sbpw3 propagation workshop sboom updated · 2020-02-05 · sriram k. rallabhandi aeronautics...
TRANSCRIPT
Sriram K. Rallabhandi
Aeronautics Systems Analysis Branch
NASA Langley Research Center
Hampton, VA 23681
SBPW3: Propagation Workshop Results using sBOOM
5th January, 2020, Orlando, FL, USAAIAA SciTech 2020
SBPW3: sBOOM results 2
• Summary of Cases Analyzed • Boom Propagation Code Details • Cases
• Ground Signatures • Loudness metrics
• Highlights • Summary
Outline
5 January 2020
SBPW3: sBOOM results 3
Summary of Cases Analyzed
5 January 2020
• NASA trimmed low-boom concept - C25P
– Required runs with measured atmospheric profiles
– Lateral cut-off analysis – Optional focus boom simulations
SBPW3: sBOOM results 3
Summary of Cases Analyzed
5 January 2020
• NASA trimmed low-boom concept - C25P
– Required runs with measured atmospheric profiles
– Lateral cut-off analysis – Optional focus boom simulations
• NASA-Lockheed Low-Boom Flight Demonstrator (LBFD): A variant of X-59 QueSST
• Required runs with measured and standard atmospheres
SBPW3: sBOOM results 4
sBOOM • Propagation based on lossy Quasi-1D Burgers equation
Propagation Prediction Code: sBOOM
5 January 2020
𝜕𝑝𝜕𝜎
=𝜕𝐵𝜕𝜎
𝐵𝑝 +
𝛽Ω2𝜌0𝑐3
0 ( 𝑐0
𝑣𝑔 ) 𝜕𝑝2
𝜕𝜏+
𝛿Ω2
2𝜌0𝑐30 ( 𝑐0
𝑣𝑔 ) 𝜕2𝑝𝜕𝜏2
+ ∑𝜈
𝑚𝜈
2𝑐0
𝑡𝜈Ω2
1 + 𝑡𝜈Ω𝜕𝜕𝜏
( 𝑐0
𝑣𝑔 ) 𝜕2𝑝𝜕𝜏2
𝐵 =𝜌𝑐𝑆0𝐷2
0
𝜌0𝑐0𝑆𝐷2
𝑐𝑣𝑔0
𝐷0𝑐0𝑣𝑔
𝐷
, 𝑣𝑔 = 𝑐 . �̄� + �̄� , D = 1 +�̄� . �̄�
𝑐, Ω =
1𝐷
𝑑𝑥𝑑𝑡
= �̄� + 𝑐2𝑞𝐷𝑑𝑞𝑑𝑡
= − [ ∇𝑐𝑐𝐷
+ 3
∑𝑖=1
𝑞𝑖 ∇𝑤𝑖] 𝑞 =�̄�
𝑐 + �̄� . �̄�
• Ray Path Equations:
SBPW3: sBOOM results 4
sBOOM • Propagation based on lossy Quasi-1D Burgers equation
Propagation Prediction Code: sBOOM
sBOOM is under active development. Contact [email protected] to get a copy of sBOOM
• Features and capabilities • Under-track, off-track signatures with
winds • Acceleration, turn-rates, climb-rates,
maneuvers and focus predictions by interfacing with Lossy Nonlinear Tricomi Equation (LNTE)
• Design friendly sensitivities and adjoint error estimates
5 January 2020
𝜕𝑝𝜕𝜎
=𝜕𝐵𝜕𝜎
𝐵𝑝 +
𝛽Ω2𝜌0𝑐3
0 ( 𝑐0
𝑣𝑔 ) 𝜕𝑝2
𝜕𝜏+
𝛿Ω2
2𝜌0𝑐30 ( 𝑐0
𝑣𝑔 ) 𝜕2𝑝𝜕𝜏2
+ ∑𝜈
𝑚𝜈
2𝑐0
𝑡𝜈Ω2
1 + 𝑡𝜈Ω𝜕𝜕𝜏
( 𝑐0
𝑣𝑔 ) 𝜕2𝑝𝜕𝜏2
𝐵 =𝜌𝑐𝑆0𝐷2
0
𝜌0𝑐0𝑆𝐷2
𝑐𝑣𝑔0
𝐷0𝑐0𝑣𝑔
𝐷
, 𝑣𝑔 = 𝑐 . �̄� + �̄� , D = 1 +�̄� . �̄�
𝑐, Ω =
1𝐷
𝑑𝑥𝑑𝑡
= �̄� + 𝑐2𝑞𝐷𝑑𝑞𝑑𝑡
= − [ ∇𝑐𝑐𝐷
+ 3
∑𝑖=1
𝑞𝑖 ∇𝑤𝑖] 𝑞 =�̄�
𝑐 + �̄� . �̄�
• Ray Path Equations:
SBPW3: sBOOM results 5
Run Parameters
5 January 2020
• All azimuthal angles run in parallel • Computing platform:
• OSX running macOS Mojave (10.14.6) • CPU: 2.5 GHz i7 • RAM: 16GB, 1600 MHz DDR3
• NASA Langley mid-range computing facility • Single node of SGI ICE Altix Cluster
• No pre-processing of near-field data • Computational run times
