Optimization of Heat Dissipation Structure for Fiber-Optic Gyroscope Inertial Navigation System Based on Fluid-Thermal Coupling Analysis

This study proposed a heat dissipation optimization method for fiber optic gyroscopes (FOGs) based on Multiphysics coupling simulation, achieving heat dissipation structure optimization and thermal-fluid coupling analysis through the construction of a three-dimensional multi-spherical-shell thermodynamic model for FOGs. A Multiphysics coupling numerical model incorporating the Navier-Stokes equations, energy conservation equation, and unsteady heat transfer equation was established to analyze the interaction mechanism between fan air flux and shield shell aperture parameters under forced convection heat dissipation conditions. Numerical simulations showed that expanding the aperture size from the reference value to the optimized threshold produces a significant temperature reduction effect of 4.15%, and the average system operating temperature decreases by 7.13% when combined with dynamic air volume heat dissipation. A NSGA-II multi-objective optimization framework built in MATLAB successfully obtained a Pareto front solution set, with relative errors in heat transfer power and temperature field controlled within 5.37% under steady-state conditions—outperforming traditional empirical design methods. Experimental verification demonstrated that the optimized heat dissipation structure maintains a stable temperature in the range of 25.0–28.56°C during transient analysis, and the average relative error between simulated and measured temperature data for each channel during the transient process is less than 2.91%. This research revealed the coupling law between multi-scale heat conduction and fluid dynamics in FOGs, providing a new theoretical framework for thermal design in inertial navigation systems. The proposed optimization method has been adopted in the engineering application of a high-precision FOG model.