Fuel Consumer Model

Description

The Fuel Consumer Model enables fuel consumption for spacecraft components such as thrusters. It connects to the fuel network via the Fuel Bus and requests a desired mass flow rate from upstream sources. The Fuel System solves the network to determine the actual flow delivered based on source availability, valve states, and pump capacity.

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Example Use Cases

• Thruster Fuel Feed: Model propellant consumption for chemical or electric thrusters.
• Flow-Limited Operation: Simulate thruster performance degradation when fuel supply cannot meet demand.
• Multi-Source Configurations: Connect a consumer to multiple fuel sources through valves or pumps for redundancy.

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Module Implementation

Flow Request

The consumer declares a desired ingoing flow rate representing the mass flow required for nominal operation:

$${\dot{m}}_{\text{desired}}\ge 0$$

The Fuel System evaluates the network and computes the provided flow rate based on what upstream sources can deliver:

$${\dot{m}}_{\text{provided}}\le {\dot{m}}_{\text{desired}}$$

When the network can fully satisfy the demand, the provided rate equals the desired rate. When sources are depleted or flow is restricted, the provided rate is reduced accordingly.

Network Connections

The consumer exposes an Intake port for connecting to upstream fuel components. Valid connections include:

Upstream Component	Connection
Fuel Source	Tank → Intake
Fuel Valve	Outlet → Intake
Fuel Pump	Downstream → Intake

Connections are managed through the spacecraft’s Fuel Bus. The consumer can connect to multiple upstream components, and the Fuel System will aggregate available flow from all connected paths.

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Assumptions/Limitations

• The consumer model does not perform flow solving; it only declares demand and receives the solved result from the Fuel System.
• Flow rates are always non-negative; the consumer cannot push fuel back into the network.
• The model does not distinguish between fuel types; fuel compatibility is assumed when connected.
• Performance effects from insufficient fuel supply must be implemented by the parent component (e.g., thruster thrust reduction).