Void fraction measurement and simultaneous measurement of velocity and diameter of bubbles in a gas-liquid two-phase flow
The BubbleMaster is an instrument to measure gas-liquid two-phase flows with optical fiber sensors. It measures not only time-averaged void fraction, but also detects individual bubble size and velocity using reflected light intensity technology that changes when a bubble penetrates through the tip of the wedge-shaped optical fiber.
Three types of sensor tip, called S-TOP, T-TOP and F-TOP, made of quartz are available. The intrusive approach of the BubbleMaster enables to measure even at a higher void fraction of over 1 %, which cannot be realized by a non-intrusive optical method.
The BubbleMaster software acquires samples from individual bubbles, which signal amplitude can be monitored on the software display. As analysis results, histogram of bubble velocity and diameter, void faction, averages and standard deviation can be obtained with the T-TOP and F-TOP sensor.
| Measurement Specifications | |
| Method | Photoelectric detection |
|---|---|
| Number of Channels | 4 Channels |
| Sensors | |
| Shape | Wedge-shaped |
| Measurable Bubble Size | > 1.0 mm |
| Applicable Velocity | < 5 m/s |
| Type of Sensors | S-TOP, T-TOP and F-TOP |
| Software | |
| Sampling System | Burst signal sampling |
| Sampling Mode | Trigger mode, Continuous sampling mode |
| Real Time Monitor | Photoelectric conversion output signal |
| Data Acquisition | Max. 100,000 (number of bubbles) |
| Analysis Data (S-TOP sensor) | Bubble signal waveform, Void fraction |
| Analysis Data (T-TOP / F-TOP sensor) |
Bubble signal waveform, Void fraction, Bubble velocity, Bubble diameter, Average value, Standard deviation |
| Data Table | Bubble velocity, Bubble size |
| Histogram Chart | Bubble velocity, Bubble size |
| Supported Operating System | Windows 10 (64bit), Japanese / English | Power Supply |
| Voltage | AC 90V ~ 240 V |
| Frequency | 50 Hz / 60 Hz |
| Appearance (main unit) | |
| Dimension | 255 mm x 313 mm x 153 mm |
| Weight | approx. 4.5 kg |
Specifications subject to change without notice.
< Quick Reference of Sensor Type and Measurable Items >| Output Data | S-TOP | T-TOP | F-TOP |
|---|---|---|---|
| Void Fraction | 〇 | 〇 | 〇 |
| Signal Waveform | 〇 | 〇 | 〇 |
| Bubble Velocity | X | 〇 | 〇 |
| Bubble Diameter | X | 〇 | 〇 |
| Bubble Entry Angle | X | X | 〇 |
| Average Value | X | 〇 | 〇 |
| Standard Deviation | X | 〇 | 〇 |
The BubbleMaster utilizes the change of reflected laser light intensity caused by the difference of refractive index between two phases, liquid and gas. The BubbleMaster can determine whether it is in a gas-phase or liquid-phase at the measurement point.
S-TOP Sensor Principle
The signal change is detected when a bubble contacts and penetrates the sensor, by which transit time of the bubble is to be obtained and time-averaged void fraction is to be calculated.
T-TOP Sensor Principle
Velocity is calculated based on the temporal differences of a bubble passing through two sensors.
F-TOP Sensor Principle
The F-TOP Sensor delivers a highly accurate measurement by having four integrated wedge-shaped optical fibers in one. By the phase difference and gradient of each optical fiber sensor detection signal, the bubble entry angle is calculated and an error of bubble size by the penetration angle can be reduced.
■Block Diagram
This product was developed with Regional Innovation Creation R&D Programs for FY 2008 supported by Kanto Bureau of Economy, Trade and Industry.
Project leader: Prof. Takayuki Saito, Shizuoka University
BubbleMaster Software as Reference
Bubbles passing through the BubbleMaster probe
