scholarly journals The impact of rotational speed and water volume on textile translational motion in a front-loading washer

2018 ◽  
Vol 89 (16) ◽  
pp. 3401-3410 ◽  
Author(s):  
Hong Liu ◽  
R Hugh Gong ◽  
Pinghua Xu ◽  
Xuemei Ding ◽  
Xiongying Wu
Keyword(s):  
Residence Time ◽  
Rotational Speed ◽  
High Speed ◽  
Translational Motion ◽  
Processing System ◽  
Water Volume ◽  
Motion Path ◽  
Rotational Axis ◽  
Passive Region ◽  
The Impact

Textile motion in a front-loading washer has been characterized via video capturing, and a processing system developed based on image geometric moment. Textile motion significantly contributes to the mass transfer of the wash solution in porous materials, particularly in the radial direction (perpendicular to the rotational axis of the inner drum). In this paper, the velocity profiles and residence time distributions of tracer textiles have been investigated to characterize the textile dynamics in a front-loading washer. The results show that the textile motion varies significantly with the water volume and rotational speed, and that the motion path follows certain patterns. Two regions are observed in the velocity plots: a passive region where the textile moves up with low velocity and an active region where the textile falls down with relatively high speed. A stagnant area in the residence time profile is observed. This corresponds to the passive region in the velocity profile. The stagnant area affects the mechanical action, thus influencing washing efficiency and textile performance. The findings on textile dynamics will help in the development of better front-loading washers.

Modal Comparison of Crankshaft under Multi-Speed

2014 ◽  
Vol 533 ◽  
pp. 48-51
Author(s):  
Ran Ran Wang ◽  
Xian Bin Teng ◽  
Yan Ming Xu ◽  
Tao Ge
Keyword(s):  
Centrifugal Force ◽  
Vibration Frequency ◽  
Rotational Speed ◽  
High Speed ◽  
Vibration Mode ◽  
Large Deviation ◽  
Frequency Change ◽  
Low Speed ◽  
The Impact

Considering the effect of centrifugal force generated by the rotation to the crankshaft frequency and vibration mode, the frequency and vibration mode of multi-speed cases are calculated. The results showed that the impact of the centrifugal force on the crankshaft vibration increases with the increase of rotational speed, especially in the high speed region, this phenomenon is more obvious. From low speed to high speed, the vibration frequency has a large deviation, which shows that in this case, it is necessary to consider the frequency change caused by pre-stress.

The Analysis of Self-Excited Vibration in Processing System of Single Blade Rigid Boring Reamer

2014 ◽  
Vol 945-949 ◽  
pp. 761-765
Author(s):  
Zhen Dong ◽  
Xing Quan Shen
Keyword(s):  
High Speed ◽  
Processing System ◽  
Common Phenomenon ◽  
Deep Processing ◽  
High Speed Cutting ◽  
Excited Vibration ◽  
Precision Hole ◽  
The Stability ◽  
The Impact ◽  
Hole Machining

The reaming process with rigid single blade reamers boring is one kind of deep processing methods which develop rapidly in recent years,which has a series of advantages such as high-speed cutting, auto-oriented, low surface roughness and so on.Appear as one kind of precision hole processing technology in the deep hole processing currently,and shows the superiority of processing.The self-excited vibration is a common phenomenon in deep processing,and seriously affect the stability of hole machining and processing quality.It performance very obvious in rigid single blade reamers boring processing,and has a certain degree of particularity. Established as a mathematical model of the rigid boring reamerThe analysis of mechanism of Self-excited vibration in reaming processing of single blade rigid boring reamer, and the study the impact of the friction characteristics of the guide block and the hole in self-excited vibrations,provide the basis for the inhibition of self-excited vibration.

