DIPARTIMENTO DI ENERGIA

Recenti attività di ricerca applicata presso il Laboratorio di

Fluidodinamica delle Macchine (LFM)

Giornata di studio per le TurbomacchineBergamo 15 luglio2016

LFM presentation

Giacomo PersicoAssociate Prof.

Vincenzo DossenaFull Professor Berardo Paradiso

Assistant Prof.

Paolo GaetaniAssociate Prof.

Paolo GrigattiMeccanica

Alessandro Mora, Eng., PhDR&D, CFD, CAD/CAM

Andrea SpinelliAssistant Prof.

ACADEMIC STAFF

TECHNICAL STAFF

2 PhD students (Giacomo Gatti, Giorgia Cammi)

Crema Dario, EngMeccanica

1 research Fellow (Alberto Fusetti)

LFM : WHO WE ARE …. now 2

LFM presentation

LFM EXPERTISE IS TURBOMACHINERY• Aerodynamic measurements in high speed compressible

flows with own-developed and commercial techniques• CFD analysis of turbomachinery for R&D, design and

optimization, based on in house-developed and commercial tools

• Performance analysis of turbomachinery stages

Main Applications:

• Applied R&D for industry applications: Performance analysis of turbomachinery components. Radial & Axial machines. Turbines and Compressors.

Main industrial partners in the last 5 years: GE O&G, GE OGTL, AEN, FINCANTIERI, EDF, AVIO, Ferrari, …

R&D Granted By competitive funds (EU, IT, last 5 years) • ORC applications (Lombardia, EU-ERC NShock)• RECORD (EU-FP7 project on aero-acustics of jet engines)• PRIN (MIUR, performance of VAWT)

Main academic cooperation : (last 5 years)TU GRAZ, TU DELFT, VKI, DTU, DLR, UNI BS, UNI TN, UNI FI , UNI BG, ….

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LFM presentation

LFM FACILITIES OVERVIEW1. Pressurized air supply plant (6000 kg @ 20 MPa)

2. Calibration facility for steady state subsonic / supersonic directional probes and Hot Wires

3. LP shock tube for fast response probes unsteady calibration

4. Transonic/supersonic blow-down wind tunnels for linear cascades and large scale profiles

5. Low speed (LS) closed loop test rig for large scale annular cascades and axial turbines full stages (3000 rpm)

6. High Speed (HS) closed loop test rig for axial (400 kW – 20’000 rpm) and radial (800kW – 40’000 rpm) turbomachines stages

7. Test rig for organic vapours

8. Galleria del Vento for wind turbine tests

9. Hydraulic turbomachinery test plant

10. Safety relief valves test plant

11. Computational tools

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LFM presentation

2 & 3 - STEADY & UNSTEADY CALIBRATION OF DIRECTIONAL PROBES

Open jet calibration facility

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Mach number range up to 2.2

Angular range (yaw and pitch) ± 25 deg

Typical meas. uncertainty for directional probes

Yaw, pitch : ± 0.2 deg

Static pressure : 0.3 % of kinetic head

Total pressure : 0.2 % of kinetic head

shock tube

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LFM presentation

TRANSDUCER

Development of novel data reduction methodology for unsteady flows analysis (phase-resolved flow

field and turbulence level estimate)

2 & 3 - FAST RESPONSE AERODYNAMIC PROBES

• OWN DEVELOPED CYLINDRICAL AND SPHERICAL FAST RESPONSE PRESSURE PROBES FOR 2D AND 3D MEASUREMENTS (up to 80 kHz)

• Only 3 labs in Europe developed a similar technique• Max T ≈ 250 °C

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LFM presentation

2&3 - FAST RESPONSE MICRO THERMOCOUPLE

• Platinum / platinum rhodium: wire diameter : 25 m , freq. response up to 200 Hz, Mach < 0.6

• dimension and material as trade-off between robustness and promptness

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LFM presentation

4- Transonic and supersonic blow-down wind tunnel for LINEAR CASCADES

Main Partners: Nuovo Pignone (GE-O&G), ANSALDO, FINCANTIERI, ENEL, FTM, ABB,

• 2003-2007: FTM : Parametric analysis of the effects produced by the application of 3D design to low AR turbine blades

• 2008-2009: AEN : transonic 2D sections of LP steam turbine blades

• 2010-2012: Nuovo Pignone (GE-O&G): Development and selection of new profiles

• 2013-2014: Nuovo Pignone (GE-O&G): Re & Ra combined effect on profile performance

