Shock Wave Diffraction Phenomena around Slotted Splitters

Gnani, Francesca; Lo, Kin Hing; Zare‐Behtash, Hossein; Kontis, Konstantinos

doi:10.3390/aerospace2010001

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…Gnani et al 11 employed splitters with a spike-shaped structure to produce shock diffraction and visualized the shock and turbulence phenomena using schlieren photography. They observed that the reflected shock waves were distorted during the process of passing through the vortex, but remained continuous and were not cut off by the vortex.…”

Section: A Backgroundmentioning

confidence: 99%

Numerical investigation of rarefied vortex loop formation due to shock wave diffraction with the use of rorticity

2021

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When compressed gas is ejected from a nozzle into a low-pressure environment, the shock wave diffracts around the nozzle lip and a vortex loop will form. The phenomenon has been widely investigated in the continuum flow regime, but how the shock diffraction and vortex behave under rarefied flow conditions has not received as much attention. It is necessary to understand this transient flow in rarefied environments to improve thrust vector control and avoid potential contamination and erosion of spacecraft surfaces. This work provides numerical results of the vortex loop formation caused by shock wave diffraction around a 90 • corner using the direct simulation Monte Carlo method and the compressible Navier-Stokes equations with the appropriate Maxwell velocity slip and the von Smoluchowski temperature jump boundary conditions. The Mach number and rarefaction effects on the formation and evolution of the vortex loop are discussed. A study of the transient structures of vortex loops has been performed using the rorticity concept. A relationship of mutual transformation between the rorticity and shear vectors has been discovered, demonstrating that the application of this concept is useful to understand vortex flow phenomena.

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Section: A Backgroundmentioning

confidence: 99%

Numerical investigation of rarefied vortex loop formation due to shock wave diffraction with the use of rorticity

2021

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“…It is recognized that the optical flow visualization is the most suitable method to observe the shock structures in the compressible flow. Authors in [31] qualitatively investigated and experimentally visualized the shock wave diffraction phenomena around two splitters with spike-shaped structures for different Mach numbers. Schlieren photography was used to obtain an insight into the sequential diffraction processes that take place in different planes and as a result, a complete description of the main flow features was successfully provided.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…The whole gas flow was imaged using a spherical mirror with focal length of 2000 mm and diameter of 300 mm. Furthermore, for detailed images including the intermittent shock structures (Mach disks), a smaller spherical mirror with focal length of 650 mm and diameter of 63 mm was used [23,[31][32][33].…”

Section: Experimental Set-upmentioning

confidence: 99%

Investigation on the Inert Gas-Assisted Laser Cutting Performances and Quality Using Supersonic Nozzles

Orazi

Darwish

Reggiani

2019

Metals

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In the present work, three different supersonic nozzles were designed and manufactured to operate at various stagnation pressures during laser cutting. Several cutting experiments were performed on stainless steel samples of various thicknesses (2, 4, 6 mm) using a fiber laser of 3 kW with a head adapted to fit with both the proposed supersonic nozzles and a commercial reference conical nozzle. The flow through these nozzles was numerically modeled and compared with the Schlieren visualization measurements. The mass flow rate, the Mach number, and the pressure distributions were selected in detail in order to analyze the dynamic characteristics of the exit jet and to comparatively assess the achieved cutting quality (roughness perpendicularity) and capability (maximum thickness, cutting speed). The numerical and the experimental results were found to be in high agreement in terms of the flow structure and mass flow rate. In addition, a significant reduction of the assistance gas consumption of up to 65% on average was achieved by using supersonic nozzles as opposed to conical ones, accompanied with the decrease of the operating pressure and the increase of the cutting speed.

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“…In this regard, a comprehensive review of various methods to attenuate shock/blast waves was reported by Igra et al [ 2 ] addressing both experimental and numerical approaches. Essentially, shock-wave attenuation by geometrical means such as rigid barriers or sudden changes in the flow geometries is governed by compression, rarefaction regions arising from shock diffraction and intense shock-turbulence interactions [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. These involve multiple wave interactions, reflecting from surrounding boundaries and complex shock-shock, shock-vortex and shock-boundary layer interactions.…”

Section: Introductionmentioning

confidence: 99%

On Shock Propagation through Double-Bend Ducts by Entropy-Generation-Based Artificial Viscosity Method

Chaudhuri

2019

Entropy

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Shock-wave propagation through obstacles or internal ducts involves complex shock dynamics, shock-wave shear layer interactions and shock-wave boundary layer interactions arising from the associated diffraction phenomenon. This work addresses the applicability and effectiveness of the high-order numerical scheme for such complex viscous compressible flows. An explicit Discontinuous Spectral Element Method (DSEM) equipped with entropy-generation-based artificial viscosity method was used to solve compressible Navier–Stokes system of equations for this purpose. The shock-dynamics and viscous interactions associated with a planar moving shock-wave through a double-bend duct were resolved by two-dimensional numerical simulations. The shock-wave diffraction patterns, the large-scale structures of the shock-wave-turbulence interactions, agree very well with previous experimental findings. For shock-wave Mach number M s = 1.3466 and reference Reynolds number Re f = 10 6 , the predicted pressure signal at the exit section of the duct is in accordance with the literature. The attenuation in terms of overpressure for M s = 1.53 is found to be ≈0.51. Furthermore, the effect of reference Reynolds number is studied to address the importance of viscous interactions. The shock-shear layer and shock-boundary layer dynamics strongly depend on the Re f while the principal shock-wave patterns are generally independent of Re f .

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Shock Wave Diffraction Phenomena around Slotted Splitters

Cited by 5 publications

References 33 publications

Numerical investigation of rarefied vortex loop formation due to shock wave diffraction with the use of rorticity

Numerical investigation of rarefied vortex loop formation due to shock wave diffraction with the use of rorticity

Investigation on the Inert Gas-Assisted Laser Cutting Performances and Quality Using Supersonic Nozzles

On Shock Propagation through Double-Bend Ducts by Entropy-Generation-Based Artificial Viscosity Method

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