Liquid Propellant Sloshing: A study about the use of Open Source CFD Software. T. Rebelo, M. Hahn, F. Cirillo

Transcription

1 Liquid Propellant Sloshing: A study about the use of Open Source CFD Software T. Rebelo, M. Hahn, F. Cirillo 5 th of March, 2015

2 Acknowledgements Ph.D. Jennifer Kingston Ph.D. Johnny Ejemalm Ph.D. Peter Råback 2

3 Outline 1. Introduction 2. Sloshing: A brief Introduction 3. Requirements 4. CFD Software Selection & Setup 5. Test Case 1: Rectangular Tank 6. Test Case 2: Cylindrical Tank 7. Test Case 3: Cylindrical Tank w/ Hemispherical Domes 8. Conclusions 3

4 1. Introduction Problem Liquid Propellant Sloshing Dynamics of the Spacecraft How? Moving Fuel Forces Torques Solid body AOCS Pointing Performance Unstable Attitude and Orbit Control 4

5 1. Introduction Aim CFD Code Propellant Sloshing Airbus Defence & Space Analysis Simulation Environment (Pre- and Post- Processing) 5

6 2. Sloshing: A Brief Introduction Sloshing Any motion of a free liquid surface caused by any disturbance to a rigid container partially filled with liquid. Lateral Sloshing Defined as the formation of a standing wave on the surface of a liquid when a tank partially filled is laterally excited. The simplest way of liquid sloshing inside containers. 6

7 3. Requirements Functional Requirements 1. Perform lateral sloshing analysis; 2. Model real physical problems; 3. Support arbitrary tank geometries; 4. Consider viscosity effects; System Requirements 1. Open source software; 2. Based on FEM or FVM; 3. Interface with MATLAB ; 4. Usable in any OS. 5. Accurate for small Re - laminar regime; 6. Accurate for high-g conditions; 7. Results validated for the defined test cases. 7

8 4. CFD Software Selection & Setup Available Codes CFD Solver Open source software 40 Codes FEniCS Project OpenFOAM SU2 Fluidity Code_Saturne Final Selection Elmer FEM based Solves N-S using an ALE approach (two-phase flow) Integrated Simulation Environment Pre- and Post- Processing tools 8

9 5. Rectangular Tank Test A Evaluate the first antisymmetric sloshing frequency Vertical acceleration: g = - 1 m/s 2 Fluid 1: µ = 1.0 Pa.s ; ρ = 1000 kg/m 3 Fluid 2: µ = 0.01 Pa.s ; ρ = 1 kg/m 3 9

10 5. Rectangular Tank Test B Obtain the first antisymmetric sloshing frequencies along the long and shorter directions of a tank Vertical acceleration: g = m/s 2 h = m Liquid water Air 10

11 5. Rectangular Tank Test B Excitation along the Tank s Longer Direction 11

12 5. Rectangular Tank Test B Excitation along the Tank s Shorter Direction 12

13 6. Cylindrical Tank Test Obtain the first antisymmetric sloshing frequency Vertical acceleration: g = m/s 2 Liquid water Air 13

14 7. Cylindrical tank with hemispherical domes Test A Recognize the natural sloshing frequencies (2 liquid propellants) Vertical acceleration: g = m/s 2 Different liquid propellants: MON-3 MMH Pressurized Helium 14

15 7. Cylindrical tank with hemispherical domes Test A MON-3 & MMH (25%, 50% & 75% fill ratio) f = 0.90 Hz 1 st antisymmetric sloshing frequency f = 1.40 Hz 1 st symmetric sloshing frequency f = 1.60 Hz 2 nd antisymmetric sloshing frequency f = 1.95 Hz 2 nd symmetric sloshing frequency PSD frequency resolution: 0.05 Hz 15

16 7. Cylindrical tank with hemispherical domes Test B Accurately determine the 1 st antisymmetric natural sloshing frequency (2 liquid propellants 50% fill ratio) Accuracy: ± 0.01 Hz 16

17 7. Cylindrical tank with hemispherical domes Test C Obtain the liquid propellant s damping ratio after removal of a 0.1-g lateral acceleration (2 liquid propellants 50% fill ratio) Estimate the mass participating in the sloshing movement after the abrupt removal of the lateral acceleration MON-3 = 2,3 % MMH = 2,5%? Mass participating in the sloshing movement 30 % 17

18 8. Conclusions An open source CFD software was chosen based on specific requirements A fully functional sloshing simulation environment was developed The results obtained in the simple rectangular and cylindrical tank test cases validated the software for simple lateral sloshing problems The results obtained for test case 3 are in-line with those expected, except for: Damping Ratio Mass of liquid participating in the sloshing movement Reason? - Mass loss phenomenon? Numerical damping? Open source CFD software seem to be a good alternative to commercial solutions 18

19 Thank You! Rua Eng.Frederico Ulrich 2650 (TECMAIA) Maia, Portugal Tel.: Fax: Tiago Rebelo 19