• 2015-2016: Fincantieri : supersonic profiles for high loaded steam turbines stages

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LFM presentation

• standard blade chord approx. 50 mm• Test section : blade height 50/80 mm x 400 mm (tang.)• Maximum flow rate : 8 kg/s ; Maximum inlet T = 60 °C• Reynolds number variation:

Standard condition : approx. ambient T and P at cascade outlet ( typical Re2 = 0.55 * 106; based on chord length = 50 mm, and Mach = 0.5 )

4- Transonic and supersonic blow-down wind tunnel for linear cascades

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Loss

Loss

Reynolds

LFM presentation

3D Flow Field Measurements In Straight / Annular Cascades

Definition Of A Prediction Model For 3d Design Including Leaning, Bowing And Sweep.

Detailed and Accurate Data for CFD Set-up and Validation

3D Design: bowing, leaning and sweepLoss and velocity vectors downstream of a

bowed turbine blade

4- CASCADES AERODYNAMICS

BOWING

LEANING

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LFM presentation

APPLICATION OF OPTICAL TECHNIQUES:

• PIV / LDV

• Oil flow visualization

Best efficiency operating conditionM2is = 1.18

Over- expanded nozzle. M2is = 1.03

114- CASCADES AERODYNAMICSSchlieren images to investigate

supersonic patterns

LFM presentation

5- LOW SPEED CLOSED LOOP TEST RIG FOR AXIAL TURBINE STAGES

• Large scale facility for axial turbine stages

• Detailed analysis of 3D flow-field

• High accuracy measurement of stage

efficiency over the stage operating range

• Easy and complete access for all

measurement techniques available at the LFM

(pneumatic, optical, etc.)

• Easy and economical parametrical analysis

(axial distance, tip clearance, etc.)

• Wide range of turbine geometries (up to 2

stages)

• Extremely accurate flow rate measurement

(< 0.5% unc.) and torque

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LFM presentationLFM presentation

5 - LOW SPEED TEST RIGa) Turbine Stage

b) Torque Sensor

c) Axial Compressor: 2 stages + IGV and VGVs

d) DC Motor: 80 kW, 3000 rpm

e) Centrifugal Blower: 500 kW, 20 m3/s, fan = 1.2, variable speed

f) Venturi Nozzle

g) Heat Exchanger

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- Rotating casing for azimuthal traverses

- Turbine on rolling bearings

- adjustable axial gap

- stator mounted on a rotating disk

- maximum diameter (tip): 900 mm

- minimum diameter (hub): 400 mm

- maximum blade height: 240 mm

- maximum number of stages: 2

Maximum expansion ratio 2.1: T = C * fan - loss

LFM presentation

5 – examples of investigations: steady measurements

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axial gap comparison

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LFM presentation

5 - Unsteady forcing by experiments

S1

Rotor

S2

s - P1

s – P2

From momentum conservation:

Axial Force Component

Tangential Force Component

EXP. CFD

∆ % ∆ % ∆ % ∆ %MinLoad 0.656 1.134 0.578 0.641

MaxLoad 0.638 0.744 0.451 0.559

EXP vs CFDPercentage Oscillations

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LFM presentation

5 - LOW SPEED TEST RIGOther rig applications

• Tests of large scale annular cascades

• A turbomachine component up to 4 m in length substitutes the axial group for aerodynamic tests

• 2014 , AEN tested a model of GT diffuser at several off design operation conditions: measurements by 5Hole probe, Hot Wire, Comparison with CFD

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CFD EXP

LFM presentation

6 - HIGH SPEED CLOSED LOOP TEST RIG FORAXIAL AND RADIAL TURBOMACHINES

Section Max rotational speed Max diameter Max. powerAxial turbine 20 000 rpm 400 mm 400 kW

Centrifugal compressor 40 000 rpm 560 mm 800 kW

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LFM presentation

6 – High Speed TEST RIG : BLADE ROWS INTERACTIONunsteady effects due to: wakes, sec. flows, shocks, rows clocking effects, axial gap, etc

LFM FOCUS ON : 1) 3-D INTERACTION IN HP TURBINE STAGES, AXIAL GAP EFFECTS

2) VANED DIFFUSER-IMPELLER UNSTEADY INTERACTION IN CENTRIFUGAL COMPR.

