Influence of Electric Fields on Flow of Liquid Crystal Mixture in a Circular Tube With Electrode Surface

2003 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
Tsuyoshi Mitani
Keyword(s):  
Liquid Crystal ◽  
Pressure Drop ◽  
Electric Fields ◽  
Pulse Width Modulation ◽  
Circular Tube ◽  
Pulse Frequency ◽  
Open Loop ◽  
Test Facility ◽  
Pulse Frequency Modulation ◽  
Crystal Mixture

Liquid crystal is one of functional fluids to control an apparent viscosity using an electric field intensity. It is also called ER (Electro-rheological) fluids. In the present experiment a liquid crystal mixture made of some kinds of the nematic liquid crystal is used. The responses of the pressure drop are examined when the liquid crystal mixture flows in a circular tube with the electrode walls on some parts of the inner surface of the tube for the constant flow rates. The four pair of the electrode is used and the voltages are added in the peripheral direction. When the voltages are applied on the liquid crystal mixture and removed, the pressure responses of the inlet of the circular tube are measured with the pressure transducer. On the other hand, the pulse-wave voltages are added to the electrodes to control the pressure drop using the pulse width modulation or the pulse frequency modulation. The diameter of the circular tube is 1.0mm. The isotropic-nematic transition is 90.0°C and smectic-nematic transition is −44.0°C for the liquid crystal mixture. The open-loop test facility with the liquid crystal mixture is set in a pyrostat to keep the temperature constant.

Influence of Electric Fields on Pressure Drop of Liquid Crystal Mixture

2002 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
Tsuyoshi Mitani
Keyword(s):  
Liquid Crystal ◽  
Pressure Drop ◽  
Electric Fields ◽  
Parallel Plate ◽  
Time History ◽  
Open Loop ◽  
Test Facility ◽  
Pulse Frequency Modulation ◽  
Flow Rates ◽  
Crystal Mixture

Liquid crystal is one of homogeneous ER (Electrorheological) fluids in some range of temperature. In the present experiment a liquid crystal mixture is used. The responses of the pressure drop are examined when the liquid crystal mixture flows between two parallel-plate electrodes for the constant flow rates. When the voltages are applied on the liquid crystal mixture and removed, the pressure responses of the inlet electrodes are measured with the pressure transducer. At same time, the liquid crystal mixture between the transparent electrodes made of glass is visualized with the video camera investigate the time history of the director of the liquid crystal mixture. The AC voltages are also used to investigate dependence of the liquid crystal mixture on the frequency the voltages. Outlet of the flow channel with two parallel-plate electrodes is atmosphere. Relation between the flow visualization results and the changes of pressure drop investigated especially for transient period. On the other hand, the pulse-wave voltages are added to the electrodes to control the pressure drop using the pulse width modulation or the pulse frequency modulation. In the present study the flow rates change from 0.001cc/sec (velocity is lmm/sec) to 0.003cc/sec and the electric field intensity is from 0.2kV/mm to lkV/mm. The gap of the electrodes is 0.2mm.The isotropic-nematic transition is 90.0°C and smectic-nematic transition is −44.0°C for the liquid crystal mixture. The open-loop test facility the liquid crystal is set in a pyrostat to keep the temperature constant.

FLOW CHARACTERISTICS OF A LIQUID CRYSTAL MIXTURE IN A CIRCULAR PIPE ELECTRODE

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1346-1352
Author(s):  
TETSUHIRO TSUKIJI ◽  
EITARO KOYABU
Keyword(s):  
Liquid Crystal ◽  
Pressure Drop ◽  
Electric Fields ◽  
Flow Rate ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Flow Direction ◽  
Flow Analysis ◽  
Circular Pipe ◽  
Crystal Mixture

A circular pipe electrode was developed to control the pressure and the flow rate of the ER(Electro-rheological) fluids by one of the authors. The shape of the electrode is a circular pipe and some parts of the inner surface of the pipe are the electrode. The diameter of the tube is 1mm and the four pairs of the electrode are used. In the present study a liquid crystal mixture is selected for a homogeneous ER fluid and the pressure drop of the circular pipe electrode is measured for the constant flow rates under application of the voltages. The voltages are added in the peripheral direction. The director which is the average direction of the molecular of the liquid crystal is perpendicular to the flow direction. On the other hands, numerical analysis of the electric fields and the flow in the circular pipe electrode is conducted and the relations between the flow rate and the pressure are obtained for various electric field intensities, which almost agree with experimental results. The emphasized point of the present flow analysis is assuming that the viscosity of a liquid crystal mixture distributes in the flow field. Furthermore the pulse-wave voltages are added to the electrodes to control the pressure drop using the pulse width modulation. It is found that the pressure can be controlled using the pulse width modulation in the some range of the parameters.

