Numerical study of hydraulic headbox stilling chamber

Headbox is a critical part of paper machine.The formation property of paper is greatly influenced by headbox performance.In hydraulic headbox,a stilling chamber is used as a rectifier of pulp flow.Submerged jet in stilling chamber renders pulp flow an even velocity profile.The length of stilling chamber is a key parameter.Based on the realizable k-e turbulent model,the flow field of stilling chamber in hydraulic headbox was numerically simulated with software Fluent.The results of numerical simulation were verified by PIV,and the measurement results agreed well with the numerical results.Statistical theory was used to calculate the standard deviation of flow velocity on the cross sections of stilling chamber.The value of standard deviation was used to evaluate the uniformity of flow velocity.The length of stilling chamber(L)was calculated at different values of manifold tube diameter(d)and inlet velocity(v).The results showed that L increased linearly with increasing d and v.Binary function was used to fit the relationship between L and d,v.The function could be used as a reference for designing stilling chamber of hydraulic headbox.