Lin Ye

Novel light-leaking optical fiber liquid-level sensor for aircraft fuel gauging

Abstract. We present a novel light leaking optical fiber liquid level sensor for aircraft fuel measuring systems that is based on the side-emitting optical fiber. In operation, the fiber is bent as a spiral and inserted into the liquid, then the conducting light in the fiber will be scattered and transformed to be cladding mode and radiation mode. The radiation mode power in the scattering light is determined by the ambient refractive index. Since more power is lost in liquids than in the air, the output power of the sensor will monotonically decrease while the liquid level increases. The fiber is bent as a spiral to increase the sensor’s sensitivity. A laboratory prototype with a range of 1 m, a radius of 14 mm, and a screw pitch of 15 mm has been built and successfully demonstrated in water level measurement. The sensor’s response to liquid level is presented and shown to be consistent with the theory.

Continuous fuel level sensor based on spiral side-emitting optical fiber

A continuous fuel level sensor using a side-emitting optical fiber is introduced in this paper. This sensor operates on themodulation of the light intensity in fiber, which is caused by the claddings acceptance angle change when it is immersed in fuel. The fiber is bent as a spiral shape to increase the sensors sensitivity by increasing the attenuation coefficient and fibers submerged length compared to liquid level. The attenuation coefficients of fiber with different bent radiuses in the air and water are acquired through experiments. The fiber is designed as a spiral shape with a steadily changing slope, and its response to water level is simulated. The experimental results taken in water and aviation kerosene demonstrate a performance of 0.9m range and 10mm resolution.

A Fiber-Optic Solution to Aircraft Icing Detection and Measurement Problem

Aviation industry has a serious problem with ice, which forms on the aircraft that could endanger the crew and vehicle. To solve this problem, fiber-optic technology is employed to present a novel ice detection and measurement system. Comparing with existing ice detection system, this system does not require the measurement of ambient air temperature and liquid water content to determine icing condition. Instead, it detects the ice thickness and its rate directly. Moreover, this detection system also handles the problem of flush installation. As an application of the ice measurement technology, an experiment platform was set up. Performance results achieved demonstrate that the fiber-optic ice detection and measurement system has the potential to become a critical tool in addressing in-flight icing problem.

Ice type detection using an oblique end-face fibre-optic technique

This paper reports on a novel, compound fibre-optic ice sensor consisting of two source fibre bundles and two signal ones. All the bundles had oblique fibre end-faces that were not perpendicular to the fibre axis. Dynamically icing experiments in an icing wind tunnel showed that with increasing thickness of ice accreted on the sensor, one group, comprising the first source and signal fibre bundles, output decreasing signal for glazed ice, increasing signal for rime ice, and constant signal for mixed ice, while the other group, comprising the second source and signal bundles, output constant signal for rime ice and decreasing signal for glazed or mixed ice. The different ice-growth curves are caused by different optical intensity distributions in the fibres for different ice types and thus can be used to accurately measure the ice type and thickness. This sensor is competitive in ice detection, especially identification of ice type in the aviation industry.

Research on the Application of Neural Network in Diaphragm Icing Sensor Fault Diagnosis

As the core component of the Icing Detection System of aircrafts, the reliability of Diaphragm Icing Sensor is a key factor for the ice detection system to work normally. This paper makes use of Neural Network and Autoregressive Exogeneous Model (ARX) to set up the output prediction model of the diaphragm icing sensor. Compare the predicted output of the model with the actual output to diagnose sensor faults of the sensor. According to the data acquiring from our experiment platform of Diaphragm Icing Sensor, it has been proved that this method is effective for fault diagnosis of the Diaphragm Icing Sensor.

Fiber-Optic Ice Detection System for Aeroplane Application

Ice detection technology has changed very little over the last 30 years, relying on indirect methods based on measurement of ambient air temperature and liquid water content to determine icing condition. This paper presents a novel ice detection system offering a viable solution to the problem of detecting ice thickness and its rate directly, based on the scattering and reflection of light. With the platform designed, the encouraging experiment results of this work are presented and discussed. On the basis of above, he arranged a set of fibers in a linear array equidistantly at a pitch of 1mm (5), which are capable of measuring the thickness of ice and its accretion rate. However, the final signal obtained in the experiments is light intensity, which is difficult to be processed, and no signal processing result has been reported yet. In this paper, we transformed the light intensity signal into voltage signal which is proportional to the ice thickness. This paper is organized as follows. In section Ⅱ , configuration design of the sensor probe is described. In section Ⅲ , based on the analysis of light transmission properties, the principle of measurement is presented. A detailed description of the system is included. The experiment and results discussion are provided in section Ⅳ. Concluding remarks are collected in section Ⅴ.

An optical fiber point liquid level sensor

An optical fiber sensor to accurately judge the level of a point is presented in this paper. Three fibers are used in the sensor, one as the source to emit infrared light, and the others as the differential inputs to absorb the scattering of light. Adopting a differential structure of dual signal fibers helps removing the interference of external environment and the change of the intensity of the light source. When the sensor contacts the liquid, the emitted light will be scatted by the liquid so that the output voltage will have significant difference from it when the sensor is above the liquid. A 45 degree oblique end-face of fibers is not just used to reduce the adhesion of liquid but also can increase discrepancy between differential inputs due to different scattered light intensity at different position, and then enhance the sensitivity. Base on this point, the optical fiber point liquid level sensor is designed and its working performance is investigated by experiments. The experimental results indicated stability, accuracy and excellent performance in the use of this sensor to measure the status of liquid level. And the safety will be ensured for the characteristic of fiber and excellent electrical isolation.

A Side-Coupled Optical-Fiber Liquid Level Sensor

A side-coupled optical-fiber liquid level sensor is proposed to realize intrinsically safe measurement to liquid level in flammable environments. The sensor consists of two parallel side-polished fibers is based on the different coupling coefficient between the fibers in different media according to the Fresnel equation. One of the fibers is for emitting and the other is for receiving, and a reflector is attached to the end of the fibers to enhance the power of light. The power of the light from the top of receiving fiber is measured by the signal processing circuit which is mainly organized by an instrumentation amplifier and a correlator. This sensor is fabricated in the laboratory and the results of the experiments show good performance. It is demonstrated that the sensor is safe and sensitive, but there is still a lot of work to do before its commercial usage.

Enlargement of Measurement Range in a Fiber-Optic Ice Sensor by Artificial Neural Network

Artificial neural network (ANN) isemployed to present a fiber-optic ice sensor (FOIS) with wide measurement range. Comparing with existing FOIS signal processing methods, this approach is not limited by the double-valued problem of output curve. Instead, it performs a measurement range from front-slope areas to back-slope areas. Moreover, this approach also handles the nonlinear problem of the sensor. As an application of the ANN, a calibration experiment platform is set up. The training samples are employed to train the ANN, and the testing samples are applied to surveil the predict ability of the ANN. The results obtained demonstrate the applicability of the proposed approach.

Modelling and experimental study on the fiber-optic ice sensor

The theoretical models of fiber-optic ice sensor (FOIS) which are applicable to various geometrical and arrangement parameters are presented on the basis of a single fiber pair model. The theoretical characteristics of various parameters are simulated and compared by using MATLAB. Moreover, an experiment on a concentric fiber arrangement sensor with processing circuit is carried out. It is demonstrated that the results obtained enable to predict the performances of sensor with various parameters, and pave the way for optimized design.