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Airflow distribution law of multi-branch pipe of pneumatic rice direct seeder based on Dimensional analysis

International Journal of Agricultural and Biological Engineering 2023年第1期16卷 111-127页

作者： Wei Qin Zaiman Wang Minghua Zhang Siyu He Xuguo Wang Youcong Jiang Zishun Huang Ying Zang Guangdong Laboratory for Lingnan Modern Agriculture College of EngineeringSouth China Agricultural UniversityGuangzhou510642China Key Laboratory of Key Technology on Agricultural Machine and Equipment(South China Agricultural University) Ministry of EducationGuangzhou 510642China Guangdong Provincial Key Laboratory of Agricultural Artificial Intelligence(GDKL-AAI) Guangzhou 510642China Huangpu Innovation Research Institute of SCAU Guangzhou 510715China Maoming Branch Guangdong Laboratory for Modern AgricultureMaoming 525000GuangdongChina

In order to investigate the flow characteristics and distribution law of airflow in multi-branch pipe of pneumatic rice precision direct seeder and obtain the mathematical model between airflow parameters and pipe geometry structure.In this study,the airflow flow law of the multi-branch pipeline of the pneumatic system was studied,the mechanism of airflow flow in the multi-branch pipe was analyzed,and it was clarified that the main factors affecting the airflow flow in the pipe,namely,air density,air dynamic viscosity,the total flow rate of the inlet branch pipe,the length of the closed end of the header,the inner diameter of the outlet branch pipe,and the outlet branch pipe spacing.Numerical simulations were carried out using Fluent simulation software to elucidate the cause of multi-branch pipes of uneven distribution of airflow in multi-branch pipes,the empirical equation among these factors and the flow velocity of the outlet branch pipe are established by Dimensional analysis method.The bench test results show that the established empirical equations are applicable in the following ranges:0.018 m3/s≤Q≤0.054 m3/s,0.045 m≤d≤0.05 m,0.075 m≤L≤0.125 m,0.7 m≤Y 1≤0.875 m(0.5 m≤Y 2≤0.75 m,0.36 m≤Y 3≤0.45 m),the prediction accuracy can be controlled within 10%of the empirical formula,which can provide a reference for the prediction and optimization design of outlet velocity of the multi-branch pipe.

关键词： pneumatic system multi-branch pipe axial momentum conservation Fluent Dimensional analysis

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Parametric Dimensional analysis on the Structural Response of An Innovative Subsurface Tension Leg Platform in Ultra-Deep Water

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China Ocean Engineering 2018年第4期32卷 482-489页

作者： ZHEN Xing-wei WU Jia-hao HUANG Yi HAN Yue YAO Jin-jiang School of Naval Architecture and Ocean Engineering Faculty of Vehicle Engineering and Mechanics Dalian University of Technology

The innovative Subsurface Tension Leg Platform(STLP), which is designed to be located below Mean Water Level(M.W.L) to minimize direct wave loading and mitigate the effect of strong surface currents, is considered as a competitive alternative system to support shallow-water rated well completion equipment and rigid risers for large ultra-deep water oil field development. A detailed description of the design philosophy of STLP has been published in the series of papers and patents. Nonetheless, design uncertainties arise as limited understanding of various parameters effects on the structural response of STLP, pertaining to the environmental loading, structural properties and hydrodynamic characteristics. This paper focuses on providing quantitative methodology on how each parameter affects the structural response of STLP, which will facilitate establishing the unique design criteria as regards to STLP. Firstly, the entire list of dimensionless groups of input and output parameters is proposed based on VaschyBuckingham theory. Then, numerical models are built and a series of numerical tests are carried out for validating the obtained dimensionless groups. On this basis, the calculation results of a great quantity of parametric studies on the structural response of STLP are presented and discussed in detail. Further, empirical formulae for predicting STLP response are derived through nonlinear regression analysis. Finally, conclusions and discussions are made. It has been demonstrated that the study provides a methodology for better control of key parameters and lays the foundation for optimal design of STLP. The obtained conclusions also have wide ranging applicability in reference to the engineering design and design analysis aspects of deepwater buoy supporting installations, such as Grouped SLOR or TLR system.

