Computational Aero Accoustics Analysis of the Broadband Engine Noise SImulator Experiment

46 Pages·2015·55.4 MB·English

Computational Aero-Acoustics Analysis of the
Broadband Engine Noise Simulator Experiment

(presented at 21st AIAA/CEAS Aeroacoustics Conference, Dallas, TX)
Christoph Brehm
Science and Technology Corporation

Jeffrey Housman, Cetin C. Kiris
Applied Modeling and Simulation Branch
NASA Ames Research Center

Florence Hutcheson
Aero-acoustic Branch
NASA Langley Research Center

Funded by the NASA Fundamental Aeronautics Program Environmentally
Responsible Aviation (ERA) Project
20th of August, 2015, AMS Seminar Series, NASA Ames Research Center
Outline
•  Introduction to BENS Aero-Acoustic Analysis
•  Computational Simulation Strategy and Setup
•  Characterization of Flow Field in Source Region
•  Noise Source Identification
–  Causality Method
–  Proper Orthogonal Decomposition (paper only)
•  Linear Acoustic Analysis
–  Acoustic Model of FJID
–  BENS Scattering Results
•  Conclusions/Outlook
2
Outline
•  Introduction to BENS Aero-Acoustic Analysis
•  Computational Simulation Strategy and Setup
•  Characterization of Flow Field in Source Region
•  Noise Source Identification
–  Causality Method
Part 1:
fundamental noise
–  Proper Orthogonal Decomposition (paper only)
source analysis
•  Linear Acoustic Analysis
Part 2:
–  Acoustic Model of FJID
applied linear
acoustic analysis
–  BENS Scattering Results
•  Conclusions/Outlook
3
Outline
•  Introduction to BENS Aero-Acoustic Analysis
•  Computational Simulation Strategy and Setup
•  Characterization of Flow Field in Source Region
•  Noise Source Identification
•  Linear Acoustic Analysis
–  Acoustic Model of FJID
–  BENS Scattering Results
•  Conclusions/Outlook
4
Introduction
The airplane forebody is intended to
o  Advantage of HWB/BWB is potential to shield noise by main body
shield the fan and turbomachinery
noise radiating forward from the engine
Note: This work focuses on The incident
inlet, while aft turbomachinery and jet
broadband component of field can be generated directly by the
noise shielding would be found by
turbomachinery noise FSC using simple sources (monopoles,
moving the engine nacelles forward of
dipoles, and/or quadrupoles), or it can
the t railing edge. Twin vertical tails (or
be created externally using other noise
“vert icals”) would be used to shield to
prediction codes.
the s ide of the flight path. For quieter

cont rol surfaces, slats are replaced by look at Tinetti how he models
The test matrix may include different
droo ped leading edges, and flaps are taken from Tinetti & Dunn, AIAA-2012 broadband noise; subdivides octave
flight speeds and
repla ced by trailing edge elevons. band into 49 bins and super-imposes
angles of attack; high lift system o  Large test matrix for different flight conditions and airplane configurations
with random phases
settings; landing gear component
epi ted in Fig 6. T e loca io and numb r o  Use equivalent source method to solve 3D Helmholtz equation in
deployment; acoustic source type
of sour es en ur s that an as mmetric frequency domain (fast turn-around times) è Linear Acoustic Analysis
(broadband fan
general purpose coust c ield of suff
and/or jet noise simulators); nacelle o  Incident pressure field can be generated by using analytic source
cient st engt wi l be gener The FSC uses the equivalent source
type, number and placement; and distribution (monopoles, dipoles, and/or quadrupoles)
method (ESM) to solve an exterior
inclusion of liner technology. Physically
three-dimensional Helmholtz
o  Use CFD solver to develop simplified acoustic model (or sample on
accurate computational tools can be
boundary value problem (BVP) by
permeable surface) è LES of Nonlinear Source Region
used to evaluate the potential noise
expanding the scattered acoustic
shielding benefits associated with any o  Improved understanding of noise generation process guides the pressure field into a series of point

given development of acoustic model è Noise Source Identification
epi ted in Fig 6. T e loca io and numb r 5 sources

configuration, thus helping the test
of sour es en ur s that an as mmetric distributed on a fictitious surface
engineer tailor the matrix to include
general purpose coust c ield of suff placed inside the actual scatterer.
only the most promising combinations.
cient st engt wi l be gener
Overview of BENS CAA Strategy
Objective: Develop fully predictive BENS-CAA capability
1.) High fidelity CFD simulation of FJID & 5.) Engine placement study is performed
development of linear acoustic model using experiment and CAA
Four Jet Impingement Device
(FJID) used as broadband
noise source
2.) BENS experiment by
Small
 Wedge

Hutcheson et. al. [2014]
3 FJID are placed
inside engine to
emulate broadband
1
  4.) Comparison of BENS acoustic model with
2
  noise component Large
 Wedge

experimental data from Hutcheson et al. [2014]
3

experiment
BENS
3.) Linear acoustic Analysis of BENS
experiment using FJID model
field sensor
locations
6
Launch Ascent & Vehicle Aerodynamics (LAVA) Framework
LAVA is being developed at NASA Ames Research Center
Unstructured Arbitrary Overset Structured
Cartesian AMR
Polyhedral Curvilinear
o  Essentially no manual grid generation
o  Grid generation is mostly o  High quality, body fitted
o  Highly efficient Adaptive Mesh
automated grids
Refinement (AMR)
o  Body fitted grids o  Low computational cost
o  Low computational cost
o  Grid quality can be o  Reliable higher order
o  Reliable higher order methods are
questionable methods are available
available
o  High computational cost o  Grid generation is largely
o  Non-body fitted -> Resolution of
o  Higher order methods are yet manual and time
boundary layers problematic/
to fully mature consuming
inefficient
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*Kiris et al.(2014), Sozer et al. (2014), Brehm et al. (2014)
Outline
•  Introduction to BENS Aero-Acoustic Analysis
•  Computational Simulation Strategy and Setup
•  Characterization of Flow Field in Source Region
•  Noise Source Identification
•  Linear Acoustic Analysis
–  Acoustic Model of FJID
–  BENS Scattering Results
•  Conclusions/Outlook
8
Precursor Simulation
Precursor simulation to obtain FJID
Mach Number Contours and Sonic Line
nozzle exit conditions
L
p
Ÿ
m
L
p
L
p
o  Precursor simulation with LAVA-Unstructured Nozzle Exit Boundary Conditions
(assuming symmetry)
o  Match mass-flow rate in experiment

o  Use averaged pipe length, L
p
o  Extract boundary conditions at the nozzle exit
o  Reference conditions are based on mean
exit conditions: p =1atm, V =335.8 m/s, and
ref ref
T =235.3K, Re=75,000
ref
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FJID Simulation Setup
Four-Jet-Impingement Device (FJID) High Frequency Sampling on Planes
x-y
y-z
x-z
o  Higher-order shock capturing scheme: modified ZWENO5/6
o  4th-order explicit Runge-Kutta time-integration with Δt defined through CFL≈0.5

o  Implicit large eddy simulation based on previous experience with jet
impingement problem

o  Immersed boundary method (no wall modeling approach employed)
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