scholarly journals Design and Optimization of Piezoelectric Actuators for Aeroacoustic Noises Control in a Turbofan

2020 ◽  
Author(s):  
M. Perez ◽  
M. Ezzine ◽  
K. Billon ◽  
V. Clair ◽  
J. Mardjono ◽  
...  
Keyword(s):  
Noise Source ◽  
Pressure Fluctuations ◽  
Piezoelectric Actuators ◽  
Frequency Range ◽  
Control Applications ◽  
Design And Optimization ◽  
Aeroacoustic Noise ◽  
Active Approach ◽  
Different Types ◽  
Piezoelectric Structures

Abstract This paper reports on the design and optimization of different types of piezoelectric actuators for aeroacoustic control applications. This study was carried out within the context of the European project CleanSky 2/InnoSTAT. The aim of our work is to reduce the aeroacoustic noises that appear in an airplane turbofan by adding an area of piezoelectric actuators on the Outlet Guide Vanes (OGV). These piezoelectric structures will subsequently be controlled with an active approach and tested in the open-jet anechoic wind tunnel at LMFE. The noise source which has to be reduce/control comes from vortices located in the turbulent flow (which can for example be created by the fan module) interacting with the stator blades. The predominant frequencies and the pressure fluctuations levels related to these vortices rely on the airflow speed and are fixed between 1000Hz and 2000Hz in our case. To reach the target, we plan to manufacture an area of piezoelectric actuators on the intrados and the extrados of the stator blades in order to control the response of the blade to the turbulence of the airflow responsible for the aeroacoustic noise. Several adjacent blades will be equipped with this type of transducers. This study outline the design and the optimization of each piezoelectric cell in order to achieve good results in the frequency range previously defined as well as an acceptable mechanical strength of the blade. A most detailed study on the active shunt will be investigate later on.

Quantification of aerodynamically induced noise and vibration-induced noise in a suction unit

2011 ◽  
Vol 225 (3) ◽  
pp. 617-624 ◽  
Author(s):  
J Prezelj ◽  
M Čudina
Keyword(s):  
Transfer Function ◽  
Noise Reduction ◽  
Noise Source ◽  
Operating Conditions ◽  
Frequency Range ◽  
Centrifugal Blower ◽  
Noise Sources ◽  
Noise And Vibration ◽  
Different Types ◽  
The Individual

Noise, generated by a centrifugal blower, can be divided according to its origin, into aerodynamically induced noise and vibration-induced noise. The contribution of the individual noise source to the total emitted noise is hard to determine, but it is crucial for the design of noise reduction measures. In order to reduce the noise of the centrifugal blower in a broad range of operating conditions, an identification of noise sources needs to be performed. An analysis of the most important noise origin in a centrifugal blower presented in this article was performed by measurements of the transfer function between noise and vibration, under different types of excitation. From the analyses one can conclude that the dominant noise source of a centrifugal blower can be attributed to the aerodynamically generated noise which exceeds the vibration-induced noise for more than 10 dB in a broad frequency range.

scholarly journals Results of an intercomparison for free space antenna factor measurements within the German Calibration Service (DKD)

2016 ◽  
Vol 14 ◽  
pp. 11-16
Author(s):  
Thomas Kleine-Ostmann ◽  
Frank Huncke ◽  
Dieter Schwarzbeck ◽  
Otto Martetschläger ◽  
Jürgen Gaßner ◽  
...  
Keyword(s):  
Free Space ◽  
Frequency Range ◽  
Space Antenna ◽  
Different Types ◽  
Antenna Factor

Abstract. In this paper we discuss the results of an intercomparison for free space antenna factor measurements performed within the German Calibration Service (DKD). Three different types of antennas covering the frequency range from 30 MHz to 26.5 GHz have been calibrated in five different laboratories using different methods and calibration sites to obtain the free space antenna factor. The results agree well within the uncertainties specified by the laboratories suggesting that different approaches and different measurement sites to obtain the free space antenna factor are well compatible.

scholarly journals STUDY OF PROCESSES OF PRESSURE AND IMPULSE FREQUENCY INFLUENCE ON PENETRATION OF LIQUIDS IN THE SAND SAMPLES

2016 ◽  
pp. 120-125
Author(s):  
M. Ya. Habibullin ◽  
R. R. Shangareyev
Keyword(s):  
Experimental Data ◽  
Oil Recovery ◽  
Pressure Fluctuations ◽  
Experimental Studies ◽  
Regression Equations ◽  
Linear Variation ◽  
Frequency Range ◽  
Impulse Frequency ◽  
Overburden Pressure