Droplet Impingement and Vapor Layer Formation on Hot Hydrophobic Surfaces

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Ji Yong Park ◽  
Andrew Gardner ◽  
William P. King ◽  
David G. Cahill
Keyword(s):  
Heat Transfer ◽  
Residence Time ◽  
High Speed ◽  
Hydrophobic Surface ◽  
Vapor Layer ◽  
Si Substrate ◽  
Hydrophobic Surfaces ◽  
High Speed Imaging ◽  
Temperature Range ◽  
The Impact

We use pump–probe thermal transport measurements and high speed imaging to study the residence time and heat transfer of small (360 μm diameter) water droplets that bounce from hydrophobic surfaces whose temperature exceeds the boiling point. The structure of the hydrophobic surface is a 10 nm thick fluorocarbon coating on a Si substrate; the Si substrate is also patterned with micron-scale ridges using photolithography to further increase the contact angle. The residence time determined by high-speed imaging is constant at ≈1 ms over the temperature range of our study, 110 < T < 210 °C. Measurements of the thermal conductance of the interface show that the time of intimate contact between liquid water and the hydrophobic surface is reduced by the rapid formation of a vapor layer and reaches a minimum value of ≈0.025 ms at T > 190 °C. We tentatively associate this time-scale with a ∼1 m s − 1 velocity of the liquid/vapor/solid contact line. The amount of heat transferred during the impact, normalized by the droplet volume, ranges from 0.028 J mm − 3 to 0.048 J mm − 3 in the temperature range 110 < T < 210 °C. This amount of heat transfer is ≈1–2% of the latent heat of evaporation.

Influence of rotational speed on the impact characteristics caused by a localized defect of the outer raceway in a ball bearing under an axial load

2020 ◽  
Vol 234 (3) ◽  
pp. 498-513
Author(s):  
Pingping Hou ◽  
Liqin Wang ◽  
Qiuyang Peng
Keyword(s):  
Frequency Band ◽  
Rotational Speed ◽  
Axial Load ◽  
High Speed ◽  
Ball Bearing ◽  
Structural Vibration ◽  
Optimal Frequency ◽  
Nonlinear Dynamic Model ◽  
Impact Characteristics ◽  
The Impact

The rotational speed is a crucial parameter for bearing condition monitor. The present study shows the influence of the rotational speed on the impact characteristics caused by a localized defect of the outer raceway. A 2 Nb + 5-degrees-of-freedom nonlinear dynamic model for a ball bearing is developed. The waviness of bearing components, a localized defect of the outer raceway, and the centrifugal forces of balls caused by rotational speed are involved in the ball bearing model. Spectral kurtosis (SK) analysis and envelope spectrum analysis are used to extract the impact signal and confirm the position of the optimal frequency band affected by the impact signal. The peak of the impact signal rises with the increase in rotational speed. The position of the optimal frequency band affected by the impact signal is a linear piecewise function of the rotational speed. These simulated results are verified through vibration experiments of a ball bearing with a localized defect of the outer raceway under an axial load. In addition, considering both a localized defect on the outer raceway and the waviness of bearing components, only when the size of the localized defect is large enough, can the impact signal overcome the influence of the structural vibration of the system to extract impact characteristics. The case studies of high-speed spindle bearing state diagnosis show that high speed is not conducive to the extraction of the impact characteristics.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

The Impact of High-Speed Rail on the Spatial Structure of Chinese Urban Agglomerations

2020 ◽  
Vol 46 (3) ◽  
pp. 379-397
Author(s):  
Chunyang Wang
Keyword(s):  
High Speed ◽  
River Delta ◽  
City Size ◽  
High Speed Rail ◽  
Local Conditions ◽  
Urban Agglomerations ◽  
Large Cities ◽  
Spatial Systems ◽  
Economic Concentration ◽  
The Impact

This paper measures the spatial evolution of urban agglomerations to understand be er the impact of high-speed rail (HSR) construction, based on panel data from fi ve major urban agglomerations in China for the period 2004–2015. It is found that there are signi ficant regional diff erences of HSR impacts. The construction of HSR has promoted population and economic diff usion in two advanced urban agglomerations, namely the Yang e River Delta and Pearl River Delta, while promoting population and economic concentration in two relatively less advanced urban agglomerations, e.g. the middle reaches of the Yang e River and Chengdu–Chongqing. In terms of city size, HSR promotes the economic proliferation of large cities and the economic concentration of small and medium-sized cities along its routes. HSR networking has provided a new impetus for restructuring urban spatial systems. Every region should optimize the industrial division with strategic functions of urban agglomeration according to local conditions and accelerate the construction of inter-city intra-regional transport network to maximize the eff ects of high-speed rail across a large regional territory.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

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