Numerical Simulation of Freestream Acoustic Disturbances in Hypersonic Ground Facilities and Their Effect on Boundary Layer Transition

Transcription

1 Numerical Simulation of Freestream Acoustic Disturbances in Hypersonic Ground Facilities and Their Effect on Boundary Layer Transition PI: Lian Duan --- YIP FA Missouri U. of S&T Project Members: Junji Huang, Ryan Krattiger, Chao Zhang 2016 AFOSR High Speed Aerodynamics Portfolio Review Arlington, VA, USA, June 27-30,

2 Background Boundary layer transition data obtain in conventional wind tunnels have an ambiguity cased by high levels of tunnel background disturbances ( Tunnel noise ) < M < < M < 23 Re tr u /U or Cp 10-1 Harvey,

3 Conventional ( noisy ) wind tunnels is essential for testing and evaluating hypersonic vehicles Prohibitive cost of flight test No existing quiet tunnel facilities above Mach 6 Size and Reynolds number limitations of existing quiet tunnels Hypersonic wind tunnels Hypersonic flight noisy free stream quiet free stream Tunnel noise needs to be characterized to reliably extrapolate laminarturbulent transition data collected from noisy tunnels to flight 3

4 Background Disturbance Environment for High-Speed Wind-Tunnel Facilities Acoustic Radiation Test Rhombus Upstream Disturbance Blanchard et al Flow Laminar Tunnel-Wall Boundary Layer Turbulent Tunnel-Wall Transition Boundary Layer Shadowgraph of the radiated noise from a Mach 3.5 tunnel-wall turbulent boundary layer (courtesy of NASA Langley) In a conventional tunnel (M > 2.5), tunnel noise is dominated by acoustic radiation from turbulent boundary layers on tunnel side-walls (Laufer, 1964) 4

5 Acoustic Radiation from High-Speed Turbulent BLs Theory Eddy Mach wave convecting supersonically with respect to free stream (Phillips, 1960; Ffowcs-Williams & Maidanik 1963) Restricted to prediction of intensity, but not the spectrum Experiments Mostly limited to only amplitude, spectra with limited bandwidth; no multi-point statistics (Laufer, 1961, 1964; Kendall, 1970; Rufer, 2000; Bounitch et al. 2011; Masutti et al., 2013; Radespiel et al., 2013) Susceptible to measurement errors/complications (Dolling & Dussauge 1989; Beresh 2011; Ali et al., 2014) 5

6 Approach Understand tunnel acoustic noise using DNS of acoustic radiation from turbulent BLs Test Rhombus Upstream Disturbance Flow Acoustic Radiation Impact to the Air Force: Turbulent Tunnel Wall Boundary Layer The project aim to supports the USAF large-scale wind tunnels currently employed for testing and evaluating hypersonic vehicles by - reconciling measurement differences across facilities - enabling the extrapolation of ground test measurements to flight conditions Facilities that directly benefit from the research include - AEDC Tunnel 9, Mach 6 Ludwieg Tube at WPAFB, Mach 6 Ludwieg Tube at USAFA/TU-Braunschweig, Sandia Hypersonic Wind Tunnel 6

7 Acoustic Radiation from High-Speed Turbulent BLs Our Previous Work Developed a DNS database of BL acoustic radiation (Duan & Choudhari, AIAA , AIAA ; Duan et al., JFM 2014; Zhang et al., AIAA ) M = 2.5, T w /T r = 1.0 Acoustic radiation M = 5.86, T w /T r = 0.76 (M6Tw076) T w /T r = 0.25 (M6Tw025) Freestream condition representative of Purdue Mach 6 Quiet Tunnel M = 14, T w /T r = 0.18 Flat-plate turbulent BL Freestream condition representative of AEDC Tunnel 9 Established the DNS methodology and compared characteristics of radiated noise field with experiments Significant characteristics compared with experiments include fluctuation amplitudes and frequency spectrum 7

8 Acoustic Radiation from High-Speed Turbulent BLS New Results I. Multivariate statistics analysis of the pressure field induced by high-speed turbulent BLs Spatial correlations (time-averaged pressure structures) Spatial-temporal correlations Acoustic radiation propagation speed Lagrangian correlation length Flat-plate turbulent BL Acoustic pressure sources II. DNS of BL acoustic radiation in axisymmetric enclosure - Effect of axisymmetry on turbulent BLs and their acoustic radiation 8

