Computational Fluid Dynamics Engineering Simulation

1
Computational Fluid Dynamics Engineering
Simulation

• Professor Peter Stow
• RR Engineering Fellow Computational Fluid
  Dynamics
• Head of Aerothermal Methods
• Rolls Royce plc

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Design Considerations
Aerodynamics
Heat Transfer
Manufacture
Stress Level
Component Geometry
Vibration
Material
Weight
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Computer Aided Engineering
CFD MODELS
STRESS VIBRATION MODELS

• AERODYNAMIC
• THERMODYNAMIC
• DESIGN

TEST
MECHANICAL DESIGN ANALYSIS
MANUFACTURE
PRODUCT
CAD
MANUFACTURING PROCESS MODELS
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High Performance Computing Potential Impact

• Reduced engineering analysis time cost
• more automated analysis
• more integrated analysis
• Improved accuracy of engineering analysis
• more accurate numerical model
• more accurate mathematical model of physical
  processes
• achieved at acceptable cost
• achieved in acceptable elapsed time
• Advances in computers mean that this is becoming
  possible

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CFD Applications
Combustion
Nacelle


aerodynamics
Two-Phase Combusting flow

crosswind effects

external aerodynamics

installed engine/pylon/wing interaction


fuel injector
and combuster
cooling flows
Fan
Exhaust

aerodynamics

afterbody flow

fan flutter

nozzle, mixer, jet flow

fan/OGV/pylon interaction

IGV forced response

Turbine

multistage aerodynamics

aero design and optimisation

end wall and blade heat transfer

film cooling
Compressor

rotor shroud leakage

Multistage aerodynamics


unsteady rotor/stator flow
rim seals
Engine Systems

annulus leakage flow

unsteady vane/rotor flow

rotating disc cavity flows


brush and labyrinth seals
forced response

secondary air system losses
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Swept Fan Aerodynamics
Leading edge
Shock (more radial)
Flow
Conventional Fan
Swept Fan
Mn rel
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Fan Flutter - Issues
Acoustic Liners
Fan Flutter 5 Margin required (before
threats) 3 Stability Margin (after stack-up) No
Flutter post Bird-strike
Tip leakage Treatment
Downstream Acoustics
L/E Shape Erosion
Downstream Non-axisymmetric issues (pylon,
reverser etc.)
Fan blade shape - Aerodynamics - Untwist -
Modeshape
Intake - Acoustics - Inlet Distortion -
Non-axisymmetry
Fan Internal Disk - Mistuning - Damping
Engine-to-engine Variability
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Fan Flutter

• Steady Viscous Flow
• Unsteady Linearised Flow
• Vibration Modeshape from SC03

unstable
Steady
stable
Surface Work
SC03 Mode
Unsteady
Aerodynamic Damping
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Fan-OGV-Pylon Design
Static Pressure
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Fan-OGV-Pylon Design
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Fan-BOGV-Pylon Interaction
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Fan-BOGV-ESS Interaction
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MULTISTAGE ANALYSIS
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Unsteady Rotor-Stator Interaction
Contours of Vorticity
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3D Rotor-Stator Interaction
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Turbine Forced Response
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Turbine Forced Response
Original Wake P0
Wake Shaping
Shaped Wake P0
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Engine Intake Analysis
Installed Nacelle
Ground Plane Effects
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Horizontal Cross Section Windward Lip
Horizontal Cross Section Windward Lip
25 Knot Forward Speed 35 Knot
Crosswind Non-Dimensional Mass Flow 2307 (full
scale) Freestream P 380kPa T 298K Driving
P 292kPa
25 Knot Forward Speed 35 Knot
Crosswind Non-Dimensional Mass Flow 2312 (full
scale) Freestream P 380kPa T 298K Driving
P 294kPa
25 Knot Forward Speed 35 Knot Crosswind
Windward Lip Separation
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Fan Face Plane
Fan Face Plane
25 Knot Forward Speed 35 Knot
Crosswind Non-Dimensional Mass Flow 2307 (full
scale) Freestream P 380kPa T 298K Driving
P 292kPa
25 Knot Forward Speed 35 Knot
Crosswind Non-Dimensional Mass Flow 2312 (full
scale) Freestream P 380kPa T 298K Driving
P 294kPa
25 Knot Forward Speed 35 Knot Crosswind
Windward Lip Separation
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Engine Intake Analysis
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Installed Nacelle Analysis
Flow Solution on Aircraft Surface - Fuselage,
Wing, Nacelles and Pylons - Half Model
Installed Nacelle Analysis 1,930,378 Tetrahedral
Cells 316,303 Points 91,316 Boundary
Faces Inviscid Flow Solution Pictures Visual3
Solution on Chordwise Cut through Inboard Nacelle
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Traditional 3D Design by Analysis
Analyse Prepare next 3D CFD run Submit o/night
run Wait for results
Original Design
2-D design tools Cloning stacking
1st Design
Analyse Prepare next CFD run Submit o/night
run Wait for results
nth Design
2nd Design
Continue sequence
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FAITH Design System
Automatic creation of perturbations and CFD
submission for overnight runs
Seven Perturbations
No Communications
No Communications
No Communications
No Communications
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FAITH - 3D Forward Linear Design
Linear Design
Linear Design
Check linear design with overnight CFD run
Linear Design
Original Design
2nd Re-design ( nth design in current process)
Interactive day-time analysis
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FAITH - 3D Inverse Linear Design
Original
Target
User defined target flow field
Check linear design with overnight CFD run
Linear Design
2nd Re-design ( nth design in current process)
Original Design
Interactive day-time analysis No need to iterate
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Non-Axisymmetric Endwalls
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Application Areas(Whole Engine Modelling)
Aerodynamic Requirements Performance Efficiency
(SFC) Surge Margin Noise
Manufacturing Processes and Cost
Weight
Shape Optimisation
Life
Aeroelasticity Force Response Flutter
Heat-transfer Cooling
Mechanical Requirements Maximum Stress F.O.D.
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Rolls-Royce SOPHY Design System

