Numerical Noise Transfer Analysis of a Flexible Supported Gearbox Based on Impedance Model and Noise Transfer Function

To investigate the gearbox radiation noise properties under various rotational speeds, a noise prediction method based on impedance model and noise transfer function (NTF) is proposed. One only needs to extract the NTF of the housing once rapid gearbox noise prediction under different working conditions is realized. Taking a flexible supported gearbox as a research object, the external excitation of the housing (the bearing excitation load and isolator excitation load) is calculated through a gear-housing-foundation-coupled impedance model, and the noise transfer function is simulated through the vibroacoustic-coupled boundary element model; then the radiation noise is obtained. Based on this model, the noise transfer analysis of the housing is carried out, different excitation components and NTF components are compared, and the contributions of different excitation components to noise are compared. Results show that the radiation noise of gearbox is mainly excited by the high-speed bearing, while the low-speed bearing and isolator have little influence on noise. At low speed, vertical force, axial force, and moment excitation of bearings all contribute to the radiation noise while at high speed, the gearbox radiation noise is mainly generated by vertical excitation force of bearings.

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Estimation of Phase Noise Transfer Function

Energies ◽

10.3390/en14248234 ◽

2021 ◽

Vol 14 (24) ◽

pp. 8234

Author(s):

Igor Rutkowski ◽

Krzysztof Czuba

Keyword(s):

Transfer Function ◽

Phase Noise ◽

High Speed ◽

Particle Accelerators ◽

Voltage Controlled Oscillator ◽

Frequency Converters ◽

Noise Transfer Function ◽

Residual Noise ◽

First Results ◽

Noise Measurements

Quantifying frequency converters’ residual phase noise is essential in various applications, including radar systems, high-speed digital communication, or particle accelerators. Multi-input signal source analyzers can perform such measurements out of the box, but the high cost limits their accessibility. Based on an analysis of phase noise transmission theory and the capabilities of popular instrumentation, we propose a technique extending the functionality of single-input devices. The method supplements absolute noise measurements with estimates of the phase noise transfer function (also called the jitter transfer function), allowing the calculation of residual noise. The details of the hardware setup used for the method verification are presented. The injection of single-tone and pseudo-random modulations to the test signal is examined. Optional employment of a spectrum analyzer can reduce the time and number of data needed for characterization. A wideband synthesizer with an integrated voltage-controlled oscillator was investigated using the method. The estimated transfer function matches a white-box model based on synthesizer’s structure and values of loop components. The first results confirm the validity of the proposed technique.

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Coupled FEM/BEM Method for Noise Prediction of Common and Sandwich Circular Saw Blades

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.693.463 ◽

2016 ◽

Vol 693 ◽

pp. 463-470 ◽

Cited By ~ 1

Author(s):

Tao Yao ◽

G.L. Duan ◽

Ting Wang

Keyword(s):

Prediction Method ◽

Simulation Method ◽

Vibration Velocity ◽

Noise Prediction ◽

Circular Saw ◽

Circular Saw Blade ◽

Radiation Noise ◽

Saw Blade ◽

The Mathematical Model ◽

Good Agreement

The paper deals with a noise prediction method for circular saw blades by introduction of FEM and BEM. The mathematical model of noise radiation field of circular saw blade is built firstly. Through the model, the vibration characteristic of circular saw blades within a certain frequency range can be calculated and analyzed based on harmonic response. The distributions of surface vibration velocity at a particular frequency are obtained. The above result files are input into the BEM model, acoustic pressure and radiation efficiency on every node are calculated, the distributions of noise was obtained in the acoustic field. Simultaneously, the effect of sandwich structure on noise is evaluated based on the above co-simulation method. Finally, an experiment is used to test the vibration and radiation noise of common and sandwich circular saw blade. Comparison analysis shows that the simulation results are in good agreement with the data of experiment tests.

