Aerodynamic noise reduction by plasma actuators for a flat plate with blunt trailing edge
Aerodynamic noise reduction by plasma actuators for a flat plate with blunt trailing edge
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DOI：
10.1016/j.jsv.2018.08.029
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发表时间：
2019-01
影响因子：
4.7
通讯作者：
Laith A. Al-Sadawi;T. Chong;Jung‐Hoon Kim
中科院分区：
文献类型：
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作者：
Laith A. Al-Sadawi;T. Chong;Jung‐Hoon Kim
采用三种不同结构的单介质阻挡放电（DBD）等离子体激励器，对椭圆前缘平板钝后缘附近涡脱落窄带噪声进行了主动控制实验研究。这些装置可以在钝后缘附近分别在切向、向下和展向方向上产生电风。在气动声学实验装置内，以平板弦长为基准，在雷诺数为0.75 × 105 ~ 4 × 105范围内，同时进行了声学和流场测量。这些等离子体致动器的交流（AC）输入电压的范围相对较低，< 5 kV。“切向”等离子体致动器在抑制涡旋脱落音调噪声（最大1-2 dB降低）方面不是非常有效，尽管从适当的正交分解计算的尾相干模式的空间分布变得比基线等离子体关闭情况产生的空间分布更紧凑，导致音调频率向更高值的偏移。“向下”等离子体激励器可以几乎完全抑制在音调频率处的涡旋脱落噪声（在4.2kV输入电压下约15 dB降低）。其机理与诱导等离子体射流作为一个虚拟障碍物，以抑制上下分离剪切层之间的相互作用，并延迟旋涡脱落的形成有关。“展向”等离子体致动器可以将流向涡阵列投射到尾流中，并将整个跨度上的涡脱落分隔开，在低输入电压下表现出更上级的音调降噪能力（在3.0 kV下降低约12 dB）。据发现，9和10%和7%之间的自由落体速度的向下和展向等离子体致动器，分别等离子体诱导射流的大小，已经足以实现有效减少的旋涡脱落音调噪声。
An experimental study of active control of the vortex shedding narrowband tonal noise radiated near the blunt trailing edge of a flat plate with elliptical leading edge was performed using three different configurations of the single dielectric barrier discharge (DBD) plasma actuators. These devices can produce electric winds in the tangential, downward and spanwise directions, respectively, near the blunt trailing edge. Acoustics and flow measurements were carried out simultaneously at Reynolds numbers between 0.75 × 105and 4 × 105, based on the flat plate chord length, inside an aeroacoustic facility. The range of alternating-current (AC) input voltages to these plasma actuators was relatively low at < 5 kV. The “tangential” plasma actuator is not very effective in the suppression of vortex shedding tonal noise (maximum 1–2 dB reduction), although the spatial distribution of the wake coherent modes calculated from the proper orthogonal decomposition becomes more compact than that produced by the baseline plasma off case, resulting in a shift of the tone frequency to a higher value. The “downward” plasma actuator can suppress the vortex shedding noise almost completely at the tone frequency (about 15 dB reduction at input voltage of 4.2 kV). The mechanism is related to the induced plasma jet acting as a virtual barrier to inhibit the interaction between the upper and lower separating shear layers, and to delay the formation of the vortex shedding. The “spanwise” plasma actuator, which can project array of streamwise vortices into the wake and compartmentalise the vortex shedding across the span, demonstrated a more superior tonal noise reduction capability at low input voltage (about 12 dB reduction at 3.0 kV). It is found that the plasma-induced jet magnitudes between 9 and 10% and 7% of the freestream velocity for the downward and spanwise plasma actuators, respectively, are already sufficient to achieve an effective reduction of the vortex shedding tonal noise.