9 DNS methodology Outline Validation & Comparison with experiments Results - Multivariate statistics analysis of the pressure field induced by high-speed turbulent BLs - DNS of BL acoustic radiation in axisymmetric nozzles Summary and future work 9

10 DNS Setup Case M6Tw076 WENO (Jiang & Shu 1996, Martin et al. 2007) Uniform grid in streamwise-spanwise directions Δx + 9.9, Δy Δz + w 0.5, N z = 20 for z + < 10, Δz + 5.2, N z = 185 for z < N x x N y x N z = 2500 x 460 x 540 (Total: 621 M) Grids designed to simultaneously resolve both the hydrodynamic disturbances and nearacoustic field Inflow BC: Recycling/rescaling (Xu & Martin, 2004) + dynamic translation (Morgan et al.,2011) + filtering (Duan et al., 2012) M = 5.86, Re θ 9455, Re τ 453, T w /T r

11 DNS Setup Case M14Tw018 M = 14, Re θ 13152, Re τ 633, T w /T r 0.18 Uniform grid in streamwise-spanwise directions Δx , Δy Δz w , N z = 19 for z + < 10, Δz , N z = 186 for z < N x x N y x N z = 2500 x 460 x 540 (Box 1 DNS) N x x N y x N z = 1500 x 460 x 786 (Box 2 DNS) 11

12 Effect of Inflow Boundary Condition omparison of Recycling-Rescaling (RR) and Digital Filtering (DF) Methods M6RR M6DF PSD of freestream p M6DF M6RR Spatial correlation of freestream p Methods of Recycling- Rescaling (RR) and Digital Filtering (DF) predict the same BL radiated acoustic noise field downstream of the inflow adjustment zone (Huang & Duan, AIAA ) 12

13 Comparison with Experiment M = 5.86, T w /T r = 0.76 Mean flow predictions and wall-p frequency spectrum are in good agreement with the measurements in the Boeing/AFOSR Mach 6 Quiet Tunnel under noisy condition 13

14 Wall p Validation of DNS Freestream p M6Tw076 14

15 Numerical Schlieren Visualization M = 14, T w /T r = 0.18 (AEDC Tunnel 9 Condition, AIAA ) Streamwise wall-normal plane (x-z) Spanwise wall-normal plane (y-z) Features of acoustic radiation from high-speed turbulent boundary layers Stochastic broadband Finite spatial coherence Preferred range of orientation for eddy Mach waves Higher inclination than Mach wave direction 15

16 I. Multivariate statistics analysis of the pressure field induced by high-speed turbulent BLs 16

17 Streamwise-Spanwise Correlation C pp (Dx,Dy, z) = z/δ=0 p'(x, y, z,t)p'(x + Dx, y + Dy, z,t) ( p' 2 (x + Dx, y + Dy, z,t) ) 1/2 ( p' 2 (x, y, z,t) ) 1/2 z/δ=0.158 M = 5.86, T w /T r = 0.76 z/δ=0.734 z/δ=

18 z/δ ref =0 Spanwise Wall-normal Correlation C pp (Dy, z, z ref ) = p'(x, y, z ref,t)p'(x, y + Dy, z,t) ( p' 2 (x, y, z ref,t)) 1/2 z/δ ref =0.158 ( p' 2 (x, y + Dy, z,t) ) 1/2 M = 5.86, T w /T r = 0.76 z/δ ref =0.734 z/δ ref =

19 Integral Length Scales M = 5.86, T w /T r = 0.76 L x = ò C pp (Dx,0, z)d(dx) L y = ò C pp (0,Dy, z)d(dy) Streamwise and spanwise length scales of p increase with wallnormal height within the boundary layers Freestream p has smaller spatial scales than those in the outer region of the boundary layer 19

20 Streamwise Wall-normal Correlation C pp (Dx, z, z ref ) = p'(x, y, z ref,t)p'(x + Dx, y, z,t) ( p' 2 (x, y, z ref,t)) 1/2 ( p' 2 (x + Dx, y, z,t) ) 1/2 z ref /δ=0 z ref /δ=0.158 M = 5.86, T w /T r = 0.76 z ref /δ=0.734 z ref /δ=2.631 θ xz = 21 20

