A wind tunnel experimental investigation of the separated flow over a back-facing ramp at 25° slant angle and equipped with an array of slotted synthetic jets (SJs) actuators for active flow control (AFC) has been conducted at height-based, $h$, Reynolds numbers between 9.41 × 10³ ≤ ${\mathit{Re}}_h$ ≤ 2.55 × 10⁴. Both the baseline, i.e. without control, and controlled cases were inspected by means of surface pressure measurements and planar particle image velocimetry (PIV). This study represents a fundamental investigation of the basic mechanisms promoting the mitigation of the separation by means of the SJ technology. The AFC device consists of an array of twelve finite span slotted SJs having aspect ratio equal to 15, all fed by a common resonant cavity. For the baseline cases, it is found that the streamwise extension of the separated region decreases with increasing ${\mathit{Re}}_h$. This behavior is due to the nature of the boundary layer upstream of the ramp, which is transitional for the lowest ${\mathit{Re}}_h$ and turbulent for the highest one, as is corroborated by velocity PIV measurements within the boundary layer. For ${\mathit{Re}}_h$ = 1.06 × 10⁴, under actuation with momentum coefficient $c_{\mu }$ = 2.75 × 10⁻³ and reduced frequency $F^{+}$ = 0.34, the boundary layer undergoes an increment of the wall shear stress and acceleration at its edge. Phase-locked PIV measurements unveil that coherent vortical structures energize the boundary layer producing a 65% reduction of the extension of the separation bubble with respect to the corresponding baseline case. However, these benefits degrade by increasing the Reynolds number and for lower levels of $c_{\mu }$ and $F^{+}$. Phase-average flow fields reveal the existence of vortical structures over the ramp which determine characteristic wavy patterns of the streamlines. The scattering of the location of the instantaneous vortices taken at fixed phases proves the existence of concentrations of turbulent structures that participate in the buildup of the turbulence.

对在 25° 倾斜角的背面坡道上的分离流进行风洞实验研究，并配备了用于主动流动控制 (AFC) 的开槽合成射流 (SJ) 致动器阵列，已在基于高度的情况下进行， $H$, 雷诺数在 9.41 × 10 ³ ≤${\mathit{关于}}_H$ ≤ 2.55 × 10 ⁴。通过表面压力测量和平面粒子图像测速法 (PIV) 对基线（即无控制）和受控情况进行检查。这项研究代表了对通过 SJ 技术促进分离的基本机制的基本调查。AFC 设备由 12 个有限跨距的长宽比等于 15 的狭缝 SJ 组成，所有这些 SJ 都由一个公共谐振腔供电。对于基线情况，发现分离区域的流向扩展随着增加${\mathit{关于}}_H$. 这种行为是由于斜坡上游边界层的性质，它是最低的过渡层${\mathit{关于}}_H$最高的湍流，边界层内的速度 PIV 测量证实了这一点。为了${\mathit{关于}}_H$ = 1.06 × 10 ⁴，在动量系数驱动下$C_{\mu }$ = 2.75 × 10 ⁻³和降低的频率$F^{+}$ = 0.34，边界层在其边缘承受壁面剪切应力和加速度的增量。锁相 PIV 测量揭示了相干涡旋结构为边界层提供能量，使分离气泡的延伸相对于相应的基线情况减少 65%。然而，这些好处会随着雷诺数的增加和较低水平的$C_{\mu }$ 和 $F^{+}$. 相均流场揭示了斜坡上涡旋结构的存在，这决定了流线的特征波浪模式。在固定相位处获取的瞬时涡流位置的散射证明了参与湍流形成的湍流结构集中的存在。