Numerical Modelling of Large Length-to-Diameter Ratio Vertical Concentric-Tube Ground-Coupled Heat Exchangers

2017 ◽  
Author(s):  
L. W. Jin ◽  
G. S. Jia ◽  
L. Y. Zhang ◽  
X. H. Yang ◽  
Y F Yap ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Heat Exchangers ◽  
Diameter Ratio ◽  
Large Length ◽  
Length To Diameter Ratio

Optimal Parameters Analysis of Dynamical Vibration Absorption Lathe Tool with Large Length to Diameter Ratio

2011 ◽  
Vol 121-126 ◽  
pp. 2146-2150
Author(s):  
Bai Qin ◽  
Bo Zhang ◽  
Xiao Dong Yu ◽  
Yan Qin Zhang ◽  
Gui Hua Han ◽  
...  
Keyword(s):  
Frequency Response ◽  
Diameter Ratio ◽  
Flexible Body ◽  
Equivalent Viscous Damping ◽  
Vibration Absorption ◽  
Large Length ◽  
Relationship Of ◽  
System Frequency ◽  
Lathe Tool ◽  
Length To Diameter Ratio

The multi flexible body dynamical simulation model of dynamical vibration absorption lathe tool with large length to diameter ratio is built up according to the actual experiment lathe tool by using the software ADAMS and ANSYS. The experiment data which are consistent with the simulation result verify the correctness of the multi flexible body dynamical model. Aiming at reducing the peak value of system frequency response, the dynamical vibration absorption system is optimized. The optimized frequency curve shows that the system frequency response is improved obviously. On this basis the influence of the mass of heavy turning body on the vibration system is discussed. Also, the relationship of the mass of heavy turning body and the optimal system parameters including equivalent stiffness coefficient and equivalent viscous damping coefficient is studied. This offers the design considerations about the structure of the dynamical vibration absorption lathe tool with large length to diameter ratio.

Research on Simulation and Design of Dynamical Vibration Absorption Lathe Tool with Large Length to Diameter Ratio

2013 ◽  
Vol 274 ◽  
pp. 99-102
Author(s):  
Bai Qin ◽  
Bo Zhang ◽  
Quan Fu Wang ◽  
Ya Juan Ji ◽  
Yan Jiang Zhao ◽  
...  
Keyword(s):  
Simulation Analysis ◽  
Diameter Ratio ◽  
Flexible Body ◽  
Vibration Absorption ◽  
Ansys Simulation ◽  
Damping Characteristics ◽  
Large Length ◽  
Relationship Of ◽  
Lathe Tool ◽  
Length To Diameter Ratio

The dynamic simulation analysis method is adopted to investigate the dynamic damping characteristics of lathe tool with large length to diameter (L/D) ratio. The multi flexible body dynamical simulation model of dynamical damping lathe tool with large length to diameter ratio is built up according to the actual experiment lathe by using the software ADAMS and ANSYS. Simulation analysis of the multi flexible body dynamical model which has been optimized shows that the system damping performance is improved greatly. On this basis the relationship of rubber bush, mass body and vibration absorption cavity is discussed. And the result of the discussion indicates that the shape of rubber bush should be confirmed by repeatedly simulating the model.

Numerical modelling of the effects of vessel length-to-diameter ratio (L/D) on pressure piling

2021 ◽  
Vol 70 ◽  
pp. 104398
Author(s):  
Damilare Ogungbemide ◽  
Martin P. Clouthier ◽  
Chris Cloney ◽  
Robert G. Zalosh ◽  
Robert C. Ripley ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Diameter Ratio ◽  
Vessel Length ◽  
Length To Diameter Ratio

Theoretical and experimental analysis of a water-lubricated rubber journal bearing with a large aspect ratio

2020 ◽  
Vol 72 (6) ◽  
pp. 797-803
Author(s):  
Zhiming Zhao ◽  
Rui Zhang
Keyword(s):  
Aspect Ratio ◽  
Liquid Film ◽  
Journal Bearings ◽  
Diameter Ratio ◽  
Hydrodynamic Characteristics ◽  
Large Aspect Ratio ◽  
Content Type ◽  
Large Length ◽  
Theoretical Results ◽  
Length To Diameter Ratio