21 Streamwise Wall-normal Correlation M = 5.86, T w /T r = 0.76 Time-averaged pressure structure in the free stream z ref /δ=2.631 Instantaneous pressure structure in the free stream θ xz = 21 θ xz = 21 C pp (Dx, z, z ref ) = p'(x, y, z ref,t)p'(x + Dx, y, z,t) ( p' 2 (x, y, z ref,t)) 1/2 p' 2 (x + Dx, y, z,t) ( ) 1/2 Vorticity magnitude (colored contours) Numerical schlieren (gray contours) 21

22 Streamwise-spanwise correlation Streamwise wall-normal correlation Spanwise wall-normal correlation Spatial pressure structures as wall-normal distance (z/δ) increases 22

23 Spatial-Temporal Correlation of Pressure Structures pressure structure at t = 0, x = 0 C pp (Δx, 0, 0) with zero time delay pressure structure at t = Δt, x = U c Δt (i) frozen propagation (Taylor s hypothesis) (ii) non-frozen propagation (Propagation + Evolution) (correlation decays) C pp (Δx, 0, 0) with time delay Δt U c Δt Space-time correlation C pp (Δx, 0, 0, Δt) 23

24 Propagation of Pressure Structures M = 5.86, T w /T r = 0.76 Propagation speed defined by finding a value of U c that minimizes the difference between the real time evolution of p(x, t) and a frozen wave p(x U c t) (Del Alamo & Jimenez, JFM 2009) U c º - ( p / t)( p / x) ( p / x) 2 Within most of the boundary layer, U c <u> (similar to incompressible flow results by Kim & Hussain 1993) In the free stream, U c departs from Taylor s hypothesis and is significantly lower than the local mean velocity <u> 24

25 Evolution of Pressure Structures M = 5.86, T w /T r = 0.76 C pp (Δx, 0, 0, Δt) Δt=0 Curve of maximum correlation (C pp ) max Freestream p Δx (C pp ) max measures the rate of evolution and defines the Lagrangian decorrelation length of coherent pressure structures or wavepackets 25

26 Decay of Maximum Spatial-Temporal Correlation M = 5.86, T w /T r = 0.76 Apparent match in Lagrangian scales between the freestream pressure structures and the near-wall eddies that radiate (consistent with the Mach wave radiation concept) 26

27 Sources of Freestream Acoustic Radiation M = 5.86, T w /T r = 0.76 Acoustic analogy (Phillips 1960) Wave Operator Acoustic source term Linear source Nonlinear source Nonlinear source (NLS) dominates over linear source (LS) Total acoustic source term peaks in the buffer layer (z + pk 20) 27

28 II. DNS of BL acoustic radiation in axisymmetric nozzles 28

29 Acoustic Radiation in Axisymmetric Enclosure Motivation Most hypersonic wind tunnels are axisymmetric Freestream disturbances in the tunnel environment reflect the combined outcome of acoustic radiation from all regions of the tunnel wall DNS of acoustic radiation hypersonic turbulent BLs inside a cylindrical test section facilitate a direct comparison with acoustic radiation from a single wall in an unconfined setting study the effect of axisymmetry on turbulent boundary layers and their freestream acoustic radiation Turbulent Boundary Layer Cylinder Acoustic radiation M >1 δ Flow R 29

30 DNS Setup Case M6Cyl WENO in cylindrical coordinate (Jiang & Shu 1996, Martin et al. 2007) Method for dealing with singularity at the polar axis (Constantinescu & Lele, 2002) Technique to avoid time-step restriction due to the very fine azimuthal spacing near the centerline (Bogey et al. 2011) M = 5.85, Re θ 9660, Re τ 400, T w /T r 0.76 Uniform grid in streamwise and azimuthal directions Δx , Δy w Δz w , N z = 19 for z + < 10, Δz , N z = 186 for z < N x x N y x N z = 1920 x 1216 x 364 Radial grids designed to simultaneously resolve both the hydrodynamic disturbances and acoustic fluctuations radiated by the boundary layers nearly straight nozzle with a divergence angle of θ =

31 Streamwise Evolution of Boundary Layer Parameters Cylinder Flat Plate Case M6Cyl x/δ i = 54 x/δ i = 54 DNS captures the streamwise development of the turbulent boundary layer on the inner surface of the axisymmetric nozzle 31

