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InVIGO - take ortex ngestion in round perations
Unsteady simulation of intake ground vortex ingestion in real wind tunnel
conditions
R. Mendonça e Costa, G. Millot, S. Raynal, (Altran) J.P. Bouchet, S. Courtine (CSTB)
12.04.2021
FP103-Aero2020-mendonca
1.Introduction
1. InVIGO and ground vortex
Project description
3 Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
INVIGO project
Intake Vortex Ingestion in Ground Operations
▪ EU project within H2020 CleanSky2 program (Engine Integrated Technology
Demonstrator) (10/2019 → 01/2022)
▪ Two main actors :
▪ ALTRAN (Fluids and Thermal, Toulouse): Project Coordinator, CFD, Data
Analytics
▪ CSTB (Jules Verne WT, Nantes): Wind Tunnel campaigns
▪ Project supervised by EU and SAFRAN Aircraft Engines (Topic Leader)
▪ Key outcomes
▪ Methods able to predict ground vortex characteristics from reduced
instrumentation using data science approach
▪ Ground vortex measurement campaign(s) with both detailed and reduced
instrumentation
▪ CFD numerical simulations of ground vortex
Yadlin & Shmilovich, 2006
1. Introduction
4
Vortex formation
Wind direction
Wind velocity
Engine vibrations; suction of abrasive particles
Inlet air speed
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
2.Computational Domain and generated grids
2. Computational domain and generated grids
6
Reference geometry: Jules Verne Climatic Wind Tunnel (WT), CSTB, Nantes
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
1/6.5 scale nacelle with test mock-up
Vertically moving table for nacelle
ground clearance adjustment
Glass area for Stereo-PIV acquisition
CSTB Jules Verne WT
2. Computational domain and generated grids
7
WT configuration Isolated configuration
WT configuration (top); isolated
configuration (bottom)
Setup Grid size (elements)
Isolated configuration 47 M
WT configuration 57 MMax. Cell size [m]
BOI nacelle lips 𝟐. 𝟒𝟏 × 𝟏𝟎−𝟑
BOI inlet 𝟒. 𝟖𝟑 × 𝟏𝟎−𝟑
BOI ground region vortex
vicinity
𝟔. 𝟒𝟒 × 𝟏𝟎−𝟑
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
3.Problem formulation and numerical setup
3. Problem formulation
9
Steady simulations
RANS + 𝑘𝜔 − 𝑆𝑆𝑇 for closure
Unsteady simulations
SAS (Scale Adaptive Simulations)1
Verification of characteristic time and length scales:
• Vortex length (Kolmogorov) scales > grid size in vortex vicinity
→ grid resolution OK
• Range of time scales of interest determined
→ appropriate timestep selection for unsteady calculation
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
• Need for characterizing ground vortex on many ground clearance, wind speed, intake velocity combinations.
• Numerical simulations showed that steady simulations were not efficient for some challenging cases.
• Steady and Unsteady simulations have to be considered.
1F.R. Menter, Y. Egorov: The Scale−Adaptive Simulation Method
for Unsteady Turbulent Flow Predictions. Part 1:
Theory and Model Description (2010)
3. Numerical setup: boundary conditions
10
WT configuration Isolated configuration
Velocity-inlet
condition: 90° wind
velocity, 10 m/s
crosswind
Pressure-outlet
condition: ambient, non
disturbed conditions
Pressure-outlet condition: target Mass Flow rate (10 kg/s),
followed by pressure specificationUnsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
Height to inlet
diameter ratio (H/D):
0.85
U*=𝑼𝒊/𝑼𝒘𝒊𝒏𝒅: 8.5
3. Numerical setup: convergence verification
11
WT configuration
Isolated configuration
Both configurations (WT and
isolated) tested at identical
intake mass flow rate
(difference within 1%)
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
Total pressure distribution (relative to undisturbed pressure) on the reference fan
plane for the WT (top) and isolated (bottom) configuration. Solution at flow time of
0.79s.
4.Results
4.1 Results: comparison between isolated and WT configurations
13
WT
co
nfi
gu
rati
on
Iso
late
dc
on
figu
ratio
n
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
Both configurations (WT and
isolated) display similar path
lines, namely in vortex
vicinity
Vortex related
phenomena can be
safely analysed in a
simplified/isolated
configuration: little to
no influence from
experimental setup for
this operating point
Path lines (coloured by velocity magnitude) entering the reference fan plane. Solution at flow time of 0.79s
4.2 Post-processing strategies: distortion index to locate vortex
centre
14
How to determine:
• 1), 2) vortex centre (radial and azimuthal
coordinates)
• 3), 4) vortex radius and 𝑉𝜃
1, 2
3, 4
Vortex centre
determination
based on
distortion
indexes
𝑫𝑪𝜽 =𝑷𝒇 − 𝑷𝜽
𝒒𝒇
𝑰𝑫𝑪 = 𝐦𝐚𝐱𝒓∈[𝟎;𝒓𝒎𝒂𝒙]
𝑷𝒕,𝒓 − 𝑷𝒕,𝒓𝒎𝒊𝒏
𝑷𝒕
Vortex centre
coordinates determined
at the end of the steady
simulation
How to ensure vortex tracking
throughout the unsteady simulation?
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
4.3 Vortex tracking: Q-criterion iso-clips
15
• Define a circular region centred on the pre-determined vortex centre,
quasi-tangent to the extremity of the reference fan plane.
