Study on Noise in New Roller Chain Drives

2012 ◽  
Vol 522 ◽  
pp. 598-601
Author(s):  
Wei Sun ◽  
Xiao Lun Liu ◽  
Wen Cheng Wang ◽  
Li Yan He ◽  
Jia Jun Liu
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
High Speed ◽  
Low Noise ◽  
The Other ◽  
Metal Mesh ◽  
Roller Chain ◽  
Polyurethane Composite ◽  
Noise Characteristics ◽  
The Impact

In order to mitigate the impact and the polygon effect of the chain and the sprocket during the meshing process and achieve the purpose of noise reduction, a Hlow noiseH nanostructured metal mesh-polyurethane composite material split roller chain was designed by means of changing structure and material of chain roller. Noise testing and frequency spectrum analysis were conducted, for the new roller chain and the other three kinds of the same specification chains with different structural rollers, on the closed force flow noise test bench researched and developed independently. The results show that the new roller chain can absorb some of the impact energy, and reduce vibration and noise of chain drive. The noise level generated by the new roller chain is significantly lower than the other tested roller chains, especially in high frequency and high speed. The difference in noise level is actually 3-11dB in driving sprocket speed of 1000r/min, and a significant noise reduction is achieved. The results also verify low noise characteristics of the new roller chain and rationality of design method.

Test and Analysis of Bush Roller Chains for Noise Reduction

2011 ◽  
Vol 52-54 ◽  
pp. 430-435
Author(s):  
Xiao Lun Liu ◽  
Wei Sun ◽  
Song Ding ◽  
Jian Fang Liu ◽  
Yu Ying Wang ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Impact Energy ◽  
Noise Level ◽  
Low Noise ◽  
Working Environment ◽  
The Other ◽  
Chain Drive ◽  
Noise Characteristics ◽  
Testing Data ◽  
Different Types

A low noise duplex bush chains with split rollers was developed through changing roller structure to reduce noise of bush roller chains. The split rollers could absorb more impact energy, mitigate meshing impact and reduce chain drive noise. The noise generated by different types of duplex bush roller chains was carried out to test in same speed, low noise characteristics of duplex sleeve chains with split rollers was verified. By analysis of testing data, noise level of duplex sleeve chains with split rollers compared with that of the other duplex bush roller chains was reduced by the average 3 ~ 8dB, and low 10 ~ 13dB than that of 16A simplex sleeve roller chains. The chains made chain drive significantly improve in the working environment, with steady transmission, strong bearing, low noise, and a significant noise reduction was achieved.

Evolution of the Turboprop for High Speed Air Transportation

1978 ◽  
Author(s):  
G. E. Holbrook ◽  
G. Rosen
Keyword(s):  
Fuel Consumption ◽  
Noise Level ◽  
High Speed ◽  
Cost Effective ◽  
Air Transportation ◽  
Low Noise ◽  
The Other ◽  
Propulsion Systems ◽  
Maintenance Costs ◽  
Passenger Comfort

Since they first entered military and commercial service during the 1950’s, U.S.-manufactured turbopropeller engines have proved to be reliable, fuel-efficient propulsion systems for aircraft. Despite their somewhat greater mechanical complexity when comprared with turbofans, the repair and maintenance costs of the turboprops compare very favorably with those of the other types, and their substantially reduced fuel consumption and low noise level merit serious consideration for aircraft in an energy and environmentally critical future. Advancements in propeller/fan aerodynamic and structural technologies now permit flight speeds up to Mach 0.85, making turly cost-effective aircraft possible, while retaining present standards of passenger comfort and powerplant reliability.

Comparison of Noise Reduction Performance Evaluation Methods for Low-Noise Pavement in Korea- Part

2021 ◽  
Vol 263 (4) ◽  
pp. 2930-2939
Author(s):  
Byungchae Kim ◽  
Hyunjin Kim ◽  
Wonuk Kang
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Measurement Method ◽  
Road Traffic ◽  
Low Noise ◽  
Management Standards ◽  
Close Proximity ◽  
Porous Pavement ◽  
Reduction Effect ◽  
Measurement Location

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.

Development and Application of a Multi-Disciplinary Multi-Regime Design Methodology of a Low-Noise Contra-Rotating Open-Rotor

2015 ◽  
Author(s):  
Michaël Leborgne ◽  
Timothée Lonfils ◽  
Ingrid Lepot
Keyword(s):  
Noise Reduction ◽  
High Speed ◽  
Design Methodology ◽  
Design Procedure ◽  
Low Noise ◽  
Design Parameters ◽  
Mechanical Constraints ◽  
Open Rotor ◽  
Mechanical Optimization ◽  
Lifting Line