ER EFFECT OF LIQUID CRYSTAL FLOWING BETWEEN TWO PARALLEL-PLATE ELECTRODES

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2569-2575 ◽  
Author(s):  
TETSUHIRO TSUKIJI ◽  
SHINSUKE TANABE
Keyword(s):  
Liquid Crystal ◽  
Pressure Drop ◽  
Parallel Plate ◽  
High Speed ◽  
Time History ◽  
Video Camera ◽  
Open Loop ◽  
Test Facility ◽  
Flow Rates ◽  
Temperature Constant

Liquid crystal is one of homogeneous ER(Electro-rheological) fluids in some range of temperature. Transient responses of pressure drop are examined when liquid crystal flows between two parallel-plate electrodes for constant flow rates. When voltages are applied on the liquid crystal and removed, the pressure responses of the inlet of electrodes are measured with the pressure transducer. At the same time, liquid crystal between the transparent electrodes made of glass is visualized with the high-speed video camera to investigate the time history of the director of the liquid crystal. Outlet of the flow channel with two parallel-plate electrodes is atmosphere. Relation between the flow visualization results and the changes of pressure drop is investigated especially for transient period. In the present experiment the flow rates change from 0.001 cc/sec(velocity is 1 mm/sec) to 0.003 cc/sec and the electric field intensity is from 0.2 kV/mm to 1 kV/mm. The gap of the electrodes is 0.2 mm. The isotropic-nematic transition is 35.5°C and smectic-nematic transition is 23.1°C. The open-loop test facility with the liquid crystal is set in a pyrostat to keep the temperature constant.

Pressure Drop of Liquid Crystal Flowing Between Two Parallel-Plate Electrodes

2001 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
Shinsuke Tanabe
Keyword(s):  
Liquid Crystal ◽  
Pressure Drop ◽  
Parallel Plate ◽  
High Speed ◽  
Time History ◽  
Video Camera ◽  
Open Loop ◽  
Test Facility ◽  
Flow Rates ◽  
Temperature Constant

Abstract Liquid crystal is one of homogeneous ER (Electrorheological) fluids in some range of temperature. Transient responses of pressure drop are examined when liquid crystal flows between two parallel-plate electrodes for constant flow rates. When voltages are applied on the liquid crystal and removed, the pressure responses of the inlet of electrodes are measured with the pressure transducer. At the same time, liquid crystal between the transparent electrodes made of glass is visualized with the high-speed video camera to investigate the time history of the director of the liquid crystal. Outlet of the flow channel with two parallel-plate electrodes is atmosphere. Relation between the flow visualization results and changes of pressure drop is investigated especially for transient period. In the present experiment the flow rates change from 0.001cc/sec (velocity is 1mm/sec) to 0.003cc/sec and the electric field intensity is from 0.2kV/mm to 1kV/mm. The gap of the electrodes is 0.2mm. The isotropic-nematic transition is 35.5°C and smectic-nematic transition is 23.1°C. The open-loop test facility with the liquid crystal is set in a pyrostat to keep the temperature constant.

scholarly journals Influence of Electric Fields on the Flow of a Liquid Crystal Mixture in Circular-Pipe Electrodes

2005 ◽  
Vol 48 (3) ◽  
pp. 517-523 ◽  
Author(s):  
Tetsuhiro TSUKIJI ◽  
Eitaro KOYABU ◽  
Tomohiro TSUJI ◽  
Shigeomi CHONO
Keyword(s):  
Liquid Crystal ◽  
Electric Fields ◽  
Circular Pipe ◽  
Crystal Mixture

PWM/PFM Dual-Mode Synchronous Boost DC-DC Regulator

2013 ◽  
Vol 380-384 ◽  
pp. 3209-3212
Author(s):  
Wen Yuan Li ◽  
Jun Zhang
Keyword(s):  
Pulse Width Modulation ◽  
Pulse Frequency ◽  
Dual Mode ◽  
Pulse Frequency Modulation ◽  
Good Efficiency ◽  
Signal Regeneration ◽  
Soft Start ◽  
Start Up ◽  
Simulation Results ◽  
Surge Current

a novel peak current PWM/PFM dual-mode boost dc-dc regulator applying for neural signal regeneration is proposed in this paper. The converter can adaptively switch between pulse-width modulation (PWM) and pulse-frequency modulation (PFM) both with relatively high conversion efficiency. Soft-start circuit is designed to eliminate the surge current at the start up stage of the regulator, other protection modules are also contained. The paper analyzes the model and stability of the system. The operation frequency of the regulator is 1MHz. The simulation results show the efficiency of the system is relatively high in PWM mode, up to 95%, in PFM mode it also has good efficiency.

Influence of electric fields in the flow of a liquid crystal mixture in circular pipe electrodes

2004 ◽  
Vol 2004 (0) ◽  
pp. 69
Author(s):  
Tetsuhiro TSUKIJI ◽  
Eitarou KOYABU ◽  
Tomohiro TSUJI ◽  
Shigeomi CHONO
Keyword(s):  
Liquid Crystal ◽  
Electric Fields ◽  
Circular Pipe ◽  
Crystal Mixture
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