Direct numerical simulation of hypersonic turbulent boundary layers. Part 4. Effect of  high enthalpy

Duan, Lian; Martı́n, M. Pino

doi:10.1017/jfm.2011.252

Cited by 116 publications

(116 citation statements)

References 31 publications

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“…Negligible difference in spectral estimation is observed within the reported frequency range, when the overall time record is subdivided in 12 segments instead of the baseline number of 8 segments. In addition, the DNS methodology has been extensively validated in previous work for supersonic/hypersonic turbulent boundary layers [22][23][24][25] and for supersonic shock wave-turbulent boundary layer interactions.…”

Section: -25mentioning

confidence: 99%

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Duan

Choudhari

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Reτ ≈ 464. The emphasis is on comparing the primarily vortical pressure signal at the wall with the acoustic freestream signal under higher Mach number conditions. Moreover, the Mach-number dependence of pressure signals is demonstrated by comparing the current results with those of a supersonic boundary layer at Mach 2.5 and Reτ ≈ 510. It is found that the freestream pressure intensity exhibits a strong Mach number dependence, irrespective of whether it is normalized by the mean wall shear stress or by the mean pressure, with the normalized fluctuation amplitude being significantly larger for the Mach 6 case. Spectral analysis shows that both the wall and freestream pressure fluctuations of the Mach 6 boundary layer have enhanced energy content at high frequencies, with the peak of the premultiplied frequency spectrum of freestream pressure fluctuations being at a frequency of ωδ/U∞ ≈ 3.1, which is more than twice the corresponding frequency in the Mach 2.5 case. The space-time correlations indicate that the pressure-carrying eddies for the higher Mach number case are of smaller size, less elongated in the spanwise direction, and convect with higher convection speeds relative to the Mach 2.5 case. The demonstrated Mach-number dependence of the pressure field, including radiation intensity, directionality, and convection speed, is consistent with the trend exhibited in experimental data and can be qualitatively explained by the notion of 'eddy Mach wave' radiation. NomenclatureC p heat capacity at constant pressure, J/(K·kg) C pp Space-time correlation coefficient of the pressure field, dimensionless C v heat capacity at constant volume, J/(K·kg)

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Section: -25mentioning

confidence: 99%

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Duan

Choudhari

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…(6) and DNS is caused by modeling error. Duan and Martin [11] have proposed a improved formula based on Walz equation, which provide better temperature-velocity relation.…”

Section: Walz Equationmentioning

confidence: 99%

“…The results demonstrate that Morkovin's hypothesis and the strong Reynolds analogy (SRA) are still valid for 6  Ma  for a different wall temperature. Recently, Martin [8] and Duan et al [9][10][11] proposed a series of investigations on the compressible turbulence boundary layer over a flat-plate by the temporal evolving DNS, to assess the effects of wall temperature, Mach number and high enthalpy on the Morkovin's hypothesis and SRA. In general, when Ma ∞ =5, Morkovin's hypothesis is still considered valid for different wall temperatures.…”

Section: Introductionmentioning

confidence: 99%

DNS of a spatially evolving hypersonic turbulent boundary layer at Mach 8

Liang

2013

Sci. China Phys. Mech. Astron.

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This paper reports the direct numerical simulation (DNS) for hypersonic turbulent boundary layer over a flat-plate at Ma ∞ =8 with the ratio of wall-to-freestream temperature equal to 1.9, which indicates an extremely cold wall condition. It is primarily used to assess the wall temperature effects on the mean velocity profile, Walz equation, turbulent intensity, strong Reynolds analogy (SRA), and compressibility. The present high Mach number with cold wall condition induces strong compressibility effects. As a result, the Morkovin's hypothesis is not fully valid and so the classical SRA is also not fully consistent. However, some modified SRA is still valid at the far-wall region. It is also verified that the semi-local wall coordinate y * is better than conventional y + in analysis of statistics features in turbulent boundary layer (TBL) in hypersonic flow. DNS, compressibility effects, turbulent boundary layer PACS number(s): 47

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“…The results demonstrate that Morkovin's hypothesis and the strong Reynolds analogy (SRA) are still valid when Ma ∞ up to 7 for different wall temperatures. Martin [24] and Duan et al [25][26][27] proposed a series of investigations on CTBL over a flat-plate by using the temporally evolving DNS to assess the effects of wall temperature, the Mach number and high enthalpy on the Morkovin's hypothesis. In general, when Ma ∞ =5, Morkovin's hypothesis is still valid for different wall temperatures, and with the wall temperature decreasing compressibility effects can be enhanced, but remain insignificant.…”

Section: Introductionmentioning

confidence: 99%

Direct Numerical Simulation on Mach Number and Wall Temperature Effects in the Turbulent Flows of Flat-Plate Boundary Layer

Liang

2014

Commun. Comput. Phys.

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Abstract. In this paper, direct numerical simulation (DNS) is presented for spatially evolving turbulent boundary layer over an isothermal flat-plate at Ma ∞ = 2.25,5,6,8. When Ma ∞ = 8, two cases with the ratio of wall-to-reference temperature T w /T ∞ = 1.9 and 10.03 are considered respectively. The wall temperature approaches recovery temperatures for other cases. The characteristics of compressible turbulent boundary layer (CTBL) affected by freestream Mach number and wall temperature are investigated. It focuses on assessing compressibility effects and the validity of Morkovin's hypothesis through computing and analyzing the mean velocity profile, turbulent intensity, the strong Reynolds analogy (SRA) and possibility density function of dilatation term. The results show that, when the wall temperature approaches recovery temperature, the effects of Mach number on compressibility is insignificant. As a result, the compressibility effect is very weak and the Morkovin's hypothesis is still valid for Mach number even up to 8. However, when Mach number equal to 8, the wall temperature effect on the compressibility is sensitive. In this case, when T w /T ∞ = 1.9, the Morkovin's hypothesis is not fully valid. The validity of classical SRA depends on wall temperature directly. A new modified SRA is proposed to eliminate such negative factor in near wall region. Finally the effects of Mach number and wall temperature on streaks are also studied.

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Direct numerical simulation of hypersonic turbulent boundary layers. Part 4. Effect of high enthalpy

Cited by 116 publications

References 31 publications

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

DNS of a spatially evolving hypersonic turbulent boundary layer at Mach 8

Direct Numerical Simulation on Mach Number and Wall Temperature Effects in the Turbulent Flows of Flat-Plate Boundary Layer

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