X-probe flow sensor using self-powered active fiber Bragg gratings

Abstract A thermal X-probe sensor using self-powered fiber Bragg gratings (FBGs) has been developed to measure both magnitude and direction of two-dimensional gas flows based on convective heat transfer principles. The flow sensor employs two cross-mounted FBGs (X-probe), which are heated by light carried in the same fiber that contains FBGs. When the power light is turned off, the FBGs are used to measure the temperature of the surrounding fluids. When the power light is turned on, in-fiber diode laser light is leaked out of the fiber and is absorbed by the surrounding metallic coating to raise the temperature of the fiber gratings. The convective heat removal by incoming gas flows changes the temperature of the fibers and, as a result, the resonance wavelengths of the heated FBGs are shifted. The FBG sensor is calibrated for air flows of speeds from 0.3 to 20 m/s and a yaw angle from −45° to 45°, respectively. Air flow tests indicate the flow speed and the direction deduced from the sensors are in good agreement with the actual flow conditions confirming the feasibility of the present sensor.

[1]  A. W. van Herwaarden,et al.  High-sensivity 2-D flow sensor with an etched thermal isolation structure , 1990 .

[2]  Richard M. Lueptow,et al.  Computer-aided calibration of X-probes using a look-up table , 2004 .

[3]  Lennart Löfdahl,et al.  A sensor based on silicon technology for turbulence measurements , 1989 .

[4]  Johan H. Huijsing,et al.  Integrated flow friction sensor , 1988 .

[5]  Werner J. Blau,et al.  Hybrid light-emitting polymer device fabricated on a metallic nanowire array , 2005 .

[6]  Nam-Trung Nguyen,et al.  Micromachined flow sensors—a review , 1997, Flow Measurement and Instrumentation.

[7]  B. W. Oudheusden.  Silicon thermal flow sensors , 1992 .

[8]  Kevin P. Chen,et al.  Self-heated fiber Bragg grating sensors , 2005 .

[9]  H. H. Bruun,et al.  Hot-Wire Anemometry: Principles and Signal Analysis , 1996 .

[10]  L. Chua,et al.  Calibration ofX-probes for turbulent flow measurements , 1988 .

[11]  G. Stemme.  A monolithic gas flow sensor with polyimide as thermal insulator , 1986, IEEE Transactions on Electron Devices.

[12]  O. Tabata,et al.  Fast-response silicon flow sensor with an on-chip fluid temperature sensing element , 1986, IEEE Transactions on Electron Devices.

[13]  K.P. Chen,et al.  Controlling fiber Bragg grating spectra with in-fiber diode laser light , 2004, IEEE Photonics Technology Letters.

[14]  Yu-Chong Tai,et al.  MEMS flow sensors for nano-fluidic applications , 2000, Proceedings IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems (Cat. No.00CH36308).

[15]  Petar Vukoslavcevic,et al.  A method to calibrate a hot-wire X-probe for applications in low-speed, variable-temperature flow , 2003 .