DESIGN OF A NANO-GAS TURBINE

Transcription

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

2 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

3 Nanoturbine

4 Hypothesis and Experience Definition of Performance DESIGN Tecnological know-how Flow,Thermal and Structural Equations Numerical Simulation and Test

5 Before my work Explanation of Mechanical, Thermal and Kinematic Characteristics Preliminary Design of Impeller and Stator of Compressor

6 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

7 Before my work

8 Before my work Analysis of Flow and Wing-like Profile Compressor Turbine (in progress) Software: FLUENT 6.2

9 Before my work Shaft Diffuser Rotor Design of compressor from Fluid Analysis Blade

10 Before my work Silicon Carbide (SiC)

11 Before my work Silicon Carbide (SiC)

12 Goals of my work in VUT First Part 1) Preliminary Design 2) Thermal and Structural Analysis 3) Final Design

13 Software Cad: Simulation:

14 Goals of my work in VUT Second Part 1) Production of model of nanoturbine 2) Mechanical Testing

15 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

16 - Centrifugal Force - Wing Force - Torque on the shaft Structural Loads Thermal Loads - Heat flux by conduction from turbine

17 Centrifugal Force Structural Loads Balje

18 Structural Loads Wing Force

19 Structural Loads Torque on the shaft

20 Thermal Loads ΔT=550K (estimated)

21 - Centrifugal Force -Wing Forces - Torque on the shaft - Heat Flux from turbine Structural and Thermal Loads Centrifugal Force + Heat flux from turbine

22 FEM Analysis 1. Model construction 2. Analysis of results 3. Optimization

23 Model construction - Geometry 2D and 3D - Material characteristics - Type of analysis - Quality assessment

24 Model Construction

25 Analysis of results - Thermal Results - Structural Results - Thermo-Structural Results

26 Analysis of results Displacements

27 Traction: Centrifugal Force Analysis of results Displacements Compression: Differential Thermal Expansion

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

29 Thermal result Temperature Map

30 Thermal result Radial Stress Sharp corner effect -50 MPa

31 Thermal result Tangential Stress 110 MPa -50 MPa -75 MPa -220 MPa

32 Thermal result Axial Stress -30 MPa -90 MPa

33 Structural result Radial Stress -17 MPa 100 MPa Sharp corner effect

34 Structural result Tangential Stress 150 MPa 80 MPa 110 MPa

35 Structural result Axial Stress 100 MPa

36 Structural and Thermal result Radial Stress -50 MPa Sharp corner effect 75 MPa 200 MPa

37 Structural and Thermal result Tangential Stress MPa 200 MPa

38 Structural and Thermal result Axial Stress -50 MPa -170 MPa 90 MPa

39 Structural and Thermal result Von Mises Stress (equivalent stress σ e )

40 Structural and Thermal result Von Mises Stress 3 MPa 220 MPa

41 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

42 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

43 Thank you for your attention Francesco Pace