Self-calibrating method and system for laser-induced-fluorescence-based speed measurement

Abstract

The invention discloses a self-calibrating method and system for laser-induced-fluorescence-based speed measurement. The self-calibrating method comprises: exiting laser is modulated to apply two beams of laser in opposite directions in a to-be-measured flow field to a to-be-measured particle in the to-be-measured flow field; the strength of a fluorescence signal from the excited to-be-measured flow field on the laser path is measured to obtain a practical-measuring fluorescence spectrum profile; and fitting is carried out on the practical-measuring fluorescence spectrum profile to obtain a first fluorescence spectrum profile and a second fluorescence spectrum profile that correspond to the two beams of laser in opposite directions and numerical average value solving is carried out on central frequency points of the first fluorescence spectrum profile and the second fluorescence spectrum profile to obtain a laser frequency corresponding to an absolute speed zero point. Therefore, in-situ calibration is realized; and separate construction of a reference plasma source is not required. The calibration plan is simplified and the measuring cost is saved; a measuring error caused by a Stark effect under the circumstance of unequal densities between the reference plasma source and a to-be-measured plasma can be eliminated; and the measuring precision is improved.

Description

technical field [0001] The invention relates to the field of flow field velocity measurement, in particular to a self-calibration method and system for laser-induced fluorescence velocity measurement. Background technique [0002] Using laser induced fluorescence (Laser induced fluorescence, LIF) to measure the Doppler effect of selected particles in the moving fluid, and then obtain the particle velocity distribution function of the target flow field, is a non-contact, high sensitivity, and high selectivity technology. It has a very broad application prospect in the technical field involving plasma diagnosis (material processing, flow control, space electric rocket propulsion). In order to obtain the absolute value of the measured speed, it is necessary to calibrate the zero point of the absolute speed during the LIF speed measurement, that is, to obtain the corresponding laser frequency when the absolute speed is zero. [0003] At present, the element lamp method is used ...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a self-calibration method and system for laser-induced fluorescence velocimetry to solve the problem of high measurement cost and low measurement accuracy caused by using the element lamp method to calibrate the laser frequency corresponding to the absolute velocity zero point in the existing laser-induced fluorescence velocimetry. limited technical issues

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