抄録
The deposition of aerosol particles and pressure loss in a coiled tube has been studied assuming it to be a bent tube which is used in various industrial fields.
Theoretical expressions for particle deposition velocity have been obtained by taking account of turbulent diffusion, gravitational and centrifugal settling, simultaneously. The deposition velocity decreases with air velocity in the laminar flow region. It has a minimum in the transient region between the laminar and turbulent flow regions. In the turbulent region, it increases sharply because of the strong centrifugal force effect, but the effect of turbulent diffusion depends upon the combination of tube diameter and coil diameter of tube, i. e., turbulent diffusion acts positively for larger Dc/D but negatively for smaller Dc/D. It agreed fairly well with experimental deposition velocity.
Pressure loss of a coiled tube with Dc/D ranging from 6.9 to 80 is measured. As a result, it is found that the smaller is Dc/D, the larger the friction factor is, and the larger the transient Reynolds number from laminar to turbulent flow region is, the smaller is Dc/D because of the strong centrifugal effect. Then, based on the experimental results, approximate expressions for that have been obtained and shown to be valid for the laminar and turbulent flow regions, respectively.
