Giornata di Studio sulle TURBOMACCHINE Bergamo – 15 luglio 2016 STUDIO NUMERICO – SPERIMENTALE DI TuRBomacchine di piccola potenza Rodolfo Bontempo Marcello Manna Raffaele Tuccillo Dipartimento di Ingegeria Industriale (D.I.I) Università di Napoli “Federico II”
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Giornata di Studio sulle TURBOMACCHINE
Bergamo – 15 luglio 2016
STUDIO NUMERICO – SPERIMENTALE
DI TuRBomacchine di piccola potenza
Rodolfo Bontempo Marcello Manna Raffaele Tuccillo
Dipartimento di Ingegeria Industriale (D.I.I)Università di Napoli “Federico II”
2
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
AbstractThe presentation deals with theoretical, numerical and experimental analysis of small sized turbomachines
• Ducted Rotors– The classical actuator disk model is improved to take into account all nonlinear flow features. It is
applied to the theoretical analysis and to the preliminary design of innovative devices like small ducted wind turbines.
• Turbochargers– The steady and unsteady behaviour of automotive turbochargers are studied my experimental
means. Some insights on the validity of the adiabatic flow assumption and on the statistical characterisation of the surge are provided.
– The analysis of turbochargers is further detailed showing the conceptual design of an innovative vaneless axial flow turbine.
– Finally, the design of a novel downstream volute for axial flow turbine is presented and discussed
• Radial flow turbine– A similarity criteria approach is used to investigate the actual possibilities of adopting a radial
flow turbine as an ORC expander. The results are validated by CFD.
• Bontempo, R., Manna, M., Solution of the flow over a non-uniform heavily loaded ducted actuator disk, Journal of Fluid Mechanics (728), pp. 163-195, 2013
• Bontempo, R., Manna, M., Performance analysis of open and ducted wind turbines, Applied Energy (136), pp. 405-416, 2014
• Bontempo, R., Manna, M., Effects of the duct thrust on the performance of ducted wind turbines, Energy (99), pp. 274-287, 2016
• Bontempo, R., Cardone, M., Manna, M., Vorraro, G., Steady and unsteady experimental analysis of a turbocharger for automotive applications, Energy Conversion and Management (99), pp. 72-80, 2015
• Cameretti M.C., Ferrara F., Gimelli A., and Tuccillo R., 2015, “Combined MGT – ORC solar –hybrid system. PART B: Component Analysis and Prime Mover Selection”, ENERGY PROCEDIA, vol. 81 (2015), pp. 379-389, doi: 10.1016/j.egypro.2015.12.107
• Cameretti M.C., Ferrara F., Gimelli A., and Tuccillo R., 2015, "Employing Micro-Turbine Components in Integrated Solar – MGT - ORC power plants", ASME paper GT2015-42572
• Conceptual design of an axial flow turbine for advanced variable geometry turbochargers, 2016 (A. Saccomanno Dissertation, Superv. R. Tuccillo, a. Pesiridis)
• Fluid-Dynamic Design of an Innovative Turbine-Volute Layout for Turbochargers, 2016 (A. Ferrara Dissertation, Superv. R. Tuccillo, a. Pesiridis)
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
References
• The nonlinear actuator disk method as applied toducted rotors
• UNINA Turbocharger Test Rig
• Conceptual design and analysis of a vaneless axial-flow turbine for turbochargers
• Design and analysis of axial flow turbine withdownstream volute for turbochargers
• Study of the ORC expander based on similaritycriteria and CFD analysis
4
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Summary
The nonlinear actuator disk method as applied to ducted rotors
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Ducted propellers Ducted Turbines
The duct improves the propulsive efficiencyThe duct prevents the occurrence of the cavitation
The duct improves the power coefficient �� (a ducted turbine can beat the Betz limit)
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
A semi-analytical and iterative procedurehas been developed
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
7
Main advantages of the method
• The method naturally takes into account the contraction of the wake (very important for ducted and heavily loaded propellers)
• The method duly accounts for the nonlinear and mutual interaction between the duct and the rotor ⟹ the rotor and duct flow fields are strongly coupled
• Non-uniform load distributions, rotor wake rotation and ducts of general shapes can be dealt with
• Low computational cost ⟹ it is well suited to be integrated in the first stage of design systems based on the repeated analysis scheme of hierarchical type
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Different Configurations
19 Stator Blades/20 Rotor Blades
39
MEAN
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Different Configurations19 Stator Blades/20 Rotor Blades
40
HUB
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
The design of diffuser and volutev Isentropic Flow v Free Vortex LawvMass conservation
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Cross Sections Calculation: Free Vortex Law
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
The concept of a symmetric volute
Use of two «semi-volutes» to reduce the clutter of the last sections and accomodate the radial flow exiting the diffuser
42
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Streamlines in the innovative volute
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
76,5
70,73
76,59 77,19 77,38 77,675
80
77
78,7 79,29 78,73 78,73
66
68
70
72
74
76
78
80
82
1 2 3 4 5 6
%
VOLUTES
System Efficiency
Total to Static Efficiency
Different configurations of the innovative volute
