![]() From Equation 1 above, the gap opening helps determine the hydraulic diameter, Dh. The gap opening is typically 0.5″ (13mm). A blower does not generate a high force, so the opening of the blower-type air knife has to be larger to overcome any back pressure the opening creates. It uses the force of the compressed air to “push” it through the small opening to create a strong velocity. ![]() The Super Air Knife has a gap opening of 0.002″ (0.05mm). The main difference between the two products is the dimension of the slot opening. The EXAIR Super Air Knife is powered by compressed air, and the blower-type air knife is powered by an air blower. Both products are designed to clean and blow off wide areas like conveyor belts. Let’s do a comparison of Reynolds numbers between the EXAIR Super Air Knife and a blower-type air knife. ![]() When it comes to effective blowing, cleaning and lower noise levels, laminar flow is optimal. The area between these two numbers is the transitional area where you start to get small eddy currents and velocities in a non-linear direction. If Re is greater than 4000, then it is considered turbulent (chaotic and disarrayed). If the Reynolds number, Re, is below 2300, then it is considered laminar (streamline and predictable). The value of Re will determine the state in which the fluid (liquid or gas) will move. U – Kinematic Viscosity (Feet^2/sec or Meter^2/sec) The formula to determine the Reynolds number is as follows: If the inertial forces are dominant over the viscous forces, the fluid will act in a violent and chaotic manner. This number is the ratio of the inertial forces to the viscous forces. What is laminar flow and turbulent flow? Osborne Reynolds popularized this phenomenon with a dimensionless number, Re.
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