Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping

Area of Science:

• Fluid Dynamics
• Measurement Science

Background:

• Computational fluid dynamics (CFD) code validation requires high-resolution velocity and temperature data.
• Traditional temperature sensors lack the spatial and temporal resolution needed for rigorous CFD validation.
• Optical measurement techniques provide high-resolution velocity data but not temperature data.

Purpose of the Study:

• To demonstrate the implementation and practical considerations of a distributed temperature sensor based on Rayleigh scattering for CFD code validation.
• To provide guidance on sensor selection, installation, and operation for high-data-density temperature measurements in fluid dynamics experiments.

Main Methods:

• Implementation of a Rayleigh scattering-based distributed temperature sensor.
• Conducting a thermal mixing experiment with two air jets.
• Developing criteria for optical fiber selection and installation procedures.
• Performing sensor baselining against an absolute temperature standard.

Main Results:

• The Rayleigh scattering sensor achieved high spatial and temporal resolution temperature measurements.
• Identified practical challenges including sensitivity to strain, humidity, and flow-induced vibrations.
• Demonstrated effective baselining for accurate temperature readings.

Conclusions:

• Distributed temperature sensing using Rayleigh scattering is a viable technique for high-resolution measurements in fluid dynamics.
• Careful consideration of sensor handling, installation, and environmental factors is crucial for accurate measurements.
• This technology offers a valuable tool for enhancing CFD code validation and similar applications.