Flow Characteristic of Hydraulic Headbox Based on Complementary Pulp Distribution

ABSTRACT

In order to study the effect of complementary pulp distribution, computational fluid dynamic (CFD) was used to research on flow characteristic of hydraulic headbox based on complementary pulp distribution. Mass flow rate out of mixing chamber and velocity distribution at slice of headbox were experimented. The results show that because of simplified design, there was a little gradient of velocity and pressure which caused non uniform distribution of mass flow rate out of branch pipes. Distribution of mass flow rate was ascended from inlet of header to outlet and the deviation was - 2.33% and 1.82%. There was intense interference between the jets of branch pipes in mixing chamber and the jets could be sufficiently and complementarily mixed in rows and ranks. But the interference in the jets caused the accumulation of the jets in the central section of mixing chamber and mass flow rate out of mixing chamber in the center was higher than the two sides, and the maximum deviation was 0.538%. Distribution of velocity of pulp stock at slice of headbox was very gentle and curve of distribution presented only slight fluctuation. The maximum deviation of velocity was only 0.175%. From the results of the experiment, the test values of mass flow rate out of mixing chamber were inosculated with the calculated values and tested values of velocity at the slice of headbox were in accordance with the calculated values. The results of experiment explained that the method of complementary pulp distribution was reasonable and could obviously improve performance of pulp distribution of hydraulic headbox.

Keywords:

Complementary pulp distribution, computational fluid dynamic, flow, hydraulic headbox, numerical simulation.