• Typical run times for edge-to-edge carpet predictions • ~30 seconds wall-time @ sampling frequency = 100 KHz (16 azimuths) • ~130 seconds wall-time @ sampling frequency = 200 KHz (16 azimuths)
• Sampling frequency determined by adjoint-error correction approach by continuously embedding uniformly refined grid
• 100 KHz sufficient to resolve loudness BSEL to within 0.1 dB • 400 KHz sufficient to resolve loudness BSEL to within 0.02 dB
SBPW3: sBOOM results 6
Case1: Ground Signatures
5 January 2020
SBPW3: sBOOM results 7
Case1: Loudness Metrics
5 January 2020
SBPW3: sBOOM results 8
Case2: Ground Signatures
5 January 2020
Measured Atmosphere
SBPW3: sBOOM results 9
Case2: Ground Signatures
5 January 2020
Standard Atmosphere
SBPW3: sBOOM results 9
Case2: Ground Signatures
5 January 2020
Standard Atmosphere
For the measured atmosphere, carpet widths are larger by:
• 28.17 nm on +ve side • 14.03 nm on –ve side
SBPW3: sBOOM results 10
Case2: Loudness Metrics
5 January 2020
SBPW3: sBOOM results 11
• = (1.4121, 0.015681, 0.000359) • Diffraction boundary layer thickness (𝜹) = 682.45m
(𝑀, �̇�, �̈�)Case1: Optional Focus Analysis
5 January 2020
Flight Altitude
𝜹-tangent ray
caustic-tangent ray
(𝑀, �̇�, �̈�)(𝑀𝑛, �̇�𝑛, �̈�𝑛)
caustic
SBPW3: sBOOM results 11
• = (1.4121, 0.015681, 0.000359) • Diffraction boundary layer thickness (𝜹) = 682.45m
(𝑀, �̇�, �̈�)Case1: Optional Focus Analysis
5 January 2020
Flight Altitude
𝜹-tangent ray
caustic-tangent ray
(𝑀, �̇�, �̈�)(𝑀𝑛, �̇�𝑛, �̈�𝑛)
Near-field (Given)
caustic
SBPW3: sBOOM results 11
• = (1.4121, 0.015681, 0.000359) • Diffraction boundary layer thickness (𝜹) = 682.45m
(𝑀, �̇�, �̈�)Case1: Optional Focus Analysis
5 January 2020
Flight Altitude
𝜹-tangent ray
caustic-tangent ray
(𝑀, �̇�, �̈�)(𝑀𝑛, �̇�𝑛, �̈�𝑛)
Near-field (Given)
𝜹
caustic
SBPW3: sBOOM results 11
• = (1.4121, 0.015681, 0.000359) • Diffraction boundary layer thickness (𝜹) = 682.45m
(𝑀, �̇�, �̈�)Case1: Optional Focus Analysis
5 January 2020
Flight Altitude
𝜹-tangent ray
caustic-tangent ray
(𝑀, �̇�, �̈�)(𝑀𝑛, �̇�𝑛, �̈�𝑛)
Near-field (Given)
𝜹
caustic
SBPW3: sBOOM results 11
• = (1.4121, 0.015681, 0.000359) • Diffraction boundary layer thickness (𝜹) = 682.45m
(𝑀, �̇�, �̈�)Case1: Optional Focus Analysis
5 January 2020
Flight Altitude
𝜹-tangent ray
caustic-tangent ray
(𝑀, �̇�, �̈�)(𝑀𝑛, �̇�𝑛, �̈�𝑛)
Computational domain of Lossy NTE
Near-field (Given)
𝜹
caustic
SBPW3: sBOOM results 12
Case1: Optional Focus Analysis
5 January 2020
𝜕2𝑃
𝜕�̄�2 − �̄�𝜕2𝑃𝜕𝜏2
+𝜇2
𝜕2𝑃 2
𝜕𝜏2+ [ 𝛼
𝜀2+ ∑
𝜈
𝜃𝜈 /𝜀2
1 + 𝜏𝜈𝜕 /𝜕𝜏 ] 𝜕3𝑃𝜕𝜏3
= 0
𝜇 = 2𝛽𝑃𝑎𝑐
𝜌0𝑐20 ( 𝑅𝑡𝑜𝑡𝑓𝑎𝑐
2𝑐0 )2/3
𝜀 = ( 2𝑐0
𝑅𝑡𝑜𝑡𝑓𝑎𝑐 )2/3
𝑅𝑡𝑜𝑡 ≈ 𝑅𝑐𝑎𝑢 =2𝛿3𝑓2
