Thermo-mechanical Coupling Model

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

Definition

The thermo-mechanical coupling model describes how thermal state (temperature, pressure, density) and flight state (position, velocity, attitude) of a stratospheric airship mutually influence and constrain each other. Unlike conventional aircraft, a stratospheric airship's thermal state directly determines buoyancy changes, affecting flight performance.

Coupling Mechanisms

Thermal to Mechanical

Thermal Variable	Mechanical Effect	Physical Mechanism
Helium temperature $T_{He}$	Buoyancy change	$\rho_{He} = p/(RT_{He})$
Skin temperature $T_{skin}$	Aerodynamic heating	Boundary layer effects
Pressure $p_{He}$	Envelope expansion	$V = nRT/p$

Mechanical to Thermal

Mechanical Variable	Thermal Effect	Physical Mechanism
Altitude $h$	Atmospheric density	$\rho_{air}(h)$ affects convection
Velocity $v$	Aerodynamic heating	$Q_{dyn} = \frac{1}{2}\rho v^3$
Attitude $\theta$	Solar incidence angle	Affects direct solar input

Core Coupling Variables

1. Helium Density

\rho_{He} = \frac{p_{He} M_{He}}{RT_{He}}

2. Buoyancy

B = (\rho_{air} - \rho_{He}) V_{He} g

Diurnal Cycle Effects

Time	$T_{He}$	$B$	Flight State
Noon	High	Low	Net ascent tendency
Midnight	Low	High	Net descent tendency

References

Wang H, et al. Thermo-mechanical Coupling Analysis for Stratospheric Airship[J]. AIAA Journal, 2025.
Li J, Chen W. Coupled Thermal-Flight Dynamics of High Altitude Airships[J]. IEEE Transactions on Aerospace Systems, 2024.