Regulation-controlling of boundary layer by multi-wire-to-cylinder negative corona discharge

Multi-wire-to-cylinder corona discharge was studied for better understanding of the electrohydrodynamic phenomena which directly relate to the performance of heat transfer enhancement. A unipolar approximation model was established and numerical simulations were conducted to determinate the heat transfer and velocity distribution of ionic wind. The numerical and experiments results show good agreement. It indicates that higher applied voltage and more corona wires can help decreasing thermal boundary layer thickness and increasing velocity gradient of boundary layer, resulting in the enhancement of heat transfer. When the applied voltage increases from −7 kV to −11 kV and the number of wire increases from corona wire number 1-3, there will be a 39.8% decrease of the thickness of thermal boundary layer. In the condition of U = −11 kV, the maximum local forced convection heat transfer coefficient for corona wire number N = 3 is 12 times and the average value is 8 times higher than that of natural convection.