Abstract: A method is taught for preparing a coating hopper prior to initiation of coating a liquid coating composition at a predetermined coating flow rate onto a moving substrate wherein the coating hopper includes at least one internal flow path therethrough. The internal flow path(s) of the coating hopper are drained. The liquid coating composition is introduced into internal flow path(s) at a purge flow rate which may be determined empirically. The internal flow path(s) are filled with the liquid coating composition and with the liquid coating composition then discharging from the internal flow path(s) onto a slide surface of the coating hopper, the liquid coating composition flowing down the slide surface and over a lip of the coating hopper at the purge rate to a drain. The flow of the liquid coating composition through the internal flow path(s) is maintained at the purge rate until air within the internal flow path(s) has been displaced from the coating hopper.

Abstract: A movable trough is taught for establishing a uniform wetting line on the rear face of a curtain coating hopper lip. The trough can be pivoted or moved linearly into a position such that the hopper lip resides in or proximate to the movable trough. The curtain coating apparatus is then started and the coating solution leaving the hopper lip is intercepted by the trough. The coating solution flowing over the lip fills and floods the movable trough. The flooding of the trough forces the coating solution to substantially wet (to a height on the back side of the lip significantly higher than that of natural product flow) the back side of the hopper lip. The movable trough is then retracted from its position immediately beneath the hopper lip and intercepting the coating solution exiting the hopper lip to thereby allow the free-falling curtain to form and begin impingement on the moving support web to be coated.

Abstract: A method for hydrodynamic cleaning of a piping system using two-phase flow. A model for predicting peak wall shear stress for two-phase flow is used to determine an optimum flow rate ratio which achieves a maximum wall shear stress in the particular piping system to be cleaned. The optimum flow rate is first established by turning on the liquid and gas flows through the piping system to be cleaned and allowing the flow to reach steady state conditions. The back pressure of the system is measured and the optimization model is used to determine the optimum flow rate ratio. Once the optimum flow rate ratio has been calculated, the liquid flow rate and the gas flow rates can be adjusted such that the optimum ratio is achieved. The two-phase back pressure is then measured to verify that the optimum flow rate ratio has been used. This is done by comparing the measured optimum two-phase flow back pressure with the initial two-phase back pressure used in the equations.

Abstract: A method and apparatus for measuring wall shear stress in pipe as a result of fluid flow therethrough employs a glass flow tube, magnetic particles of sufficiently small size such that the form drag force on the individual particles is orders of magnitude smaller than the viscous shear forces on the particle, and a magnet of known magnetic field strength. The glass flow tube with a known coefficient of friction allows visual inspection of particle release and further allows for the determination of the frictional forces on the particles. The magnetic particles are placed inside the tube with the magnet held in close proximity to the exterior wall of the tube. With the particles in place, fluid flow is initiated. The magnetic field strength at the surface of the flow tube is then reduced until the magnetic particles are hydrodynamically dislodged from the interior of the glass tube.

Abstract: A liquid flow distribution apparatus for forming highly uniform liquid layers on substrates without stagnation within a flow distribution cavity of the apparatus. A primary cavity has a primary inlet means and a plurality of secondary inlet conduits which terminate in angled secondary ports in the cavity wall. Each of the secondary ports is angled away from the primary inlet means. The apparatus can be used under varying rheological conditions.