关键词： subsurface tension leg platform structural response Dimensional analysis ultra-deep water

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Dimensional analysis of earthquake-induced pounding between adjacent inelastic MDOF buildings

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 295-313页

作者： Zhai Changhai Jiang Shan Li Shuang Xie Lili School of Civil Engineering Harbin Institute of Technology Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration

In this study the seismic pounding response of adjacent multi-degree-of-freedom(MDOF) buildings with bilinear inter-story resistance characteristics is investigated through Dimensional analysis. The application of Dimensional analysis leads to a condensed presentation of the response, and the remarkable self-similarity property for bilinear MDOF buildings with inelastic collision is uncovered. It is shown that when the response is expressed in the appropriate dimensionless form, response spectra for any intensity of the excitation collapse to a single master curve. The reduced Π set explicitly describes the interaction between the colliding structures. The effect of pounding on the MDOF building’s response is illustrated using three well-divided spectral regions(amplifi ed, de-amplifi ed and unaffected regions). Parametric studies are conducted to investigate the effects of the story stiffness of structures, the story stiffness ratio and mass ratio of adjacent buildings, the structural inelastic characteristics and the gap size values. Results show that(i) the infl uence of system stiffness ratio to the lighter and more fl exible building is more signifi cant in the fi rst spectral region, where the maximum response of the building is amplifi ed because of pounding; and(ii) the velocity and pounding force of the heavier and stiffer building is unexpectedly sensitive to the mass ratio of adjacent buildings.

关键词： pounding Dimensional analysis earthquake engineeri

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Dimensional analysis and extended hydrodynamic theory applied to long-rod penetration of ceramics

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Defence Technology（防务技术） 2016年第4期12卷 334-342页

作者： J.D.CLAYTON Impact Physics RDRL-WMP-C US Army Research Laboratory Aberdeen Proving Ground A.James Clark School of Engineering University of Maryland College Park

Principles of Dimensional analysis are applied in a new interpretation of penetration of ceramic targets subjected to hypervelocity impact. The analysis results in a power series representation – in terms of inverse velocity – of normalized depth of penetration that reduces to the hydrodynamic solution at high impact velocities. Specifically considered are test data from four literature sources involving penetration of confined thick ceramic targets by tungsten long rod projectiles. The ceramics are AD-995 alumina, aluminum nitride, silicon carbide, and boron carbide.Test data can be accurately represented by the linear form of the power series, whereby the same value of a single fitting parameter applies remarkably well for all four ceramics. Comparison of the present model with others in the literature(e.g., Tate's theory) demonstrates a target resistance stress that depends on impact velocity, linearly in the limiting case. Comparison of the present analysis with recent research involving penetration of thin ceramic tiles at lower typical impact velocities confirms the importance of target properties related to fracture and shear strength at the Hugoniot Elastic Limit(HEL) only in the latter. In contrast, in the former(i.e., hypervelocity and thick target) experiments, the current analysis demonstrates dominant dependence of penetration depth only by target mass density. Such comparisons suggest transitions from microstructure-controlled to density-controlled penetration resistance with increasing impact velocity and ceramic target thickness.Production and hosting by Elsevier B.V. on behalf of China Ordnance Society.

关键词： Ceramics Terminal ballistics Armor Dimensional analysis Hydrodynamics

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Material Equivalent Test Based on Dimensional analysis for Fragment Penetrating Antenna Target

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Journal of Donghua University(English Edition) 2016年第2期33卷 206-209页

作者：刘锋石全陈材 Department of Equipment Command and Management Mechanical Engineering College

Phased array radar is the main sensor in a battlefield.Phased array antenna is the main execution unit of the phased array radar,and it greatly affects the reliability of the phased array radar. As a result,the fragment damaged antenna test is important.As the materials of phased array antenna are not easy to get,the fragment damaged antenna test is difficult to carry out. Then we present a study on this problem and introduce the principles of Dimensional analysis to solve it. Firstly, the fragments damage antenna target dimensionless model is constructed. Secondly,the finite element analysis software ANSYS / LS-DYNA are used to carry out a large number of different materials simulation test for Dimensional analysis. Finally,based on dimensional test analysis,the materials equivalent empirical model between different antennas target is presented in the same damage. The results of this study provide a feasible and valuable solution for different materials' target damaged test.

