GPUs TO MARS Full Scale Simulation of SpaceXs Mars Rocket Engine - - PowerPoint PPT Presentation

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GPUs TO MARS Full Scale Simulation of SpaceXs Mars Rocket Engine - - PowerPoint PPT Presentation

Feb 20, 2024 356 likes •1.24k views

GPUs TO MARS Full Scale Simulation of SpaceXs Mars Rocket Engine Adam Lichtl, Stephen Jones, GTC 2015 Background Independent space launch company Build and operate our own rocket & capsule Operations in CA, TX & FL

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GPUs TO MARS

Full Scale Simulation of SpaceX’s Mars Rocket Engine Adam Lichtl, Stephen Jones, GTC 2015

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Background

  • Independent space launch company
  • Build and operate our own rocket & capsule
  • Operations in CA, TX & FL
  • Founded in 2002, first launch in 2008
  • 18 successful missions to date
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Design

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Build

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Launch

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Mars

Length of day 24 hours, 40 minutes Length of year 687 days Gravity 0.375gs Distance from Sun 1.53 AU Mars Air CO2 (96%), N2 (2%) Earth Air O2 (21%), N2 (78%) Atmosphere 1% density / pressure of Earth Temperature -284 / +86 / -81 F (low / high / avg)

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SLIDE 7

Human Mars Mission Classes

Credit: CollectSpace

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Mass to Mars

Apollo Command & Service Module

  • Mass: 46 tons
  • Terrestrial assembly

NASA Mars Architecture

  • Mass: 300 tons
  • 3x heavy-lift

launches

  • In-orbit assembly

International Space Station

  • Mass: 450 tons
  • 36x Space Shuttle,

5x Proton launches

Image Credit: Mark Benson & Kerbal Space Program Image Credit: NASA Image Credit: NASA

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SLIDE 9

Methane Fuel

O

H H

O O

C

O

H H

O O C

Water from below ground Carbon dioxide from atmosphere Synthesize return-journey fuel on Mars 2H2O + CO2 -> CH4 + 2O2

O O O O

H H

C

H H

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SLIDE 10

Rocket Engine Design

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Why Simulation?

  • 1. Investigate what cannot be measured
  • 2. Reduce need for testing
  • 3. Design optimisation: narrow design space
  • 4. Proactive instead of reactionary design
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SLIDE 12

seconds 10-11 10-9 10-8 10-6 10-10 10-7 10-5 10-3 10-4 Diffusion Reaction Advection Acoustics Chamber Residence

Time scales vary by 8 orders of magnitude

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Total points: (103)6 = 1018 = 1,000,000,000,000,000,000 points @1kB per point -> Yottabytes of data

kmax kmin

log E(k) Injection Cascade Viscous dissipation

Kolmogorov Scale: ~1µm Combustion Chamber: ~1m

Length scales vary by 6 orders of magnitude

Eddy Wavenumber Eddy Energy

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SLIDE 14

Structure in Turbulence

Credit: SpaceWeather

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Simulation Meshing

Structured Grid Adaptive Grid Unstructured Grid

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Fourier Transform: Spectral Compression

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Wavelets: Local Fractal Basis

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Wavelet Compression

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Wavelet Compression

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Wavelet Compression

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Wavelet Compression

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Wavelet Compression

δ

δ > ε (ε is some tolerance) δ < ε

δ

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Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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SLIDE 27

Wavelet Compression

Transform Output

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SLIDE 28

Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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SLIDE 31

Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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SLIDE 33

Wavelet Compression

Transform Output

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SLIDE 34

Wavelet Compression

Transform Output

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Wavelet Compression

Transform Output

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SLIDE 36

Wavelet Compression

Transform Output

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SLIDE 37

Wavelet Compression

Transform Output

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SLIDE 38

Wavelet Compression

Transform Output

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Decompression

Transform Output

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Decompression

Transform Output

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Decompression

Transform Output

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Decompression

+δ

Transform Output

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Decompression

Transform Output

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Decompression

Transform Output

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SLIDE 45

Decompression

Transform Output

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Decompression

Transform Output

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SLIDE 47

Decompression

Transform Output

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SLIDE 54

Regular Grid: Direct Indexing

Index (x, y, z) = p Index (x, y+1, z) = p + Nx

(x, y, z) (x, y+1, z)

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Sparse Grid: Difficult Indexing

Index (x, y, z) = p Index (x, y+1, z) = ???

(x, y, z) (x, y+1, z)

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SLIDE 56

Sparse Grid Point Lookup

Linear search Tree-based search Hybrid tree search + dense indexing

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SLIDE 57

Grid Point Contains Reference to Data

Location (x,y,z) Data Reference (x, y, z)

Grid Point 14

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Grid Point Contains Reference to Data

Location (x,y,z) Data Reference (x, y, z) Grid Index

Grid Point 14

Grid Data 14 15 16 (11,12,5) 8 (11,11,5) 3

(Location) (Reference)

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SLIDE 59

Grid Point Contains Reference to Data

ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 Simulation Data density X-momentum Y-momentum Z-Momentum Energy Location (x,y,z) Data Reference (x, y, z)

Grid Point 14

Grid Data Grid Index 14 15 16 (11,12,5) 8 (11,11,5) 3 … …

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Grid Point Contains Reference to Data

ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 Simulation Data density X-momentum Y-momentum Z-Momentum Energy Location (x,y,z) Data Reference (x, y, z)

Grid Point 14

(11,12,5) 8 (11,11,5) 3 … … Grid Data 14 15 16 Grid Index

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SLIDE 61

P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Grid Adaptation

1 2 3 4 5 6 7 8 x0y0 x1y1 x2y2 x3y3 x4y4 x5y5 x6y6 x7y7 x8y8 x9y9 9 Location Reference Grid Index

