Micro-PIV Study Of Flow In Micro-column Channels With Different Arrangements

With the development of electronic devices towards high power and high integration,the heat generated per unit time and space increases sharply,which greatly Reduces the safety and service life of electronic devices.The heat dissipation of high power density electronic equipment has become a Research hotspot at home and abroad.Based on the principle of high surface to volume ratio and enhanced fluid disturbance,the micro column group channel heat exchanger can significantly improve the heat transfer effect,which is a potential high heat flux heat transfer method in dimensional space.Micro cylinder group structure is an important factor affecting the flow and heat transfer in micro space.Therefore,it is important to study the flow and heat transfer characteristics of micro cylinder group with different structures for efficient heat transfer in micro space.In this paper,PDMS circular cross-section in-line and staggered microcolumn group channels were designed and fabricated,and a microchannel flow visualization experimental platform was built.Using deionized water as working fluid,polystyrene particles as tracer particles,the single-phase flow in in-line and staggered microcolumn group channels was studied by micro PIV Experimental System at the volume flow rate of 1.69 ～ 67.87 ml / min.The flow mechanism of micro cylinder is Revealed.In this paper,the changes of streamline,vorticity and downstream velocity field around the micro cylinder group at different Reynolds numbers are studied by taking the micro cylinder group in the middle and tail of the channel as the Research object.The Results show that with the increase of Reynolds number,flow separation,symmetrical twin vortices and vortex shedding appear in the wake behind the cylinder.The vortex shedding and the twin vortex structure of the micro column group lag behind the Reynolds number corresponding to the conventional size.The phenomenon of in-line microcolumn group is earlier than that of staggered microcolumn group.The vortex shedding occurs in the middle of the micro column group prior to the tail;There are two vortex bands with the same strength and opposite direction on the shoulder of the micro column,and they continue to extend downstream.When the Reynolds number Reaches a certain value,the vortices on both sides of the front row of micro columns extend to the back row of micro columns.The vorticity field of the front micro column is enhanced by the Rear micro column.At the same Reynolds number,the maximum vorticity around the micro column at the same position: the cross micro column group is larger than the parallel micro column group;It is found that the transverse velocity component behind the parallel micro column group presents a "U" shape distribution,the maximum velocity appears at the center line of the gap between two adjacent micro columns,the transverse velocity distribution of the cross micro column group presents an approximate "M" shape,and the maximum velocity appears at both sides of the center line of the gap between two adjacent micro columns.The Results show that when the diameter of the micro cylinder group is one time that of the side wall,the vortex of the micro cylinder group near the wall inclines,which shows that the vortex of the micro cylinder group near the wall inclines to the side wall with more rows of near wall measuring columns,and the vortex of the micro cylinder group near the wall inclines away from the side wall with less rows of near wall measuring columns;There is no inclination of the vortex behind the micro column near the wall.In this paper,the flow characteristics of in-line and staggered micro cylinder group channels are studied by experimental means,and the comparison is made in streamline,vorticity,velocity distribution,wall effect and so on.The Results show that the flow ability of fluid in in-line micro cylinder group is stronger.The distribution of fluid velocity is more uniform in the staggered micro column group.It provides a Reliable basis for the design optimization of microchannel heat exchanger.