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为了便于工程上翼型的选取及优化,本文针对三个典型翼型边界层稳定性进行对比分析。首先采用eN方法对翼型SD8020进行转捩预测,并采用萘升华实验法检验数值计算的准确性。再利用该数值方法对比了三种典型翼型上表面的转捩位置、不同弦长雷诺数下的压力系数分布、扰动增长率以及最不稳定扰动波的频率。分析结果表明,在相同弦长雷诺数下,NACA0012最先发生转捩,而NACA64-204和RAE2822都保持着较长的层流区;压力梯度对扰动增长有很大影响;同一翼型随弦长雷诺数增长,转捩点雷诺数变大,而不是工程上常采用的固定值。
In order to facilitate the selection and optimization of engineering airfoils, this paper compares and analyzes the stability of three typical airfoil boundary layers. Firstly, the airfoil SD8020 was predicted by eN method and the numerical calculation accuracy was tested by naphthalene sublimation experiment. Then the numerical method is used to compare the position of the transition of the three typical airfoil upper surfaces, the pressure coefficient distribution under different chord Reynolds numbers, the growth rate of disturbance and the frequency of the most unstable perturbation wave. The results show that the NACA0012 turns first at the same chord Reynolds number, while NACA64-204 and RAE2822 both maintain a longer laminar flow area. The pressure gradient has a great influence on the disturbance growth. The same airfoil Reynolds number growth, turning point Reynolds number larger, rather than the fixed value often used in engineering.