scholarly journals Mechanism of Drag Reduction in Floating Plate of Paddy Field Based on CFD

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoze Yu ◽  
Baofeng Zhang ◽  
Jiahan You
Keyword(s):  
Drag Reduction ◽  
Paddy Field ◽  
Optimization Design ◽  
Structural Parameters ◽  
Elevation Angle ◽  
Bottom Surface ◽  
Reduction Mechanism ◽  
Floating Plate ◽  
Vof Model ◽  
Working Resistance

In order to study drag reduction mechanism in mud parts’ operation of surface machine tools for paddy field, this paper takes floating plate, the main working part of laminating mechanism, as the research object and systematically analyzes the mechanism of action of elevation angle, curved angle, penetrating angle, and local microstructure of floating plate on working resistance and local fluid flow characteristics of the laminating structure based on VOF model in Fluent. Using ship mechanics theory and fluid lubrication theory, the drag reduction mechanism under different structural parameters of the floating plate is analyzed. The results show that, compared with the ordinary floating plate, the pressure difference resistance can be reduced by increasing the elevation angle by 60°, curved angle by 20°, and mud separation angle by 20°. The increase of the concave nonsmooth bottom surface structure can reduce viscous frictional resistance, and the total working resistance after structural optimization is comparatively reduced by 48.3%, with lowered hilling height in the forward direction and improved lubrication condition of the bottom surface, forming liquid lubrication effect. This study can provide theoretical references for the optimization design of muddy soil mud parts, mud-machine interaction research, and the development of paddy field laminating mechanism.

Drag Reduction Study about Bird Feather Herringbone Riblets

2013 ◽  
Vol 461 ◽  
pp. 201-205 ◽  
Author(s):  
Hua Wei Chen ◽  
Fu Gang Rao ◽  
De Yuan Zhang ◽  
Xiao Peng Shang
Keyword(s):  
Drag Reduction ◽  
Structural Parameters ◽  
Reduction Rate ◽  
Reduction Mechanism ◽  
Surface Drag ◽  
Flight Feather ◽  
Hollow Shaft ◽  
Smooth Edge ◽  
Bird Feather ◽  
Wild Goose

Flying bird has gradually formed airworthy structures e.g. streamlined shape and hollow shaft of feather to improve flying performance by millions of years natural selection. As typical property of flight feather, herringbone-type riblets can be observed along the shaft of each feather, which caused by perfect alignment of barbs. Why bird feather have such herringbone-type riblets has not been extensively discussed until now. In this paper, microstructures of secondary feathers are investigated through SEM photo of various birds involving adult pigeons, wild goose and magpie. Their structural parameters of herringbone riblets of secondary flight feather are statistically obtained. Based on quantitative analysis of feathers structure, one novel biomimetic herringbone riblets with narrow smooth edge are proposed to reduce surface drag. In comparison with traditional microgroove riblets and other drag reduction structures, the drag reduction rate of the proposed biomimetic herringbone riblets is experimentally clarified up to 15%, much higher than others. Moreover, the drag reduction mechanism of herringbone riblets are also confirmed and exploited by CFD.

scholarly journals Research on Drag Reduction Mechanism and Optimization Design of Bionic Jet Flow

2021 ◽  
Vol 701 (1) ◽  
pp. 012056
Author(s):  
K Chen ◽  
Z G Wei ◽  
Y S Lin ◽  
X F Zhao ◽  
X Qi ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Optimization Design ◽  
Jet Flow ◽  
Reduction Mechanism

Optimal design of a high homogeneous and small-size shim coil for atomic spin gyroscope based on 0-1 linear programming

2020 ◽  
Vol 64 (1-4) ◽  
pp. 165-172
Author(s):  
Dongge Deng ◽  
Mingzhi Zhu ◽  
Qiang Shu ◽  
Baoxu Wang ◽  
Fei Yang
Keyword(s):  
Linear Programming ◽  
Power Consumption ◽  
Low Power ◽  
Optimization Design ◽  
Structural Parameters ◽  
Axial Position ◽  
Low Power Consumption ◽  
Optimal Method ◽  
Atomic Spin ◽  
Shim Coil

