Geometry rotor-stator

In high force dispersion devices, ultrasonication is used today especially for the homogenization of small quantities, whereas rotor-stator dispersers with special rotor geometries, microfluidizers, or high-pressure homogenizers are best for the emulsification of larger quantities. 

As a result from computational model 1 a hybrid grid for a laboratory size OK flotation cell with unstructured cells in the rotor domain and structured cells in the stator and tank domain was generated. The tank was a cylindrical, unbaffled tank with Outokumpu s rotor-stator mixing device. Computational geometry is shown in figure 8. Geometrical details of the tank are given in table 2. 

In Fig. 4.33 a refiner with cylindrical rotor/stator geometry is shown. The stock enters the center of the machine via the hollow center shaft and is refined during its helical horizontal path to the two stock outlet pipes. The refining energy is controlled by the gap between the rotor and the stator which is adjusted by cone-shaped means. 

Fig. 4.33 Refiner with cylindrical rotor/stator geometry (source Andrltz).

Figure 8-1 Couette rotor-stator geometry, single-stage design (a) simple Couette (b) toothed rotor-stator (c) schematic representation of hydrodynamics (d) commercial...

Chemineer Greerco offers a different rotor-stator geometry. In this case, as shown in Figure S-4a and b, the rotor is an axial impeller that pushes the fluid axially through holes bored into the stator. The rotating action of the impeller, however, creates some tangential shear flow inside the stator. There is a two-stage version called the tandem shear pipeline mixer. This consists of a primary disperser... 

Figure 8-7 Rotor-stator head geometry for the Silverson L4R batch rotor-stator mixer (a) side view (b) bottom view showing rotor (c) range of stator geometries.

Thus from Equation 2-215 we see that for a given dynamo geometry, the developed torque only depends on the interaction between two magnetic fields and their orientation with respect to each other. One or both of the magnetic fields may be induced by a current. If one of the fields is the field of a magnet, then it may be either in the rotor or the stator. If the rotation results from the imposition of mechanical power on the rotor, the device is called a generator. If the rotation is caused by the flow of current, the device is called a motor, i.e., converts electric power to mechanical power. 

Figure 4-193 is the side view of a single-turbine stage and describes the geometry of the rotor and stator. 

Figure 4-193. Turbine rotor and stator geometry of a single stage. (Courtesy Smith International, Inc.)...

Figure 6-4. Rotation plastimeter geometry, (a), (b) and (c) Coaxial cylinder types (d) and (e) concentric disc types ((d) is the Mooney geometry). A is usually the stator and B the rotor, C is the rotating shaft and r is the cylinder radius (much larger than the clearance between A and B). xy indicates the mid-plane along which the chamber can be opened for filling.

The drive system of a rotational rheometer is likely to be optimized in one of two ways depending upon its preferred mode of operation. The most common form of rheometer is a controlled-rate (controlled-speed) device. This configuration is also used in most viscometers and has been around for decades. A shear rate is applied to a rotor by the motor controlling the viscometer s speed. The rotor is normally a flat plate or cylindrical cup. The stator is thus a cone or plate for the first two geometries or a cylindrical bob for the third (Figure HI. 1.1). The stator is linked to the rotor via the sample, which acts to couple the input signal like an automobile transmission. Thus, the torque on the stator when measured by a transducer is used to derive the shear stress in the sample. 

Rotational rheometer n. An instrument for measuring the viscosity of molten polymers (any many other fluid types) in which the sample is held at a controlled temperature between a stator and a rotor. From the torque on either element and the relative rotational speed, the viscosity can be inferred. The most satisfactory type for melts is the cone-and-plate geometry, in which the vertex of the cone almost touches the plate and the specimen is situated between the two elements. This provides a uniform shear rate throughout the specimen. It may be operated in steady rotation or in an oscillatory mode. 

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