Aviation Fuel Gauging Sensor Utilizing Multiple Diaphragm Sensors Incorporating Polymer Optical Fiber Bragg Gratings

Abstract

A high performance fuel gauging sensor is described that uses five diaphragm-based pressure sensors, which are monitored using a linear array of polymer optical fiber Bragg gratings. The sensors were initially characterized using water, revealing a sensitivity of 98 pm/cm for four of the sensors and 86 pm/cm for the fifth. The discrepancy in the sensitivity of the fifth sensor has been explained as being a result of the annealing of the other four sensors. Initial testing in JET A-1 aviation fuel revealed the unsuitability of silicone rubber diaphragms for prolonged usage in fuel. A second set of sensors manufactured with a polyurethane based diaphragm showed no measurable deterioration over a 3 month period immersed in fuel. These sensors exhibited a sensitivity of 39 pm/cm, which is less than the silicone rubber devices due to the stiffer nature of the polyurethane material used.

Phase-Shifted Bragg Grating Inscription in PMMA Microstructured POF Using 248-nm UV Radiation

“…In recent years, the polymer optical fibe Bragg gratings (POFBGs) fabrication technology has been intensively established using uniform FBGs [16]- [19], tilted FBGs [20], chirped FBGs [21], and FBGbased Fabry-Perot interferometers [22]. Specifi material properties, such as low Young's modulus (about 3 GPa compared to 72 GPa for silica), a very large breaking strain, as well as biological compatibility, opens a variety of new applications unattainable for silica fibers In the published literature, one can fin studies reporting on applications of single FBGs in POFs as sensors of strain [23], acoustic waves [24], temperature [23], [25], humidity [25], accelerometer [26] or liquid level [27], [28]. In the last years, there has been an increase in the research of POF technology for biomedical applications [29]- [34].…”

Fuel level sensor based on polymer optical fiber Bragg gratings for aircraft applications

“…This material is based on a mixture of two liquids -MF633 resin and DK780 catalyst -in a ratio of 100:100 by volume and curing at room temperature in 8 hours (23°C, 40% relative humidity). This material shows less flexibility than the previous one we used [24,26], however it is resistant to the fuel. A diaphragm with the same dimensions as the previous manufactured diaphragms was placed in JET A-1 for more than 3 months with no measurable change in size.…”

“…Despite initially promising results with Jet A-1, the SILASTIC diaphragms were found to be unsuitable for long-term measurements as reported in [24]. After a few hours exposed to the fuel, the diaphragms were observed to swell to almost twice their original size as shown in Figure 3.…”

“…On the other hand, using silicone rubber diaphragms, this mPOFBG array sensor system exhibits a factor of 4 improvement in sensitivity (~98 pm/cm) when compared with the best approach based on silica optical fiber published in the literature. However, despite the promising initial performance, longer term tests revealed the diaphragm material to be unsuitable for prolonged use [24]. In addition, tests in JET A-1 fuel to investigate the time-dependent variation of both the amplitude and resonance wavelength of mPOFBG array sensors embedded in diaphragms were reported.…”

“…Recently, we reported the study of these sensors using water, revealing an average sensitivity of 98.2 ± 0.4 pm/cm water depth. Furthermore, initial testing in JET A-1 aviation fuel revealed the unsuitability of the silicone rubber diaphragm for prolonged usage in fuel [24]. A second set of sensors manufactured with a polyurethane based diaphragm showed no measurable deterioration over a 3-month period immersed in fuel.…”