| Elliptical cylinder is more and more widely used as the original part of special-shaped heat transfer,which indicates that the study of flow and heat transfer around elliptical cylinder needs to be more in-depth.The shape evolution of elliptical cylinder is more flexible,and the flow and heat transfer characteristics of elliptical cylinder with different axial length ratio are quite different.In the application of heat exchanger,it is necessary to clarify the influence of elliptical cylinder shape on flow and heat transfer characteristics.In this paper,the flow and heat transfer characteristics of elliptical cylinders with axle length ratio of 0.1 to 1 in the range of Reynolds number 4000 to 60000 are studied experimentally.The instantaneous velocity field distribution of the wake around an elliptical cylinder is obtained by PIV particle imaging technique.The time-averaged velocity distribution and the separation point of the boundary layer are analyzed.The generation,development,shedding process of the wake vortices and the relationship between the characteristic parameters of the vortices and the axial length ratio are studied.Based on the principle of heat-mass analogy,the naphthalene sublimation heat transfer simulation experiment was carried out in a wind tunnel.The local heat transfer characteristics of the elliptical cylinder surface were studied by replacing the local heat transfer with the small area average heat transfer,and the influence of the angle of attack on the average convective heat transfer characteristics of the elliptical cylinder surface was studied.In this paper,by studying the flow and heat transfer characteristics of elliptical cylinder,the experimental correlations of mean convective heat transfer coefficient anddrag coefficient with Reynolds number for elliptical cylinder with different axial length ratios are summarized,which provide basic data for further study and engineering application of flow and heat transfer characteristics of elliptical cylinder. |
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