【作者】 张林；

【导师】 张堃元；

【作者基本信息】 南京航空航天大学 ， 航空宇航推进理论与工程， 2014， 博士

【摘要】 针对所有等熵压缩波都汇聚于一点的常规等熵压缩面,为了改善其壁面压力、Ma数分布,本文采用理论分析、数值模拟和风洞试验相结合的方法,研究了一种新型的等熵压缩波分散交汇的曲面压缩系统。论文首先在深入分析常规等熵压缩面设计方法和流场特性的基础上,根据数学中的坐标变换理论,研究了一种等熵压缩程度沿流向可控的新型曲面压缩系统,形成了这种特殊压缩面的设计方法,分析了主要设计参数对压缩流场的影响,并与常规几何截短的等熵压缩面进行了对比。结果表明:等熵压缩型面坐标变换后能够产生分散、不汇聚于一点的等熵压缩波系,这些等熵压缩波依次相汇聚,使得压缩面长度明显缩短并能保持等熵压缩的流动特征,同时其壁面压力、Ma数分布也得到明显改善。压缩系统中等熵压缩波的分散与汇聚最终是由产生这些波系的曲面压缩面决定。为此,根据有旋特征线理论,研究了一种给定壁面压升规律设计曲面压缩系统的方法,并提出一种能够有效改善常规等熵压缩面壁面压力分布的S型压升规律,其前缘部分压力梯度变化的斜率较大而末端部分压力梯度变化的斜率则逐渐减小并趋近于零,这就避免末端出现比较大的逆压力梯度。将壁面采用S型压升规律的曲面压缩系统作为外压缩面设计二维进气道,分析了均匀和非均匀来流条件下的性能,并与相同约束条件下常规压缩二维进气道进行了对比。结果表明:利用弯曲激波压缩气流能够有效缩短进气道外压缩面的长度,并且弯曲激波的形状受来流Ma数变化不敏感以及对气流造成的损失较小,因此改善了非设计状态下进气道的性能。此外,该进气道的性能和流场畸变受非均匀来流影响较小,并且对它还具有一定的校正作用。为了改善等熵压缩面的壁面Ma数分布,直接从压缩系统的减速作用着手将壁面减速规律作为研究对象,研究了一种给定壁面减速规律设计曲面压缩系统的方法。根据等熵压缩型面坐标变换后壁面Ma数分布的变化,研究了壁面Ma数线性分布和二次分布两种常规减速规律,并发展了一种壁面Ma数采用两段连续分布的减速规律设计方法。将不同减速规律的曲面压缩系统应用于高超二维进气道设计,以曲面压缩系统作为进气道的外压缩面,通过数值模拟方法对进气道进行了研究,并与相同约束条件下常规三楔压缩和壁面S型压升规律的进气道进行了对比。结果表明:壁面Ma数二次分布、线性分布减速规律的曲面压缩系统分别与等熵压缩面和x轴坐标缩放因子Sx=0.5的压缩面具有很高的相似性。减速规律分两段设计时更容易控制压缩程度沿流向的变化。尤其是,壁面减速规律可控的曲面压缩系统以等熵压缩为主、激波压缩为辅压缩气流,并且其壁面的压力梯度变化比较适中,将它应用于进气道的设计能够缩短外压缩面的长度、减小流动损失,这样进气道的总体性能就得到显著提高。为了发挥壁面压升规律与减速规律可控曲面压缩系统的优势,结合几种典型曲面压缩系统的对比研究,从几何方式组合和气动方式组合两个方面探索了壁面采用压力/Ma数复合分布规律的曲面压缩系统设计方法,并对比分析了两种组合压缩型面的参数分布和性能特点。将组合压缩型面作为外压缩面设计二维进气道,分析了其性能并与文献中进气道进行对比。结果表明:采用几何和气动方式组合能够更充分发挥壁面按单一参数设计所得曲面压缩系统的优势,有效改善壁面参数的分布规律,使得壁面参数分布趋于更加合理。进气道采用组合压缩型面后能够减小流动损失,使得总体性能得到显著提高。在几种典型曲面压缩系统的对比研究基础上,论文最后将壁面Ma数线性减速规律的曲面压缩系统应用到带顶压的三维侧压式进气道中,在确保进气道的外形尺寸、总压缩量和侧板压缩方式均相同的情况下,分别改进参考侧压式进气道的顶板和侧板,并进行对比研究,最终设计出顶板和侧板均采用曲面压缩系统的双侧曲面压缩侧压式进气道。数值研究表明:顶板、侧板采用曲面压缩系统后,采用较弱的前缘激波压缩与曲面的等熵压缩相结合的方式压缩气流,唇口溢流窗相对较小,在整个Ma=4~7工作范围内,进气道都具有较高的压缩效率和流量捕获能力。风洞试验结果表明:设计与非设计状态下,进气道顶板和侧板沿程压力分布均具有壁面Ma数线性减速规律的曲面压缩系统的特征。设计状态Ma=6时进气道的总压恢复系数为0.544,出口马赫数为2.70,增压比为28倍。更多还原

