Helicopter Thickness Noise Reduction Possibilities Through Active On-Blade Acoustic Control

2010 ◽  
Vol 47 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Gaurav Gopalan ◽  
Fredric H. Schmitz
Keyword(s):  
Noise Reduction ◽  
Acoustic Control

Tonal Noise Reduction for a Maneuverable Marine Hydrokinetic Cycloturbine Vehicle Using Turbine Clocking

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Margalit Z. Goldschmidt ◽  
Michael L. Jonson ◽  
Joseph Horn
Keyword(s):  
Noise Reduction ◽  
Experimental Work ◽  
Tonal Noise ◽  
Aquatic Life ◽  
Acoustic Control ◽  
Acoustic Signature ◽  
Load Cells ◽  
Marine Hydrokinetic ◽  
Sustainable Power ◽  
Harmful Effects

Abstract A Marine Hydrokinetic (MHK) cycloturbine vehicle can exploit tidal currents to generate sustainable power and also has the ability to station keep and maneuver. The vehicle consists of four counterrotating cycloturbines, which radiate sound underwater. Acoustic control is important to curtail the vehicle’s vibrations and acoustic signature, potentially preventing harmful effects on aquatic life, as well as to reduce the vehicle’s fatigue for longer deployment. A method of reducing the radiated acoustics of the vehicle is determined for tones at foil passing frequency and multiples, by means of clocking the blades between turbines. Experimental work includes testing of a subscale demonstrator in ARL’s Reverberant Tank facility. Fixing the subscale demonstrator to a reaction frame in the tank provides the ability to measure the generated loads using load cells. These measurements verify the effects of turbine clocking on the radiated acoustics.

Active Control of Structure-Borne Road Noise Using Vibration Actuators

1998 ◽  
Vol 120 (2) ◽  
pp. 517-523 ◽  
Author(s):  
W. Dehandschutter ◽  
P. Sas
Keyword(s):  
Noise Reduction ◽  
Laboratory Experiments ◽  
Frequency Range ◽  
Road Noise ◽  
Control Approach ◽  
Noise Radiation ◽  
Acoustic Control ◽  
Numerical Tools ◽  
Control Set ◽  
Set Up

Structure-borne road noise is generated by road induced excitation forces. The control approach presented here relies on the use of vibration actuators to modify the vibration behavior of the car body such that its noise radiation efficiency is decreased (Active Structural Acoustic Control—ASAC). The controller is optimized using laboratory experiments and numerical tools to simulate the performance a complete vehicle control set-up. Road tests yield a 6.9 dB noise reduction in the frequency range 75–105 Hz at the error microphone and 6.1 dB noise reduction at the passenger’s ear.

Enclosure Active Structure Acoustic Control Based on Multi-Agent System

2012 ◽  
Vol 605-607 ◽  
pp. 1142-1148
Author(s):  
Zhi Chen Li ◽  
Lin Ning Gu ◽  
Nan Chen
Keyword(s):  
Noise Reduction ◽  
Noise Control ◽  
Divide And Conquer ◽  
Flexible Plate ◽  
Multi Agent System ◽  
Control Field ◽  
Agent System ◽  
Active Structure ◽  
Acoustic Control ◽  
Multi Agent

For enclosure noise reduction, limited discrete distributed control is an ideal choice when it is difficult to understand sound-structure coupling characteristics accurately. An enclosure medel of two flexible plates is established in this paper. Two secondary control channels are constructed by applying distributed force on flexible plate. In the basis of control problem decomposition a multi-agent system (MAS) structure is established and the coordination relationship between agents is regulated. The simulaition resultes show the Active Structure Acoustic Control based on MAS is effective. The MAS control method improves the extension of noise control system and can be used in “plug-and–play” control field to realize noise reduction. MAS is a better effective tool to realize the divide-and-conquer approach in enclosure noise control field.

Satisfaction With Noise Reduction Circuits

1993 ◽  
Vol 2 (1) ◽  
pp. 51-53 ◽  
Author(s):  
Ruth A. Bentler
Keyword(s):  
Noise Reduction

КОНЦЕПЦІЯ СТВОРЕННЯ СИЛОВОЇ УСТАНОВКИ СІМЕЙСТВА РЕГІОНАЛЬНИХ ПАСАЖИРСЬКИХ ЛІТАКІВ АН-148/АН-158

2019 ◽  
pp. 50-63
Author(s):  
О. Д. Донець ◽  
В. П. Іщук
Keyword(s):  
Power Plant ◽  
Noise Reduction ◽  
Fuel Consumption ◽  
Electronic System ◽  
Electronic Control ◽  
Level Of Automation ◽  
Auxiliary Power ◽  
Power Plant Control ◽  
Technical Status ◽  
Air Intake

