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 Need to provide energy in discontinuos, efficient and serviceable way Applications:  military use (powering of equipment, aeronautic propulsion, etc.)  electro-medical equipment  telecommunication

Nanoturbine

DESIGN Flow,Thermal and Structural Equations Definition of Performance Tecnological know-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 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

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 VUT Analysis of results Displacements

My work in VUT Analysis of results Displacements Compression: Differential Thermal Expansion Traction: Centrifugal Force

My work in VUT Thermal result Temperature Map assumption: 300K assumption : 850K assumption: 1000K

My work in VUT Thermal result Temperature Map

My work in VUT Thermal result Radial Stress -50 MPa Sharp corner effect

My work in VUT Thermal result Tangential Stress 110 MPa -75 MPa -220 MPa -50 MPa

My work in VUT Thermal result Axial Stress -30 MPa -90 MPa

My work in VUT Structural result Radial Stress -17 MPa 100 MPa Sharp corner effect

My work in VUT Structural result Tangential Stress 150 MPa 110 MPa 80 MPa

My work in VUT Structural result Axial Stress 100 MPa

My work in VUT Structural and Thermal result Radial Stress -50 MPa 75 MPa 200 MPa Sharp corner effect

My work in VUT Structural and Thermal result Tangential Stress 64  115 MPa 200 MPa

My work in VUT Structural and Thermal result Axial Stress 90 MPa -50 MPa -170 MPa

My work in VUT Structural and Thermal result Von Mises Stress (equivalent stress σ e )

My work in VUT 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