UNIVERSITY OF ROME

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UNIVERSITY OF ROME LA SAPIENZA
Department of Mechanics and Aeronautics
DESIGN OF A NANO-GAS TURBINE Thermal and
Structural Analysis
Pace Francesco
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Why nanoturbine?

• Displacement of human activities
• Increased use of mobile and stand alone devices

Need to provide energy in discontinuos, efficient
and serviceable way

• Applications
• military use (powering of equipment, aeronautic
  propulsion, etc.)
• electro-medical equipment
• telecommunication

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Nanoturbine
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Hypothesis and Experience
DESIGN
Definition of Performance
Tecnological know-how
Flow,Thermal and Structural Equations
Numerical Simulation and Test
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Before my work
Explanation of Mechanical, Thermal and Kinematic
Characteristics
Preliminary Design of Impeller and Stator of
Compressor
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Before my work

• Radial and single-stage Turbine and Compressor to
  limit size and to exploit the higher stage work
• Materials are in primis SiC e Si3N4
• The efficiency derating due to low Re are not
  important
• Processing requires precision, simplicity and
  possibility of industrialization

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Before my work
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Before my work
Analysis of Flow and Wing-like Profile
Turbine (in progress)
Compressor
Software FLUENT 6.2
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Before my work
Diffuser
Shaft
Design of compressor from Fluid Analysis
Rotor
Blade
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Before my work
Silicon Carbide (SiC)
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Before my work
Silicon Carbide (SiC)
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Goals of my work in VUT
First Part

1. Preliminary Design
2. Thermal and Structural Analysis
3. Final Design

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My work in VUT
Software Cad Simulation
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Goals of my work in VUT
Second Part

1. Production of model of nanoturbine
2. Mechanical Testing

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My work in VUT
Compressor Analysis
1 step Analysis with traditional methods 2
step Analysis with FEM (Finite Element Method)
Analysis with traditional methods is important to
understand and to evaluate the results of FEM
Analysis
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My work in VUT
Structural Loads

• Centrifugal Force
• Wing Force
• Torque on the shaft

Thermal Loads
- Heat flux by conduction from turbine
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My work in VUT
Structural Loads
Centrifugal Force
Balje
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My work in VUT
Structural Loads
Wing Force
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My work in VUT
Structural Loads
Torque on the shaft
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My work in VUT
Thermal Loads
?T550K (estimated)
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My work in VUT
Structural and Thermal Loads

• Centrifugal Force
• Wing Forces
• Torque on the shaft
• Heat Flux from turbine

Centrifugal Force Heat flux from turbine
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My work in VUT
FEM Analysis
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My work in VUT
Model construction

• Geometry 2D and 3D
• Material characteristics
• Type of analysis
• Quality assessment

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My work in VUT
Model Construction
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My work in VUT
Analysis of results

• Thermal Results
• Structural Results
• Thermo-Structural Results

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My work in VUT
Analysis of results
Displacements
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My work in VUT
Analysis of results
Displacements
Traction Centrifugal Force
Compression Differential Thermal Expansion
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My work in VUT
Thermal result
Temperature Map
assumption 1000K
assumption 300K
assumption 850K
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My work in VUT
Thermal result
Temperature Map
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My work in VUT
Thermal result
Radial Stress
-50 MPa
Sharp corner effect
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My work in VUT
Thermal result
Tangential Stress
110 MPa
-75 MPa
-50 MPa
-220 MPa
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My work in VUT
Thermal result
Axial Stress
-30 MPa
-90 MPa
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My work in VUT
Structural result
Radial Stress
-17 MPa
100 MPa
Sharp corner effect
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My work in VUT
Structural result
Tangential Stress
150 MPa
80 MPa
110 MPa
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My work in VUT
Structural result
Axial Stress
100 MPa
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My work in VUT
Structural and Thermal result
Radial Stress
-50 MPa
75 MPa
Sharp corner effect
200 MPa
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My work in VUT
Structural and Thermal result
Tangential Stress
64?115 MPa
200 MPa
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My work in VUT
Structural and Thermal result
Axial Stress
-50 MPa
90 MPa
-170 MPa
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My work in VUT
Structural and Thermal result
Von Mises Stress (equivalent stress se)
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My work in VUT
Structural and Thermal result
Von Mises Stress
3 MPa
220 MPa
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Conclusions

• The relevant loads are the centrifugal force and
  the differential thermal expansion
• The thermal stress depends on the thickness of
  the compressor disk (thermal gradient)
• In some parts of compressor the intensity of
  stress is high but not fatal
• - The selected material (SiC) is appropriate for
  this technology

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Possible Improvements

• New model with rounded corner to remove the high
  stress (in progress)
• Repeat the analysis with a finer mesh to
  increase resolution
• Join compressor and turbine in the same model to
  evaluate interactions

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Thank you for your attention
Francesco Pace franz.pace_at_tin.it