Numerical simulations of supersonic stator cascades: Assessment of LES and RANS calculations

Lui, Hugo F. S.; Wolf, William; Braun, James; Rahbari, Iman; Paniagua, Guillermo

doi:10.2514/6.2021-2870

Cited by 2 publications

(3 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More details about the stator geometry and the inlet flow conditions can be found in [57]. This flow configuration was also studied in [58],…”

Section: Flow and Mesh Configurationsmentioning

confidence: 99%

Shock-Boundary Layer Interactions in Supersonic Turbine Cascades

Lui,

Ricciardi,

Wolf

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

The physics of shock-boundary layer interactions in a supersonic turbine cascade is investigated through a wall-resolved large eddy simulation. Special attention is given to the characterization of the low-frequency dynamics of the separation bubbles using flow visualization, spectral analysis, space-time cross correlations, and flow modal decomposition. The mean flowfield shows different shock structures formed on both sides of the airfoil. On the suction side, an oblique shock impinges on the turbulent boundary layer, whereas a Mach reflection interacts with the pressure side boundary layer. Instantaneous flow visualizations illustrate elongated streamwise structures on the incoming boundary layers and their interactions with the shocks and separation bubbles. The passage of high-speed (low-speed) streaks through the recirculation bubbles leads to the downstream (upstream) motion of the separation point on both suction and pressure sides, resulting in spanwise modulation of the bubbles. Space-time cross-correlations reveal that the near-wall streaks drive the suction side separation bubble motion, which in turn promotes the oscillations of the reattachment shock and shear layer flapping. Space-time correlations also indicate the existence of a π phase jump in the pressure fluctuations along the separation bubble on the suction side.After this phase jump, a downstream propagating pressure disturbance is observed, while prior to this point, the pressure disturbances dominantly propagate in the upstream direction. Finally, the organized motions in the shock-boundary layer interactions and their corresponding characteristic frequencies are identified using proper orthogonal decomposition. I. INTRODUCTIONSupersonic fluid machinery offers size and cost reduction in high-speed propulsion and power generation systems [1, 2] and for compact hydrocarbon cracking [3]. The detailed analysis of supersonic turbines is challenging predominantly due to the shock-boundary layer interactions (SBLIs) which arise when the detached oblique shock waves forming at the stator/rotor leading edges impinge on the boundary layers of the neighboring airfoils. The shocks impose intense adverse pressure gradients on the boundary layers that may cause flow separation. This, in turn, leads to the formation of separation and reattachment shocks that *

show abstract

“…More details about the stator geometry and the inlet flow conditions can be found in [57]. This flow configuration was also studied in [58],…”

Section: Flow and Mesh Configurationsmentioning

confidence: 99%

Shock-Boundary Layer Interactions in Supersonic Turbine Cascades

Lui,

Ricciardi,

Wolf

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The ratio of specific heats is chosen as 𝛾 = 1.31, the Prandlt number is 𝑃𝑟 = 0.747 and the ratio of the Sutherland constant over inlet temperature is set as 𝑆 𝜇 /𝑇 ∞ = 0.07182. These conditions are chosen based on previous studies [4,5,18]. Therefore, the grid has approximately 68, 000, 000 points.…”

Section: Flow and Mesh Configurationsmentioning

confidence: 99%

“…They can also be a source of flow unsteadiness, where multiple frequencies are excited due to motion of the incident and reflected shock waves, breathing of the separation bubble, besides the incoming turbulent boundary layer. Typically, the shock wave motion leads to strong pressure fluctuations that can compromise the system's structural integrity [2][3][4][5].…”

mentioning

confidence: 99%

Comparison of Shock-Boundary Layer Interactions in Adiabatic and Isothermal Supersonic Turbine Cascades

Lui

Ricciardi

Wolf

et al. 2022

AIAA AVIATION 2022 Forum

Self Cite

View full text Add to dashboard Cite

Wall-resolved large eddy simulations are employed to investigate the shock-boundary layer interactions (SBLIs) in a supersonic turbine cascade. An analysis of the suction side separation bubbles forming due to the SBLIs is presented for adiabatic and isothermal (cooled) walls. Flow snapshots indicate that the separation bubble contracts and expands in a similar fashion for both thermal boundary conditions. However, the skin-friction coefficient distributions reveal a downstream displacement of the separation region when cooling is applied. The separation bubble is also smaller for this setup compared to the adiabatic one. A steeper pressure rise is observed for the isothermal wall downstream of the incident oblique shock, and this occurs because the incident shock wave gets closer to the blade surface when cooling is applied. The Reynolds stresses are computed to investigate the effects of wall temperature on the turbulence activity. While the levels of the tangential stresses are similar for the cases analyzed, those for the wall-normal component are higher for the cooled wall.

show abstract

Numerical simulations of supersonic stator cascades: Assessment of LES and RANS calculations

Cited by 2 publications

References 18 publications

Shock-Boundary Layer Interactions in Supersonic Turbine Cascades

Shock-Boundary Layer Interactions in Supersonic Turbine Cascades

Comparison of Shock-Boundary Layer Interactions in Adiabatic and Isothermal Supersonic Turbine Cascades

Contact Info

Product

Resources

About