Numerical investigation of vertical jet flow characteristics for a STOVL aircraft in ground effect

Abstract

This study presents a comprehensive numerical investigation into the jet-induced ground effect aerodynamics of a Short Take-Off and Vertical Landing (STOVL) aircraft. A robust Computational Fluid Dynamics (CFD) framework was first established through a rigorous validation campaign using a full-scale F-35 model. This process identified that a 12-million cell unstructured mesh, combined with the SST k-ω turbulence model, provides the optimal balance between resolving complex impinging jet physics and computational efficiency. Additionally, symmetry analysis confirmed the validity of half-model simulations for longitudinal hover scenarios. Using this framework, the study investigates the sensitivity of the aircraft’s aerodynamic stability and thermal environment to varying engine boundary conditions. A key physical finding is that the ground-induced flow topology is highly coupled with throttle settings: specifically, a reduction in engine power causes the stagnation line of the fountain flow to shift noticeably forward. This migration alters the longitudinal center of pressure, generating a significant nose-down pitching moment that poses challenges for flight control trim strategies. Furthermore, the study quantifies the thermal loads on the fuselage underbelly, demonstrating that reducing jet core temperature mitigates thermal stress. These findings provide critical guidelines for defining STOVL operational margins and thermal protection system design.