在工程流体力学教学中引入CFD工程案例的探讨

在长期的工程流体力学教学过程中,发现学生对这门课普遍存在畏难情绪,对复杂的理论知识掌握困难.考虑到工程流体力学的研究方法分为理论分析方法,实验方法和数值方法,而其中数值方法在传统教学中应用的较少,所以试图通过适当增加数值方法的应用来改善教学效果.随着本科生对计算机应用能力的增强以及知识面的逐渐扩展,本文提出增加结合专业背景,理论知识及软件应用的综合案例以满足当前课程及学生发展的需求.     

计算流体力学在炼钢中的应用和发展

介绍了计算流体力学应用到炼钢过程中所面临的边界条件和材料物性数据等问题．并着重评述了钢包精炼和连铸结晶器过程中流动及相关现象研究概况,指出炼钢过程中数值模拟的目标不是获得描述某给定过程的精确数值,而是获取过程知识,特别是获取实验无法得到的信息．数值模拟不能代替实验,相反是扩大实验的内容．将来的炼钢过程数值模拟工作将面临更复杂的三维、时间相关的多相反应系统或气金渣等自由表面问题的挑战．      

以学生为中心的工程流体力学课程体系改革和构建

本文介绍了新工科背景下东北大学能源与动力工程专业工程流体力学课程体系改革的探索。结合笔者多年教学经验，从教学模式、教学内容、教学手段和教学环节等多方面，提出了以学生为中心、以问题为导向的工程流体力学课程体系改革方案及构件要素。     

Numerical investigation of the interaction of the turbulent dual-jet and acoustic propagation

In order to study the interaction between two independent jets, a three-dimensional(3D) transient mathematical model is developed to investigate the flow field and acoustic properties of the two-stream jets. The results are compared with those of the single-stream jet at Mach number 0.9 and Reynolds number 3600. The large eddy simulation(LES) with dynamic Smagorinsky sub-grid scale(SGS) approach is used to simulate the turbulent jet flow structure. The acoustic field is evaluated by the Ffowcs Williams–Hawkings(FW-H) integral equation. Considering the compressibility of high-speed gas jets, the density-based explicit formulation is adopted to solve the governing equations. Meanwhile, the viscosity is approximated by using the Sutherland kinetic theory. The predicted flow characteristics as well as the acoustic properties show that they are in good agreement with the existing experimental and numerical results under the same flow conditions available in the literature. The results indicate that the merging phenomenon of the dual-jet is triggered by the deflection mechanism of the Coanda effect, which sequentially introduces additional complexity and instability of flow structure. One of the main factors affecting the dual-jet merging is the aperture ratio, which has a direct influence on the potential core and surrounding flow fluctuation. The analysis on the noise pollution reveals that the potential core plays a fundamental role in noise emission while the additional mixing noise makes less contribution than the single jet noise. The overall sound pressure level(OASPL) profiles have a directive property, suggesting an approximate 25° deflection from the streamwise direction, however, shifting toward lateral direction of about 10° to 15° in the dual-jet. The conclusion obtained in this study can provide valuable data to guide the development of manufacturing-green technology in the multi-jet applications.