Simultaneous measurement of film thickness and wave velocity in liquid-film flow with an optical fiber probe, micro-fabricated by a femtosecond pulse laser

2021 ◽  
pp. 116704
Author(s):  
Hajime Furuichi ◽  
Yuki Mizushima
Keyword(s):  
Optical Fiber ◽  
Film Thickness ◽  
Liquid Film ◽  
Wave Velocity ◽  
Pulse Laser ◽  
Simultaneous Measurement ◽  
Femtosecond Pulse ◽  
Film Flow ◽  
Optical Fiber Probe ◽  
Liquid Film Flow

Bubbles and Droplets Measurement via Optical Fiber Probe Processed by Femtosecond Pulse Laser

2008 ◽  
Author(s):  
Takayuki Saito ◽  
Yusuke Ozawa ◽  
Keisuke Matsuda ◽  
Shin-Ichiro Aoshima
Keyword(s):  
Light Intensity ◽  
Optical Fiber ◽  
Pulse Laser ◽  
Simultaneous Measurement ◽  
Femtosecond Pulse ◽  
Detection Characteristic ◽  
Fiber Probe ◽  
Femtosecond Pulse Laser ◽  
Optical Fiber Probe ◽  
Reflected Light

An optical fiber has interesting and useful characteristics, which are able to be applied to scientific measurement. Its phase detection characteristic based on refraction difference between two phases is applied to bubbles/droplets measurement. Recently, demands for measurement of tiny bubbles/droplets increase in research fields of steam injectors, sprays, automotive engines, fine chemical reactors, and so on. Meanwhile, laser science and engineering, particularly femtosecond pulse laser, has made remarkable advances lately. Their unique properties of the interaction between the femtosecond pulses and materials can be utilized for microfabrication. The optical fiber probe methods have been repeatedly improved in order to measure bubbles/droplets efficiently and reliably in gas-liquid two-phase flows. However, one has been taking it for granted that simultaneous measurement of their diameters and velocities needs at least two optical fiber probes. To break through this situation, we newly developed a Single-Tip Optical Fiber Probe (F-STOP) microfabricated by femtosecond pulse laser (fs-pulses) which realizes simultaneous measurement of diameters and velocities of tiny bubbles/droplets. In the F-STOP measurement, the following properties are used to realize the simultaneous measurement of diameters and velocities of bubbles/droplets: the relation between the reflected-light intensity at the wedge-shaped probe tip and the tip-surface area covered with a phase; reflected-light intensity at the groove microfabricated by fs-pulses. The first aim of the present study is to provide data for evaluation of the influences of surface tension and wettability on the bubble measurement in order to develop precise and reliable F-STOP method. The second aim is to describe the process to make F-STOP via fs-pulses. The third aim is demonstration of the newly developed probe in real measurement of bubbles/droplets. On the basis of these, the performance of the new probe is discussed.

345 Developing a measurement technique of micro bubbles and droplets using an Optical Fiber Probe processed by Femtosecond Pulse Laser

2008 ◽  
Vol 2008.8 (0) ◽  
pp. 89-90
Author(s):  
Yusuke OZAWA ◽  
Keisuke MATSUDA ◽  
Shingo OISHI ◽  
Shin-ichiro AOSHIMA ◽  
Toshiyuki SANADA ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Pulse Laser ◽  
Measurement Technique ◽  
Femtosecond Pulse ◽  
Fiber Probe ◽  
Femtosecond Pulse Laser ◽  
Optical Fiber Probe

Studies on Gas-Phase Turbulence Modification in Vertical Upward Annular Flow

2003 ◽  
Author(s):  
Kenji Yoshida ◽  
Hidenobu Tanaka ◽  
Keizo Matsuura ◽  
Isao Kataoka
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Gas Phase ◽  
Annular Flow ◽  
Film Flow ◽  
Velocity Profiles ◽  
Fluctuation Velocity ◽  
Turbulence Modification ◽  
Liquid Film Flow ◽  
Wavy Interface

Experimental and numerical studies were made to investigate the effects of wavy interface on the liquid film to gas-phase turbulence modification of air-water annular flow in a vertically arranged round tube. By using the constant temperature hotwire anemometer, time-averaged axial velocity profiles, turbulence fluctuation profiles, energy spectrum and auto-correlation coefficient for fluctuation velocity component of gas-phase axial velocity were precisely measured. The liquid film thickness was also measured by using point-electrode resistivity probe to make clear the time-averaged liquid film thickness and wave height moving on the liquid film. Direct observations using high speed video camera were also added to make clear the dynamic behavior and propergating velocity of ripple or disturbance waves on liquid film flow. Numerical simulations for gas-phase turbulence in annular flow considering the effect of wavy interface of liquid film flow were also carried out. Liquid film flow was modeled to be the wall surface roughness of interfacial wave height moving with the interfacial velocity. The roughness and moving velocity of the modeled liquid film for computational condition were provided by the present experimental results. Time-averaged velocity profiles and fluctuation velocity profiles were calculated with standard k-ε model. Numerical results were generally consistent with the experimental results obtained in the present study.

