Mach reflection promoted by an upstream shock wave

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Type IV shock interference has two triple points which produce two sliplines, forming a narrow jet that penetrates into the subsonic flow region behind the bow shock. Type IV shock interference in the case that the jet is supersonic has been extensively studied in the past. In this paper, type IV shock interference where the jet is transonic is studied. The transition condition from a supersonic to a transonic jet is identified and the influence of compression Mach waves, created inside the leading portion of the jet due to the pressure gradient outside the jet, on the transition and jet shape is analysed. It is found that these compression waves advance the transition from a supersonic to a transonic jet and make the flow inside the transonic jet have a two-branch structure: the lower branch is subsonic, the upper branch is supersonic and is composed of a combination of compressive and expansive waves. The mechanism by which the two-branch structure is produced is explained.

Section: Introductionsupporting

confidence: 53%

“…Inspired by numerical evidence from the work of Guan et al. (2020), here, we have considered the possibility of the appearance of a transonic jet for type IV shock interference.…”

Section: Discussionmentioning

confidence: 99%

Type IV shock interaction with a two-branch structured transonic jet

Bai

2022

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“…In practice, the shock intensity is an important factor that affects the Mach disk (Tan, Ren & Wu 2006;Guan et al 2020). It is well known that the shock intensity in the major plane of the elliptical ICS is always the largest during the convergence of an elliptical ICS (Zhang et al 2021).…”

Section: Range Of Kink Emergence Prior To the Mach Diskmentioning

confidence: 99%

Kinks on elliptical convergent shock waves in hypersonic flow

Si,

2023

Kinks commonly appear on the convergent shock surface when an internal conical flow deviates from the axisymmetric state. In this paper, the formation mechanisms of kinks on internal conical shocks (ICSs) generated by elliptical ring wedges with typical entry aspect ratios ( $AR{\rm s}$ ) in a Mach 6 flow are revealed using a theoretical method, in which the spatial evolution of the three-dimensional elliptical ICS is converted into a temporal evolution of a two-dimensional elliptical moving shock (EMS) using the hypersonic equivalence principle. To simultaneously track the shock front of the EMS and the disturbances propagating along it, a front-disturbance tracking method (FDTM) based on geometrical shock dynamics is proposed. It is found that the shock–compression disturbances from the same family initially near the major axis catch up with the disturbance initially emitted from the major axis to form kinks on the EMS. The equivalent kink formation positions predicted by the FDTM always lag behind the real kink formation positions on the elliptical ICS because the applicability of the hypersonic equivalence principle decays as the shock strengthens along the incoming flow direction. The accuracy of the equivalent kink formation positions predicted by the FDTM gradually declines with the reduction in $AR$ , but it can be significantly improved for all $AR{\rm s}$ after a modification of the equivalent relationship using the shock angle in the major plane of the elliptical ICS, which provides a new way to solve the kinks on the elliptical ICS.

“…2003), and in internal flows, such as engine inlets and nozzles (Matsuo, Miyazato & Kim 1999; Guan et al. 2020). Shock interactions pose serious concerns to aircraft design, as they are prone to trigger significant increases in local pressure/heating loads on vehicle surfaces (Wieting & Holden 1989).…”

Section: Introductionmentioning

confidence: 99%

“…Shock interactions are fundamental phenomena existing widely in supersonic flow fields. Common examples of shock interactions can be found both in external flows, such as hypersonic vehicle bodies (Grasso et al 2003), and in internal flows, such as engine inlets and nozzles (Matsuo, Miyazato & Kim 1999;Guan et al 2020). Shock interactions pose serious concerns to aircraft design, as they are prone to trigger significant increases in local pressure/heating loads on vehicle surfaces (Wieting & Holden 1989).…”

Section: Introductionmentioning

confidence: 99%

Mach reflection of three-dimensional curved shock waves on V-shaped blunt leading edges

Zhang,

Cheng,

Shi

et al. 2023

Theoretical investigation of the primary Mach reflection (MR) configuration on V-shaped blunt leading edges (VBLEs) forms the focus of this study. By ignoring the secondary interactions, a theoretical method based on a simplified form of the continuity relation is developed to predict the shock configurations, including the detached shock, the Mach stem, the transmitted shock and the triple point. The comparison of the theoretical results with both numerical and previous experimental results shows the reliability of the theoretical approach in predicting shock structures across a wide range of free stream and geometric parameters. The theoretical model provides a detailed comprehension of the occurrence mechanism of inverse MRs on VBLEs and the influence of the free stream and geometric parameters on primary MR configurations. Along with the primary MR configuration, the curved shock or compression waves generated by the crotch are solved and offer insight into the transition from the MR to the regular reflection from the same family (sRR). The increase of the ratio $R/r$ and the free stream Mach number $M_0$ appears to facilitate the transition, while the effect of the half-span angle $\beta$ is non-monotonic. The predicted shock positions allow for the identification of the transition boundary between the primary MR and sRR. It is found that $R/r$ below a threshold (for a set $M_0$ value) produces MR, irrespective of $\beta$ . If this threshold is exceeded, the configuration can transition from the primary MR to sRR and then back to the primary MR as $\beta$ increases.