Investigation of the characteristics of turbulent flow and heat transfer induced by a vibrating piezoelectric fan on asymmetrical concave surfaces

Abstract

This paper aims at performing an investigation numerically on the turbulent flow and thermal performances for an asymmetrical concave surface integrated with a slim vibrating piezoelectric fan. The dynamic mesh technique using a user defined function to describe the displacement function of vibrating cantilever beam is employed to model the deformation of the slim piezoelectric fan in time. Meanwhile, the SST k-ω turbulence model is chosen to capture the turbulence behavior of the flow and heat transfer. Two important factors, the relative curvature of the both sides of semicircular surfaces ( RK) and the dimensionless distance of fan offset along y-axis (Δ y/ APP) are taken into considerations during the simulation process. A considerable increase of local time-average heat transfer coefficients is observed in the vicinity of vibration envelope. The results show that the relative curvature ( RK) has a strong influence on the flow and heat transfer at both ends of the asymmetrical concave surface when its value is larger than 2. And by adjusting the dimensionless offset distance of the piezoelectric fan (Δ y/ APP), the area-averaged convective heat transfer coefficient can be increased by 20% on a small zone surrounding the fan with WPF × App (S1). The conclusions of this paper implement a theoretical attempt for expanding the application scenarios of piezoelectric fan.

Experimental and numerical investigations on the thermal performance over corrugated surfaces with different wave shapes induced by piezoelectric fan

“…As shown in Figure 2, the experimental setup used to quantitatively analyze the heat transfer performance of the corrugated surface enhanced by the piezoelectric fan is similar to that in Ref. 30. The experimental facility included three major sections: the piezoelectric fan actuation system, the test section, and the temperature acquisition system.…”

“…The simulation is performed by using Ansys Fluent 14.5. According to the previous studies, 30,34 the three-dimensional unsteady Reynolds-averaged Navier-Stokes (RANS) and the SST k - ω two-equation model are employed for modeling the turbulence viscosity. Especially need to point out, a user-defined function 30 is employed to describe the motion of the vibrating piezoelectric fan.…”