Dynamic Range Limitations in Phase Doppler Interferometry Measurements
J F. Widmann, Cary Presser, Stefan D. Leigh
It has been well established that the dynamic range of phase Doppler interferometry (PDI) size measurements is limited by the photomultiplier tubes (PMT). A statistical method is presented to overcome this limitation by combining data sets collected over different size ranges (PMT gains). The method is discussed and validated using a simulation in which droplets are sampled from monomodal and multimodal size distributions. The technique is also applied to experimental data collected in a reacting methanol spray. Experimental measurements of monodisperse droplets and polydisperse particles are presented showing that PMT saturation does not preclude accurate size measurements when using modern frequency domain signal processors that operate with one-bit anolog-to-digital conversion. The results presented question the accepted dynamic range limitation of PDI systems, as well as the methods of optimizing the PMT gain reported in the literature.
Atomization and Sprays
droplets, drops, dynamic range limitations, phase Doppler, sprays