Developing Laminar Gravity-Driven Thin Liquid Film Flow Down an Inclined Plane

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
H. Lan ◽  
J. L. Wegener ◽  
B. F. Armaly ◽  
J. A. Drallmeier
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
Film Flow ◽  
Thin Liquid Film ◽  
Inclined Plane ◽  
Liquid Film Flow ◽  
Gravity Driven ◽  
Surface Inclination

Three-dimensional (3D)—steady-developing-laminar-isothermal—and gravity-driven thin liquid film flow adjacent to an inclined plane is examined and the effects of film flow rate, surface tension, and surface inclination angle on the film thickness and film width are presented. The film flow was numerically simulated using the volume of fluid model and experimental verification was conducted by measuring film thickness and width using a laser focus displacement instrument. The steady film flow that is considered in this study does not have a leading contact line, however, it has two steady side contact lines with the substrate surface at the outer edge of its width. Results reveal that the film width decreases and the average film thickness increases as the film flows down the inclined plane. The film thickness and width decrease but its streamwise velocity increases as surface inclination angle (as measured from the horizontal plane) increases. A higher film flow rate is associated with a higher film thickness, a higher film width, and a higher average film velocity. Films with higher surface tension are associated with a smaller width and a higher average thickness. A ripple develops near the side contact line, i.e., the spanwise distribution of the film thickness exhibits peaks at the outer edges of the film width and the height of this ripple increases as the surface tension or the film flow rate increases. The width of the film decreases at a faster rate along the streamwise direction if liquid film has higher surface tension. Measurements of the film thickness and the film width compare favorably with the numerically simulated results.

Hydrodynamic Behavior of Swirling Liquid Film Flow on Rotating Disc

2003 ◽  
Author(s):  
Kenji Yoshida ◽  
Tomoya Adachi ◽  
Isao Kataoka ◽  
Hiroyuki Horiki ◽  
Akira Yoneya ◽  
...  
Keyword(s):  
Film Thickness ◽  
Turbulent Flow ◽  
Liquid Film ◽  
Flow Rate ◽  
Film Flow ◽  
Three Dimensional ◽  
Hydrodynamic Behavior ◽  
Rotating Disc ◽  
Rotating Speed ◽  
Liquid Film Flow

Experimental and analytical studies have been carried out on the hydrodynamic behavior of swirling liquid film flow on a rotating disc. Film flow formation and swirling waves on the liquid film were analyzed through observation using high speed video. Liquid film thickness was measured using the Laser refraction method and compared with prediction. The rotating disc is 200 mm in diameter and was made of Silicon (Silicon wafer in industrial use). The rotating speed is up to 100 rad/sec (2000 rotations per min.) Water is supplied to the center of the disc at a flow rate of 8.3 × 10−6 m3/s (500 cc/min). The film flow is divided into three regimes depending upon rotating speed. For the lower rotating speed (up to 10 rad/sec), formation of liquid film flow is incomplete and some part of the peripheral region of the disc is not completely covered by liquid film. For the intermediate rotating speed (15–25 rad/sec), laminar film flow covered the whole disc. Furthermore, there are swirling waves on the liquid film. This wave is considered to be a continuity wave arising at the center portion of disc due to the water flow rate variation form the nozzle. Wave propagation speed and behavior of these swirling waves were well explained by the theory of continuity wave. For the high rotating speed (more than 30 rad/sec), the liquid film flow changed its flow regime from laminar flow to turbulent flow. The estimated film Reynolds number at transition is about 1200 which is consistent with turbulent flow transition for pipe flow and film flow on non-rotating surface. Three dimensional turbulent waves were observed on this turbulent liquid film. The behavior of such three dimensional turbulent waves were quite random in time and space. Measured film thicknesses ranged from 50 to 300 micron. Film thickness and its fluctuation decreased as the rotation speed of disc increased and distance from disc center increased. The analysis was made on the film thickness based on the force balance between shear stress and centrifugal force acting on the film. The predicted film thickness agreed well with the measured value.

Sign in / Sign up

Export Citation Format

Share Document