Experimental And Numerical Study Of Convective Heat Transfer Of The Flow From Vibrating Tube With The Pulsating Flow

Heat transfer with pulsating flow and heat transfer with wall vibrating are two common unsteady ways to exchange heat. Much attention has been put on their heat transfer characteristics. The results show that flow pulsating and wall vibration can enhance heat transfer. But there are few literatures about heat transfer characteristics affected both by flow pulsating and by wall vibration. The problem of heat transfer characteristics of the flow past a vibrating wall with pulsating flow is experimentally and numerically investigated in this paper.On the testing system of heat transfer characteristics of the flow past a single vibrating tube with pulsating flow, the influence of the flow average velocity, the flow pulsating amplitude and frequency, the tube vibrating frequency on heat transfer is studied. The results show that the convective heat transfer coefficient increases with the flow pulsating frequency increasing, with a lower frequency, the increasing argument is bigger, the increasing argument becomes small with the frequency increasing; Strenuous press fluctuation and big pulsating amplitude apply a profound effect on convective heat transfer coefficient; when the inlet flow velocity is given, there is a optimal frequency on which convective heat transfer coefficient attains a peak value; the increasing flow velocity and the increasing vibrating frequency will lead to a increasing convective heat transfer coefficient.The numerical simulation is put on heat transfer characteristics of the flow past a single vibrating tube with pulsating flow. The numerical results show that with a rather smaller flow velocity, when the flow pulsating frequency is close to the eddy breaking off frequency, the first peak of heat transfer coefficient appears, and when the pulsating frequency equals to the vibrating frequency, the second peak of heat transfer coefficient appears, this demonstrates the effect of the breaking off eddy on heat transfer is less than that of the tube vibrating; convective heat transfer coefficient increases with the flow average velocity increasing, the effect of the breaking off eddy and the tube vibrating on heat transfer weaken; the elevated pulsating amplitude will lead to a evidently increased convective heat transfer coefficient; compared the trend of the velocity of the flow in boundary layer with trend of convective heat transfer coefficient, it is found that the variation of convective heat transfer coefficient lag that of the normal flow velocity component relative to the moving tube in boundary layer, but the tendency of theirs are basically identical, the paper consider the augment of the relative normal flow velocity component in boundary layer leads to the augment of convective heat transfer coefficient; the reason for the augment of the relative normal flow velocity component in boundary layer is the enhanced intensity of the second flow along the tube surface and the breaking off eddy; The trend of the flow turbulivity adjacent to the tube and that of convective heat transfer coefficient is basically identical, the paper think the flow turbulivity adjacent to the tube can reflect the variety of heat transfer on real time.The numerical simulation is put on heat transfer of the flow past the vibrating in-line bundles and staggered bundles with pulsating flow. The numerical results show that the effect of the breaking off eddy on heat transfer of the flow past the bundles is bigger than that. on heat transfer of the flow past the single tube; the heat transfer enhancement of flow pulsating on heat transfer of the flow past the bundles is bigger that on heat transfer of the flow past the single tube.