Measuring spray droplet sizes from vibrations induced by spray droplet impacts

A system of predicting one or more spray droplet size statistics, comprising:

• a vibration sensor to sense vibration induced by impacts of spray droplets on a substrate, wherein the spray droplets are emitted by a nozzle positioned a predetermined distance from the substrate;
• a data acquisition device and/or microcontroller operatively connected to receive an output signal from the vibration sensor to acquire vibration data in the time domain;
• a computing device operatively connected to the data acquisition device to receive the vibration data in the time domain and to perform a method comprising
• transforming the vibration data in the time domain to power data in the frequency domain,
• calculating a cumulative power magnitude based on the power data in the frequency domain over the data acquisition frequency,
• predicting one or more spray droplet size statistics based on the cumulative power magnitude at a predetermined frequency by applying a prediction model correlating cumulative power magnitude at the predetermined frequency and the one or more spray droplet size statistics.

A computer program product for predicting one or more spray droplet size statistics, the computer program product comprising a computer readable storage medium having program code embodied therewith, the program code executable by one or more processors, to perform a method comprising:

• sensing vibration induced by impacts of spray droplets on a substrate to acquire vibration data in the time domain, wherein the spray droplets are emitted by a nozzle positioned a predetermined distance from the substrate;
• transforming the vibration data in the time domain to power data in the frequency domain;
• calculating a cumulative power magnitude based on the power data in the frequency domain over the data acquisition frequency;
• predicting one or more spray droplet size statistics based on the cumulative power magnitude at a predetermined frequency by applying a prediction model correlating cumulative power magnitude at the predetermined frequency and the one or more spray droplet size statistics.