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SLIDE 62

P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Grid Adaptation

1 2 3 4 5 6 7 8 x0y0 x1y1 x2y2 x3y3 x4y4 x5y5 x6y6 x7y7 x8y8 x9y9 9 Location Reference Grid Index

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SLIDE 63

P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Grid Adaptation

1 2 3 4 5 6 7 8 x0y0 x1y1 x2y2 x3y3 x4y4 x5y5 x6y6 x7y7 x8y8 x9y9 9 Location Reference Grid Index

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P0 P2 P4 P6 P8

Grid Adaptation

2 4 6 8 x0y0 x2y2 x4y4 x6y6 x8y8 Location Reference Grid Index

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P0 P1 P2 P3 P4

Grid Adaptation

2 4 6 8 x0y0 x2y2 x4y4 x6y6 x8y8 Location Reference Grid Index

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P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Grid Transformations Track Data

1 2 3 4 5 6 7 8 x0y0 x1y1 x2y2 x3y3 x4y4 x5y5 x6y6 x7y7 x8y8 x9y9 9 Location Reference Grid Index

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P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Grid Transformations Track Data

1 2 3 4 5 6 7 8 x0y0 x1y1 x2y2 x3y3 x4y4 x5y5 x6y6 x7y7 x8y8 x9y9 9 Location Reference Delete Add Sort Transpose Grid Index

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SLIDE 68

P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Grid Transformations Track Data

1 2 3 4 5 6 7 8 x0y0 x1y1 x2y2 x3y3 x4y4 x5y5 x6y6 x7y7 x8y8 x9y9 9 Location Reference Grid Index Location Delete Add Sort Transpose Grid Index 4 7 9 5 1 8 3 6 2 Reference x4y4 x7y7 x9y9 x0y0 x5y5 x1y1 x8y8 x3y3 x6y6 x2y2

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P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Losing Coalesced Memory Access

4 7 9 5 1 8 3 6 2 ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 Coalesced Simulation Data Grid Index Reference

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SLIDE 70

P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Losing Coalesced Memory Access

4 7 9 5 1 8 3 6 2 ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 Uncoalesced Simulation Data Grid Index Reference

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P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 4 7 9 5 1 8 3 6 2 x4y4 x7y7 x9y9 x0y0 x5y5 x1y1 x8y8 x3y3 x6y6 x2y2

Restoring Coalesced Memory Access

ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 Uncoalesced Simulation Data Location Reference Grid Index

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SLIDE 72

P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 4 7 9 5 1 8 3 6 2 x4y4 x7y7 x9y9 x0y0 x5y5 x1y1 x8y8 x3y3 x6y6 x2y2 P0 P1 P2 P3 P4 P5 P6 P7 P8 P9

Restoring Coalesced Memory Access

ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 1 2 3 4 5 6 7 8 9

Reorder Simulation Data

Uncoalesced Simulation Data ρu4 ρ4 ρw4 ρv4 E4 ρu7 ρ7 ρw7 ρv7 E7 ρu9 ρ9 ρw9 ρv9 E9 ρu0 ρ0 ρw0 ρv0 E0 ρu5 ρ5 ρw5 ρv5 E5 ρu1 ρ1 ρw1 ρv1 E1 ρu8 ρ8 ρw8 ρv8 E8 ρu3 ρ3 ρw3 ρv3 E3 ρu6 ρ6 ρw6 ρv6 E6 ρu2 ρ2 ρw2 ρv2 E2 Coalesced Simulation Data

Reset Indices

x4y4 x7y7 x9y9 x0y0 x5y5 x1y1 x8y8 x3y3 x6y6 x2y2 Location Reference Grid Index

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Coupled Multi-Physics

Chemistry Diffusion Advection Thermodynamics

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Real Gas Properties

Extreme pressure requires real-gas properties, evaluated at each grid node

  • Viscosity
  • Conductivity
  • Diffusion constants
  • Per-species diffusion rates

Independent Calculations Massively Parallelizable

O2 phase diagram, Z-axis is density

(colour: liquid is blue, gas is white) Pressure Temperature

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Strong Temperature Dependence

Arrhenius equation includes temperature in exponent

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Chemical Kinetic Model

H H

O

H H

O O O

H H H H +

H2 O2 H2O

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SLIDE 79

Chemical Kinetic Model

O

H

OH

O

O

O

H

O

HO2

H

O

H

O

H2O2

H

H

H H

O

H H

O O O

H H H H +

H2 O2 H2O

X

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SLIDE 80

Chemical Kinetic Model

O

H

OH

O

O

O

H

O

HO2

H

O

H

O

H2O2

H

H

H H

O

H H

O O O

H H H H +

H2 O2 H2O

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SLIDE 81

Methane Chemistry

O O O O

H

C

H H H +

O2 CH4

H H

O

H H

O

C

O O

+

H2O CO2

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SLIDE 82

Methane Chemistry

O O O O

H

C

H H H +

O2 CH4

H H

O

H H

O

C

O O

+

H2O CO2 53 Species, 325 Reactions

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SLIDE 83
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SLIDE 84

(Actual simulation data, rendered with a ray tracer)

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Acknowledgements

Oleg Vasilyev, University of Colorado Boulder Department of Mechanical Engineering Jonathan Regele, Iowa State University Department of Aerospace Engineering Don Lamb The Flash Center for Computational Science Joseph Oefelein, Sandia National Laboratories Combustion Research Facility Praveen Ramaprabhu University of North Carolina at Charlotte Marc Massot Ecole Centrale, Paris

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SLIDE 86

Want To Help?

If you have a software or physics background and you’re interested in working with us, please contact research@spacex.com