Development of Measurement Method for Temperature and Velocity Field with Optical Fiber Sensor

Abstract

We have developed a new method for measuring temperature and velocity at a high spatial resolution (minimum 2.56 mm pitch along an optical fiber). The developed method uses the same principle as a hot wire anemometer, where the velocity perpendicular to an optical fiber is estimated as a function of the cooling curve of a gold-coated layer on the optical fiber Joule-heated intermittently. The developed optical fiber sensor demonstrated the ability to acquire a transient velocity profile in airflow experiments with high repeatability and accuracy. This paper describes optical fiber-based velocity measurement in the velocity range of approximately 0–7 m/s with an error of approximately 10% compared to a hot wire anemometer and a new method for simultaneous temperature and velocity measurements. Applicability to velocity distribution measurements and seconds transient velocity changes are also described.

Improvement of Temperature Measurement Accuracy of Hot Airflow Using Ultrafine Thermo-Sensitive Fluorescent Wires of Lumisis Phosphor

“…However, the center wavelengths of the RGB elements of a color camera are approximately 100 nm apart, which limits the ability to measure slight color changes with high precision. In a previous study, we constructed a two-wavelength spectral optical system (center wavelengths: 570 and 610 nm), to improve the accuracy of the temperature measurement in the wavelength range of yellow to red coloration [ 19 ]. Pyrromethene 597 phosphor showed a slight temperature dependence on the fluorescence center wavelength [ 19 ], allowing for the temperature distribution of the optical fluorescent material in a two-wavelength spectrometer to be measured at two wavelengths.…”

“…In a previous study, we constructed a two-wavelength spectral optical system (center wavelengths: 570 and 610 nm), to improve the accuracy of the temperature measurement in the wavelength range of yellow to red coloration [ 19 ]. Pyrromethene 597 phosphor showed a slight temperature dependence on the fluorescence center wavelength [ 19 ], allowing for the temperature distribution of the optical fluorescent material in a two-wavelength spectrometer to be measured at two wavelengths. The Lumisis phosphors employed in this study are a combination of green and red phosphors, allowing for two-wavelength measurements using the red and green imaging elements of a color camera without modification.…”

“…Therefore, we investigated and developed a method for LIF measurements based on the wavelength distribution of a single type of phosphor and used it to measure the temperature distribution of a transmission oil [ 19 ]. Our investigation took advantage of the fact that the peak of the fluorescence wavelength distribution of pyrromethene 597, a type of inorganic phosphor, is temperature-dependent.…”

Sequential Dual Coating with Thermosensitive Polymers for Advanced Fiber Optic Temperature Sensors

“…Optical-fiber-based sensors are becoming increasingly mature and in greater demand in the fields of energy, biotechnology, biomedicine, superconducting magnets, automotive technology, aerospace, healthcare, and civil engineering [ 1 , 2 , 3 , 4 , 5 , 6 ]. These sensors have been extensively researched due to their advantages, such as passive operation, ease of fabrication, compact size, resistance to corrosion, remote sensing ability, capacity for distant sensing, and resistance to electromagnetic interference [ 7 , 8 , 9 , 10 , 11 ].…”

A Thermal Anemometry Method for Studying the Unsteady Gas Dynamics of Pipe Flows: Development, Modernisation, and Application

“…Optical fibre makes it possible to significantly increase the sensitivity of measuring systems, capturing even the slightest fluctuations in gas flow. M. Sekine and M. Furuya compared the technical specifications of the traditional method based on a hot-wire anemometer and HWAs with a fibre-optic sensor [ 14 ]. The comparison was made for airflow velocities up to 7 m/s.…”