Example 1 : Phase resolved flow field downstream of the turbine rotorRELATIVE TOTAL PRESSURE FIELD

by FRAPP measurements

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Example 2 : Phase resolved flow field downstream of the compressor rotor

STATIC PRESSURE FIELDby FRAPP measurements

LFM presentation

6 - HS TEST RIG : CORENOISE REDUCTION IN AEROENGINES(2013 – 2015) FP7 : RECORD - Research on COrenoiseReDuction, (industrial partners: AVIO, TURBOMECA,

SNECMA, RRD, RRUK, ITP, ecc.)

LFM CONTRIBUTION 1) Provide turbine unsteady flow field at different operating

point to support unsteady numerical simulations for noise radiation and propagation

2) Experimental simulation of turbine-combustor aero-acoustic interaction: characterization of temperature (entropy) and pressure disturbances at turbine inlet and their effects on the turbine aerodynamics and aero-acoustics.

Prex. Pattern

Temp. pattern

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LFM presentation

6 - Impact of the expansion ratio: Op. Conditions 20

Outlet flow angle

OP Flow rate (kg/s)

Rpm Expansion ratio ( Total to Static )

Inlet temperature (K)

OP4 2.45 4150 1.15 303OP3 3.78 7000 1.4 323OP2 4.9 9000 1.65 323OP1 6.05 11100 1.95 323

Streamwise Vorticity ( s ) and loss cores ( Y )

• I : tip passage vortex• II: shed vortex• III: corner vortex• IV: hub passage vortex

sin,T

Tin,TPPPP

Y

STATOR OUTLET FLOW-FIELDOP1: transonic condition

LFM presentation

Rotor Incidence angle

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OP1: transonic condition

OP4: subsonic condition

6 - Impact of the expansion ratio: ROTOR OUTLET

WAKE and SECONDARY FLOWS intensify

LFM presentation

Entropy: Wake evolution - CFD

6 - Stator - Rotor interaction

EXPCPT,R map downstream of the rotor evolution for OP1 (rotor frame of ref.)

Vortex filaments have similar, although more complex,

behaviour

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LFM presentation

6 - Efficiency and lossesStator losses

Span-wise pattern from secondary flow + casing boundary layer lower for higher

expansion ratios (Mach, Reynolds)

OP βTS Y %OP1 1.95 5.79OP2 1.65 5.77OP3 1.4 5.93OP4 1.155 6.62

Total to static efficiencyby real work and expansion ratio

OP βTS TS TT Y %OP1 1.95 0.819 0.906 5.79OP2 1.65 0.814 0.896 5.77OP3 1.4 0.79 0.864 5.93OP4 1.15 0.767 0.837 6.62

Span-wise pattern from rotor secondary + tip clearance flows higher efficiency for higher expansion ratios (Mach, Reynolds, rotor incidence + interaction)

Compressibility impact: direct (M, Re on the stator/ rotor)indirect (incidence and interaction)

TS ≈ 5%

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LFM presentation

7 -TROVA: a Test Rig for Organic Vapours ( inter- dept lab. CREA)• Unique test bench in the world for measurements in streams of organic vapours.

• Originally requested (2009) and designed together with

• Granted by Regione Lombardia in 2012 and EU-ERC Nshock (2014)

• Next congress ORC -2017 organisation MDM

H20

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LFM presentation

7 - TROVA: a Test Rig for Organic VApoursDifferent expansion ratio and different inlet thermodynamicconditions dense gas effects can be tested

Detailed analysis by pressure taps and Schlieren on a nozzle;comparison with CFD

AB C

CBA

= 6Pin = 3.15 barATTin = 246 °C

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LFM presentation

11 - CFD skills and capabilities

zTurbo ; c-COMPREX Preliminary calculation tool for selection and 0 D design Coupled with optimization algorithms for preliminary optimization

TzFlow Throughflow calculation of multistage turbomachinery Valid for any kind of architecture CFD-based axisymmetric model, without limitations in flow regime Combined with evolutionary algorithms for optimization of meridional

surface (i.e., spanwise evolution of velocity triangles)

3D, steady or unsteady CFD models (Ansys, Openfoam) Analysis computational model for advanced studies Successful validation with in-house experiments Unsteady stator-rotor calculation models sliding mesh

well captured flow physics computed efficiency within 1% of experimental one

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DEEP INTERACTION WITH EXPERIMENTAL ACTIVITY: Experimental data to validate computational set-up is a key tool CFD provides a powerful tool for analysis and interpretation of

experimental measurements

LFM presentation

11 - Automatic design tool for turbomachinery blades Shape Optimization to minimize OF (η) playing with the geometry

