Direct Numerical Simulation of Turbulent Pressure Fluctuations over a Cone at Mach 8

Huang, Juan; Duan, Lian; Casper, Katya M.; Wagnild, Ross; Bitter, Neal

doi:10.2514/6.2020-1065

Cited by 9 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The above effects are not taken into consideration here as the maximum temperature is well below the critical temperature for oxygen dissociation (2500 K). Furthermore, it is common to study transitional and turbulent boundary layers at Mach greater than 4 using the calorically perfect gas model, particularly in the range of Mach 4 to 6 18,21,[23][24][25][26][27] . This facilitates studying turbulent near-wall effects in isolation from other assumptions associated with ionized gas models.…”

Section: Computational Methodologymentioning

confidence: 99%

“…The spectrum roll-off follows the same scalings in all cases, as will show in more detail below. It is worth mentioning that DNS can capture at over 21 MHz.At the same time, iLES can resolve frequencies up to 4.3 MHz, which is still significantly higher than most experimental sensors and measurement techniques can achieve 20,21,60 . The frequency range accurately captured by the simulations is limited by the mesh resolution and time.…”

Section: Spectral Analysis Of Acoustic Loadingmentioning

confidence: 97%

“…In another recent publication, Huang et al 21 used DNS to characterize the pressure fluctuations under the turbulent portion of the boundary layer over a sharp 7 degrees half-angle cone at a nominal freestream Mach number of 7.91. The DNS was performed using the non-uniform digital-filtering method to generate inflow turbulence with the mean boundary layer a) Electronic mail: drikakis.d@unic.ac.cy.…”

Section: Introductionmentioning

confidence: 99%

“…b) Electronic mail: konstantinos.ritos@strath.ac.uk profiles and the Reynolds stress tensor at the inflow provided by the pre-cursor RANS. Huang et al 21 compared the characteristics of turbulent pressure fluctuations at the cone surface with those over a Mach 8 flat plate and showed that the inner scaling collapses the wall-pressure power spectra density (PSD) among the different flow configurations.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Flow transition to turbulence and induced acoustics at Mach 6

et al. 2021

View full text Add to dashboard Cite

This paper presents the results of implicit Large Eddy Simulation (iLES) and Direct Numerical Simulation (DNS) for flow and acoustics for transitional and turbulent boundary layer over a flat plate at Mach 6. The DNS was about 50 times more refined grid-wise than iLES. Both DNS and iLES were performed using the same numerical schemes, initial and boundary conditions. We compare the different numerical approaches concerning the shape factor, momentumthickness-based Reynolds number, heat flux on the wall, Reynolds stress, and near-wall acoustics. We perform pressure fluctuations spectral analysis and propose a predictive model. We show that iLES captures pretty accurately the flow and acoustic characteristics in the turbulent region. Differences up to 5 dB occur between iLES and DNS in the transition region. iLES also shifts slightly further downstream the end of the transition and underpredicts the shear stress value peak. The iLES captures the near-wall acoustic spectrum roll-off accurately at low and medium frequencies. It underpredicts high frequencies' content due to grid constraints. Overall, iLES gives excellent results compared to the significantly more refined DNS. The results show that high-order numerical simulations can help adapt and validate semi-empirical models for the engineering design and acoustic loading on hypersonic structures.Flow transition to turbulence and induced acoustics at Mach 6

show abstract

Section: Computational Methodologymentioning

confidence: 99%

Section: Spectral Analysis Of Acoustic Loadingmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Flow transition to turbulence and induced acoustics at Mach 6

et al. 2021

View full text Add to dashboard Cite

show abstract

“…To take advantage of statistical homogeneity in the simulation, this operation is performed at the streamwise sensor position for all azimuthal grid points. The simple averaging used to model the sensing area in DNS was shown to improve adherence to measurements of pressure spectra and intensity (Huang et al 2020). The data from the simulated probe pressure p are processed and concatenated into two vectors in the same manner as the experimental measurements, Assimilation of wall-pressure measurements on a cone These vectors are used as inputs for the following data assimilation framework.…”

Section: Simulation Configurationmentioning

confidence: 99%

Assimilation of wall-pressure measurements in high-speed flow over a cone

2022

View full text Add to dashboard Cite

A nonlinear ensemble-variational data assimilation is performed in order to estimate the unknown flow field over a slender cone at Mach 6, from isolated wall-pressure measurements. The cost functional accounts for discrepancies in wall-pressure spectra and total intensity between the experiment and the prediction using direct numerical simulations, as well as our relative confidence in the measurements and the estimated state. We demonstrate the robustness of the predicted flow by direct propagation of posterior statistics. The approach provides a unique first look at the flow beyond the sensor data, and rigorously accounts for the role of nonlinearity, unlike previous efforts that adopted ad hoc inflow syntheses. Away from the wall, two- and three-dimensional assimilated states both show rope-like structures, qualitatively similar to independent schlieren visualizations. Despite this resemblance, and even though the planar second modes are the most unstable upstream, three-dimensional waves must be included in the assimilation in order to accurately reproduce the wall-pressure measurements recorded in the AFRL Ludwieg Tube facility. The results highlight the importance of three-dimensionality of the field and of the base-state distortion on the instability waves in this experiment, and motivate future measurements that probe the three-dimensional nature of the flow field.

show abstract

Relaminarization effects in hypersonic flow on a three-dimensional expansion–compression geometry

Pandey,

Casper,

Beresh

2024

J. Fluid Mech.

View full text Add to dashboard Cite

This experimental work explores the flow field around a three-dimensional expansion–compression geometry on a slender cone at Mach 8 using high-frequency pressure sensors, high-frame-rate schlieren, temperature-sensitive paint, shear-stress measurements and oil-flow visualizations. The $7^\circ$ cone geometry has a hyperbolic slice which acts as an expansion corner and suppresses the disturbances present in the upstream boundary layer. Downstream of the cone-slice corner, high-frequency boundary-layer disturbances attenuate in all cases. Under laminar conditions, second-mode instabilities from the cone diminish and lower-frequency second-mode waves develop on the slice at a frequency commensurate with the increased boundary layer thickness. For fully turbulent cases, the boundary layer over the slice shows evidence of a two-layered nature with a turbulent outer region and a near-wall region with strong attenuation of high-frequency disturbances and reappearance of lower-frequency instability waves. When a downstream compression ramp is added to the slice, the expanded boundary layer shows enhanced susceptibility to separation such that separation is observed at a $10^{\circ }$ deflection, which is smaller than expected for turbulent conditions. For a $30^{\circ }$ ramp, boundary-layer separation occurs further upstream where the heat flux contours show a decrease in heating that is characteristic of a transitional separation. These results demonstrate the effect of relaminarization caused by an upstream expansion on a subsequent shock-wave/boundary-layer interaction.

show abstract

Direct Numerical Simulation of Turbulent Pressure Fluctuations over a Cone at Mach 8

Cited by 9 publications

References 19 publications

Flow transition to turbulence and induced acoustics at Mach 6

Flow transition to turbulence and induced acoustics at Mach 6

Assimilation of wall-pressure measurements in high-speed flow over a cone

Relaminarization effects in hypersonic flow on a three-dimensional expansion–compression geometry

Contact Info

Product

Resources

About