Alkali Dosing Profiles and Mass Transfer in Jet Dyeing
Controlled progressive alkali dosing matches jet fabric loop velocity to eliminate surface fixation spikes and secure level shade fixation on cellulosic cloth.
Venturi Nozzle Velocity
Fluid Acceleration
Kinetic energy measurements of a liquid or gas as it passes through a constricted section of a pipe define the transport capacity of a dyeing machine. Venturi nozzle velocity determines the speed at which the fabric rope moves through the jet, influencing the number of times the material contacts the dye liquor. High speeds are necessary to prevent creasing and to ensure that the chemical treatment is applied uniformly across the entire length of the piece.
Pressure Differential
Physical laws dictating that fluid speed must increase as the area of flow decreases drive the mechanism. By narrowing the passage, the venturi nozzle velocity increases while the static pressure drops, creating a suction effect that helps to open the fabric folds. This opening action is essential for avoiding dye streaks and ensuring that the finish penetrates the interior of the yarn bundle.
Mechanical Stress
Managing the force exerted on the textile prevents physical damage to delicate fibres. If the venturi nozzle velocity is set too high for a lightweight knit, the resulting turbulence can cause surface fuzzing or structural distortion. Engineers calibrate the pump pressure to balance the need for rapid liquor exchange with the preservation of the fabric’s physical integrity and hand-feel.
Operational Efficiency
Optimisation of these flow rates reduces the total time required for the dyeing cycle and lowers the consumption of energy per kilogram of processed goods.