Angle of impingement

The constant, K, depends on the target material, particle abrasiveness, and size distribution of the particles. The kinetic energy of the particles is Mp x Vp + 2. This parameter includes the solids loading, or concentration, and velocity of the particle. Alpha is the angle of impingement of the particle on the blade surface. 

Erosion. The abrasive is likely to be gas borne (as in catalytic cracking units), liquid borne (as in abrasive slurries), or gravity pulled (as in catalyst transfer lines). Because of the association of velocity and kinetic energy, the severity of erosion may increase as some power (usually up to the 3d) of the velocity. The angle of impingement also influences severity. At supersonic speeds, even water droplets can be seriously erosive. There is some evidence that the response of resisting metals is influenced by whether they are ductile or brittle. Probably most abrasion involved with hydrocarbon processing is of the erosive type. 

When there is impinging erosive wear, MDI-based polyethers are normally classified as the most suited because hydrolysis resistance is also taken into account. Certain of the more sophisticated esters have better erosive wear than the high-cost ethers (PTMEG) under hydrolysis conditions. The temperature limitation, however, is still just below that of the ether-based materials. The angle of impingement also must be taken into account. 

Catalyst concentration, velocity of the flowing stream, and angle of impingement are important factors influencing the rate of erosion. Wear increases rapidly when velocities exceed 5 to 7 ft./second with dense-phase catalyst or about 120 ft./second with lightly loaded gases (97). The... 

In the headbox nozzle, the suspension is accelerated to approximately machine speed. The thickness of the jet and, therefore, the amount of suspension is usually adjusted by swinging the upper wall of the nozzle. The shce at the nozzle outlet is often limited by a bar, which can be adjusted to an accuracy of ca. 1/1000 mm by means of spindles. This bar can be adjusted locally across the width this has been used or is still used in older headboxes to compensate for deviations in the cross machine weight profile of the web. The direction of the jet in the machine direction can be influenced by horizontally shifting the upper wall of the nozzle. In this way, the point and angle of impingement of the jet on the wire can be adjusted (Fig. 6.30). 

Angle-of-incidence (film formation) The angle of impingement of the depositing adatom flux as measured from the normal to the surface. 

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