Numerical Investigation of Boundary-Layer Height and Actuation-Parameter Effects of a Circular Synthetic Jet Actuator in Crossflow
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| Format: | Preprint |
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2025
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| _version_ | 1866911261248192512 |
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| author | Ho, Howard Essel, Ebenezer Sullivan, Pierre |
| author_facet | Ho, Howard Essel, Ebenezer Sullivan, Pierre |
| contents | Three-dimensional unsteady numerical simulations are performed to investigate the effects of blowing ratio $C_B$ ($0.85 < \overline{U}_j/U_\infty < 1.7$), stroke ratio $L^+$ ($10.6 < \overline{U}_j /(fd) < 21.3$), and boundary-layer height ratio $D^+$ ($2.1<δ/d<8.0$) on circular synthetic jet actuator (SJA) performance in crossflow. Nine cases are examined at constant free-stream velocity $U_\infty$, with systematic independent variation of averaged jet velocity $\overline{U}_j$, actuation frequency $f$ ($200$-$400~\mathrm{Hz}$), and boundary-layer momentum thickness Reynolds number ($170<Re_θ<740$) to isolate the individual effects of these parameters on a circular-nozzle SJA with fixed nozzle diameter $d$ in crossflow. Instantaneous vortical structures exhibited tilted vortex rings with a trailing vortex pair at low actuation frequency; closely packed expelled vortical structures for higher frequency SJAs, and the largest boundary-layer height ratio induced hairpin-like vortices. Near-wall tertiary vortices, which promote downwash and increase wall shear stress, remain coherent longer and have extended spanwise coverage for low $D^+$. Time-averaged boundary-layer profiles and skin-friction distributions reveal that SJAs with low to moderate $D^+$ have the greatest potential for separation control, maintaining increased near-wall momentum over extended streamwise distances. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2511_08899 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Numerical Investigation of Boundary-Layer Height and Actuation-Parameter Effects of a Circular Synthetic Jet Actuator in Crossflow Ho, Howard Essel, Ebenezer Sullivan, Pierre Fluid Dynamics Three-dimensional unsteady numerical simulations are performed to investigate the effects of blowing ratio $C_B$ ($0.85 < \overline{U}_j/U_\infty < 1.7$), stroke ratio $L^+$ ($10.6 < \overline{U}_j /(fd) < 21.3$), and boundary-layer height ratio $D^+$ ($2.1<δ/d<8.0$) on circular synthetic jet actuator (SJA) performance in crossflow. Nine cases are examined at constant free-stream velocity $U_\infty$, with systematic independent variation of averaged jet velocity $\overline{U}_j$, actuation frequency $f$ ($200$-$400~\mathrm{Hz}$), and boundary-layer momentum thickness Reynolds number ($170<Re_θ<740$) to isolate the individual effects of these parameters on a circular-nozzle SJA with fixed nozzle diameter $d$ in crossflow. Instantaneous vortical structures exhibited tilted vortex rings with a trailing vortex pair at low actuation frequency; closely packed expelled vortical structures for higher frequency SJAs, and the largest boundary-layer height ratio induced hairpin-like vortices. Near-wall tertiary vortices, which promote downwash and increase wall shear stress, remain coherent longer and have extended spanwise coverage for low $D^+$. Time-averaged boundary-layer profiles and skin-friction distributions reveal that SJAs with low to moderate $D^+$ have the greatest potential for separation control, maintaining increased near-wall momentum over extended streamwise distances. |
| title | Numerical Investigation of Boundary-Layer Height and Actuation-Parameter Effects of a Circular Synthetic Jet Actuator in Crossflow |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2511.08899 |