Passivity fluid velocity effects

The present LMFBR-related thermal-hydraulics research programme consists of experimental and analytical investigations of the effects of stratification and thermal conductivity on the interaction (mixing) between two horizontal fluid layers of different velocities and temperatures. This subject has been chosen because of its suitability with respect to available experimental fadlities and expertise, its fundamental character and its relevance to passive decay-heat removal in pool-type LMFBRs. 

It can be seen that the cross channel velocity at y = 2H/3 is zero. Thus, the material in the top one-third of the channel moves towards the active flight flank and the material in the bottom two-thirds of the channel moves towards the passive flight flank. It is clear that in reality the situation becomes more complex at the flight flanks because normal velocity components must exist to achieve the circulatory flow patterns in the cross-channel direction. However, these normal velocity components will be neglected in this analysis. Normal velocity components were analyzed by Perwadtshuk and Jankow [129] and several other workers. The actual motion of the fluid is the combined effect of the cross- and down-channel velocity profiles. This is shown in Fig. 7.57. 

Changing the character of the environment, if possible, may also significantly influence corrosion. Lowering the fluid temperature and/or velocity usually produces a reduction in the rate at which corrosion occurs. Many times increasing or decreasing the concentration of some species in the solution will have a positive effect for example, the metal may experience passivation. 

---