Stochastic Evolutionary strategy (GA) only direct CFD is required

Surrogate-based methodology to tackle costs (≈ 15 h)

Both Training and Trust-region formulations available

Constrained formulation to match flow rate / structural resistance

Robust multi-point formulation to include off-design optimization

Application to a supersonic converging-diverging cascade: 40% reduction of loss in design conditions up to 60% reduction of loss in off-design conditions

Baseline Optimized

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LFM presentation

8 - EXPERIMENTAL RESEARCH ON VAWT• Several experimental campaigns on VAWT inside the «GALLERIA DEL VENTO di

BOVISA» 2 test sections :• 4m x 4m : max wind speed 45 m/s• 14m x 4m:max wind speed 14 m/s

• Performance curve (Cp vs. λ)• Phase resolved flow field downstream of

the turbine for performance analysis and CFD validation

• Academic and industrial partners (UniTn, DTU and RISO Copenhagen, Tozzi Nord, etc.)

• Measurements by 5HP, HW, Power

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LFM presentation

8 - Experimental research onVAWTExamples of results

Turbine power curve

DeepWind Turbine wake for upright and 15° tilted rotor

H-shaped turbine

Wake flow fieldTSR = 3.9

TSR = 1.5

TSR = 2.4 - experimental results

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LFM presentation

GRAZIE per

L’ ATTENZIONE

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LFM presentation

Some bibliography on cascades aerodynamics

• INCIDENCE ANGLE AND PITCH-CORD EFFECTS ON SECONDARY FLOWS DOWNSTREAM OF A TURBINE CASCADE”, ASME Journal of Turbomachinery, 1993

• TURBULENCE MEASUREMENTS DOWNSTREAM OF A TURBINE CASCADE AT DIFFERENT INCIDENCE ANGLES AND PITCH-CHORD RATIOS”, ASME paper 93

• ON TESTING THE AERODYNAMICS OF FILM-COOLED BLADES, 1996 • THE INFLUENCE OF ENDWALL CONTOURING ON THE PERFORMANCE OF A TURBINE NOZZLE

GUIDE VANE”, J. Turbomach. -- April 1999 • STAGGER ANGLE AND PITCH-CHORD RATIO EFFECTS ON SECONDARY FLOWS DOWNSTREAM

OF A TURBINE CASCADE AT SEVERAL OFF-DESIGN CONDITIONS”, ASME Paper GT 2004 – 54083• ON THE EFFECTS OF LEANING AND BOWING TECHNIQUES ON TURBINE CASCADES FLOW

FIELD:EXPERIMENTAL AND NUMERICAL ANALYSIS”, 2004• PARAMETRICAL ANALYSIS ON THE EFFECTS PRODUCED BY LEANING AND BOWING

TECHNIQUES ON TURBINE CASCADES FLOW FIELD”, ETC 2007• ON THE APPLICATION OF LEANING TECHNIQUE ON ANNULAR TURBINE CASCADES,

ISROMAC12-2008• ON THE DEFINITION OF THE SECONDARY FLOW IN THREE-DIMENSIONAL CASCADES, 2009, I

MECH E Journal of Power and Energy• THE INFLUENCE OF BLADE LEAN ON STRAIGHT AND ANNULAR TURBINE CASCADE FLOW

FIELD”, ASME Journal of Turbomachinery, January 2011• THE INFLUENCE OF BLADE SWEEP TECHNIQUE IN LINEAR CASCADE CONFIGURATION, ASME

Paper GT2011• OPTIMIZATION OF A HIGH-PRESSURE STEAM TURBINE STAGE FOR A WIDE FLOW COEFFICIENT

RANGE . ASME Turbo Expo 2012. ; • THE INFLUENCE OF ROUGHNESS ON A HIGH-PRESSURE STEAM TURBINE STAGE: AN

EXPERIMENTAL AND NUMERICAL STUDY”J. Eng. Gas Turbines Power. 20, JANUARY 2015

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LFM presentation

SOME BIBLIOGRAPHY ON UNSTEADY AERODYNAMICS IN TURBINE AND COMPRESORS

“INVESTIGATION OF THE FLOW FIELD IN A HP TURBINE STAGE FOR TWO STATOR-ROTOR AXIAL GAPS: PART I – 3D TIME-AVERAGED FLOW FIELD”, Journal of Turbomachinery, 2007

