Numerical Simulation of Convective Heat Transfer in Structured Packed Beds of Particles With Different Particle Contact Treatment Methods

2012 ◽  
Author(s):  
S. S. Bu ◽  
J. Yang ◽  
S. Y. Li ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
Contact Point ◽  
Point Contact ◽  
Treatment Method ◽  
Contact Method ◽  
Packed Beds ◽  
Treatment Methods ◽  
Contact Points ◽  
Flow And Heat Transfer ◽  
Sphere Contact

The treatment of sphere contact is a crucial issue on the numerical analysis of the flow and heat transfer in packed beds of particles. In this work, the effects of three different methods including introducing a gap, area contacting and cylindrically bridging on the flow and heat transfer performances of structured packed beds of particles are investigated with CFD methods. The simulation results have shown that the influence of different treatment methods on the contact point on flow and heat transfer gets greater as the porosity decreases and the Reynolds number increases. There are no large differences among these three methods on the pressure drop and heat transfer under laminar flow regime. Compared with the experimental results, cylindrically bridging method is proved to be reasonable to simplify the sphere–sphere contact points. Therefore, cylindrically bridging treatment method is encouraged to be used instead of point contact method between particles with CFD analysis in structured packed beds of particles.

Wheel-Rail Multi-Point Contact Method for Railway Turnouts

2011 ◽  
Vol 97-98 ◽  
pp. 378-381
Author(s):  
Zhi Wei Chen ◽  
Linan Li ◽  
Shi Gang Sun ◽  
Jun Long Zhou
Keyword(s):  
Calculation Method ◽  
Normal Force ◽  
Contact Point ◽  
Point Contact ◽  
Contact Model ◽  
Contact Method ◽  
Elastic Contact ◽  
Simulation Calculation ◽  
Acute Change

A calculation method of wheel-rail multi-point contact based on the elastic contact model is introduced. Moreover, the simulation calculation of vehicles passing through branch lines of No.18 turnouts is carried out. The result showed that the acute change of wheel-rail normal force caused by the transfers of wheel-rail contact point between two rails can be avoid by wheel-rail multi-point contact method, and the transfers of wheel-rail normal force between two rails is smoother. The validity of wheel-rail multi-point contact method is verified.

Multi-Agent Form Closure Capture of a Generic 2D Polygonal Object Based on Projective Path Planning

2006 ◽  
Author(s):  
Pankaj Sharma ◽  
Anupam Saxena ◽  
Ashish Dutta
Keyword(s):  
Path Planning ◽  
Contact Point ◽  
Point Contact ◽  
Object Boundary ◽  
Actual Object ◽  
Contact Points ◽  
Correct Orientation ◽  
Novel Approach ◽  
Form Closure ◽  
Multi Agent

The study of multi-agent capture and manipulation of an object has been an area of active interest for many researchers. This paper presents a novel approach using Genetic Algorithm to determine the optimal contact points and the total number of agents (mobile robots) required to capture a stationary generic 2D polygonal object. After the goal points are determined the agents then reach their respective goals using a decentralized projective path planning algorithm. Form closure of the object is obtained using the concept of accessibility angle. The object boundary is first expanded and the robots reach the expanded object goal points and then converge on the actual object. This ensures that the agents reach the actual goal points at the same time and have the correct orientation. Frictionless point contact between the object and robots is assumed. The shape of the robot is considered a circle such that it can only apply force in outward radial direction from its center and along the normal to the object boundary at the contact point. Simulations results are presented that prove the effectiveness of the proposed method.

Improved Rotary Contact Method for 5-Axis Sculptured Surfaces Machining

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Wengang Fan ◽  
Peiqing Ye ◽  
Chenxi Fang ◽  
Shaohua Shi
Keyword(s):  
Surface Quality ◽  
Contact Point ◽  
Test Surface ◽  
Contact Method ◽  
Sculptured Surfaces ◽  
Tool Positioning ◽  
Contact Points ◽  
Positioning Strategy ◽  
Cutting Surface ◽  
Cutting Experiment

The 5-axis tool positioning strategy named rotary contact method (RCM) for sculptured surfaces machining has been developed in our previous paper (Fan et al., 2012, “Rotary Contact Method for 5-Axis Tool Positioning,” Trans. ASME J. Manuf. Sci. Eng., 134(2), p. 021004). The RCM finds the optimal tool positions by rotating the tool backward based on the offset surface, and can generate big machined strip width. However, the RCM can only guarantee a contact point because of the design surface's geometric asymmetry in most cases, which leads to the poor surface quality. To resolve this problem, the improved rotary contact method (IRCM) is developed in this paper. The parametric equation of the circular curve of the toroidal cutter defined by the backward and the sideward tilt angle of the tool is strictly deduced. According to the nested optimization of the two tool's angles, there are two contact points found between the tool's cutting surface and the design surface around the feed direction without gouging. Tool positions investigation, machining simulation and cutting experiment are all performed based on a test surface. The results verify the correctness and effectiveness of the IRCM and show that the IRCM can apparently improve the surface quality compared to the RCM.

