UNIVERSITY OF ROME LA SAPIENZA Department of Mechanics and Aeronautics DESIGN OF A NANO-GAS TURBINE Thermal and Structural Analysis Pace Francesco
Why nanoturbine? Displacement of human activities Increased use of mobile and stand alone devices Applications: Need to provide energy in discontinuos, efficient and serviceable way military use (powering of equipment, aeronautic propulsion, etc.) electro-medical equipment telecommunication
Nanoturbine
Hypothesis and Experience Definition of Performance DESIGN Tecnological know-how Flow,Thermal and Structural Equations Numerical Simulation and Test
Before my work Explanation of Mechanical, Thermal and Kinematic Characteristics Preliminary Design of Impeller and Stator of Compressor
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 Si 3 N 4 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 Compressor Turbine (in progress) Software: FLUENT 6.2
Before my work Shaft Diffuser Rotor Design of compressor from Fluid Analysis Blade
Before my work Silicon Carbide (SiC)
Before my work Silicon Carbide (SiC)
Goals of my work in VUT First Part 1) Preliminary Design 2) Thermal and Structural Analysis 3) Final Design
Software Cad: Simulation:
Goals of my work in VUT Second Part 1) Production of model of nanoturbine 2) Mechanical Testing
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
- Centrifugal Force - Wing Force - Torque on the shaft Structural Loads Thermal Loads - Heat flux by conduction from turbine
Centrifugal Force Structural Loads Balje
Structural Loads Wing Force
Structural Loads Torque on the shaft
Thermal Loads ΔT=550K (estimated)
- Centrifugal Force -Wing Forces - Torque on the shaft - Heat Flux from turbine Structural and Thermal Loads Centrifugal Force + Heat flux from turbine
FEM Analysis 1. Model construction 2. Analysis of results 3. Optimization
Model construction - Geometry 2D and 3D - Material characteristics - Type of analysis - Quality assessment
Model Construction
Analysis of results - Thermal Results - Structural Results - Thermo-Structural Results
Analysis of results Displacements
Traction: Centrifugal Force Analysis of results Displacements Compression: Differential Thermal Expansion
assumption: 300K My work in VUT Thermal result Temperature Map assumption: 1000K assumption : 850K
Thermal result Temperature Map
Thermal result Radial Stress Sharp corner effect -50 MPa
Thermal result Tangential Stress 110 MPa -50 MPa -75 MPa -220 MPa
Thermal result Axial Stress -30 MPa -90 MPa
Structural result Radial Stress -17 MPa 100 MPa Sharp corner effect
Structural result Tangential Stress 150 MPa 80 MPa 110 MPa
Structural result Axial Stress 100 MPa
Structural and Thermal result Radial Stress -50 MPa Sharp corner effect 75 MPa 200 MPa
Structural and Thermal result Tangential Stress 64 115 MPa 200 MPa
Structural and Thermal result Axial Stress -50 MPa -170 MPa 90 MPa
Structural and Thermal result Von Mises Stress (equivalent stress σ e )
Structural and Thermal result Von 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
Thank you for your attention Francesco Pace franz.pace@tin.it