This paper describes the first successful fiber optic oxygen detection sensor systems developed for the Boeing Delta IV Launch Vehicle harsh environment of engine section. It illustrates a novel multi-point fiber optic microsensor (optrode) based on dynamic luminescence quenching that was developed for measuring oxygen leak detection for the space applications. The sensor optrodes employ the quenching by oxygen of the fluorescence from a ruthenium complex. These optrodes were fabricated using Ruthenium-based fluorescent indicator immobilized in a porous glass rod placed at the end of multimode fiber. The light from a blue LED is launched into the optrode via a fiber optic bundle and used as the excitation source. The optrode’s fluorescent emission intensity in the range of 0% to 10% oxygen is measured as a function of time. The measuring system is based on high reliability and low cost. The system consists of four units: 1) temperature compensated oxygen optrodes combined with an optical setup, 2) multipoint sensor communication fiber optic network cable, 3) digital/analogue optoelectronic signal processing unit with built-in micro controller for control of data acquisition and processing, and 4) a laptop computer for data display and storage. In testing, the sensor exhibited excellent response time and reversibility. To qualify the sensors, performed detail investigation for thermal, humidity, temperature, vibration and accelerate testing for life expectancy of harsh environmental of engine section. Extensive networking using MatLab were carried out for lab and actual field demonstrations.
This paper describes the 1st successful Plastic Optical Fiber (POF) cable and Glass Optical Fiber (GOF)
hydrogen detection sensor systems developed for the Boeing Evolved Expandable Lunch Vehicle (EELV)
Delta IV Launch Vehicle harsh environment of engine section. H2 sensors are necessary to monitor the
possible leak of rocket prior launch to avoid explosion, which can be highly dangerous. Due to harsh
environment of launch vehicle, we developed the first combination of 100 m POF and glass fiber H2
sensors. The hydrogen sensor consisted of optrodes distributed at multiple locations along a fiber optic
cable-based network. These hydrogen sensors were used on the Common Booster Core (CBC) of Delta
IV had to perform in temperatures between -18° C and +60° C. The hydrogen sensor sensitive chemistry
was fully reversible and had demonstrated a response to hydrogen gas in the range of 0% to 10% with a
resolution of 0.1 % and a response time of 5 seconds measured at a gas flow rate of 1 cc/mm. The optical
signature of the optrode in the visible spectrum varied proportionally to the local hydrogen gas
concentration. To qualify the POF and fiber optic cables, performed detail investigation for attenuation
loss, thermal, humidity, temperature, vibration and accelerate testing for life expectancy. Extensive
networking using LabView were carried out for lab and actual field demonstrations.
Since the TWA flight 800 accident in July 1996, significant emphasis has been placed on fuel tank safety.
The Federal Aviation Administration (FAA) has focused research to support two primary methods of fuel tank
protection - ground-based and on-board - both involving fuel tank inerting. Ground-based fuel tank inerting
involves some combination of fuel scrubbing and ullage washing with Nitrogen Enriched Air (NEA) while the
airplane is on the ground (applicable to all or most operating transport airplanes). On-board fuel tank inerting
involves ullage washing with OBIGGS (on-board inert gas generating system), a system that generates NEA
during aircraft operations. An OBIGGS generally encompasses an air separation module (ASM) to generate
NEA, a compressor, storage tanks, and a distribution system. Essential to the utilization of OBIGGS is an
oxygen sensor that can operate inside the aircraft's ullage and assess the effectiveness of the inerting
systems. OBIGGS can function economically by precisely knowing when to start and when to stop. Toward
achieving these goals, InnoSense LLC is developing an all-optical fuel tank ullage sensor (FTUS) prototype
for detecting oxygen in the ullage of an aircraft fuel tank in flight conditions. Data would be presented to show
response time and wide dynamic range of the sensor in simulated flight conditions and fuel tank
environment.
This paper describes the successful test of a multi-point fiber optic oxygen sensor system during the static
firing of an Evolved Expandable Launch Vehicle (EELV)/Delta IV common booster core (CBC) rocket
engine at NASA's Stennis Flight Center. The system consisted of microsensors (optrodes) using an
oxygen gas sensitive indicator incorporated onto an optically transparent porous substrate. The modular
optoelectronics and multiplexing network system was designed and assembled utilizing a multi-channel
opto-electronic sensor readout unit that monitored the oxygen and temperature response of the individual
optrodes in real-time and communicated this information via a serial communication port to a remote
laptop computer. The sensor packaging for oxygen consisted of two optrodes - one doped with an
indicator sensitive to oxygen, and the other doped with an indicator sensitive to temperature. The multichannel
oxygen sensor system is fully reversible. It has demonstrated a dynamic response to oxygen gas
in the range of 0% to 100% with 0.1% resolution and a response time of ≤10 seconds. The sensor
package was attached to a custom fiber optic ribbon cable, which was then connected to a fiber optic
trunk communications cable (standard telecommunications-grade fiber) that connected to the
optoelectronics module. Each board in the expandable module included light sources, photo-detectors,
and associated electronics required for detecting oxygen and temperature. The paper illustrates the sensor
design and performance data under field deployment conditions.
