scholarly journals Analytical model for electrohydrodynamic thrust

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200220
Author(s):  
Ravi Sankar Vaddi ◽  
Yifei Guan ◽  
Alexander Mamishev ◽  
Igor Novosselov
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Momentum Transfer ◽  
Analytical Model ◽  
First Principles ◽  
Thrust Force ◽  
Propulsion Systems ◽  
One Dimensional ◽  
Charged Species ◽  
Good Agreement

Electrohydrodynamic (EHD) thrust is produced when ionized fluid is accelerated in an electric field due to the momentum transfer between the charged species and neutral molecules. We extend the previously reported analytical model that couples space charge, electric field and momentum transfer to derive thrust force in one-dimensional planar coordinates. The electric current density in the model can be expressed in the form of Mott–Gurney law. After the correction for the drag force, the EHD thrust model yields good agreement with the experimental data from several independent studies. The EHD thrust expression derived from the first principles can be used in the design of propulsion systems and can be readily implemented in the numerical simulations.

scholarly journals A thermodynamic description of metastable c-TiAlZrN coatings with triple spinodally decomposed domains

2017 ◽  
Vol 53 (2) ◽  
pp. 85-93 ◽  
Author(s):  
J. Zhou ◽  
L. Zhang ◽  
L. Chen ◽  
Y. Du ◽  
Z.K. Liu
Keyword(s):  
Experimental Data ◽  
Phase Equilibria ◽  
First Principles ◽  
Thermodynamic Description ◽  
Quantitative Description ◽  
Experimental Phase Equilibria ◽  
Free Energies ◽  
Calphad Technique ◽  
Important Input ◽  
Good Agreement

A critical thermodynamic assessment of the metastable c-TiAlZrN coatings, which are reported to spinodally decompose into triple domains, i.e., c-TiN, c-AlN, and c-ZrN, was performed via the CALculation of PHAse Diagram (CALPHAD) technique based on the limited experimental data as well as the first-principles computed free energies. The metastable c-TiAlZrN coatings were modeled as a pseudo-ternary phase consisting of c-TiN, c-AlN and c-ZrN species, and described using the substitutional solution model. The thermodynamic descriptions for the three boundary binaries were directly taken from either the CALPHAD assessment or the first-principles results available in the literature except for a re-adjustment of the pseudo-binary c-AlN/c-ZrN system based on the experimental phase equilibria in the pseudo-ternary system. The good agreement between the calculated phase equilibria and the experimental data over the wide temperature range was obtained, validating the reliability of the presently obtained thermodynamic descriptions for the c-TiAlZrN system. Based on the present thermodynamic description, different phase diagrams and thermodynamic properties can be easily predicted. It is anticipated that the present thermodynamic description of the metastable c-TiAlZrN coatings can serve as the important input for the later quantitative description of the microstructure evolution during service life.

scholarly journals Wave Propagation in Thin-Walled Aortic Analogues

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
C. G. Giannopapa ◽  
J. M. B. Kroot ◽  
A. S. Tijsseling ◽  
M. C. M. Rutten ◽  
F. N. van de Vosse
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Frequency Domain ◽  
Analytical Model ◽  
Viscoelastic Properties ◽  
Numerical Models ◽  
Computational Cost ◽  
One Dimensional ◽  
Arterial Blood

Research on wave propagation in liquid filled vessels is often motivated by the need to understand arterial blood flows. Theoretical and experimental investigation of the propagation of waves in flexible tubes has been studied by many researchers. The analytical one-dimensional frequency domain wave theory has a great advantage of providing accurate results without the additional computational cost related to the modern time domain simulation models. For assessing the validity of analytical and numerical models, well defined in vitro experiments are of great importance. The objective of this paper is to present a frequency domain analytical model based on the one-dimensional wave propagation theory and validate it against experimental data obtained for aortic analogs. The elastic and viscoelastic properties of the wall are included in the analytical model. The pressure, volumetric flow rate, and wall distention obtained from the analytical model are compared with experimental data in two straight tubes with aortic relevance. The analytical results and the experimental measurements were found to be in good agreement when the viscoelastic properties of the wall are taken into account.

