小冲击间距下带倾角冲击凹柱面流场结构实验研究

Experimental investigations for the flow structures on the concave surface with inclined impingement in small distance

关键词:  带倾角冲击  凹柱面  流场显现  旋流结构

Key words:  Inclined impingement  Concave surface  Flow visualization  Vortex structures

摘要:

针对带倾角冲击凹柱面靶板的流动特性和流场结构研究,采用烟线法开展了流场显现实验研究,重点分析了旋流产生和发展的规律。试验中通过改变冲击雷诺数、冲击间距比(冲击间距和冲击孔直径之比)、冲击角度以及凹柱面相对曲率等参数,分析了涡出现的位置、结构等随这些参数的变化规律。研究结果表明:由于冲击射流同周围静止空气之间的粘性作用、气体在凹柱面上运动、脱离的共同作用下,带倾角冲击凹柱面靶板产生了不同的旋流结构。实验中,随冲击雷诺数的增加,在冲击滞止区域两侧流体冲击靶板分离处的圆心角增大,分离推迟;由于冲击角度的影响,相对冲击角度较小侧射流与壁面分离比在较大侧提前,且在相对冲击角度较小侧更容易产生旋流结构。实验中改变的参数均影响了旋流结构及其发展特性,并且影响规律表现出较强的关联性。

Abstract:

Experiments were carried out to investigate the flow structures on concave surface with inclined impingement in a limited narrow space. Smoke wire flow visualization was used to study the characteristics of the flow structures of a round jet inclined impinging on the concave surfaces. Jet Reynolds number,the ratio of jet impingement distance to the diameter of the jet hole,inclined jet angle and the relative curvature were changed to study the rules of flow structures varying with these parameters. The experimental results show that the central angle of the impingement fluid separating from target surface becomes larger as increasing Reynolds number and flow separation is delayed. Because of the influence of inclined jet,it was easier to generate swirl vortex structures at relatively smaller angle side of inclined impingement than the relatively larger central angle side,and the separating at relatively smaller angle side was brought forward. All the results indicate that the vortex structures were affected by all above parameters at the same time,and the rules of vortex structures varying with these parameters are strongly correlated.