• PADRAM-HYDRA-SOFT Aerodynamic Design System
• Advance Parametric design system R-R business
  application focus
• Turbomachinery blading
• Fan BOGV - pylon
• Intakes
• By-pass Exhaust nozzle afterbody
• Fan tone noise, Fan-BOGV noise
• Water-jet pump
• Direct links to CAD system(s) - Parametric
  representation
• Rapid automatic meshing structured,
  unstructured, mixed grids
• State of the art versatile Optimisation system
  for design capability

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Integrated Automatic Design Optimisation System
SOPHY SOFT-PADRAM-HYDRA
SOFT
New design
Base design
PADRAM
Yes
Additional design parameters/cost
OK?
jm52
No
Design parameters
Optimizer
jm56
Cost constraints
Design Review
HYDRA
Optimum design
Automation Flowchart

• Geometry created meshed parametrically
• CFD boundary conditions and mesh pre-processed
  in batch
• Costs and constraints extracted in batch
• Library of optimisers available

Convergence history
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Current Design System
Nacelle/ Intake
OGV pre-diffuser
LPC System
Nozzle design
PADRAM HYDRA SOFT
Casing treatment
Non axi- endwalls
Exhaust nozzle
Multi-stage design
Forced response
Water pump
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Nacelle Automation and Optimisation
SOFT
GEMO
Design Parameters
RAMIN (Mesh)
mesh (RAMIN)
cost and constraint functions
JM52
HYDRA
JL09-PAX
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Nacelle/Intake Design Space

• The Design parameters 77 parameters
• Intake Scarf Angle
• Intake Centreline Angle (relative to engine
  centreline)
• ..
• Secondary geometric parameters
• Internal Lip Tilt (angle between intake C/L and
  local lip axis topline, sideline and bottom line)
• Non-planer Highlight

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RAMIN Rapid Meshing for Intakes/Nozzles
RAMIN Mesh on Symmetry Plane
HYDRA solution
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New Design Capability
Parametric Collector box
Low noise fan and OGV design
PADRAM HYDRA SOFT
Automatic design of Casing treatment
General Endwall design capability
Parametric Exhaust Nozzle System
Internal cooling passages
Under platform Cavity Well design
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High Performance Computing Potential - New
Simulations

• Cheaper/more affordable computing offers vast
  prospects for new
• simulations
• Multistage Analysis - Steady/Unsteady CFD
• Component optimisation over whole operating range
  
• Whole engine optimisation
• Aeroelasticity - CFD lt-gt Stress/Vibration
  analysis
• Component optimisation for performance
  structural integrity
• Noise Analysis - Unsteady CFD
• Design optimisation for Noise as well Performance
  Stability
• Turbine Heat Transfer -CFDlt-gtHeat
  Conductionlt-gtStress Analysis
• Performance life optimisation
• Multi-disciplinary Optimisation
• CFDlt-gtStructural Analysislt-gtManufacturing
• Turbulence Transition modelling
• Direct/Large Eddy Simulation

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Turbulence TransitionDNS LES
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Tone Noise Sources and Propagation
Rotor AloneNon-LinearSteady
Bypass3D Bypass Liner/Geometry Optimisation
Distortion NoiseFull 3D Non-linearUnsteady
RadiationIntake Liners Intake Geometry
Buzz-SawFull Annulus Non-Linear
Fan/OGVOGV Geometry Fan/OGV Ratio
Radiation and Transmission Thru Shear Layer
LP TurbineMulti-stageUnsteady
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Broadband Noise Sources
Fan Wake/OGV Interaction
OGV Self Noise
Rotor BBSelf-Noise Interaction with Inlet B.L.
Jet Noise
Fan-OGV BB Sources due to turbulence interacting
with (blade) surfaces Jet Noise due to Turbulence
(and shocks)
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Low Tone Noise Fan Blade Design
Design space covered axial and circumferential
movement (lean sweep) of blade sections over
outer 20 of blade span (4 design parameters)
HYDRA, PADRAM and SOFT used to demonstrate low
tone noise fan blade design optimisation
Cost Function (Pa)
datum cost
9dB reduction
Design Iterations
Each iteration around 2 hours on PC cluster
initial optimum achieved in 2 days
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Low Tone Noise Fan Blade Design
Design optimisation introduces forward sweep of
blade sections over outer 20 of span - leads to
swallowed shock at tip compared to expelled shock
of datum blade
Low tone noise blade
Datum fan blade
95 span
95 span
contours of static pressure
contours of static pressure
75 span
75 span
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Hydra QTD Buzz-Saw Analysis
26 blade full annulus
Measured Static Stagger Angle Variation Hydra
CFD mesh 55M nodes Run time per aerodynamic
point (96 cluster CPUs) 10 days Viscous end
walls Rotor tip gap included Acoustic Liner
included
Acoustic Liner
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Broadband Jet Noise
Exhaust Nozzle LES
Plane Jet DNS Far-field Noise by Acoustic Analogy
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Computational Fluid Dynamics Engineering
Simulation

• Professor Peter Stow
• RR Engineering Fellow Computational Fluid
  Dynamics
• Head of Aerothermal Methods
• Rolls Royce plc