• Set 10 Q-criterion iso-clips on the defined circular region, with different
minimum and maximum threshold:
Q-criterion iso-clip
minimum threshold [s-1]
Q-criterion iso-clip
maximum threshold [s-1]
1 × 103 6 × 1012
1 × 104 6 × 1012
1 × 105 6 × 1012
2 × 105 6 × 1012
5 × 105 6 × 1012
1 × 106 6 × 1012
2 × 106 6 × 1012
5 × 106 6 × 1012
1 × 107 6 × 1012
2 × 107 6 × 1012
captures the entire vortex
and its immediate vicinity
captures the vortex core
Iso-clip
decreasing
in areaReference fan plane Q-criterion distributions taken
at equal intervals up to 0.1965s of flow time.
Circular region enclosing the vortex highlighted in
white.
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
4.4 Vortex monitoring: Q-criterion iso-clips
16
On the 10 Q-criterion iso-clips 𝒄 = 𝒄𝟏, 𝒄𝟐, … , 𝒄𝟏𝟎 monitor the following
variables throughout the unsteady simulation:
• Area of each clip;
• Circulation Γ on each clip (computed as the surface integral of the
vorticity component perpendicular to each reference plane
• Area-weighted average coordinates of each one of the iso-clips
𝑟𝑒𝑞 𝑐, 𝑡 =𝐴𝑐𝑙𝑖𝑝𝜋
𝑉𝜃(𝑐, 𝑡) =Γ
2𝜋𝑟𝑒𝑞(𝑐, 𝑡)
𝑟𝑣𝑜𝑟𝑡𝑒𝑥 𝑐𝑒𝑛𝑡𝑟𝑒 = 𝑓 𝑐, 𝑡𝜃𝑣𝑜𝑟𝑡𝑒𝑥 𝑐𝑒𝑛𝑡𝑟𝑒 = 𝑓(𝑐, 𝑡)
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
4.5 Vortex monitoring: Q-criterion iso-clips
17
For a given instant in time, 𝒕 = 𝒕𝟏, equivalent vortex radius 𝑟𝑒𝑞 and 𝑉𝜃 can be determined
using the information from all the retrieved iso-clips 𝒄 = 𝒄𝟏, 𝒄𝟐, … , 𝒄𝟏𝟎 :
The maximum of the curve 𝑽𝜽 = 𝒇(𝒓𝒆𝒒) yields the vortex radius
and 𝑉𝜃 corresponding to a given instant 𝑡 = 𝑡1.
The average coordinates of the smallest iso-clip (capturing
vortex core only) will yield an accurate estimation of
𝒓𝒗𝒐𝒓𝒕𝒆𝒙 𝒄𝒆𝒏𝒕𝒓𝒆 = 𝒇 𝒕 and 𝜽𝒗𝒐𝒓𝒕𝒆𝒙 𝒄𝒆𝒏𝒕𝒓𝒆 = 𝒇(𝒕)
Performing this exercise for all instants 𝑡 of the simulation, one can obtain 𝒓𝒆𝒒 = f(t) and 𝑽𝜽 = f(t)
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
4.6 Vortex monitoring: Q-criterion iso-clips
18
The variables of interest appear
to be in fair agreement for both
studied setups (isolated nacelle
and WT configuration).
Significant oscillations observed
in the evolution of variables over
time, for both configurations:
deeper analysis of the devised
tracking methodology.
Can the biggest Q-
criterion iso-clips
(lower threshold)
capture additional
structures in vortex
vicinity?
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
Q-criterion distribution (log scale) on the reference fan plane;
representation of lowest threshold Q-criterion iso-clip.
5.Conclusion and future work
5. Conclusion and future work
20
• Comparison between the unsteady
simulation of ground vortex formation and
ingestion in two different configurations:
isolated nacelle vs. WT;
• No major differences in terms of vortex
phenomena between both setups → little to
no influence from the geometry/elements in
the experimental facility, for this operating
point;
• Automated determination of vortex centre
for a given steady solution;
• Tracking of vortex centre coordinates,
vortex radius and 𝑉𝜃 over the course of an
unsteady simulation.
Milestones achieved Future work
• Improvement of the tracking strategy for
unsteady simulations: detection of Q-
criterion iso-contours from the vortex centre
and moving outwards → compute
circulation Γ along each contour;
• Retrieve data from reference planes (fan,
PIV) periodically for a posteriori analysis;
• Construction and assimilation
of an experimental database
of velocity fields and pressure
measurements scanning a
wide range of H/D and U *
parameters
Unsteady simulation of intake ground vortex ingestion in real wind tunnel conditions – Mendonça e Costa et al. – 3AF 2020 +1
5 m/s
10 m/s
15 m/s
20 m/s
Adapted from M. Jermy and W.H. Ho: Location of the vortex
formation threshold at suction inlets near ground planes by computational fluid
dynamics simulation (2008)
Acknowledgements : European Union, Safran Aircraft EnginesThe InVIGO project has received funding from the Clean Sky 2 Joint Undertaking under the European
Union’s Horizon 2020 research and innovation programme under grant agreement No 864288
This communication and the data provided here represent only the authors’ view and do not engage Clean
Sky 2 nor the European Union for any use that may be made of the information they contain.
Thank you for your attention
Contacts : [email protected], [email protected],