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Mesh Sensitivity of the ultimate systems
Innovative Volute System ElementsStator 105946Rotor 148990Diffuser 155678Volute 524670
Classic Volute System ElementsStator 107140Rotor 156942Diffuser 123270Volute 620345
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Performance MapsClassic Volute Innovative Volute
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
47
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
020000400006000080000
100000120000140000160000180000
1000 3000 5000 7000
Turb
ine
Spee
d [r
pm]
Data at Engine Speed [rpm]
Turbine with innovativevolute
Turbine with classicvolute
0
2
4
6
8
10
12
14
0 2000 4000 6000 8000
Turb
ine
Pow
er [k
W]
[rpm]Data at Engine Speed
Turbine with innovativevolute
Turbine with classic volute
11,11,21,31,41,51,61,71,81,9
2
0 2000 4000 6000 8000
Com
pres
sorP
ress
ure
Rat
io
[rpm]Data at Engine Speed
Turbine withinnovativevolute
Turbine withclassic volute
Turbine-Engine Matching
0
20
40
60
80
100
120
140
1000 2000 3000 4000 5000 6000 7000
Pow
er [k
W]
Engine speed [rpm]
Engine Power (Maximum Load)
Turbine withinnovativevoluteOriginal Turbine
160170180190200210220230240250260
1000 2000 3000 4000 5000 6000 7000To
rque
[Nm
]
Engine speed [rpm]
Engine Torque (Maximum Load)
Turbine with innovativevoluteOriginal Turbine
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Effect of Turbine-Engine Matching
THE DOWN-SIZED RADIAL TURBINE AS AN ORC EXPANDER
• The radial flow turbine from the well consolidated technology ofdown-sized turbochargers appears to be worthy of particularattention as an effective ORC expander
• An analysis to investigate the actual possibilities of adapting theradial flow turbine to a different application:
Ø Similarity criteriaØ CFD validation
• Working Fluids considered:• R245fa• (higher molecular mass compared with air and steam) • R134a • Ammonia (lighter working fluid )
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Reference conditions: Air expansion• Total-to-static pressure ratio
• Rotational speed
• Expected mass flow rate
50
1111
11 −−
+
−⋅
⋅
−−
=ORC
ORC
ref
ref
refref
ORC
ref
ORCORC
γγ
γ
γβ
ηη
γγ
β
ref
ORC
ef
ORC
ORC
refrefORC T
Tmm
SFN
N ⋅⋅=γ
γ)()(
ORC
ref
ORC
ref
ORC
ORC
ref
refORC
pp
refmm
TT
SFmm
γγ
⋅
⋅
=)()(
2&&
The changes in both rotational speed and mass flow rate are mainly governed bythe molecular mass of the new working fluid, while the turbine pressure ratiovaries in accordance with the isentropic exponent and the isentropic efficiency
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
Reference Conditionsvpressure ratio = 4.1 vangular speed = 20000 rad/s.
The ORC condensing pressure was estimated at 40 °C
The use of ammonia, even if more favourablein terms of cycle efficiency thanks to its higher superheating temperature, would imply an increase in rotor speed
51
Three dimensional views of theradial flow turbine rotor
refmm && /
Operating Conditions and Properties of the several working fluids
µ (Pa s) 2.62 x 10-5 1.54 x 10-5 1.91 x 10-5 2.56 x 10-5
ν (m2/s) 8.92 x 10-5 6.28 x 10-5 2.16 x 10-5 18.0 x 10-5
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
• Since the values of the mass flow delivered by the radial turbine shouldmeet those resulting from the energy balance of the heat recovery boilera further transformation has been also considered for this component byapplying an appropriate scaling factor (SF) according to the wellknown relationships:
52
222 ; 1 ; ORCORCORCORCORC
ORC
DHSF
Dm
DrefDSF
ωω ∝∆∝∝
=
&
For the T100-R245fa cases, a scaling factor of 1.525 was established
the C30-R134a case implied a reduction in mass flow rate that was obtained by applying a scaling factor of 0.592
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
53
• A simultaneous reduction of these parameters can be obtained by meansof an iterative procedure that leads to a decrease in the angular velocity(and, therefore, in the rotor flow capacity) and in the pressure ratio, inaccordance with the additional relationship:
−⋅⋅
−=∆
−γ
γ
βη
γγ
1
111
TRH
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
CFD analysis of the radial flow
turbine• The CFD analysis of the radial flow
rotor was carried out in a three-dimensional periodic sector of 40°with a tetrahedral mesh of 330000elements (with an average volume of1.89 x 10-2 mm3 and an average edgesize of 0.27 mm).
• Time marching solution of thetransonic flow
• Reynolds stress (7 eqs.) model for theviscous flow
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Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
55
Averaged meridional contours of relative Mach number
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
• A second step of this investigation was the off-design study that isdiscussed, as an example, for the C30-R245fa case that did not requireany adjustment in terms of scaling factor.
56
Characteristic curves of the radial flow rotor (Working fluid R245fa)
It is worth-noting that the rotor appears to cover a wide range of mass flow rates, even if acceptable values of the efficiency can be found in a more restricted interval
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
57Relative Mach number contours at mid-span (Working fluid R245fa)
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
58
The MICRO GAS TURBINE CAPSTONE C30
Ø Fossil and Biogas fuelling
Ø Matching with bottoming ORC
Giornata di Studio sulle Turbomacchine – Bergamo, 15 Luglio 2016
Bontempo, Manna, Tuccillo, D.I.I., Napoli Studio Numerico – Sperimentale di Turbomacchine di Piccola Potenza
• Micro Gas Turbine Laboratory,• Ce.S.M.A, Napoli, ITaly