Attenuation of large amplitude pressure disturbances by liquid droplets

This report summarizes activities carried out to investigate flow processes which govern the attenuation of large amplitude pressure disturbances in gases containing high mass fractions of liquid droplets. A shock tube driver and steady flow test section with supporting gas and liquid supplies, control and monitoring instruments have been developed for tests. The test regime includes droplet/gas mass ratios from 0.1 to 1.0, shock pressure ratios up to 5.6, and initial gas and liquid gas and liquid temperatures from ambient to 98 C. An optical diagnostic system has been developed to determine the dynamic response of the droplet field to rapidly varying flows behind shock waves. The angular distribution of scattered light from a probe laser beam is monitored using a photodetector array and associated high frequency response dAta acquisition equipment. Data for a complete size distribution measurement is acquired and stored every 40 microsec. The scattered and attenuated light measurements using a data reduction code based on scattering theory. The pressure wave amplitude and waveform is determined as a function of location and time using high frquency response pressure transducers. The test apparatus and diagnostic system were developed to the point of checkout testing during the first year of the program. Wave attenuation and droplet dynamics testing will begin early in the second program year.