Concave Bump for Impinging-Shock Control in Supersonic Flows

Schülein, Erich; Schnepf, Christian; Weiß, S.

doi:10.2514/1.j060799

Cited by 10 publications

(7 citation statements)

References 17 publications

(29 reference statements)

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“…Both the experimental results (blue dots) and numerical results (triangles) of the current study show a common and distinct correlation between the scaled plateau pressure and the scaled interaction strength. Additionally, particularly valuable are the data from an earlier numerical study (Schülein, Schnepf & Weiss 2021) (crosses) in a wide Mach number range of , which impressively confirm the empirical correlation. The scatter of the data is relatively low, especially when distinguishing between 2-D simulations and 3-D simulations.…”

Section: Resultssupporting

confidence: 59%

Interaction of a moving shock wave with a turbulent boundary layer

Touré

Schülein

2023

J. Fluid Mech.

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In the present study, the influence of a uniformly moving impinging shock on the resulting shock wave–turbulent boundary layer interaction is numerically investigated. The relative Mach number of the shock front travelling above a flat-plate model varied between 0 and 2.3, while the quasi-steady inflow conditions remained constant with a Mach number of 3. To quantitatively evaluate the effect of shock travelling speed, a well-known scaling method for interaction length in quasi-steady flows was applied as a reference after significant improvements in modelling the effects of Reynolds number and wall temperature using new and existing data. Moreover, previously obtained experimental results for a limited range of travelling speeds were employed to validate the obtained numerical results. Three ranges of shock travelling speeds with distinctly different properties were extracted and quantitatively described using a developed correlation-based approach built on the extended quasi-stationary scaling law. In the first range, the scaled interaction length reaches its maximum for the given interaction strength and can be directly described by the scaling law obtained for quasi-stationary interactions. In the second travelling-speed range, the dependence of the interaction length on the interaction strength is explicitly influenced by the shock movement. With increasing shock travelling speed, the scaled interaction length here decreases significantly faster than in the quasi-stationary reference case. The end of this speed range is reached when the absolute shock front speed has caught up with the maximum speed of sound in the interaction zone, and thus the interaction length has fallen to zero. This travelling-speed limit signifies the transition to the third range, where upstream influence is no longer possible.

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Section: Resultssupporting

confidence: 59%

Interaction of a moving shock wave with a turbulent boundary layer

Touré

Schülein

2023

J. Fluid Mech.

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“…To achieve the first goal, an appropriate turning angle θ E of EC (see figure 4a) needs to be selected, because the SCB essentially works through the beneficial interaction between incident shock and expansion fan generated by the EC. Schülein (2022) proved that the SCB had the best control effect when the θ E was equal to or slightly greater than the incident shock deflection angle. In this paper, the deflection angle θ w of the IS has been solved by the inviscid theory.…”

Section: Discussion Of the Shock Control Strategymentioning

confidence: 97%

“…As introduced in § 1, the SCB is a passive control device with a low-drag profile and good control effect. In particular, the concave-shaped SCB proposed by Schülein (2022) can split strong incident shock into a weaker multi-wave system, which has great potential to reduce the pressure/heating peaks. Inspired by the results of Schülein, a shock control strategy of placing a concave SCB on the shock impingement is proposed.…”

Section: Discussion Of the Shock Control Strategymentioning

confidence: 99%

“…The shock-induced large separation bubble transformed into two small-scale separation bubbles under the control of the deformable bump. Schülein, Schnepf & Weiss (2022) proposed a new SCB contour shape called the concave bump, which is marked by an expansion kink directly at the peak. The highest values of separation-length reduction were up to 100 %.…”

Section: Introductionmentioning

confidence: 99%

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Modelling and shock control for a V-shaped blunt leading edge

et al. 2023

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Hypersonic flow on a V-shaped blunt leading edge (VSBLE) at Mach 12 is numerically investigated. A series of self-induced shock–shock interactions and shock wave/boundary layer interactions (SWBLIs) cause extremely high heat flux peaks on the crotch of the VSBLE. Based on these shock structures, a simplified model that divides the flow field into inviscid and viscous areas is constructed. This model can quickly solve the shock interactions and predict the heating/pressure peaks with high accuracy. Furthermore, a shock control bump (SCB) is placed on the SWBLI region to split the strong incident shock into a weaker multi-wave system. The mechanism study of the SCB shows that the inviscid effect significantly reduces the heating/pressure peaks, and the viscous effect suppresses the SWBLI-induced separation. Finally, a VSBLE with SCBs is numerically investigated. The heat flux peak is reduced by 66 % compared to that without the SCBs. The robustness of the SCB under various working conditions is also evaluated. This paper provides an idea for the simplified solution of complex shock interactions and extends the application of the SCB as a thermal protection device in hypersonic flow for the first time.

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“…The results suggested that the onset of flow separation strongly depends on the Mach number and the wedge angle, where an increase in the Mach number has a tendency to postpone the onset of flow separation at a constant deflection angle, which in turn, leads to a reduction of the separation length. More recently, Schülein et al [43] employed numerical simulations and experiments to investigate the use of a concave bump for impingingshock control considering a wide range of Mach numbers and wedge angles. To verify the effectiveness of the flow control strategy, the authors also studied a baseline configuration without a bump, where similarly to Souverein et al [42], they observed that the size of the separation bubble decreases with increasing Mach number.…”

mentioning

confidence: 99%

Mach number effects on shock-boundary layer interactions over curved surfaces of supersonic turbine cascades

Lui,

Wolf,

Ricciardi

et al. 2024

Preprint

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The effects of inlet Mach number on the unsteadiness of shock-boundary layer interactions (SBLIs) over curved surfaces are investigated for a supersonic turbine cascade using wall-resolved large eddy simulations. Three inlet Mach numbers, 1.85, 2.00, and 2.15 are considered at a chord-based Reynolds number 395000. The curved walls of the airfoils impact the SBLIs due to the state of the incoming boundary layers and local pressure gradients. On the suction side, due to the convex wall, the boundary layer entering the SBLI evolves under a favorable pressure gradient and bulk dilatation. On the other hand, the concave wall on the pressure side imposes an adverse pressure gradient and bulk compression. Variations in the inlet Mach number induce different shock impingement locations, enhancing these effects. A detailed characterization of the suction side boundary layers indicates that a higher Mach number leads to larger shape factors, favoring separation and larger bubbles, while the reverse holds for the pressure side. A time-frequency analysis reveals the presence of intermittent events in the separated flow occurring predominantly at low-frequencies on the suction side and at mid-frequencies on the pressure side. Increasing the inlet Mach number leads to an increase in the time scales of the intermittent events on the suction side, which are associated with instants when high-speed streaks penetrate the bubble, causing local flow reattachment and bubble contractions. Instantaneous flow visualizations show the presence of streamwise vortices developing on the turbulent boundary layers on both airfoil sides and along the bubbles. These vortices influence the formation of the large-scale longitudinal structures in the boundary layers, affecting the mass imbalance inside the separation bubbles.

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Concave Bump for Impinging-Shock Control in Supersonic Flows

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Cited by 10 publications

References 17 publications

Interaction of a moving shock wave with a turbulent boundary layer

Interaction of a moving shock wave with a turbulent boundary layer

Modelling and shock control for a V-shaped blunt leading edge

Mach number effects on shock-boundary layer interactions over curved surfaces of supersonic turbine cascades

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