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Selection of a leading edge noise prediction method for PNoise

The Academic Society Journal ◽

10.32640/tasj.2018.4.214 ◽

2018 ◽

pp. 214-223

Author(s):

AM Faria ◽

MM Pimenta ◽

JY Saab Jr. ◽

S Rodriguez

Keyword(s):

Wind Turbine ◽

Turbine Blades ◽

Prediction Method ◽

Leading Edge ◽

Wind Farms ◽

Broadband Noise ◽

Turbulence Energy ◽

Noise Prediction ◽

Migration Routes ◽

Turbulent Inflow

Wind energy expansion is worldwide followed by various limitations, i.e. land availability, the NIMBY (not in my backyard) attitude, interference on birds migration routes and so on. This undeniable expansion is pushing wind farms near populated areas throughout the years, where noise regulation is more stringent. That demands solutions for the wind turbine (WT) industry, in order to produce quieter WT units. Focusing in the subject of airfoil noise prediction, it can help the assessment and design of quieter wind turbine blades. Considering the airfoil noise as a composition of many sound sources, and in light of the fact that the main noise production mechanisms are the airfoil self-noise and the turbulent inflow (TI) noise, this work is concentrated on the latter. TI noise is classified as an interaction noise, produced by the turbulent inflow, incident on the airfoil leading edge (LE). Theoretical and semi-empirical methods for the TI noise prediction are already available, based on Amiet’s broadband noise theory. Analysis of many TI noise prediction methods is provided by this work in the literature review, as well as the turbulence energy spectrum modeling. This is then followed by comparison of the most reliable TI noise methodologies, qualitatively and quantitatively, with the error estimation, compared to the Ffowcs Williams-Hawkings solution for computational aeroacoustics. Basis for integration of airfoil inflow noise prediction into a wind turbine noise prediction code is the final goal of this work.

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Do You Name Speedy Objects Faster Than Slow Objects: SPEEDED NAMING OR NAMING SPEED? THE AUTOMATIC EFFECT OF OBJECT SPEED ON PERFORMANCE

10.31234/osf.io/78b3h ◽

2018 ◽

Author(s):

Moshe Shay Ben-Haim ◽

Eran Chajut ◽

Ran Hassin ◽

Daniel Algom

Keyword(s):

High Speed ◽

Mental Representations ◽

Reading Aloud ◽

Naming Task ◽

Naming Speed ◽

Low Speed ◽

Everyday Objects ◽

Pictures And Words

we test the hypothesis that naming an object depicted in a picture, and reading aloud an object’s name, are affected by the object’s speed. We contend that the mental representations of everyday objects and situations include their speed, and that the latter influences behavior in instantaneous and systematic ways. An important corollary is that high-speed objects are named faster than low-speed objects despite the fact that object speed is irrelevant to the naming task at hand. The results of a series of 7 studies with pictures and words support these predictions.

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Splatters and Aerosols Contamination in Dental Aerosol Generating Procedures

Applied Sciences ◽

10.3390/app11041914 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1914

Author(s):

Pingping Han ◽

Honghui Li ◽

Laurence J. Walsh ◽

Sašo Ivanovski

Keyword(s):

Particle Size ◽

Disease Transmission ◽

High Speed ◽

Low Speed ◽

Dental Procedures ◽

Dental Equipment ◽

Produce Contamination ◽

Fluorescein Dye ◽

Filter Papers ◽

Airborne Disease

Dental aerosol-generating procedures produce a large amount of splatters and aerosols that create a major concern for airborne disease transmission, such as COVID-19. This study established a method to visualise splatter and aerosol contamination by common dental instrumentation, namely ultrasonic scaling, air-water spray, high-speed and low-speed handpieces. Mock dental procedures were performed on a mannequin model, containing teeth in a typodont and a phantom head, using irrigation water containing fluorescein dye as a tracer. Filter papers were placed in 10 different locations to collect splatters and aerosols, at distances ranging from 20 to 120 cm from the source. All four types of dental equipment produced contamination from splatters and aerosols. At 120 cm away from the source, the high-speed handpiece generated the greatest amount and size (656 ± 551 μm) of splatter particles, while the triplex syringe generated the largest amount of aerosols (particle size: 1.73 ± 2.23 μm). Of note, the low-speed handpiece produced the least amount and size (260 ± 142 μm) of splatter particles and the least amount of aerosols (particle size: 4.47 ± 5.92 μm) at 120 cm. All four dental AGPs produce contamination from droplets and aerosols, with different patterns of distribution. This simple model provides a method to test various preventive strategies to reduce risks from splatter and aerosols.