32 Numerical Schlieren and Vorticity Magnitude A B C Vorticity magnitude (colored contours) + Numerical schlieren (gray contours) A B C Acoustic radiation from the turbulent BLs is stochastic and broadband with finite spatial coherence 32

33 Numerical Schlieren and Vorticity Magnitude Vorticity magnitude (colored contours) + Numerical schlieren (gray contours) Acoustic radiation from the turbulent BLs is stochastic and broadband with finite spatial coherence 33

34 Preferred Orientation of Eddy Mach Waves Preferred orientation of eddy Mach waves radiated from the turbulent boundary layer on the inner wall of the nozzle extends beyond the nozzle axis 34

35 Toward DNS of Acoustic Noise in Full-scale Nozzles of Hypersonic Wind Tunnels Development of numerical tools that scales on DoD HPCMP machines > 14,400 cores on AFRL s Lightning (corresponding to > 20% of the system s peak of 1.2 PFLOP/s), > 28,800 cores on AFRL s Spirit (corresponding to > 40% of the system s peak of 1.5 PFLOP/s) 35

36 Summary A DNS database for acoustic radiation from high-speed turbulent BLs across the broad range of freestream Mach numbers and wall-torecovery-temperature ratios has been established - M = 2.5, Re τ 510, T w /T r = M = 5.86, Re τ 465, T w /T r = 0.25, 0.76 (Purdue Quiet Tunnel) - M = 14, Re τ 461, T w /T r = 0.18 (AEDC Tunnel 9) DNS data are used to study turbulent BL acoustic radiation - multivariate pressure statistics - sources of freestream acoustic radiation - the effect of axisymmetry Computations provide additional details of the anisotropic random field that will be useful for modeling receptivity in conventional tunnels 36

37 Future Work Understand noise source mechanisms using the numerical database - Identify features of the boundary layer fluctuations that are responsible for noise generation - Develop low-order models for freestream noise Further studies of pressure fluctuations in axisymmetric nozzles Mimic boundary-layer transition in a natural setting - Freestream-noise simulation + receptivity computation 37

38 ρ u v w p Future Work Freestream-noise simulation + receptivity computation Stochastic Acoustic disturbance field = A exp [ -iwt iw/u c x + tan( ) z tan( ) y} ] External Forcing F Frequency spectrum R L R N B Receptivity Laminar Oscillator Linear Growth Bypass Transient Growth Propagation Speed Freestream acoustic disturbances radiated from tunnel-wall turbulent boundary layers stochastic variables (Uc, θ, φ, ω, etc) Nonlinear Evolution x tr x turb Laminar Breakdown Inclination angle Turbulent Flow (Choudhari et al. 2003) Provide practical input data regarding the disturbance environment for conducting stability analysis in the context of actual wind-tunnel experiments 38

39 Acknowledgment Dr. Meelan Choudhari for collaboration Prof. Steve Schneider and Dr. Katya Casper for providing wind-tunnel measurements for comparison with DNS Dr. Eric Marineau for his guidance on data analysis for our Mach 14 simulation Financial Support from AFOSR (Award No. FA ) Support from NASA Langley to initiate the project Computational resources are provided by the DoD High Performance Computing Modernization Program and the NASA Advanced Supercomputing Division 39

40 Publications C. Zhang, L. Duan and M. M. Choudhari, Acoustic Radiation from a Mach 14 Turbulent Boundary Layer, AIAA Paper , 54th AIAA Aerospace Sciences Meeting, San Diego, CA, January, J. Huang and L. Duan, Turbulent Inflow Generation for Direct Simulations of Hypersonic Turbulent Boundary Layers and Their Freestream Acoustic Radiation, AIAA Paper , 46th AIAA Fluid Dynamics Conference, Washington, DC, June, C. Zhang and L. Duan, Multivariate Statistics Analysis of the Pressure Field Induced by High-Speed Turbulent Boundary Layers, AIAA Paper , 46th AIAA Fluid Dynamics Conference, Washington, DC, June, L. Duan, M. M. Choudhari and C. Zhang, Pressure Fluctuations Induced by a Hypersonic Turbulent Boundary Layer, Journal of Fluid Mechanics, submitted, 2016.

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