The article deals with the issues related to the hydrocarbon reservoirs oil recovery enhancement. It describes the bench laboratory experimental studies. The results obtained during determination of fluid leakage through the rock samples and the amount of absorption of pressure fluctuations at various regime parameters are presented. Using the experimental data the regression analysis was performed on the basis of which the qualitative correlations between factorial and resultant features were identified. Using the regression equations the graphic relations were constructed. It was found that with increasing the oscillation frequency of the fluid the amount of fluid passing through the sample of porous medium increased, with the highest value of q reached at the frequency range of 600 ... 1000 Hz. With increase in the oscillations penetration depth the absorption of the amplitude of the pressure fluctuations corresponds to the linear decrease, and with the overburden pressure increase the linear variation of absorption is distorted.

scholarly journals Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

2020 ◽  
Author(s):  
Emma L. M. Lewington ◽  
Stephen J. Livingstone ◽  
Chris D. Clark ◽  
Andrew J. Sole ◽  
Robert D. Storrar
Keyword(s):  
Spatial Distribution ◽  
Dynamic Response ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Fluctuations ◽  
Drainage System ◽  
Different Types ◽  
Form Part ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

Abstract. We identify and map traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada from ArcticDEM data. Meltwater tracks, tunnel valleys and esker splays exhibit several key similarities, including width, spacing, their association with eskers and transitions to and from different types, which together suggest they form part of an integrated drainage signature. We collectively term these features 'meltwater corridors' and propose a new model for their formation, based on observations from contemporary ice masses, of pressure fluctuations surrounding a central conduit. We suggest that eskers record the imprint of a central conduit and meltwater corridors the interaction with the surrounding distributed drainage system. The widespread aerial coverage of meltwater corridors (5–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations and variations in spatial distribution and evolution of the subglacial drainage system, which will modulate the ice dynamic response.

scholarly journals Low Frequency Noise Remove from EEG Signal

2020 ◽  
Vol 9 (1) ◽  
pp. 1510-1513
Keyword(s):  
Human Brain ◽  
Random Noise ◽  
Low Frequency ◽  
Frequency Noise ◽  
Eeg Signal ◽  
Low Frequency Noise ◽  
Frequency Range ◽  
Average Value ◽  
Different Types ◽  
The Brain

The electrical activity of the brain recorded by EEG which used to detect different types of diseases and disorders of the human brain. There is contained a large amount of random noise present during EEG recording, such as artifacts and baseline changes. These noises affect the low -frequency range of the EEG signal. These artifacts hiding some valuable information during analyzing of the EEG signal. In this paper we used the FIR filter for removing low -frequency noise(<1Hz) from the EEG signal. The performance is measured by calculating the SNR and the RMSE. We obtained RMSE average value from the test is 0.08 and the SNR value at frequency(<1Hz) is 0.0190.

Noise Spectrum Measurements from 10 Hz to 1 MHz using a Tunable Switching Radiometer. I. Instrumentation

1971 ◽  
Vol 49 (7) ◽  
pp. 849-852 ◽  
Author(s):  
H. A. Buckmaster ◽  
R. S. Rathie
Keyword(s):  
High Precision ◽  
Noise Source ◽  
Noise Spectrum ◽  
Measurement Precision ◽  
Frequency Range ◽  
Direct Reading ◽  
Spectrum Measurements ◽  
Averaging Time

The first application of a switching (Dicke) radiometer to high-precision, noise spectrum measurements from 10 Hz to 1 MHz is described. The solution of the instrumentation problems unique to this frequency range are discussed in detail. The advantage of this radiometer is that it can be employed in a null mode so that it is direct reading and the measurement precision at all frequencies is limited fundamentally by the bandwidth and averaging time or by the calibration of the reference noise source and its attenuator.

