Thermodynamic Model

Author: CislunarSpace
Site: https://cislunarspace.cn

Definition

The thermodynamic model describes how helium temperature and thermodynamic state inside a stratospheric airship envelope vary with external environment (solar radiation, earth albedo, IR radiation, convection) and internal state (helium inflation/deflation, payload heat).

Energy Balance Equation

Overall Form

Q_{net} = Q_{solar} + Q_{albedo} + Q_{IR,earth} - Q_{IR,sky} - Q_{conv} - Q_{cond}

Two-node vs Seven-node Models

Model	Description	Application
Two-node	Skin + Helium nodes	Preliminary analysis, fast estimation
Seven-node	Distributed nodes by location	Detailed design, transient analysis

Thermo-mechanical Coupling

Coupling Variables

Variable	Thermal→Dynamic	Dynamic→Thermal
Helium density $\rho_{He}$	Affects buoyancy	Varies with altitude
Volume $V_{He}$	Thermal expansion	Deformation
Temperature $T_{He}$	Solar heating	Compression work

References

da Silva M G, et al. Thermal Modeling of High Altitude Airships[J]. Journal of Aircraft, 2024.
Wang H, Chen W. Thermodynamic Modeling and Simulation for Stratospheric Airship[J]. Acta Aeronautica, 2025.