Measuring method of airfoil surface boundary layer transition position based on distributed temperature-sensitive optical fiber

Abstract

A method for measuring the transition position of the airfoil surface boundary layer based on distributed temperature-sensitive optical fibers. The temperature optical fiber is laid on the surface of the airfoil model, and the distributed temperature-sensitive optical fiber is used to measure the influence of the temperature distribution of the airflow passing the surface of the object on the flow transition. The method of judging the position. Use a backlight reflectometer to measure the Rayleigh backscattered light in the optical fiber to obtain loss and fiber length information. After adding a sensing module, ordinary single-mode optical fiber can be used as a sensor to achieve 1cm spatial resolution and 0.1°C temperature within 70m. Resolution of temperature for low frequency testing. Compared with other transition measurement technologies, both the temperature resolution and the spatial accuracy of transition position judgment are improved. The present invention does not need to embed a dynamic pressure sensor on the surface of an object like dynamic pressure judgment transition, and is easier to implement than transition measurement and judgment methods such as wall shear stress measurement and infrared thermal imager, and has higher spatial resolution.

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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