The Effect of Aspect Ratio on Wall Pressure Fluctuations at a Wing-Plate Junction

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
M. Awasthi ◽  
J. Rowlands ◽  
D. J. Moreau ◽  
C. J. Doolan
Keyword(s):  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Wide Frequency Range ◽  
Wall Pressure ◽  
Frequency Range ◽  
Three Dimensional Flow ◽  
Wall Pressure Fluctuations ◽  
Aspect Ratios

Abstract Measurements of the wall pressure fluctuations near a wing-plate junction were made for wings with three different aspect ratios (AR) of 0.2, 0.5, and 1.0 at several angles of attack. The chord-based Reynolds number for each wing was 274,000. The results show that the wall pressure fluctuations are a function of wing AR for cases where AR≤ 1.0. For each wing, the pressure fluctuations are highest upstream of the wing leading-edge due to three-dimensional flow separation; wings with AR = 1.0 and 0.5 show comparable levels, while those with AR = 0.2 show lower fluctuation levels over a wide frequency range. Downstream of the leading-edge, the pressure fluctuations decay rapidly on both sides of the wing until the maximum thickness location after which little variation is observed. The pressure fluctuations downstream of the leading-edge on the suction-side were observed to be comparable for AR = 0.2 and 0.5, while those for AR = 1.0 were higher in magnitude. On the pressure-side, the pressure fluctuations near the leading-edge are a weak function of AR; however, those further downstream remain independent of AR. The pressure fluctuations aft of the wing on the suction-side are more coherent for lower ARs and show higher convection velocity, possibly due to an interaction between the tip and the junction flows for lower ARs.

scholarly journals The calculation, design and optimization of sandwich panels using author’s programs of the automated designing of development

2018 ◽  
Vol 251 ◽  
pp. 04006
Author(s):  
Stanislav Petrov ◽  
Irina Kuznetsova ◽  
Yuri Doladov ◽  
Nikita Krasnov
Keyword(s):  
Sandwich Panels ◽  
Middle Layer ◽  
Russian Language ◽  
Design And Optimization ◽  
Cost Criterion ◽  
Different Types ◽  
The Moment ◽  
The Cost ◽  
Program Interface ◽  
Building Engineering

Three-layer sandwich panels are widely used in insulation of walls and roofing of buildings and other various structures. At the moment building products markets are full of various types of panels by produced different manufactures but skinned with one and the same material only. Panels skinned with two different types of materials are widely used in the sphere of transport. It may be also of considerable economical effect in building engineering. The article presents an analysis of the current state of the problem of calculation of thin-walled profiles in load-bearing structures. The authors developed a program of automated calculation of three-layer panels. The program is certified in Russia. The program allows you to optimize the panel parameters according to the cost criterion. The article presents the basic calculation ideas incorporated in the algorithm of the program. The figures show the program interface. To date, the program has only one Russian language interface. The paper introduces automated methods of singleand multi-span sandwich panels trial design. Different types of materials can be used while skinning these panels. Their middle-layer shift and compliance of supporting structures are taken into account.

Influence of various multilayer LTCC systems on dielectric properties’ stability in GHz frequency range

2016 ◽  
Vol 33 (3) ◽  
pp. 136-140 ◽  
Author(s):  
Tibor Rovensky ◽  
Alena Pietrikova ◽  
Igor Vehec ◽  
Martin Kmec
Keyword(s):  
Dielectric Properties ◽  
Design Methodology ◽  
Middle Layer ◽  
Ring Resonators ◽  
Frequency Range ◽  
Content Type ◽  
Different Types ◽  
Good Repeatability ◽  
Microstrip Ring ◽  
Multilayer Substrate

Purpose The purpose of this paper is to create multilayer substrate (composite) from various low temperature co-fired ceramic (LTCC) substrates by their mutual combinations and to analyse influence of these multilayer substrates on dielectric properties in GHz frequency range. Design/methodology/approach GreenTape 951, GreenTape 9K7 and Murata LFC were used to create compound multilayer substrates that include three layers: middle layer is from Murata LFC, and both upper and bottom layers are either from GreenTape 951 or GreenTape 9K7. Shrinkage in all x-, y- and z-axes of all substrates including multilayer substrates were analysed, and influence of different shrinkage on dielectric properties was examined by microstrip ring resonators applied on all mentioned of substrates. Findings The middle layer of Murata LFC has significant influence on shrinkage value of composites which has a good repeatability and minimalizes problems with design of multilayer LTCC devices. Impact of middle layer from Murata LFC on dielectric constant is not significant, but on the other hand Q factor (loss tangent) of these composites is increased according to inhomogeneity between single LTCC layers, especially at frequency around 6 GHz. Originality/value The novelty of this work lies in creating multilayers systems from different types of LTCC substrates to find combination with the most suitable physical and dielectric properties for various purposes in GHz range applications.

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