Nodes: rocket engine junctions and boundary conditions

Nodes represent junction points in the fluid system where multiple branches can connect. They serve as boundary conditions or internal connection points for the rocket engine simulation.

Overview

The Meco Rocket Simulator supports 6 different node types, organized into liquid and gas system categories:

Liquid System Nodes

NodeInlet

• Type: NodeInlet
• Purpose: Inlet boundary condition for liquid systems (tanks, external sources)
• Parameters:
  • name - Component name (string)
  • fluid - Fluid type (string, e.g., "H2", "O2", "RP1")

Example JSON:

{
  "name": "LH Tank Inlet",
  "category": 1,
  "type": "NodeInlet",
  "fluid": "H2"
}

NodeOutlet

• Type: NodeOutlet
• Purpose: Outlet boundary condition (fixed to Helium - typically atmosphere)
• Parameters:
  • name - Component name (string)

Notes: Fluid type is automatically set to Helium ("He")

Example JSON:

{
  "name": "Ambient Outlet",
  "category": 1,
  "type": "NodeOutlet"
}

NodeInternal

• Type: NodeInternal
• Purpose: Internal junction for liquid systems (manifolds, junctions)
• Parameters:
  • name - Component name (string)
  • volume - Node volume in m³ (double)

Example JSON:

{
  "name": "LH HP Junction",
  "category": 1,
  "type": "NodeInternal",
  "volume": 9.503317777109124e-9
}

Gas System Nodes

NodeGasInlet

• Type: NodeGasInlet
• Purpose: Inlet boundary condition for gas systems
• Parameters:
  • name - Component name (string)
  • fluidGas - Gas fluid type (string, e.g., "O2_H2", "Air")

Example JSON:

{
  "name": "Gas Generator Inlet",
  "category": 1,
  "type": "NodeGasInlet",
  "fluidGas": "O2_H2"
}

NodeGasInternal

• Type: NodeGasInternal
• Purpose: Internal junction for gas systems
• Parameters:
  • name - Component name (string)
  • volume - Node volume in m³ (double)

Example JSON:

{
  "name": "TC Nozzle Joint",
  "category": 1,
  "type": "NodeGasInternal",
  "volume": 2.733971006786517e-7
}

NodeGasGenerator

• Type: NodeGasGenerator
• Purpose: Gas generator combustion chamber with oxidizer-fuel equilibration
• Parameters:
  • name - Component name (string)
  • fluidGas - Gas mixture type (string, e.g., "O2_H2")
  • volume - Chamber volume in m³ (double)

Example JSON:

{
  "name": "GG Head",
  "category": 1,
  "type": "NodeGasGenerator",
  "fluidGas": "O2_H2",
  "volume": 3.141592653589793e-8
}

Supported Fluids

Liquid Fluids

• H2 - Hydrogen
• O2 - Oxygen
• RP1 - Rocket Propellant 1 (kerosene)
• He - Helium (outlets)

Gas Mixtures

• O2_H2 - Oxygen-Hydrogen combustion products
• Air - Standard atmospheric air
• Custom mixtures as defined in the fluid property database

Usage Guidelines

1. Naming Convention: Use descriptive names that indicate the node's location and purpose
2. Volume Sizing: Internal node volumes should represent physical junction volumes
3. Boundary Conditions: Inlets represent fixed fluid sources, outlets represent fixed pressure sinks
4. Gas Generators: Use for combustion modeling with automatic oxidizer-fuel equilibration
5. Connection Order: Nodes must be defined before branches that reference them

Common Applications

• Tank Connections: Use NodeInlet for propellant tank outlets
• Atmospheric Exhaust: Use NodeOutlet for nozzle exits to atmosphere
• Manifolds: Use NodeInternal for complex piping junction points
• Combustion Chambers: Use NodeGasGenerator for gas generator and main chamber modeling
• Gas Lines: Use NodeGasInternal for gas system junctions and plenums

See Also

• Main Components Overview
• Branch Components
• Control Parameters
• Fluid Property Database Reference

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