𝑎𝑐
𝑐20
Lossy NTE Model Equation as developed by Joe Salamone for the NASA Scamp Project
SBPW3: sBOOM results 12
Case1: Optional Focus Analysis
5 January 2020
𝜕2𝑃
𝜕�̄�2 − �̄�𝜕2𝑃𝜕𝜏2
+𝜇2
𝜕2𝑃 2
𝜕𝜏2+ [ 𝛼
𝜀2+ ∑
𝜈
𝜃𝜈 /𝜀2
1 + 𝜏𝜈𝜕 /𝜕𝜏 ] 𝜕3𝑃𝜕𝜏3
= 0
𝜇 = 2𝛽𝑃𝑎𝑐
𝜌0𝑐20 ( 𝑅𝑡𝑜𝑡𝑓𝑎𝑐
2𝑐0 )2/3
𝜀 = ( 2𝑐0
𝑅𝑡𝑜𝑡𝑓𝑎𝑐 )2/3
𝑅𝑡𝑜𝑡 ≈ 𝑅𝑐𝑎𝑢 =2𝛿3𝑓2
𝑎𝑐
𝑐20
Lossy NTE Model Equation as developed by Joe Salamone for the NASA Scamp Project
Incoming waveform
𝑃𝑎𝑐 = 50.05 Pa𝑓𝑎𝑐 = 6.32 Hz
SBPW3: sBOOM results 12
Case1: Optional Focus Analysis
5 January 2020
𝜕2𝑃
𝜕�̄�2 − �̄�𝜕2𝑃𝜕𝜏2
+𝜇2
𝜕2𝑃 2
𝜕𝜏2+ [ 𝛼
𝜀2+ ∑
𝜈
𝜃𝜈 /𝜀2
1 + 𝜏𝜈𝜕 /𝜕𝜏 ] 𝜕3𝑃𝜕𝜏3
= 0
𝜇 = 2𝛽𝑃𝑎𝑐
𝜌0𝑐20 ( 𝑅𝑡𝑜𝑡𝑓𝑎𝑐
2𝑐0 )2/3
𝜀 = ( 2𝑐0
𝑅𝑡𝑜𝑡𝑓𝑎𝑐 )2/3
𝑅𝑡𝑜𝑡 ≈ 𝑅𝑐𝑎𝑢 =2𝛿3𝑓2
𝑎𝑐
𝑐20
Lossy NTE Model Equation as developed by Joe Salamone for the NASA Scamp Project
Incoming waveform
𝑃𝑎𝑐 = 50.05 Pa𝑓𝑎𝑐 = 6.32 Hz
SBPW3: sBOOM results 12
Case1: Optional Focus Analysis
5 January 2020
𝜕2𝑃
𝜕�̄�2 − �̄�𝜕2𝑃𝜕𝜏2
+𝜇2
𝜕2𝑃 2
𝜕𝜏2+ [ 𝛼
𝜀2+ ∑
𝜈
𝜃𝜈 /𝜀2
1 + 𝜏𝜈𝜕 /𝜕𝜏 ] 𝜕3𝑃𝜕𝜏3
= 0
𝜇 = 2𝛽𝑃𝑎𝑐
𝜌0𝑐20 ( 𝑅𝑡𝑜𝑡𝑓𝑎𝑐
2𝑐0 )2/3
𝜀 = ( 2𝑐0
𝑅𝑡𝑜𝑡𝑓𝑎𝑐 )2/3
𝑅𝑡𝑜𝑡 ≈ 𝑅𝑐𝑎𝑢 =2𝛿3𝑓2
𝑎𝑐
𝑐20
Lossy NTE Model Equation as developed by Joe Salamone for the NASA Scamp Project
Incoming waveform
𝑃𝑎𝑐 = 50.05 Pa𝑓𝑎𝑐 = 6.32 Hz
SBPW3: sBOOM results 12
Case1: Optional Focus Analysis
5 January 2020
𝜕2𝑃
𝜕�̄�2 − �̄�𝜕2𝑃𝜕𝜏2
+𝜇2
𝜕2𝑃 2
𝜕𝜏2+ [ 𝛼
𝜀2+ ∑
𝜈
𝜃𝜈 /𝜀2
1 + 𝜏𝜈𝜕 /𝜕𝜏 ] 𝜕3𝑃𝜕𝜏3
= 0
𝜇 = 2𝛽𝑃𝑎𝑐
𝜌0𝑐20 ( 𝑅𝑡𝑜𝑡𝑓𝑎𝑐
2𝑐0 )2/3
𝜀 = ( 2𝑐0
𝑅𝑡𝑜𝑡𝑓𝑎𝑐 )2/3
𝑅𝑡𝑜𝑡 ≈ 𝑅𝑐𝑎𝑢 =2𝛿3𝑓2
𝑎𝑐
𝑐20
Lossy NTE Model Equation as developed by Joe Salamone for the NASA Scamp Project
Incoming waveform
𝑃𝑎𝑐 = 50.05 Pa𝑓𝑎𝑐 = 6.32 Hz
Zbar=0.0: PL = 97.8 dB
Zbar=0.05: PL = 106.8 dB
Zbar=1.0: PL = 101.0 dB
SBPW3: sBOOM results 13
Case1: Optional Focus Analysis
5 January 2020
SBPW3: sBOOM results 14
• Lossy vs Lossless propagation • Signature Evolution • Modeling Non-linearity • Loudness build-ups • Loudness Gradients
Highlights
5 January 2020
SBPW3: sBOOM results 15
Highlights: Lossless vs Lossy
5 January 2020
Phi = 00
SBPW3: sBOOM results 15
Highlights: Lossless vs Lossy
5 January 2020
Phi = 00Phi = -400
SBPW3: sBOOM results 15
Highlights: Lossless vs Lossy
5 January 2020
Phi = 00Phi = -400Phi = 400
SBPW3: sBOOM results 15
Highlights: Lossless vs Lossy
5 January 2020
Phi = 00Phi = -400Phi = 400
Losses account for significant (~10-12 dB) reduction in loudness metrics
SBPW3: sBOOM results 16
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Under-track
SBPW3: sBOOM results 16
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Under-track
SBPW3: sBOOM results 16
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Under-track
SBPW3: sBOOM results 16
