倾斜和肋化靶面阵列射流冲击换热特性研究

发布时间：2018-01-06 12:05

本文关键词：倾斜和肋化靶面阵列射流冲击换热特性研究　出处：《南京航空航天大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着高效节能发动机的发展,对航空发动机各部件效率、寿命和安全性也提出越来越高的要求,航空发动机叶尖间隙控制是上述目标实现的一个重要保证。本文针对某型多级低压涡轮主动间隙控制装置中冷却空气系统,通过合理的简化,抽象出典型换热单元进行试验研究,为其改进设计提供基础数据参考。首先分别针对单根冷却管和多冷却管冲击倾斜靶面,开展了换热特性试验研究。重点分析冲击Re数(6000、9000、12000),冲击间距比H/d(2.73、4.55、6.36)对换热效果的影响,并通过比较单冷却管与多冷却管不同条件下,靶面特定位置上换热系数的差异来研究多冷却管工况中上游管冲击形成横流的影响。研究中发现,由于冷却管沿程空气出流量的变化,使得靶板表面在沿着冷却管流向上,局部Nu先减小后增大。多冷却管阵列冲击时,冲击产生的横流会进一步提升靶面的换热系数。试验结果表明,随着冲击Re数的增加,靶面换热效果提升明显。冲击间距比H/d减小后,也能提高靶面的换热系数。本文的研究工况中,靶面换热效果在H/d=2.73时达到最佳值。随后本文试验研究了非规则阵列冲击带肋靶板的换热特性,分析了冲击Re数(2000-15000),冲击孔间距比Sy/d(4-20)、冲击间距比Sz/d(6、8、10)对换热效果的影响。研究中发现,靶面存在高肋后,显著改变了靶面的冲击换热效果。在斜向冲击和靶面高肋的共同作用下,冲击滞止点周边5倍冲击孔直径的范围内均有较好的强化换热效果。试验结果表明:靶面换热系数随着冲击雷诺数Re的增加而变大。冲击间距比Sz/d对平均Nu数影响非单调,小冲击Re数工况下,大冲击间距比能够获得较高的换热系数,而在高冲击Re数工况下,小冲击间距有助于提高强化换热效果。当冲击孔间距比Sy/d减小时,靶面平均换热系数增加显著。
[Abstract]:With the development of high efficiency and energy saving engine, the efficiency, life and safety of aero-engine components are required more and more. The tip clearance control of aero-engine is an important guarantee to achieve the above goal. In this paper, the cooling air system in a multi-stage low-pressure turbine active clearance control device is reasonably simplified. Abstract the typical heat transfer unit for experimental study to provide basic data for the improvement of the design. First, the single cooling tube and the multiple cooling tube impact on the inclined target. The experimental study on heat transfer characteristics has been carried out with emphasis on the analysis of the impact re number of 6 000 ~ 9 000 ~ (12 000) and the impact spacing ratio of H / D ~ (2. 73) ~ (5) ~ (4.55). 6.36) the effect on the heat transfer efficiency, and by comparing the single cooling tube with the multi-cooling tube under different conditions. The difference of heat transfer coefficient in the specific position of the target surface is used to study the influence of the upstream tube impact on the cross flow in the multi-cooling tube working condition. It is found that the variation of the air flow rate along the cooling tube is due to the change of the heat transfer coefficient. The local Nu decreases first and then increases along the flow direction of the cooling tube. The cross flow produced by the impact will further increase the heat transfer coefficient of the target surface during the impact of the multi-cooling tube array. The experimental results show that the heat transfer coefficient of the target surface will be further increased. With the increase of impact re number, the heat transfer efficiency of target surface is improved obviously. When the impact distance is smaller than H / d, the heat transfer coefficient of target surface can also be increased. The heat transfer effect of target surface reaches the optimum value when H / D = 2.73. Then the heat transfer characteristics of irregular array impacting ribbed target are studied, and the impact re number is analyzed (2000-15000). The effect of the impact hole spacing on the heat transfer efficiency is compared with that of Syr / D _ (4-20) and S _ (z / D ~ (6) / 8 ~ (10)). It is found that there is a high rib on the target surface. The effect of impact heat transfer on the target surface is obviously changed, under the joint action of oblique impact and high rib of the target surface. In the range of 5 times the diameter of the impingement hole around the impingement point, the heat transfer effect is better. The experimental results show that:. The heat transfer coefficient of target surface increases with the increase of impact Reynolds number re. The impact distance ratio Sz/d has a non-monotone effect on the average Nu number. Under the condition of small impact re number, the high impact distance ratio can obtain higher heat transfer coefficient, while under high impact re number condition, the heat transfer coefficient can be obtained. Small impact spacing is helpful to improve the heat transfer efficiency. When the impact hole spacing is smaller than that of Sy/d, the average heat transfer coefficient of the target surface increases significantly.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V231.1

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