oscillations which are determined by J . By using graph theoretic tools, analysis of stochastic behaviour for larger interaction networks is simplified and stochastic dynamical systems with multiple resonant modes can be identified easily.

scholarly journals Compact Ultra-Wideband Bandpass Filters Achieved by Using a Stub-Loaded Stepped Impedance Resonator

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 209 ◽  
Author(s):  
Min-Hang Weng ◽  
Fu-Zhong Zheng ◽  
Hong-Zheng Lai ◽  
Shih-Kun Liu
Keyword(s):  
Resonant Mode ◽  
Bandpass Filters ◽  
Ultra Wideband ◽  
Design Parameters ◽  
Transmission Zeros ◽  
Notch Band ◽  
Resonant Modes ◽  
Attenuation Level ◽  
Stepped Impedance Resonator ◽  
5 Ghz

In this paper, we develop a bandpass filter using a stub-loaded stepped impedance resonator (SLSIR) and calculate the even and odd resonant modes of this type of resonator using the input impedance/admittance analysis. In this study, two impedance ratios and two length ratios are operated as the design parameters for controlling the resonant modes of the SLSIR. Several resonant mode variation curves operating three resonant modes with different impedance ratios and two length ratios are developed. By tuning the desired impedance ratios and length ratios of the SLSIRs, compact ultra-wideband (UWB) bandpass filters (BPFs) can be achieved. Two examples of the UWB BPFs are designed in this study. The first example is UWB filter with a wide stopband and the second one is dual UWB BPF, namely, with UWB performance and a notch band. The first filter is designed for a UWB response from 3.1 to 5.26 GHz having a stopband from 5.3 to 11 GHz, with an attenuation level better than 18 dB. The second filter example is a dual UWB BPF with the frequency range from 3.1 to 5 GHz and 6 to 10.1 GHz using two sets of the proposed SLSIR. The measured results have insertion loss of less than 1 dB, and return loss greater than 10 dB. Furthermore, the coupling structures and open stub of the SLSIR also provide several transmission zeros at the skirt of the passbands for improving the passband selectivity.

Blades Forced Vibration Under Aero-Elastic Excitation Modeled by Van der Pol

2017 ◽  
Vol 27 (11) ◽  
pp. 1750166 ◽  
Author(s):  
Ladislav Pust ◽  
Ludek Pesek
Keyword(s):  
Rotor Blade ◽  
Analytical Approach ◽  
Nonlinear Models ◽  
Dynamic Properties ◽  
Deformation Wave ◽  
Response Curves ◽  
Van Der Pol ◽  
External Forces ◽  
Real Type

This paper employs a new analytical approach to model the influence of aerodynamic excitation on the dynamics of a bladed cascade at the flutter state. The flutter is an aero-elastic phenomenon that is linked to the interaction of the flow and the traveling deformation wave in the cascade when only the damping of the cascade changes. As a case study the dynamic properties of the five-blade-bunch excited by the running harmonic external forces and aerodynamic self-excited forces are investigated. This blade-bunch is linked in the shroud by means of the viscous-elastic damping elements. The external running excitation depends on the ratio of stator and rotor blade numbers and corresponds to the real type of excitation in the steam turbine. The aerodynamic self-excited forces are modeled by two types of Van der Pol nonlinear models. The influence of the interaction of both types of self-excitation with the external running excitation is investigated on the response curves.

scholarly journals Frequency Tuning of a Disk Resonator Gyro Via Mass Matrix Perturbation

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
David Schwartz ◽  
Dong Joon Kim ◽  
Robert T. M’Closkey
Keyword(s):  
High Performance ◽  
Frequency Tuning ◽  
Perturbation Technique ◽  
Mass Matrix ◽  
Resonant Mode ◽  
Matrix Perturbation ◽  
Operating Environment ◽  
Vibratory Gyroscopes ◽  
Resonant Modes ◽  
The Stability

