Bubbly drag reduction in a vertical Couette–Taylor system with superimposed axial flow
| Autor: | Reza Maryami, M Javad poor, Said Farahat, M H Shafiei Mayam |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Fluid Dynamics Research. 46:055504 |
| ISSN: | 1873-7005 0169-5983 |
| DOI: | 10.1088/0169-5983/46/5/055504 |
| Popis: | The effect of axial flow on bubbly drag reduction has been experimentally investigated in a vertical Couette–Taylor flow system. The water flow is combined from circumferential and axial flow. Flow condition is fully turbulence and Taylor vortices have appeared in the annulus gap. The shear stress modification in the simultaneous presence of air bubbles and axial flow in the system has been studied by measuring torque acting on the inner cylinder. The results show that axial flow improves the effect of bubbles on drag reduction by damping Taylor vortices and increasing upward velocity of bubbles. In this case, drag reduction of more than 25% has been achieved, which corresponds to lower tested and this amount is gradually decreased with increasing in each and . Increasing causes drag reduction enhancement which could be due to the effect of bubbles on flow density reduction, flow fluctuations and Taylor vortices. Moreover, it is observed that skin friction is affected by axial flow solely and by increasing its volume rates, drag reduction reaches 11%. It is concluded that when bubbles and axial flow are simultaneously applied into the Couette–Taylor flow, the amount of achieved drag reduction is more than when they are separately applied. |
| Databáze: | OpenAIRE |
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