Experimental Study Of Complex Heat Tranfer Enhancement With Jet Impingement On Rough-Surface

It is all the way important for academe and engineering to the investigation and application of heat transfer enhancement. As an effective manner of enhanced heat transfer, jet impingement has the highest heat transfer coefficient. Thus it is more and more important and gets further lucubrate. The technology of jet impingement heat transfer has been broadly applied to industrial processes with high heat flux, such as microelectronics and internal-combustion engine.Rough surface could enhance the convective heat transfer. Jet impingement on rough surface will greatly increase heat transfer coefficients and promote the application of complex enhanced heat transfer with jet impingement.In this dissertation, single jet impingement heat transfer on rough surface has been investigated. The distributions of temperature are measured along impinging surface. Then, heat transfer coefficients are calculated. In order to compare with heat transfer on rough surface, similar experiments with clean surface are done to study the complex effect of jet impingement with rough surface.Firstly, an experimental system of jet impingement heat transfer was set up for experiments of jet impingement on relative clean surface with Rl 13 as medium. The experimental results are similar to that with film tester. Heat transfer coefficients at stagnation point always increase with the increasing of Reynolds number. But local heat transfer coefficients at stagnation point are smaller than that of previous research as the average heat transfer is focused in the present experiment. Secondary peaks are not found near the impinging wall with high Reynolds number. Furthermore, relative rough surface was used in experiments. Investigation of jet impingement heat transfer on rough surface was carried out with Rl 13 as medium. It is found that, jet impingement heat transfer coefficient are much greater than that with relative clean surface under the same conditions comparing. The enhancement rates of local heat transfer at stagnation point are increased with the increasing of Reynolds number. Average heat transfer coefficients are increased with the increasing of Reynolds number at the same nozzle-to-plate spacing.