Electrostatic tuning of the resonant modes in microelectromechanical vibratory gyroscopes is often suggested as a means for compensating manufacturing aberrations that produce detuned resonances. In high performance sensors, however, this approach places very stringent requirements on the stability of the bias voltages used for tuning. Furthermore, the bias voltage stability must be maintained over the operating environment, especially with regard to temperature variations. An alternative solution to this problem is to use mass perturbations of the sensor’s resonant structure for resonant mode tuning. This paper presents a new mass perturbation technique that only relies on the sensor’s integrated actuators and pick-offs to guide the mass perturbation process. The algorithm is amenable to automation and eliminates the requirement that the modal nodes of the resonator be identified by direct measurement.

scholarly journals Printed Internal Pentaband WWAN Antenna Using Chip-Inductor-Loaded Shorting Strip for Mobile Phone Application

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Yong-Ling Ban ◽  
Shun Yang ◽  
Joshua Le-Wei Li ◽  
Rui Li
Keyword(s):  
Mobile Phone ◽  
Simple Structure ◽  
Resonant Mode ◽  
Circuit Board ◽  
Printed Antenna ◽  
Mobile Phone Application ◽  
Resonant Modes ◽  
Compact Size ◽  
Close Proximity ◽  
Small Footprint

A compact size on-board printed antenna using capacitive coupled-fed excitation to generate multiple resonant modes for penta-band WWAN operation (GSM850/900/GSM1800/1900/UMTS2100) is presented in this paper. The proposed antenna occupies only a small footprint of 15 × 25 mm2on one corner of the circuit board and a protruded ground of 10 × 15 mm2is displaced with close proximity to the antenna portion. The proposed antenna has a very simple structure which is composed of two separate strips: a loop strip with an inserted chip inductor and an L-shaped feeding strip. The loop strip is shorted to the ground and generates a resonant mode at 890 MHz to cover the GSM850/900 band (824–960 MHz) while the feeding strip contributes to the GSM1800/1900/UMTS210 band (1710–2170 MHz) operation. With such a small size, the proposed antenna can achieve compact integration on the circuit board of the mobile phone, thus the proposed scheme is quite suitable for the slim mobile phone application. Good agreements between simulations and measurements are obtained. Details of proposed antenna are presented and some key parameters are studied.

scholarly journals Film Cooling on a Gas Turbine Rotor Blade

1991 ◽  
Author(s):  
Kenichiro Takeishi ◽  
Sunao Aoki ◽  
Tomohiko Sato ◽  
Keizo Tsukagoshi
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Rotor Blade ◽  
Turbine Rotor ◽  
Suction Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Rotor Blade ◽  
Pressure Surface ◽  
Rotating Blade

The film cooling effectiveness on a low-speed stationary cascade and the rotating blade has been measured by using a heat-mass transfer analogy. The film cooling effectiveness on the suction surface of the rotating blade fits well with that on the stationary blade, but a low level of effectiveness appears on the pressure surface of the rotating blade. In this paper, typical film cooling data will be presented and film cooling on a rotating blade is discussed.

Enhanced Active Constrained Layer Damping Treatment for Broadband Vibration Suppression

2002 ◽  
Vol 8 (6) ◽  
pp. 777-803 ◽  
Author(s):  
Y. Liu ◽  
K. W. Wang
Keyword(s):  
Closed Loop ◽  
Noise Suppression ◽  
Vibration Suppression ◽  
Wide Frequency Range ◽  
Open Loop ◽  
Loop System ◽  
Constrained Layer Damping ◽  
Edge Elements ◽  
Modal Damping ◽  
Active Constrained Layer

