Post-Processing of Schlieren Images

Prisăcariu, Emilia Georgiana; Prisecaru, Tudor; Vilag, Valeriu; Suciu, Cosmin Petru; Dobromirescu, Cristian; Enache, Marius; Nicoară, Răzvan Edmond

doi:10.13111/2066-8201.2021.13.3.10

Cited by 1 publication

(1 citation statement)

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“…The provided Schlieren optics, in conjunction with a high-speed camera, enable the direct observation of flow and the resulting shock phenomena. A Z-type Schlieren setup [38], illustrated in Figure 6, is configured to visualize the airflow over the airfoils positioned in the optical access area of the wind tunnel. This setup comprises two 11 cm diameter parabolic mirrors, an adjustable slit diaphragm (knife) for light cutoff, a point light source, and a Phantom VEO710 high-speed camera.…”

Section: Experimental Facilitymentioning

confidence: 99%

Effects of Perforated Plates on Shock Structure Alteration for NACA0012 Airfoils

Gall,

Dumitrescu,

Drăgan

et al. 2024

Inventions

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This research investigated a passive flow control technique to mitigate the adverse effects of shock wave–boundary layer interaction on a NACA 0012 airfoil. A perforated plate with a strategically positioned cavity beneath the shock wave anchoring spot was employed. Airfoils with perforated plates of varying orifice sizes (ranging from 0.5 to 1.2 mm) were constructed using various manufacturing techniques. Experimental analysis utilized an “Eiffel”-type open wind tunnel and a Z-type Schlieren system for flow visualization, along with static pressure measurements obtained from the bottom wall. Empirical observations were compared with steady 3D density-based numerical simulations conducted in Ansys FLUENT for comprehensive analysis and validation. The implementation of the perforated plate induced a significant alteration in shock structure, transforming it from a strong normal shock wave into a large lambda-type shock. The passive control case exhibited a 0.2% improvement in total pressure loss and attributed to the perforated plate’s capability to diminish the intensity of the shock wave anchored above. Significant fluctuations in shear stress were introduced by the perforated plate, with lower stress observed in the plate area due to flow detachment from cavity blowing. Balancing shock and viscous losses proved crucial for achieving a favorable outcome with this passive flow control method.

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Section: Experimental Facilitymentioning

confidence: 99%