Abstract:

As a critical component of aircraft energy systems, the precision of fuel quantity measurement within aircraft fuel tanks is paramount, directly influencing flight safety, operational stability, and mission range planning. However, to optimize the aerodynamic layout and maximize space utilization within the fuselage, modern aircraft fuel tanks are frequently designed with highly irregular geometries. These containers often incorporate complex internal structures, including stiffeners, baffles, and surge boxes, which significantly complicate the relationship between liquid level height and actual fuel volume. Consequently, during dynamic flight maneuvers such as climbing, diving, or rolling, traditional measurement techniques relying solely on single-point liquid-level sensors fail to accurately reflect the true fuel quantity, leading to potential safety hazards and inefficient fuel management. To address the challenging fuel-volume calculation within tanks possessing such complex internal architectures, this research introduced an innovative volume calculation algorithm based on a mesh folding technique. This approach bypassed the need for simplified geometric assumptions, instead leveraging high-fidelity three-dimensional data. The computational procedure was systematic and robust: initially, comprehensive mesh topology information was extracted directly from the fuel tank’s STL (STereoLithography) format file. Subsequently, by integrating real-time aircraft attitude data, specifically pitch and roll angles, with sensor-derived liquid level, the exact spatial position and orientation of the fuel liquid plane were determined. Once the liquid plane was established, the algorithm identified all mesh elements that intersected with this plane. These specific elements underwent a precise division and reconstruction process to align perfectly with the fluid boundary. Following this reconstruction, a unique “folding” operation was executed: all mesh components located above the liquid plane were virtually folded and projected down onto the liquid plane surface. This transformation effectively converted the complex problem of calculating a partial volume within an irregular, tilted container into a straightforward summation of closed mesh volumes. Finally, the volumes of all processed mesh elements below the projected plane were aggregated to yield the precise total fuel volume. When evaluated against conventional volume-calculation strategies, such as the slicing, convex-hull, and voxel methods, the proposed mesh-folding technique demonstrated distinct and significant advantages. The traditional slicing method, although intuitive, was prone to substantial errors during cross-sectional reconstruction when dealing with intricate internal baffles and often requried excessive computational time when high precision was required. The convex hull method was fundamentally limited by its inability to accurately model the non-convex geometric features inherent in most fuel tanks. Similarly, the voxel method faced a persistent dilemma: achieving high resolution requires prohibitive computational resources, whereas lowering resolution compromised accuracy. In contrast, the mesh folding method exhibited exceptional universal applicability. It was not limited by the complexity of internal tank structures and completely eliminated the tedious and time-consuming steps associated with complex cross-sectional mesh reconstruction. As a result, this approach achieved a superior balance, delivering high-precision calculations at speeds suitable for real-time onboard applications. To rigorously validate the performance of this algorithm, extensive comparative simulations were conducted. The proposed method was benchmarked against the slicing, voxel, and Monte Carlo methods across a diverse set of model characteristics, varying both the number of mesh faces and the degree of geometric concavity. These tests confirmed the algorithm’s robustness, demonstrating its consistent accuracy and superior computational efficiency regardless of model complexity. Furthermore, the practical viability of the method was verified through physical experiments on an actual aircraft fuel tank. By simulating various flight attitudes and comparing the algorithm’s output with empirical measurements obtained from controlled filling and weighing tests, the results showed strong consistency between simulation and experiment. This close alignment not only validated the theoretical framework but also demonstrated the method’s readiness for engineering application, offering a reliable technical pathway for the development of next-generation high-precision fuel measurement systems.

Key words: volume calculation, triangular mesh, fuel tank, STereoLithography model, mesh folding