scholarly journals Influence of Geometric Parameters on Aerodynamic and Acoustic Performances of Bladeless Fans

2019 ◽  
Author(s):  
Ang Li ◽  
Jun Chen ◽  
Yangfan Liu ◽  
Stuart Bolton ◽  
Patricia Davies
Keyword(s):  
Cross Section ◽  
Fluid Dynamic ◽  
Geometric Parameters ◽  
Design Stage ◽  
Air Velocity ◽  
Cross Sectional ◽  
Future Design ◽  
Cross Sectional Profile ◽  
The Cross ◽  
Sectional Profile

Abstract In recent years, the bladeless fan that does not have visible impellers have been widely applied in household appliances. Since the customers are particularly sensitive to noise and the strength of wind generated by the fan, the aerodynamic and acoustic performances of the fan need to be accurately characterized in the design stage. In this study, computational fluid dynamic (CFD) and computational aeroacoustics (CAA) are applied to investigate the performances of different designs of a bladeless fan model. The influence of four parameters, namely the airfoil selection for cross-section of the wind channel, the slit width, the height of cross-section and the location of the slit, is investigated. The results indicate the streamwise air velocity increases significantly by narrowing the outlet, but the noise level increases simultaneously. In addition, the generated noise increases while the height of fan cross-section increases, and a 4mm height of the cross section is optimal for aerodynamic performance. When the slit is closer to the location of maximum thickness, the performances of the bladeless fan increases. Moreover, the performance is not changed significantly by changing the cross-sectional profile. Finally, the optimal geometric parameters are identified to guide the future design of the bladeless fan.

Assessment of the actual shape of the hot-rolled strip cross-section contour. Part 2. Profile Classifier

2020 ◽  
pp. 33-37
Author(s):  
S. M. Belskiy ◽  
◽  
A. N. Shkarin ◽  
V. A. Pimenov ◽  
◽  
...  
Keyword(s):  
Cross Section ◽  
Middle Part ◽  
Characteristic Classes ◽  
Rolled Strip ◽  
Cross Sectional ◽  
Hot Rolled Strip ◽  
Cross Sectional Profile ◽  
Cold Rolled ◽  
Sectional Profile ◽  
Hot Rolled

The geometric parameters describing the features of the crosssectional profile of a hot-rolled strips do not give a complete picture of the flatness acquired by the cold-rolled strips rolled from these strips. An additional analysis, the results of which are presented in Message 1, showed that there are four characteristic classes of cross-sectional profiles of hot rolled strips that have a significant effect on the shape of the strips during cold rolling, three of which negatively affect the flatness of the cold rolled strips. The cross-sectional profiles of hot-rolled strips with a concave middle part and / or marginal thickenings lead to the appearance of edge waviness, peak-like cross-sectional profiles cause central warping. Therefore, the actual task is to determine the factual shape of cross-sectional profile. 6th order polynomials were used to digitalize and parameterize hot-rolled profile. As a result, we developed analytic function of the transverse profile, which keeps important information about its near-edge areas and features in the middle part. To assign a specific crosssectional profile of a hot-rolled strip to one of four characteristic classes of cross-sections, mathematical software was developed, called a classifier, and implemented with the programming environment R. To classify the profiles of the hot-rolled cross-section according to characteristic classes, a linear discriminant method was used as a machine learning method analysis. The result is an adequate mathematical model for recognizing the shape of the cross-sectional profile. The study was carried out with the financial support of the Russian Foundation for Basic Research within the framework of scientific project No. 19-38-90257.

Rational design of capillary-driven flows for paper-based microfluidics

Lab on a Chip ◽  
2015 ◽  
Vol 15 (10) ◽  
pp. 2173-2180 ◽  
Author(s):  
Emanuel Elizalde ◽  
Raúl Urteaga ◽  
Claudio L. A. Berli
Keyword(s):  
Flow Rate ◽  
Rational Design ◽  
Front Velocity ◽  
Cross Sectional ◽  
Liquid Front ◽  
Paper Based Microfluidics ◽  
Cross Sectional Profile ◽  
The Cross ◽  
Sectional Profile ◽  
Paper Substrates

We present a tool that allows one to determine the cross-sectional profile required for a programmed liquid front velocity or flow rate during lateral imbibition in paper substrates. New regimes can be designed, i.e. constant liquid front velocity.

Rapid motions of free-surface avalanches down curved and twisted channels and their numerical simulation

2005 ◽  
Vol 363 (1832) ◽  
pp. 1551-1571 ◽  
Author(s):  
Shiva P Pudasaini ◽  
Yongqi Wang ◽  
Kolumban Hutter
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Circular Cross Section ◽  
Hyperbolic Partial Differential Equations ◽  
Finite Mass ◽  
Governing Equations ◽  
Cross Sectional ◽  
Variation Diminishing ◽  
Cross Sectional Profile ◽  
Sectional Profile

This paper presents a new model and discussions about the motion of avalanches from initiation to run-out over moderately curved and twisted channels of complicated topography and its numerical simulations. The model is a generalization of a well established and widely used depth-averaged avalanche model of Savage & Hutter and is published with all its details in Pudasaini & Hutter (Pudasaini & Hutter 2003 J. Fluid Mech. 495 , 193–208). The intention was to be able to describe the flow of a finite mass of snow, gravel, debris or mud, down a curved and twisted corrie of nearly arbitrary cross-sectional profile. The governing equations for the distribution of the avalanche thickness and the topography-parallel depth-averaged velocity components are a set of hyperbolic partial differential equations. They are solved for different topographic configurations, from simple to complex, by applying a high-resolution non-oscillatory central differencing scheme with total variation diminishing limiter. Here we apply the model to a channel with circular cross-section and helical talweg that merges into a horizontal channel which may or may not become flat in cross-section. We show that run-out position and geometry depend strongly on the curvature and twist of the talweg and cross-sectional geometry of the channel, and how the topography is shaped close to run-out zones.

