Prediction of plateau and peak of pressure in a compression ramp flow with large separation

Hu, Yan-Chao; Zhou, Wei; Yang, Yanguang; Tang, Zhigong

doi:10.1063/5.0024101

Cited by 11 publications

(11 citation statements)

References 35 publications

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“…40,41,43 . The code has been validated and successfully applied for many cases, especially for hypersonic compression ramp flows 8,[39][40][41]45,46 the tilt plate). The normal extent of the computational domain is 0mm ≤ y n ≤ 40mm, y n is the distance to the wall.…”

Section: Numerical Simulation a Govern Equation And Numerical Methodsmentioning

confidence: 99%

“…6(c)), which consists with the theory proposed by MVD. 39 . Thus the pressure plateaus and peaks collapse.…”

Section: Distributions Of Skin Friction Wall Pressure and Wall Heat Fluxmentioning

confidence: 99%

“…Wenzel et al [32][33][34] found that H in become larger with stronger APG. The APG induced by the separation has been provided by the free interaction theory (FIT) 1,35,36 , triple-deck theory 37,38 and MVD 39 . FIT was established by Chapman et al 35,36 argues that the supersonic flow is influenced by the local boundary layer and the inviscid contiguous stream rather than the further development of the interaction, supplying a uniform streamwise variation of normalized pressure.…”

Section: Introductionmentioning

confidence: 99%

“…FIT was established by Chapman et al 35,36 argues that the supersonic flow is influenced by the local boundary layer and the inviscid contiguous stream rather than the further development of the interaction, supplying a uniform streamwise variation of normalized pressure. By minimizing the shock dissipation among all possible configurations, MVD 39 provides accurate predictions of the shock configurations and the corresponding pressure plateaus and peaks.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of separation hysteresis in curved compression ramp

Zhou,

Hu,

Tang

et al. 2021

Preprint

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A new spatial-related mechanism is proposed to understand separation hysteresis processes in curved compression ramp (CCR) flows discovered recently (Hu et al. Phy. Fluid, 32(11): 113601, 2020). Two separation hystereses, induced by variations of Mach number M ∞ and wall temperature T w , are investigated numerically. The two hystereses indicate that there must exist parameter intervals of Mach number [M ∞,s , M ∞,a ] and wall temperature [T w,a , T w,s ], wherein both attachment and separation states can be established stably. The relationships between the aerodynamic characteristics (including wall friction, pressure and heat flux) and the shock wave configurations in this two hystereses are analyzed. Further, the adverse pressure gradient (APG) I sb (x) induced by the upstream separation process and APG I cw (x) induced by the downstream isentropic compression process are estimated by classic theories. The trend of boundary layer APG resistence I b (x) is evaluated from the spatial distributions of the physical quantities such as the shape factor and the height of the sound velocity line. With the stable conditions of separation and attachment, a self-consistent mechanism is obtained when I sb , I cw and I b have appropriate spatial distributions.

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Section: Numerical Simulation a Govern Equation And Numerical Methodsmentioning

confidence: 99%

“…6(c)), which consists with the theory proposed by MVD. 39 . Thus the pressure plateaus and peaks collapse.…”

Section: Distributions Of Skin Friction Wall Pressure and Wall Heat Fluxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanism of separation hysteresis in curved compression ramp

Zhou,

Hu,

Tang

et al. 2021

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“…Some semi-empirical expressions for plateau and peak pressure under certain conditions have been established 31 . Rencently, Hu et al proposed an implicit model based on the minimum viscous dissipation (MVD) theorem for prediction of plateau and peak pressure of compression ramp flows with large separated regions 32 . Li proposed an explicit theretical model combining FIT to predict plateau and peak pressure, which is validated at low-to-medium Reynolds number 33 .…”

Section: Introductionmentioning

confidence: 99%

Hypersonic curved compression ramp flows with bistable states

Tang,

Wang,

et al. 2021

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The bistable states and separation hysteresis in curved compression ramp (CCR) flows, and the corresponding aerothermal characteristics (including wall friction C f , pressure and heat flux St), are studied numerically and theoretically. Direct numerical simulations of separation hysteresis induced by variation of turning angle φ , as well as the influence of inflow Mach number and wall temperature on hysteresis loops, are carried out. Distributions of wall friction, pressure and heat flux are analyzed. Further, emergence of C f 's first and second minima in the separation bubble is interpreted, revealing it is dominated by the adverse pressure gradient (APG) induced by separation and reattachment shocks. The present results and analysis indicate that the reversed-flow singularity of Smith (Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, 1988, 420: 21-52) is less likely to occur in CCR flows. The prediction of peak pressure p pk of separation states confirms the model based on the minimum viscous dissipation theorem (Physics of Fluids, 2020, 32(10):101702). While the pressure overshoot p os can be analyzed by shock-polars with pressure match of compression and expansion process. The correlation between peak heat flux and peak pressure rise of both separation and attachment states is also discussed in terms of the classical power relations.

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Scales and self-sustained mechanism of reattachment unsteadiness in separated shock wave/boundary layer interaction

Zhou,

Hu,

Tang

et al. 2024

J. Fluid Mech.

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The spatio-temporal scales, as well as a comprehensive self-sustained mechanism of the reattachment unsteadiness in shock wave/boundary layer interaction, are investigated in this study. Direct numerical simulations reveal that the reattachment unsteadiness of a Mach 7.7 laminar inflow causes over $26\,\%$ variation in wall friction and up to $20\,\%$ fluctuation in heat flux at the reattachment of the separation bubble. A statistical approach, based on the local reattachment upstream movement, is proposed to identify the spanwise and temporal scales of reattachment unsteadiness. It is found that two different types, i.e. self-induced and random processes, dominate different regions of reattachment. A self-sustained mechanism is proposed to comprehend the reattachment unsteadiness in the self-induced region. The intrinsic instability of the separation bubble transports vorticity downstream, resulting in an inhomogeneous reattachment line, which gives rise to baroclinic production of quasi-streamwise vortices. The pairing of these vortices initiates high-speed streaks and shifts the reattachment line upstream. Ultimately, viscosity dissipates the vortices, triggering instability and a new cycle of reattachment unsteadiness. The temporal scale and maximum vorticity are estimated with the self-sustained mechanism via order-of-magnitude analysis of the enstrophy. The advection speed of friction, derived from the assumption of coherent structures advecting with a Blasius-type boundary layer, aligns with the numerical findings.

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Prediction of plateau and peak of pressure in a compression ramp flow with large separation

Cited by 11 publications

References 35 publications

Mechanism of separation hysteresis in curved compression ramp

Mechanism of separation hysteresis in curved compression ramp

Hypersonic curved compression ramp flows with bistable states

Scales and self-sustained mechanism of reattachment unsteadiness in separated shock wave/boundary layer interaction

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