Airborne Interferometric Cloud Particle Imager: Instrumentation and Applications to Icing Wind Tunnel

An instrument for characterizing icing cloud particles in wind tunnels is critically required to enhance the understanding of aircraft icing mechanisms. Moreover, measuring multiscale and multiphase icing cloud particles presents significant challenges, particularly under extreme environmental conditions. This work elucidates the development and validation of the Airborne Interferometric Cloud Particle Imager (AICPI). AICPI’s optical-mechanical-electronic-thermal integrated design guarantees dependable operation in icing wind tunnels. Validation experiments, conducted using a monodisperse droplet generator and a high-speed microscopic imaging system, confirmed that AICPI achieves a relative size measurement error of less than 5%. AICPI was deployed in one ambient temperature wind tunnel and two industrial icing wind tunnels with test section dimensions ranging from 0.6 m × 0.6 m to 3.0 m × 2.0 m, wind speeds up to 50 m/s and temperatures as low as -14◦C. In practical applications, AICPI detects particle sizes within the operational range of 10-200 μm. Results from wind tunnel tests demonstrate AICPI’s feasibility for particle size measurement and phase discrimination in mixed-phase cloud fields.