In this paper, the Enhanced Active Constrained Layer (EACL) treatment is investigated for broadband damping augmentations on beam structures. The EACL concept was originally proposed to improve the damping performance of the Active Constrained Layer (ACL) by introducing edge elements at the treatment boundaries. It has been recognized that the edge elements can increase ACL performance by enhancing the direct active authority of the piezoelectric constraining layer. It has also been demonstrated that the edge element stiffness and the host structure strain field have significant influence on the overall closed-loop system damping and its various components: the active damping, the closed-loop passive damping, and the open-loop passive (fail-safe property - without any active action) damping. Through utilizing this finding, the present study explores how the EACL performance can be synthesized for multiple mode broadband applications using symmetric configurations. Although the edge elements will tend to reduce the maximum possible open-loop damping of one (or a few) vibration mode, open-loop damping of the other higher order modes could actually be increased. Moreover, the modal damping reduction in the open-loop system can generally be compensated by the significant increase of the closed-loop damping. In other words, the closed-loop EACL system damping over a wide frequency range can be significant, which makes it attractive for broadband vibration and noise suppression.

Bandwidth enhancement of compact patch antennas by loading inverted “L” and “T” strips

2020 ◽  
pp. 1-8
Author(s):  
Abdelheq Boukarkar ◽  
Rachdi Satouh
Keyword(s):  
Patch Antenna ◽  
Resonant Mode ◽  
Patch Antennas ◽  
Bandwidth Enhancement ◽  
Wireless Applications ◽  
Low Profile ◽  
Resonant Modes ◽  
Relative Bandwidth ◽  
Operating Bandwidth ◽  
Patch Edge

Abstract We propose simple designs of compact patch antennas with bandwidth enhancement. Firstly, an inverted “L” strip is loaded onto the corner of one radiating patch edge to create an additional resonant mode which can be combined with that one of the conventional patch to enhance the operating bandwidth. Secondly, the “L” strip is replaced by inverted “T” strip to improve further the bandwidth by creating two adjustable resonant modes. The two proposed patch antennas have the particularity of enhancing the bandwidth significantly without increasing their profile and their overall sizes. Two antenna prototypes are fabricated and tested. Measurements reveal that the patch antenna loaded with “L” strip has stable radiation characteristics with 5.2 times enhancement in the relative bandwidth compared with a conventional patch antenna. The antenna loaded with inverted “T” strip has wider bandwidth (6.25 times wider than the conventional patch) and covers the operating band 5.07–5.89 GHz (15%) with measured peak gain and peak efficiency of 6.25 dBi and 78%, respectively. The proposed antennas are easy to fabricate, have a low-profile, and exhibit good performances which make them good candidates to use in real wireless applications.

Design and control of adaptive vibration absorber for multimode structure

2019 ◽  
Vol 30 (7) ◽  
pp. 1043-1052 ◽  
Author(s):  
Jin-Siang Shaw ◽  
Cheng-An Wang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fuzzy Logic Controller ◽  
Vibration Suppression ◽  
Experimental Testing ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Vibration Absorption ◽  
Resonant Modes ◽  
And Control

In this study, we used two tunable vibration absorbers composed of shape memory alloy to reduce vibration of a platform structure. The natural frequency of the shape memory alloy absorber can be tuned online using a fuzzy logic controller to change the axial force of the shape memory alloy wires through phase transformation. In addition, we employed the finite element method to analyze the dynamic characteristics of the multimode platform structure and to evaluate the effectiveness of the shape memory alloy vibration absorber in terms of platform vibration attenuation. Experimental testing of the platform structure was conducted to verify its modal characteristics. By setting the two shape memory alloy tunable vibration absorbers on two adjacent sides of the platform at 90 degrees to each other and offset from the platform’s center axes, it is shown that all six modes can be covered for vibration absorption. The experiments show that the vibration due to all six mode modal excitations can be attenuated by more than 7.49 dB using the shape memory alloy tunable vibration absorber. Specifically, at the fourth, fifth, and sixth resonant modes, an average of 16.68 dB vibration suppression is observed. Overall, an average of 12.69 dB vibration suppression is achieved for resonant excitation of the entire platform structure when using the designed shape memory alloy tunable vibration absorber.

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