It is necessary to develop a high homogeneous, low power consumption, high frequency and small-size shim coil for high precision and low-cost atomic spin gyroscope (ASG). To provide the shim coil, a multi-objective optimization design method is proposed. All structural parameters including the wire diameter are optimized. In addition to the homogeneity, the size of optimized coil, especially the axial position and winding number, is restricted to develop the small-size shim coil with low power consumption. The 0-1 linear programming is adopted in the optimal model to conveniently describe winding distributions. The branch and bound algorithm is used to solve this model. Theoretical optimization results show that the homogeneity of the optimized shim coil is several orders of magnitudes better than the same-size solenoid. A simulation experiment is also conducted. Experimental results show that optimization results are verified, and power consumption of the optimized coil is about half of the solenoid when providing the same uniform magnetic field. This indicates that the proposed optimal method is feasible to develop shim coil for ASG.

scholarly journals Nature-Inspired Structures Applied in Heat Transfer Enhancement and Drag Reduction

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 656
Author(s):  
Zhangyu Zhu ◽  
Juan Li ◽  
Hao Peng ◽  
Dongren Liu
Keyword(s):  
Heat Transfer ◽  
Drag Reduction ◽  
Heat Transfer Enhancement ◽  
Optimization Design ◽  
Pump Energy ◽  
Research Review ◽  
Transfer Enhancement ◽  
Nano Structure ◽  
Transfer Structure ◽  
Biomimetic Structures

Heat exchangers are general equipment for energy exchange in the industrial field. Enhancing the heat transfer of a heat exchanger with low pump energy consumption is beneficial to the maximum utilization of energy. The optimization design for enhanced heat transfer structure is an effective method to improve the heat transfer coefficient. Present research shows that the biomimetic structures applied in different equipment could enhance heat transfer and reduce flow resistance significantly. Firstly, six biomimetic structures including the fractal-tree-like structure, conical column structure, hybrid wetting structure, scale structure, concave-convex structure and superhydrophobic micro-nano structure were summarized in this paper. The biomimetic structure characteristics and heat transfer enhancement and drag reduction mechanisms were analyzed. Secondly, four processing methods including photolithography, nanoimprinting, femtosecond laser processing and 3D printing were introduced as the reference of biomimetic structure machining. Finally, according to the systemic summary of the research review, the prospect of biomimetic heat transfer structure optimization was proposed.

Structural Optimization of the Telescopic Boom of a Certain Type of Truck-Mounted Crane

2014 ◽  
Vol 548-549 ◽  
pp. 383-388
Author(s):  
Zhi Wei Chen ◽  
Zhe Cui ◽  
Yi Jin Fu ◽  
Wen Ping Cui ◽  
Li Juan Dong ◽  
...  
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Cross Sections ◽  
Optimization Design ◽  
Structural Parameters ◽  
Vertical Direction ◽  
Element Model ◽  
Shape Parameters ◽  
Conventional Design ◽  
Design Variables

Parametric finite element model for a commonly used telescopic boom structure of a certain type of truck-mounted crane has been established. Static analysis of the conventional design configuration was performed first. And then an optimization process has been carried out to minimize the total weight of the telescopic structures. The design variables include the geometric shape parameters of the cross-sections and the integrated structural parameters of the telescopic boom. The constraints include the maximum allowable equivalent stresses and the flexure displacements at the tip of the assembled boom structure in both the vertical direction and the circumferential direction of the rotating plane. Compared with the conventional design, the optimization design has achieved a significant weight reduction of up to 24.3%.