Purpose The hydrodynamic characteristics of liquid film for bearings, especially water-lubricated bearings with a large length-to-diameter ratio, affect the dynamics behavior of rotor bearing systems. The purpose of this study is to carry out theoretical analysis and experiments to determine the hydrodynamic characteristics of water-lubricated journal bearings. Design/methodology/approach The finite difference method is adopted for the simulation of the characteristics of water-lubricated bearings. The comparison results between water-lubricated bearings with and without grooves, as well as with and without the consideration of the effects of rubber deformation, are presented. The test bearings, test bench, and monitoring system, especially the force exciter for the bearing experiment, are presented. Dynamic coefficient identification verification experiments were performed in different working situations. The obtained results include the calibration of magnetic force, two kinds of excitation, vibration data of the rotor system and dynamic coefficients. Findings The theoretical results demonstrate that the hydrodynamic effect was obvious when the speed was increased and that the water film had improved capability at a working speed of 1800 rpm. The identification results reveal the lubrication situation of the test bearing under low-speed and high-load conditions. Moreover, it was found that the liquid film was not continuous at low speeds. Originality/value The theoretical results can lead to the enhancement of the design level of water-lubricated rubber journal bearings with a large aspect ratio. The experimental results can lead to the improvement of the dynamic behavior design of rotor systems supported using water-lubricated bearings with a large length-to-diameter ratio.

Passage of a Turbulent Stream Through Honeycomb of Large Length-to-Diameter Ratio

1964 ◽  
Vol 86 (2) ◽  
pp. 218-220 ◽  
Author(s):  
J. L. Lumley
Keyword(s):  
Diameter Ratio ◽  
Cell Length ◽  
Turbulence Level ◽  
Fully Developed Flow ◽  
Mechanical Analogy ◽  
Design Charts ◽  
Large Length ◽  
Length To Diameter Ratio

An analysis is performed, similar to the classical one for screens, of the effect of a honeycomb on a turbulent stream, when the cell length is large enough to permit the flow to become fully developed. The results indicate that a honeycomb should reduce the turbulence level of a stream passing through it more effectively than a screen, due to two effects: (a) The annihilation of the transverse fluctuation, dependent on the assumption of fully developed flow; (b) the effect of the mass of fluid in each cell, which must be accelerated to permit the passage of a fluctuation. The latter suggests that the honeycomb may be viewed as an inductive filter, if the screen is regarded as the fluid mechanical analogy of a resistive one. A small number of measurements in water are presented which lend quantitative support to the argument. Finally, design charts are presented, which permit calculation of the reduction to be expected from the placing of a given honeycomb in a given flow.

A high-performance magnetic shield with large length-to-diameter ratio

2012 ◽  
Vol 83 (6) ◽  
pp. 065108 ◽  
Author(s):  
Susannah Dickerson ◽  
Jason M. Hogan ◽  
David M. S. Johnson ◽  
Tim Kovachy ◽  
Alex Sugarbaker ◽  
...  
Keyword(s):  
High Performance ◽  
Diameter Ratio ◽  
Magnetic Shield ◽  
Large Length ◽  
Length To Diameter Ratio

scholarly journals EXPERIMENTAL RESEARCH ON AEROELASTICITY OF A LARGE LENGTH TO DIAMETER RATIO PROJECTILE

2012 ◽  
Vol 19 ◽  
pp. 270-275
Author(s):  
WENJUN YI ◽  
DONGYANG SUN ◽  
JUNJIE TAN ◽  
DANDAN YUAN
Keyword(s):  
Aerodynamic Force ◽  
Diameter Ratio ◽  
Free Flight ◽  
Flight Stability ◽  
Rigid Projectile ◽  
Aerodynamic Performances ◽  
Large Length ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Length To Diameter Ratio

In order to investigate the aeroelastic influences on the aerodynamic performance and flight stability of a large length to diameter ratio projectile, free-flight experiments on both the flexible and rigid projectile model are performed in our ballistic range. Many groups of shadowgraphs for these two kinds of projectiles during flight tests were taken and one of those typical results is shown. The projectile flight velocity, angle of attack and precession are obtained after the data procession. Moreover, the aerodynamic force and moment coefficients of two kinds of projectiles are presented, their aerodynamic performances and flight stability are compared and analyzed. Our results show that the flexible projectile has larger drag coefficient than the rigid. After the deformation, its lift to drag ratio decreases and its rotation moment increases obviously. The elastic deformation of the flexible projectile has remarkable influence on its flight stability which can induce the flight instability.

Pressure Attenuation in Long Rarefaction Wave Tubes

1969 ◽  
Vol 91 (2) ◽  
pp. 497-500
Author(s):  
M. J. Levy ◽  
H. Gerecke ◽  
J. H. Potter
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Rarefaction Wave ◽  
Initial Pressure ◽  
Diameter Ratio ◽  
Rarefaction Waves ◽  
Gas Dynamic ◽  
Large Length ◽  
Length To Diameter Ratio

This paper reports upon an experimental investigation of gas dynamic rarefaction waves in rarefaction wave tubes to determine effects of large length to diameter ratios. A fitted equation is presented from which reasonable predictions can be made on the pressure deviation between a real and an ideal rarefaction wave. Transient boundary-layer effects cause an attenuation of the pressure which becomes more pronounced as the length to diameter ratio is increased. At a length to diameter ratio of 895, the pressure damping was essentially complete in one cycle for initial pressure ratios in excess of 1.6.

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