Objective The structure of the measuring cavity for the aerosol monitor were optimized to enhance the ability of the structure of the measuring cavity to constrain the sample flow, in order to improve the detection accuracy of the aerosol monitor. Methods According to the structure features of the aerosol monitor, we designed several sets of parameters for different parts: the shapes of the nozzle (round and flat) , the length of the export needle (22 mm, 34 mm) and the export flow (1 L/min, 2 L/min, 2. 83 L/min, 5 L/min, 10 L/min) .We also used the sheath gas to focus the sample flow, which imitated the three-dimensional hydrodynamic focusing of the flow cytometry technology. We designed several kinds of velocity of sample flow and sheath flow (vsa= 9 m/s, vsh= 3 m/s; vsa= 9 m/s, vsh= 4. 5 m/s; vsa= 9 m/s, vsh= 1. 4 m/s; vsa= 9 m/s, vsh= 0) . We used the Solid Works software to design the measuring cavity and used the ICEM and Fluent software to simulate the distribution of the sample flow and the sheath flow. Results The constraint ability of the measuring cavity was the best under this condition: vsa= 9 m/s, vsh= 1. 4 m/s, using round nozzle, long export needle and the export flow was 2. 83 L/min. Conclusions The sheath gas structure, the nozzle shape, the length of the export needle and the export flow affect the detection accuracy of the aerosol monitor, and the ability of constraining the sample flow can be enhanced by improving the structure of the measuring cavity.
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