Remote gas sampling with a swirl air stream

Area of Science:

• Fluid dynamics
• Analytical chemistry
• Remote sensing

Background:

• Remote gas sampling techniques often face limitations due to low analytical flow rates of gas analyzers.
• Achieving effective vortex core formation in swirl sampling streams presents practical challenges.
• Existing methods struggle with sampling distance and maintaining adequate pressure for analysis.

Purpose of the Study:

• To address limitations in remote gas sampling for mass spectrometry.
• To investigate the adjustment of vortex and sampling flows for atmospheric pressure ionization mass spectrometry.
• To optimize the formation of a composite swirl vortex core for enhanced gas analysis.

Main Methods:

• Experimental investigation of swirl air streams for remote gas sampling.
• Utilizing a mass spectrometer with atmospheric pressure ionization for diethylanyline vapor analysis.
• Modifying sampling flow dynamics by introducing an additional coaxial flow (Q(add)).

Main Results:

• Additional sampling flow (Q(add)) facilitates the formation of a vortex core with high tangential velocity and low axial pressure.
• An optimal ratio of vortex flow (Q(vortex)) to additional flow (Q(add)) of 1.3 was determined (Q(vortex)/Q(add)=1.3).
• The composite vortex model showed satisfactory agreement with experimental findings.
• Sampling distance and area are primarily influenced by geometric sampler parameters.

Conclusions:

• The coaxial additional sampling flow is crucial for establishing the desired vortex core conditions.
• The optimal flow ratio enhances both gas dynamic properties and sampling efficiency.
• Vortex sampling effectively focuses the sample within the vortex core, preventing dilution and improving analysis accuracy.