Performance of two shrouded probes for the collection of liquid aerosols in a wind tunnel optimized for high air speeds

Abstract

A combination of type A (high flow model) or B (low flow model) shrouded probe and appropriate isokinetic air-sampler (IAS) was tested in a wind tunnel that was optimized for high air speed testing using computational flow modeling. Liquid uranine aerosols (LUA) with AED (aerodynamic equivalent diameter) of 10 lm were generated at a constant flow rate using a vibrating orifice aerosol generator. The monodispersed aerosols were introduced into a wind tunnel at speeds of 5, 10, 15 and 20 m/s. The high flow (A) or low flow (B) model shrouded probe and the appropriate isokinetic air-sampler (IAS) was co-located to collect the LUA simultaneously during each treatment. After the test, the LUA deposited on the filters and inside the walls of the two air-samplers were collected and analyzed for fluorescence intensity units to determine the wall loss, transmission and aspiration ratios. While the type B shrouded probe had 20% (at 10 m/s) and 14.3% (at 15 m/s) higher wall loss ratios than model A, it had 16.1% (at 10 m/s) and 11.6% (at 15 m/s) higher transmission ratios compared to model A. Similarly, probe B had 17.6% (at 10 m/s) and 14.6% (at 15 m/s) higher aspiration ratios than probe A at similar air velocities. Overall, the wall loss, transmission and aspiration ratios of 10 mm AED ULA measured with two types of shrouded probes at 5, 10, 15 and 20 m/s air velocities in the optimized wind tunnel had good agreement with the range of standard data.