Optical-fibre sensor system for monitoring the performance of the gas–propellant centrifuge separator of a spacecraft

Self Cite

This paper presents a prototype optical-fibre refractometric liquid-level sensor which can access the static and dynamic levels of liquid nitrogen in large cryogenic systems. This version of the sensor is intended for use in various tests of cryogenic systems such as used in rocketry, during the design stage. The sensor employs a vertical linear array of 140 highly sensitive optical-fibre refractometric transducers. The liquid-level measurement range is 1.6 m with a resolution of up to 5 mm. The optical transducers are multiplexed using a matrix-type optical-fibre network which employs a robust level tracking algorithm. This type of sensor can be used for measuring the level of other cryogenic liquids such as liquid hydrogen.

Section: Introductionmentioning

confidence: 99%

An optical-fibre refractometric liquid-level sensor for liquid nitrogen

Romo-Medrano

Khotiaintsev

2006

Self Cite

“…Because an optical probe system is small, it can measure void fractions in complex and small spaces [28,29]. It can also be configured as a multipoint void-fraction sensing system and used to monitor the distribution of void fractions in small two-phase flow areas [30]. The main advantages of optical probes are their rapid response, high spatial resolution, and resistance to changes in pressure and temperature [6].…”

Section: Introductionmentioning

confidence: 99%

Void fraction measurement of lubricant air-oil two-phase flow using a near infrared optical-fiber spectrometer associated with partial least squares regression models

Zhou¹,

Cui²

2022

Motivated by recent research on two-phase flow void fraction measurement, this paper presents a study on void fraction measurements of a lubricant air-oil two-phase flow using a near infrared (NIR) optical-fiber spectrometer associated with partial least squares (PLS) regression models. To overcome the measurement inaccuracy due to interface scattering, this study used PLS regression models to analyse the spectrum of air-oil two-phase flow. First, an NIR optical-fiber spectrometer experimental system was developed. Second, a flow regime analysis was conducted for the bubble flow transition inside the experimental system. Finally, the PLS regression model validations, the void fraction measurement accuracies, and the uncertainties of the experimental system were evaluated and discussed, and the different PLS regression models were compared in detail. The results indicate that the NIR optical-fiber spectrometer combined with the PLS regression model can achieve void fraction measurements of lubricants in air-oil two-phase flow, with a maximum squared correlation coefficient (R2) of 0.981, a minimum Type A uncertainty of 0.039% and a minimum expanded uncertainty of 0.077%.

“…Advancements in optical-fiber sensor systems have allowed the development of monitoring techniques for various industrial applications [18]. The fiber-optic gyroscope (FOG) has many advantages, such as high precision and insensitivity to acceleration.…”

Section: Introductionmentioning

confidence: 99%

Calibration of gyro G-sensitivity coefficients with FOG monitoring on precision centrifuge

Yang

et al. 2017

The advantages of mechanical gyros, such as high precision, endurance and reliability, make them widely used as the core parts of inertial navigation systems (INS) utilized in the fields of aeronautics, astronautics and underground exploration. In a high-g environment, the accuracy of gyros is degraded. Therefore, the calibration and compensation of the gyro G-sensitivity coefficients is essential when the INS operates in a high-g environment. A precision centrifuge with a counter-rotating platform is the typical equipment for calibrating the gyro, as it can generate large centripetal acceleration and keep the angular rate close to zero; however, its performance is seriously restricted by the angular perturbation in the high-speed rotating process. To reduce the dependence on the precision of the centrifuge and counter-rotating platform, an effective calibration method for the gyro g-sensitivity coefficients under fiber-optic gyroscope (FOG) monitoring is proposed herein. The FOG can efficiently compensate spindle error and improve the anti-interference ability. Harmonic analysis is performed for data processing. Simulations show that the gyro G-sensitivity coefficients can be efficiently estimated to up to 99% of the true value and compensated using a lookup table or fitting method. Repeated tests indicate that the G-sensitivity coefficients can be correctly calibrated when the angular rate accuracy of the precision centrifuge is as low as 0.01%. Verification tests are performed to demonstrate that the attitude errors can be decreased from 0.36° to 0.08° in 200 s. The proposed measuring technology is generally applicable in engineering, as it can reduce the accuracy requirements for the centrifuge and the environment.