Modeling of flow separation of assist gas as applied to laser cutting of thick sheet metal
Modeling of flow separation of assist gas as applied to laser cutting of thick sheet metal
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DOI：
10.1016/j.apm.2008.12.011
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发表时间：
2009-09-01
影响因子：
5
通讯作者：
Zaitsev, A. V.
中科院分区：
文献类型：
--
作者：
Kovalev, O. B.;Yudin, P. V.;Zaitsev, A. V.
本文介绍了通过数值求解三维全N-S方程得到的粘性可压缩气体超音速流动的数学模拟结果，以及几何形状与激光切割相似的通道中气体射流流动的可视化实验结果。数值模拟了切割面气流的分离，并在模型装置上进行了实验验证。描述了在音速(锥形)或超音速喷管后的狭窄通道中产生的气流结构。分析了窄流道光滑表面上流动分离的特点，并提出了控制分离的机理。流动分离直接影响条纹形状和结构的变化，是激光切割表面质量差的主要原因之一。结果表明，切割板材厚度方向上条纹结构的变化与切割通道内辅助气体射流的气动特性密切相关。(C)2008 Elsevier Inc.保留所有权利。
The present paper describes the results of mathematical modeling of supersonic flows of a viscous compressible gas, obtained by numerically solving three-dimensional full Navier-Stokes equations, and also the results of experiments with visualization of gas jet flows in channels geometrically similar to the laser cut. Separation of the gas flow from the cut front is predicted numerically and then validated by experiments on a model setup. The gas flow structure arising in a narrow channel behind a sonic (conical) or supersonic nozzle is described. Specific features of originating in the flow separation on a smooth surface in a narrow channel are examined, and mechanisms controlling the separation are proposed. Flow separation directly affects the changes in the shape and structure of striations and is the one of main reason for the worse quality of the laser cut surface. It is shown that the changes in the structures of striations over the thickness of the sheet being cut are closely related to aerodynamic features of jet flows of the assisting gas in the cut channel. (C) 2008 Elsevier Inc. All rights reserved.