Transient Behavior of a Springless Flapper Valve: Closing Motion

1998 ◽  
Vol 120 (3) ◽  
pp. 678-684
Author(s):  
K. A. Temple ◽  
V. W. Goldschmidt ◽  
J. D. Jones
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Simultaneous Measurement ◽  
Transient Behavior ◽  
Analytical Investigation ◽  
Closing Time ◽  
Model Predictions ◽  
Good Agreement

The closing of a springless flapper valve was investigated in order to gain a better understanding of the transient behavior of the valve. An experimental investigation included simultaneous measurement of pressure and flapper velocity. An analytical investigation included the development of a model to predict the closing of the flapper valve. The flapper closing was experimentally determined to require from 18 to 24 percent of a cycle, and the model predictions were in good agreement with experimental data for the flapper closing time. The present study should be a useful contribution to future modeling of flapper valves and other springless valves.

Viscosity Models Based on Network Theory for Polymer Melts

2010 ◽  
Vol 129-131 ◽  
pp. 1244-1247
Author(s):  
Hai Hang Xu ◽  
Lei Zhong
Keyword(s):  
Experimental Data ◽  
Kinetic Equation ◽  
Constitutive Equation ◽  
Polymer Composites ◽  
Network Theory ◽  
Polymer Melts ◽  
Structure Parameter ◽  
Viscosity Models ◽  
Model Predictions ◽  
Good Agreement

New shear and extensional viscosity models based on Fredrickson kinetic equation coupled with Dewitt constitutive equation were established to predict viscosities of polymer melts. The experimental data of 125°C LDPE and LDPE filled with 35% glass beads reported from references were compared with the model predictions. The predictions showed good agreement with the measurements. The models are simple and easy to use. Because they contain no structure parameter, they are capable to describe the viscosities of pure polymer and polymer composites.

POWER AND EFFICIENCY OF F1-ATPase MOLECULAR MOTOR

2012 ◽  
Vol 11 (01) ◽  
pp. 1240003
Author(s):  
J. M. SANCHO ◽  
RUBEN PEREZ-CARRASCO
Keyword(s):  
Experimental Data ◽  
Angular Velocity ◽  
Molecular Motor ◽  
Transition Rates ◽  
Motor Power ◽  
F1 Atpase ◽  
Flashing Ratchet ◽  
Model Predictions ◽  
Good Agreement ◽  
Ratchet Potential

We present the study of the energetics of the F1-ATPase rotatory molecular motor. The dynamics of this machine are described by a overdamped Langevin equation with a dichotomous flashing ratchet potential whose transition rates are controlled by an analysis of the chemical and physical steps. The model predictions on the observable angular velocity are in good agreement with the experimental data. Inspired by these results we extend our approach to study the energetics of this motor. Power and efficiency are analyzed for different experimental situations which can be tested in experiments.

scholarly journals Modelling the Depth of Jet Penetration in Abrasive Waterjet Contouring of Alumina Ceramics

2004 ◽  
Vol 471-472 ◽  
pp. 462-468
Author(s):  
Jun Wang ◽  
H. Liu ◽  
Chuan Zhen Huang
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Mathematical Models ◽  
Alumina Ceramic ◽  
Abrasive Waterjet ◽  
Alumina Ceramics ◽  
Predictive Capability ◽  
Jet Penetration ◽  
Good Agreement

Predictive mathematical models for the depth of jet penetration are presented for both straight-slit cutting and contouring by an abrasive waterjet (AWJ). The plausibility and predictive capability of the models are assessed and verified by an experimental investigation when cutting an 87% alumina ceramic. It shows that the predictions of the models are in good agreement with the experimental data.

scholarly journals Effect of Size and Shape on the Vibrational and Thermodynamic Properties of Nanomaterials

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
R. Kumar ◽  
G. Sharma ◽  
M. Kumar
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Size And Shape ◽  
Shape Dependence ◽  
Simple Theoretical Model ◽  
Model Predictions ◽  
Different Shapes ◽  
Debye Frequency ◽  
Good Agreement ◽  
Melting Entropy

A simple theoretical model is developed to study the size and shape dependence of vibrational and thermodynamic properties of nanomaterials. To show the real connection with the nanomaterials we have studied Debye temperature, Debye frequency, melting entropy, and enthalpy in different shapes, namely, spherical, nanowire, and nanofilm of -Fe, Sn, Ag, and In. The results obtained are compared with the experimental data. A good agreement between the model predictions and the experimental data supports the theory developed in the present paper.

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.

SIZE AND TEMPERATURE EFFECT ON THERMAL EXPANSION COEFFICIENT AND LATTICE PARAMETER OF NANOMATERIALS

2013 ◽  
Vol 27 (25) ◽  
pp. 1350180 ◽  
Author(s):  
RAGHUVESH KUMAR ◽  
GEETA SHARMA ◽  
MUNISH KUMAR
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Temperature Dependence ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Size Dependence ◽  
Coefficient Of Thermal Expansion ◽  
Lattice Parameter ◽  
Model Predictions ◽  
Good Agreement

A simple theoretical model is developed to study the effect of size and temperature on the coefficient of thermal expansion and lattice parameter of nanomaterials. We have studied the size dependence of thermal expansion coefficient of Pb , Ag and Zn in different shape viz. spherical, nanowire and nanofilm. A good agreement between theory and available experimental data confirmed the model predictions. We have used these results to study the temperature dependence of lattice parameter for different size and also included the results of bulk materials. The temperature dependence of lattice parameter of Zn nanowire and Ag nanowire are found to present a good agreement with the experimental data. We have also computed the temperature and size dependence of lattice parameter of Se and Pb for different shape viz. spherical, nanowire and nanofilm. The results are discussed in the light of recent research on nanomaterials.

