JP Journal of Heat and Mass Transfer
Volume 18, Issue 2, Pages 405 - 422
(December 2019) http://dx.doi.org/10.17654/HM018020405 |
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NUMERICAL STUDY ON CHOKING PHENOMENON IN MICRO TUBE
Vignesh Ram Petha Sethuraman and Heuy Dong Kim
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Abstract: Numerical simulations of an axially symmetric micro tube have been carried out to understand the characteristic of flow field in the vicinity of the exit. The heat transfer characteristics and choking of micro sized tube have a wide variety of applications, such as flow meter, pneumatic systems and so on. The flow Mach number exceeds unity for the choked flow at the exit of the tube. This contradicts the one-dimensional flow theory. To investigate this flow field mechanism inside the micro tube in detail, an extensive numerical simulation is carried out. Also, the effect of different wall thermal boundary condition on choking phenomenon is studied. The results obtained from the present numerical simulation show that thinning of the boundary layer is produced due to the proximal tube exit, with subsonic inlet conditions for both the hot wall and cold wall cases. Also, three dimensional flow fields at the exit of the micro tube indicate that the upstream flow field is influenced by the vorticity formed in the azimuthal direction. This disturbance causes the active flow passage to behave like a nozzle causing the increase in exit Mach number. |
Keywords and phrases: micro flows, choking, boundary layer thinning, MEMS.
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