【Abstract】 In order to improve the wall pressure and Mach number distribution of the conventional isentropic surface having focused isentropic compression waves, a detailed study is performed on the new curved compression system with isentropic compression waves decentralization-intersection by theoretically analysis, numerical simulation and wind tunnel testing.Firstly, a new curved compression system with controlled isentropic compression degree along the flow direction is investigated using the coordinate transformation theory through analyzing the conventional isentropic surface design methodology and flow field characteristics. The special compression surface is parametric studied and compared with the conventional geometric truncated isentropic surface. Results show that the compression surface can produce decentralized and not focused isentropic compression waves. These waves converge orderly. The compression surface length is shortened obviously and maintains the isentropic compression flow characteristic. Meanwhile, its wall pressure and Mach number distributions are improved.The isentropic compression waves decentralization and convergence are determined by the curved surface. Therefore, the curved compression system with given the wall pressure rise law is investigated using the rotational method of characteristics, and an S type pressure rise law is proposed. Its front pressure gradient change slope is larger, but the terminal slope decreases gradually towards zero. The surface end will not appear larger adverse pressure gradient. The surface using S type pressure rise law is applied to design two-dimensional inlet. At uniform and non-uniform conditions, the performance is compared with normal compression inlets under the same design conditions. Results show that the external surface length can be shortened effectively by using curved shock which is not insensitive to the Mach number variation and causes less loss. So the off-design performance is improved. Moreover, the performance and flow distortion are slightly influenced by non-uniform flow.In order to improve the wall Mach number distribution of isentropic surface, the curved compression system with given the wall deceleration law is investigated directly from the effect of deceleration function. The wall Mach number linear and quadratic distribution normal deceleration laws are studied according to isentropic surface coordinate transformation. Then a deceleration law with wall Mach number using two stages distribution is developed. Curved surfaces with different wall deceleration laws are used to design hypersonic two-dimensional inlets, and compared with normal three-wedge and S type pressure rise law inlet under the same design conditions. Results show that the curved surfaces with wall Mach number quadratic and linear distribution have high similarity with isentropic surface and X axis coordinate scaling factor Sx=0.5 surface respectively. It is easier to control the flow direction compression degree change, when the deceleration law is divided into two stages. Especially, curved surface with controlled wall deceleration law combines mainly isentropic compression with little shock compression to compress airflow, and its wall pressure gradient changes relatively moderate. The inlet external surface length is shortened and the loss is reduced, so its overall performance is increased significantly.In order to take advantage of curved surfaces with controlled wall pressure rise law and deceleration law, the curved compression system with wall pressure and Mach number complex distribution is investigated from the two aspects: geometric and aerodynamic combination. The two kinds of combination surface are compared and used to design inlet based on the reference inlet. Results show that the advantages of curved surface designed by a single parameter are performed using geometric and aerodynamic combination. The wall parameter distributions are improved effectively and tend to be more reasonable. The inlet with combination surface can reduce the flow loss, so the overall performance is increased significantly.Comparison of several typical curved surfaces, the curved surface with wall Mach number linear distribution is applied to improve topwall and sidewall of reference three-dimensional sidewall compression inlet under the same configuration, total compression and sidewall compression mode, and compared with the reference inlet. The curved compression sidewall inlet with both topwall and sidewall using curved surface is obtained. Numerical results show that the inlet combines isentropic compression with weaker shock compression to compress airflow, and the spillage window is smaller. Therefore, the inlet has higher compression efficiency and flow capture capacity in the entire operating range of Ma=4~7. Experimental results show that topwall and sidewall pressure distribution have curved surface characteristics at design and off-design conditions. At Ma=6, the inlet has a total pressure recovery of 0.544, an exit Mach number of 2.70, a compression ratio of 28.更多还原