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附加阻力是衡量进气道性能好坏的一项重要指标。目前国内进气道阻力试验技术尚未达到使用程度,因此附加阻力的取得主要是依靠计算或查阅国外有关文献的图线。NACA TR 1187是较常用的阻力文献之一。该资料上的有关附加阻力的理论计算式已被广泛使用。文献上也有M数1.2以上的皮托进气道附加阻力系数及M数1.6、1.8,半锥角20°、25°的轴对称进气道附加阻力系数的图线可供初步设计时使用。这里介绍的普拉特—惠特尼公司的超音速进气道亚—跨音速附加阻力试验报告,以及通用动力公司沃思堡分公司关于皮托进气道附加阻力的近似计算即是另外的二篇。这二篇文章均符有一些图线。采用这些图线即可简便地得到附加阻力的近似值。在型号设计过程中,我厂曾把文中图线放大使用并把它与详细的理论计算作了粗略的比较,表明在曲线的精度范围内,与理论计算结果是吻合的,故全文译出。最后,把使用这二篇报告中图线所得的结果与理论计算的典型比较图线表示在图A和图B中。上述图线大多是对应尖唇进气道的,对于元唇进气道,附加阻力应加以修正。有的文献上采用K_(ADD)因子。本刊向大家介绍一篇北美公司的试验报告。报告把各种唇口钝度的试验K_(ADD)值绘成曲线,可供参考。
Additional resistance is a measure of the performance of the intake port is an important indicator of good or bad. At present, the in-port resistance test technology has not yet reached the level of use, so the additional resistance is mainly obtained by calculating or referring to the foreign literature. NACA TR 1187 is one of the more commonly used resistance literature. The theoretical calculation of additional resistance on this data has been widely used. The literature also has more than 1.2 M Pito inlet additional drag coefficient and M number 1.6,1.8, half cone angle 20 °, 25 ° axisymmetric inlet additional drag coefficient of the diagram can be used for preliminary design. The Pratt-Whitney Supersampling Sub-Transonic Additional Resistance Test Report presented here, as well as an approximate calculation by General Dynamics Fort Worth Branch regarding Pitot inlet additional resistance, Two. Both articles have some lines. Use these plots to get an easy approximation of additional resistance. In the process of model design, our factory enlarged the drawing line and made a rough comparison with the detailed theoretical calculation. It shows that it is consistent with the theoretical calculation result in the range of the curve accuracy, so the full text is translated. Finally, a typical comparison plot of the results obtained using the plots in the two reports with the theoretical calculations is shown in Figures A and B. Most of the above lines correspond to the tip lip inlet, for the element lip inlet, the additional resistance should be amended. Some literature uses K_ (ADD) factor. This publication introduces a North American company’s test report. The report plots the experimental K_ (ADD) values for various lip blunders for reference.