Abstract
As a consequence of rapid development of additive manufacturing (3D printing) methods, the academic/industrial demand has been continuously increasing. One field of application is the manufacturing of heat exchanging devices using this promising method. In this regard, understanding the underlying mechanisms from a thermo-hydraulic viewpoint becomes important. Therefore, in this study, scale-resolving large eddy simulation (LES) is applied to reveal the flow details in combination with a model of roughness topology occurring in additive manufacturing. To process the transient LES results, proper orthogonal decomposition (POD) is used to extract the coherent flow structures, and the extended POD is used to rank the flow modes based on thermal importance. The main aim of the present work is to go beyond the conventionally applied methodologies used for the evaluation of surface roughness, i.e., averaged numerical study or experimental overall performance evaluation of the flow/thermal response of additively manufactured surfaces in heat exchangers. This is necessary to reveal the underlying flow mechanisms hidden in the conventional studies. In this study, the behavior of the flow over the micro-scale surface roughness model and its effects on heat transfer are studied by assuming cone-shaped roughness elements with regular placement as the dominant surface roughness structures. The major discussions reveal the footprint of flow mechanisms on the heat transfer coefficient spatial modes on the rough surface. Moreover, comparative study on the flow/thermal behavior at different levels of roughness heights shows the key role of the height-to-base-diameter ratio of the roughness elements in thermal performance.
Highlights
The trending additive manufacturing 3D printing method has been recognized as a solution to manufacture light-weight/compact heat exchanging devices with minimized material waste and facilitation of freedom in designing complex elements
Selective laser melting, electron beam melting, and direct metal laser sintering are the additive manufacturing methods dealing with metals [3,4]
The modes corresponding to the high level of roughness indicate that flow to the high level of roughness indicate that among among the low-order energetic flow modes, modes, 4.1
Summary
The trending additive manufacturing 3D printing method has been recognized as a solution to manufacture light-weight/compact heat exchanging devices with minimized material waste and facilitation of freedom in designing complex elements. The technology applies the additive shaping principle. The three-dimensional body is made by successive addition of material [1]. The term ‘additive’ opposes the conventional ‘subtractive’ manufacturing methods, where selective removal of material is used to build the specific shape of bodies. Selective laser melting (very similar to selective laser sintering and differing primarily in the materials they use), electron beam melting, and direct metal laser sintering are the additive manufacturing methods dealing with metals [3,4]
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