Holographic diagnostics of breakup phenomena of impinging jets for liquid rocket motor applications

The use of pulsed laser holography in analyzing the atomization of impinging jets is evaluated using a holographic camera system capable of recording a 3-D image of the atomization process in 3×10⁻⁸ seconds. The holocamera and the experimental configuration and procedure are described in detail. Two nozzles were fabricated to produce 1 mm diameter liquid water jets that impinged at 60 and 90 degrees. Holograms were obtained for each nozzle at liquid velocities of 20 and 40 m/s. Analysis of the holograms revealed the evolution of the jets from the plane of emergence through the region of droplet formation. Features of interest included the growth of disturbances prior to the breakup region and the effect of these disturbances on the formation of ligaments and liquid globules. Periodic disturbances both in the jets and after the breakup region were identified which may have an effect on the delivery of fuel to the combustion zone. Preliminary analyses show that waves of atomized liquid formed after impingement are closely correlated to waves measured on the jets, leading to the possibility of controlling the atomization process at the nozzle.