Industrial fan design and investigation by means of URANS ... - Cineca

FMGroup @ DIMA-SUR 

Industrial fan design and investigation by means of 

URANS and LES based numerical methods 

Alessandro CORSINI, Giovanni DELIBRA 


www.dima.uniroma1.it 



giovanni.delibra@uniroma1.it 

CINECA - Bologna, 27 Nov. 2012

WHO’S WHO @ FluidMachinery Group, DIMA-SUR 

Marco Bassetti 

Domenico Borello 

Lucio Cardillo 

Alessandro Corsini 

Giovanni Delibra 

Andrea Marchegiani 

Previous CFD team members (… now in industry) 

Carlo Iossa 

Filippo Menichini 

Stefano Minotti 

Andrea Santoriello 





Franco Rispoli 

Giuseppe Riccucci 

Rafael Saavedra @ UDEP Piura, Peru 

Fabrizio Sciulli 

Esmeralda Tuccimei 

Paolo Venturini 

CFD software 

FEM f90 & C++ Xenios 

FVM f90 T-Flows 

FVM OpenFOAM 



WHAT ARE WE DOING w.r.t. CFD 

URANS, LES and hybrid LES/RANS for heat and mass transfer & combustion 

Particle Tracking, Fouling and Deposition 

development and assessment of new models & numerical technologies 

computations of industrial flows, mainly for turbomachinery applications 

Partner Industries 

Faggiolati Pumps 

FlaktWoods Group 

Fieni Srl 





Industrial flows computed with OpenFOAM 

• Axial flow fans: 

• control of separation 

• operations under strong pressure fluctuations 

New projects 

• Large centrifugal fans: rotor-stator interaction 

• LES of onshore caisson for Wells Turbine with Actuator Line Methodology 


Outline 

Most of these projects were run on CINECA or CASPUR [*] HPC grids 




[*] CASPUR is now part of CINECA 



Up‐front logic for CFD oriented design, 

where is to be located? 

at conceptual stage to provide hints of the basic 

governing flow physics 

e.g. biomimesis 

at preliminary stage to explore possbile flow 

configuration to exploit the selected physical 

mechanisms 

at the detailed design stage to elaborate the 

range of virtual proto‐types 

cost reduction in the R&D process 

less “real” proto‐types and test‐rigs 

larger set of explored design solutions available since the 

early stage of the process 

design solution oriented by a deeper knowledge of the 

underlying flow physics 

not just empiricism 




from D. Jakipse, 2001 


AXIAL FLOW FAN FOR TUNNEL AND METRO UNITS 

with 

FlaktWoods Group 







Problem to solve 

Industrial fans for tunnels in metropolitan mass-transfer systems: 

•need to comply with new EU legal requirements that pose strict efficiency and 

acoustic emission limits; 

•need to be able to adapt to complex operating conditions such as: 

• smoke and hot (400°C) gas extraction in case of fire 

• the destabilising effects of compression and expansion pressure waves 

generated by the passage of the trains inside the tunnels 

•need to increase pressure rise and blade loading because of market request 





























• stall control is a key technology for axial fan operations 





• need to increase pressure rise and blade loading because of market request 

• stall control is a key technology for axial fan operations 

• one of the possible source of inspiration for new stall resistant solutions 

comes from biomimesis 

• Biomimesis is the examination of nature, its models, systems, processes, and 

elements to emulate or take inspiration from in order to solve human problems. 


Problem to solve: possible ways to solve it 

• Possible solution to design stall resistant fan blades: exploiting the peculiar shape 

of the leading edge of the flippers of the humpback whale 






How flipper tubercles make a mercyless hunter 

exploiting the shape of the leading edge of the flippers of the humpback whale 

Corsini, A., Delibra, G., Sheard, A.G., “On the role of leading-edge bumps in the control of stall on-set in axial fan blades”, Proceedings of the FAN 2012 Conference, Senlis, France, 2012. 