Static Characteristics of Gas Foil Thrust Bearing Based on Gas Rarefaction Model

2015 ◽  
Author(s):  
Jiajia Yan ◽  
Guanghui Zhang ◽  
Zhansheng Liu ◽  
Fan Yang
Keyword(s):  
Film Thickness ◽  
Optimization Design ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Rarefied Gas ◽  
Load Capacity ◽  
Structural Parameters ◽  
Lubricating Film ◽  
Lift Off ◽  
Foil Thrust Bearing

A modified Reynolds equation for bump type gas foil thrust bearing was established with consideration of the gas rarefaction coefficient. Under rarefied gas lubrication, the Knudsen number which was affected by the film thickness and pressure was introduced to the Reynolds equation. The coupled modified Reynolds and lubricating film thickness equations were solved using Newton-Raphson Iterative Method and Finite Difference Method. By calculating the load capacity for increasing rotor speeds, the lift-off speed under certain static load was obtained. Parametric studies for a series of structural parameters and assembled clearances were carried out for bearing optimization design. The results indicate that with gas rarefaction effect, the axial load capacity would be decreased, and the lift-off speed would be improved. The rarefied gas has a more remarkable impact under a lower rotating speed and a smaller foil compliance coefficient. When the assembled clearance of the thrust bearing rotor system lies in a small value, the lift-off speed increases dramatically as the assembled clearance decreases further. Therefore, the axial clearance should be controlled carefully in assembling the foil thrust bearing. It’s worth noting that the linear uniform bump foil stiffness model is not exact for large foil compliance ∼0.5, especially for lift-off speed analysis, due to ignoring the interaction between bumps and bending stiffness of the foil.

scholarly journals Multiobjective Optimization Design for Structural Parameters of TBM Disc Cutter Rings Based on FAHP and SAMPGA

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Laikuang Lin ◽  
Yimin Xia ◽  
Dun Wu
Keyword(s):  
Multiobjective Optimization ◽  
Optimization Design ◽  
Structural Parameters ◽  
Rock Breaking ◽  
Ring Structure ◽  
Structure Design ◽  
Disc Cutter ◽  
Load Bearing ◽  
Geological Conditions ◽  
Weight Coefficients

As a key component of tunnel boring machines (TBMs), the disc cutter ring and its structural parameters are closely related to the TBM tunneling quality. Literature review shows that investigations on optimization design methods for cutter ring structure are seriously insufficient. Therefore, in this paper, a multiobjective optimization design model of structural parameters for disc cutter rings is developed based on the complex geological conditions and the corresponding cutter ring structure design requirements. The rock breaking capability, energy consumption, load-bearing capability, wear life, and wear uniformity of disc cutter are selected as the objectives, and the geometric structure of cutter rings, ultimate load-bearing capability, and cutterhead drive performance are determined as constraints. According to the characteristics of this model, a self-adaptive multipopulation genetic algorithm (SAMPGA) is utilized to solve the optimization problem, and the Fuzzy analytical hierarchy process (FAHP) is employed to calculate weight coefficients for multiple objectives. Finally, the applicability of the proposed method is demonstrated through a case study in a TBM project. The results indicated that the rock breaking performance and service life of the disc cutter are improved after optimization by using the proposed method. The utilization of SAMPGA effectively solves the premature local convergence problems during optimization. The geological adaptability should be considered in the cutter ring structure design, which can be realized by using the proposed method based on the suitable weight coefficients.

Finite Element Analysis of the Thermal Field of Piston in an External Combustion Cam Engine

2011 ◽  
Vol 66-68 ◽  
pp. 1240-1244
Author(s):  
Sheng Yao Gao ◽  
De Shi Wang ◽  
Qi Zheng Zhou
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Optimization Design ◽  
Structural Parameters ◽  
Element Model ◽  
Von Mises Stress ◽  
Strength Analysis ◽  
Element Analysis ◽  
Technical Improvement ◽  
External Combustion

As the most dominative component under stress in an external combustion cam engine, the working condition of piston is very rigor. Once new design type and technical improvement is applied, it is necessary to analysis its thermal load and take secure steps. And the finite element model on each conditions of thermal is calculated, which is used to estimate the temperature field and provide a theoretical basis for further structural strength analysis and optimization design. Choosing analysis results of the piston as reference and taking five structural parameters of the piston as design variables, two objective functions including piston mass and maximal Von Mises stress are respectively considered. The optimum design of the piston is executed and the results indicate that it is feasible to improve temperature field and strength of the piston. These results enrich and develop the research on structural analysis and optimization of spatial engine, which are of guiding significance for analyzing engine strength and related problem in theoretically.

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