关键词： fragments phased array antenna Dimensional analysis material equivalent

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Magnetic field assisted fluidization—Dimensional analysis addressing the physical basis

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China Particuology 2007年第1期5卷 103-110页

作者： Jordan Hristov Department of Chemical Engineering University of Chemical Technology and Metallurgy Sofia 1756 8 "Kliment Ohridsky" Boulevard Bulgaria

This paper originates a discussion on Dimensional analysis and scaling in magnetically assisted fluidized beds. Basic examination of process variables, merging mechanical and magnetic units, allows the conversion of mixed sets of variables into unified terms representing surface forces as effects of the fields contributing to the assisted fluidization behaviour. This transformation is termed ＂pressure transform＂ since the new variables are all characteristic pressures generated by three basic fields： gravity, magnetic and fluid flow. This approach addresses the physical basis in terms of dimensionless groups rather than formal algebraic manipulations pertinent to classical Dimensional analysis. Basic dimensionless group termed granular magnetic Bond number is introduced as the ratio of characteristic pressures of gravity and of magnetic field. This analysis also provides a set of named dimensionless numbers characterizing magnetic field assisted fluidization such as Filippov number, Rosensweig number, Kwauk number and Siegell number, derived as ratios of characteristic pressures.

关键词： Magnetic field assisted fluidization （MFAF） Dimensional analysis Bond number

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Process analysis for an alfalfa rotary dryer using an improved Dimensional analysis method

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International Journal of Agricultural and Biological Engineering 2009年第3期2卷 76-82页

作者： Zheng Xianzhe Yubin Lan Wang Jianying Dong Hangfei College of Engineering Northeast Agricultural UniversityHarbin150030China Areawide Pest Management Research Unit United States Department of Agriculture–Agricultural Research ServiceCollege StationTX 77845USA

All parameters in terms of wet alfalfa input capacity,dry alfalfa output capacity,alfalfa stem length,rotary speed,heated air temperature,air flow velocity and number of lifting flights fixed at the interior wall of rotary dryer were integrated and derived into fourπterms based on Jiang’s principle.The drying temperature was a significant factor influencing the drying rate and the post-drying quality of alfalfa hay.An improved G.Murphy theorem with high confidence was used to design an experimental program for alfalfa drying in a rotary dryer.Aπequation was derived by using the multiplication of component equations involving the drying parameters and most of its correlation coefficients were higher than 0.99.The validation results show that most of the relative errors ofπterms were lower than 10%and are acceptable in engineering practice.This empirical equation may be used to investigate the parameter interactive effects on conveyor performance,which may be useful in the design and selection of rotary dryers for drying alfalfa hay.

关键词： alfalfa drying rotary dryer Dimensional analysis

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Quantifying.Associations among Dimensions of Ears and Their Form Factors in Maize(Zea Mays)Using Dimensional analysis

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Agricultural Science & Technology 2016年第10期17卷 2287-2292页

作者： Hongbo CAO Gaimei LIANG Jinzhong YANG Qingdao Agricultural University/Shandong Provincial Key Laboratory of Dry Farming Techniques Qingdao 266109China Shanxi Academy of Agricultural Sciences Shanxi 030006China

Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars were collected from field experiments, and ear length(L), diameter(D), area(S) and volume(V) were recorded for individual ears, kernel weight per ear also recorded for a portion of the examined ears. Following principles of Dimensional analysis, 8 theoretical equations of 3 sets,which relate ear higher dimensions to its length and diameter, were developed and parameterized and validated with the field observations. The 3 optimized equations showed that the shape of ears in maize can be featured with 3 dimensionless form factors, namely diameter-to-length ratio(c=D/L), areal form factor(b=S/L/D), and volumetric form factor(a=V/L/D/D). Statistically,all of them were significantly different among cultivars, and a's values varied from 0.582 to 0.612, and b's 0.839-0.868, and c's 0.242-0.308. Volumetric form factor and areal form factor could estimate precisely ear volume and area respectively, but diameter-to-length ratio was not suitable to estimate ear diameter by its length. Ear volume explained almost all variation of ear kernel weight and product L*D*D did the same substantially. Dimensional analysis proved to be promising in understanding relationship among morphological traits of ears in maize. Its application in crop researches should improve our knowledge of the physical properties of crop plants.

关键词： Maize(Zea Mays) Dimensional analysis Ear shape Volumetric form factors Ear volume Diameter-to-length ratio Ear kernel weight

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Estimation on Flux and Power Consumption of Twin Screw Pulping Extruder Based on Dimensional analysis

Estimation on Flux and Power Consumption of Twin Screw Pulpi...

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2011 International Conference on Advanced Materials and Computer Science(ICAMCS 2011)

作者： Ping WANG Konghui GUO Zhou LAN Dongkui HU College of Mechanical Engineering Tianjin University of Science ＆ Technology

Formulas of flux and power consumption of twin screw pulping extruder（TSPE） based on extrusion model deal with nearly all of geometrical and mechanical parameters of the twin screw and the material processed, they are not convenient for estimation and initial design of the machine. Adopting Dimensional analysis based on similarity theory and considering the most important factors, such as outer diameter of screw, rotational speed of screw and average pressure between barrel and material processed, estimation equations of flux and power consumption of the TSPE are deduced in the paper, and the correction coefficients are determined by experiment data. The estimation results show that the estimation and theoretical results have similar changeable trend although there are some errors. The work is easy to apply in the estimation and initial design of the TSPE, and complement the design theory and method of the TSPE.

关键词： flux power consumption twin screw pulping extruder Dimensional analysis

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Blast wave characteristics of multi-layer composite charge:Theoretical analysis,numerical simulation,and experimental validation

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Defence Technology（防务技术） 2023年第1期19卷 91-102页

作者： Jun-bao Li Wei-bing Li Xiao-wen Hong Jia-xin Yu Jian-jun Zhu ZNDY of Ministerial Key Laboratory Nanjing University of Science and TechnologyNanjing210094China Inner Mongolia Metal Material Research Institute Yantai264003China China Ship Development and Design Center Wuhan 430064China

This article investigates the characteristics of shock wave overpressure generated by multi-layer composite charge under different detonation modes.Combining Dimensional analysis and the explosion mechanism of the charge,a peak overpressure prediction model for the composite charge under singlepoint detonation and simultaneous detonation was established.The effects of the charge structure and initiation method on the overpressure field characteristics were investigated in AUTODYN simulation.The accuracy of the prediction model and the reliability of the numerical simulation method were subsequently verified in a series of static explosion experiments.The results reveal that the mass of the inner charge was the key factor determining the peak overpressure of the composite charge under single-point detonation.The peak overpressure in the radial direction improved apparently with an increase in the aspect ratio of the charge.The overpressure curves in the axial direction exhibited a multi-peak phenomenon,and the secondary peak overpressure even exceeded the primary peak at distances of 30D and 40D(where D is the charge diameter).The difference in peak overpressure among azimuth angles of 0-90°gradually decreased with an increase in the propagation distance of the shock wave.The coupled effect of the detonation energy of the inner and outer charge under simultaneous detonation improved the overpressure in both radial and axial directions.The difference in peak overpressure obtained from model prediction and experimental measurements was less than 16.4%.

关键词： Blast wave characteristics Multi-layer composite charge Dimensional analysis AUTODYN mapping Model Explosion experiment

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