Droplet concentration in water spray using short-range elastic backscatter lidar

Area of Science:

• Fluid dynamics
• Optical physics
• Aerosol science

Background:

• Accurate measurement of droplet concentration in sprays is crucial for various industrial applications.
• Remote sensing techniques offer non-intrusive alternatives to traditional measurement methods.

Purpose of the Study:

• To propose and validate a novel experimental method for remotely measuring droplet concentration in water sprays.
• To develop a specific calibration technique for lidar radiometric constant determination.
• To formulate a new lidar constant using spray transmittance and particle size distribution.

Main Methods:

• Utilized a short-range elastic backscatter lidar system.
• Developed a calibration technique to determine the lidar radiometric constant.
• Proposed a new lidar constant formulation incorporating total spray transmittance and laser diffraction-measured particle size distribution.
• Compared lidar-derived concentrations with laser diffraction measurements.

Main Results:

• Successfully converted lidar signals into attenuated backscatter signals and aerosol properties.
• Estimated average volume concentrations ranging from 10^8 to 10^9 droplets per cubic meter.
• Achieved comparable results to laser diffraction, particularly for sprays with larger droplets (Sauter mean diameter > 50 µm).

Conclusions:

• The proposed lidar method provides a viable approach for remote measurement of water spray droplet concentration.
• The novel calibration and lidar constant formulation enhance the accuracy of aerosol property retrieval.
• This technique shows promise for applications requiring non-intrusive spray characterization.