An experimental setup to determine the particle size distribution (PSD) of a pressurized oil aerosol (p < 10 barÞ was validated. The combination of optical particle counter (OPC) and scanning mobility particle sizer (SMPS) measurements allowed for the evaluation of PSDs in the size range 40 nm < d p < 3 lm. The raw gas oil emissions of two oil injected screw compressors were determined and compared to a test aerosol generated by a Laskin Nozzle aerosol generator. While the screw compressors showed considerable differences in gravimetric oil load, the normalized PSDs of both compressors were found to be similar, exhibiting main mass fractions in the particle size range between 0.1 and 2 mm. The influence of operating conditions on the fractional separation efficiency of fibrous oil mist filters was also studied in this work using a conventional air/oil separator filter. An increase of either pressure, temperature, filter face velocity or oil loading rate led to a deterioration of separation efficiency emphasizing the need for filter testing under realistic operating conditions.

The chromatic confocal measurement technique is used to investigate the dynamics of radially expanding free liquid sheets generated by liquid jet impingement onto the flat end of a harmonically excited cylinder. Measurements of the sinuous-mode capillary waves are compared to experimental results reported by Bremond et al. (2007) and analytical solutions from two inviscid linear theories: The "aerodynamic (wave-growth)" theory by Bremond et al. (2007), which considers the interaction between the liquid film and the surrounding gas phase, and the linear theory by Tirumkudulu and Paramati (2013) which neglects the gas phase surrounding the liquid sheet but predicts growth of forced sinuous disturbances due to higher-order inertia terms associated with the thinning of the radially expanding sheet (“thinning” theory). For liquid Weber numbers Wed based on impinging jet velocity and jet diameter which are larger than 800 and aerodynamically stable forcing conditions, agreement with "thinning" theory is found in terms of radial positions of nodes and anti-nodes of the sheet disturbance envelope as well as growth of envelope maxima and minima. However, absolute amplitude values are significantly overpredicted in this case. For all other investigated operating conditions where instability due to film thinning is expected to dominate film dynamics (according to "thinning theory"), no such instability was observed experimentally. For most investigated cases, "aerodynamic wave-growth" theory agreed better with the experimentally observed film behavior. The importance of the naturally most-amplified aerodynamic mode was considered but could not be quantified as part of the present investigation.