university of rome “la sapienza” department of mechanics and aeronautics design of a nano-gas...
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UNIVERSITY OF ROME “LA SAPIENZA”UNIVERSITY OF ROME “LA SAPIENZA”
Department of Mechanics and Aeronautics
DESIGN OF A NANO-GAS TURBINE
Thermal and Structural Analysis
Pace Francesco
WhyWhy nanoturbinenanoturbine??
Displacement of human activitiesDisplacement of human activities Increased use of mobile and stand alone devicesIncreased use of mobile and stand alone devices
Need to provide energy in discontinuos, efficient and
serviceable wayApplications:
military use (powering of equipment, aeronautic propulsion, etc.)
electro-medical equipment
telecommunication
NanoturbineNanoturbine
DESIGN
Flow,Thermal and Structural Equations
Definition ofPerformance
Tecnologicalknow-how
Hypothesis and Experience
Numerical Simulation and Test
Before my work
Preliminary Design of Impeller and Stator of
Compressor
Explanation of Mechanical, Thermal and Kinematic Characteristics
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
Before my work
Before my work
Analysis of Flow and
Wing-like Profile
Turbine
(in progress)
Compressor
Software: FLUENT 6.2
Diffuser
Rotor
Shaft
Blade
Design of compressor from Fluid Analysis
Before my work
Silicon Carbide (SiC)
Before my work
Silicon Carbide (SiC)
Before my work
Goals of my work in VUT
1) Preliminary Design
2) Thermal and Structural Analysis
3) Final Design
First Part
My work in VUT
Software
Cad:
Simulation:
Goals of my work in VUT
Second Part
1) Production of model of nanoturbine
2) Mechanical Testing
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
My work in VUT
Structural Loads
- Centrifugal Force
- Wing Force
- Torque on the shaft
Thermal Loads
- Heat flux by conduction from turbine
My work in VUT
Structural Loads
Centrifugal Force
Balje
My work in VUT
Wing Force
Structural Loads
My work in VUT
Torque on the shaft
Structural Loads
My work in VUT
Thermal Loads
T=550K (estimated)
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
My work in VUT
FEM Analysis
2. Analysis of results
3. Optimization
1. Model construction
My work in VUT
Model construction
- Geometry 2D and 3D
- Material characteristics
- Type of analysis
- Quality assessment
My work in VUT
Model Construction
My work in VUT
Analysis of results
- Thermal Results
- Structural Results
- Thermo-Structural Results
My work in VUTAnalysis of results
Displacements
My work in VUTAnalysis of results
Displacements
Compression:
Differential Thermal Expansion
Traction: Centrifugal
Force
My work in VUTThermal result
Temperature Mapassumption:
300K
assumption :
850K
assumption:
1000K
My work in VUTThermal result
Temperature Map
My work in VUTThermal result
Radial Stress
-50 MPaSharp corner effect
My work in VUT
Thermal result
Tangential Stress
110 MPa
-75 MPa
-220 MPa
-50 MPa
My work in VUTThermal result
Axial Stress
-30 MPa
-90 MPa
My work in VUTStructural result
Radial Stress
-17 MPa
100 MPa
Sharp corner effect
My work in VUTStructural resultTangential Stress
150 MPa
110 MPa
80 MPa
My work in VUTStructural result
Axial Stress
100 MPa
My work in VUTStructural and Thermal
resultRadial Stress
-50 MPa
75 MPa
200 MPa
Sharp corner effect
My work in VUTStructural and Thermal
resultTangential Stress
64115 MPa
200 MPa
My work in VUTStructural and Thermal
resultAxial Stress
90 MPa
-50 MPa
-170 MPa
My work in VUTStructural and Thermal
result
Von Mises Stress (equivalent stress σe)
My work in VUTStructural and Thermal
resultVon Mises Stress
3 MPa
220 MPa
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
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