Analysis of the Equilibrium Approximation in Chemical Ablation of Thermal Protective Systems

2012 ◽  
Author(s):  
B. W. Barr ◽  
O. A. Ezekoye
Keyword(s):  
Experimental Data ◽  
Complex Surface ◽  
Damkohler Number ◽  
Damköhler Number ◽  
Graphite Oxidation ◽  
Model Predictions ◽  
Surface Equilibrium ◽  
Carbon Combustion ◽  
New Formulation ◽  
Good Agreement

A quasi-steady-state ablation model is used to investigate the behavior of thermochemically ablating systems in equilibrium and nonequilibrium surface thermochemistry regimes. The model is simplified to allow extraction of relevant nondimensional parameters and comparison with existing experimental data on solid carbon combustion. Good agreement is found between model predictions and experimental data, and the data and model are collapsed in terms of the B number and surface Damkohler number. A new formulation for the surface Damkohler number is proposed, and a relationship between the B number and this Damkohler number is derived for the surface equilibrium and nonequilibrium regimes. The Damkohler formulation is applied to the reentry scenario, and the behavior of the B number in this context is explored. Nondimensional parameters governing behavior in the nonequilibrium regime are determined for graphite oxidation, and the results are extrapolated to more complex surface thermochemistry conditions.

scholarly journals Mathematical Model of VOCs Emission in Three-layer Building Materials

2021 ◽  
Vol 257 ◽  
pp. 03047
Author(s):  
Zhehua Du ◽  
Xin Lin
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Mathematical Model ◽  
Building Materials ◽  
Present Model ◽  
Transfer Resistance ◽  
Model Predictions ◽  
Layer Resistance ◽  
Boundary Layer Resistance ◽  
Good Agreement

A simple mathematical model is proposed to account for emissions of Volatile Organic Compounds (VOCs) from three-layer building materials. The model considers both the diffusion within three layer building materials and the mass transfer resistance through the air boundary layer. A general solution method based on Laplace transform is presented. Compared to other models capable of accounting for emissions of VOCs from multi layer building materials, the present model is fully analytical instead of being numerical. The present model was validated by the experimental data from the specially designed test. The results indicated that there was a good agreement between the model predictions and the experimental data. It can also be seen from calculation that model ignoring the boundary layer resistance cannot fully reflect the real situation.

Falling-Film Solidification Rates for Water inside a Short Vertical Tube

1972 ◽  
Vol 94 (3) ◽  
pp. 305-309 ◽  
Author(s):  
T. E. Mullin ◽  
R. B. Renda
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Temperature Difference ◽  
Film Flow ◽  
Vertical Tube ◽  
Falling Film ◽  
Reasonable Accuracy ◽  
Fusion Temperature ◽  
Ice Field ◽  
Good Agreement

The purpose of this investigation was twofold: (1) to present the results of an experimental investigation of the solidification rates for water at its fusion temperature in falling-film flow inside a short vertical tube and (2) to compare the experimental results to those predicted from the expression developed by London and Seban [1]. The experimental data were in good agreement with those values predicted by their expression when evaluated on a weight-of-ice-formed basis. However, the liquid-solid interface radius rs could be determined with reasonable accuracy only for large values of rs. It was shown that by increasing the temperature difference across the ice field, closer agreement was obtained in both cases. It is believed that erosion of the ice by the liquid falling film is responsible for most of the deviations.

FRACTAL ANALYSIS OF GAS DIFFUSION IN POROUS NANOFIBERS

Fractals ◽  
2015 ◽  
Vol 23 (01) ◽  
pp. 1540011 ◽  
Author(s):  
BOQI XIAO ◽  
JINTU FAN ◽  
ZONGCHI WANG ◽  
XIN CAI ◽  
XIGE ZHAO
Keyword(s):  
Experimental Data ◽  
Fractal Dimension ◽  
Fractal Theory ◽  
Fractal Dimensions ◽  
Fractal Model ◽  
Gas Diffusion ◽  
Physical Mechanisms ◽  
Gas Diffusivity ◽  
Model Predictions ◽  
Good Agreement

In this study, with the consideration of pore size distribution and tortuosity of capillaries, the analytical model for gas diffusivity of porous nanofibers is derived based on fractal theory. The proposed fractal model for the normalized gas diffusivity (De/D0) is found to be a function of the porosity, the area fractal dimensions of pore and the fractal dimension of tortuous capillaries. It is found that the normalized gas diffusivity decreases with increasing of the tortuosity fractal dimension. However, the normalized gas diffusivity is positively correlated with the porosity. The prediction of the proposed fractal model for porous nanofibers with porosity less than 0.75 is highly consistent with the experimental and analytical results found in the literature. The model predictions are compared with the previously reported experimental data, and are in good agreement between the model predictions and experimental data is found. The validity of the present model is thus verified. Every parameter of the proposed formula of calculating the normalized gas diffusivity has clear physical meaning. The proposed fractal model can reveal the physical mechanisms of gas diffusion in porous nanofibers.

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