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Results for “fiberoptics”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Fiberoptics for propulsion control system

In aircraft systems with digital controls, fiberoptics has advantages over wire systems because of its inherent immunity to electromagnetic noise (EMI) and electromagnetic pulses (EMP). It also offers a weight benefit when metallic conductors are replaced by optical fibers. To take full advantage of the benefits of optical waveguides, passive optical sensors are also being developed to eliminate the need for electrical power to the sensor. Fiberoptics may also be used for controlling actuators on engine and airframe. In this application, the optical fibers, connectors, etc. will be subjected to high temperature and vibrations. This paper discussed the use of fiberoptics in aircraft propulsion systems together with the optical sensors and optically controlled actuators being developed to take full advantage of the benefits which fiberoptics offers. The requirements for sensors and actuators in advanced propulsion systems are identified. The benefits of using fiberoptics in place of conventional wire systems are discussed as well as the environmental conditions under which the optical components must operate.

Baumbick, R. J.↗
NASA NTRS1992

Fiberoptic characteristics for extreme operating environments

Fiberoptics could offer several major benefits for cryogenic liquid-fueled rocket engines, including lightning immunity, weight reduction, and the possibility of implementing a number of new measurements for engine condition monitoring. The technical feasibility of using fiberoptics in the severe environments posed by cryogenic liquid-fueled rocket engines was determined. The issues of importance and subsequent requirements for this use of fiberoptics were compiled. These included temperature ranges, moisture embrittlement succeptability, and the ability to withstand extreme shock and vibration levels. Different types of optical fibers were evaluated and several types of optical fibers' ability to withstand use in cryogenic liquid-fueled rocket engines was demonstrated through environmental testing of samples. This testing included: cold-bend testing, moisture embrittlement testing, temperature cycling, temperature extremes testing, vibration testing, and shock testing. Three of five fiber samples withstood the tests to a level proving feasibility, and two of these remained intact in all six of the tests. A fiberoptic bundle was also tested, and completed testing without breakage. Preliminary cabling and harnessing for fiber protection was also demonstrated. According to cable manufacturers, the successful -300 F cold bend, vibration, and shock tests are the first instance of any major fiberoptic cable testing below roughly -55 F. This program has demonstrated the basic technical feasibility of implementing optical fibers on cryogenic liquid-fueled rocket engines, and a development plan is included highlighting requirements and issues for such an implementation.

Delcher, R. C.↗
NASA NTRS1992

Fiberoptic sensors for rocket engine applications

A research effort was completed to summarize and evaluate the current level of technology in fiberoptic sensors for possible applications in integrated control and health monitoring (ICHM) systems in liquid propellant engines. The environment within a rocket engine is particuarly severe with very high temperatures and pressures present combined with extremely rapid fluid and gas flows, and high-velocity and high-intensity acoustc waves. Application of fiberoptic technology to rocket engine health monitoring is a logical evolutionary step in ICHM development and presents a significant challenge. In this extremely harsh environment, the additional flexibility of fiberoptic techniques to augment conventional sensor technologies offer abundant future potential.

Ballard, R. O.↗
NASA NTRS1982

Status of fiberoptics technology for propulsion control systems

Optical sensors and optically controlled actuators for use in airbreathing engine control systems are discussed. The environmental conditions in which the aircraft will operate require the fiberoptic cables and optical connectors to perform reliably at temperatures over the -55 C to 260 C range. The status of fiberoptics technology for operation in this environment is reviewed.

Baumbick, R. J.↗
NASA NTRS1989

Fiberoptics for liquid propellant rocket engine environments

Interest is increasing in the use of fiberoptics on liquid-fueled rocket engines in recognition of their immunity to lightning and EMI, light weight, high-frequency response, and the possibility offered by optical technologies to measure additional important engine parameters for which present measurement methods are impractical. This paper discusses the requirements to be placed on fiberoptics applied to liquid-fueled rocket engines; identifies manufacturers of fibers that appear to have promise for the harsh rocket engine applications; and summarizes information on the characteristics of these fibers obtained from the manufacturers, program testing, and the general literature.

Delcher, R.↗
NASA NTRS1988

1.3-micron Ku-band fiberoptic transmission system for satellite communications and antenna remoting

Microwave fiberoptic transmission system provides numerous advantages for satellite communications terminals and antenna remoting. This paper described a 1.3-micron, 6-15 GHz, 1-km fiberoptic system design and performance. The microwave characteristics of the laser diode photodetector are discussed in detail. The preliminary measured system signal-to-noise ratio (SNR) are 110-120 dB/Hz in the frequency range of 6-15 GHz. A 20 to 30 dB SNR improvement is achievable when coherent detection and PD impedance matching are employed.

