Outward-turning type coaxial cylinder viscometer of hollow cylinder type optical fiber Bragg grating

Abstract

The invention provides an outward-turning type coaxial cylinder viscometer of a hollow cylinder type optical fiber Bragg grating, comprising a torsion measurement grating, a temperature compensation grating, an elastic hollow cylinder, an L-shaped temperature compensator, a stator and a viscometer measuring system which is composed of a spectrum analyzer, an ASE light source, a coupler and an optical fiber; the inner wall of the elastic hollow cylinder is pasted with the torsion measurement grating and the L-shaped temperature compensator, a long side of the compensator is pasted with the temperature compensation grating. According to the measured value of torsion and temperature sensitivity difference of the torsion measurement grating and the temperature compensation grating, the compensation of torque measurement disturbed by temperature fluctuation is realized by adopting differential operation, so as to realize accurate measurement of the torque. One end of the optical fiber is respectively connected with the spectrum analyzer and the ASE light source by the coupler, the other end thereof is connected with the optical fiber Bragg grating; wideband laser emitted by the ASE light source enters into the optical fiber Bragg grating, viscosity number is directly read out by wavelength displacement operation through an embedded computer of the analyzer. The sensor is suitable for measuring the viscosity of various fluids.

Description

technical field [0001] The invention relates to a hollow cylinder type optical fiber Bragg grating external rotation coaxial cylinder viscometer, which belongs to the technical field of optoelectronic measurement. Background technique [0002] Viscosity is a measure of the internal friction that occurs between molecules when a liquid is moved by an external force. At present, the strain sensor commonly used to measure viscosity is a sensor that indirectly measures viscosity by measuring the strain (torque) of various elastic elements. Elastic elements generally have a sheet shape, a rod shape, a wire shape, and a disk shape. Such as Wang Xiaobo, Wu Jiangtao, Liu Zhigang and others published the paper "Improvement of Vibrating Disk Viscometer and Experimental Research on R152a Gas Phase Viscosity" ["Journal of Xi'an Jiaotong University", 2008, 42(11)], the elastic element in the paper is torsion wire, The material is titanium-nickel alloy wire. Due to the unique electrical ...

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Problems solved by technology

Paper by Zhang Weigang, Kai Guiyun, Zhao Qida, Yuan Shuzhong, Dong Xiaoyi et al. "Fiber Bragg Grating Linear Torsion Sensor Free from Temperature Effects", ["China Laser", 2003, 30(1)] Applying Fiber Bragg Grating to Torsion Sensor , this paper bonded solid rods and hollow rods of organic materials as strain rods for torsion sensors, but this paper only studied the torque measurement, and did not further measure the viscosity of the liquid; and because of the The introduced torsion measuring grating is directly pasted on the outer wall of the elastic hollow cylinder, so it is easy to be damaged, and there is a problem of packaging protection, and because it uses a single grating to realize the torsion sensing measurement that is not affected by temperature, and the two sides of the torsion beam boundary are not Completely rigid bonding, so that the strain of the fiber Bragg grating pasted there is non-step but continuous. The difference in strain distribution on both sides of the boundary between the solid beam and the hollow beam will inevitably lead to double peaks and overlapping areas, resulting in two There is a certain light reflection distribution between the peaks, resulting in unequal intensities of the two peaks, which does not completely eliminate the wavelength shift caused by external temperature changes (there is a measurement error), and there are blind spots in the measurement, which are difficult to distinguish (that is, the measurement error is difficult to eliminate)

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