A simple estimation method of momentum coefficient of synthetic jet actuator has been proposed. Flow separation over an airfoil can be suppressed sufficiently with the estimated momentum coefficient. At a certain angle of attack (AOA), momentum deficit of boundary layer at front of separation point can be quantified based on Bernoulli's theorem. The function of synthetic jet actuator is deemed to be momentum addition and two stages of the addition corresponding to blowing and suction phases are considered respectively. The required momentum coefficient as well as the associated injection angle is determined preliminarily with the assumption of synthetic jet actuator at front of separation point. Since synthetic jet actuator is usually installed near the leading edge, a modification is introduced to consider the influence of excitation location. Using this method, flow separation over a NACA0015 airfoil is suppressed nearly completely with AOA = 15° and synthetic jet actuator at x/c = 10%. Different angle of attacks corresponding to pre-stall angle, post-stall angle, and deep stall angle have been examined, respectively. Results indicate that the method is effective at pre-stall angle and post-stall angle. However, momentum coefficient will be underestimated when the separation point is upstream to the location of the airfoil's maximum thickness. At deep stall angle, the method is invalid. The estimation method is useful for practices of flow separation control with synthetic jet actuator.

中文翻译：

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翼型流分离控制中合成射流动量系数的估计

提出了一种简单的合成射流致动器动量系数估算方法。使用估计的动量系数可以充分抑制翼型上的流动分离。在一定的攻角（AOA）下，分离点前边界层的动量赤字可以根据伯努利定理进行量化。合成射流致动器的功能被认为是动量增加，并分别考虑了对应于吹气和吸入阶段的两个阶段的增加。所需的动量系数以及相关的喷射角是在假设合成射流致动器位于分离点前方的情况下初步确定的。由于合成射流执行器通常安装在前缘附近，因此引入了修改以考虑激励位置的影响。使用这种方法，在 AOA = 15° 和 x/c = 10% 的合成射流执行器的情况下，NACA0015 翼型上的流动分离几乎完全被抑制。分别研究了对应于前失速角、后失速角和深失速角的不同攻角。结果表明，该方法对预失速角和后失速角均有效。然而，当分离点位于翼型最大厚度位置的上游时，动量系数将被低估。在较深的失速角，该方法无效。该估计方法对于使用合成射流执行器进行流量分离控制的实践很有用。分别研究了对应于前失速角、后失速角和深失速角的不同攻角。结果表明，该方法对预失速角和后失速角均有效。然而，当分离点位于翼型最大厚度位置的上游时，动量系数将被低估。在较深的失速角，该方法无效。该估计方法对于使用合成射流执行器进行流量分离控制的实践很有用。分别研究了对应于前失速角、后失速角和深失速角的不同攻角。结果表明，该方法对预失速角和后失速角均有效。然而，当分离点位于翼型最大厚度位置的上游时，动量系数将被低估。在较深的失速角，该方法无效。该估计方法对于使用合成射流执行器进行流量分离控制的实践很有用。方法无效。该估计方法对于使用合成射流执行器进行流量分离控制的实践很有用。方法无效。该估计方法对于使用合成射流执行器进行流量分离控制的实践很有用。