Pan, J. J.↗
NASA NTRS1993

High-Dynamic Range Fiberoptic Links for Antenna Remoting Applications

In recent years, the performance and cost effectiveness of analog fiberoptic communication systems have improved so that many applications including antenna remoting which requires high dynamic range can now benefit from the many advantages of fiber optics.

high speed microwave fiberoptic systems DFB Fabry-↗
NASA NTRS1983

Fiberoptics technology and its application to propulsion control systems

Electro-optical systems have many advantages over conventional electrical systems. Among these are optics' insensitivity to electro-magnetic interference, good electrical isolation and the ability to make measurements in highly explosive areas without risk. These advantages promise to help improve the reliability of future aircraft engine control systems which will be entirely electronic digital. To improve the reliability of these systems, especially against lightning strikes, passive, optical, sensors and fiberoptic transmission lines are being considered for use in future engine systems. Also under consideration are actuators which receive their command signals over fiber optic cables. This paper reviews concepts used for optical instrumentation and actuation systems and discusses work being done by NASA Lewis Research Center in this area.

Baumbick, R. J.↗
NASA NTRS1991

A dual-eigenstate polarization preserving fiberoptic sensor

A dual-eigenstate polarization preserving fiberoptic sensor is tested, in which each eigenstate in a polarization preserving fiber forms an interferometer which could measure the temperature and the strain simultaneously. The temperature and strain coefficients for different polarization fibers are measured at the room temperature, indicating that there exist differences in temperature coefficients between two eigenstates in a polarization preserving fiber. The different temperature effects from those eigenstates make it possible to perform the temperature measurement and/or temperature compensation.

Yu, Dong X.↗
NASA NTRS1991

Fiberoptic sensing technique employing RF modulated interferometry

A detection technique for intensity type fiberoptic sensors is described. It employs a multimode fiber interferometer, with the sensor in one arm, excited by an LED modulated at RF frequencies f(o) and 2f(o). Sensor induced changes in intensity result in corresponding changes in the ratio of the detected f(o) and 2f(o) signals, thus eliminating various common mode effects. Results obtained with a displacement sensor and preliminary results from a pressure sensor illustrate the capabilities of this technique.

Eustace, John G.↗
NASA NTRS1983

Fiberoptics technology and its application to propulsion control systems

Current work on optical sensors and optically controlled actuators for use in air-breathing engine control systems is reviewed with particular reference to the design and operation of several new fiber-optic devices. These include a tachometer, a rotary position encoder, a Fabry-Perot interferometer and a rare-earth sensor for measuring engine gas temperatures, a high-temperature photoswitch designed for the range -55 to 260 C, and optical cables and connectors. The advantages of optics over conventional wire systems used for sensing and actuator control are briefly discussed.

Baumbick, R. J.↗
NASA NTRS1988

The role of fiberoptics in remote temperature measurement

The use of optical fibers in conjunction with infrared detectors and signal processing electronics represents the latest advance in the field of non-contact temperature measurement and control. The operating principles and design of fiber-optic radiometric systems are discussed and the advantages and disadvantages of using optical fibers are addressed. Signal processing requirements and various infrared detector types are also described. Several areas in which infrared fiber-optic instrumentation is used for temperature monitoring and control are discussed.

Vanzetti, Riccardo↗
NASA NTRS1989

Integrated controls and health monitoring fiberoptic shaft monitor

Recent work was performed on development optical technology to provide real time monitoring of shaft speed, shaft axial displacement, and shaft orbit of the OTVE hydrostatic bearing tester. Results show shaft axial displacement can be optically measured (at the same time as shaft orbital motion and speed) to within 0.3 mills by two fiber optic deflectometers. The final results of this condition monitoring development effort are presented.

Coleman, P.↗
NASA NTRS1989

Design procedures of high speed low loss fiberoptic links

Losses in short-haul broadband fiber-optic links are primarily due to many characteristics of electrooptic devices. In particular, electrical mismatch at the electrical/optical interfaces have been the dominant source of loss. Losses can be significantly reduced and link performance enhanced by reactive matching of the laser and detector modules. The steps in the design of low-loss fiber-optic links are presented, which are on the basis of (1) two-tier deembedding of laser and photodiodes from test fixtures and (2) reactively matching them to a standard 50-ohm system. These concepts are demonstrated by design of a link operating at 0.5 to 1 GHz using reactively matched optical transmitter and receiver modules.

Daryoush, A. S.↗
NASA NTRS1990

Determination of the durability of the fiberoptics in rocket engine environments

The results of a testing program in which selected optical fibers were exposed to extreme environments representative of those experienced on rocket engines are discussed. Included in the experiment are cold-bend testing, a moisture embrittlement test, a thermal cycling test, temperature extremes testing, vibration testing, and shock testing. Two of the fibers selected, the titanium-carbide-coated and the aluminum-jacketed silica samples succeeded in passing all the tests without a failure.

Delcher, R.↗