This paper focuses on the development and exploitation of a multi-disciplinary, optimization-assisted, design methodology for contra-rotating open-rotors. The design procedure relies on a two-step approach. An aero-mechanical optimization is first performed to generate a geometry with good performances over several high-speed points representative of a mission. This geometry is subsequently used as the baseline of an aero-mechanical-acoustic optimization focusing on interaction noise reduction at Cutback and Sideline low-speed points. In terms of design parameters, both rotors are modified for the first phase but only the upper part of the front rotor is altered for the noise minimization. A fully-automatic high-fidelity aero-mechanical-acoustic computational chain with fluid-structure coupling is exploited in combination with evolutionary algorithms assisted by surrogate models for the constrained-optimization process. The acoustic footprint is estimated by a simplified but fast and relevant formulation combining an unsteady lifting-line and an acoustic propagation method. The best geometry of the first design gains 1.2pt in weighted efficiency while respecting all the aero-mechanical constraints. The acoustic optimization shows that noise reduction at Sideline and Cutback points is strongly antagonistic. However, significant Sideline noise reduction from 3.5 to 5.5dB depending on the harmonics is achieved while maintaining Cutback noise and without major degradation of high-speed efficiency.

Evaluation of Noise Characteristics of Drainage and Water Supply Systems in Apartment Bathrooms

2014 ◽  
Vol 1025-1026 ◽  
pp. 987-990
Author(s):  
Jun Oh Yeon ◽  
Kyoung Woo Kim ◽  
Kwan Seop Yang ◽  
Byung Kwon Lee
Keyword(s):  
Water Supply ◽  
Noise Level ◽  
Drainage System ◽  
Low Noise ◽  
Sound Level ◽  
Water Supply Systems ◽  
Apartment Building ◽  
Noise Characteristics ◽  
Measurement Results ◽  
Supply Systems

We have developed a low-noise drainage system, which was installed in bathrooms of apartment building units as well as in a mock-up test building, to evaluate the noise level in order to reduce the noise produced in the bathrooms of multiunit dwellings. The drainage system installed in the mock-up building consists of six types of detachable drains, and the level of noise produced during toilet use in the upper unit was measured in the lower unit. The measurement results showed that low-noise drainage 4 exhibited the Leq(equivalent continuous sound level) at 34.7 dB(A). The noise measurement results of various types of low-noise drains installed in an apartment building showed that the Leqduring toilet use was 46.7 dB(A) on average, and the Leqduring sink use was 40.5 dB(A) on average.

scholarly journals Analysis of Skid Resistance and Noise Characteristics for Varieties of Concrete Pavement

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Jinmiao Fang ◽  
Jinsong Tu ◽  
Kunming Wu
Keyword(s):  
Noise Level ◽  
Evaluation Criteria ◽  
Sound Intensity ◽  
Low Noise ◽  
Concrete Pavement ◽  
Skid Resistance ◽  
Concrete Pavements ◽  
Noise Levels ◽  
Cement Concrete ◽  
Noise Characteristics

To establish evaluation criteria for the pavement skid resistance and noise level in tunnels pavements, the zoning and control standards for skid resistance and concrete pavement noise were examined. Transverse friction coefficient (TFC) test equipment and the on-board sound intensity (OBSI) method were used to evaluate the antisliding characteristics and noise levels of several tunnel pavements. The results indicated poor antisliding characteristics and noise levels in ordinary grooved cement concrete pavement, whereas new types of cement concrete pavements, such as exposed concrete pavements and polymer-modified cement concrete pavements, had good antisliding characteristics and achieved low noise levels. Combined with the cluster analysis method, a zoning method for the antisliding and noise level in concrete pavement is proposed. The antisliding characteristics and noise levels of the pavement are divided into three zones. To ensure safety and comfort during driving, the antisliding value (SFC) of the tunnel pavement should be more than 50, and the noise level should not exceed 105 dB. Finally, the correlation between the antisliding and noise levels for pavement was analyzed. The results indicated that the antiskiding value of pavement has a strong correlation to the noise level.

Low noise with wood milling "Airface" constructions

2019 ◽  
Vol 106 ◽  
pp. 49-56
Author(s):  
GRZEGORZ WIELOCH
Keyword(s):  
Noise Reduction ◽  
High Speed ◽  
Air Flow ◽  
Low Noise ◽  
Bearing Surface ◽  
Wood Industry ◽  
Wood Processing ◽  
New Methods ◽  
Grooved Surface ◽  
Milling Tools

Low noise with wood milling"airface" constructions. The noise surrounds us everywhere, constituting a disruptive component of our lives. In the wood industry it is more than in other industries due to the specificity of wood processing carried out by high-speed tools. GUS data say that in 2012 as many as 53% of employees worked in noise. Hence the necessity of constant search for new methods of noise reduction. One of them is the use of a grooved surface patterned on the plumage of owls in the construction of milling heads. Their characteristic construction makes the flight of owls almost silent. this is possible due to the special construction of ailerons, which form the bearing surface of the wing. The "owl's wing" smoothes the air flow with a serrated edge and scatters the noise. This allows for almost silent flight characteristics without adversely affecting aerodynamics. Leuco has used this concept of learning from nature to make the milling tools even more aerodynamic, and to get further noise reduction effects! Leuco has submitted a patent for this aerodynamic head design called "airface".