“INVESTIGATION OF THE FLOW FIELD IN A HP TURBINE STAGE FOR TWO STATOR-ROTOR AXIAL GAPS: PART II – UNSTEADY FLOW FIELD”, Journal of Turbomachinery, 2007

“INFLUENCE OF ROTOR LOADING ON THE UNSTEADY FLOWFIELD DOWNSTREAM OF A HP TURBINE STAGE”, European Turbomachinery Conference, 2007

“A PARAMETRIC STUDY OF THE BLADE ROW INTERACTION IN A HIGH PRESSURE TURBINE STAGE”, ASME Journal of Turbomachinery, 2009

“BLADE ROW INTERACTION IN A ONE AND A HALF STAGE TRANSONIC TURBINE FOCUSING ON THREE DIMENSIONAL EFFECTS: PART II – CLOCKING EFFECTS” , Journal of Turbomachinery, 2009

“THREE DIMENSIONAL CLOCKING EFFECTS IN A ONE AND A HALF STAGE TRANSONIC TURBINE”, Journal of Turbomachinery, 2010.

“EFFECTS OF AXIAL GAP ON THE VANE-ROTOR INTERACTION IN A LOW ASPECT RATIO TURBINE STAGE”, AIAA Journal of Propulsion and Power, 2010.

• “ANALYSIS OF THE IMPELLER - VANED DIFFUSER INTERACTION IN A CENTRIFUGAL COMPRESSOR BY MEANS OF AN AERODYNAMIC FAST RESPONSE PROBE”, European Turbomachinery Conference, 2011

• “UNSTEADY AERODYNAMICS OF A LOW ASPECT RATIO TURBINE STAGE: MODELING ISSUES AND FLOW PHYSICS”, Journal of Turbomachinery, 2012.

• “IMPELLER-VANED DIFFUSER INTERACTION IN A CENTRIFUGAL COMPRESSOR AT OFF DESIGN CONDITIONS”, Journal of Turbomachinery, 2012

• “IMPELLER-VANED DIFFUSER INTERACTION IN A CENTRIFUGAL COMPRESSOR AT THE BEST EFFICIENCY POINT”, ASME GT Paper, 2012

• “ENTROPY WAVE GENERATOR FOR INDIRECT COMBUSTION NOISE EXPERIMENTS IN A HIGH-PRESSURE TURBINE”, European Turbomachinery Conference, 2015

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LFM presentation

“A Novel Package for Turbomachinery Throughflow Analysis”, 2011, Proceedings of the 9th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics

“A penalty formulation for the throughflow modeling of turbomachinery”, 2012, Computers & Fluids

“Unsteady Aerodynamics of a Low Aspect Ratio Turbine Stage: Modeling Issues and Flow Physics”, 2012, ASME Journal of Turbomachinery

“Optimization of Turbomachinery Flow Surfaces Applying a CFD-based ThroughflowMethod”, 2013, ASME Journal of Turbomachinery

“Preliminary Design of a Centrifugal Turbine for Organic Rankine Cycle applications”, 2013, ASME Journal of Engineering for Gas Turbines and Power

“Centrifugal Turbines for Mini-Organic Rankine Cycle Power Systems”, 2014, ASME Journal of Engineering for Gas Turbines and Power

“Adjoint Method for Shape Optimization in Real-Gas Flow Applications”, 2014, ASME Journal of Engineering for Gas Turbines and Power

“Aerodynamics of Centrifugal Turbine Cascades”, 2015, ASME Journal of Engineering for Gas Turbines and Power

“Automatic Design of ORC Turbine Profiles Using Evolutionary Algorithms”, 2015, Proceedings of the Third International Seminar on ORC Power Systems

CFD & OPTIMIZATION : Selected Publications 33

LFM presentation

"Aerodynamic Measurements on a Vertical Axis Wind Turbine in a Large Scale Wind Tunnel", 2011, ASME Journal of Energy Resources Technology,

"An Experimental Study of the Aerodynamics and Performance of a Vertical AxisWind Turbine in a Confined and Non-Confined Environment", 2015, ASME Journal of Energy Resources Technology,

, "Three-Dimensional Character of VAWT Wakes: an Experimental Investigation for H-shaped and Troposkien Architectures; 2016, asme IGTI GT2016-57762

LFM@Polimi: Journal publications on VAWT 34