scholarly journals Response of a Warped Flexible Rotor with a Fluid Bearing

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Jim Meagher ◽  
Xi Wu ◽  
Chris Lencioni
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Equation Of Motion ◽  
Diagnostic Information ◽  
Flexible Rotor ◽  
Vibration Data ◽  
Rotor Model ◽  
Good Agreement

A two-complex-degrees-of-freedom model is developed and compared to experimental data for various amounts of rotor bow and its orientation to mass imbalance of the rotor. The equation of motion is developed by adding constant forces that rotate with the rotor to a Bently-Muszynska two-mode isotropic rotor model with a plane journal bearing. Diagnostic information discernable from probes at the bearing is explored and compared to midspan response, where previous research has concentrated. The model presented also extends earlier work by representing the effect of a nonrigid bearing. Good agreement between the analytical model and experiment demonstrates that the analysis presented can be useful to diagnose and balance residual shaft bow from probes located at the bearings, where vibration data are typically more available than midspan probes.

scholarly journals Modelling of a low-temperature differential Stirling engine

2007 ◽  
Vol 221 (8) ◽  
pp. 927-943 ◽  
Author(s):  
A Robson ◽  
T Grassie ◽  
J Kubie
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Low Temperature ◽  
First Principles ◽  
Dynamic Behaviour ◽  
Stirling Engine ◽  
Current Paper ◽  
Temperature Differential ◽  
Good Agreement

A full theoretical model of a low-temperature differential Stirling engine is developed in the current paper. The model, which starts from the first principles, gives a full differential description of the major components of the engine: the behaviour of the gas in the expansion and the compression spaces; the behaviour of the gas in the regenerator; the dynamic behaviour of the displacer; and the power piston/flywheel assembly. A small fully instrumented engine is used to validate the model. The theoretical model is in good agreement with the experimental data, and describes well all features exhibited by the engine.

scholarly journals Wave Propagation in Thin-Walled Aortic Analogues

2008 ◽  
Author(s):  
C. G. Giannopapa ◽  
J. M. B. Kroot
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Frequency Domain ◽  
Analytical Model ◽  
Viscoelastic Properties ◽  
Numerical Models ◽  
Computational Cost ◽  
Arterial Blood Flow ◽  
One Dimensional ◽  
Arterial Blood

Research wave propagation in liquid filled vessels is often motivated by the need to understand arterial blood flow. Theoretical and experimental investigation of the propagation of waves in flexible tubes has been studied by many researchers. The analytical one dimensional frequency domain wave theory has a great advantage of providing accurate results without the additional computational cost related to the modern time domain simulation models. For assessing the validity of analytical and numerical models well defined in-vitro experiments are of great importance. The objective of this paper is to present a frequency domain transmission line analytical model based on one-dimensional wave propagation theory and validate it against experimental data obtained for aortic analogues. The elastic and viscoelastic properties of the wall are included in the analytical model. The pressure, flow and wall distention results obtained from the analytical model are compared with experimental data in two straight tubes with aortic relevance. The analytical models and the experimental measurements were found to be in good agreement when the viscoelastic properties of the wall are taken into account.

A Simple Analytical Model to Simulate Oblique Ballistic Impact onto Fabric

2011 ◽  
Vol 110-116 ◽  
pp. 3453-3458
Author(s):  
Mohamad Ali Akbari ◽  
Golam Hosein Liaghat ◽  
Hadi Sabouri
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Ballistic Impact ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Good Agreement

A simple analytical model for oblique ballistic impact of projectiles into fabrics are presented. This model is extension of Chocron-Benloulo penetration model. Results are compared with experimental data. There is good agreement between analytical and experimental results.

