Aviation, Rocket and Technology . Vestnik MGTU

Modelling of CubeSat satellite motion with inflatable braking device. Part 1. Determination of aerodynamic characteristics and trajectory parameters

Tue, 28 Jul 2026 00:00:00 +0400

The article is devoted to the analysis of loading of the inflatable spherical shell of the braking device of a CubeSat 1U microsatellite during its descent from a 500 km high operational orbit. An iterative approach combining the interrelated processes of numerical modelling of the flow and determination of the descent trajectory parameters of the inflatable braking device was developed. Using the approach, the state of the shell under free-molecular gas flow was investigated, the pressure fields and heat flux density on the shell surface were determined using OpenFoam, and the dependences of aerodynamic coefficients on altitude and flight speed were determined. To verify the validity of the results obtained by modelling in OpenFoam, an additional study in Ansys Fluent was performed. The comparative analysis demonstrated good convergence of the results of two independent computational methods, which confirms the correctness of the calculations. The obtained data were used in the construction of a mathematical model of motion of the ‘microsatellite-NTU’ bundle in Comsol MultiPhysics. As a result, the trajectory profile was obtained at the section of the bundle descent from the working altitude of 500 km to the upper boundary of the Earth’s atmosphere of 100 km. The results obtained can be used for further analyses of the stress-strain and temperature state of the bundle.
EDN: UHUJOL, https://elibrary/uhujol

Theoretical and experimental study of thermal conductivity and operational limits of a sodium axial heat pipe relative to the gravity vector orientation

Fri, 31 Jul 2026 00:00:00 +0400

This paper presents an assessment of the influence of gravitational force vector orientation on the performance of a sodium axial heat pipe. The effect of axial heat pipe orientation on its limiting operational factors, such as the sonic limit, viscous limit, boiling limit, and capillary limit, is demonstrated. Comprehensive numerical simulation was carried out based on a detailed two-dimensional thermal-hydraulic model, which takes into account the spatial distribution of parameters along the pipe length, such as temperature, pressure, and velocity fields. This approach also enables the determination of the distribution of the maximum allowable heat input to the evaporator zone of the axial heat pipe. It was established that the limiting factor is the sonic limit, which amounts to 450 W for an axial heat pipe with a length of 350 mm, wick thickness of 0.5 mm, vapor channel diameter of 7 mm, and casing diameter of 10 mm. Investigation of the dependence on the inclination angle showed a moderate increase in thermal resistance and a decrease in the average temperature within the axial heat pipe circuit. Thus, this work has localized a "weak link" in the design—the vapor channel, whose performance is constrained by the sonic limit. The obtained results determine the feasibility of optimizing the geometry of the vapor path to increase the overall power of the axial heat pipe.
EDN: DRHATK, https://elibrary/drhatk