Measurement method of transition position of airfoil surface boundary layer based on distributed thermosensitive optical fiber

Abstract

The invention discloses a measurement method of a transition position of airfoil surface boundary layer based on a distributed thermosensitive optical fiber. The method comprises the steps of laying a temperature optical fiber on the surface of an airfoil model, and measuring the temperature distribution of airflow flowing through the surface of an object through a distributed thermosensitive optical fiber to judge a flow transition position. Back Rayleigh scattering light in the optical fiber is measured through a backlight reflexometer, and after loss and optical fiber length information are obtained and a sensing module is added, a common monomode optical fiber serving as a sensor can be used to perform temperature low-frequency testing reaching 1cm space resolution and 0.1-DEG C temperature resolution within a 70m range. Compared with other transition measurement technology, both the temperature resolution and the special accuracy judged by transition position are enhanced. The method has the advantages that a dynamic pressure sensor is not required to be embedded on the surface of an object for judging transition through dynamic pressure, the method is easier to realize than wall shear stress measurement and transition measurement judgment method through a thermal infrared imager, and the spatial resolution is high.

Description

technical field [0001] The invention relates to an object surface flow transition measurement technology, in particular to a method for judging the flow transition position by using a distributed temperature-sensitive optical fiber to measure the temperature distribution of the airflow flowing through the object surface. Background technique [0002] Transition is the transition process of the fluid boundary layer on the surface of the object from laminar flow to turbulent flow. The transition problem of the fluid boundary layer is still one of the difficult problems in the study of fluid mechanics. The transition process is very complex, including destabilization of layers, appearance and amplification of T-S wave, development of three-dimensional disturbance and formation of flow vortex, high-frequency oscillation and turbulent spot caused by secondary destabilization of flow, expansion of turbulent spot and development into complete turbulence A series of complex unsteady...

AI Technical Summary

Problems solved by technology

Traditional temperature measurement methods such as thermocouples and platinum resistance thermometers can achieve single-point temperature testing, but if they are fixed on the skin or model surface, they will have a great impact on the aerodynamic shape; recently developed infrared thermometers and thermal imagers can achieve Non-contact measurement, but the temperature resolution is ±2°C, and the test results will have large deviations under air flow disturbance

[0003] Domestic and foreign patent searches have not yet used temperature-sensitive optical fiber to measure the surface temperature of objects and then determine the flow transition position.

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