Effects of Intersection Angles on Flow and Heat Transfer in Corrugated-Undulated Channels With Sinusoidal Waves

2006 ◽  
Vol 128 (8) ◽  
pp. 819-828 ◽  
Author(s):  
Jixiang Yin ◽  
Guojun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Three Dimensional ◽  
Computational Domain ◽  
Straight Channel ◽  
Flow Area ◽  
Contact Points ◽  
Flow And Heat Transfer ◽  
Different Characteristics ◽  
Steady Laminar

This paper reported three-dimensional numerical simulations of the steady laminar flow and heat transfer in corrugated-undulated channels with sinusoidal waves, aiming to investigate the effects of intersection angles (θ) between corrugated and undulated plate and Reynolds number (Re) on the flow and heat transfer. The simulations are conducted by using multi-channel computational domain for three different geometries. The code is validated against experimental results and then data for Nusselt number (Nu) and friction factor (f) are presented in a Re range of 100-1500, and intersection angle range of 30-150deg. The simulation confirms the changes of Nuu (averaged over undulated plate) and Nuc (averaged over corrugated plate) with θ representing different characteristics. As θ increases, Nu (Nuu or Nuc) is about 2–16 times higher for the corrugated-undulated configurations CP-UH1 and CP-UP1 and the concomitant f is about 4–100 higher, when compared to a straight channel having square cross section. The minimum of local Nu ( Nuu or Nuc ) is situated at the four contact points where the top plate touches the bottom one, and the high Nu is located upstream of the crest of the conjugate duct. Performance evaluation for the CP-UH1 channel shows that the goodness factors (G) are larger than 1 with the straight channel having a square cross section as a reference, and the 30deg geometry channel has optimal flow area goodness.

Effect of particle contact point treatment on the CFD simulation of the heat transfer in packed beds

2021 ◽  
Vol 165 ◽  
pp. 242-253
Author(s):  
Mario Pichler ◽  
Bahram Haddadi ◽  
Christian Jordan ◽  
Hamidreza Norouzi ◽  
Michael Harasek
Keyword(s):  
Heat Transfer ◽  
Cfd Simulation ◽  
Contact Point ◽  
Packed Beds ◽  
Particle Contact

scholarly journals Numerical Simulation of Flow and Heat Transfer in Structured Packed Beds with Smooth or Dimpled Spheres at Low Channel to Particle Diameter Ratio

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 937 ◽  
Author(s):  
Shiyang Li ◽  
Lang Zhou ◽  
Jian Yang ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Particle Diameter ◽  
Packed Bed ◽  
Packed Beds ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer

Packed beds are widely used in catalytic reactors or nuclear reactors. Reducing the pressure drop and improving the heat transfer performance of a packed bed is a common research aim. The dimpled structure has a complex influence on the flow and heat transfer characteristics. In the present study, the flow and heat transfer characteristics in structured packed beds with smooth or dimpled spheres are numerically investigated, where two different low channel to particle diameter ratios (N = 1.00 and N = 1.15) are considered. The pressure drop and the Nusselt number are obtained. The results show that, for N = 1.00, compared with the structured packed bed with smooth spheres, the structured packed bed with dimpled spheres has a lower pressure drop and little higher Nusselt number at 1500 < ReH < 14,000, exhibiting an improved overall heat transfer performance. However, for N = 1.15, the structured packed bed with dimpled spheres shows a much higher pressure drop, which dominantly affects the overall heat transfer performance, causing it to be weaker. Comparing the different channel to particle diameter ratios, we find that different configurations can result in: (i) completely different drag reduction effect; and (ii) relatively less influence on heat transfer enhancement.

Kinematic Analysis of a Novel Rimless Wheel With Independently Actuated Spokes

2005 ◽  
Author(s):  
Doug Laney ◽  
Dennis Hong
Keyword(s):  
Contact Point ◽  
Point Contact ◽  
Static Stability ◽  
Advantages And Disadvantages ◽  
Contact Points ◽  
Straight Line ◽  
Wide Range ◽  
Kinematic Analyses ◽  
General Mobility ◽  
The One

One of the major limitations of mobile robots for unstructured environments is their lack of general mobility. Wheeled, treaded, and legged robots each have their advantages and disadvantages, but they all lack the flexibility to be able to cope with a wide range of terrain. The actuated spoke wheel concept is presented in this paper as an alternative locomotive method that allows multiple modes of motion, which give it the ability to stride quickly using one contact point per wheel, walk with static stability with two contact points per wheel, or assume a stable stance using three contact points per wheel. This paper presents the preliminary kinematic analyses of the actuated spoke wheel with no-slip constraints at the ground contacts for a robot using a two actuated spoke wheel configuration. Straight-line motion and considerations for turning are discussed for the one- and two-point contact schemes followed by recommendations for future study.

Sign in / Sign up

Export Citation Format

Share Document