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Under-track
Near-field character maintained over long
distances
SBPW3: sBOOM results 17
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Phi = 400
SBPW3: sBOOM results 17
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Phi = 400
SBPW3: sBOOM results 17
Highlights: Signature Evolution
5 January 2020
Scaling factor: 1𝑃
Vertical Distance from Cruise AltitudeAircraft Length
Phi = 400
SBPW3: sBOOM results 18
Highlights: Modeling Non-linearity
5 January 2020
Acoustic Potential formulation vs Poisson Implementation
SBPW3: sBOOM results 18
Highlights: Modeling Non-linearity
5 January 2020
Acoustic Potential formulation vs Poisson Implementation
“Numerical Simulation of Shock Wave Focusing at Fold Caustics, with application to Sonic Boom”, Marchiano, R., Coulouvrat, F., Grenon, R., JASA, 114, 1758 (2003), doI: 10.1121/1.1610459
SBPW3: sBOOM results 18
Highlights: Modeling Non-linearity
5 January 2020
Acoustic Potential formulation vs Poisson Implementation
“Numerical Simulation of Shock Wave Focusing at Fold Caustics, with application to Sonic Boom”, Marchiano, R., Coulouvrat, F., Grenon, R., JASA, 114, 1758 (2003), doI: 10.1121/1.1610459
Standard Atmosphere
SBPW3: sBOOM results 18
Highlights: Modeling Non-linearity
5 January 2020
Acoustic Potential formulation vs Poisson Implementation
“Numerical Simulation of Shock Wave Focusing at Fold Caustics, with application to Sonic Boom”, Marchiano, R., Coulouvrat, F., Grenon, R., JASA, 114, 1758 (2003), doI: 10.1121/1.1610459
Standard Atmosphere
SBPW3: sBOOM results 18
Highlights: Modeling Non-linearity
5 January 2020
Acoustic Potential formulation vs Poisson Implementation
“Numerical Simulation of Shock Wave Focusing at Fold Caustics, with application to Sonic Boom”, Marchiano, R., Coulouvrat, F., Grenon, R., JASA, 114, 1758 (2003), doI: 10.1121/1.1610459
Standard Atmosphere
SBPW3: sBOOM results 18
Highlights: Modeling Non-linearity
5 January 2020
Acoustic Potential formulation vs Poisson Implementation
“Numerical Simulation of Shock Wave Focusing at Fold Caustics, with application to Sonic Boom”, Marchiano, R., Coulouvrat, F., Grenon, R., JASA, 114, 1758 (2003), doI: 10.1121/1.1610459
Standard Atmosphere
As loudness levels get lower, significant impact of numerical implementation under windy conditions
SBPW3: sBOOM results 19
Highlights: Modeling Wind
5 January 2020
• Based on provided data, there is a large tailwind at the cruise altitude • Tailwind accounts for almost 10% of the speed of sound
SBPW3: sBOOM results 19
Highlights: Modeling Wind
5 January 2020