The basic results of calculation and research works carried out in the process of creation of power unit of regional passenger airplanes’ family are given. The design features of the propulsion engines and engine of the auxiliary power plant are described. The aforementioned propulsion system includes propulsion engines D-436-148 and engine AI-450-MS of auxiliary power plant. In order to comply with the requirements of Section 4 of the ICAO standard (noise reduction of the aircraft in site), in part of ensuring the noise reduction of engines, when creating the power plant of the An-148/An-158 aircraft family, a single- and double-layer acoustic filler was used in the structure of the engine nacelle and air intake. The use of electronic system for automatic control of propulsion engines such as FADEC and its integration into the digital airborne aircraft complex ensured the operation of engines, included in the power plant provided with high specific fuel consumption, as well as increased the level of automation of the power plant control and monitoring, and ensured aircraft automation landing in ICAO category 3A. In addition, the use of the aforementioned electronic system, allowed to operate the power plant of the aircraft in accordance with technical status. The use of the AI-450-MS auxiliary power plant with an electronic control system such as FADEC, and the drive of the service compressor from a free turbine, eliminated the effect of changes in power and air takeoff, on the deviation of the engine from optimal mode, which also minimized the fuel consumption. The use of fuel metering system TIS-158, allowed to ensure control of its condition and assemblies, without the use of auxiliary devices, built-in control means. In the fire protection system, the use of the electronic control and monitor unit, as well as the use of digital serial code for the exchange of information between the elements of the system and the aircraft systems, has reduced the number of connections, which increased the reliability of the system and reduced its weight characteristics.

AN IMPROVED ARMORED VEHICLE KRAZ “FIONA” NOISE SILENCER

2019 ◽  
pp. 21-26
Author(s):  
Volodymyr Fedorov ◽  
Vasyl’ Yanovsky ◽  
Dmytro Kovalshuk
Keyword(s):  
Noise Reduction ◽  
Speed Of Sound ◽  
Acoustic Waves ◽  
Noise Level ◽  
Combustion Engine ◽  
Environmental Aspect ◽  
Exhaust Gases ◽  
Ecological Requirements ◽  
On The Road ◽  
Armored Vehicle

Ecological requirements for cars grow from year to year, both in the world as a whole, and in Ukraine in particular. This is especially true of noise pollution. Additionally, noise reduction becomes relevant, taking into account the conduct of military operations during the last 5 years on the territory of Ukraine. The war has caused a special need for military vehicles for which masking properties are vital. Noise is a serious disincentive factor. Therefore, its reduction for a military vehicle, apart from the environmental aspect, is of a purely military nature, that is, it is extremely important. The car has many sources of noise there are many ways to deal with them. One of the most powerful source of noise is the sleeping bag. This kind of noise is reduced by means of silencers of noise. The vast majority of silencer data in the basis of its design has a reactive (or resonant) muffler. To calculate the jet silencer you must know the speed of sound in the sleeping bags. In order to increase the acoustic efficiency of reactive and resonant mufflers of exhaust gases noise of the ICE of cars, an experimental method was proposed for determining the speed of sound in the sleighs. Implementation of the method is carried out by measuring the attenuation of acoustic waves. The noise level of the bedrooms is measured without silencer and silencer. Based on the data obtained, the noise reduction performance of the residual is established. From the well-known formula, based on the calculation of the efficiency of the silencing of a jet muffler, a formula is obtained for calculating the speed of sound in the sleeping quays. In this formula, all parameters are known: the level of silencer efficiency, the noise level of the sleeping, the ratio of areas of cross sections of the muffler and the inlet pipe and the length of the muffler. The sound speed thus established can continue to be used not only for engines of the type for which measurements and calculations were made, but also with a certain approximation for some other types of engines. This method provides high accuracy for determining the required parameter. In the given work on the example of the armored car KrAZ “Fiona” the calculation of efficiency increase of the reactive silencer is made due to the above-mentioned method. Also, the projected decrease in the external noise level of the KrAZ Armored Vehicle “Fiona” is considered by determining the speed of sound in the recesses on the trunk cycle on the road with acceleration up to speed of 50 km/h (75 km/h) and the movement with this speed, as well as when driving at a speed of 45 km/h. Keywords: transport, armored car, internal combustion engine, exhaust, exhaust gases, noise, source, acoustic efficiency, acoustic efficiency, speed of sound, jet muffler.

Common-mode Noise Reduction Circuit Design for Biosignal Acquisition System—in Comparison with the DRL

2019 ◽  
Vol 139 (12) ◽  
pp. 657-662
Author(s):  
Minghui Chen ◽  
Jianqing Wang ◽  
Daisuke Anzai ◽  
Georg Fischer
Keyword(s):  
Noise Reduction ◽  
Circuit Design ◽  
Acquisition System ◽  
Common Mode
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