This paper describes the successful test of a multi-point fiber optic hydrogen sensor system during the static firing of an Evolved Expandable Launch Vehicle (EELV)/Delta IV common booster core (CBC) rocket engine at NASA's Stennis Flight Center. The system consisted of microsensors (optrodes) using a hydrogen gas sensitive indicator incorporated onto an optically transparent porous substrate. The modular optoelectronics and multiplexing network system was designed and assembled utilizing a multi-channel opto-electronic sensor readout unit that monitored the hydrogen and temperature response of the individual optrodes in real-time and communicated this information via a serial communication port to a remote laptop computer. The sensor packaging for hydrogen consisted of two optrodes -- one doped with an indicator sensitive to hydrogen, and the other doped with an indicator sensitive to temperature. The multi-channel hydrogen sensor system is fully reversible. It has demonstrated a dynamic response to hydrogen gas in the range of 0% to 4% with 0.1% resolution and a response time of less than or equal to 15 seconds. The sensor package was attached to a custom fiber optic ribbon cable, which was then connected to a fiber optic trunk communications cable (standard telecommunications-grade fiber) that connected to the optoelectronics module. Each board in the expandable module included light sources, photo-detectors, and associated electronics required for detecting hydrogen and temperature. The presentation would discuss the sensor design and performance data under field deployment conditions.
Significant emphasis has been placed on fuel tank safety since the TWA flight 800 accident in July 1996. Upon investigation the National Transportation Safety Board (NTSB) determined that the probable cause of the accident was an explosion of the center wing tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank. The Federal Aviation Administration (FAA) has focused research to support two primary methods of fuel tank protection -- ground-based and on-board -- both involving fuel tank
inerting. Ground-based fuel tank inerting involves some combination of fuel scrubbing and ullage washing with Nitrogen Enriched Air (NEA) while the airplane is on the ground (applicable to all or most operating transport airplanes). On-board fuel tank inerting involves ullage washing with OBIGGS (on-board inert gas generating system), a system that generates NEA during aircraft operations. An OBIGGS generally encompasses an air separation module (ASM) to generate NEA, a compressor, storage tanks, and a distribution system. Essential to the utilization of OBIGGS is an oxygen sensor that can operate inside the aircraft's ullage and assess the effectiveness of the inerting systems. OBIGGS can function economically by precisely knowing when to start and when to stop. Toward achieving these goals, InnoSense LLC is developing an all-optical fuel tank ullage sensor (FTUS) prototype for detecting oxygen in the ullage of an
aircraft fuel tank in flight conditions. Data would be presented to show response time and wide dynamic range of the sensor in simulated flight conditions and fuel tank environment.
Optical hydrogen sensors are intrinsically safe since they produce no arc or spark in an explosive environment caused by the leakage of hydrogen. Safety remains a top priority since leakage of hydrogen in air during production, storage, transfer and distribution creates an explosive atmosphere for concentrations between 4% (v/v) - the lower
explosive limit (LEL) and 74.5% (v/v) - the upper explosive limit (UEL) at room temperature and pressure. Being a very small molecule, hydrogen is prone to leakage through seals and micro-cracks. Hydrogen detection in space application is very challenging; public acceptance of hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of cryogenic fluids in spaceport facilities, Launch vehicle industry and NASA are currently relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh several hundred kilograms. An optical sensor system can decrease pay load while monitoring multiple leak locations in situ and in real time. In this paper design of ormsoil approach for developing a completely reversible optical hydrogen sensors for aerospace application is being discussed.
Missiles represent strategic weapons in modern warfare. They are stored prior to deployment, and they need to be kept in flight-ready condition during storage. It is therefore necessary to promptly detect any missile fuel leakage. Intelligent Optical Systems initiated an effort to develop a breakthrough device that combines a long period grating- based chemical sensor with neural network software. These reversible sensors perform real-time measurements of liquid fuel components.
This work evaluates the usefulness of an intracore long period grating (LPG) structure on optical fiber for constructing a fiber-optic chemical sensor. The sensor response relies on the evanescent field interaction of core- guided light with volatile organic compounds (VOCs) surrounding the long period gratings. The LPGs were coated with proprietary chemical indicators having strong affinities for VOCs. The feasibility of this approach was tested by using representative hydrocarbons and halohydrocarbons in parts per thousand to parts per million concentrations. Test results demonstrate that LPGs offer the promise for sensitively detecting VOCs in air, water, and soil matrices.
Optical absorption and electrical conductivity measurements of solution-doped poly-3- octylthiophene (P3OT) films were studied. Chloroform solutions of P3OT were doped with the organic electron-acceptors, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8- tetracyanoquinodimethane (TCNQ); and with the inorganic electron acceptor, ferric chloride (FeCl3). Charge transfer was observed in P3OT solutions doped with FeCl3 and DDQ. TCNQ-doped solutions showed no optical evidence of charge transfer. Thin films of the doped P3OT were examined at various doping levels. Spectroscopic and electrical conductivity measurements of P3OT films, doped with DDQ, TCNQ, and FeCl3 at different doping levels, are presented. Optical absorption measurements provided information on the degree of charge transfer occurring for the various dopants. Electrical conductivity measurements showed that the conductivity of P3OT increased with the various dopants in the order of TCNQ < DDQ < FeCl3, for the same dopant level. Results are discussed in relation to the electrochemical properties of the prepared films.
The use of FOCS for environmental applications, namely, for monitoring spills of HC or leaking underground HC storage tanks, is discussed. The current FOCS design comes in two configurations: the field unit, permanently installed at one or more monitoring sites, and connected to a central monitoring station, and the hand-held unit, designed for rapid on-site evaluation. The sensor's performance in HC vapor at 100 percent relative humidity and at 20 C, and at the vapor-water interface is illustrated.
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