main objective of the work was to scrutinise the performance of a sinusoidal leading 

edge on a cambered airfoil (NACA4415); comparison with symmetric profile 

(NACA0015) was provided 

influence of the leading edge geometry at different operating conditions was studied 

assessment of a modified sinusoidal-shaped leading edge in terms of lift and drag 

performance 





lift coefficient shows that the introduction of a sinusoidal-shaped leading 

edge modifies the aerofoil performance during stall: 

• early recovering in the aerodynamic work capability 

• 30% gain in lift after stall for the WHALE4415 cambered airfoil 




Lift coefficient vs Angle of Attack 







the leading edge geometry directly impacted on the aerofoil velocity and 

vorticity fields: 

• leading edge sinusoid peak > stabilising effect at the trailing edge 

• leading edge sinusoid through > separation 




separation 

Pressure isolines on the suction surface 

NACA4415 




JFM 224 

Blade section ARA-D 

Diameter at the tip 2240 mm 

Blade count 16 

Hub-to-tip ratio 0.5 

hub tip 

Chord (mm) 143 92.5 

Solidity (-) 0.64 0.21 

Pitch angle (deg) 48 24 

Volume Flow Rate 150 m 3 /s 

Total Pressure Rise 2800 Pa 

Rotation speed 1500 rpm 

Energy consumption 0.5 MW 

Reynolds number, based on D tip and V tip exceeds 26M 

A stator is present downstream the rotor but it is not 

accounted for in the simulations. 

Equations are always solved in the relative frame of 

reference, accounting for Coriolis and centrifugal forces 





solver SRFSimpleFOAM 

(more or less) 

approach RANS 


Numerical methodology 

model non-linear (cubic) low-Re k- (Lien et al.) 

cell count 4.1M (2M hexa + 2.1M tetra) 

average y + 1.2 (blade), 1.9 (hub & casing) 

domain 1 blade vane, extending 1c upstream and 

2c downstream the rotor 

numerical 

schemes 

CDS (momentum) 

QUICK (turbulent variables) 

solver GAMG (pressure) 

CG (other eqns) 

tolerance: 10 -10 

operating 

points 

110, 130 and 150 m 3 /s 






When the whale hits the fan 

Design of a “whale fan” based on literature and data from 

isolated airfoil 

Sinusoidal profile limited to the tip of the blade 

Hub was not “whaled” 

• The sinusoid amplitude was chosen as 3% of the chord at tip 

• The wavelength as 5% of the blade span 

• 5.5 sinusoids were used, starting with a peak at the tip 





Q [m 3 /s] Total pressure rise [Pa] 

Exp JFM224 JWFM224 

 

(datum) (whale fan) 

110 2858 +1% 2831 2748 -3% 


Validation of results 

130 2752 +2% 2798 2714 -3% 

150 2511 +2% 2565 2502 -2% 






Inner working of the bumps 

Corsini, A., Delibra, G., Sheard, A.G., “LEADING EDGE BUMPS IN VENTILATION FANS”, GT2013-94853 submitted to ASME Turbo Expo 2013, San Antonio (US) 

Pressure isolines on the suction surface of the blade for the investigated cases 








whale 

For JFM224 isolines are aligned with the leading edge of 

the blade and the only distortion comes from the tip, due 

to leakage from the pressure surface. 

In JWFM224 low pressure cores are generated at the 

trough of the sinusoid, as already occurred with an 

isolated profile. 








The low-pressure cores are responsible for the release 

from the leading edge of counter-rotating turbulent 

structures 

The straight blade of JFM224 does not generate any 

large-scale structure apart from the tip-leakage vortex. 

Such vortex in J1 case interacts with a large separation 

zone at the tip of the blade. 







streamlines at 95% of the blade span 

In W1 the structure originates at the leading edge is 

counter-rotating with respect to the leakage vortex and 

partially blocks its evolution. This lead to a complete 

reattachment of the flow on the suction surface 

streamlines at 95% of the blade span 







turbulent structures, visualised with an iso-surface of the vorticity 




















solver modified version of pisoFOAM 

(to account for Coriolis and centrifugal effects) 

approach LES 

model one equation (k) for SGS (Davidson) 

cell count 9M hexa 

average y + 1.2 (blade), 1.9 (hub&casing) 

domain 1 blade vane, extending 1c upstream and 1c 

downstream the rotor 

numerical 

schemes 


CDS (momentum) 