scholarly journals Cause of Angular Distortion in Fusion Welding: Asymmetric Cross-Sectional Profile along Thickness

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 58 ◽  
Author(s):  
Deqiao Xie ◽  
Jianfeng Zhao ◽  
Huixin Liang ◽  
Shuang Liu ◽  
Zongjun Tian ◽  
...  
Keyword(s):  
Cross Section ◽  
Fusion Welding ◽  
Angular Distortion ◽  
Cross Sectional ◽  
Section Profile ◽  
Cross Sectional Profile ◽  
The Asymmetry ◽  
The Difference ◽  
Sectional Profile ◽  
Cross Section Profile

Angular distortion is a common problem in fusion welding, especially when it comes to thick plates. Despite the fact that various processes and influencing factors have been discussed, the cause of the angular distortion has not been clearly revealed. In this research, the asymmetry of cross-sectional profile along thickness is considered of great importance to the angular distortion. A theoretical model concerning the melting-solidification process in fusion welding was established. An expression of the angular distortion was formulated and then validated by experiments of laser welding 316L stainless steel. The results show that the asymmetric cross-sectional profile is a major contributory factor towards the angular distortion mechanism. The asymmetry of cross-section profile along thickness causes the difference between two bending moments in the lower and upper parts of the joint. This is the difference that drives the angular distortion of the welded part. Besides, the asymmetry of cross-section profile is likely to be influenced by various processes and parameters, thereby changing the angular distortion.

scholarly journals Maximizing friction in the erosion of glacial valleys

2020 ◽  
Vol 66 (259) ◽  
pp. 876-879 ◽  
Author(s):  
Valerio Faraoni
Keyword(s):  
Variational Principle ◽  
Cross Sectional ◽  
Cross Sectional Profile ◽  
The Cross ◽  
Sectional Profile

AbstractThe cross-sectional profile of a glacial valley can be obtained with a variational principle in which the friction against the valley walls and the glacier bed is extremized, subject to a Lagrangian constraint. We show that the actual valley profile maximizes the friction, thus settling an old debate.

Topology Synthesis of Extrusion-Based Nonlinear Transient Designs

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Neal M. Patel ◽  
Charles L. Penninger ◽  
John E. Renaud
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Optimization Methods ◽  
Constant Cross Section ◽  
Cross Sectional ◽  
Design Concepts ◽  
Nonlinear Transient ◽  
Cross Sectional Profile ◽  
Sectional Profile ◽  
Finishing Processes

Many practical structural designs require that the structure is easily manufactured. Design concepts synthesized using conventional topology optimization methods are typically not easily manufactured, in that multiple finishing processes are required to construct the component. A manufacturing technique that requires only minimal effort is extrusion. Extrusion is a manufacturing process used to create objects of a fixed cross-sectional profile. The result of using this process is lower costs for the manufacture of the final product. In this paper, a hybrid cellular automaton algorithm is developed to synthesize constant cross section structures that are subjected to nonlinear transient loading. The novelty of the proposed method is the ability to generate constant cross section topologies for plastic-dynamic problems since the issue of complex gradients can be avoided. This methodology is applied to extrusions with a curved sweep along the direction of extrusion as well. Three-dimensional examples are presented to demonstrate the efficiency of the proposed methodology in synthesizing these structures. Both static and dynamic loading cases are studied.

scholarly journals Effects of the Extrusion Process Parameter

2011 ◽  
Vol 8 (1) ◽  
pp. 65-74
Author(s):  
Prashant Baredar ◽  
Jitendra Kumar ◽  
Anil Kumar ◽  
Shankar Kumar
Keyword(s):  
Plastic Deformation ◽  
Cross Section ◽  
Cross Sections ◽  
Metal Forming ◽  
Extrusion Process ◽  
Cross Sectional ◽  
High Deformation ◽  
Tensile Forces ◽  
Cross Sectional Profile ◽  
Sectional Profile

Extrusion is an important Metal forming operation. It is a manufacturing process used to create long objects of a fixed cross sectional profile. The extrusion process is based on the plastic deformation of a material due to compressive and shears forces only. No tensile forces are applied to the extruded metal. The latter allows the material to withstand high deformation without tearing out the material. Basically, this procedure is based on the reducing and shaping the cross section of piece of metal squeezing the material through an orifice or a die. Typically the blocks of metal used for this procedure are long straight parts with circular cross sections.

Deterministic Process Modelling of Micro Air Abrasive Jet Machining of Glass Channel

2010 ◽  
Vol 447-448 ◽  
pp. 272-276 ◽  
Author(s):  
Stephen Wan ◽  
Weng Seng Fong ◽  
Qi Ying Leong
Keyword(s):  
Erosive Wear ◽  
Soda Lime ◽  
Process Models ◽  
Machining Process ◽  
Cross Sectional ◽  
Deterministic Process ◽  
Abrasive Jet Machining ◽  
Cross Sectional Profile ◽  
The Cross ◽  
Sectional Profile

We present simple deterministic process models for the prediction of the evolution of the cross-sectional profile of glass channels generated by erosive wear in micro air abrasive jet machining using a round nozzle. The present work was motivated by a need to understand the sensitivity of the geometry of the generated cross-sectional profile to the degree of offset between the centre of the nozzle and the centre of the mask defining the channel. Experiments were carried out on soda lime and borosilicate glass to verify the process models. Predicted results show fairly good agreement with experimental results. We conclude that, without proper alignment, the cross-sectional profile is easily skewed, as the micro abrasive jet machining process quickly acts on any initial geometrical skewness and compounds it over time.

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