ACTA AERONAUTICAET ASTRONAUTICA SINICA >
Numerical Investigation on Unsteady Flow and Heat Transfer Characteristics of Piezoelectric Fan
Received date: 2012-07-10
Revised date: 2013-01-22
Online published: 2013-01-24
Supported by
National Natural Science Foundation of China (51106073); Aeronautical Science Foundation of China(2011ZB52020)
A two-dimensional numerical investigation of the unsteady flow characteristics caused by a piezoelectric fan is performed by using a moving-grid technique in order to further address the flow and heat transfer characteristics. The results are as follows: two strong vortices with opposite rotating directions are observed at the trailing edge of the fan (counter-clockwise on the top side and clockwise on the bottom side). The vortical structures show cyclical variations over time in size, location and disturbance range. The time-averaged velocity does not decrease monotonically with the increase of the distance between the fan tip and the measured location. The maximum velocity appears at the position where the distance from the fan tip equals to the amplitude, and this position is also the location of the vortex core when the vortex reaches the maximum size. The vortices interfere and fuse with the surrounding fluid and form a jet in the process of development and movement, which produces an enhanced heat transfer effect on the heated wall. The lowest temperature as well as the peak convective heat transfer coefficient does not appear at the neutral position of the heated wall, but at the location corresponding to where the value of turbulent density is the largest.
TAN Lei , TAN Xiaoming , ZHANG Jingzhou . Numerical Investigation on Unsteady Flow and Heat Transfer Characteristics of Piezoelectric Fan[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2013 , 34(6) : 1277 -1284 . DOI: 10.7527/S1000-6893.2013.0074
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