Effect of Impingement

When scale drawings are made, the effectiveness of impingement baffles can be evaluated easily. Sometimes it is necessary to relocate or make slight size changes in order to properly protect the tubes and direct the vapor flow. 

Tamir [5] analyzed the effects of impinging streams enhancing physical and chemical absorption processes. To describe the enhancement of absorption, the following two enhancements were defined to account for the two factors oscillation movement and re-atomization-coalescence of droplets, respectively... 

In earlier investigations aimed mainly at verifying the enhancement effects of impinging streams, the common horizontal two impinging streams was mostly employed, although some other flow configurations were also sometimes used. 

It may be considered from the analysis described above that the contributions of the three regions to absorption are comparable. In other words, it is uncertain whether the effect of impinging streams is the lynchpin or not for carrying out absorption in such a device. 

To examine the reasonableness of the device structure, the effects of impinging distance, S, and placement of the nozzles are studied in certain ranges. 

It can be seen in Figs 7.18 and 7.19 that in range of the impinging velocity w0 from 5.53 TO 16.62 m s-1 the values for volumetric mass transfer coefficient and the gas-film one ranged from 0.577 to 1.037 s l and 0.00641 to 0.0416 m s1, respectively, showing clearly the effect of impinging streams enhancing transfer between phases. 

Effect of impingement angle on erosive wear of polyurethanes. 

A variety of techniques have been used to model the deposition processes. Frequently a small furnace will be built to provide controlled combustion and careful monitoring of the conditions. The coal is burned and the ash is allowed to impinge on tubes. The increase in deposit weight is noted as a function of time under different conditions. This approach has been helpful and is useful if variations in ash chemistry are the most significant variables. In some furnaces, the aerodynamics are also quite important and cannot usually be scaled. It is also possible to model the effects of impinging ash-like particles by substituting glasses of known fusion or viscosity properties for the coal ash type materials. 

Smitha, A.J. Stratmann, M. Hassel, A.W. Investigation of the effect of impingement angle on tribocorrosion using single impacts, Electrochim. Acta 51 (2006) 6521-6526. 

FIG. 3—Chart showing the effect of Impingement angle on erosion weight loss for metals and ceramics. Aluminum characteristics (typical for ductile metals) are shown In the dashed line. Aluminum oxide (ceramics) is represented by the solid line. The dashed line follows theory while the solid line deviation at about 40° represents practical experience (from Ref 1). 

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