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Nonlinear transport of rarefied Couette flows from low speed to high speed

Physics of Fluids ◽

10.1063/5.0029680 ◽

2020 ◽

Vol 32 (11) ◽

pp. 112021

Author(s):

Jihui Ou ◽

Jie Chen

Keyword(s):

High Speed ◽

Nonlinear Transport ◽

Low Speed

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Energy Absorption Characteristics of PVC Coarse Aggregate Concrete under Impact Load

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-021-00465-w ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Shi Hu ◽

Huaming Tang ◽

Shenyao Han

Keyword(s):

Compressive Strength ◽

Energy Absorption ◽

High Speed ◽

Coarse Aggregate ◽

Specific Energy Absorption ◽

Low Speed ◽

High Speed Impact ◽

Aggregate Content ◽

Dynamic Compressive Strength ◽

Absorption Characteristics

AbstractIn this paper, polyvinyl chloride (PVC) coarse aggregate with different mixing contents is used to solve the problems of plastic pollution, low energy absorption capacity and poor damage integrity, which provides an important reference for PVC plastic concrete used in the initial support structures of highway tunnels and coal mine roadway. At the same time, the energy absorption characteristics and their relationship under different impact loads are studied, which provides an important reference for predicting the energy absorption characteristics of concrete under other PVC aggregate content or higher impact speed. This study replaced natural coarse aggregate in concrete with different contents and equal volume of well-graded flaky PVC particles obtained by crushing PVC soft board. Also, slump, compression, and splitting strength tests, a free falling low-speed impact test of steel balls and a high-speed impact compression test of split Hopkinson pressure bar (SHPB) were carried out. Results demonstrate that the static and dynamic compressive strength decreases substantially, and the elastic modulus and slump decrease slowly with the increase of the mixing amount of PVC aggregate (0–30%). However, the energy absorption rate under low-speed impact and the specific energy absorption per MPa under high-speed impact increase obviously, indicating that the energy absorption capacity is significantly enhanced. Regardless of the mixing amount of PVC aggregate, greater strain rate can significantly enhance the dynamic compressive strength and the specific energy absorption per MPa. After the uniaxial compression test or the SHPB impact test, the relative integrity of the specimen is positively correlated with the mixing amount of PVC aggregate. In addition, the specimens are seriously damaged with the increase of the impact strain rate. When the PVC aggregate content is 20%, the compressive strength and splitting strength of concrete are 33.8 MPa and 3.26 MPa, respectively, the slump is 165 mm, the energy absorption rate under low-speed impact is 89.5%, the dynamic compressive strength under 0.65 Mpa impact air pressure is 58.77 mpa, and the specific energy absorption value per MPa is 13.33, which meets the requirements of shotcrete used in tunnel, roadway support and other impact loads. There is a linear relationship between the energy absorption characteristics under low-speed impact and high-speed impact. The greater the impact pressure, the larger the slope of the fitting straight line. The slope and intercept of the fitting line also show a good linear relationship with the increase of impact pressure. The conclusions can be used to predict the energy absorption characteristics under different PVC aggregate content or higher-speed impact pressure, which can provide important reference for safer, more economical, and environmental protection engineering structure design.

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Advanced open rotor noise prediction

The Aeronautical Journal ◽

10.1017/s0001924000009817 ◽

2014 ◽

Vol 118 (1208) ◽

pp. 1125-1135 ◽

Cited By ~ 4

Author(s):

M. J. Kingan

Keyword(s):

High Speed ◽

Broadband Noise ◽

Current Status ◽

Prediction Methods ◽

Noise Prediction ◽

Acoustic Data ◽

Rotor Noise ◽

Future Challenges ◽

Open Rotor ◽

Development And Validation

Abstract The purpose of this paper is to describe the current status of open rotor noise prediction methods and to highlight future challenges in this area. A number of analytic and numerical methods are described which can be used for predicting ‘isolated’ and ‘installed’ open rotor tonal noise. Broadband noise prediction methods are also described and it is noted that further development and validation of the current models is required. The paper concludes with a discussion of the analytical methods which are used to assess the acoustic data collected during the high-speed wind-tunnel testing of a model scale advanced open rotor rig.

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