Millimeter-wave tomography of dense particle clouds

Area of Science:

• Engineering
• Physics
• Fluid Dynamics

Background:

• Dense multiphase flows are challenging to analyze with traditional optical methods.
• Accurate particle concentration measurement is crucial for industrial processes and aerospace applications.

Purpose of the Study:

• To present a novel millimeter-wave interferometric tomographic instrument for quantitative particle concentration measurements.
• To evaluate measurement uncertainty and error contributions.
• To demonstrate the instrument's capabilities in a relevant experimental setting.

Main Methods:

• Utilized a 77-GHz automotive radar combined with passive reflectors for path-integrated measurements.
• Employed an inverse Abel transform to reconstruct local concentration distributions.
• Conducted experiments simulating plume-surface interaction relevant to space landings.

Main Results:

• Achieved quantitative particle concentration measurements exceeding 10 particles/mm³.
• Demonstrated high temporal resolution of 10 kHz.
• Quantified cumulative concentration errors at -9 dB.

Conclusions:

• Millimeter-wave radar tomography is effective for spatially resolved particle concentration in dense, particle-laden flows.
• The instrument's high temporal resolution is suitable for transient phenomena.
• This technique has broad applicability in aerospace, chemical processing, and other industries.