Studies on Magnifying and Improvement of the Perforated Dust Head for the Pipe Duster (III)

Aerial Flowing and Discharging Mechgnism

Abstract

1) The mean air velocity V and the penetrating flow rate at a section of a p. d. head (an abridgement of perforated dust head) were calculated by multiplying the pipe factor (Φ=V/V_c) to the central penetrating velocity V_c, because it was good enough for such quite a small section. This method of calculation made it neccessary to measure the pipe factor of the p. d. head.
The maximum velocity at a section was biased from the central axis toward the perforated bottom wall. The pipe factor Φ was affected by the opening ratio R₀ of the wall as shown in Fig. 5 and was expressed by equ, (13) practically, Besides, Reynolds' number did not always affect the pipe factor Φ.
2) From the fact that the decreased amount of penetrating flow rate between upper lower sections is equal to the total discharge rate from outlets in a given division, the fluidal mechanism of the branching discharge and the coefficient of discharge C_d were elucidated experimentally, and were shown in Fig. 2-3 and expression (8) or (10).
The actual discharged air stream originated at the depth of nearly 4.5mm=η from the front edge of each outlet in every head. (Table 1-2)
The discharged quantity qi from a given outlet was expressed by the next formula,
qi=C_dγ₀/γ_aυaicosθ√1+(V_η/υ)²
or
qi=C_d(V_ηsinθ+γ₀/γ_aυcosθ)aicosθ
where, V_η= penetrating velocity at the η=4.5mm depth, υ= assumed divergent velocity calculated with the static pressure. The sectional area of a discharging stream should be made equal to the projected area of the outlet toward the discharging direction.
The discharging inclination θ and the coefficient of discharge C_d were expressed as functions of Φ_η (the rate of co-perpendicular streams V_η vs. υ).