alessandro corsini, giovanni delibra · comes from biomimesis • biomimesis is the examination of...

FMGroup @ DIMA-SUR

Industrial fan design and investigation by means of URANS and LES based numerical methods

[email protected] - Bologna, 27 Nov. 2012

Alessandro CORSINI, Giovanni DELIBRA


FMGroup @ DIMA-SUR

www.dima.uniroma1.it

FMGroup @ DIMA-SUR



WHO’S WHO @ FluidMachinery Group, DIMA-SUR

Previous CFD team members (… now in industry)Carlo IossaFilippo MenichiniStefano MinottiAndrea Santoriello

CFD software

FEM f90 & C++ XeniosFVM f90 T-FlowsFVM OpenFOAM

Marco BassettiDomenico BorelloLucio CardilloAlessandro CorsiniGiovanni DelibraAndrea Marchegiani

Franco RispoliGiuseppe RiccucciRafael Saavedra @ UDEP Piura, PeruFabrizio SciulliEsmeralda TuccimeiPaolo Venturini

FMGroup @ DIMA-SUR



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 PumpsFlaktWoods GroupFieni Srl

FMGroup @ DIMA-SUR



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

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

[*]CASPUR is now part of CINECA

Outline

FMGroup @ DIMA-SUR



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‐typescost 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

FMGroup @ DIMA-SUR



AXIAL FLOW FAN FOR TUNNEL AND METRO UNITSwith

FlaktWoods Group

FMGroup @ DIMA-SUR



Industrial fans for tunnels in metropolitan mass-transfer systems:

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

Problem to solve

FMGroup @ DIMA-SUR








•need to increase pressure rise and blade loading because of market request• stall control is a key technology for axial fan operations

Problem to solve

FMGroup @ DIMA-SUR



• 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, andelements to emulate or take inspiration from in order to solve human problems.

• Possible solution to design stall resistant fan blades: exploiting the peculiar shapeof the leading edge of the flippers of the humpback whale

Problem to solve: possible ways to solve it

FMGroup @ DIMA-SUR



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

How flipper tubercles make a mercyless hunter

main objective of the work was to scrutinise the performance of a sinusoidal leadingedge 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 dragperformance

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.

FMGroup @ DIMA-SUR



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


FMGroup @ DIMA-SUR



the leading edge geometry directly impacted on the aerofoil velocity andvorticity fields:

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


separation

Pressure isolines on the suction surfaceNACA4415


FMGroup @ DIMA-SUR



JFM 224Blade section ARA-D

Diameter at the tip 2240 mmBlade count 16

Hub-to-tip ratio 0.5hub tip

Chord (mm) 143 92.5Solidity (-) 0.64 0.21

Pitch angle (deg) 48 24Volume Flow Rate 150 m3/s

Total Pressure Rise 2800 PaRotation speed 1500 rpm

Energy consumption 0.5 MW

Reynolds number, based on Dtip and Vtip exceeds 26M

A stator is present downstream the rotor but it is notaccounted for in the simulations.

Equations are always solved in the relative frame ofreference, accounting for Coriolis and centrifugal forces

FMGroup @ DIMA-SUR



Numerical methodology

solver SRFSimpleFOAM(more or less)

approach RANSmodel 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 rotornumericalschemes

CDS (momentum)QUICK (turbulent variables)

solver GAMG (pressure)CG (other eqns)tolerance: 10-10

operatingpoints

110, 130 and 150 m3/s

FMGroup @ DIMA-SUR



When the whale hits the fan

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

FMGroup @ DIMA-SUR



Q [m3/s] Total pressure rise [Pa]

Exp JFM224(datum)

JWFM224(whale fan)

110 2858 +1% 2831 2748 -3%

130 2752 +2% 2798 2714 -3%

150 2511 +2% 2565 2502 -2%

Validation of results

FMGroup @ DIMA-SUR



Inner working of the bumps

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

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

FMGroup @ DIMA-SUR




whaleFor JFM224 isolines are aligned with the leading edge ofthe blade and the only distortion comes from the tip, dueto leakage from the pressure surface.

In JWFM224 low pressure cores are generated at thetrough of the sinusoid, as already occurred with anisolated profile.


