Abstract

In addition to the increase of thermal conductivity, heat transferring for nanofluids strengthening mechanism also includes the changes of the flow characteristics, therefore it is needed to take an in-depth research on nanofluids flow characteristics. However previous visualization experiment do not quantitatively analyze the change of flow characteristics after nano-particles is added, do not reveal the mechanism of nanofluids changing the characteristics of the fluid in intense turbulent flow condition. Therefore in this paper, by means of particle image velocimetry, quantitatively study SiO2-water nanofluids flow characteristics in intense turbulent flow condition and analyze the influence of SiO2-water nanofluids on turbulent flow energy by measuring the pressure drop caused by fluid flowing through the channel.

Fluid flow through rectangular convex channel (channel composed of continuous staggered rectangular convex platform) to obtain the steady intense turbulent flow. The rectangular convex channel makes the fluid flow through obstacles for several times, so that the flow direction changes for several times, and vortexes are generated in the local scope, which makes turbulence enhance and increases minor loss. In this way, flow can be in the intense turbulent state under a low flow rate, which meets the experiment requirement and is convenient to compare the influence of nano-particles on flow resistance and energy loss. The experiment takes the quantitative PIV experimental research on pure water and the volume fraction of 0.5% SiO2-water nanofluids respectively in the Reynolds number is 2300, 2500, 3000, 4000. Through the experiment, we can obtain nanofluids turbulent flow condition fluctuating velocity, turbulence kinetic, energy loss and so on, and the fluid flow velocity vector, streamline and vorticity graph. Through the quantitative comparison of the spiral numbers, the vorticity distribution, and energy loss, analyze strengthening effect and influence of flow resistance on basic fluid after adding nanoparticles.

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