QUICK (turbulent variables) 

solver GAMG (pressure) and CG (other eqns) 

tolerance: 10 -10 

operating 

point 

150 m 3 /s 

Numerical methodology 





Inflow average velocity components 

p ±1000 Pa 

Ubulk ±4.8% 

tramp 1.3x10-5 s 

tpulse 4 ms 

Pressure increase/drop characterisation 


Simulation of pressure pulses 





A B C 


Evolution of c p for compression wave 

A: beginning of compression 

B: middle 

C: end of compression tip 

D. Borello - A. Corsini – G. Delibra – F. Rispoli – A. G. Sheard., “Numerical Investigation On The 

Aerodynamics Of A Tunnel Ventilation Fan During Pressure Pulses”, submitted to ETC 2013 

mid 

hub 




• sudden change of the pressure 

distribution during the pulse (B) 

• capability of the rotor to adapt to 

quickly the new mass flow rate 

(C) 

• pressure isolines on the suction 

surface show a clear 90 deg 

turning (B) 

• during pressure pulse (B) isolines 

are more radial and give 

evidence of a stall from the hub 

to 2/3 of the span, while the tip 

section is still capable of 

contributing to the rotor pressure 

developing capability. 


A: beginning of expansion 

B: middle 

C: end of compression 

A B C 


Evolution of c p for expansion wave 

D. Borello - A. Corsini – G. Delibra – F. Rispoli – A. G. Sheard., “Numerical Investigation On The 

Aerodynamics Of A Tunnel Ventilation Fan During Pressure Pulses”, submitted to ETC 2013 

tip 

mid 

hub 




• As the pulse hits the blade (B) the 

rotor adjust to the drop of mass 

flow increasing the work and so 

the lift over the blade 

• In this case the distribution of 

pressure isolines remains 

“vertical”, yet a strong load of the 

tip of the blade is recognisable 

• Distributions of the pressure 

coefficient show that midspan and 

tip sections are over-loaded 


Evolution of blade loading during pressure pulse 

time evolution of the integral values of forces 

on the blade during the increase (top) or 

drop (bottom) of mass flow rate 

Compression wave: 

D. Borello - A. Corsini – G. Delibra – F. Rispoli – A. G. Sheard., “Numerical 

Investigation On The Aerodynamics Of A Tunnel Ventilation Fan During 

Pressure Pulses”, submitted to ETC 2013 


as the blade stalls, the peripheral component 

of force is almost null, whereas the axial 

component shows a sudden change of sign 

Expansion wave: 

overall overload of the blade, as the value of 

both axial and peripheral forces doubles 






Next 

more snow 

more whales 

more fans (lot of fun) 

and something new… 





LES of a Oscillating Water Column device coupled with Wells turbine for 

Mediterranean operations simulated with Actuator Line Methodology (CINECA, 

IscraB) 

Numerical tools: hasNotANameYetFoam 


A glimpse of the future (i) 

Blade profile (rotor) NACA0015 

Dtip 500 mm 

Dhub 375 mm 

OWC chamber 

Solidity 0.64 

Wells turbine 

Blade count 7+2x 

3600 rpm 

U bulk (axial): 9.1 m/s 





Numerical computations of the performance of Technopal centrifugal fan (FlaktWoods 

Group), with particle dispersion, deposit and erosion 

Numerical tools: pimpleDyMFoam (for URANS, possibly hybrid LES/RANS) 

pTrack (in-house FEM code for particle tracking, erosion and fouling) 

Technopal fan assembly 


A glimpse of the future (ii) 

Impeller inlet diameter 1804 mm 

Impeller outlet diameter 3440 mm 

Volute outlet diameter 5600 mm 

Impeller blade width 400 mm 

Volute width 200 mm 

Impeller blade count 11 

Rotational frequency 900 rpm 




Technopal impeller rendering 



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Industrial fan design and investigation by means of URANS ... - Cineca

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