Seismic noise characteristics in Chinese mainland

2020 ◽  
Author(s):  
Fang Wang ◽  
Weitao Wang ◽  
Jianfeng Long ◽  
Leiyu Mu
Keyword(s):  
Noise Level ◽  
Seismic Noise ◽  
Vertical Component ◽  
Chinese Mainland ◽  
Low Noise ◽  
Noise Characteristics ◽  
Power Spectral ◽  
Short Period ◽  
Power Spectral Densities ◽  
Noise Models

<p>Using the three-component continuous waveform recordings of 880 broadband seismic stations in China Seismic Network from January 2014 to December 2015, we calculated power spectral densities and probability density functions over the entire period for each station，and  investigated the characteristics of seismic noise in Chinese mainland. The deep analysis on the vertical recordings  indicates that the spatial distribution of noise levels is characterized by obvious zoning for different period bands.  Densely populated areas have higher short-period noise level than sparsely populated ones, suggesting that short-period noise is related to the intensity distribution of human activities such as transportation and industry. Meanwhile，the short-period noise level near the basin is higher than the mountainous areas，which is probably caused by the amplification effect of the sedimentary layer. The microseism energy  gradually decreases from the southeastern coastal lines to the inland regions. Furthermore, horizontal-component noise level  showed a striking constrast with the vertical component at microseismic and long-period bands. In consideration of  the zoning chracteristics and the need of seismic observations, high and low noise models were  acquired for each network , which were proved to be a more effective tool to identify locally abnormal signals including earthquake, instrumental error and various distrubance compared with the global new high and low model. </p>

Paper 16: A Study of Tractor Noise Control

1969 ◽  
Vol 184 (17) ◽  
pp. 149-169
Author(s):  
J. Matthews ◽  
J. D. C. Talamo
Keyword(s):  
Hearing Loss ◽  
Diesel Engine ◽  
Noise Reduction ◽  
Noise Level ◽  
Exhaust System ◽  
Low Noise ◽  
Acoustic Features ◽  
Noise Levels ◽  
Engine Design ◽  
High Incidence

A high incidence of hearing loss has been encountered among tractor drivers, and noise levels are shown to be further increased by the addition of cabs, particularly those which are structurally strong to resist crushing if the vehicle overturns. Some reductions in the noise level of the operator's environment can be obtained by covering the engine or by exhaust system modifications, while possible future improvements to diesel engine design may effect a significant improvement. However, it is proposed that noise reduction is likely to be achieved by attention to acoustic features of the operator's cab. The inclusion of resilient mounts, substantial floors and bulkheads, and acoustically absorbent linings are all shown to provide worthwhile improvements and, in combination, these measures can reduce noise levels from more than 100 dBA to 90 dBA or less. Where the tractor is fitted with a safety frame only, a low noise fabric cladding is shown to be feasible.

Experimental Investigations of Effects of Centrifugal Compressor Impeller Design on Noise Characteristics

2014 ◽  
Author(s):  
Kyoung-Ku Ha ◽  
Chang-ha Lee ◽  
Yong-sun Park ◽  
Shin-hyoung Kang ◽  
Chi-young Park ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Centrifugal Compressor ◽  
Noise Level ◽  
Processing System ◽  
Design Procedure ◽  
Low Noise ◽  
Design Flow ◽  
Normal Operation ◽  
Efficient Operation ◽  
Noise Characteristics

The subject of this study is a centrifugal compressor for fuel-cell vehicles which produces compressed air and sends it to the cathode channels of a fuel-cell stack. It uses up a lot of electricity and it is the only component in the processing system that has a rotating part moving a high angular velocity. So, it is important to improve the centrifugal compressor in efficiency and noise respects. As demand for quiet and comfort of vehicles increases recently, it becomes more and more important for the compressor to achieve low noise level. But it is difficult to design a suitable compressor with a conventional design method, which was formulated to provide highly efficient operation at the design point without considering the noise. Actually, the noise of a compressor is hard to be considered in the early steps of the design procedure because of a lack of information. So, this study aims to describe noise characteristics of centrifugal compressors experimentally and to pull noise considerations into a design procedure of the centrifugal compressor. According to previous studies, a tonal component leads to overall noise of a compressor in normal operation and there is a close connection between the instability intensity and the circumferential flow fluctuations of an impeller. Therefore an experimental study was designed to check the aero-acoustic characteristics of the impeller. An existing compressor was modified to install pressure transducers at the inlet and outlet of the impeller. And two microphones were installed to measure noise signals of the compressor in a sealed room. Tests were carried out to investigate the phenomena governing the overall noise and the dominant noise source of the centrifugal compressor. Then pressure fluctuations, noise signals and spectra of them were examined closely. After that, several impellers varying exit blade angles and design flow coefficients were tested also. They were all designed to satisfy the same pressure performance at a design mass-flow rate. Then investigations into the noise characteristics were carried out to find out effects of the impeller design variables on them. The results show that a large value of a blade angle is good for efficiency and noise level of the compressor. It is expected to be an optimal value to improve noise characteristics in terms of the design flow coefficient. The experimental facility, conditions and the results were described in this paper minutely.

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