April 3, 2023

A new tomographic absorption spectroscopy (TAS) platform using two-dimension (2D) contour imaging to display H2O mole fraction distribution from the laminar jet into ambient air.

With the concern over the changing climate and the rise of pollutants in the air, precise and effective monitoring is needed for efficient reduction of greenhouse and hazardous gases in industrial production, transportation, and propulsion.

Researchers from the School of Aeronautics and Astronautics in Chengdu, China and the Chinese University of Hong Kong have developed a jet flow, TAS platform to study H2O transport in a non-reactive jet flow with various conditions. By combining tomography and absorption spectroscopy techniques with a laser with center wavelength of 1368.598 nm, two-dimension contour imaging was created to display H2O mole fraction distribution from the laminar jet into ambient air. The reconstructed distributions at different heights above the jet flow nozzle, as well as the 2D contour, matched well with and were validated with computational fluid dynamics (CFD) simulations.

A distributed-feedback (DFB) laser served as the TAS laser source for the investigation of H2O transport in a dry laminar jet. Wavelength Electronics’ LDTC0520 laser diode and temperature controller provided stable drive current and temperature control for the DFB laser with noise of 7.5 µA RMS, high temperature accuracy and 0.005°C stability, ensuring minimal noise was added to the photodetector after TAS.

This research shows the great potential that TAS has in the field of mass transfer and scalar field of gaseous flows.

The complete case study is available as CS-LDTC12.

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