Boundary layer and near wake measurements of a two-dimensional airfoil with background-oriented schlieren method

Zhu, Wenbo; Bons, Jeffrey P.; Gregory, James W.

doi:10.1007/s00348-022-03550-2

Cited by 4 publications

(1 citation statement)

References 33 publications

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“…where y + is the dimensionless distance from the wall, y is the distance from the wall, uτ is the wall stress shear velocity, v is the kinematic viscosity of the fluid [19]. According to Figure 2, the near-wall area is usually in the range of y + ≤100.…”

Section: Boundary Layer Theorymentioning

confidence: 99%

Investigation on drag reduction performance of rotating blade surface with micro-texture

Zhu,

Zhang,

et al. 2024

Preprint

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For enhance the aerodynamic performance of aero engine blades, the parameters and drag-reduction mechanism of micro-texture to reduce blade surface flow loss are investigated in this study. First, a simplification simulation method is proposed to reduce the calculation cost and determine the aerodynamic parameters of the blade model through the comparison of flow field characteristics and parameters of the blade simulation result. Secondly, the placement position and geometrical parameters of micro-texture with lower energy loss are determined by CFD (Computational Fluid Dynamics) simulation for the established micro-texture on the blade surface and the drag reduction mechanism is analyzed based on the simulation result. The triangular rib with a depth of 0.2mm and width of 0.3mm has the best drag reduction performance, and this micro-texture has an energy loss coefficient reduction of 1.45% and a drag reduction of 1.31% on a single blade. Finally, the blades with the optimal micro-texture parameters are tested in the intermittent wind tunnel. The experimental results show that the micro-texture decreases the energy loss by 3.7% of a single blade under the working conditions of 57° attack angle and 136.24m/s, which is pleasing for the drag reduction performance of the integral impeller with 45 blades.

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Section: Boundary Layer Theorymentioning

confidence: 99%

Investigation on drag reduction performance of rotating blade surface with micro-texture

Zhu,

Zhang,

et al. 2024

Preprint

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A non-axisymmetric temperature field reconstruction method based on the compressive sensing background oriented Schlieren method

Wu,

Pan,

Zhang

et al. 2024

Physics of Fluids

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Measurement of the combustion temperature field is an extremely important issue in industrial production. Temperature is one of the key parameters in combustion studies. With the temperature field distribution of the combustion field obtained, heat transfer, heat convection, and heat radiation can be calculated directly and efficiently. Traditional background oriented Schlieren (BOS) is an effective method for non-axisymmetric temperature field measurements, but it requires simultaneous Schlieren imaging at multiple angles for tomographic reconstruction, which will greatly limit its application. In this paper, the compressive sensing algorithm is introduced into the temperature field reconstruction, which establishes the system of equations between the deflection angle and the refractive index gradient. Then, the reconstruction of the non-axisymmetric temperature field is realized by solving the underdetermined system of equations by the method of solving the sparse solution through the compressive sensing. First, light offsets across the non-axisymmetric temperature field are measured by the under-angled BOS system and image processing method. Second, the spatial refractive index field is reconstructed by the compressive sensing BOS method proposed in this paper. Finally, the spatial temperature field is obtained. The experimental results show that by comparing the iRadon reconstruction algorithm and the compressive sensing reconstruction algorithm, the temperature field reconstructed by the compressive sensing under the condition of the under-angled sampling of projection data had a higher accuracy than that reconstructed by the tomographic reconstruction algorithm under the same condition. The average error of the temperature field was reduced from 34.6 to 29.7 K under the same measurement conditions; however, the accuracy is better maintained by using the compressive sensing algorithm under the condition of undersampling projection.

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Forward and Inverse Modeling of Depth-of-Field Effects in Background-Oriented Schlieren

Molnar,

LaLonde,

Combs

et al. 2024

AIAA Journal

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This paper reports a novel cone-ray model of background-oriented schlieren (BOS) imaging that accounts for depth-of-field effects. Reconstructions of the density field performed with this model are far more robust to the blur associated with a finite aperture than conventional reconstructions, which presume a thin-ray pinhole camera. Our model is characterized and validated using forward evaluations of simulated buoyancy-driven flow and both simulated and experimental BOS measurements of hypersonic flow over a sphere. Moreover, the model is embedded in a neural reconstruction algorithm, which is demonstrated with a total variation penalty and the compressible Euler equations. Our cone-ray technique dramatically improves the accuracy of BOS reconstructions: the shock interface is well-resolved in all our tests, irrespective of the camera’s aperture setting, which spans f-numbers from 22 down to 4.

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Boundary layer and near wake measurements of a two-dimensional airfoil with background-oriented schlieren method

Cited by 4 publications

References 33 publications

Investigation on drag reduction performance of rotating blade surface with micro-texture

Investigation on drag reduction performance of rotating blade surface with micro-texture

A non-axisymmetric temperature field reconstruction method based on the compressive sensing background oriented Schlieren method

Forward and Inverse Modeling of Depth-of-Field Effects in Background-Oriented Schlieren

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