FMGroup @ DIMA-SUR




The low-pressure cores are responsible for the releasefrom the leading edge of counter-rotating turbulentstructures

The straight blade of JFM224 does not generate anylarge-scale structure apart from the tip-leakage vortex.Such vortex in J1 case interacts with a large separationzone at the tip of the blade.


FMGroup @ DIMA-SUR




In W1 the structure originates at the leading edge iscounter-rotating with respect to the leakage vortex andpartially blocks its evolution. This lead to a completereattachment of the flow on the suction surface

streamlines at 95% of the blade span

streamlines at 95% of the blade span

FMGroup @ DIMA-SUR



Inner working of the bumpsturbulent structures, visualised with an iso-surface of the vorticity


FMGroup @ DIMA-SUR








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

Problem to solve

FMGroup @ DIMA-SUR



solver modified version of pisoFOAM(to account for Coriolis and centrifugal effects)

approach LESmodel one equation (k) for SGS (Davidson)cell count 9M hexaaverage y+ 1.2 (blade), 1.9 (hub&casing)domain 1 blade vane, extending 1c upstream and 1c

downstream the rotornumericalschemes

CDS (momentum)QUICK (turbulent variables)

solver GAMG (pressure) and CG (other eqns)tolerance: 10-10

operatingpoint

150 m3/s

Numerical methodology

FMGroup @ DIMA-SUR



p ±1000 PaUbulk ±4.8%tramp 1.3x10-5 stpulse 4 ms

Inflow average velocity components

Simulation of pressure pulses

Pressure increase/drop characterisation

FMGroup @ DIMA-SUR



A B C

• sudden change of the pressuredistribution during the pulse (B)

• capability of the rotor to adapt toquickly the new mass flow rate(C)

• pressure isolines on the suctionsurface show a clear 90 degturning (B)

• during pressure pulse (B) isolinesare more radial and giveevidence of a stall from the hubto 2/3 of the span, while the tipsection is still capable ofcontributing to the rotor pressuredeveloping capability.

Evolution of cp for compression waveA: beginning of compressionB: middleC: end of compression tip

mid

hub

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

FMGroup @ DIMA-SUR



tip

mid

hub

A B C

A: beginning of expansionB: middleC: end of compression

• As the pulse hits the blade (B) therotor adjust to the drop of massflow increasing the work and sothe lift over the blade

• In this case the distribution ofpressure isolines remains“vertical”, yet a strong load of thetip of the blade is recognisable

• Distributions of the pressurecoefficient show that midspan andtip sections are over-loaded

Evolution of cp for expansion wave


FMGroup @ DIMA-SUR



Evolution of blade loading during pressure pulsetime evolution of the integral values of forceson the blade during the increase (top) ordrop (bottom) of mass flow rate Compression wave:

as the blade stalls, the peripheral componentof force is almost null, whereas the axialcomponent shows a sudden change of sign

Expansion wave:

overall overload of the blade, as the value ofboth axial and peripheral forces doubles


FMGroup @ DIMA-SUR



Next

more snowmore whales

more fans (lot of fun)and something new…

FMGroup @ DIMA-SUR



LES of a Oscillating Water Column device coupled with Wells turbine forMediterranean operations simulated with Actuator Line Methodology (CINECA,IscraB)

Numerical tools: hasNotANameYetFoam

A glimpse of the future (i)

OWC chamber Wells turbine

Blade profile (rotor) NACA0015Dtip 500 mmDhub 375 mmSolidity 0.64Blade count 7 + 2x 3600 rpmUbulk (axial): 9.1 m/s

FMGroup @ DIMA-SUR



Numerical computations of the performance of Technopal centrifugal fan (FlaktWoodsGroup), 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)

A glimpse of the future (ii)

Impeller inlet diameter 1804 mmImpeller outlet diameter 3440 mmVolute outlet diameter 5600 mmImpeller blade width 400 mmVolute width 200 mmImpeller blade count 11Rotational frequency 900 rpm

Technopal fan assembly Technopal impeller rendering

FMGroup @ DIMA-SUR



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alessandro corsini, giovanni delibra · comes from biomimesis • biomimesis is the examination of...

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