Mixer swirling-flow

The second type of mixer uses two impinging jets exiting from two borings to contact the reactants (for more detailed information, see Section 1.3.33, Jet Collision Turbulent or Swirling-flow Mixing). 

One of the benefits of static mixers like those mentioned above are the secondary flow patterns set up by the swirling helical flow. 

The insertion of small static mixing elements (SME) is common to achieve swirls and eddies in pipe flow, albeit usually not being turbulent [71]. The flow obstacles are fairly small compared with the pipe diameter, unlike typical packings of static mixers which fully cover the diameter of the channel. Such mixing elements provide abrupt changes in surface orientation to result in flow separation and subsequent eddy production. 

M 31] [P 28] The time evolution of the flow patterns in the cross-shaped micro mixer with two static mixing elements was monitored by simulation at time intervals of 50,150, 500 ps and 1 ms after application of pressure [71]. In addition to seeing the evolution of the swirling patterns, it was concluded from this analysis that at 500 ps a nearly homogeneous distribution of the mass fractions is given and at 1 ms this is indeed completed. Hence the theoretical mixing time of the mixer may be below 1 ms. 

M 81] [P 70] A microscopy-image analysis of the color formation due to a reactive approach reveals that the micro mixer with helical elements and barriers gives a better performance than the micro mixer with helical elements but without barriers and a reference pipe structure without either helical elements or barriers (see Figure 1.167) [3], The pipe gives the expected profile with two colorless fluid compartments on top and at bottom, separated by a colored interface. This is indicative of the absence of any swirling, secondary flow. 

Turbine designs are intermediate between paddles and propellers. Turbines are effective mixers over a wide viscosity range and provide a very versatile mixing tool. The ratio of radial to tangential flow, the predominating parameters with this impeller, increases as the operating speed increases. Pitched-blade turbines are sometimes used to increase axial flow. Baffles must be used to limit swirling unless the turbine is shrouded. 

---