Performance Analysis and Optimization of a Dual Warhead System

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiao-Jun Guo ◽  
He-Ming Wen
Keyword(s):  
Experimental Data ◽  
Performance Analysis ◽  
Analytical Model ◽  
Present Model ◽  
Shaped Charge ◽  
Weapon Systems ◽  
Model Predictions ◽  
Modern Warfare ◽  
Good Agreement ◽  
Concrete Target

AbstractIn modern warfare earth penetrating weapons are often used to defeat enemy’s hardened and deeply buried targets such as aircraft shelters and bunkers. A dual warhead system (DWS) is one of such weapons composed of a forward shaped charge (FSC) and a following through warhead (FTW). In this paper, an analytical model is first proposed to analyze the penetration of an FTW into concrete targets with pre-drilled holes and a DWS is then optimized in order to achieve its best penetration performance. The effects of various parameters on the performance of a dual warhead system penetrating a concrete target are delineated. It transpires that the present model predictions are in good agreement with available experimental data and that the results obtained may be useful for designing such weapon systems.

scholarly journals Time-Fractional Model of Chloride Diffusion in Concrete: Analysis Using Meshless Method

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Ling Yao ◽  
Lixia Ren ◽  
Guoli Gong
Keyword(s):  
Experimental Data ◽  
Meshless Method ◽  
Model Simulation ◽  
Order Equation ◽  
Chloride Diffusion ◽  
Fractional Model ◽  
One Dimensional ◽  
Element Free Galerkin ◽  
Element Free ◽  
Good Agreement

Chloride diffusion is the major factor that affects the life of concrete structures. The time-fractional order equation can be used to describe anomalous diffusion in reinforced concrete. In this work, a time-fractional model of chloride diffusion is solved via the meshless method. The Element-Free Galerkin (EFG) meshless method does not require meshing. One-dimensional and two-dimensional numerical examples are presented. Numerical results are in good agreement with theoretical solutions. The initiation time of corrosion is predicted in the presented model. Simulation results are compared with experimental data. The good agreement between EFG and experimental data indicates that time-fractional chloride diffusion in concrete can be modeled effectively by using the EFG method. This method is beneficial for further research on anomalous chloride diffusion in concrete.

Dynamics Analytical Model of Cutting Force in Metal Cutting Processing

2011 ◽  
Vol 308-310 ◽  
pp. 1211-1214
Author(s):  
Jian Ying Guo ◽  
Wen Bin Li ◽  
Shi Ying Wang ◽  
Ming Lv
Keyword(s):  
Experimental Data ◽  
Cutting Force ◽  
Analytical Model ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Static Balance ◽  
Impact Effect ◽  
New Formula ◽  
Suggested Formula ◽  
Good Agreement

Cutting force is an important parameter in machining. The static balance method and experience formulas had been adopted to find its value, but the theoretical calculated value is not good agreement with the experimental value for the same set of cutting conditions. In practical machining, the cutting tool has obvious impact effect on workpiece, so a dynamics analytical model for cutting process is established in this paper. Based on the proposed solution, a new formula for cutting force has been obtained. The suggested formula has shown to correspond well with the experimental data.

Electronic and optical properties of ZnSxSe1−x alloys

Open Physics ◽  
2009 ◽  
Vol 7 (2) ◽  
Author(s):  
Zhenbao Feng ◽  
Haiquan Hu ◽  
Shouxin Cui
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Band Structure ◽  
Density Of States ◽  
Absorption Edge ◽  
First Principles ◽  
Semiconductor Alloys ◽  
Electronic And Optical Properties ◽  
Spectral Peaks ◽  
Good Agreement

AbstractA series of calculations from first principles have been carried out to study structural, electronic, and optical properties of ZnSxSe1−x alloys. Our results show that the lattice constant scales linearly with sulfur composition. The imaginary parts of the dielectric function are calculated, which are in good agreement with the experimental data. We have also interpreted the origin of the spectral peaks on the basis of band structure and density of states. Additionally, we find that no bowing effect in the absorption edge is observed, unlike other II-VI semiconductor alloys.

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