• Based on provided data, there is a large tailwind at the cruise altitude • Tailwind accounts for almost 10% of the speed of sound
Significant potential for input error
SBPW3: sBOOM results 20
Highlights: Loudness Build-up
5 January 2020
SBPW3: sBOOM results 20
Highlights: Loudness Build-up
5 January 2020
Loudness build-up plots show dominant portion to go after for OML shaping
SBPW3: sBOOM results 21
Highlights: Loudness Gradients
5 January 2020
SBPW3: sBOOM results 21
Highlights: Loudness Gradients
5 January 2020
SBPW3: sBOOM results 21
Highlights: Loudness Gradients
5 January 2020
SBPW3: sBOOM results 21
Highlights: Loudness Gradients
5 January 2020
Adjoint gradients provide a snapshot of what portions of the
near-field are important to minimize boom carpet loudness
SBPW3: sBOOM results 22
Summary• Near-field waveforms propagated using sBOOM • Lateral cut-off azimuths using standard atmospheres are usually quite different
from measured/realistic atmospheres • Lateral cut-off rays in realistic atmospheres can travel far • Could have low grazing angles
• Focus predictions show much higher loudness values than cruise booms (as expected)
• Different implementation of the underlying mechanisms seem to change the underlying characteristics of the ground signatures
• Poisson vs. Acoustic Potential solutions • Wind considerations • As loudness levels get lower, there is potential for numerical noise to
increase • Loudness build-up plots can localize the loudness dominating portions of the
signatures • Loudness gradients provide a snapshot to allow optimization of the OML
5 January 2020
SBPW3: sBOOM results 22
Summary• Near-field waveforms propagated using sBOOM • Lateral cut-off azimuths using standard atmospheres are usually quite different
from measured/realistic atmospheres • Lateral cut-off rays in realistic atmospheres can travel far • Could have low grazing angles
• Focus predictions show much higher loudness values than cruise booms (as expected)
• Different implementation of the underlying mechanisms seem to change the underlying characteristics of the ground signatures
• Poisson vs. Acoustic Potential solutions • Wind considerations • As loudness levels get lower, there is potential for numerical noise to
increase • Loudness build-up plots can localize the loudness dominating portions of the
signatures • Loudness gradients provide a snapshot to allow optimization of the OML
5 January 2020
SBPW3: sBOOM results 23
• NASA Commercial Supersonic Technology (CST) Project • Boom prediction workshop organizing committee
Acknowledgments
5 January 2020
SBPW3: sBOOM results 5 January 2020